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Field Study of the Rotary Desiccant System Using the Cromer Cycle


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FIELD STUDY OF THE ROTARY DESICCANT SYSTEM USING THE CROMER CYCLE By BRONISLAVA VELTCHEVA A THESIS PRESENTED TO THE GRADUATE SCHOOL OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF SCIENCE UNIVERSITY OF FLORIDA 2003

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ACKNOWLEDGMENTS First of all I would like to express my deep appreciation to Dr. Yogi Goswami, my advisor and committee chairman, for his guidance, tremendous support and understanding over the last 2 years. I wish to thank my other committee members, Dr. S. A. Sherif and Dr. D. W Hahn, for their expert advice and guidance. Special thanks go to Dr. H. A. (Skip) Ingley for his constructive recommendations and helpful suggestions during my research. I would like also to thank Dr. Charlie Cromer for the discussions on his technology. Sincere thanks go to Mr. Charles Garretson for his patience and valuable support in constructing the experimental setup. Very sincere thanks go to my husband, Ivan, without whose motivation, belief in my abilities and abundant love and support this degree would never have been possible. Last, but not least, I wish to express my deep gratitude to my great cousin Ani and her husband Nathan for their measureless support and constant positivism. They made this experience more enjoyable and rewarding. ii

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TABLE OF CONTENTS page ACKNOWLEDGMENTS..................................................................................................ii LIST OF TABLES...............................................................................................................v LIST OF FIGURES...........................................................................................................vi LIST OF ABBREVIATIONS..........................................................................................viii ABSTRACT.........................................................................................................................x CHAPTER 1 INTRODUCTION.......................................................................................................1 1.1 Why Air Conditioning..........................................................................................2 1.2 Desiccant Cooling Concept..................................................................................3 2 CROMER CYCLE......................................................................................................5 2.1 Parameters That Impact Cromer Cycle Performance..........................................8 2.2 Literature Review..............................................................................................11 2.3 Objectives of the Present Study.........................................................................12 3 EXPERIMENTAL SETUP.......................................................................................14 3.1 Experimental Facility........................................................................................14 3.2 Measuring Instrumentation................................................................................15 3.2 Desiccant Wheel................................................................................................18 3.3 Condensate Measuring Equipment....................................................................24 3.4 Data Acquisition System...................................................................................24 4 PROTOCOL AND EXPERIMENTAL RESULTS..................................................27 4.1 Protocol.............................................................................................................27 4.2 Experimental Results.........................................................................................29 4.3 Discussion.........................................................................................................49 5 CONCLUSIONS.......................................................................................................60 iii

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APPENDIX A DATA SETS.............................................................................................................62 B UNCERTAINTY ANALYSIS..................................................................................67 C FORTRAN 77 PROGRAM......................................................................................73 D LATENT COOLING TRENDLINES.......................................................................77 LIST OF REFERENCES...................................................................................................81 BIOGRAPHICAL SKETCH.............................................................................................83 iv

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LIST OF TABLES Table page 1-1 Use of air-conditioning equipment in the USA households ......................................2 2-1 Performance comparison of a standard air handler to the same equipped with the Cromer cycle equipment........................................................................12 4-1 Ambient conditions and run times for the data pairs from the baseline set and Cromer set No.1.............................................................................................33 4-2 Ambient conditions and run times for the data pairs from the baseline set and Cromer set No.2.............................................................................................42 4-3 Ambient conditions and run times for the data pairs from the baseline set and Cromer set No.3.............................................................................................48 4-4 Ambient conditions and run times for two similar days for Cromer cycle configuration but with different airflows.............................................................54 A-1 Summary of all the data sets processed....................................................................63 B-1 Uncertainty of experimental measurements.............................................................67 B-2 Average uncertainty..................................................................................................70 B-3 Uncertainty of calculated values...............................................................................70 B-4 Calculated values......................................................................................................71 v

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LIST OF FIGURES Figure page 3-1. Test house...................................................................................................................14 3-2. Location of the combined temperature and RH sensors............................................16 3-3. Reference house.........................................................................................................17 3-4. Laminates design.......................................................................................................19 3-5. The experimental wheel assembly.............................................................................20 3-6. The experimental setup..............................................................................................21 3-7. The pulley and the driving belt..................................................................................22 3-8. Mechanism for monitoring number of desiccant wheel revolutions.........................23 3-9. Desiccant wheel power supply layout......................................................................23 3-10. Condensate measuring equipment..........................................................................24 3-11. Condensate measuring vessel and valve..................................................................25 3-12. Layout of the data acquisition system.....................................................................26 4-1. Indoor temperature and RH profiles from Baseline set. ..........................................30 4-2. Indoor temperature and RH profiles for Baseline set and Cromer set No.1. ...........36 4-3. Comparison of performance characteristics..............................................................37 4-4. Psychrometric chart for similar days.........................................................................38 4-5. Psychrometric chart for similar days.........................................................................39 46. Indoor temperature and RH profiles for Baseline set and Cromer set No.2.............44 4-7. Comparison of performance characteristics..............................................................45 4-8. Psychrometric chart for similar days.........................................................................46 4-9. Psychrometric chart for similar days.........................................................................47 vi

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4-10. Indoor temperature and RH profiles for Baseline set and Cromer set No.3. .........50 4-11. Comparison of performance characteristics. .........................................................51 4-12. Psychrometric chart for similar days.......................................................................52 4-13. Psychrometric chart for similar days.......................................................................53 4-14. Indoor temperature and RH profiles for Cromer cycle with different flow rates. .56 4-15. Comparison of performance characteristics. ..........................................................57 4-16. Psychrometric chart for similar days.......................................................................58 4-17. Psychrometric chart for similar days.......................................................................59 D-1. Latent cooling vs. RH in...........................................................................................78 vii

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LIST OF ABBREVIATIONS AC Air conditioning amb. Ambient ASHRAE American Society of Heating, Refrigerating and Air-Conditioning Engineers ARI American Refrigeration Institute Cond. Condensate EER Energy efficiency ratio (ratio of cooling in Btu/h to the power input in W) h Enthalpy [kJ/kg] in Inside lat Latent LHR Latent heat ratio .m Mass flow rate of air [kg/h] NTU Number of transfer units .Q Cooling [kJ/h] rph Revolutions per hour Ref.H Reference house RH Relative humidity [%] SEECL Solar Energy and Energy Conversion Laboratory sens Sensible SHR Sensible heat ratio viii

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T Temperature [ o C] TH Test house UMF Uncertainty magnifying function U Uncertainty Subscripts lat Latent sens Sensible ix

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Abstract of Thesis Presented to the Graduate School of the University of Florida in Partial Fulfillment of the Requirements for the Degree of Master of Science FIELD STUDY OF THE ROTARY DESICCANT SYSTEM USING THE CROMER CYCLE By Bronislava Veltcheva May 2003 Chair: Yogi Goswami Major Department: Mechanical and Aerospace Engineering The main objective of this study is to test (under field conditions) the feasibility and effectiveness of the Cromer cycle. When cooling a space to a comfortable condition there are two types of loads to be removed: the temperature-associated load (sensible load) and the moisture-associated load (latent load). Conventional vapor-compression air-conditioning systems perform well when the latent load is 25% of the total load or less. In many applications (such as geographical locations with hot and humid climates, restaurants, supermarkets, etc.) the latent load often is higher. In such cases, the conventional air conditioning system fails to meet the increased latent load. The Cromer cycle uses a desiccant for enhanced dehumidification of the air. It is based on installation of a desiccant wheel to transfer heat and moisture between the return and supply side of an air handler. The unique feature of the Cromer cycle is that regeneration of the desiccant is accomplished by the return air (not by an external heat source). x

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To test the Cromer cycle under field conditions, the existing air-conditioning system of a residential house was retrofitted to accommodate a desiccant wheel. The wheel was alternately switched in and out of the system. Data for the performance of the system were collected and compared for the standard and the Cromer configurations. To screen out any changes due to the ambient conditions only, another house located close to the Test house was also instrumented and monitored. xi

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CHAPTER 1 INTRODUCTION Air conditioning (AC) is the process of providing by mechanical means control of temperature, relative humidity, movement and purity of the air. Maintaining a space at a desired indoor condition may be achieved by simple heating (increasing the dry bulb temperature), simple cooling (lowering the dry bulb temperature), humidifying (adding moisture), or dehumidifying (removing moisture) the air. Quite often two or more of these processes are required to bring a space to the desired condition. To maintain the desired comfort conditions an air conditioning system has to handle two loads. These are the temperature associated, or sensible load and moisture associated, or latent load. The sensible load is met simply by changing the dry bulb temperature of the air. To meet the latent load of the space some moisture has to be added or removed from it. There are four principal methods [Jones 2001] of dehumidification: Cooling air to a temperature below its dew point Adsorption Absorption Compression followed by cooling. The conventional vapor-compression AC system meets the latent load of the space by cooling the air below its dew point and as a result water vapor is condensed from the air. 1

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2 1.1 Why Air Conditioning Air conditioning has grown rapidly around the world. As shown in Table 1-1 [Energy Information Administration 2000] in the last twenty-five years more Americans have air conditioners in their homes and use their AC equipment more often. Furthermore nowadays almost all automobiles are equipped with AC systems. Table 1-1. Use of air conditioning equipment in the USA households (percent of households) Survey year Number of households (million) Percent with central air conditioning Percent with window/wall air conditioning Percent with no air conditioning National 1978 76.6 23.0 32.8 44.2 1979 77.5 24.1 30.7 45.1 1980 81.6 27.2 30.0 42.8 1981 83.1 26.9 31.3 41.8 1982 83.8 27.9 30.2 41.9 1984 86.3 29.7 29.9 40.4 1987 90.5 33.9 29.8 36.4 1990 94.0 38.9 28.8 32.3 1993 96.6 43.5 24.9 31.6 1997 101.5 47.1 25.4 27.5 South 1978 24.6 36.9 37.7 25.5 1979 24.9 38.5 33.8 27.7 1980 27.0 41.4 32.7 26.0 1981 27.7 42.6 34.0 23.4 1982 28.1 42.1 33.7 24.2 1984 29.3 47.3 29.8 22.8 1987 30.9 52.3 29.9 17.9 1990 32.3 59.0 28.2 12.9 1993 33.5 65.1 24.1 10.8 1997 35.9 69.7 23.2 07.0 Energy Information Administration (EIA), 2000. URL: http://www.eia.doe.gov/emeu/consumptionbriefs/recs/actrends/recs_ac_trends.html In most commercial and residential applications, the humidity in the space is not directly controlled. Rather it is controlled only indirectly; and increases or decreases as a result of changes in the match between the sensible and latent capacity of the AC

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3 equipment compared to the sensible and latent loads of the space. A conventional AC equipment performs well when sensible load is 75% of the total cooling load or higher [Kosar et al.1998, p.72]. There are many applications, however, where the latent load is higher than 25%. Geographical locations such as Florida, where the weather is hot and humid for many months throughout the year; supermarkets with big display cases; and restaurants are among those applications. In such cases, the conventional AC unit often fails to meet the comfort conditions. This results in elevated indoor humidity levels, discomfort, and mold and mildew growth. 1.2 Desiccant Cooling Concept Use of desiccants is one solution to the problem of high humidity. Desiccants are materials that have an affinity for water. While conventional AC equipment controls humidity by condensation on a cold surface, desiccant-based systems dehumidify by adsorption or absorption in a hydroscopic material. The process of attracting and holding moisture is described as either adsorption or absorption, depending on whether the desiccant undergoes a chemical change as it takes on moisture. Adsorption does not change the desiccant, except by the addition of the mass of water vapor; it is similar to a sponge soaking up water. Absorption, on the other hand, changes the desiccant chemically or physically. Two basic types of desiccants are used: solid desiccants (e.g., silica gels, zeolites and synthetic polymers) and liquid desiccants (e.g., salt solutions and glycols). All desiccants function by the same mechanism transfer of moisture due to a difference between the water vapor pressure at desiccant surface and the surrounding air. The vapor pressure of water at the desiccant surface depends on the physical characteristics of the

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4 desiccant, the temperature of the desiccant, and the amount of water adsorbed in the desiccant. When the vapor pressure at the desiccant surface is lower than that of the air, the desiccant attracts moisture. When the surface vapor pressure is higher than that of the surrounding air, the desiccant releases moisture. Equilibrium is reached when the vapor pressure in the desiccant is equal to that in the air. To allow repeated use of the desiccant, it has to be regenerated. Regeneration usually is accomplished by heating the desiccant using an external heat source. Most desiccant cooling systems use a desiccant to handle the latent load before air goes to the cooling device. The desiccant material picks up moisture from the air before the air is sensibly cooled. This way it is not required to cool the air excessively in order to condense moisture from it. The literature provides extensive overviews of work showing the effectiveness and energy-saving potentials of desiccants [Pesaran et al. 1992, Oberg 1998, Mago and Goswami 2001].

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CHAPTER 2 CROMER CYCLE The Cromer cycle is a desiccant-based technology for enhanced dehumidification of the air. It is based on installing a desiccant wheel between the return and supply air streams in an AC system to transfer heat and moisture between the two streams. Unlike other desiccant-assisted cooling technologies, the Cromer cycle does not require external heat source to regenerate the desiccant, but relies on inherent vapor-pressure differential. A general layout of an air handler equipped with the Cromer cycle is shown in figure 2-1. A schematic of the wheel operation is given in figure 2-2. The processes that air undergoes when passing through the wheel are as follows: cold air with very high relative humidity (RH) leaves the cooling coil and passes through the working side of the wheel, cooling the desiccant and transferring moisture to it. At the same time, the warmer air with lower RH from the conditioned space passes through the return side of the wheel, absorbing moisture and regenerating the desiccant. The release of moisture into the air returning from the space before it enters the cooling coil increases the latent ratio of the coil, enhancing its dehumidification abilities. The RH and temperature difference of the two air streams provides the potential for moisture transfer. The feature of Cromer cycle technology that distinguishes it from other desiccant-based concepts is that the return air (rather than an external heat source) accomplishes regeneration of the desiccant. To show the differences in the cooling process between the standard AC cycle and the Cromer cycle, the corresponding state points of the air are shown on a Psychrometric chart (Figure 2-3). 5

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6 Supply Air Return Air Desiccant Wheel Air Handler Wheel Motor Figure 2-1. General layout of the AC handler equipped with the Cromer cycle Cooled and humidified air to air handler Warm and low RH air from space Slightly warmed and dehumidified air to space Cold and high RH air from air handler Working side Regeneration side Figure 2-2. Desiccant wheel operation

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7 Point 1 is the state point of the air that returns from the conditioned space. For the standard air conditioner configuration, the air at state 1 enters the cooling coil where it is cooled down and dehumidified. Point 4" depicts state of the air as it leaves the coil. This point represents the temperature and moisture content of the air that is supplied to the conditioned space by the standard AC system. The Cromer cycle is depicted in the same figure with the solid line passing through points 1 to 4. The desiccant adsorbs 20 2 4 3 4 1 5 10 15 4 c Temperature [oC] 4 s Figure 2-3. Psychrometric chart of standard AC cycle and the Cromer cycle. 1 = return air, 2 = air before cooling coil, 3 = air after cooling coil, 4 = supply air (Cromer cycle), 4s and 4c = calculation points, 4 = supply air (standard configuration) moisture from the cold and high RH air leaving the coil. This sorption of moisture dries the supply air before it goes to the space, and follows the line between state points 3 and 4. The moisture adsorbed by the desiccant is then re-evaporated into the return air before it reaches the cooling coil. The process between state points 1 and 2

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8 represents this process that also regenerates the desiccant. The process between points 2 and 3 depicts the work performed by the evaporator cooling coil. 2.1 Parameters That Impact Cromer Cycle Performance The desiccant wheel is the heart of the Cromer cycle. There are number of parameters that have significant impact on the performance of the wheel and from there on the Cromer cycle. Zhang and Niu [2002] found three key parameters: Desiccant isotherm shape Maximum desiccant matrix moisture uptake Heat and mass transfer characteristics of the matrix. Depending on these parameters but as well as on the operation conditions, the best for the corresponding application geometry of the wheel, size of air passage channels, air flow rate and speed of rotation can be chosen. 2.1.4 Solid Desiccant Materials Isotherm Shape Adsorption behavior of the solid desiccants depends on: Total surface area Total volume of capillaries Range of capillary diameters. A large surface area gives the adsorbent a larger capacity at low relative humidities. Large capillaries provide a high capacity for condensed water, which gives the adsorbent a higher capacity at high relative humidities. A narrow range of capillary diameters makes the adsorbent more selective in the vapor molecules it can hold. The desiccant isotherm characterizes how a desiccant material picks up moisture at different levels of RH. Different desiccant materials exhibit different isotherm shapes. Since the

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9 adsorption behavior of the solid desiccants depends on the surface characteristics of the desiccant and the geometry of the internal structure, they can be engineered and manufactured to produce a variety of isotherm shapes. Figure 2-4 [ASHRAE 1997] illustrates this point using three silica gels adsorbent materials. Figure 2-4. Adsorption characteristics of some experimental silica gels (ASHRAE Fundamentals1997, Fig.6, p.21.4) The Cromer cycle application requires the desiccant to adsorb moisture from air coming off the coil that is cold and close to saturation and desorb moisture to air that is warmer and at a lower RH. The desiccant is regenerated by the vapor pressure differential inherent in the RH differences rather than heat or temperature difference. Therefore, desiccant materials with isotherms similar to that of Gel 1 (Figure 2-4) are required.

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10 2.1.2 Desiccant Matrix Moisture Uptake Desiccant matrix moisture uptake is defined as the moisture adsorbed by a desiccant at 100 % RH per unit mass of desiccant material. The larger the maximum desiccant moisture uptake, the longer the adsorption and regeneration process times. 2.1.3 Number of Transfer Units Larger number of transfer units (NTU) means more efficient heat and mass transfer within the desiccant wheel. The optimal performance of a desiccant wheel versus the desiccant wheel NTU is similar to the maximum desiccant moisture uptake. The adsorption-side outlet humidity decreases with NTU. Therefore the performance improves by increasing the NTU. Zheng et al. [1995b] discussed the importance of NTU and ways to modify it. 2.1.4 Speed of Rotation The rotational speed of a desiccant wheel is the number of rotations that it undergoes per unit time. This speed determines the length of time the desiccant stays in the adsorption process as well as the length of time it is regenerated. Many authors note that wheels used for air dehumidification are more sensitive to the speed of rotation compared to those for enthalpy recovery. The desiccant wheel must be operated at a optimum rotational speed to maximize the dehumidification performance and therefore the rotational speed is a critical parameter for optimization [Zheng et al. 1995a]. Depending on the application and the parameters of the wheel the correct speed is to be found to provide the optimum heat and mass transfer. When a desiccant wheel rotates much faster than the optimum speed, the adsorption and regeneration processes are too short which results in a poor performance. Similarly if the rotary speed is lower than the optimum then the adsorption and regeneration processes are too long and more energy is

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11 wasted in sensible heating/cooling than in the sorption process and therefore is less effective. 2.2 Literature Review The main feature of the Cromer cycle that differentiates it from the conventional air conditioner is that the dew point (moisture content) of the incoming air is substantially increased by the transfer of moisture to the air before it reaches the cooling coil. An increased average coil temperature results in improved energy efficiency over prior methods of sensible heat transfer for dehumidification enhancement and in increased dehumidification over a conventional air conditioner. [Cromer 1988, p.4] There are several theoretical analyses of the cycle performance in the literature. Nimmo et al. [1993] developed a simulation model that calculates the air conditioner Energy efficiency ratio (EER) as a function of the Sensible heat ratio (SHR). They use that model to compare the performance of the Cromer cycle with that of heat-pipe-augmented, single-speed air conditioner and an air conditioner with a variable speed supply air fan. The simulation results indicate feasibility of the cycle. When compared to the other dehumidification alternatives, the Cromer cycle maintains a higher EER over a wide range of SHR values. Rengarajan and Nimmo [1993] carried out a parametric study. First the authors compare the energy use, comfort (defined as the number of hours the space conditions are within ASHRAE comfort zone) and the total cost (sum of capital costs and operation costs) for single speed air conditioners and variable speed air conditioners each assessed with and without the addition of a desiccant wheel and heat pipes. The results from the parametric study show that the AC equipped with Cromer cycle provides better comfort

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12 at low energy use and at a lower total cost. Furthermore the authors evaluate the energy saving potential of the Cromer cycle by comparing it to a high efficiency air conditioner. The authors show that the high efficiency AC has higher efficiency and consumes less energy than the Cromer cycle. When, however, the two are forced to maintain the ASHRAE comfort conditions for applications with high latent load for example, Miami the Cromer cycle consumes 10 percent less energy. Results from a study of the Cromer cycle bench test prototype under laboratory ARI test conditions are reported by Cromer [1997] (Table 2-1). Table 2-1 Performance of a standard AC handler compared with an AC handler with the Cromer cycle Standard AC unit AC unit with Cromer cycle Improvement % Operational capacity [Btu/hr] 53,590 66,328 23.8 Latent cooling [Btu/h] 14,017 35,425 152.7 LHR [%] 26.2 53.40 103.8 Dehumidification [gal/h] 1.56 3.93 153.2 Watts (over test hour) 6709 5610 16.4 EER 7.99 11.82 47.9 (Cromer 1997, Cromer cycle: An energy efficient solution to indoor air quality problems. Engineering Solutions to Indoor Air Quality Problems, p. 294) 2.3 Objectives of the Present Study The theoretical studies and the laboratory test results published in the literature show that for high latent load applications the Cromer cycle is significantly superior compared to the standard AC configuration. Published literature shows that the Cromer cycle technology enables the evaporator coil to meet higher latent loads and it achieves that at reduced energy consumption.

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13 If similar behavior can be verified under field conditions the system could contribute to significant energy savings, while providing better indoor conditions. The purpose of this study was to test the feasibility and effectiveness of the Cromer cycle technology under field conditions. To test the performance of the Cromer cycle in field conditions the following was done: Two residential houses, located close to each other were equipped with the necessary instrumentation. The existing residential AC system of one of the houses, called Test house, was retrofitted with the Cromer cycle equipment, while the AC system of the second house, called the Reference house, was kept in the standard vapor-compression configuration; The Cromer equipment was alternately switched in and out of the AC system of the Test house. Data for the performance of the AC unit in its standard configuration and with the Cromer cycle attached were collected; Indoor conditions maintained in the Test house by the AC in its standard configuration and with the Cromer equipment were compared; Several performance characteristics as Q total, Q sensible, Q latent, LHR and apparent energy efficiency ratio were calculated and compared for the standard and the Cromer configurations in the Test house.

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CHAPTER 3 EXPERIMENTAL SETUP For the purposes of the present study an existing residential air conditioning unit, located in the Solar House in the Solar Energy and Energy Conversion Laboratory (SEECL), Gainesville, Florida was chosen. A number of developments that are now used worldwide originated there. As recognition of their important role the SEECL and the Solar House were designated as a Mechanical Engineering Heritage Site in January 2003. 3.1 Experimental Facility The Solar house (figure 3-1) has 0.23m hollow concrete block walls, a double wood floor and an asphalt shingle roof. The house encloses approximately 110 m 2 of Figure 3-1. Test house 14

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15 living space and is orientated East-West. There is no additional insulation added on the walls. There is fiberglass bat, R-11 insulation over the conditioned space. The AC distribution duct system of the house is located in the attic, directly above the conditioned space. The conventional AC system in the Solar house is a vertical GrandAire three ton high efficiency air conditioner condenser unit model GS3BA-036KA with matching GrandAire air handler GB3BM-036K-A-l0 model. This is a direct expansion R-22 AC system. 3.2 Measuring Instrumentation For the objective of the study, the Test house, thereinafter interchangeably referred as Solar house or Test house, was instrumented with measuring devices to monitor and record the desired variables. Temperature and RH measurements were provided by combined sensor transmitters, manufactured by Vaisala Co. HMD60W sensor/transmitter was used to measure the inside RH and temperature. Ambient conditions were monitored by HMD60YO. HMD60Y sensors were used to measure the corresponding temperatures and relative humidities of the return air before the desiccant wheel and the AC handler and of the supply air at the exit of the AC handler and after the wheel. A schematic of the sensors locations in the duct system is given in figure 3-2. All Vaisala sensor/transmitters were installed with the factory calibration, specified to be .3 o C for the temperature readings and % for the RH readings. Periodically, however, the outside RH sensor was recalibrated because of problems with condensate formation.

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16 1 2 3 4 Figure 3-2. Location of the combined temperature and RH sensors Energy consumption of the AC unit was measured using watt-hour transducer Model WL40R-052, manufactured by Ohio Semitronics Inc, Ohio. Energy consumption of the wheel was measured separately using a watt-hour transducer Model WL40R-049, manufactured by the same company. Both transducers were installed with the factory calibration which is specified to be .5% of full scale. The pulse pick up of the watt-hour transducers provides a pulse for every 10Wh consumed. Air flow measurements were provided by using a hot wire anemometer, manufactured by Comark Ltd. Its accuracy is specified to be % of the reading. A data acquisition system based on LABTECH software was setup to acquire the signals from the corresponding measuring equipment. A program was designed to scan each probe every 5 seconds, then the readings were averaged for each 20-second-period and recorded in a file. Another house, named the Reference house for this study located next to the Test house, was monitored to be used as a control. Though the reference building (figure 3-3), is located very close to the Test house, it is not the same. It is larger

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17 approximately 180 m 2 (as compared to 110m 2 test house), oriented North-South, has different glass area and uses 3 ton Trane condenser and air handler. Figure 3-3. Reference house Despite the differences, however, when the indoor conditions of the two houses were compared it was established that the humidity levels maintained by the corresponding conventional AC systems were quite similar. Therefore it was decided that this Reference house could serve as a control for the purposes of the study. Since the ambient conditions vary, collecting data from this Reference house would provide an additional control comparison. Monitoring simultaneously the Reference house, where no changes are made and the Test house would make it possible to estimate to what extent the different comfort conditions maintained in the Test house with the Cromer technology, are due to enhancing the AC unit with the Cromer equipment as opposed to the changes in the ambient conditions. If with the Cromer cycle considerable decrease in

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18 the RH levels is observed but the same trend is observed in the Reference house also then the reason could be favorable ambient conditions rather than the Cromer equipment. If however, in the Test house considerable changes in the indoor conditions are observed between the standard configuration and the Cromer cycle while in the Reference house the indoor conditions are maintained the same, then it could be concluded that the changes were due to the Cromer cycle. The Reference house was equipped with HMD60W sensor/transmitters for monitoring the inside temperature and RH and with a WL40R-052 watt-hour transducer for the AC energy consumption measurement. The monitoring system of the Reference house was connected to the data acquisition system of the Test house. 3.2 Desiccant Wheel The desiccant wheel, used in the present study, was manufactured by AirXchange Company, Rockland, MA. It was 0.075m wide, 0.94m diameter and consisted of 6 removable segments. 3.2.1 Desiccant Material In the study two types of desiccants, called Desiccant A and Desiccant B, were tested. The first test was conducted with Desiccant A material the typical enthalpy wheel desiccant that AirXchange company uses for their enthalpy wheel products. The desiccant wheel had flat laminate segments structured in an ideal parallel plate geometry. The laminates were arranged continuously with one flat and one structured layer (Figure 3-4 (A)). The structured layer had small conical internal dimples to separate the laminates and define the geometry of the matrix. For the second and the third test the segments were replaced with laminates that were not flat but waved. The waved

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19 Figure 3-4. Laminates design. (A) Flat laminates. (B) Waved laminates. segments had axial ridges (Figure 3-4 (B)) to determine the geometry while providing an obstruction for the air carryover from one side of the wheel to the other. The new segments laminates were coated with different silica gel, called desiccant type B. The second desiccant type was suggested by Dr. Cromer. Under laboratory conditions the inventor had tested several types of desicc ants and found type B one to have superior performance for Cromer cycle applications. 3.2.2 Speed of Rotation In the current study the Cromer cycle pe rformance was tested with the desiccant wheel rotating at two different speeds: 10 revolutions per hour-a speed of rotation found to be the optimal in theoretical simulations [Nimmo et al. 1993]. It is to be admitted, though, that this rotational speed was found optimal for a different desiccant type; 42 revolutions per hour-determined by Dr. Cromer, based on laboratory tests of a desiccant wheel with segments, co ated with type B desiccant.

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20 3.2.3 Wheel Accommodation Since desiccant wheel transfers moisture between the return and supply air streams, the important moment in retrofitting an existing AC system with the Cromer cycle is to reorient the air in order to direct the air flow through the wheel (Figure 3-5). Figure 3-5. The experimental wheel assembly The original setup of the air handler in the Solar house in the standard AC configuration was that the air handler was taking return air directly from the space being

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21 conditioned via a short straight duct connected to a return air grille. Another short and straight duct connected the air handler supply side to a plenum box from which a spider type distribution system brought the air to each room of the house. In its standard Figure 3-6. The experimental setup

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22 configuration the existing vertical air-handling unit in the Solar house fitted in 1x1x2m (length by width by height) space. In order to connect the wheel without modifying the distribution system, but at the same time to avoid any sharp turns, the retrofitted configuration took a 3.5x1.5x3m space (Figure 3-6). There was information that in previous tests certain slipping had been observed (the belt that drives the wheel skided on its surface, thus changing its speed of rotation). In order to avoid that, in this study the flat belt that originally came with the wheel was replaced by a grooved belt (Figure 3-7). Figure 3-7. The pulley and the driving belt A mechanism (Figure 3-8) was designed for monitoring the number of rotations of the desiccant wheel. Tests showed that with the new belt the problem of the belt slipping on the wheels surface was eliminated.

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23 Figure 3-8. Mechanism for monitoring number of desiccant wheel revolutions 3.2.4 Power Supply of the Desiccant Wheel The desiccant wheel is supposed to rotate only when air is blowing in the AC system. This requirement was achieved by connecting the motor of the wheel to the power supply via a relay as shown in the Figure 3-9. Rela y Blower Motor 240V/AC From Control FUSE 120V/AC N eutral Rela y Wheels Electric Motor 120V/AC Line Figure 3-9. Desiccant wheel power supply layout

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24 3.3 Condensate Measuring Equipment During the field study it was recognized that it would be useful to measure automatically the water condensed by the cooling coil. For the purposes of the present test, a system was designed to measure the volume of the condensed water. The schematic of the system and a picture of the condensate collecting part are given in figures 3-10 and 3-11 respectively. The equipment was connected to the data acquisition system and was designed to send a pulse for each 110ml of water removed by the cooling coil. Magnet N S FUSE 120V/AC N eutral Rela y Timer Water Level Level Sensor Solenoid Valve 120V/AC Figure 3-10. Condensate measuring equipment 3.4 Data Acquisition System A data acquisition system (Figure 3-12) based on LABTECH software was setup to acquire the signals from the corresponding measuring equipment. The program was designed to scan each probe every 5 seconds, then the readings were averaged for each 20-second-period and recorded in a file. Since all variables were recorded at each 20

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25 second-period, data collected are very detailed and made it possible to obtain information about beginning and end of each cycle, its duration, state points of the air before and after the wheel both on its working and regeneration side, condensate removal, and the exact energy consumption. Figure 3-11. Condensate measuring vessel and valve

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26 Figure 3-12. Layout of the data acquisition system +17V DC +17V AC I = 4-20 mA Us = 1 5V 4mA = Log.0 20mA = Log.1 Digital Signals Analo g Si g nals 4mA / 20mA +17V Current to TTL Converter I In3 In1 2 1 .4 TTL Level 4-20mA +17V Pr ob e In 8 In.1 C o m p. B U S D ata Acquisition System Data Address Counter Control Logic ADC GainAmp. M U X

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CHAPTER 4 PROTOCOL AND EXPERIMENTAL RESULTS 4.1 Protocol An experimental protocol was developed to study operation of the AC system when retrofitted with the Cromer cycle equipment. It has to be noted that no attempt was made to achieve operation under ARI conditions. The goal was to test the performance of the Cromer cycle in field conditions. All data, collected for the periods of operation of the air handler as a conventional AC unit, were collected in a baseline set. The data for the periods, when the AC system was enhanced with the Cromer cycle, were collected in the Cromer set. Cromer set includes several data sets because Cromer technology was tested with different desiccant types and at different speeds of rotation of the desiccant wheel. The protocol involved alternate switch of the Cromer equipment in and out of the AC system of the Solar house. Since ambient conditions change alternated switch made it possible to obtain data both for the baseline set and for the Cromer set under variety of ambient conditions. As already mentioned in Chapter 3, during the first test the wheel was rotated at 10 rph, a speed found to give optimum performance for the Cromer cycle under computer simulations [Nimmo et al. 1993]. The second test was conducted with the wheel rotating at 42 rph, a speed that the inventor found to be the optimum under laboratory test of a wheel, covered with type B desiccant. For the third test conducted with the second wheel and type B desiccant, the speed of rotation was reverted back to 10 rph in order to check 27

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28 how it would influence the overall performance and if this would reduce the heat recovery from what was observed in the preceding test. Before the beginning of each field test, the system was run in its standard vapor-compression configuration. For the first test the thermostat was set at 22 o C and the blower was set at low speed. The baseline test was run for a week. After that the Cromer cycle equipment was installed. The Cromer technology was tested with the desiccant wheel, consisting of flat laminate segments, coated with desiccant type A and with a wheel rotation speed of 10 rph. The tests were conducted for a two-week period and under the same settings as the preceding baseline test. The data were collected in the Cromer set and stored as set No.1. For the next test the Cromer configuration was disconnected and data collected for the operation of the AC system in its standard configuration again. The test was conducted for two weeks, the thermostat set at 24 o C and the blower speed at medium. After this two-week period, the Cromer cycle was connected again. This time, however, the performance was tested with waved laminate segments, coated with desiccant type B and at a speed of rotation of 42 rph. Under the settings of 24 o C and medium fan speed the test was run for a two-week period and the data collected in the Cromer set as set No.2. The next step was to switch the Cromer configuration out of the system for 10 days so as to collect more data for the baseline set. After this 10-day-period the Cromer configuration was connected in the system again. The new test was conducted for 4 weeks. During this test the settings, as well as the desiccant wheel, were the same as in

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29 set No.2 tests. The only difference was that the rotational speed of the wheel was reverted back to 10 rph. Data from this test were stored in the Cromer set as set No.3. Appendix A contains tables for all data sets collected. Each table presents summarization of the ambient conditions, duration of operation, condensate removal and energy consumption of the corresponding AC systems in the Test house and in the Reference building. The detailed data sets include extended tables for every day. These extended tables give information about the ambient conditions, the indoor conditions, temperatures and relative humidities at different places of the return and supply air ducts, number of cycles of operation, duration of each cycle, condensate removed by the coil and energy consumption of the AC units both in the Solar house and in the Reference building. These detailed tables are available on a compact disk. 4.2 Experimental Results 4.2.1 Baseline Set AC Unit in Standard Configuration Data, collected during the periods when the AC system in the Solar house was operating in a conventional cycle, are presented in the baseline data set and used for comparison. Plots of the typical indoor RH levels maintained in the Solar house and in the Reference building during the periods when the AC systems in both houses were operating in the standard vapor-compression configuration are illustrated in figure 4-1. As indicated, despite the differences between the size of the two houses and the different AC equipment, the inside RH levels maintained in the Test house were found to be similar to the inside RH levels maintained in the Reference house, and somewhere in the range of 45-50%.

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2030405060701357911131517192123Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] 30 Figure 4-1. Indoor temperature and RH profiles from Baseline set. (A) 09/18/2001. (B) 09/20/2001. (C) 06/10/2002. (D) 08/05/2002.

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31 4.2.2 Set No.1 Cromer Cycle Configuration with the Desiccant Wheel Using Flat Laminate Segments and a Rotational Speed of 10 rph The immediate observation, after conducting this first test of the retrofitted AC system, was that installation of the desiccant wheel introduced a considerable increase of the pressure drop in the AC system. This resulted in 35% decrease in the airflow rate (the mass flow rate dropped from 1680 kg/h down to 1080 kg/h). Another observation was that with the wheel in place there was an increase in the average operational time of the air conditioning system. Since in Cromer configuration the desiccant wheel transfers moisture and heat between the high pressure side and the low pressure side of the wheel, with the radial and flat design of the laminates a significant re-circulation of air from supply to the return side of the wheel was observed. Physically it was easy to feel this re-circulation but it was not quantified mathematically. Calculations were conducted to quantify the amount, but because of the considerable uncertainty involved, no precise value could be given. With regard to the ability of the retrofitted AC system to improve the indoor conditions, this data set is not very persuasive. Most of the time the Cromer cycle system was maintaining indoor relative humidities in the range of 45-50% as did the conventional arrangement. There were days though, when for a limited time during the day the inside RH levels were below 40%. Review of the data shows that these were the days when the AC system was operating for more than 5 hours a day. It was felt that the reason for the inconclusiveness of any enhancement of performance by the Cromer cycle was because the tests were conducted in the month of October when the ambient temperatures were lower. The thermostat setting was satisfied for longer periods and under these circumstances run-time fraction of the air conditioner was low.

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32 For more detailed evaluation of the AC performance, pairs of days with similar ambient conditions from the baseline set and the Cromer set were chosen and compared. Days in each pair were chosen based on meeting the following criteria: Ambient conditions within each pair were very similar Average ambient temperatures were high throughout the day. The following parameters were calculated: Total cooling capacity 41hhmtotal Q [kJ/h] (4-1) Sensible cooling capacity 44'hhmQsensible [kJ/h] (4-2) Sensible heat ratio totalsensibleQQSHR (4-3) Latent cooling capacity '41hhmQlatent [kJ/h] (4-4) Latent heat ratio totallatentQQLHR (4-5) Apparent energy efficiency ratio 1 PowerInputQEERapptotal WhBtu/ (4-6) where h 1 h 4 and h 4' (Figure 2-3) are the enthalpy of the return air, enthalpy of the supply air and enthalpy of a condition when the air is at the temperature of the return air but with the humidity ratio of the supply air. The symbol is used for the mass flow rate of the air. m As an illustration, the results for two such pairs are presented. The ambient conditions during those pairs of days, the corresponding run times of the systems in the 1 The energy efficiency ratio is defined as Total cooling/Power input under standard ARI conditions. Here EER was estimated under field conditions, therefore it was called EERapp.

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33 two houses monitored and the condensate removed by the air handler in the Test house are shown in table 4-1. Table 4-1. Ambient conditions and run times for the data pairs from the baseline set and Cromer set No.1 Date A T amb >25 o C B T amb >28 o C C RH amb. D TH duration E Ref.H duration F Condensate hours o C hours o C % hours hours liters Baseline 09/17/01 9:50 28.24 6:15 28.74 53.28 6:04:40 9:55:40 21.9 Cromer 10/05/01 10:10 28.79 6:55 29.85 55.09 7:42:38 8:36:19 25.2 Baseline 09/19/01 12:00 28.62 7:10 29.05 65.59 9:13:40 11:45:40 24.6 Cromer 10/06/01 11:35 28.28 6:35 29.42 71.10 10:46:40 10:02:43 30.3 A = Time when ambient temperature was above 25 o C. Left sub column denotes number of hours ambient temperature was above 25 o C. Right sub column denotes the average ambient temperature during that time. B = Case where ambient temperature was above 28 o C. Left sub column denotes number of hours ambient temperature was above 28 o C. Right sub column denotes the average ambient temperature during that time. C = Average ambient RH during the time of day when the ambient temperature was above 25 o C. D = Duration of operation of the AC unit in the Test house. E = Duration of operation of the AC unit in the Reference house. F = Amount of water removed from the air by the AC coil in the Test house. Cromer cycle resulted in more water removal from the air. The average operational time, however, was increased. Data show that, when the systems in the Solar house and in the Reference house were both in standard configuration, on average it took 30% longer time for the air conditioner in the Reference house to meet the thermostat setting. When, however, the Cromer equipment was installed in the Solar house, this

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34 difference in the operational times was reduced. Furthermore, days were observed when the operational time of the AC system in the Test house was longer than the corresponding time in the Reference house. Comparison of the temperatures and relative humidities, maintained in the Solar house and in the Reference house are given in figure 4-2. The calculated performance parameters for the AC system in the Solar house are presented in a graphical form in figure 4-3. Each point on the plots represents the average for one run period of the AC unit. It has to be noted that since the sensor used to measure the temperature and RH after the coil was located after the fan, the measurements include the additional heat generated by the fan motor. Therefore, the cooling calculated here is less than the actual cooling performed by the cooling coil. To facilitate the calculations a Fortran program for calculation of the performance characteristics was developed. The print of the program developed is given in Appendix C. The program used a link to the software package PROPATH (PROgram PAckage for THermophysical properties of fluids), courteously given for use to the SEECL by the PROPATH Group [Propath Group 2001]. The states and the corresponding cooling processes of the air in the Solar house are plotted on Psychrometric charts in figures 4-4 and 4-5. For plotting the charts an ASHRAE Psychrometric Chart software was used [Hands Down Software group 1992]. In these figures the states of the air when the system was in its standard vapor compression configuration are depicted by the symbol S, where S1 is the return air state and S4 is the supply air state. The symbol C depicts the states of the air when the AC system was modified with the Cromer equipment. The state points are also depicted by

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35 numbers 1 to 4, where depicts return air state, -state of the air after the desiccant wheel on its regeneration side, -state of the air as it leaves the AC handler, and -state of the supply air after the desiccant wheel, as depicted in figure 2-3. As illustrated in figures 4-2 and 4-3, the following observations are made for the Cromer configuration as compared to the standard configuration: Observed up to 50% increase in the latent heat ratio (latent cooling to total cooling); Observed approximately 25% increase in the latent cooling; Observed approximately 15% decrease in the total cooling performed; Observed approximately 30% decrease in the sensible cooling; Observed 15% reduction in the apparent energy efficiency ratio; and RH levels maintained in the space are slightly lower. Increase in the LHR and the latent cooling observed in the Cromer configuration test, can be explained from the fact that the desiccant wheel desorbs moisture into the return air before it reaches the coil. Therefore the air is wetter and closer to its dew point, which switches the total cooling toward more latent cooling. The observed decrease in the sensible cooling could be explained from the reduced inlet air temperature and the reduced air flow due to the desiccant wheel. The desiccant wheel reduces the temperature of the air before it reaches the cooling coil because of evaporative cooling. However, when the corresponding initial and final states of the air in the standard configuration are compared with the Cromer cycle on psychrometric chart, it is observed that the enthalpy difference between the inlet and the

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36 Figure 4-2. Indoor temperature and RH profiles for Baseline set and Cromer set No.1. (A) Baseline set-09/17/01. 2030405060701357911131517192123Time of dayT [oC] & RH [%] 20304050607013579111315171921Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] (B) Cromer set-10/05/01. (C) Baseline set-09/19/01. (D) Cromer set-10/06/01.

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37igur 4-3. Compb. (C) LHR vs RH in. 2000022000240002600028000300001720222527303235T amb [oC]Q total [kJ/h] 7.07.58.08.59.09.510.01720222527303235T amb [oC]EER [Btu/h / W ] 0.100.200.300.400.5030354045505560RH in [%]LH R 30004500600075009000105001200030354045505560RH in [%]Q lat [kJ/h] earison of performance characteristics. (A) Q total vs T amb. (B) EER vs T am F (D) Q lat.vs RH in.

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Figure 4-4. Psychrometric chart for similar days (Baseline set, 09/17/01 Cromer set No.1, 10/05/01) 38

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Figure 4-5. Psychrometric chart for similar days (Baseline set, 09/19/01 Cromer set No.1, 10/06/01) 39

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40 outlet condition of the air is almost the same. The increased moisture of the air results in a wetter coil that facilitates the heat transfer thus offsetting the negative impact of the reduced air temperature on the heat transfer. Therefore the observed decrease in the sensible cooling is mostly due to the dramatic decrease in the airflow rate, caused by the introduction of the desiccant wheel. Anyway, for Cromer cycle applications it would be better if the motor of the blower is located before the cooling coil. This way the heat t of the motor would offset the pre-cooling of the air resulting from the air passing ugh the regeneration side of the desiccant wheel. Decrease in the sensible cooling exceeds the corresponding increase in the latent ling resulting in a decrease in the total cooling. Decrease in the apparent energy efficiency ratio observed can be explained with reduction of the total cooling performed by the coil. Decrease in the sensible cooling, performed by the evaporator coil, inevitably eases the operational time of the AC system. Since only the thermostat setting trols the air handler, for one and the same setting the Cromer configuration will take er time before it is able to satisfy the thermostat. Therefore the system equipped with Cromer cycle will operate longer and will have higher overall energy consumption. With the Cromer cycle in place the RH of the air in the supply ductwork is siderably lower. This way the requirement of the ASHRAE Standard 62 that calls for idity in the ducts below 70% is accomplished, something that is ly very difficult to satisfy with the conventional AC vapor compression configuration. er ducts prevent fungus and bacteria from growing so the space conditioned is at a er risk from such contamination. inputhrocoothe incrconlongthe conmaintaining the humrealDrilow

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41 4.2.3 Set No.2 Cromer Cycle Configuration with the Desiccant Wheel Using Waved Laminate Segments and a Rotational Speed of 42 rph In the Cromer set No.2 performance of the cycle was tested with new desiccant segments for the wheel. The laminates of the new segments were coated with silica gel, desiccant B type. In order to reduce the pressure drop the distance between the laminates was slightly increased. The larger air channels, however, would increase the re-circulation of the air from the high pressure to the low pressure side of the wheel. To avoid that the new laminates were not flat as in the set No.1 test but waved. After replacing the segments with the new ones and converting two of the flexible turns in the duct into rigid ones and setting the blower speed to medium small improvement in the pressure drop in the system was observed. The volume flow rate increased from 1080 kg/h to 1180 kg/h. This, however, was still below the specifications, provided by the manufacturer of the air handler. The test showed that under hot ambient conditions, the retrofitted AC unit maintains considerably lower indoor RH levels. When compared to the humidity levels with the standard configuration, it is seen that the Cromer cycle enables the conventional AC system, in hot days, to achieve and maintain approximately 20% lower indoor RH levels. Logically the more hours the unit works the more uniform the profile of the humidity maintained. This test unambiguously verified that the Cromer cycle is able to enhance the dehumidification, performed by the cooling coil. Again pairs of days with similar ambient conditions from the baseline set and the present set were chosen for more detailed comparison. Ambient conditions and duration of operation of the AC system in the Test house in its standard configuration and with the Cromer cycle for two such pairs of days are shown in table 4-2.

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42 Table 4-2. Ambient conditions and run times for the data pairs from the baseline seand Cromer set No.2 t DatooRH TH Ref.H Conden e T amb >25C T amb >28C amb. duration duration sate Baseline 06/07/02 10:05 26.93 3:0530.2376.165:53:426:25:41 18.26 Cromer 06/26/02 10:30 27.43 3:5528.6772.307:40:596:43:00 30.03 Baseline 06/09/02 11:40 27.39 5:1528.3066.864:57:186:34:40 19.47 Cromer hours oC hours oC % hours hours liters 06/27/02 11:05 27.88 6:0029.0671.117:23:386:56:21 27.17 Cromer configuration resulted in increased water removal. The average operational time of the unit, however, was also increased. Comparison betweencollected in Cromer No.2 set and the data from the Baseline set for both houses show twith the Cromer cycle the AC system in the Test house started operating at considerably longer run cycles. Furthermore, when compared the data hat to the time of operation of the AC systems the charts as shown in figures 4-8 and in the Reference house, it is seen that while under similar ambient conditionunit in the Reference house keeps its time of operation more or less the same, the retrofitted unit in the Test house increases its time of operation. Plots of the indoor conditions maintained are shown in figure 4-6. Figure 4-7 gives plots of the calculated performance characteristics of the AC system for the standard configuration and for the Cromer cycle. State points of the air and the corresponding cooling processes are plotted on psychrometric 4-9. As with the Cromer set No.1 test, here also similar positive and negative consequences are observed. Only the magnitudes are different. Following observations are made for the Cromer cycle:

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43 35% increase in the latent heat ratio %e s 30% reduction in total cooling lower energy efficiency ratio. is test if look at the latent cooling by taking the average of the data it would appear that Q lat is at the same order of magnitude for the standard and for the Cromer cncad tleaons. ons thCromer cycle maintains much lower indoor RH than the standard configuration. If tests were run when the inside RH were the same for the two configurations than the Cromer cycle would provide considerably higher latent cooling as shown by the trend lines in the corresponding plots, given in Appendix D. hile in temperature approxos heat time the system operates to satisfy the thermostat setting and from there the corrant odor was introduced in the space in the first 2 to 3 45 reduction in th ensible cooling 25% In th onfiguratio This ould le o mis ding c clusion The reas for that i at the InsideRHfQ latAn important observation that came from this series of tests was that in field conditions the speed of rotation of the wheel is very important for the heat transfer ability. At a rotational speed of 42 rph the desiccant wheel recovered more heat. WCromer set No.1 test the supply air was injected into the space at a imately 2C lower than in the standard configuration, in Cromer set No.2 the opposite was observed. This increased heat recovery is clearly illustrated on the corresponding Psychrometric charts on figures 4-8 and 4-9. Obviously the excesrecovery is undesirable for AC applications. It reduces the sensible cooling thus increasing the esponding overall energy consumption. During this test, it was observed that when the AC came on after idle periods longer than 6-7 hours, an unpleas

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44 Fig4Indoor tp Rpros for Bane aCrom.(Aase s0602. (B) Cromer set06/26/02. (C) Baseline set-06/09/02. (D) Cromer emerature andH fileseli setnd set-06/27/02. 57911192123Timf da 791113571223imef da 23456T [oC] & RH [%] T [oC] & RH [%] ure 6. 203040506070 203040506070 er set No2. ) Belinet-/07/ 315me day 3115me day 000007015791131113Tiof 13113157e oyT [oC] & RH [%] 17 92 2 203040506070157913117192123Tiof 1351191T oyT [oC] & RH [%]

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45 1800021000240002700030000330002022242628303234T amb [oC]Q total [kJ/h] 678910112022242628303234T amb [oC]EER [Btu/h / W] 0.10.20.30.40.50.6303336394245485154RH in [%]LH R 7000850010000115001300014500303336394245485154RH in [%]Q lat [kJ/h] Figure 4-7. Comparison of performance characteristics. (A) Q total vs T amb. (B) EER vs T amb. (C) LHR vs RH in. (D) Q lat.vs RH in.

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46 re 4-8. Psychromet Figuric chart for similar days (Baseline set, 06/07/02 Cromer set No.2, 06/26/02)

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47 Figure 4-9. Psychrometric chart for similar days (Baseline set, 06/09/02 Cromer set No.2, 06/27/02)

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48 minutes of its operation. This could be explained with the desiccant material picking not only moisture but other gases as well and evaporating them back. 4.2.4 Set No.3 Cromer Cycle Configuration Using Desiccant Wheel with Waved Laminate Segments and a Rotational Speed of 10 rph In this test the desiccant wheel had the same segments as in the set No.2. The only difference was that the speed of the desiccant wheel was reduced to 10 rph. This was done in order to check how the performance would change and to see if the reducerotational speed would reduce the heat recovery observed in the preceding test. Ambient conditions and duration of operation of the AC system in the Test houin its standard configuration and with the Cromer cycle for two similar pairs of days argiven in table 4-3. Table 4-3. Ambient conditions and run times for the day pairs from the baseline set an Cromer set No.3 Date T amb >25oC T amb >28oC RH amb. TH duration Ref.H duration Condesate d se e d n 2 7 9 2 nd hours oC hours oC % hours hours liters Baseline 08/06/02 16:00 27.96 12:3031.9975.3111:21:1813:58:21 32. Cromer 08/24/02 16:15 27.68 12:2531.4070.9012:56:1813:58:39 38. Baseline 08/01/02 12:30 27.06 5:0030.1376.807:05:158:20:20 22. Cromer 08/26/02 12:15 26.54 5:1529.9479.3411:49:1910:27:21 37. Comparison of the indoor RH maintained and the AC system performance characteristics for the two pairs of similar days are shown graphically in figures 4-10 a4-11. The corresponding states of the air and the cooling processes are plotted on psychrometric charts and given in figures 4-12 and 4-13

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49 When performance of the retrofitted air handler in the Cromer set No.3 tests is compared to the standard configuration under similar ambient cond itions, the following is Increased dehumidification of the space -15% to 20% lower indoor RH levels are inutes of the AC system operation in the Cromer configuration after Discussion As it was mentioned earlier, the main problem wCithClheoease in the pressure drop, which reduces the ate mmrfoe ceriiinter question thatredis rh iwourfhantirfebe pedher t witt. An attempt was made to address this question. The air intake section connected to the Cromer, reased tandard configuration. observed: maintained; 20% increase in the latent heat ratio; 20% decrease in the sensible cooling; 20% decrease in the total cooling; 15% decrease in the energy efficiency ratio. During this test again unpleasant odor was introduced in the conditioned space during the first few m longer idle periods. 4.3 ith retrof itting an A system w the romer cyc e equipm ent is t enorm us incr ir flow ra and fro there any pe rmanc haract stics deter orate. An esting was no t answe in th esearc s how ld the pe ormance c ge if he same a low rat could rovid with t Crome equipmen in place as hout i unit was removed in order to allow the return air to enter the wheel directlysome flexible duct connections were replaced with rigid ones and the sections after the AC handler and after the wheel were extended and widened. All these changes incthe air flow rate to about 10% below the flow rate in the s

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50Figure 4-10. Indoor temerature and RH profet 3. (A) Baseline set-08/06/02. (B) Cromset08/24/02. (C) Baseline set-08/01/ set-08/26/02. piles for Baseline set and Crom02. (D) Cromer 13511151912Ti of d 13511517191Ti of er sNo. 4050605 er 1 13 20304050607079137123meayT [oC] & RH [%] 20304050607079131223medayT [oC] & RH [%] 2030701311519223e ayT [oC] & RH [%] 203040506070135791113151922Time of dayT [oC] & RH [%] 7 9 11Tim 3of d 17 17

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51 200002200024000260002800030000320002022242628303234T amb [oC]Q total [kJ/h] 678910112022242628303234T amb [oC]EER [Btu/h / W] 0.150.20.250.30.350.425283033353840434548RH in[%]LH R 500060007000800090001000025283033353840434548RH in [%]Q lat [kJ/h] Figure 4-11. Comparison of performance characteristics. A) Q total vs T amb. (B) EER vs T amb. (C) LHR vs RH in. (D) Q lat.vs RH in.

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52 Figure 4-12. Psychrometric chart for similar days (Baseline set, 08/06/02 Cromer set No.3, 08/24/02)

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53 Figure 4-13. Psychrometric chart for similar days (Baseline set, 08/01/02 Cromer set No.3, 08/26/02)

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54 A new test, called the trial test, was run. Unfortunately weather deteriorated soon after the beginning of those test. As a result very limited data were obtained. Ambient conditions, operational times and water removal for selected similar pairs of days from Cromer set No.3 and the trial test are given in table 4-4. With the increased air flow in the trial test decrease in the duration of operation and in the condensate removal is observed. Indoor temperature and RH profiles are shown in figure 4-14. Comparisonthe calculated performance characteristics of the AC system in Cromer configuration with different air flows is shown in figure 4-15. Table 4-4. Ambient conditions and run times for two similar days for Cromer cycle configuration but with different airflows Date T amb >25oC T amb >28oC RH amb. TH duration Ref.H duration Condsate of en 49 06 82 09 at he RH ed 16 hours oC hours oC % hours hours Liters Cromer 08/06/02 11:55 30.18 5:1530.9467.939:16:218:45:40 28. Trial test 08/24/02 12:35 28.05 7:1529.3471.438:18:198:13:21 27. Cromer 08/01/02 7:35 27.58 4:3030.4275.978:33:388:57:59 28. Trial test 08/26/02 7:15 27.49 3:1028.8073.957:05:205:09:40 24. The data, although quite limited to draw any general conclusions, confirmed ththe reduction in sensible cooling capacity and in the energy efficiency, observed in theprevious tests, was indeed mostly due to the reduced airflow. As it can be seen from ttrial test, with the increased airflow the Cromer cycle still was able to maintain lower levels. It maintained higher LHRs that imply greater latent fraction and better dehumidification. The increase in the airflow rate through the system, though, improvboth the total cooling and the energy efficiency. The psychrometric charts (Figures 4-and 4-17) show that the states of the air in the Cromer cycle are very similar regardless of

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55 the air flow rate. Since, however, the sensible cooling performed by the coil increases with the increased air flow, it is expected that the unit will on for shorter periods to satisfy the thermostat. This is expected to result in lower overall energy consumption. The shorter run periods, however, will make the indoor RH fluctuate more compared to the case with the lower flow rate.

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56Figure 4-14. Indoor temperature and RH profiles for Cromer cycle with different flow rates. (A) Cromer set-No.3/02. test-10/12/02. (C) Cromer set-No.3-08/19/02. (D) Trial test-10/13/02. -093/0(B) Trial 72 1913 20304050607013579111315119213Time of dayT [oC] & RH [%] 203040506070135791113157122Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%] 2030405060701357911131517192123Time of dayT [oC] & RH [%]

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57 15000200002500030000350002123252729313335T amb [oC]Q total [kJ/h] 678910112123252729313335T amb [oC]EER [Btu/h / W] 500065008000950011000125001400026283032343638RH in [%]Q lat [kJ/h] 0.20.250.30.350.40.450.526283032343638RH in [%]LH R Figure 4-15. Comparison of performance characteristics. (A) Q total vs T amb. (B) EER vs T amb. (C) LHR vs RH in. (D) Q lat.vs RH in.

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58 Figure 4-16. Psychrometric chart for similar days (Cromer set No.3, 09/03/02 Trial test, 10/12/02)

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59 Figure 4-17. Psychrometric chart for similar days (Cromer set No.3, 08/19/02 Trial test, 10/13/02)

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CHAPTER 5 CONCLUSIONS The objective of the present study was to test the performance of the Cromer cycle in field conditions. Based on what was observed in the field test conducted a few conclusions can be drawn. The field tests confirmed the feasibility of the Cromer cycle. In hot and humlocations the technology enhances the dehumidification potential of the standard ACsystem. The field test, however, did not confirm the predicted energy savings. In field conditions lower indoor RH levels were achieved with a corresponding increase in overall energy consumption. In summary, the field study of the Cromer cycle technology confirmed that under one and the same thermostat setting, an AC system retrofitted with the Cromer cyclmaintains lower indoor RH levels in the space. The retrofitted system, however, accomplishes the AC at a higher overall energy consumption. The following additional observations were made in regard to the Cromer cycle operation: Introduction of the Cromer cycle equipment increases the pressure drop in tsystem thus reducing the airflow rate. Therefore when an existing AC syste to be retrofitted with the Cromer cycle larger air handling unit has to be inst to overcome the additional pressure drop; The Cromer cycle enables a conventional AC system to maintain lower indohumidity levels; The Cromer cycle increases the latent heat ratio of the AC system; id the e he m isalledor 60

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61The Cromer cycle reduces the sensible cooling performed by the cooling coil, which results in longer run time to satisfy the thermostat setting. Therefore under one and the same thermostat setting the Cromer cycle has a higher overall energy requirement compared to the standard configuration; The air in the supply ductwork is much drier, that helps prevent fungus and bacteria from growing in the dthe building is at lower risk from health problems caused by sunpleasant odor is introduced into the space. The equipment, at least in the configuration tested in the present study, requires considerable additional space that not many homeowners can spare and may be willing to dedicate. In the tests conducted on hot days the Cromer cycle AC system maintained indoor relative humidities around 30%. For residential houses such low humidity levels though are neither required nor recommended. Therefore during days with high ambient temperatures, the thermostat for the Cromer cycle AC system could be set at a higher temperature. Because of the enhanced dehumidification abilities, even with the higher indoor temperature the Cromer cycle would be able to maintain the indoor conditions within the ASHRAE comfort zone. The higher thermostat setting, however, would result in shorter operational time and reduction in the overall energy consumption. Furthermore for applications, where maintaining low humidity levels is a must, the technology is feasible and may be considered as a possible solution. For the same thermothat theation. The Cromer cycle, however, reas provide and maintain much lower indoor RH levels than the standard configuration. uct linings, so uch contamination; For a short period (2 to 3 minutes) of operation after a longer idle period, an stat setting the AC system in Cromer cycle configuration consumes more energy conventional high-efficiency AC configur inces the moisture removal capabilities of the cooling coil and AC system is able to

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APPENDIX A DATA SETS This Appendix contains summarized information for all the data sets processed for the purposes of the Cromer cycle field study.

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63Table A-1. Summary of all the data sets processed Solar House Reference House Tamb>25oC Tamb>28 oC Tamb>32 oC RH (25) Date Duration AC Wheel Energy Cond. DurationEnergy Duration Temp Duration Temp. Durat Temp. Hours Wh Wh Wh Liters Hours Wh hours oC hours oC hours oC % BASELINE SET 17-Sep-2001 6:04:40 17730 1773021.99:55:403400 09:5028.246:1528.7453.28 18-Sep-2001 6:39:18 18660 1866020.89:10:18297908:4026.674:0028.8871.62 19-Sep-2001 9:13:40 27020 2702024.611:45:403979012:00 28.627:1029.0565.59 20-Sep-2001 9:58:34 29770 2977026.512:09:384228014:00 28.928:3030.3464.81 21-Sep-2001 11:35:59 34110 3411028.413:46:594701013:35 28.129:1030.8570.25 22-Sep-2001 9:24:59 27410 2741030.911:52:40414209:0030.688:1531.0763.39 CROMER SET No.1 3-Oct-2001 1:57:40 5340 8054208.53:52:00123808 :3027.393:2528.4644.01 4-Oct-2001 4:53:38 13470 190136609.56:44:422371 09:2028.355:5028.9350.06 5-Oct-2001 7:42:38 21080 3602144025.28:36:192853 010:1028.796:5529.8555.09 6-Oct-2001 10:46:40 29970 4303040030.310:02:433350 011:3528.286:3529.4271.10 7-Oct-2001 2:59:40 7920 140806016.93:07:1996808-Oct-2001 1:45:20 4850 7049205.63:39:591181 05:5525.9359.80 10-Oct-2001 4:18:20 11640 1601180013.25:38:001865 07:4026.281:2028.3362.93 11-Oct-2001 6:34:21 17670 30017970217:02:232341 08:5527.894:2028.6653.13 12-Oct-2001 6:57:40 18890 3201921019.86:50:202291 08:4026.060:1728.1567.29 13-Oct-2001 8:22:00 22800 3002310026.510:10:403341 010:1027.714:3529.1461.01 14-Oct-2001 8:35:02 23390 3702376028.36:19:58 206506:2526.0382.31 15-Oct-2001 3:43:40 9990 170101604:40:38151706 :2027.221:1528.2838.36 16-Oct-2001 4:17:38 11670 180118504:23:181426 07:2527.040:4027.8049.30 BASELINE SET 6-Jun-2002* 8:16:20 25620 25620 21.7 9:10:40 31800 10:25 29.03 7:25 29.68 64.45 7-Jun-2002 5:53:42 17740 17740 18.3 6:25:41 21650 10:05 26.93 3:05 30.23 76.16

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64Table A-1. Continued Solar House Reference House Tamb>25oC Tamb>28 oC Tamb>32 oC RH (25) Date Duration AC Wheel Energy Cond. DurationEnergy Duration Temp Duration Temp. Durat Temp. Hours Wh Wh Wh Liters Hours Wh hours oC hours oC hours oC % 8-Jun-2002 3:40:40 11060 11060 14.0 4:13:40 14190 7:05 26.79 1:40 28.29 74.51 9-Jun-2002 4:57:18 15110 15110 19.5 6:34:40 22450 11:40 27.39 5:15 28.30 66.86 10-Jun-2002 5:25:20 16600 16600 20.7 8:06:20 27480 12:30 27.82 6:15 28.52 66.05 11-Jun-2002* 3:46:58 11450 11450 13.9 4:36:01 15480 5:50 26.87 0:50 28.50 75.62 12-Jun-2002 7:07:39 22060 22060 24.9 8:52:00 30590 12:55 28.47 7:00 29.62 0:55 32.52 70.31 13-Jun-2002 8:25:40 26400 26400 26.2 11:46:00 41550 10:50 30.68 9:40 30.94 2:55 33.15 61.91 14-Jun-2002 10:02:20 31820 31820 30.5 12:36:00 44250 15:45 29.94 11:15 31.37 4:25 32.85 63.9 15-Jun-2002 9:52:00 30950 30950 25.6 11:48:20 41010 15:00 27.54 11:05 31.17 3:55 32.70 68.53 16-Jun-2002 8:00:40 24870 24870 20.7 9:29:40 33190 13:45 29.29 10:55 29.94 52.03 17-Jun-2002 2:23:40 7050 7050 9.4 2:50:00 9320 1:10 25.18 76.45 18-Jun-2002 rainy and cold 0:36:40 1970 19-Jun-2002* 0:44:00 2250 2250 2.5 2:55 26.94 0:40 28.53 74.31 CROMER SET No.2 19-Jun-2002* 4:20:20 12720 1901291017.73:18:3911470 3: 1528.51 2:50 29.29 59.90 20-Jun-2002 5:20:41 15620 2301585023.85:35:22188409:2026.962:1529.0470.18 21-Jun-2002 2:14:40 6400 100650011.32:40:1987300:202574.50 22-Jun-2002 0:41:00 1960 3019903.923-Jun-2002 4:02:00 11910 1601207019.74:57:59168409:0526.172:3028.6480.79 24-Jun-2002 6:07:21 17920 2701819025.25:53:39200909:0528.086:4528.6267.89 25-Jun-2002 3:46:00 10850 1701102016.85:00:19175505:0527.82:2028.8971.81 26-Jun-2002 7:40:59 22370 3202269030.06:43:0023380 10:3027.433:5528.6772.30 27-Jun-2002 7:23:38 21560 3202188027.26:56:2124270 11:0527.886:0029.0671.11 28-Jun-2002 10:14:40 30080 4503053034.58:48:403094011: 4029.638:3530.471:5032.3074.52 29-Jun-2002 7:36:38 21980 3202230027.06:28:22221806:2029.334:4030.2880.04 30-Jun-2002 5:06:20 14800 2201502020.74:58:00170006:4527.142:3529.2687.45

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65Table A-1. Continued Solar House Reference House Tamb>25oC Tamb>28 oC Tamb>32 oC RH (25) Date Duration AC Wheel Energy Cond. DurationEnergy Duration Temp Duration Temp. Durat Temp. Hours Wh Wh Wh Liters hours oC hours oC hours oC % 1-Jul-2002 7:06:22 20930 2802121029.68:57:0131200 11:1528.076:1029.278.86 2-Jul-2002 10:05:20 29450 4602991035.17:53:2027430 10:4529.028:3529.7675.83 3-Jul-2002 8:05:20 23500 3902389028.47:00:40246206:5 529.775:3030.630:15 32.1777.14 4-Jul-2002 7:00:20 20370 3002067025.36:03:40215509:0527.593:4029.6783.01 BASELINE SET 1-Aug-2002 7:05:15 21280 21280 22.9 8:20:20 28880 12:30 27.06 5:00 30.13 76.8 2-Aug-2002 5:54:00 17780 1778018.28:05:40274607:3027.144:4529.7475.81 3-Aug-2002 5:48:00 17360 1736017.57:34:00257007:1028.24:4029.1569.65 4-Aug-2002 4:37:20 13710 1371017.75:17:20197704:5527.522:1528.6678.81 5-Aug-2002 8:51:53 27400 27400 27.0 10:42:20 37350 15:10 29.02 9:45 30.48 0:30 32.31 70.74 6-Aug-2002 11:21:18 35850 35850 32.2 13:58:21 49310 16:00 27.96 12:30 31.99 7:00 33.54 75.31 7-Aug-2002 8:43:23 26470 2647029.99:40:003280020:5026.84:4528.6179.72 8-Aug-2002 4:28:42 13540 1354014.17:16:382466010:50 28.487:5029.1847.54 9-Aug-2002 4:12:01 12460 1246015.06:36:01220606:4526.593:5028.5465.44 10-Aug-2002 6:32:00 19960 1996021.89:20:203207012:0528.97:5529.4459.13 CROMER SET No.3 12-Aug-2002 4:51:57 13930 210 14140 19.6 4:07:59 13690 3:25 26.98 1:00 28.8 77.29 13-Aug-2002 7:27:42 22220 3202254028.96:40:012324 08:3528.125:2029.2668.87 14-Aug-2002 8:39:43 26670 3902706030.09:11:003222 010:0027.647:2030.3976.80 15-Aug-2002 6:15:00 18810 2901910022.26:24:002237 05:3529.034:3029.772.06 16-Aug-2002 10:42:59 33260 4803374035.212:11:4043290 15:5028.529:0529.751:2432.2973.30 17-Aug-2002 11:24:20 35190 5103570040.512:02:2042950 11:4527.548:0530.942:5032.7978.82 18-Aug-2002 9:33:40 29130 4202955032.79:17:40327307 :5029.756:0530.720:3532.4266.80 19-Aug-2002 8:33:38 25180 3802556028.88:57:59314007 :3527.584:3030.420:4032.1575.97

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66 Table A-1. Continued Solar House Reference House Tamb>25oC Tamb>28 oC Tamb>32 oC RH (25) Date Duration AC Wheel Energy Cond. DurationEnergy Duration Temp Duration Temp. Durat Temp. Hours Wh Wh Wh Liters Hours Wh hours oC hours oC hours oC % 20-Aug-2002 6:02:36 17280 2601754021.34:37:401544 03:4027.641:05 28.9676.33 21-Aug-2002 9:25:20 27920 4202834029.510:56:573848 014:1029.029:10 30.4166.71 22-Aug-2002 10:19:18 30540 460 31000 30.7 11:25:59 40000 14:20 29.19 9:10 30.98 2:25 32.49 64.14 23-Aug-2002 11:42:39 34740 5003524033.110:45:0037850 15:5029.4310:50 30.911:5032.3762.03 24-Aug-2002 12:56:18 38640 570 39210 38.7 13:58:39 49840 16:15 27.68 12:25 31.4 6:25 32.91 70.90 25-Aug-2002 14:32:01 43260 6504391042.013:10:2146380 18:1527.619:55 30.425:0533.0474.56 26-Aug-2002 11:49:19 34540 530 35070 37.2 10:27:21 36170 12:15 26.54 5:15 29.94 79.34 27-Aug-2002 6:38:22 19280 2901957025.36:11:012136 06:5527.171:30 28.1278.27 28-Aug-2002 8:24:39 24440 4002484027.710:09:233505 09:2027.965:50 28.8673.60 29-Aug-2002 6:37:59 19210 3101952022.67:32:012534 08:0528.085:10 28.9271.55 30-Aug-2002 4:35:21 13120 2101333016.74:12:381410 04:4527.251:30 29.0678.49 31-Aug-2002 6:03:42 17670 2701794022.06:02:192046 010:1026.90:40 28.1978.02 1-Sep-2002 8:56:18 26390 4202681029.68:51:403118 013:0528.435:50 30.4173.56 2-Sep-2002 10:07:22 29720 4303015031.49:32:593322 015:0028.317:35 29.9971.51 3-Sep-2002 9:16:21 27090 4202751028.58:45:403030 011:5530.185:15 30.9467.93 TRIAL TEST 11-Oct-2002* 8:48:18 27040 3802742032.28:32:002909 010:2029.237:30 30.2562.71 12-Oct-2002 8:18:19 25010 3802539027.18:13:212874 012:3528.057:15 29.3471.43 13-Oct-2002 7:05:20 21290 3002159024.15:09:401826 07:1527.493:10 28.873.95 14-Oct-2002 5:15:22 15840 2301607019.75:43:202053 06:5528.114:30 29.0667.52

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AP PE ND IX B UNCERTAINTY ANALYSpendix presents the uncertainty analysis carried out to evaluate the unc thcalculated usiasured vices used to measure the relative humidity, temperature, air velocity, etc. have ceraonentally meal measurements. Table B-1. Uncertainty of experimental measurements IS Th is ap ertang th inty of th e e xpe rim en tal me as ure me nts as we ll a s of e q ua ntit ies ese mDe e vari ables. tain acc ur cy tha t im pa cts th e u nce rta int y o f th e c orr esp din g e xpe rim asur ed q ua nti ties T abl e B -1 pre se nts the un ce rtai nty of the experim ent Q ua ntit y I nst rum en t Unc lati ve h um id ity HM D 60U /Y O 2 mp erat HM D6 U/Y ity Ho ire A nem o met er 3 mfe ren Th e un ce rta inty an aly sis of th e c alc ula ted va lue s, th use ex pe rim asur ed q nti ties w as do ne foll ow ing th e m eth od d escr ed by Col em ethN n od um invbe olvr of es m theeas foure llowd v inar g piab roles ced X ure: : L et c ert ain ex per ime ion of XR n X.., X3 X,1 ,... ,2 2nX 2U 2XU 2 2XR 21 2XU ... 2 n XR R (B-2) ertainty Re% Teure 0O 0.3 oC Air veloc% reading t W Circuce Ruler 0.5 cm Watt-hours Transducer Model WL40R-052 0.5% F.S. atentally meuaiban [1999]. Briefly the mntal result R, is a funct(B-1) Then the uncertainty in the result is given by i R 2RU 1X 67

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68where the iXU are the uncertainties in the measured variables. By dividing each term in the equation by iX 2 R and by multiplying each term on the right-hand side by iiXX we obtain the uncertainty equation in a nondimensionalised form: 22222221212nnXXRXXRXXRR 21....21XnXXRURXURXURXUn (B-3 ) where RU XU R iXiuncertainties for each variable. The factors in the parenthesis that multiply the relative uncertainties ovariables are call is the relative uncertainty of the result. The factors are the relative f the ed uncertainty magnification factors (UMFs). They indicate the influence of the uncertainty of the corresponding variable on the uncertainty in the result. If a UMF is greater than 1 this indicates the varified as it propagates through the data reduction equation into the result. If UMF value is less tcertainty iriable is diminished as it propagates through the data duction equation into the result. in the Latent cooling that the uncertainty in iable is magn han 1 then the un n the va re For instance, this method applied to our study to determine the uncertainty 2'1lathlathlatQUQUQUQUlat (B-4) '41hhmQlat gives the following: 224214'mmhh The palat ariables, used for its calculation: rtial derivatives of Qin respect to the three v mhQlat1 ; mhQlat'4 and '41hhmQ (B-5) lat

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69 By substitug in the equation and nondimensionalising we obin tinta 21'mhhhhhhQUQlat 242414224112''4''1UUhUhmhhlat (B-6) All the calculated quantities, the functions of those quantities, the partial derivatives of these functions with respect to the variables they depend on and the corresponding non-dimensional form of the uncertainty equation, are listed in taIn thedetermined by picking several days in each set of data, averaging the daily values for each day, finding the corresponding uncertainty and after that finding the average uncertainty for each data set. This process is illustrated in table B-2. The higher uncertainties observed in respect to Q lat and LHR are as a result of the comparatively small moisture removal. As it can be seen from the corresponding uncertainty equations, this small moisture removal makes the denominator (h1-h4') small and consequently the UMFs are high. Therefore in theses cases the uncertainties of the measured quantities magnifies as they propagate through the data reduction equations into the final results for Q lat and LHR. ble B-4. current study uncertainties of the quantities calculated have been

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70 Table B-2. Average uncertainty Date U latent U sens U LHR U total U EER U h1 U h4 U h4' % % % % % % % % N o wheel 6 June, 200231.16 7.49 29.26 6.23 6.25 2.30 2.17 2.74 8.73 June, 200225.91 10.68 22.32 7.88 7.90 2.20 2.07 2 12 June, 200226.23 8.44 24.17 6.58 6.60 2.25 2.09 2.6 16 June, 200233.07 9.84 28.58 8.09 8.11 2.32 2.13 2.73 9 June, 200224.76 11.38 21.14 8.10 8.11 2.17 2.05 2.68 6 14 June, 200229.35 8.05 27.42 6.47 6.48 2.27 2.11 2.80 AVERAGE 28.41 9.31 25.48 7.23 7.24 2.25 2.10 2.72 Wheel (42 rpm) 28 June, 200223.89 11.28 20.97 7.68 7.70 2.57 2.67 4.60 AVERAGE 22.51 11.37 21.25 7.57 7.59 2.56 2.64 4.4 13 Aug., 200219.23 8.28 16.93 6.13 6.15 2.23 27 June, 200221.12 11.63 18.24 7.59 7.60 2.56 2.60 4.21 3 July, 200222.52 11.19 24.55 7.45 7.46 2.56 2.66 4.67 9 Wheel (11 rpm) 2.55 3.86 28 Aug., 200224.22 8.30 21.36 6.59 6.61 2.54 2.67 3.81 30 Aug., 200222.16 8.70 19.64 6.53 6.55 2.45 2.60 4.23 1 Sep., 200224.76 8.39 22.01 6.62 6.64 2.53 2.64 4.02 3 Sep., 200223.89 7.26 21.98 5.83 5.85 2.03 2.69 3.92 Table B3. Uncertainty of calculated values 31 Aug., 200220.53 8.73 17.79 6.53 6.55 2.44 2.58 3.76 2 Sep., 200225.46 8.27 22.51 6.66 6.68 2.57 2.69 3.74 AVERAGE 22.89 8.28 20.32 6.41 6.43 2.40 2.63 3.91 Quantity No wheel Wheel (42 rpm) Wheel (11 rpm) 1. Enthalpy Point 1: 2.25 % Point 4: 2.10 % Point 4': 2.72 % Point 1: 2.56 % Point 4: 2.64 % Point 4': 4.49 % Point 1: 2.40 % Point 4: 2.63 % Point 4': 3.91 % 2. Mass flow rate 3.1 % 3.1 % 3.1 % 3. Sensible cooling 9.31 % 11.37 % 8.28 % 4. Latent cooling 28.4 % 22.51 % 22.89 % 5. Total cooling 7.23 % 7.57 % 6.41 % 6. LHR 25.48 % 21.25 % 20.32 % 7. EER 7.2 % 7.59 % 6.43 %

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71Table B4. Calculated values Qtuo Plderives uan ity F ncti n artia '4h 1h lat lat 4' 1h mQlat ble sens 4 .m sens .m 4'hQsens 4h Q 4'h mQsens ling 4 .m total .m 1hQtotal 4h Q 1h mQtotal ativ '4h ; U nce rta int ye tio qua n 2' 2 4'h 2 2 1hh 2 4hUh mm U QU h h Qlat 2 44hh 2 44h 4' 2 4h 4h 4h 4'' ''4 h U Q mm sensQsens 2 2 2 1h 2 4Uh 1Uh m U U h Qtotal Latent cooling Qlat .mQ .1mhQ .mhQlat ; 2441141''1'hhUhlat 4'hhQ .msens 4h 222UUhhUh 1hhQ .mtotal 4h 244141241mhhhhhhQtotal ; Sensi cooling Q Total coo Qtotal ;

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Table B. Continued 72Latent heat ratio Rlat 1hRlat 44'hhh 244'hhhhhRlat 4'hlat 144'hhhhRlat 24241424241421244124''4''1'hUhhhhUhhhhUhhhRUhhhlatRlat 4144'hhhhRsens 241441'hhhhhRsens 4141'hRsens 24114hhhhRsens 212411242444242414414421''4''4''hUhhhhUhhhhUhhhhhhhRUhhhsensRsens intotalWQEER intotalWQEER1 2WWEER 222inWtotalQEERWUQUEERUintotal 1 411 41hh 1R 241h 4141'hhhh hh 4'h EER intotalQ Sensible heat ratio Rsens Energy efficiency ratio

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APPENDIX C FORTRAN 77 PROGRAM FOR CALCULATION OF PERFORMANCE CHARACTERISTICS OF THE COOLING CYCLE The following program was written to calculate the parameters used to evaluate the performance of the cooling cycle. These parameters are Qtotal, Qlat, Qsens, LHR, SHR and apparent energy efficiency ratio. The program also obtains such thermophysical properties of the moist air as enthalpy and humidity ratio. To accomplish the latter the program uses a link to the software package PROPATH (PROgram PAckage for THermophysical properties of fluids). PROGRAM CROMER.FOR C ***************************************************************** C THIS PROGRAM CALCULATES THE FOLLOWING PERFORMANCE C CHARACTERISTICS C LAT AND SENSIBLE COOLING C LATENT HEAT RATIO AND SENSIBLE HEAT RO C *TOTAL COOLING PERFORMED BY AN AC HANDLER C *APPARENT ENERGY EFFICIENCY RATIO C AND BASED ON TEMPERATURE AND RELATIVE HUMIDITIES C *FINDS ENTHALPY AND ABSOLUTE HUMIDITY C **************************************************************** C C C DECLARATIONS OF TABLE COLUMNS REAL TEMPO(25), ENTH(25,10),HUMR(25,10),TIME(25),HDIF(25) DECLARATION OF THE MAIN ARRAYS REAL INPUT (25,13),RESULT (25,9),PROPERTY(25,11), POWER (25) INTEGER AIRFLOW IROW NUMBER OF ROWS I3 NUMBER OF COLUMNS (12 AC WITH NO WHEEL) CHARACTER*10 FILESOURCE, FILERESULT, PROPERTIES, ENTEXT, HRTEXT FORMATION REQUIR THE LINK TO THE PERTY PROGRAM MON/UNIT/ KPA, M *TEN : ATI FOR 1 IN CO ED FORESS ROP M C C C C C C C 73

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74 KPA=1 MESS=1 P=1.01325 C C DATA INPUT COMMUNICATION WITH THE USER C ENTEXT=' H' HRTEXT=' W' P READ*, FILESOURCE PRINT*, 'ENTER A NAME FOR TENSION' RE PR READ*, AIRFLOW READ*, IROW C 1 FORM='FORMATTED',RECL=120) READ(20, FMT=100) (TEMPO(I2), I2=1,10),TIME(I1),POWER(I1) 11 CONTINUE INPUT(I1,I3)=TIME(I1) 10 CONTINUE CL LIN FOR DETERMINATION OF EN D 100) PROPERTY(I1,I3)= ENTH(I1,I3)*0.001 PROPERTY(I1,I3+1) = HUMR(I1,I3)*1000 Tret = INPUT(I1,3) O(I1)*0.001 PRINT*,'H4PR=',PROPERTY(I1,11) ONTINUE COOLING CAPACITY AND EER C RINT*, 'ENTER THE NAME OF THE SOURCE FILE + EXTENSION' HE RESULT FILE +EXT AD*, FILERESULT INT*,'PLEASE ENTER THE AIR FLOW [kg/h]' PRINT*,'PLEASE ENTER NUMBER OF ROWS' C C DATA INPUT PROGRAM READS FROM THE USER'S FILE OPEN (20, file=FILESOURCE,ACCESS='DIRECT', DO 10 I1=1,IROW DO 11 I3=1,10 INPUT(I1,I3)=TEMPO(I3) INPUT(I1,I3+1)=POWER(I1) 100 FORMAT (1X, 10(F6.2), F6.4, 1X,F7.1) OSE(20) C C K TO PROPATH PROPERTY PROGRAM C THALPY AND ABSOLUTE HUMIDITY C O 13 I1=1,IROW DO 14 I3=1,9,2 ENTH(I1,I3)=HC(P,INPUT(I1,I3),(INPUT(I1,(I3+1)))/ HUMR(I1,I3)=XC(P,INPUT(I1,I3),(INPUT(I1,(I3+1)))/100) 14 CONTINUE 13 CONTINUE C C CALCULATION OF POINT H4prime=f(Wsup,Tret) C C Wsup = PROPERTY(I1,10), DO 15 I1=1,IROW TEMPO(I1)=HD(P,INPUT(I1,3),(PROPERTY(I1,10)*0.001)) PROPERTY(I1,11)=TEMP 15 C C C C CALCULATION OF SHR, LHR

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75 C CALCULA TION OF SENSIBLE HEAT RATIO (SHR) LATENT HEAT RATIO (LHR) DO 17 I1=1,IROW RESULT(I1,1)=(PROPERTY(I1,11)-PROPERTY(I1,9))/HDIF(I1) )=(PROPERTY(I1,3)-PROPERTY(I1,11))/HDIF(I1) TAL COOLING CAPACITY FLOW =RESULT(I1,4)*0.94782 PRINT*,'COOLING=', RESULT(I1,4) CR INPUT) ESULT(I1,5)*INPUT(I1,11)/RESULT(I1,6) IBLE AND LATENT COOLING W PERTY(I1,9))*RESULT(I1,3) ,9)=(PROPERTY(I1,3)-PROPERTY(I1,11))*RESULT(I1,3) CONTINUE RESULT) 07) et','Tbef','RHbef', 106) 'oC ',' % ',' oC ',' % ',' oC ',' % ', C ',' % ',' hours' DO 20 I1=1, IROW UT(I1,11) CONTINUE ntext,'Pr' W x, A2,a3) ,1X,5(F8.3, F8.3),1X,F8.3) WRITE(21, FMT=107) WRITE(21, FMT=104) 'SHR','LHR','FLOW','COOLING','COOLING', WRITE(21, FMT=104) ',' ','kg/h',' kJ/h ',' Btu/h', C AND C HDIF(I1)=PROPERTY(I1,3)-PROPERTY(I1,9) RESULT(I1,2 17 CONTINUE C C CALCULATION OF TO C Q total = (h1-h4) x (mass flow rate) C DO 18 I1= 1,IROW RESULT(I1,3)=AIR RESULT(I1,4)=HDIF(I1)*AIRFLOW RESULT(I1,5) 18 CONTINUE C CALCULATION OF EER = (TOTAL COOLING)/(POWE C DO 19 I1=1, IROW RESULT(I1,6)=INPUT(I1,12) RESULT(I1,7)=R 19 CONTINUE C C CALCULATION OF SENS C DO 22 I1= 1,IRO RESULT(I1,8)=(PROPERTY(I1,11)-PRO RESULT(I1 22 C C RESULTS RECORDED IN A FILE C OPEN (21, file=FILE WRITE(21, FMT=1 WRITE(21, FMT=108) 'DATE IS:', FILESOURCE WRITE(21, FMT=107) WRITE(21, FMT=106) 'Tth','RHth','Tret','RHr 1 'Taft','RHaft','Tsup','RHsup',' Time' WRITE(21, FMT= 1 oC ',' % ',' o WRITE(21, FMT=103) I1,(INPUT(I1,I3), I3=1,10),INP 20 WRITE(21,101) (ENTEXT,I1,HRTEXT,I1, I1=1,5), E DO 16 I1=1,IRO WRITE(21, FMT=102),I1, (PROPERTY(I1,I3), I3=1,11) 16 CONTINUE 101 FORMAT (/5(5X, A2, I1, 5X, A2,I1),6 102 FORMAT (I2 1 'POWER','EER','SENS COOL','LAT COOL'

PAGE 87

76 1 Wh ',' ','kJ/h','kJ/h' DO 21 I1=1,IROW WRITE(21, FMT=105) I1,(RESULT(I1,I3),I3=1,9) A4, 2X,A4, 1X,A6, 2(2X,A8), 4X,A5, 2X,A4, 1 3X,A9, 3X,A9) .0, FORMAT (5X,A5, 4X,A5, 3X,A5, 2X,A6, 2X,A5, 2X,A7, 4(1X,A7), 21 CONTINUE C C 103 FORMAT (1X, I2, 10(F8.2), 1X,F8.4) 104 FORMAT (5X, 105 FORMAT (I2,1X,2(1X,F5.2), 2X,F6.0, 2(F10.2), 2X,F6 1 2X,F5.2, 1X,F10.2, 2X,F10.2) 106 1 3X,A6) 107 FORMAT (//) 108 FORMAT (2(2X,A10)) CLOSE(21) END

PAGE 88

A PPENDIX D ES LATENT COOLING TRENDLIN

PAGE 89

78 Figure D-1. Latent cooling vs. RH in. (A) Baseline 06/07/02, 06/09/02; Cromer 06/26/02, 06/27/02. (B) Baseline 06/10/02, 06/13/02; Cromer 06/26/02, 06/27/02. (C) Baseline 08/01/02, 08/06/02; Cromer 08/24/02, 08/26/02. (D) Baseline 08/02/02, 08/05/02; Cromer 08/16/02, 08/19/02. (E) Baseline 08/03/02, 08/06/02; Cromer 08/19/02, 08/24/02. (F) Cromer set No.3-08/19/02, 09/03/02; Trial test-10/12/02, 10/13/02. Cromer cycley = 284.59x + 649.4R2 = 0.9693Standard configurationy = 474.01x 11711R2 = 0.9051650080009500110001250014000283134374043464952RH in [%]Q lat [kJ/h]. Cromer cycley = 273.6x + 2770.5R2 = 0.7958Standard coationy = 585.47076R2 = 0.6500800095001100012500140002629323538414450RH in [%]Q lat [kJ/h] nfigx 8947 ur1716

PAGE 90

79 Figure D-1. Continued Cromer configurationy = 348.61x 2615.7R2 = 0.6453Standard configurationy = 403.52x 9804.5R2 = 0.71445000600070008000900010000253035404550RH in [%]Q lat [kJ/h] Cromer configurationy = 333.23x 2238R2 = 0.942Standard configurationy = 466.38x 12367R2 = 0.7493600070008000900010000110002831343740434649RH in [%]Q lat [kJ/h]

PAGE 91

80 Trial testy = 335.63x 358.81R2 = 0.4256Cromer test No.3y = 358.45x 3025R2 = 0.9234500065008000950011000125002426283032343638RH in [%]Q lat [kJ/h] Cromer cycley = 326.13x 2114.9R2 = 0.8813Standard configurationy = 505.12x 14006R2 = 0.69485500650075008500950010500252831343740434649RH in [%]Q lat [kJ/h] Figure D-1. Continued

PAGE 92

LIST OF REFERENCES American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE). (1996). ASHRAE Handbook of HVAC Systems and Design, Atlanta, Georgia. American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc. (ASHRAE). (1997). ASHRAE Handbook of Fundamentals, Atlanta, Georgia. Chant E. and Jeter S. (1994). A Steady-state simulation of an advanced desiccant-enhanced cooling and dehumidification system. ASHRAE Transactions, v.100, pt.2, 339-347. Coleman H. and Glenn S. (1999). Experimentation and Uncertainty Analysis for Engineers, 2nd edition, Wiley Inter-science, New York. Cromer C. (1988). United States patent, Patent Number 4719761, Date of Patent, January 19, 1988. Cromer C. (1997). Cromer cycle: An energy efficient solution to indoor air quality problems. Engineering Solutions to Indoor Air Quality Problems, July 1997, Research Triangle Park, NC. Dolan W. (1989). Desiccant cooling systems a new HVAC opportunity. Energy Engineering, v.86, n.4, 6-9. Energy Information Administration (EIA). 2000. Available from URL: http://www.eia.doe.gov/emeu/consumptionbriefs/recs/actrends/recs_ac_trends.html. Site last visited September 2002 Jones W. (2001). Air Conditioning Engineering. 5th edition, Oxford Press, Boston. Hands Down Software Group, ASHRAE Psychrometric Chart, ASHRAE, 1992. Kosar D., Witte M., Shirey D. and Hedrick R. (1998). Dehumidification issues of standard 62-1989, AHRAE Journal, 71-75. Lizardos E. (1993). Designing HVAC systems for optimum indoor air quality. EnergEngineering Journal of the Association of Energy, v.90, n.4, 6-29. Mago P. and Goswami Y. (2001). A study of the performance of a hybrid liquid desiccant cooling system using lithium chloride. Proceedings of the International SolEnergy Conference, ASME, April 2001, 133-139. y ar 81

PAGE 93

82Nimmo B., Collier R. and Rengarajan K. (1993). DEAC: Desiccant enhancement of cooling-based dehumidification. ASHRAE Transactions: Symposia of the 1993 ASHRAE Winter Meeting, v.99, pt.1, 842-848. Oberg V. (1998). Heat and Mass Transfer Study of a Packed Bed Absorber/Regenerator for Solar Desiccant Cooling. Drsity of Florida, Gainesville. t -254-4147. ). An is ations, AES, v.29, 129-138. al Engineering, v.22, n.12, 1347-1367. k W. (1993). Numerical simulation of combined heat and mass transfer processes in a rotary dehumidifier. Numerical Heat Transfer: An Int. Journal of and Novosel D. (1995a). Effect of operating conditions on optimal performance of rotary dehumidifiers. Journal of Energy Resources Technology, Zheng W., Worek W. and Novosel D. (1995b). Performance optimization of rotary ASME, v. 117, octoral Dissertation, Unive Pesaran A., Penney T. and Czanderna A. (1992). Desiccant cooling: state-of-the-arassessment. National Renewable Laboratory, Golden, Colorado, NREL Report No. NREL/TP PROPATH Group. (2001). PROPATH: A Program Package for Thermophysical Properties of Fluids, version 12.1. Rengarajan K. and Nimmo B. (1993). Desiccant enhanced air conditioning (DAECapproach to improved comfort. Heat Pump and refrigeration Systems Design, Analysand Applic Zhang L. and Niu J. (2002). Performance comparisons of desiccant wheels for airdehumidification and enthalpy recovery. Applied Therm Zheng W.and Wore Computation and Methodology, part A, v.23, n.2, 211-232. Zheng W., Worek W Transactions of ASME, v. 117, n.1, 62-66. dehumidifiers. Journal of Solar Energy Engineering, Transactions of the n.1, 40-44.

PAGE 94

BIOGRAPHICAL SKETCH spired by her father. He was not only one of the best experts in ed Bronislava to find her way in engineering. Bronislava began her engineering studies at engineering. After spending a few years working for an engineering company in Sofia, was versity of Florida, Bronislava was oni) and support were priceless for her. Bronislava Veltcheva was born in Sofia, Bulgaria. To pursue a career in Engineering she was in the thermal science field in Bulgaria. His love, devotion and enthusiasm encourag the Technical University of Sofia, where she obtained her B.S. degree in mechanical she was invited by her cousin Ani to visit Gainesville, Florida. During her stay there simply from curiosity, Bronislava started going to classes. Very soon, however, she thrilled by the excellent research opportunities at the University of Florida. A year later Bronislava returned to Florida (this time as a graduate student in the College of Engineering). During her studies at the Uni accompanied by her husband Ivan and her two wonderful little daughters (Valli and Twhose love 83


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FIELD STUDY OF THE ROTARY DESICCANT SYSTEM
USING THE CROMER CYCLE












By

BRONISLAVA VELTCHEVA


A THESIS PRESENTED TO THE GRADUATE SCHOOL
OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT
OF THE REQUIREMENTS FOR THE DEGREE OF
MASTER OF SCIENCE

UNIVERSITY OF FLORIDA


2003














ACKNOWLEDGMENTS

First of all I would like to express my deep appreciation to Dr. Yogi Goswami,

my advisor and committee chairman, for his guidance, tremendous support and

understanding over the last 2 years. I wish to thank my other committee members, Dr.

S. A. Sherif and Dr. D. W Hahn, for their expert advice and guidance.

Special thanks go to Dr. H. A. (Skip) Ingley for his constructive recommendations

and helpful suggestions during my research. I would like also to thank Dr. Charlie

Cromer for the discussions on his technology. Sincere thanks go to Mr. Charles

Garretson for his patience and valuable support in constructing the experimental setup.

Very sincere thanks go to my husband, Ivan, without whose motivation, belief in

my abilities and abundant love and support this degree would never have been possible.

Last, but not least, I wish to express my deep gratitude to my great cousin Ani and her

husband Nathan for their measureless support and constant positivism. They made this

experience more enjoyable and rewarding.















TABLE OF CONTENTS


A C K N O W L E D G M E N T S .................................................................................................. ii

L IST O F T A B L E S .. ............ ................................................... ............... v...... .... ..v

LIST OF FIGURES ....................................... ........... ............................ vi

LIST OF A BBREV IA TION S ................................................................ .............. viii

A B S T R A C T ........................................................................................................ ........ .. x

CHAPTER

1 IN T R O D U C T IO N ................................................................. .... ... ..... ............... 1

1.1 W hy A ir C conditioning .......................................... ........................ ...............2...
1.2 D esiccant C ooling C oncept............................................................. ...............3...

2 CROMER CYCLE ........................ ........... ...............................5

2.1 Parameters That Impact Cromer Cycle Performance....................................8...
2.2 Literature R eview ................................................................ 11
2.3 O objectives of the Present Study.................................................... ............... 12

3 EX PER IM EN TA L SE TU P ........................................ ....................... ................ 14

3.1 Experim ental Facility ................. ........................................................... 14
3.2 M easuring Instrum entation........................................................... ............... 15
3.2 D esiccant W heel ...................... ............ ... ........................... 18
3.3 Condensate M easuring Equipm ent..................................................... 24
3.4 D ata A acquisition System ...................................... ..................... ................ 24

4 PROTOCOL AND EXPERIMENTAL RESULTS .............................................27

4 .1 P ro to c o l ............................................................................................................. 2 7
4 .2 E xperim ental R esults......................................... ........................ ................ 29
4 .3 D iscu ssio n ......................................................................................................... 4 9

5 CONCLUSIONS ....................... .. ........... ......................................60












APPENDIX

A D A T A S E T S ............................................................................................................. 6 2

B U N CER TA IN TY AN ALY SIS ............................................................. ................ 67

C FO R TR A N 77 PR O G R AM ....................................... ....................... ................ 73

D LATENT COOLING TRENDLINES..................................................................77

L IST O F R E FE R E N C E S ................................................. ............................................ 81

BIO GR APH ICAL SK ETCH .................................................................... ................ 83






































iv














LIST OF TABLES


Table page

1-1 Use of air-conditioning equipment in the USA households ................................... 2

2-1 Performance comparison of a standard air handler to the same equipped
w ith the Crom er cycle equipm ent ................................................... ................ 12

4-1 Ambient conditions and run times for the data pairs from the baseline set
and Crom er set N o. 1 ...... ..... ................ ........................... 33

4-2 Ambient conditions and run times for the data pairs from the baseline set
and C rom er set N o.2 .... ............................................................... ............... 42

4-3 Ambient conditions and run times for the data pairs from the baseline set
and C rom er set N o .3 .. ................................................................. ............... 4 8

4-4 Ambient conditions and run times for two similar days for Cromer cycle
configuration but with different airflow s ........................................ ................ 54

A -i Sum m ary of all the data sets processed ............................................... ................ 63

B-i Uncertainty of experimental m easurem ents ........................................ ................ 67

B -2 A average uncertainty .. ........................................................................ ................ 70

B -3 U uncertainty of calculated values.......................................................... ................ 70

B-4 Calculated values ......................... ............ .............................71














LIST OF FIGURES
Figure page

3 1 T e st h o u se ................................................................................................................... 1 4

3-2. Location of the combined temperature and RH sensors.......................................16

3-3. R reference hou se............... .. .................. .................. ................. ..... .... .... .......... 17

3-4. L am inmates design ............. .. .................. .................. ....................... ............... 19

3-5. The experim ental w heel assem bly.................. .................................................. 20

3-6. T he experim ental setup ...................................................................... ................ 2 1

3-7. The pulley and the driving belt............................................................. ................ 22

3-8. Mechanism for monitoring number of desiccant wheel revolutions......................23

3-9. D esiccant w heel pow er supply layout................................................. ................ 23

3-10. Condensate m easuring equipm ent..................................................... ................ 24

3-11. Condensate m easuring vessel and valve............................................. ................ 25

3-12. Layout of the data acquisition system ................................................ ................ 26

4-1. Indoor temperature and RH profiles from Baseline set. .......... .................30

4-2. Indoor temperature and RH profiles for Baseline set and Cromer set No.1. ..........36

4-3. Comparison of performance characteristics. ........................................................37

4-4. Psychrom etric chart for sim ilar days.................................................... ................ 38

4-5. Psychrom etric chart for sim ilar days.................................................... ................ 39

4- 6. Indoor temperature and RH profiles for Baseline set and Cromer set No.2 ..........44

4-7. Comparison of performance characteristics. ........................................................45

4-8. Psychrom etric chart for sim ilar days.................................................... ................ 46

4-9. Psychrom etric chart for sim ilar days.................................................... ................ 47









4-10. Indoor temperature and RH profiles for Baseline set and Cromer set No.3. .........50

4-11. Comparison of performance characteristics .....................................................51

4-12. Psychrom etric chart for sim ilar days.................................................. ................ 52

4-13. Psychrom etric chart for sim ilar days.................................................. ................ 53

4-14. Indoor temperature and RH profiles for Cromer cycle with different flow rates. .56

4-15. Comparison of performance characteristics. .. ...................................................57

4-16. Psychrom etric chart for sim ilar days.................................................. ................ 58

4-17. Psychrom etric chart for sim ilar days.................................................. ................ 59

D -1. L atent cooling v s. R H in ......................................... ......................... ................ 78













LIST OF ABBREVIATIONS


AC Air conditioning

amb. Ambient

ASHRAE American Society of Heating, Refrigerating and Air-Conditioning
Engineers

ARI American Refrigeration Institute

Cond. Condensate

EER Energy efficiency ratio (ratio of cooling in Btu/h to the power
input in W)

h Enthalpy [kJ/kg]

in Inside

lat Latent

LHR Latent heat ratio
m Mass flow rate of air [kg/h]

NTU Number of transfer units


Q Cooling [kJ/h]

rph Revolutions per hour

Ref.H Reference house

RH Relative humidity [%]

SEECL Solar Energy and Energy Conversion Laboratory

sens Sensible

SHR Sensible heat ratio









T Temperature [C]

TH Test house

UMF Uncertainty magnifying function

U Uncertainty



Subscripts


lat Latent

sens Sensible















Abstract of Thesis Presented to the Graduate School
of the University of Florida in Partial Fulfillment of the
Requirements for the Degree of Master of Science

FIELD STUDY OF THE ROTARY DESICCANT SYSTEM
USING THE CROMER CYCLE

By

Bronislava Veltcheva

May 2003

Chair: Yogi Goswami
Major Department: Mechanical and Aerospace Engineering

The main objective of this study is to test (under field conditions) the feasibility

and effectiveness of the Cromer cycle. When cooling a space to a comfortable condition

there are two types of loads to be removed: the temperature-associated load (sensible

load) and the moisture-associated load (latent load). Conventional vapor-compression

air-conditioning systems perform well when the latent load is 25% of the total load or

less. In many applications (such as geographical locations with hot and humid climates,

restaurants, supermarkets, etc.) the latent load often is higher. In such cases, the

conventional air conditioning system fails to meet the increased latent load.

The Cromer cycle uses a desiccant for enhanced dehumidification of the air. It is

based on installation of a desiccant wheel to transfer heat and moisture between the return

and supply side of an air handler. The unique feature of the Cromer cycle is that

regeneration of the desiccant is accomplished by the return air (not by an external heat

source).









To test the Cromer cycle under field conditions, the existing air-conditioning

system of a residential house was retrofitted to accommodate a desiccant wheel. The

wheel was alternately switched in and out of the system. Data for the performance of the

system were collected and compared for the standard and the Cromer configurations. To

screen out any changes due to the ambient conditions only, another house located close to

the Test house was also instrumented and monitored.














CHAPTER 1
INTRODUCTION

Air conditioning (AC) is the process of providing by mechanical means control of

temperature, relative humidity, movement and purity of the air.

Maintaining a space at a desired indoor condition may be achieved by simple

heating (increasing the dry bulb temperature), simple cooling (lowering the dry bulb

temperature), humidifying (adding moisture), or dehumidifying (removing moisture) the

air. Quite often two or more of these processes are required to bring a space to the

desired condition.

To maintain the desired comfort conditions an air conditioning system has to

handle two loads. These are the temperature associated, or sensible load and moisture

associated, or latent load. The sensible load is met simply by changing the dry bulb

temperature of the air. To meet the latent load of the space some moisture has to be

added or removed from it. There are four principal methods [Jones 2001] of

dehumidification:

* Cooling air to a temperature below its dew point

* Adsorption

* Absorption

* Compression followed by cooling.

The conventional vapor-compression AC system meets the latent load of the

space by cooling the air below its dew point and as a result water vapor is condensed

from the air.









1.1 Why Air Conditioning

Air conditioning has grown rapidly around the world. As shown in Table 1-1

[Energy Information Administration 2000] in the last twenty-five years more Americans

have air conditioners in their homes and use their AC equipment more often.

Furthermore nowadays almost all automobiles are equipped with AC systems.

Table 1-1. Use of air conditioning equipment in the USA households (percent of
households)
Survey Number of Percent with Percent with Percent with
year households central air window/wall air no air
(million) conditioning conditioning conditioning
National
1978 76.6 23.0 32.8 44.2
1979 77.5 24.1 30.7 45.1
1980 81.6 27.2 30.0 42.8
1981 83.1 26.9 31.3 41.8
1982 83.8 27.9 30.2 41.9
1984 86.3 29.7 29.9 40.4
1987 90.5 33.9 29.8 36.4
1990 94.0 38.9 28.8 32.3
1993 96.6 43.5 24.9 31.6
1997 101.5 47.1 25.4 27.5
South
1978 24.6 36.9 37.7 25.5
1979 24.9 38.5 33.8 27.7
1980 27.0 41.4 32.7 26.0
1981 27.7 42.6 34.0 23.4
1982 28.1 42.1 33.7 24.2
1984 29.3 47.3 29.8 22.8
1987 30.9 52.3 29.9 17.9
1990 32.3 59.0 28.2 12.9
1993 33.5 65.1 24.1 10.8
1997 35.9 69.7 23.2 7.0
Energy Information Administration (EIA), 2000. URL:
http://www.eia.doe.gov/emeu/consumptionbriefs/recs/actrends/recs ac trends.html.

In most commercial and residential applications, the humidity in the space is not

directly controlled. Rather it is controlled only indirectly; and increases or decreases as a

result of changes in the match between the sensible and latent capacity of the AC









equipment compared to the sensible and latent loads of the space. A conventional AC

equipment performs well when sensible load is 75% of the total cooling load or higher

[Kosar et al. 1998, p.72]. There are many applications, however, where the latent load is

higher than 25%. Geographical locations such as Florida, where the weather is hot and

humid for many months throughout the year; supermarkets with big display cases; and

restaurants are among those applications. In such cases, the conventional AC unit often

fails to meet the comfort conditions. This results in elevated indoor humidity levels,

discomfort, and mold and mildew growth.

1.2 Desiccant Cooling Concept

Use of desiccants is one solution to the problem of high humidity. Desiccants are

materials that have an affinity for water. While conventional AC equipment controls

humidity by condensation on a cold surface, desiccant-based systems dehumidify by

adsorption or absorption in a hydroscopic material. The process of attracting and holding

moisture is described as either adsorption or absorption, depending on whether the

desiccant undergoes a chemical change as it takes on moisture. Adsorption does not

change the desiccant, except by the addition of the mass of water vapor; it is similar to a

sponge soaking up water. Absorption, on the other hand, changes the desiccant

chemically or physically.

Two basic types of desiccants are used: solid desiccants (e.g., silica gels, zeolites

and synthetic polymers) and liquid desiccants (e.g., salt solutions and glycols). All

desiccants function by the same mechanism transfer of moisture due to a difference

between the water vapor pressure at desiccant surface and the surrounding air. The vapor

pressure of water at the desiccant surface depends on the physical characteristics of the









desiccant, the temperature of the desiccant, and the amount of water adsorbed in the

desiccant. When the vapor pressure at the desiccant surface is lower than that of the air,

the desiccant attracts moisture. When the surface vapor pressure is higher than that of the

surrounding air, the desiccant releases moisture. Equilibrium is reached when the vapor

pressure in the desiccant is equal to that in the air. To allow repeated use of the

desiccant, it has to be regenerated. Regeneration usually is accomplished by heating the

desiccant using an external heat source.

Most desiccant cooling systems use a desiccant to handle the latent load before air

goes to the cooling device. The desiccant material picks up moisture from the air before

the air is sensibly cooled. This way it is not required to cool the air excessively in order

to condense moisture from it.

The literature provides extensive overviews of work showing the effectiveness

and energy-saving potentials of desiccants [Pesaran et al. 1992, Oberg 1998, Mago and

Goswami 2001].














CHAPTER 2
CROMER CYCLE

The Cromer cycle is a desiccant-based technology for enhanced dehumidification

of the air. It is based on installing a desiccant wheel between the return and supply air

streams in an AC system to transfer heat and moisture between the two streams. Unlike

other desiccant-assisted cooling technologies, the Cromer cycle does not require external

heat source to regenerate the desiccant, but relies on inherent vapor-pressure differential.

A general layout of an air handler equipped with the Cromer cycle is shown in figure 2-1.

A schematic of the wheel operation is given in figure 2-2. The processes that air

undergoes when passing through the wheel are as follows: cold air with very high relative

humidity (RH) leaves the cooling coil and passes through the working side of the wheel,

cooling the desiccant and transferring moisture to it. At the same time, the warmer air

with lower RH from the conditioned space passes through the return side of the wheel,

absorbing moisture and regenerating the desiccant. The release of moisture into the air

returning from the space before it enters the cooling coil increases the latent ratio of the

coil, enhancing its dehumidification abilities. The RH and temperature difference of the

two air streams provides the potential for moisture transfer. The feature of Cromer cycle

technology that distinguishes it from other desiccant-based concepts is that the return air

(rather than an external heat source) accomplishes regeneration of the desiccant.

To show the differences in the cooling process between the standard AC cycle

and the Cromer cycle, the corresponding state points of the air are shown on a

Psychrometric chart (Figure 2-3).









Air Handler


Desiccant Wheel


Figure 2-1. General layout of the AC handler equipped with the Cromer cycle
Working side


Cold and high RH air
from air handler


Slightly warmed and
dehumidified air to space


Iva


Cooled and humidified
air to air handler


Warm and low RH
air from space


Regeneration side


Figure 2-2. Desiccant wheel operation


Cost Increase Since 2006










Point 1 is the state point of the air that returns from the conditioned space. For the

standard air conditioner configuration, the air at state 1 enters the cooling coil where it is

cooled down and dehumidified. Point 4" depicts state of the air as it leaves the coil.

This point represents the temperature and moisture content of the air that is supplied to

the conditioned space by the standard AC system. The Cromer cycle is depicted in the

same figure with the solid line passing through points 1 to 4. The desiccant adsorbs




2



4"3 ------------- ----
S.. 4's


3 -.--.--------------------- ---- 4'c
4


I I I |
5 10 15 20 Temperature [C]

Figure 2-3. Psychrometric chart of standard AC cycle and the Cromer cycle.
1 = return air, 2 = air before cooling coil, 3 = air after cooling coil, 4 = supply
air (Cromer cycle), 4's and 4'c = calculation points, 4" = supply air (standard
configuration)

moisture from the cold and high RH air leaving the coil. This sorption of

moisture dries the supply air before it goes to the space, and follows the line between

state points 3 and 4. The moisture adsorbed by the desiccant is then re-evaporated into

the return air before it reaches the cooling coil. The process between state points 1 and 2









represents this process that also regenerates the desiccant. The process between points 2

and 3 depicts the work performed by the evaporator cooling coil.

2.1 Parameters That Impact Cromer Cycle Performance

The desiccant wheel is the heart of the Cromer cycle. There are number of

parameters that have significant impact on the performance of the wheel and from there

on the Cromer cycle. Zhang and Niu [2002] found three key parameters:

* Desiccant isotherm shape

* Maximum desiccant matrix moisture uptake

* Heat and mass transfer characteristics of the matrix.

Depending on these parameters but as well as on the operation conditions, the best

for the corresponding application geometry of the wheel, size of air passage channels, air

flow rate and speed of rotation can be chosen.

2.1.4 Solid Desiccant Materials Isotherm Shape

Adsorption behavior of the solid desiccants depends on:

* Total surface area

* Total volume of capillaries

* Range of capillary diameters.

A large surface area gives the adsorbent a larger capacity at low relative

humidities. Large capillaries provide a high capacity for condensed water, which gives

the adsorbent a higher capacity at high relative humidities. A narrow range of capillary

diameters makes the adsorbent more selective in the vapor molecules it can hold. The

desiccant isotherm characterizes how a desiccant material picks up moisture at different

levels of RH. Different desiccant materials exhibit different isotherm shapes. Since the










adsorption behavior of the solid desiccants depends on the surface characteristics of the

desiccant and the geometry of the internal structure, they can be engineered and

manufactured to produce a variety of isotherm shapes. Figure 2-4 [ASHRAE 1997]

illustrates this point using three silica gels adsorbent materials.


I I I I
160 -


140 -

GEL I
120











40 -
GELS8




0 20 40 60 80 00
RELATIVE HUMIDITY, % at 22C

Figure 2-4. Adsorption characteristics of some experimental silica gels
(ASHRAE Fundamentals 1997, Fig.6, p.21.4)


The Cromer cycle application requires the desiccant to adsorb moisture from air

coming off the coil that is cold and close to saturation and desorb moisture to air that is

warmer and at a lower RH. The desiccant is regenerated by the vapor pressure

differential inherent in the RH differences rather than heat or temperature difference.

Therefore, desiccant materials with isotherms similar to that of Gel 1 (Figure 2-4) are

required.









2.1.2 Desiccant Matrix Moisture Uptake

Desiccant matrix moisture uptake is defined as the moisture adsorbed by a

desiccant at 100 % RH per unit mass of desiccant material. The larger the maximum

desiccant moisture uptake, the longer the adsorption and regeneration process times.

2.1.3 Number of Transfer Units

Larger number of transfer units (NTU) means more efficient heat and mass

transfer within the desiccant wheel. The optimal performance of a desiccant wheel

versus the desiccant wheel NTU is similar to the maximum desiccant moisture uptake.

The adsorption-side outlet humidity decreases with NTU. Therefore the performance

improves by increasing the NTU. Zheng et al. [1995b] discussed the importance of NTU

and ways to modify it.

2.1.4 Speed of Rotation
The rotational speed of a desiccant wheel is the number of rotations that it

undergoes per unit time. This speed determines the length of time the desiccant stays in

the adsorption process as well as the length of time it is regenerated. Many authors note

that wheels used for air dehumidification are more sensitive to the speed of rotation

compared to those for enthalpy recovery. The desiccant wheel must be operated at a

optimum rotational speed to maximize the dehumidification performance and therefore

the rotational speed is a critical parameter for optimization [Zheng et al. 1995a].

Depending on the application and the parameters of the wheel the correct speed is to be

found to provide the optimum heat and mass transfer. When a desiccant wheel rotates

much faster than the optimum speed, the adsorption and regeneration processes are too

short which results in a poor performance. Similarly if the rotary speed is lower than the

optimum then the adsorption and regeneration processes are too long and more energy is









wasted in sensible heating/cooling than in the sorption process and therefore is less

effective.

2.2 Literature Review

The main feature of the Cromer cycle that differentiates it from the conventional

air conditioner is that "the dew point (moisture content) of the incoming air is

substantially increased by the transfer of moisture to the air before it reaches the cooling

coil. An increased average coil temperature results in improved energy efficiency over

prior methods of sensible heat transfer for dehumidification enhancement and in

increased dehumidification over a conventional air conditioner." [Cromer 1988, p.4]

There are several theoretical analyses of the cycle performance in the literature.

Nimmo et al. [1993] developed a simulation model that calculates the air conditioner

Energy efficiency ratio (EER) as a function of the Sensible heat ratio (SHR). They use

that model to compare the performance of the Cromer cycle with that of heat-pipe-

augmented, single-speed air conditioner and an air conditioner with a variable speed

supply air fan. The simulation results indicate feasibility of the cycle. When compared

to the other dehumidification alternatives, the Cromer cycle maintains a higher EER over

a wide range of SHR values.

Rengarajan and Nimmo [1993] carried out a parametric study. First the authors

compare the energy use, comfort (defined as the number of hours the space conditions are

within ASHRAE comfort zone) and the total cost (sum of capital costs and operation

costs) for single speed air conditioners and variable speed air conditioners each assessed

with and without the addition of a desiccant wheel and heat pipes. The results from the

parametric study show that the AC equipped with Cromer cycle provides better comfort









at low energy use and at a lower total cost. Furthermore the authors evaluate the energy

saving potential of the Cromer cycle by comparing it to a high efficiency air conditioner.

The authors show that the high efficiency AC has higher efficiency and consumes less

energy than the Cromer cycle. When, however, the two are forced to maintain the

ASHRAE comfort conditions for applications with high latent load for example, Miami

the Cromer cycle consumes 10 percent less energy.

Results from a study of the Cromer cycle bench test prototype under laboratory

ARI test conditions are reported by Cromer [1997] (Table 2-1).

Table 2-1 Performance of a standard AC handler compared with an AC handler with the
Cromer cycle
Standard AC AC unit with Improvement
unit Cromer cycle %
Operational capacity [Btu/hr] 53,590 66,328 23.8
Latent cooling [Btu/h] 14,017 35,425 152.7
LHR [%] 26.2 53.40 103.8
Dehumidification [gal/h] 1.56 3.93 153.2
Watts (over test hour) 6709 5610 16.4
EER 7.99 11.82 47.9

(Cromer 1997, Cromer cycle: An energy efficient solution to indoor air quality problems.
Engineering Solutions to Indoor Air Quality Problems, p. 294)

2.3 Objectives of the Present Study

The theoretical studies and the laboratory test results published in the literature

show that for high latent load applications the Cromer cycle is significantly superior

compared to the standard AC configuration. Published literature shows that the Cromer

cycle technology enables the evaporator coil to meet higher latent loads and it achieves

that at reduced energy consumption.









If similar behavior can be verified under field conditions the system could

contribute to significant energy savings, while providing better indoor conditions.

The purpose of this study was to test the feasibility and effectiveness of the

Cromer cycle technology under field conditions. To test the performance of the Cromer

cycle in field conditions the following was done:

* Two residential houses, located close to each other were equipped with the
necessary instrumentation. The existing residential AC system of one of the
houses, called Test house, was retrofitted with the Cromer cycle equipment, while
the AC system of the second house, called the Reference house, was kept in the
standard vapor-compression configuration;

* The Cromer equipment was alternately switched in and out of the AC system of
the Test house. Data for the performance of the AC unit in its standard
configuration and with the Cromer cycle attached were collected;

* Indoor conditions maintained in the Test house by the AC in its standard
configuration and with the Cromer equipment were compared;

* Several performance characteristics as Q total, Q sensible, Q latent, LHR and
apparent energy efficiency ratio were calculated and compared for the standard
and the Cromer configurations in the Test house.














CHAPTER 3
EXPERIMENTAL SETUP

For the purposes of the present study an existing residential air conditioning unit,

located in the Solar House in the Solar Energy and Energy Conversion Laboratory

(SEECL), Gainesville, Florida was chosen. A number of developments that are now used

worldwide originated there. As recognition of their important role the SEECL and the

Solar House were designated as a Mechanical Engineering Heritage Site in January 2003.

3.1 Experimental Facility

The Solar house (figure 3-1) has 0.23m hollow concrete block walls, a double

wood floor and an asphalt shingle roof. The house encloses approximately 110 m2 of


Figure 3-1. Test house









living space and is orientated East-West. There is no additional insulation added on the

walls. There is fiberglass bat, R-11 insulation over the conditioned space. The AC

distribution duct system of the house is located in the attic, directly above the conditioned

space.

The conventional AC system in the Solar house is a vertical GrandAire three ton

high efficiency air conditioner condenser unit model GS3BA-036KA with matching

GrandAire air handler GB3BM-036K-A-10 model. This is a direct expansion R-22 AC

system.

3.2 Measuring Instrumentation

For the objective of the study, the Test house, thereinafter interchangeably

referred as Solar house or Test house, was instrumented with measuring devices to

monitor and record the desired variables.

Temperature and RH measurements were provided by combined sensor

transmitters, manufactured by Vaisala Co. HMD60W sensor/transmitter was used to

measure the inside RH and temperature. Ambient conditions were monitored by

HMD60YO. HMD60Y sensors were used to measure the corresponding temperatures

and relative humidities of the return air before the desiccant wheel and the AC handler

and of the supply air at the exit of the AC handler and after the wheel. A schematic of

the sensors locations in the duct system is given in figure 3-2. All Vaisala

sensor/transmitters were installed with the factory calibration, specified to be 0.3oC for

the temperature readings and 2% for the RH readings. Periodically, however, the

outside RH sensor was recalibrated because of problems with condensate formation.










3





2 1








Figure 3-2. Location of the combined temperature and RH sensors

Energy consumption of the AC unit was measured using watt-hour transducer

Model WL40R-052, manufactured by Ohio Semitronics Inc, Ohio. Energy consumption

of the wheel was measured separately using a watt-hour transducer Model WL40R-049,

manufactured by the same company. Both transducers were installed with the factory

calibration which is specified to be 0.5% of full scale. The pulse pick up of the watt-

hour transducers provides a pulse for every 10Wh consumed.

Air flow measurements were provided by using a hot wire anemometer,

manufactured by Comark Ltd. Its accuracy is specified to be 3% of the reading.

A data acquisition system based on LABTECH software was setup to acquire the

signals from the corresponding measuring equipment. A program was designed to scan

each probe every 5 seconds, then the readings were averaged for each 20-second-period

and recorded in a file.

Another house, named the 'Reference' house for this study located next to the

Test house, was monitored to be used as a 'control'. Though the reference building

(figure 3-3), is located very close to the Test house, it is not the same. It is larger-









approximately 180 m2 (as compared to 110m2 test house), oriented North-South, has

different glass area and uses 3 ton Trane condenser and air handler.
























Figure 3-3. Reference house

Despite the differences, however, when the indoor conditions of the two houses

were compared it was established that the humidity levels maintained by the

corresponding conventional AC systems were quite similar. Therefore it was decided

that this Reference house could serve as a 'control' for the purposes of the study. Since

the ambient conditions vary, collecting data from this Reference house would provide an

additional control comparison. Monitoring simultaneously the Reference house, where

no changes are made and the Test house would make it possible to estimate to what

extent the different comfort conditions maintained in the Test house with the Cromer

technology, are due to enhancing the AC unit with the Cromer equipment as opposed to

the changes in the ambient conditions. If with the Cromer cycle considerable decrease in









the RH levels is observed but the same trend is observed in the Reference house also then

the reason could be favorable ambient conditions rather than the Cromer equipment. If

however, in the Test house considerable changes in the indoor conditions are observed

between the standard configuration and the Cromer cycle while in the Reference house

the indoor conditions are maintained the same, then it could be concluded that the

changes were due to the Cromer cycle.

The Reference house was equipped with HMD60W sensor/transmitters for

monitoring the inside temperature and RH and with a WL40R-052 watt-hour transducer

for the AC energy consumption measurement. The monitoring system of the Reference

house was connected to the data acquisition system of the Test house.

3.2 Desiccant Wheel

The desiccant wheel, used in the present study, was manufactured by

AirXchange Company, Rockland, MA. It was 0.075m wide, 0.94m diameter and

consisted of 6 removable segments.

3.2.1 Desiccant Material

In the study two types of desiccants, called Desiccant A and Desiccant B, were

tested. The first test was conducted with Desiccant A material the typical enthalpy

wheel desiccant that AirXchange company uses for their enthalpy wheel products. The

desiccant wheel had flat laminate segments structured in an ideal parallel plate geometry.

The laminates were arranged continuously with one flat and one structured layer (Figure

3-4 (A)). The structured layer had small conical internal dimples to separate the

laminates and define the geometry of the matrix. For the second and the third test the

segments were replaced with laminates that were not flat but waved. The waved



























Figure 3-4. Laminates design. (A) Flat laminates. (B) Waved laminates.

segments had axial ridges (Figure 3-4 (B)) to determine the geometry while providing an

obstruction for the air carryover from one side of the wheel to the other. The new

segments laminates were coated with different silica gel, called desiccant type B. The

second desiccant type was suggested by Dr. Cromer. Under laboratory conditions the

inventor had tested several types of desiccants and found type B one to have superior

performance for Cromer cycle applications.

3.2.2 Speed of Rotation

In the current study the Cromer cycle performance was tested with the desiccant

wheel rotating at two different speeds:

* 10 revolutions per hour-a speed of rotation found to be the optimal in theoretical
simulations [Nimmo et al. 1993]. It is to be admitted, though, that this rotational
speed was found optimal for a different desiccant type;

* 42 revolutions per hour-determined by Dr. Cromer, based on laboratory tests of a
desiccant wheel with segments, coated with type B desiccant.









3.2.3 Wheel Accommodation

Since desiccant wheel transfers moisture between the return and supply air

streams, the important moment in retrofitting an existing AC system with the Cromer

cycle is to reorient the air in order to direct the air flow through the wheel (Figure 3-5).


Figure 3-5. The experimental wheel assembly

The original setup of the air handler in the Solar house in the standard AC

configuration was that the air handler was taking return air directly from the space being









conditioned via a short straight duct connected to a return air grille. Another short and

straight duct connected the air handler supply side to a plenum box from which a spider

type distribution system brought the air to each room of the house. In its standard

I,.


Figure 3-6. The experimental setup









configuration the existing vertical air-handling unit in the Solar house fitted in lxlx2m

(length by width by height) space. In order to connect the wheel without modifying the

distribution system, but at the same time to avoid any sharp turns, the retrofitted

configuration took a 3.5xl.5x3m space (Figure 3-6).

There was information that in previous tests certain slipping had been observed

(the belt that drives the wheel skided on its surface, thus changing its speed of rotation).

In order to avoid that, in this study the flat belt that originally came with the wheel was

replaced by a grooved belt (Figure 3-7).























Figure 3-7. The pulley and the driving belt

A mechanism (Figure 3-8) was designed for monitoring the number of rotations

of the desiccant wheel. Tests showed that with the new belt the problem of the belt

slipping on the wheel's surface was eliminated.






























Figure 3-8. Mechanism for monitoring number of desiccant wheel revolutions


3.2.4 Power Supply of the Desiccant Wheel

The desiccant wheel is supposed to rotate only when air is blowing in the AC

system. This requirement was achieved by connecting the motor of the wheel to the

power supply via a relay as shown in the Figure 3-9.


Relay


FUSE


Wheel's
Electric Motor
120V/AC


Neutral


Figure 3-9. Desiccant wheel power supply layout


Blower
Motor
240V/AC









3.3 Condensate Measuring Equipment

During the field study it was recognized that it would be useful to measure

automatically the water condensed by the cooling coil. For the purposes of the present

test, a system was designed to measure the volume of the condensed water. The

schematic of the system and a picture of the condensate collecting part are given in

figures 3-10 and 3-11 respectively. The equipment was connected to the data acquisition

system and was designed to send a pulse for each 110ml of water removed by the cooling

coil.




Level Sensor Relay o
STimer 120V/AC

S FUSE Neutral
Level Magnet ------------------- ---





Solenoid
Valve
120V/AC




Figure 3-10. Condensate measuring equipment

3.4 Data Acquisition System

A data acquisition system (Figure 3-12) based on LABTECH software was setup

to acquire the signals from the corresponding measuring equipment. The program was

designed to scan each probe every 5 seconds, then the readings were averaged for each

20-second-period and recorded in a file. Since all variables were recorded at each 20-









second-period, data collected are very detailed and made it possible to obtain information

about beginning and end of each cycle, its duration, state points of the air before and after

the wheel both on its working and regeneration side, condensate removal, and the exact

energy consumption.


Figure 3-11. Condensate measuring vessel and valve
















+17V

-- 4-20mA |-----------------------
S4-20 4-20mAA





alog Signals ul= 1-5V I

+17V TTL Level
Current to TTL M In1
4mA Conver In3 Counter
20mA 4mAI = Log. 0- Cu
20mA= Log.1 "

Data Acquisition System

Digital Signals
+17V


Figure 3-12. Layout of the data acquisition system


An


-------------


_I














CHAPTER 4
PROTOCOL AND EXPERIMENTAL RESULTS

4.1 Protocol

An experimental protocol was developed to study operation of the AC system

when retrofitted with the Cromer cycle equipment. It has to be noted that no attempt was

made to achieve operation under ARI conditions. The goal was to test the performance

of the Cromer cycle in field conditions.

All data, collected for the periods of operation of the air handler as a conventional

AC unit, were collected in a baseline set. The data for the periods, when the AC system

was enhanced with the Cromer cycle, were collected in the Cromer set. Cromer set

includes several data sets because Cromer technology was tested with different desiccant

types and at different speeds of rotation of the desiccant wheel.

The protocol involved alternate switch of the Cromer equipment in and out of the

AC system of the Solar house. Since ambient conditions change alternated switch made

it possible to obtain data both for the baseline set and for the Cromer set under variety of

ambient conditions.

As already mentioned in Chapter 3, during the first test the wheel was rotated at

10 rph, a speed found to give optimum performance for the Cromer cycle under computer

simulations [Nimmo et al. 1993]. The second test was conducted with the wheel rotating

at 42 rph, a speed that the inventor found to be the optimum under laboratory test of a

wheel, covered with type B desiccant. For the third test conducted with the second wheel

and type B desiccant, the speed of rotation was reverted back to 10 rph in order to check









how it would influence the overall performance and if this would reduce the heat

recovery from what was observed in the preceding test.

Before the beginning of each field test, the system was run in its standard vapor-

compression configuration. For the first test the thermostat was set at 220C and the

blower was set at low speed. The baseline test was run for a week. After that the Cromer

cycle equipment was installed. The Cromer technology was tested with the desiccant

wheel, consisting of flat laminate segments, coated with desiccant type A and with a

wheel rotation speed of 10 rph. The tests were conducted for a two-week period and

under the same settings as the preceding baseline test. The data were collected in the

Cromer set and stored as "set No. I1".

For the next test the Cromer configuration was disconnected and data collected

for the operation of the AC system in its standard configuration again. The test was

conducted for two weeks, the thermostat set at 240C and the blower speed at medium.

After this two-week period, the Cromer cycle was connected again. This time, however,

the performance was tested with waved laminate segments, coated with desiccant type B

and at a speed of rotation of 42 rph. Under the settings of 240C and medium fan speed

the test was run for a two-week period and the data collected in the Cromer set as "set

No.2".

The next step was to switch the Cromer configuration out of the system for 10

days so as to collect more data for the baseline set. After this 10-day-period the Cromer

configuration was connected in the system again. The new test was conducted for 4

weeks. During this test the settings, as well as the desiccant wheel, were the same as in









"set No.2" tests. The only difference was that the rotational speed of the wheel was

reverted back to 10 rph. Data from this test were stored in the Cromer set as "set No.3".

Appendix A contains tables for all data sets collected. Each table presents

summarization of the ambient conditions, duration of operation, condensate removal and

energy consumption of the corresponding AC systems in the Test house and in the

Reference building.

The detailed data sets include extended tables for every day. These extended

tables give information about the ambient conditions, the indoor conditions, temperatures

and relative humidities at different places of the return and supply air ducts, number of

cycles of operation, duration of each cycle, condensate removed by the coil and energy

consumption of the AC units both in the Solar house and in the Reference building. These

detailed tables are available on a compact disk.

4.2 Experimental Results

4.2.1 Baseline Set AC Unit in Standard Configuration

Data, collected during the periods when the AC system in the Solar house was

operating in a conventional cycle, are presented in the baseline data set and used for

comparison.

Plots of the typical indoor RH levels maintained in the Solar house and in the

Reference building during the periods when the AC systems in both houses were

operating in the standard vapor-compression configuration are illustrated in figure 4-1.

As indicated, despite the differences between the size of the two houses and the different

AC equipment, the inside RH levels maintained in the Test house were found to be

similar to the inside RH levels maintained in the Reference house, and somewhere in the

range of 45-50%.


















60

50

40

30

20


A











1 3 5 7 9 11 13 15 17 19 21 23
Time of day


C


/U
/u -----------------

60

50

7 40

30

H- r^


1 3 5 7 9 11 13 15 17 19 21 23
Time of day


D


50
== 50


7 40
-
30

20


1 3 5 7 9 11 13 15 17 19 21 23
Time of day
-o-T in Test house
-*-RH in Test house


1 3 5 7

-oT in Reference hot
-- RH in Reference hoL


9 11 13 15 17
Time of day


19 21 23


Indoor temperature and RH profiles from Baseline set. (A) 09/18/2001. (B) 09/20/2001. (C) 06/10/2002.
(D) 08/05/2002.


Figure 4-1.










4.2.2 Set No.1 -Cromer Cycle Configuration with the Desiccant Wheel Using Flat
Laminate Segments and a Rotational Speed of 10 rph

The immediate observation, after conducting this first test of the retrofitted AC

system, was that installation of the desiccant wheel introduced a considerable increase of

the pressure drop in the AC system. This resulted in 35% decrease in the airflow rate (the

mass flow rate dropped from 1680 kg/h down to 1080 kg/h). Another observation was

that with the wheel in place there was an increase in the average operational time of the

air conditioning system.

Since in Cromer configuration the desiccant wheel transfers moisture and heat

between the high pressure side and the low pressure side of the wheel, with the radial and

flat design of the laminates a significant re-circulation of air from supply to the return

side of the wheel was observed. Physically it was easy to feel this re-circulation but it

was not quantified mathematically. Calculations were conducted to quantify the amount,

but because of the considerable uncertainty involved, no precise value could be given.

With regard to the ability of the retrofitted AC system to improve the indoor

conditions, this data set is not very persuasive. Most of the time the Cromer cycle system

was maintaining indoor relative humidities in the range of 45-50% as did the

conventional arrangement. There were days though, when for a limited time during the

day the inside RH levels were below 40%. Review of the data shows that these were the

days when the AC system was operating for more than 5 hours a day. It was felt that the

reason for the inconclusiveness of any enhancement of performance by the Cromer cycle

was because the tests were conducted in the month of October when the ambient

temperatures were lower. The thermostat setting was satisfied for longer periods and

under these circumstances run-time fraction of the air conditioner was low.









For more detailed evaluation of the AC performance, pairs of days with similar

ambient conditions from the baseline set and the Cromer set were chosen and compared.

Days in each pair were chosen based on meeting the following criteria:

* Ambient conditions within each pair were very similar

* Average ambient temperatures were high throughout the day.

The following parameters were calculated:

Total cooling capacity Q0toal = i(h, h4, [kJ/h] (4-1)

Sensible cooling capacity Qen.ble = h(h h4), [kJ/h] (4-2)


Sensible heat ratio SHR Q= .en.ble (4-3)
Total

Latent cooling capacity Qiatent = h h4 ), [kJ/h] (4-4)


Latent heat ratio LHR = Qatent (4-5)
Total


Apparent energy efficiency ratio1 EERapp= Qt0tal h (4-6)
Powerlnput W

where hi, h4 and h4' (Figure 2-3) are the enthalpy of the return air, enthalpy of the supply

air and enthalpy of a condition when the air is at the temperature of the return air but with

the humidity ratio of the supply air. The symbol iM 'is used for the mass flow rate of the

air.

As an illustration, the results for two such pairs are presented. The ambient

conditions during those pairs of days, the corresponding run times of the systems in the




1 The energy efficiency ratio is defined as "Total cooling/Power input" under standard ARI conditions.
Here EER was estimated under field conditions, therefore it was called EERapp.









two houses monitored and the condensate removed by the air handler in the Test house

are shown in table 4-1.

Table 4-1. Ambient conditions and run times for the data pairs from the baseline set and
Cromer set No.1
A B C D E F
Date T amb >25C T amb >28C RH TH Ref.H Conden
amb. duration duration sate
hours 0C hours 0C % hours hours liters
Baseline 9:50 28.24 6:15 28.74 53.28 6:04:40 9:55:40 21.9
09/17/01
Cromer 10:10 28.79 6:55 29.85 55.09 7:42:38 8:36:19 25.2
10/05/01
Baseline 12:00 28.62 7:10 29.05 65.59 9:13:40 11:45:40 24.6
09/19/01
Cromer 11:35 28.28 6:35 29.42 71.10 10:46:40 10:02:43 30.3
10/06/01 ______ 1 111 1 1

A = Time when ambient temperature was above 250C. Left sub column denotes number
of hours ambient temperature was above 250C. Right sub column denotes the
average ambient temperature during that time.

B = Case where ambient temperature was above 280C. Left sub column denotes number
of hours ambient temperature was above 280C. Right sub column denotes the
average ambient temperature during that time.

C = Average ambient RH during the time of day when the ambient temperature was
above 250C.
D = Duration of operation of the AC unit in the Test house.

E = Duration of operation of the AC unit in the Reference house.

F = Amount of water removed from the air by the AC coil in the Test house.


Cromer cycle resulted in more water removal from the air. The average

operational time, however, was increased. Data show that, when the systems in the Solar

house and in the Reference house were both in standard configuration, on average it took

30% longer time for the air conditioner in the Reference house to meet the thermostat

setting. When, however, the Cromer equipment was installed in the Solar house, this









difference in the operational times was reduced. Furthermore, days were observed when

the operational time of the AC system in the Test house was longer than the

corresponding time in the Reference house.

Comparison of the temperatures and relative humidities, maintained in the Solar

house and in the Reference house are given in figure 4-2. The calculated performance

parameters for the AC system in the Solar house are presented in a graphical form in

figure 4-3. Each point on the plots represents the average for one run period of the AC

unit. It has to be noted that since the sensor used to measure the temperature and RH

after the coil was located after the fan, the measurements include the additional heat

generated by the fan motor. Therefore, the cooling calculated here is less than the actual

cooling performed by the cooling coil. To facilitate the calculations a Fortran program

for calculation of the performance characteristics was developed. The print of the

program developed is given in Appendix C. The program used a link to the software

package PROPATH (PROgram PAckage for THermophysical properties of fluids),

courteously given for use to the SEECL by the PROPATH Group [Propath Group

2001].

The states and the corresponding cooling processes of the air in the Solar house

are plotted on Psychrometric charts in figures 4-4 and 4-5. For plotting the charts an

ASHRAE Psychrometric Chart software was used [Hands Down Software group 1992].

In these figures the states of the air when the system was in its standard vapor

compression configuration are depicted by the symbol 'S', where S 1 is the return air state

and S4 is the supply air state. The symbol 'C' depicts the states of the air when the AC

system was modified with the Cromer equipment. The state points are also depicted by









numbers 1 to 4, where '1' depicts return air state, '2'-state of the air after the desiccant

wheel on its regeneration side, '3'-state of the air as it leaves the AC handler, and '4'-

state of the supply air after the desiccant wheel, as depicted in figure 2-3.

As illustrated in figures 4-2 and 4-3, the following observations are made for the

Cromer configuration as compared to the standard configuration:

* Observed up to 50% increase in the latent heat ratio (latent cooling to total
cooling);

* Observed approximately 25% increase in the latent cooling;

* Observed approximately 15% decrease in the total cooling performed;

* Observed approximately 30% decrease in the sensible cooling;

* Observed 15% reduction in the apparent energy efficiency ratio; and

* RH levels maintained in the space are slightly lower.

Increase in the LHR and the latent cooling observed in the Cromer configuration

test, can be explained from the fact that the desiccant wheel desorbs moisture into the

return air before it reaches the coil. Therefore the air is wetter and closer to its dew point,

which switches the total cooling toward more latent cooling.

The observed decrease in the sensible cooling could be explained from the

reduced inlet air temperature and the reduced air flow due to the desiccant wheel. The

desiccant wheel reduces the temperature of the air before it reaches the cooling coil

because of evaporative cooling. However, when the corresponding initial and final states

of the air in the standard configuration are compared with the Cromer cycle on

psychrometric chart, it is observed that the enthalpy difference between the inlet and the



















60

50

40
[-


30

20


1 3 5 7 9 11 13 15 17 19 21
Time of day

70

60

50





30

20
1 3 5 7 9 11 13 15 17 19 21 23
Time of day
-o-Tin Test house
--- RH in Test house


-60
50



-40

H 30

20


1 3 5 7 9 11 13 15 17
Time of day


50




30






RH in- Reference house
3 0 ----------------


20 4---------------




RH in Reference house


Figure 4-2. Indoor temperature and RH profiles for Baseline set and Cromer set No. 1. (A) Baseline set-09/17/01.
(B) Cromer set-10/05/01. (C) Baseline set-09/19/01. (D) Cromer set-10/06/01.


19 21 23


19 21 23













30000


28000 --0 v ^0
0o 0.0
26000 -*

^ 24000 A

22000

20000
17 20 22 25 27
T amb [oC]
0.50

A




0.30 --
odA

0.20


0.10
30 35 40 45
RH in [%]


30 32 35


50 55 60

* 09/17/01 Baseline set
A 10/05/01 Cromer set


17 20 22 25 27
T amb [oC]


12000

10500 A

9000oo

A 04

/ 6000- -

4500

3000
30 35 40 45 50
RH in [%]
o 09/19/01 Baseline set
A 10/06/01 Cromer set


Figure 4-3. Comparison of performance characteristics. (A) Q total vs T amb.
(D) Q lat.vs RH in.


(B) EER vs T amb. (C) LHR vs RH in.


30 32 35


55 60














fTFN ASHRAE PSYCHROMETRIC CHART NO.1
NORMAL TEMPERATURE
BAROMETRIC PRESSURE: 101.325 kPa
Copyright 1992
AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS, INC.


SEA LEVEL


10-, ~
1.5-J


b.,tL uFar -


Baseline 09/17/01
Cromer 10/05/01


*-.. ~AJ
.-71 ~-~~ij~-* V~- 7
F. **-.--


-"' ..... .... .: ,-


_"-": _.'_... I k ,


'HU 0,1A. "

1,,, -'.V2_


1- 1
-"






1 _____
54
... : C2, _J ; ... ;' .. > .. i.
.." ..... ., .--:Ci .. I --__ . .' .. J : -- I. ; :


+ -,- .
i_ .-+ --- = --t. ... "...-._ -- . ..-=- -+-- -.. .. :--T --.. ..-:, .


-I-. -
-'----4~


I.


F.."-- -1-. -.. -,-
*- -- ~ ~~: '- '^ ..
. ..'-""^ i-..,' '- '"" ,:,


to0 ~? "*4
ENTHALPY KJ PER KILOGRAM OF DRY AIR
Figure 4-4. Psychrometric chart for similar days (Baseline set, 09/17/01 Cromer set No. 1, 10/05/01)


T -'-- "7-













/-F-1 ASHRAE PSYCHROMETRIC CHART NO.1
NORMAL TEMPERATURE
BAROMETRIC PRESSURE. 101 325 kPa
Copy right; 1992
AMERICAN SOCIETY' OF HEATING REFRIGERATijG iAND AIR CONDITIONING ENGINEERS aNC
SEA LEVEL


_. -" -_:_ _
.- ... ... {- I. .. -"4I
.. I ,, -..- ..... .. ....- . I, o
1. -,1+-: . . ... .--- .*~.. .


"," '.- -. -- ,- -. ... --
S_ ._ .-- -



Baseline 09/19/01 .._.
Cromer 10/06/01 I .. ... ". -





S '1

0 _7_
.. --' r--' -. ..7 "- ..'. ; "" -" ;- -






C3L
--

cS I -


-c7> _ _0I
~ .. .. . . . .. .. _


ENTHALPY KJ PER KILOGRAM OF DRY AIR


Figure 4-5. Psychrometric chart for similar days (Baseline set, 09/19/01 Cromer set No. 1, 10/06/01)


r






I.
.i-









outlet condition of the air is almost the same. The increased moisture of the air results in

a wetter coil that facilitates the heat transfer thus offsetting the negative impact of the

reduced air temperature on the heat transfer. Therefore the observed decrease in the

sensible cooling is mostly due to the dramatic decrease in the airflow rate, caused by the

introduction of the desiccant wheel. Anyway, for Cromer cycle applications it would be

better if the motor of the blower is located before the cooling coil. This way the heat

input of the motor would offset the pre-cooling of the air resulting from the air passing

through the regeneration side of the desiccant wheel.

Decrease in the sensible cooling exceeds the corresponding increase in the latent

cooling resulting in a decrease in the total cooling.

Decrease in the apparent energy efficiency ratio observed can be explained with

the reduction of the total cooling performed by the coil.

Decrease in the sensible cooling, performed by the evaporator coil, inevitably

increases the operational time of the AC system. Since only the thermostat setting

controls the air handler, for one and the same setting the Cromer configuration will take

longer time before it is able to satisfy the thermostat. Therefore the system equipped with

the Cromer cycle will operate longer and will have higher overall energy consumption.

With the Cromer cycle in place the RH of the air in the supply ductwork is

considerably lower. This way the requirement of the ASHRAE Standard 62 that calls for

maintaining the humidity in the ducts below 70% is accomplished, something that is

really very difficult to satisfy with the conventional AC vapor compression configuration.

Drier ducts prevent fungus and bacteria from growing so the space conditioned is at a

lower risk from such contamination.









4.2.3 Set No.2 Cromer Cycle Configuration with the Desiccant Wheel Using
Waved Laminate Segments and a Rotational Speed of 42 rph

In the Cromer set No.2 performance of the cycle was tested with new desiccant

segments for the wheel. The laminates of the new segments were coated with silica gel,

desiccant B type. In order to reduce the pressure drop the distance between the laminates

was slightly increased. The larger air channels, however, would increase the re-

circulation of the air from the high pressure to the low pressure side of the wheel. To

avoid that the new laminates were not flat as in the set No. 1 test but waved.

After replacing the segments with the new ones and converting two of the flexible

turns in the duct into rigid ones and setting the blower speed to medium small

improvement in the pressure drop in the system was observed. The volume flow rate

increased from 1080 kg/h to 1180 kg/h. This, however, was still below the specifications,

provided by the manufacturer of the air handler.

The test showed that under hot ambient conditions, the retrofitted AC unit

maintains considerably lower indoor RH levels. When compared to the humidity levels

with the standard configuration, it is seen that the Cromer cycle enables the conventional

AC system, in hot days, to achieve and maintain approximately 20% lower indoor RH

levels. Logically the more hours the unit works the more uniform the profile of the

humidity maintained. This test unambiguously verified that the Cromer cycle is able to

enhance the dehumidification, performed by the cooling coil.

Again pairs of days with similar ambient conditions from the baseline set and the

present set were chosen for more detailed comparison. Ambient conditions and duration

of operation of the AC system in the Test house in its standard configuration and with the

Cromer cycle for two such pairs of days are shown in table 4-2.









Table 4-2. Ambient conditions and run times for the data pairs from the baseline set
and Cromer set No.2
Date T amb >25C T amb >28C RH TH RefH Conden
amb. duration duration sate
hours 0C hours 0C % hours hours liters
Baseline 10:05 26.93 3:05 30.23 76.16 5:53:42 6:25:41 18.26
06/07/02
Cromer 10:30 27.43 3:55 28.67 72.30 7:40:59 6:43:00 30.03
06/26/02
Baseline 11:40 27.39 5:15 28.30 66.86 4:57:18 6:34:40 19.47
06/09/02
Cromer 11:05 27.88 6:00 29.06 71.11 7:23:38 6:56:21 27.17
06/27/02 111111


Cromer configuration resulted in increased water removal. The average

operational time of the unit, however, was also increased. Comparison between the data

collected in Cromer No.2 set and the data from the Baseline set for both houses show that

with the Cromer cycle the AC system in the Test house started operating at considerably

longer run cycles. Furthermore, when compared to the time of operation of the AC

system in the Reference house, it is seen that while under similar ambient conditions the

unit in the Reference house keeps its time of operation more or less the same, the

retrofitted unit in the Test house increases its time of operation.

Plots of the indoor conditions maintained are shown in figure 4-6. Figure 4-7

gives plots of the calculated performance characteristics of the AC system for the

standard configuration and for the Cromer cycle. State points of the air and the

corresponding cooling processes are plotted on psychrometric charts as shown in figures

4-8 and 4-9.

As with the Cromer set No. 1 test, here also similar positive and negative

consequences are observed. Only the magnitudes are different. Following observations

are made for the Cromer cycle:









* 35% increase in the latent heat ratio

* 45% reduction in the sensible cooling

* 30% reduction in total cooling

* 25% lower energy efficiency ratio.

In this test if look at the latent cooling by taking the average of the data it would

appear that Q lat is at the same order of magnitude for the standard and for the Cromer

configuration. This could lead to misleading conclusions. The reason for that is that the

Cromer cycle maintains much lower indoor RH than the standard configuration. If tests

were run when the inside RH were the same for the two configurations than the Cromer

cycle would provide considerably higher latent cooling as shown by the trend lines in the

corresponding Q,, = f(InsideRH) plots, given in Appendix D.

An important observation that came from this series of tests was that in field

conditions the speed of rotation of the wheel is very important for the heat transfer

ability. At a rotational speed of 42 rph the desiccant wheel recovered more heat. While in

Cromer set No. 1 test the supply air was injected into the space at a temperature

approximately 2C lower than in the standard configuration, in Cromer set No.2 the

opposite was observed. This increased heat recovery is clearly illustrated on the

corresponding Psychrometric charts on figures 4-8 and 4-9. Obviously the excess heat

recovery is undesirable for AC applications. It reduces the sensible cooling thus

increasing the time the system operates to satisfy the thermostat setting and from there

the corresponding overall energy consumption.

During this test, it was observed that when the AC came on after idle periods

longer than 6-7 hours, an unpleasant odor was introduced in the space in the first 2 to 3





























1 3 1 13 15 7
eo y


T o y


1 1 9 1


-o-T in Test house
--- RH in Test house


70

60

S50

40

30

20
1 3 5 7 9 11 13 15 17 19 21 23
Time of day
70

60

50

40

30

20
1 5 7 1 3


15 7 9 1 3 1
Ti of
---T in Reference house
-*-- RH in Reference house


17 19 21 23


Figure 4- 6. Indoor temperature and RH profiles for Baseline set and Cromer set No.2. (A) Baseline set-06/07/02. (B) Cromer set-
06/26/02. (C) Baseline set-06/09/02. (D) Cromer set-06/27/02.


1 3 5


.AAAAA1














33000


30000

, 27000

O 24000

21000

18000


20 22 24 26
T amb [oC]


28 30 32 34


20 22 24 26 28
T amb [oC]


14500

13000

11500

10000

8500

7000


30 33 36 39 42
RH in [%]


45 48 51 54


30 33 36 39 42 45
RH in [%1


* 06/07/02 Baseline set o 06/09/02 Baseline set
A 06/26/02 Cromer set A 06/27/02 Cromer set


48 51 54


Figure 4-7. Comparison of performance characteristics. (A) Q total vs T amb. (B) EER vs T amb. (C) LHR vs RH in.
(D) Q lat.vs RH in.


32 34


D




A o O


0 o 0 A






A A
A A A A I
AA A A A


L J














/--\ ASHRAE PSYCHROMETRIC CHART NO.1 /H-
< R NORMAL TEMPERATURE
19 BAROMETRIC PRESSURE: 101.325 kPa -
Copyright 1992 -- --
AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS, INC. ---

SEA LEVEL -- .








Baseline 06/07/02.. -
Cromer 06/26/02 .. ... --

c2 -

















ENTHALPY KJ PER KILOGRAM OF DRY AIR


Figure 4-8. Psychrometric chart for similar days (Baseline set, 06/07/02 Cromer set No.2, 06/26/02)














U/~-\ ASHRAE PSYCHROMETRIC CHART NO.1
/ S RAENORMAL TEMPERATURE 7 `Z
BAROMETRIC PRESSURE- 101 325 kPa .,--.....
Copyrign 1992 .. I
AMERICAN SOCIETY OF HEATING, REFRIGERATING 4.D AIR-CONDiTIOrdING ENGINEERS INC "" : -'

SEA LEVEL- -7 -. 7"-*.

1- --. o^- .--





Baseline 06/09/02 .-" *. _...... *----.- .' too
Cromer 06/27/02 ENTHA' -- .'-..
..HUM I I. "" ,", -.. "- / "" ".. "' '-" .











IP PR KILOGAM DRY AIR
Figure 49 Psychrometric chart for similar days (Baseline set 06/09/02 -Cromer set No 06/27/02)-
Cro me 061 7/0 ,. ." -4$4 -"--- i-- .-.. ;."-" I ." "... i ..... -
/.. .. .. .- ..:.. i f -. :. ... i . .. '- .. .
HUMIDITY' ,/ "' L'' "" / E ,.
.... .. .. I ..... ..t


._ ....._ ,-: .._! .- .. ; -..._._ ...... .. ..1

.._ .-- ; ,, .. .; .. .. ... . ...- ...4- -
.... .. ... .. i -- .. ; -' -t .... .. 7- -- q
t- U /-2-> cs 7, o -.. -,- -. ..;; -:- -: ,. ., :_ : :, : -
I-- % : -: .-- .:> -' l -r 1 . ., ... -- ..- r ," = -."3" "
--" ..--. .. -- : -- -, .. ... _,. =i- .. .. .. '- --' .. I- "' : ""- -= '- .. -" ="= ..' "" : -7









minutes of its operation. This could be explained with the desiccant material picking not

only moisture but other gases as well and evaporating them back.

4.2.4 Set No.3 Cromer Cycle Configuration Using Desiccant Wheel with Waved
Laminate Segments and a Rotational Speed of 10 rph

In this test the desiccant wheel had the same segments as in the set No.2. The

only difference was that the speed of the desiccant wheel was reduced to 10 rph. This

was done in order to check how the performance would change and to see if the reduced

rotational speed would reduce the heat recovery observed in the preceding test.

Ambient conditions and duration of operation of the AC system in the Test house

in its standard configuration and with the Cromer cycle for two similar pairs of days are

given in table 4-3.

Table 4-3. Ambient conditions and run times for the day pairs from the baseline set and
Cromer set No.3
Date T amb >25C T amb >28C RH TH RefH Conden
amb. duration duration sate
hours 0C hours 0C % hours hours liters
Baseline 16:00 27.96 12:30 31.99 75.31 11:21:18 13:58:21 32.2
08/06/02
Cromer 16:15 27.68 12:25 31.40 70.90 12:56:18 13:58:39 38.7
08/24/02
Baseline 12:30 27.06 5:00 30.13 76.80 7:05:15 8:20:20 22.9
08/01/02
Cromer 12:15 26.54 5:15 29.94 79.34 11:49:19 10:27:21 37.2
08/26/02__________________


Comparison of the indoor RH maintained and the AC system performance

characteristics for the two pairs of similar days are shown graphically in figures 4-10 and

4-11. The corresponding states of the air and the cooling processes are plotted on

psychrometric charts and given in figures 4-12 and 4-13









When performance of the retrofitted air handler in the Cromer set No.3 tests is

compared to the standard configuration under similar ambient conditions, the following is

observed:

* Increased dehumidification of the space -15% to 20% lower indoor RH levels are
maintained;

* 20% increase in the latent heat ratio;

* 20% decrease in the sensible cooling;

* 20% decrease in the total cooling;

* 15% decrease in the energy efficiency ratio.

During this test again unpleasant odor was introduced in the conditioned space

during the first few minutes of the AC system operation in the Cromer configuration after

longer idle periods.

4.3 Discussion

As it was mentioned earlier, the main problem with retrofitting an AC system with the

Cromer cycle equipment is the enormous increase in the pressure drop, which reduces the

air flow rate and from there many performance characteristics deteriorate. An interesting

question that was not answered in this research is how would the performance change if

the same airflow rate could be provided with the Cromer equipment in place as without it.

An attempt was made to address this question. The air intake section connected to the

Cromer unit was removed in order to allow the return air to enter the wheel directly,

some flexible duct connections were replaced with rigid ones and the sections after the

AC handler and after the wheel were extended and widened. All these changes increased

the air flow rate to about 10% below the flow rate in the standard configuration.















60

50


E7 40

30


20


70


60


50


E 40


30


20


7 9 1 3 1 2 23
me day
-o-T in Test house
-*-RH in Test house


20


70


60

50


E 40


30


20


1 3


7 9 11 13 15 17 19 2
Time of day


1 3 5 7 9 11 13 15 17 19 2
Time of day
- T in Reference house
-*- RH in Reference house


Figure 4-10. Indoor temperature and RH profiles for Baseline set and Cromer set No.3. (A) Baseline set-08/06/02. (B) Cromer set-
08/24/02. (C) Baseline set-08/01/02. (D) Cromer set-08/26/02.


7 9 1 3 7 1 2 3
me ay














32000


30000 0 0

E 28000

26000

24000 A A A A A AA

22000

20000
20 22 24 26 28 30 32 34
T amb [oC]
0.4

0.35 A

S0.3 'A--

0.25 o 8

0.2

0 .15 ....


25 28 30 33 35 38
RH in[%]


40 43 45 48

* 08/01/02 Baseline
A 08/26/02 Cromer


20 22 24 26 28 30 32 34
T amb [oC]


10000

9000

-8000

-,7000

6000

5000


25 28 30 33 35 38 40

set o 08/06/02 Baseline set
set 4 08/24/02 Cromer set


43 45 48


Figure 4-11. Comparison of performance characteristics. A) Q total vs T amb. (B) EER vs T amb. (C) LHR vs RH in.
(D) Q lat.vs RH in.


D


A A
Ao
A
tA 0
^:; '-e-0
^__ 0

















/-\ ASHRAE PSYCHROMETRIC CHART NO.1 ~-
NORMAL TEMPERATURE
BAROMETRIC PRESSURE: 101 325 kPa
Copyrghr 1992
AMERICAN SOCIETY OF IkEAT.NG -PEFRIGERATING ArND AIR.CONDITIONANG E r.CNEERS INC


SEA LEVEL


Baseline 08/06/02
Cromer 08/24/02


,~LF. .5W.
IFA...1 ~


-14


, __--. -_ -._. v .. ......


1X.
.-
_ .... ..'_ .. I.. 1 .. .


:* ..^ -' -' 2. "1 -


I I


-. ... -


-_ -.....- -..- :..-' .. -"- s -- -' ..* ...-



;- '
S4.





C44



"0 ." "o -_ 0
ENTHALPY KJ PER KILOGRAM OF DRY AIR

Figure 4-12. Psychrometric chart for similar days (Baseline set, 08/06/02 Cromer set No.3, 08/24/02)


I


.4-


I-


. ,..

















~ ASHRAE PSYCHROMETRIC CHART NO.1 /


NORMAL TEMPERATURE
BAROMETRIC PRESSURE: 101.325 kPa
Copyright 1992
AMERICAN SOCIETY OF HEATING, REFRIGERATING AND AIR-CONDITIONING ENGINEERS INC

SEA LEVEL 10
s o1 15 -

vat s.0
SENSIBLE HEAT -Qs 0 4 2
5 TOTAL HEAT Qt



g, o > '__ "'


Baseline 08/01/02
Cromer 08/26/02 ENTHALPY --
oI




...


... __ .-. "i
-- .. .- ..--.- .. -- I: -
. '- -- .. : .:-- -- ". .. % .-. . ,. .


I.

--. ,
' .. ',- -.
.'- "- .... ..... -- .y ..... . : "-- ... : -- -- '- "


"-, -- .." ':"..., ________" _" --,


".. ., ,J .,.. ; "- ,: 1 '*.*.. ,'


_T -/
/ _.; .... .. .. ... .. . ._---_ ._.. .._ __ _.. ..
- ::d .. -.'-'- -'". - ... ..: -' .. .......... -'-" :: .. .. --+: ___ d .. -._ + ... .i:L :


"" '- ." "^ -,, "' 7-- ,' ""^ _^ / '-- .... ."

^ 'W......^ '" "^ '^*- *-. /" '"''**.... :'' .. 'k.. ,. "


-I-


62--

4 4


.-.


-a0


ENTHALPY KJ PER KILOGRAM OF DRY AIR

Figure 4-13. Psychrometric chart for similar days (Baseline set, 08/01/02 Cromer set No.3, 08/26/02)


-. *', \~' s ,1 --- 'y .- -- / "- ^-..o


o


*^


/


<









A new test, called the trial test, was run. Unfortunately weather deteriorated soon

after the beginning of those test. As a result very limited data were obtained. Ambient

conditions, operational times and water removal for selected similar pairs of days from

Cromer set No.3 and the trial test are given in table 4-4. With the increased air flow in

the trial test decrease in the duration of operation and in the condensate removal is

observed. Indoor temperature and RH profiles are shown in figure 4-14. Comparison of

the calculated performance characteristics of the AC system in Cromer configuration

with different air flows is shown in figure 4-15.

Table 4-4. Ambient conditions and run times for two similar days for Cromer cycle
configuration but with different airflows
Date T amb >25C T amb >28C RH TH RefH Conden
amb. duration duration sate
hours 0C hours 0C % hours hours Liters
Cromer 11:55 30.18 5:15 30.94 67.93 9:16:21 8:45:40 28.49
08/06/02
Trialtest 12:35 28.05 7:15 29.34 71.43 8:18:19 8:13:21 27.06
08/24/02
Cromer 7:35 27.58 4:30 30.42 75.97 8:33:38 8:57:59 28.82
08/01/02
Trialtest 7:15 27.49 3:10 28.80 73.95 7:05:20 5:09:40 24.09
08/26/02 111111


The data, although quite limited to draw any general conclusions, confirmed that

the reduction in sensible cooling capacity and in the energy efficiency, observed in the

previous tests, was indeed mostly due to the reduced airflow. As it can be seen from the

trial test, with the increased airflow the Cromer cycle still was able to maintain lower RH

levels. It maintained higher LHRs that imply greater latent fraction and better

dehumidification. The increase in the airflow rate through the system, though, improved

both the total cooling and the energy efficiency. The psychrometric charts (Figures 4-16

and 4-17) show that the states of the air in the Cromer cycle are very similar regardless of






55


the air flow rate. Since, however, the sensible cooling performed by the coil increases

with the increased air flow, it is expected that the unit will 'on' for shorter periods to

satisfy the thermostat. This is expected to result in lower overall energy consumption.

The shorter run periods, however, will make the indoor RH fluctuate more compared to

the case with the lower flow rate.






























1 3 5 7 9 11 13
Time of day


15 17 19 21 23


1 3 5 7 9 11 13 15 1
Time of day


60

50

40



3 50


20



70


60
E40



C0





30


20
20


1 3 5 7 9 11 13
Time of day


15 17 19 21 23


1 3 5 7 9 11 13 15 7 1 2 2
Time of day


-o-T in Test house -)-T in Reference house
-*- RH in Test house -*- RH in Reference house

Figure 4-14. Indoor temperature and RH profiles for Cromer cycle with different flow rates. (A) Cromer set-No.3-09/03/02. (B) Trial
test-10/12/02. (C) Cromer set-No.3-08/19/02. (D) Trial test-10/13/02.


70


60


50


S40


30


20


19 21 3













35000


30000


,- 25000


200000


15000


21 23 25 27
T amb [C]


0.5

0.45

0.4
+ *< A
S0.35 AA -A

0.3 *

0.25

0.2
26 28 30 32
RH in [%]


29 31 33 35


34 36 38


21 23 25 27 29
T amb [oC]
14000

12500
... 11ooo00 ----------- A--

119500 AA


0 8000

6500 -

5000
26 28 30 32 34
RH in [%]


09/03/02 Baseline set 4 08119/02
A 10/12/02 Cromer set a 10/13/02

Figure 4-15. Comparison of performance characteristics. (A) Q total vs T amb.
(D) Q lat.vs RH in.


- Baseline set
- Cromer set

(B) EER vs T amb. (C) LHR vs RH in.


A


AA A
A A A A A A
A


B


A&A
AA A
A A 1
A A A



,o < ^ ,
+


31 33 35


36 38















--\ ASHRAE PSYCHROMETRIC CHART NO.1 H -\
NORMAL TEMPERATURE 0 IQ
BAROMETRIC PRESSURE- 101 325 kPa --.. .. -
S= ".Cop r.gl. 1992 .. .
AMERICAN SOCIETY OF HEATING, REFRIGERATING AiJD AIR CONiDITiONING E'GING"RS ING -

SEA LEVEL ---- : .. .
to



'70




Cromer 09/03/02 *










E. PE .LO- OF -R -I













ENTHALPY KJ PER KILOGRAM OF DRY AIR
Figure 4-16. Psychrometric chart for similar days (Cromer set No.3, 09/03/02 Trial test, 10/12/02)

















NORMAL TEMPERATURE 00
BAROMETRICL PRESUR 10


AME


Figure 4-17. Psychrometric chart for similar days (Cromer set No.3, 08/19/02 Trial test, 10/13/02)


Copyright 1992 -, .
RICAN SOCIETY OF iME6TIN.- RERIGERATING AND AIR CON)TDITIONI.G ENGINEERS TC ..

SEA LEVEL -..- '--




--~~- __ 4
F oo ----2 .- ---- ,- ; --~, '-"; --. ..... .









Cromer 0819/02 --..
Trial test 10/13/02 --- ---. -- ... ...







--- ----
-. .T -- "- -- -- ,- o

--- -- -- -
_o I /









ENTHAl PY- KJ PER KILOGRAM OF DRY AIR


77,















CHAPTER 5
CONCLUSIONS

The objective of the present study was to test the performance of the Cromer

cycle in field conditions. Based on what was observed in the field test conducted a few

conclusions can be drawn.

The field tests confirmed the feasibility of the Cromer cycle. In hot and humid

locations the technology enhances the dehumidification potential of the standard AC

system. The field test, however, did not confirm the predicted energy savings. In field

conditions lower indoor RH levels were achieved with a corresponding increase in the

overall energy consumption.

In summary, the field study of the Cromer cycle technology confirmed that under

one and the same thermostat setting, an AC system retrofitted with the Cromer cycle

maintains lower indoor RH levels in the space. The retrofitted system, however,

accomplishes the AC at a higher overall energy consumption.

The following additional observations were made in regard to the Cromer cycle

operation:

* Introduction of the Cromer cycle equipment increases the pressure drop in the
system thus reducing the airflow rate. Therefore when an existing AC system is
to be retrofitted with the Cromer cycle larger air handling unit has to be installed
to overcome the additional pressure drop;

* The Cromer cycle enables a conventional AC system to maintain lower indoor
humidity levels;

* The Cromer cycle increases the latent heat ratio of the AC system;









* The Cromer cycle reduces the sensible cooling performed by the cooling coil,
which results in longer run time to satisfy the thermostat setting. Therefore under
one and the same thermostat setting the Cromer cycle has a higher overall energy
requirement compared to the standard configuration;

* The air in the supply ductwork is much drier, that helps prevent fungus and
bacteria from growing in the duct linings, so the building is at lower risk from
health problems caused by such contamination;

* For a short period (2 to 3 minutes) of operation after a longer idle period, an
unpleasant odor is introduced into the space.

The equipment, at least in the configuration tested in the present study, requires

considerable additional space that not many homeowners can spare and may be willing to

dedicate.

In the tests conducted on hot days the Cromer cycle AC system maintained indoor

relative humidities around 30%. For residential houses such low humidity levels though

are neither required nor recommended. Therefore during days with high ambient

temperatures, the thermostat for the Cromer cycle AC system could be set at a higher

temperature. Because of the enhanced dehumidification abilities, even with the higher

indoor temperature the Cromer cycle would be able to maintain the indoor conditions

within the ASHRAE comfort zone. The higher thermostat setting, however, would result

in shorter operational time and reduction in the overall energy consumption.

Furthermore for applications, where maintaining low humidity levels is a must,

the technology is feasible and may be considered as a possible solution. For the same

thermostat setting the AC system in Cromer cycle configuration consumes more energy

that the conventional high-efficiency AC configuration. The Cromer cycle, however,

increases the moisture removal capabilities of the cooling coil and AC system is able to

provide and maintain much lower indoor RH levels than the standard configuration.














APPENDIX A
DATA SETS

This Appendix contains summarized information for all the data sets processed

for the purposes of the Cromer cycle field study.














Table A-I. Summary of all the data sets processed
Solar House Reference House Tamb>250C Tamb>28 C Tamb>32 C RH (25)
Date Duration AC Wheel Energy Cond. Duration Energy Duration Temp Duration Temp. Durat Temp.
Hours Wh Wh Wh Liters Hours Wh hours C hours C hours C %
BASELINE SET
17-Sep-2001 6:04:40 17730 17730 21.9 9:55:40 34000 9:50 28.24 6:15 28.74 53.28
18-Sep-2001 6:39:18 18660 18660 20.8 9:10:18 29790 8:40 26.67 4:00 28.88 71.62
19-Sep-2001 9:13:40 27020 27020 24.6 11:45:40 39790 12:00 28.62 7:10 29.05 65.59
20-Sep-2001 9:58:34 29770 29770 26.5 12:09:38 42280 14:00 28.92 8:30 30.34 64.81
21-Sep-2001 11:35:59 34110 34110 28.4 13:46:59 47010 13:35 28.12 9:10 30.85 70.25
22-Sep-2001 9:24:59 27410 27410 30.9 11:52:40 41420 9:00 30.68 8:15 31.07 63.39
CROMER SET No.1
3-Oct-2001 1:57:40 5340 80 5420 8.5 3:52:00 12380 8:30 27.39 3:25 28.46 44.01
4-Oct-2001 4:53:38 13470 190 13660 9.5 6:44:42 23710 9:20 28.35 5:50 28.93 50.06
5-Oct-2001 7:42:38 21080 360 21440 25.2 8:36:19 28530 10:10 28.79 6:55 29.85 55.09
6-Oct-2001 10:46:40 29970 430 30400 30.3 10:02:43 33500 11:35 28.28 6:35 29.42 71.10
7-Oct-2001 2:59:40 7920 140 8060 16.9 3:07:19 9680 -
8-Oct-2001 1:45:20 4850 70 4920 5.6 3:39:59 11810 5:55 25.93 59.80
10-Oct-2001 4:18:20 11640 160 11800 13.2 5:38:00 18650 7:40 26.28 1:20 28.33 62.93
11-Oct-2001 6:34:21 17670 300 17970 21 7:02:23 23410 8:55 27.89 4:20 28.66 53.13
12-Oct-2001 6:57:40 18890 320 19210 19.8 6:50:20 22910 8:40 26.06 0:17 28.15 67.29
13-Oct-2001 8:22:00 22800 300 23100 26.5 10:10:40 33410 10:10 27.71 4:35 29.14 61.01
14-Oct-2001 8:35:02 23390 370 23760 28.3 6:19:58 20650 6:25 26.03 82.31
15-Oct-2001 3:43:40 9990 170 10160 4:40:38 15170 6:20 27.22 1:15 28.28 38.36
16-Oct-2001 4:17:38 11670 180 11850 4:23:18 14260 7:25 27.04 0:40 27.80 49.30
BASELINE SET
6-Jun-2002* 8:16:20 25620 25620 21.7 9:10:40 31800 10:25 29.03 7:25 29.68 64.45
7-Jun-2002 5:53:42 17740 17740 18.3 6:25:41 21650 10:05 26.93 3:05 30.23 76.16













Table A-1. Continued
Solar House Reference House Tamb>250C Tamb>28 OC Tamb>32 C RH (25)
Date Duration AC Wheel Energy Cond. Duration Energy Duration Temp Duration Temp. Durat Temp.
Hours Wh Wh Wh Liters Hours Wh hours C hours C hours C %
8-Jun-2002 3:40:40 11060 11060 14.0 4:13:40 14190 7:05 26.79 1:40 28.29 74.51
9-Jun-2002 4:57:18 15110 15110 19.5 6:34:40 22450 11:40 27.39 5:15 28.30 66.86
10-Jun-2002 5:25:20 16600 16600 20.7 8:06:20 27480 12:30 27.82 6:15 28.52 66.05
11-Jun-2002* 3:46:58 11450 11450 13.9 4:36:01 15480 5:50 26.87 0:50 28.50 75.62
12-Jun-2002 7:07:39 22060 22060 24.9 8:52:00 30590 12:55 28.47 7:00 29.62 0:55 32.52 70.31
13-Jun-2002 8:25:40 26400 26400 26.2 11:46:00 41550 10:50 30.68 9:40 30.94 2:55 33.15 61.91
14-Jun-2002 10:02:20 31820 31820 30.5 12:36:00 44250 15:45 29.94 11:15 31.37 4:25 32.85 63.9
15-Jun-2002 9:52:00 30950 30950 25.6 11:48:20 41010 15:00 27.54 11:05 31.17 3:55 32.70 68.53
16-Jun-2002 8:00:40 24870 24870 20.7 9:29:40 33190 13:45 29.29 10:55 29.94 52.03
17-Jun-2002 2:23:40 7050 7050 9.4 2:50:00 9320 1:10 25.18 76.45
18-Jun-2002 rainy and cold 0:36:40 1970 -
19-Jun-2002* 0:44:00 2250 2250 2.5 2:55 26.94 0:40 28.53 74.31
CROMER SET No.2
19-Jun-2002* 4:20:20 12720 190 12910 17.7 3:18:39 11470 3:15 28.51 2:50 29.29 59.90
20-Jun-2002 5:20:41 15620 230 15850 23.8 5:35:22 18840 9:20 26.96 2:15 29.04 70.18
21-Jun-2002 2:14:40 6400 100 6500 11.3 2:40:19 8730 0:20 25 74.50
22-Jun-2002 0:41:00 1960 30 1990 3.9 -
23-Jun-2002 4:02:00 11910 160 12070 19.7 4:57:59 16840 9:05 26.17 2:30 28.64 80.79
24-Jun-2002 6:07:21 17920 270 18190 25.2 5:53:39 20090 9:05 28.08 6:45 28.62 67.89
25-Jun-2002 3:46:00 10850 170 11020 16.8 5:00:19 17550 5:05 27.8 2:20 28.89 71.81
26-Jun-2002 7:40:59 22370 320 22690 30.0 6:43:00 23380 10:30 27.43 3:55 28.67 72.30
27-Jun-2002 7:23:38 21560 320 21880 27.2 6:56:21 24270 11:05 27.88 6:00 29.06 71.11
28-Jun-2002 10:14:40 30080 450 30530 34.5 8:48:40 30940 11:40 29.63 8:35 30.47 1:50 32.30 74.52
29-Jun-2002 7:36:38 21980 320 22300 27.0 6:28:22 22180 6:20 29.33 4:40 30.28 80.04
30-Jun-2002 5:06:20 14800 220 15020 20.7 4:58:00 17000 6:45 27.14 2:35 29.26 87.45













Table A-1. Continued

Solar House Reference House Tamb>250C Tamb>28 OC Tamb>32 C RH (25)
Date Duration AC Wheel Energy Cond. Duration Energy Duration Temp Duration Temp. Durat Temp.
Hours Wh Wh Wh Liters hours OC hours OC hours C %
1-Jul-2002 7:06:22 20930 280 21210 29.6 8:57:01 31200 11:15 28.07 6:10 29.2 78.86
2-Jul-2002 10:05:20 29450 460 29910 35.1 7:53:20 27430 10:45 29.02 8:35 29.76 75.83
3-Jul-2002 8:05:20 23500 390 23890 28.4 7:00:40 24620 6:55 29.77 5:30 30.63 0:15 32.17 77.14
4-Jul-2002 7:00:20 20370 300 20670 25.3 6:03:40 21550 9:05 27.59 3:40 29.67 83.01
BASELINE SET _
1-Aug-2002 7:05:15 21280 21280 22.9 8:20:20 28880 12:30 27.06 5:00 30.13 76.8
2-Aug-2002 5:54:00 17780 17780 18.2 8:05:40 27460 7:30 27.14 4:45 29.74 75.81
3-Aug-2002 5:48:00 17360 17360 17.5 7:34:00 25700 7:10 28.2 4:40 29.15 69.65
4-Aug-2002 4:37:20 13710 13710 17.7 5:17:20 19770 4:55 27.52 2:15 28.66 78.81
5-Aug-2002 8:51:53 27400 27400 27.0 10:42:20 37350 15:10 29.02 9:45 30.48 0:30 32.31 70.74
6-Aug-2002 11:21:18 35850 35850 32.2 13:58:21 49310 16:00 27.96 12:30 31.99 7:00 33.54 75.31
7-Aug-2002 8:43:23 26470 26470 29.9 9:40:00 32800 20:50 26.8 4:45 28.61 79.72
8-Aug-2002 4:28:42 13540 13540 14.1 7:16:38 24660 10:50 28.48 7:50 29.18 47.54
9-Aug-2002 4:12:01 12460 12460 15.0 6:36:01 22060 6:45 26.59 3:50 28.54 65.44
10-Aug-2002 6:32:00 19960 19960 21.8 9:20:20 32070 12:05 28.9 7:55 29.44 59.13
CROMER SET No.3
12-Aug-2002 4:51:57 13930 210 14140 19.6 4:07:59 13690 3:25 26.98 1:00 28.8 77.29
13-Aug-2002 7:27:42 22220 320 22540 28.9 6:40:01 23240 8:35 28.12 5:20 29.26 68.87
14-Aug-2002 8:39:43 26670 390 27060 30.0 9:11:00 32220 10:00 27.64 7:20 30.39 76.80
15-Aug-2002 6:15:00 18810 290 19100 22.2 6:24:00 22370 5:35 29.03 4:30 29.7 72.06
16-Aug-2002 10:42:59 33260 480 33740 35.2 12:11:40 43290 15:50 28.52 9:05 29.75 1:24 32.29 73.30
17-Aug-2002 11:24:20 35190 510 35700 40.5 12:02:20 42950 11:45 27.54 8:05 30.94 2:50 32.79 78.82
18-Aug-2002 9:33:40 29130 420 29550 32.7 9:17:40 32730 7:50 29.75 6:05 30.72 0:35 32.42 66.80
19-Aug-2002 8:33:38 25180 380 25560 28.8 8:57:59 31400 7:35 27.58 4:30 30.42 0:40 32.15 75.97















Table A-1. Continued
Solar House Reference House Tamb>250C Tamb>28 OC Tamb>32 C RH (25)
Date Duration AC Wheel Energy Cond. Duration Energy Duration Temp Duration Temp. Durat Temp.
Hours Wh Wh Wh Liters Hours Wh hours C hours C hours C %
20-Aug-2002 6:02:36 17280 260 17540 21.3 4:37:40 15440 3:40 27.64 1:05 28.96 76.33
21-Aug-2002 9:25:20 27920 420 28340 29.5 10:56:57 38480 14:10 29.02 9:10 30.41 66.71
22-Aug-2002 10:19:18 30540 460 31000 30.7 11:25:59 40000 14:20 29.19 9:10 30.98 2:25 32.49 64.14
23-Aug-2002 11:42:39 34740 500 35240 33.1 10:45:00 37850 15:50 29.43 10:50 30.91 1:50 32.37 62.03
24-Aug-2002 12:56:18 38640 570 39210 38.7 13:58:39 49840 16:15 27.68 12:25 31.4 6:25 32.91 70.90
25-Aug-2002 14:32:01 43260 650 43910 42.0 13:10:21 46380 18:15 27.61 9:55 30.42 5:05 33.04 74.56
26-Aug-2002 11:49:19 34540 530 35070 37.2 10:27:21 36170 12:15 26.54 5:15 29.94 79.34
27-Aug-2002 6:38:22 19280 290 19570 25.3 6:11:01 21360 6:55 27.17 1:30 28.12 78.27
28-Aug-2002 8:24:39 24440 400 24840 27.7 10:09:23 35050 9:20 27.96 5:50 28.86 73.60
29-Aug-2002 6:37:59 19210 310 19520 22.6 7:32:01 25340 8:05 28.08 5:10 28.92 71.55
30-Aug-2002 4:35:21 13120 210 13330 16.7 4:12:38 14100 4:45 27.25 1:30 29.06 78.49
31-Aug-2002 6:03:42 17670 270 17940 22.0 6:02:19 20460 10:10 26.9 0:40 28.19 78.02
1-Sep-2002 8:56:18 26390 420 26810 29.6 8:51:40 31180 13:05 28.43 5:50 30.41 73.56
2-Sep-2002 10:07:22 29720 430 30150 31.4 9:32:59 33220 15:00 28.31 7:35 29.99 71.51
3-Sep-2002 9:16:21 27090 420 27510 28.5 8:45:40 30300 11:55 30.18 5:15 30.94 67.93
TRIAL TEST _
11-Oct-2002* 8:48:18 27040 380 27420 32.2 8:32:00 29090 10:20 29.23 7:30 30.25 62.71
12-Oct-2002 8:18:19 25010 380 25390 27.1 8:13:21 28740 12:35 28.05 7:15 29.34 71.43
13-Oct-2002 7:05:20 21290 300 21590 24.1 5:09:40 18260 7:15 27.49 3:10 28.8 73.95
14-Oct-2002 5:15:22 15840 230 16070 19.7 5:43:20 20530 6:55 28.11 4:30 29.06 67.52














APPENDIX B
UNCERTAINTY ANALYSIS

This appendix presents the uncertainty analysis carried out to evaluate the

uncertainty of the experimental measurements as well as of the quantities calculated

using these measured variables.

Devices used to measure the relative humidity, temperature, air velocity, etc. have

certain accuracy that impacts the uncertainty of the corresponding experimentally

measured quantities. Table B- presents the uncertainty of the experimental

measurements.

Table B-1. Uncertainty of experimental measurements
Quantity Instrument Uncertainty
Relative humidity THMD60U/YO + 2%
Temperature HMD60U/YO 0.3 C
Air velocity Hot Wire Anemometer + 3% reading
Circumference Ruler + 0.5 cm
Watt-hours Transducer Model WL40R-052 + 0.5% F.S.

The uncertainty analysis of the calculated values, that use experimentally

measured quantities, was done following the method, described by Coleman [1999].

Briefly the method involves the following procedure: Let certain experimental result R, is

a function of N number of measured variables X,:

R= R(X,,X2,X3,..... ,X ) (B-l)

Then the uncertainty in the result is given by

22 R 2 2
U = U + U +...+ U (B-2)
U XR )xl OX2 X2 Ox"








where the Ux, are the uncertainties in the measured variables X,.

By dividing each term in the equation by R2 and by multiplying each term on the

right-hand side by (X, /X,), we obtain the uncertainty equation in a nondimensionalised

form:

(UR R2 X, a2 R x x X_ R _, X" R x
R ) = R a x 2 2 2 2 (B-3)

where UR /R is the relative uncertainty of the result. The factors Ux I/X, are the relative

uncertainties for each variable.

The factors in the parenthesis that multiply the relative uncertainties of the

variables are called uncertainty magnification factors (UMFs). They indicate the

influence of the uncertainty of the corresponding variable on the uncertainty in the result.

If a UMF is greater than 1 this indicates that the uncertainty in the variable is magnified

as it propagates through the data reduction equation into the result. If UMF value is less

than 1 then the uncertainty in the variable is diminished as it propagates through the data

reduction equation into the result.

For instance, this method applied to our study to determine the uncertainty in the

Latent cooling Qa = m(h, h4 ) gives the following:


2 + O h4 + (B-4)




The partial derivatives of Qiat in respect to the three variables, used for its calculation:

Ol m and (h, h ) (B-5)
Sh h' Sh. 4n 44
1 4








By substituting in the equation and nondimensionalising we obtain

oUQI' 2 = h 1 2 Uhl 42 hn4'- 2 gh 4 2 q- )2 (B-6)

Qla h,-h,- 4 h, h-h [, ) 4. h4'

All the calculated quantities, the functions of those quantities, the partial

derivatives of these functions with respect to the variables they depend on and the

corresponding non-dimensional form of the uncertainty equation, are listed in table B-4.

In the current study uncertainties of the quantities calculated have been

determined by picking several days in each set of data, averaging the daily values for

each day, finding the corresponding uncertainty and after that finding the average

uncertainty for each data set. This process is illustrated in table B-2.

The higher uncertainties observed in respect to Q lat and LHR are as a result of

the comparatively small moisture removal. As it can be seen from the corresponding

uncertainty equations, this small moisture removal makes the denominator (hl-h4') small

and consequently the UMFs are high. Therefore in theses cases the uncertainties of the

measured quantities magnifies as they propagate through the data reduction equations

into the final results for Q lat and LHR.










Table B-2. Average uncertainty
Date U latent U sens ULHR U total U EER Uhl Uh4 U h4'
% % % % % % % %
No wheel
6 June, 2002 31.16 7.49 29.26 6.23 6.25 2.30 2.17 2.74
8 June, 2002 25.91 10.68 22.32 7.88 7.90 2.20 2.07 2.73
9 June, 2002 24.76 11.38 21.14 8.10 8.11 2.17 2.05 2.68
12 June, 2002 26.23 8.44 24.17 6.58 6.60 2.25 2.09 2.66
14 June, 2002 29.35 8.05 27.42 6.47 6.48 2.27 2.11 2.80
16 June, 2002 33.07 9.84 28.58 8.09 8.11 2.32 2.13 2.73
AVERAGE 28.41 9.31 25.48 7.23 7.24 2.25 2.10 2.72
Wheel (42 rpm)
27 June, 2002 21.12 11.63 18.24 7.59 7.60 2.56 2.60 4.21
28 June, 2002 23.89 11.28 20.97 7.68 7.70 2.57 2.67 4.60
3 July, 2002 22.52 11.19 24.55 7.45 7.46 2.56 2.66 4.67
AVERAGE 22.51 11.37 21.25 7.57 7.59 2.56 2.64 4.49
Wheel (11 rpm)
13 Aug., 2002 19.23 8.28 16.93 6.13 6.15 2.23 2.55 3.86
28 Aug., 2002 24.22 8.30 21.36 6.59 6.61 2.54 2.67 3.81
30 Aug., 2002 22.16 8.70 19.64 6.53 6.55 2.45 2.60 4.23
31 Aug., 2002 20.53 8.73 17.79 6.53 6.55 2.44 2.58 3.76
1 Sep., 2002 24.76 8.39 22.01 6.62 6.64 2.53 2.64 4.02
2 Sep., 2002 25.46 8.27 22.51 6.66 6.68 2.57 2.69 3.74
3 Sep., 2002 23.89 7.26 21.98 5.83 5.85 2.03 2.69 3.92
AVERAGE 22.89 8.28 20.32 6.41 6.43 2.40 2.63 3.91

Table B- 3. Uncertainty of calculated values
Quantity No wheel Wheel (42 rpm) Wheel (11 rpm)

1. Enthalpy Point 1: 2.25 % Point 1: 2.56 % Point 1: 2.40 %

Point 4: 2.10 % Point 4: 2.64 % Point 4: 2.63 %
Point 4': 2.72 % Point 4': 4.49 % Point 4': 3.91 %
2. Mass flow rate 3.1% + 3.1% 3.1%
3. Sensible cooling + 9.31% 11.37 % 8.28 %

4. Latent cooling + 28.4 % 22.51% 22.89 %
5. Total cooling + 7.23 % 7.57 % 6.41 %
6. LHR +25.48% 21.25 % 20.32 %
7. EER + 7.2% + 7.59% + 6.43 %










Table B-4. Calculated values
Quantity Function Partial derivatives Uncertainty equation
Latent cooling Q1Q m( L) m UQ 2 ( 2U 2+ h4'2Uh42 + (U 2
. .. .h( 4) t ; U T h Uh h4 h4. Uf
ihi h h
laQat h_ -
m

Sensible Q U 2 2 2 2 2 2
cooling Qsens Q~sens h h4 h 4 h4 Uh4 + h4 h4 +
C h44 h4 h4- h4 h4 h4 m



Total cooling 2m(h h4) )tota -- U 2 h 2 2 I 2 2 2 2
Qt&tal 0. Q total hi h4 hi h -hlh4) h4 m
h/14
Total (h, -h4)
Om










Table B-4. Continued
Latent heat ratio hi -h4i Rat h4- h4 U 2 h h (h4 h ) ( Uh
-Rt R hla-,h1 4 1hl (h -h4)2 R (hi- h4) h- h4.) h h )
Rt -1 22 2
aO, (i h4) h4 N,4 + h4 \r h4 h,
OR^ath4hi hih4'J h 4' hi hJ4 h 4
Sensibleheati-)2h -h________h4Rh4-h4UR 2= h4h -_ h) (hi 2hh 4)2
Sensible heat (h -h h 2 2 2
sens h -h4 Oh, (h -h4)2 R s (h4- h4 Xh h4) h4
ORsens I h 2 U 2 22 h _2
Oh4, (hl -h4) h4 Uh4 + h Uh
R e_ h4 -hl h- h4 h 4 h h4 h1
C/14 (h, h4 )2
Energy EER SEER -1 UE2 o 2 2
efficiency ratio m tEER-otl oWm R

9EER Qt0t
8W W 2
















APPENDIX C
FORTRAN 77 PROGRAM
FOR CALCULATION OF PERFORMANCE CHARACTERISTICS OF THE
COOLING CYCLE

The following program was written to calculate the parameters used to evaluate

the performance of the cooling cycle. These parameters are Qtotal, Qlat, Qsens, LHR,

SHR and apparent energy efficiency ratio. The program also obtains such

thermophysical properties of the moist air as enthalpy and humidity ratio. To accomplish

the latter the program uses a link to the software package PROPATHI (PROgram

PAckage for THermophysical properties of fluids).



PROGRAM CROMER.FOR
C *****************************************************************
C THIS PROGRAM CALCULATES THE FOLLOWING PERFORMANCE *
C CHARACTERISTICS: *
C LATENT AND SENSIBLE COOLING *
C LATENT HEAT RATIO AND SENSIBLE HEAT RATIO *
C *TOTAL COOLING PERFORMED BY AN AC HANDLER *
C *APPARENT ENERGY EFFICIENCY RATIO *
C AND BASED ON TEMPERATURE AND RELATIVE HUMIDITIES *
C *FINDS ENTHALPY AND ABSOLUTE HUMIDITY *
C ****************************************************************
C
C
C DECLARATIONS OF TABLE COLUMNS
REAL TEMPO(25), ENTH(25,10),HUMR(25,10),TIME(25),HDIF(25)
C DECLARATION OF THE MAIN ARRAYS
REAL INPUT (25,13),RESULT (25,9),PROPERTY(25,11), POWER (25)
INTEGER AIRFLOW
C IROW NUMBER OF ROWS
C 13 NUMBER OF COLUMNS (12 FOR AC WITH NO WHEEL)
CHARACTER* 10 FILESOURCE, FILERESULT, PROPERTIES,
1 ENTEXT, HRTEXT
C
C
C INFORMATION REQUIRED FOR THE LINK TO THE PROPERTY PROGRAM
C
COMMON/UNIT/ KPA, MESS







74


KPA=I1
MESS=1
P=1.01325
C
C DATA INPUT COMMUNICATION WITH THE USER
C
ENTEXT=' H'
HRTEXT=' W'
PRINT*, 'ENTER THE NAME OF THE SOURCE FILE + EXTENSION'
READ*, FILESOURCE
PRINT*, 'ENTER A NAME FOR THE RESULT FILE +EXTENSION'
READ*, FILERESULT
PRINT*,'PLEASE ENTER THE AIR FLOW [kg/h]'
READ*, AIRFLOW
PRINT*,'PLEASE ENTER NUMBER OF ROWS'
READ*, IROW
C
C DATA INPUT PROGRAM READS FROM THE USER'S FILE
C
OPEN (20, file=FILESOURCE,ACCESS='DIRECT',
1 FORM='FORMATTED',RECL=120)
DO 10 Il=1,IROW
READ(20, FMT=100) (TEMPO(I2), I2=1,10),TIME(I1),POWER(I1)
DO 11 13=1,10
INPUT(I1,I3)=TEMPO(I3)
11 CONTINUE
INPUT(I1,I3)=TIME(I1)
INPUT(I1,I3+1)=POWER(I1)
10 CONTINUE
100 FORMAT (IX, 10(F6.2), F6.4, 1X,F7.1)
CLOSE(20)
C
C LINK TO PROPATH PROPERTY PROGRAM FOR DETERMINATION OF
C ENTHALPY AND ABSOLUTE HUMIDITY
C
DO 13 Il=1,IROW
DO 14 13=1,9,2
ENTH(I1,I3)=HC(P,INPUT(I1,I3),(INPUT(I1,(I3+1)))/100)
HUMR(I1,I3)=XC(P,INPUT(I1,I3),(INPUT(I1,(I3+1)))/100)
PROPERTY(I1,I3)= ENTH(I1,I3)*0.001
PROPERTY(I1,I3+1) = HUMR(I1,I3)*1000
14 CONTINUE
13 CONTINUE
C
C CALCULATION OF POINT H4prime=f(Wsup,Tret)
C
C Wsup = PROPERTY(I1,10), Tret = INPUT(I1,3)
DO 15 Il=1,IROW
TEMPO(I1)=HD(P,INPUT(I1,3),(PROPERTY(I1,10)*0.001))
PROPERTY(I1,11)=TEMPO(I1)*0.001
PRINT*,'H4PR=',PROPERTY(I1,11)
15 CONTINUE
C
C
C CALCULATION OF SHR, LHR, COOLING CAPACITY AND EER
C










C CALCULATION OF SENSIBLE HEAT RATIO (SHR)
C AND LATENT HEAT RATIO (LHR)
C
DO 17 I1=1,IROW
HDIF(I11)=PROPERTY(I1,3)-PROPERTY(11,9)
RESULT(I1,1)=(PROPERTY(I1,11)-PROPERTY(I1,9))/HDIF(I1)
RESULT(I1,2)=(PROPERTY(I1,3)-PROPERTY(I11,11))/HDIF(I1)
17 CONTINUE
C
C CALCULATION OF TOTAL COOLING CAPACITY
C Q total = (hl-h4) x (mass flow rate)
C
DO 18 Il= 1,IROW
RESULT(I1,3)=AIRFLOW
RESULT(I1,4)=HDIF(I1)*AIRFLOW
RESULT(I1,5)=RESULT(I1,4)*0.94782
PRINT*,'COOLING=', RESULT(I1,4)
18 CONTINUE
C
C CALCULATION OF EER = (TOTAL COOLING)/(POWER INPUT)
C
DO 19 Il=1, IROW
RESULT(I1,6)=INPUT(I1,12)
RESULT(I1,7)=RESULT(I1,5)*INPUT(I1,11)/RESULT(I1,6)
19 CONTINUE
C
C CALCULATION OF SENSIBLE AND LATENT COOLING
C
DO 22 I1= 1,IROW
RESULT(I1,8)=(PROPERTY(I1,11)-PROPERTY(I1,9))*RESULT(I1,3)
RESULT(I1,9)=(PROPERTY(I1,3)-PROPERTY(I1,11))*RESULT(I1,3)
22 CONTINUE
C
C RESULTS RECORDED IN A FILE
C
OPEN (21, file=FILERESULT)
WRITE(21, FMT=107)
WRITE(21, FMT=108) 'DATE IS:', FILESOURCE
WRITE(21, FMT=107)
WRITE(21, FMT=106) 'Tth','RHth','Tret','RHret','Tbef,'RHbef,
1 'Taft','RHaft','Tsup','RHsup',' Time'
WRITE(21, FMT=106) 'oC ',' % ',' oC',' % ',' oC ',' % ',
1 oC ',' % ',' oC ',' oC',' %','hours'
DO 20 I1=1, IROW
WRITE(21, FMT=103) II,(INPUT(I1,I3), I3=1,10),INPUT(I1,11)
20 CONTINUE
WRITE(21,101) (ENTEXT,I1,HRTEXT,I1, I1=1,5), Entext,'Pr'
DO 16 Il=1,IROW
WRITE(21, FMT=102),I1, (PROPERTY(I1,I3), 13=1,11)
16 CONTINUE
101 FORMAT (/5(5X, A2, I1, 5X, A2,Il1),6x, A2,a3)
102 FORMAT (I2,1X,5(F8.3, F8.3),1X,F8.3)
WRITE(21, FMT=107)
WRITE(21, FMT=104) 'SHR','LHR','FLOW','COOLING','COOLING',
1 'POWER','EER','SENS COOL','LAT COOL'
WRITE(21, FMT=104)' -','- ','kg/h',' kJ/h ',' Btu/h',







76


1 Wh ',' ','kJ/h','kJ/h'
DO 21 I1=1,IROW
WRITE(21, FMT=105) II,(RESULT(I1,I3),I3=1,9)
21 CONTINUE
C
C
103 FORMAT (IX, 12, 10(F8.2), 1X,F8.4)
104 FORMAT (5X,A4, 2X,A4, 1X,A6, 2(2X,A8), 4X,A5, 2X,A4,
1 3X,A9, 3X,A9)
105 FORMAT (I2,1X,2(1X,F5.2), 2X,F6.0, 2(F10.2), 2X,F6.0,
1 2X,F5.2, 1X,F10.2, 2X,F10.2)
106 FORMAT (5X,A5, 4X,A5, 3X,A5, 2X,A6, 2X,A5, 2X,A7, 4(1X,A7),
1 3X,A6)
107 FORMAT (//)
108 FORMAT (2(2X,A10))
CLOSE(21)

END














APPENDIX D
LATENT COOLING TRENDLINES










14000

12500

11000

9500

8000

6500


28 31 34 37 40 43 46 49 52
RH in [%] Standard config.
A Cromer cycle


26 29 32 35 38 41 44 47 50
RH in [%]


Cromer cycle Standard configuration
y = 284.59x+ 649.4 y = 474.01x 11711


0.9693


R2= 0.9051


Cromer cycle
y =273.6x + 2770.5

R2= 0.7958


Standard configuration
y = 585.47x 17076

R2 0.8916


Configuration
Indoor RH Cromer Standard Increase
[%] Q lat Q lat [%]
30 9187.1 2509.3 266.12
35 10610.1 4879.4 117.45
40 12033.0 7249.4 66.99
45 13456.0 9619.5 39.88
50 14878.9 11989.5 24.10


,o rinTi, vi' -rll r,
Indoor RH 'romrner tl.-r, dard Increr e
[%] Q lat Q lat [%]
30 10978.5 488.1 2149.23
35 12346.5 3415.5 261.49
45 15082.5 9270.2 62.70
50 16450.5 12197.5 34.87


Figure D-1. Latent cooling vs. RH in. (A) Baseline 06/07/02, 06/09/02; Cromer 06/26/02, 06/27/02. (B) Baseline 06/10/02, 06/13/02;
Cromer 06/26/02, 06/27/02. (C) Baseline 08/01/02, 08/06/02; Cromer 08/24/02, 08/26/02. (D) Baseline 08/02/02, 08/05/02; Cromer
08/16/02, 08/19/02. (E) Baseline 08/03/02, 08/06/02; Cromer 08/19/02, 08/24/02. (F) Cromer set No.3-08/19/02, 09/03/02; Trial test-
10/12/02, 10/13/02.


14000


12500

11000

- 9500

8000

6500


B


A *





S
0*













10000


9000

8000 A.__ t

7000

6000

5000
25 30 35 40 45 50


RH in [%]


11000

10000

9000

8000


7000 -

6000
28 31 34 37 40 43 46 49
RH in [%]


Cromer configuration
y = 348.61x-2615.7

R2 = 0.6453


Standard confi Standard configuration er configuration
y = 403.52x ,rr cl !33.23x 2238


R = 0.7144


R = 0.942


Standard configuration
y =466.38x- 12367
R2 = 0.7493


Config duration
Indoor RH Cromer Standard Increase
[%] Q lat Q lat [%]
26 6099.6 283.5 2051.52
30 7842.6 2301.1 240.82
40 11328.7 6336.3 78.79
45 13071.8 8353.9 56.47


Configuration __
Indoor RH Cromer Standard Increase
[%] Q lat Q lat [%]
30 7758.9 1624.4 377.65
35 9426.1 3956.3 138.23
40 11091.2 6288.2 76.38
45 12757.4 8620.1 48.00
50 14423.5 10952.0 31.70


Figure D-1. Continued













10500


9500

8500 /

7500

6500 A
A*
5500 I
25 28 31 34 37 40 43 46 49


RH in [%]


12500

11000

9500

8000


6500 f-

5000 -
24 26 28 30 32 34 36 38


* Standard config.
A Cromer cycle


RH in [%]


Cromer cycle
326.13x- 2114.9
R2= 0.8813


Standard configuration
y = 505.12x- 14006
R2= 0.6948


Cromer test No. 3
y =358.45x-3025
R2 = 0.9234


Trial test
y 335.63x-358.81
R2= 0.4256


,'ji iti Liurr I CI
rind':or: RH I. rio i i ialnd rd Iii': I- -e
[%] Q lat Q lat [%]
26 6038.4 -
30 7669.0 1147.6 568.26
35 9299.7 3673.2 153.18
40 10930.3 6198.8 76.33
45 12561.0 8724.4 43.98


Configuration
Indoor RH Cromer Standard Increase
[%] Q lat Q lat [%]
28 7011.6 9038.8 28.91
30 7728.5 9710.1 25.64
32 8445.4 10381.4 22.92
34 9162.3 11062.6 20.63


Figure D-1. Continued














LIST OF REFERENCES


American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
(ASHRAE). (1996). ASHRAE Handbook of HVAC Systems and Design, Atlanta,
Georgia.

American Society of Heating, Refrigerating and Air-Conditioning Engineers, Inc.
(ASHRAE). (1997). ASHRAE Handbook of Fundamentals, Atlanta, Georgia.

Chant E. and Jeter S. (1994). A Steady-state simulation of an advanced desiccant-
enhanced cooling and dehumidification system. ASHRAE Transactions, v.100, pt.2,
339-347.

Coleman H. and Glenn S. (1999). Experimentation and Uncertainty Analysis for
Engineers, 2nd edition, Wiley Inter-science, New York.

Cromer C. (1988). United States patent, Patent Number 4719761, Date of Patent,
January 19, 1988.

Cromer C. (1997). Cromer cycle: An energy efficient solution to indoor air quality
problems. Engineering Solutions to Indoor Air Quality Problems, July 1997, Research
Triangle Park, NC.

Dolan W. (1989). Desiccant cooling systems a new HVAC opportunity. Energy
Engineering, v.86, n.4, 6-9.

Energy Information Administration (EIA). 2000. Available from URL:
http://www.eia.doe.gov/emeu/consumptionbriefs/recs/actrends/recs ac trends.html. Site
last visited September 2002

Jones W. (2001). Air Conditioning Engineering. 5th edition, Oxford Press, Boston.

Hands Down Software Group, "ASHRAE Psychrometric Chart", ASHRAE, 1992.

Kosar D., Witte M., Shirey D. and Hedrick R. (1998). Dehumidification issues of
standard 62-1989, AHRAE Journal, 71-75.

Lizardos E. (1993). Designing HVAC systems for optimum indoor air quality. Energy
Engineering Journal of the Association of Energy, v.90, n.4, 6-29.

Mago P. and Goswami Y. (2001). A study of the performance of a hybrid liquid
desiccant cooling system using lithium chloride. Proceedings of the International Solar
Energy Conference, ASME, April 2001, 133-139.









Nimmo B., Collier R. and Rengarajan K. (1993). DEAC: Desiccant enhancement of
cooling-based dehumidification. ASHRAE Transactions: Symposia of the 1993
ASHRAE Winter Meeting, v.99, pt.1, 842-848.

Oberg V. (1998). Heat and Mass Transfer Study of a Packed Bed Absorber/Regenerator
for Solar Desiccant Cooling. Doctoral Dissertation, University of Florida, Gainesville.

Pesaran A., Penney T. and Czanderna A. (1992). Desiccant cooling: state-of-the-art
assessment. National Renewable Laboratory, Golden, Colorado, NREL Report No.
NREL/TP-254-4147.

PROPATH Group. (2001). PROPATH: A Program Package for Thermophysical
Properties of Fluids, version 12.1.

Rengarajan K. and Nimmo B. (1993). Desiccant enhanced air conditioning (DAEC). An
approach to improved comfort. Heat Pump and refrigeration Systems Design, Analysis
and Applications, AES, v.29, 129-138.

Zhang L. and Niu J. (2002). Performance comparisons of desiccant wheels for air
dehumidification and enthalpy recovery. Applied Thermal Engineering, v.22, n. 12,
1347-1367.

Zheng W.and Worek W. (1993). Numerical simulation of combined heat and mass
transfer processes in a rotary dehumidifier. Numerical Heat Transfer: An Int. Journal of
Computation and Methodology, part A, v.23, n.2, 211-232.

Zheng W., Worek W. and Novosel D. (1995a). Effect of operating conditions on
optimal performance of rotary dehumidifiers. Journal of Energy Resources Technology,
Transactions of ASME, v. 117, n. 1, 62-66.

Zheng W., Worek W. and Novosel D. (1995b). Performance optimization of rotary
dehumidifiers. Journal of Solar Energy Engineering, Transactions of the ASME, v. 117,
n.1, 40-44.














BIOGRAPHICAL SKETCH

Bronislava Veltcheva was born in Sofia, Bulgaria. To pursue a career in

Engineering she was inspired by her father. He was not only one of the best experts in

the thermal science field in Bulgaria. His love, devotion and enthusiasm encouraged

Bronislava to find her way in engineering. Bronislava began her engineering studies at

the Technical University of Sofia, where she obtained her B.S. degree in mechanical

engineering. After spending a few years working for an engineering company in Sofia,

she was invited by her cousin Ani to visit Gainesville, Florida. During her stay there,

simply from curiosity, Bronislava started going to classes. Very soon, however, she was

thrilled by the excellent research opportunities at the University of Florida. A year later

Bronislava returned to Florida (this time as a graduate student in the College of

Engineering). During her studies at the University of Florida, Bronislava was

accompanied by her husband Ivan and her two wonderful little daughters (Valli and Toni)

whose love and support were priceless for her.