Citation
Bubble Sliding Heat Transfer Enhancement in Forced Convective Flow

Material Information

Title:
Bubble Sliding Heat Transfer Enhancement in Forced Convective Flow Liquid Crystal Thermography and Computational Study
Creator:
Venuvanalingam, Prasanna Kumar
Place of Publication:
[Gainesville, Fla.]
Florida
Publisher:
University of Florida
Publication Date:
Language:
english
Physical Description:
1 online resource (114 p.)

Thesis/Dissertation Information

Degree:
Doctorate ( Ph.D.)
Degree Grantor:
University of Florida
Degree Disciplines:
Mechanical Engineering
Mechanical and Aerospace Engineering
Committee Chair:
KLAUSNER,JAMES F
Committee Co-Chair:
MEI,RENWEI
Committee Members:
HAHN,DAVID WORTHINGTON
CURTIS,JENNIFER S
Graduation Date:
8/9/2014

Subjects

Subjects / Keywords:
Boiling ( jstor )
Bubbles ( jstor )
Calibration ( jstor )
Heat transfer ( jstor )
Heaters ( jstor )
Liquid crystals ( jstor )
Simulations ( jstor )
Sliding ( jstor )
Temperature profiles ( jstor )
Velocity ( jstor )
Mechanical and Aerospace Engineering -- Dissertations, Academic -- UF
boiling -- bubble -- computational -- enchancement -- flowboiling -- forcedconvection -- hfe7000 -- liquidcrystal -- numerical -- sliding -- starccm -- stationary -- thermography -- turbulentflow -- v2fmodel
Genre:
bibliography ( marcgt )
theses ( marcgt )
government publication (state, provincial, terriorial, dependent) ( marcgt )
born-digital ( sobekcm )
Electronic Thesis or Dissertation
Mechanical Engineering thesis, Ph.D.

Notes

Abstract:
In this work the mechanism of the heat transfer enhancement due to the introduction of bubbles sliding along the wall in an internal forced convective flow is studied both experimentally and computationally. In order to study the bubble sliding process, liquid crystal thermography is employed to measure the temperature field on the heater surface in an area following the injection of the bubbles. A novel test section is designed and fabricated to meet the multitude of requirements of liquid crystal thermography and high speed imaging. New liquid crystal thermography calibration techniques are designed and implemented to reduce the uncertainty in temperature measurements with a better resolution. A new image processing code is developed in MATLAB to process the bubble motion and provide statistics of the mean diameters, position and velocity. A computational study on the heat transfer enhancement is conducted using a commercial CFD code in order to mitigate the experimental constraints which does not allow for a parametric variation of relative velocity or bubble size with the present facility. The key parameters for the computational investigation are bubble relative velocity, bubble size, bubble shape, and the micro layer thickness between the bubble and the heater surface. For bubbles sliding along the heater wall, the computed heat transfer enhancement in terms of temperature drop is only a fraction of what is measured in the experiments. The heat transfer enhancement due to sliding bubbles is insensitive to micro-layer thickness and marginally sensitive to bubble shape. Turbulent channel flow over a stationary bubble to be released from the injection needle is simulated. The computed temperature drop agrees reasonably well with the measured data. The stationary truncated spherical bubble also showed no appreciable change in the peak temperature drop, but the wake width increased slightly due to the increase in the bubble radius in order to maintain the constant cross-sectional area. The dominant heat transfer mechanism responsible for the heat transfer enhancement typically attributed to bubble sliding has been identified to be the disruption caused by the stationary bubble located at the nucleation site or the injection needle in this case. ( en )
General Note:
In the series University of Florida Digital Collections.
General Note:
Includes vita.
Bibliography:
Includes bibliographical references.
Source of Description:
Description based on online resource; title from PDF title page.
Source of Description:
This bibliographic record is available under the Creative Commons CC0 public domain dedication. The University of Florida Libraries, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.
Thesis:
Thesis (Ph.D.)--University of Florida, 2014.
Local:
Adviser: KLAUSNER,JAMES F.
Local:
Co-adviser: MEI,RENWEI.
Electronic Access:
RESTRICTED TO UF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE UNTIL 2015-08-31
Statement of Responsibility:
by Prasanna Kumar Venuvanalingam.

Record Information

Source Institution:
UFRGP
Rights Management:
Applicable rights reserved.
Embargo Date:
8/31/2015
Classification:
LD1780 2014 ( lcc )

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Full Text

PAGE 23

0.00 0.50 1.00 1.50 2.00 2.50 0.10 1.00 10.00 Liquid velocity (m/s) Kenning and Kao Thorncroft

PAGE 64

0 1 2 3 4 5 6 7 0 50 100 150 200 250 300 Turbulent KE / U 2 Y + Re = 13750 Kim et al (1987) Re = 18316 Current Simulation

PAGE 75

38.5 39 39.5 40 40.5 41 41.5 42 -5 -3 -1 1 3 5 Temperature ( C ) Z (mm) Experimental Data Micro-layer thickness 50mu Micro-layer thickness 75mu Micro-layer thickness 100mu

PAGE 76

38.5 39 39.5 40 40.5 41 41.5 42 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature ( C ) Z (mm) Experimental Data Full Sphere 25 % Truncation 50 % Truncation

PAGE 78

38.5 39 39.5 40 40.5 41 41.5 42 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature ( C ) Z (mm) Experimental Data Inline Hemisphere Laterally Separated Hemisphere

PAGE 84

0 0.05 0.1 0.15 0.2 0.25 0.3 0.35 0.4 -1 0 1 2 3 4 5 6 7 8 9 10 U (m/s) Y (mm) Flow over the Bubble Channel Flow -1 1 3 5 7 9 37 38 39 40 41 Y (mm) Temperature ( C ) Flow over the Bubble Channel Flow

PAGE 86

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble

PAGE 87

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble 38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble

PAGE 88

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble 38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble

PAGE 91

0 0.05 0.1 0.15 0.2 0.25 0.3 -2 0 2 4 6 8 10 Velocity (m/s) Y (mm) Through the Bubble Channel Flow

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-1 0 1 2 3 4 5 6 7 8 9 10 36 38 40 42 Y (mm) Temperature ( C ) Flow over a Bubble Channel Flow

PAGE 94

38 38.5 39 39.5 40 40.5 41 41.5 42 -5 -3 -1 1 3 5 Z (mm) Expt Simulation Stationary Bubble

PAGE 95

38 38.5 39 39.5 40 40.5 41 41.5 42 -5 -4 -3 -2 -1 0 1 2 3 4 5 Z (mm) Expt Simulation Stationary Bubble

PAGE 96

38 38.5 39 39.5 40 40.5 41 41.5 -5 -4 -3 -2 -1 0 1 2 3 4 5 Z (mm) Expt Simulation Stationary Bubble 38 38.5 39 39.5 40 40.5 41 41.5 42 -5 -4 -3 -2 -1 0 1 2 3 4 5 Z (mm) Expt Simulation Stationary Bubble

PAGE 97

38.5 39 39.5 40 40.5 41 41.5 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble

PAGE 99

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Microlayer-50mu Simulation Microlayer-75mu

PAGE 100

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Stream Wise Position X= 4mm Expt Simulation Microlayer-50mu Simulation Microlayer-75mu

PAGE 101

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation -Full sphere Simulation-Truncated Sphere 38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation -Full sphere Simulation-Truncated Sphere

PAGE 102

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Full sphere Simulation -Truncated Sphere 38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Full sphere Simulation -Truncated Sphere

PAGE 103

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Full sphere Simulation -Truncated Sphere

PAGE 104

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble Simulation Two stationary Bubbles

PAGE 105

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble Simulation Two Stationary Bubbles

PAGE 106

38 38.5 39 39.5 40 40.5 41 -5 -4 -3 -2 -1 0 1 2 3 4 5 Temperature (C) Z (mm) Expt Simulation Stationary Bubble Simulation Two Stationary Bubbles