Selected Projects
On this page you will find example research activities summarized in poster form in a pdf file. When you view the file, the entire poster can be seen at approximately 100% magnification. To read the individual panels, images, and graphs, etc, try 400% magnification and work your way across the poster. Below each poster file link is a listing of the publications associated with each project.
Single-Phase and Two-Phase Flows in Mini-Channels
Introduction
This work began in the mid-1990's and addresses the issue of convection in channels with hydraulic diameters near 1 millimeter. The work uses liquid crystal thermography to image the surface temperature field on one wide wall of a rectangular channel with channel spacing varied between 2.0 mm and 0.5 mm. While results for single-phase and nucleate flow boiling have been reported in the literature, the focus of the work as tended to be on boiling incipience.
Support
Texas Advanced Technology Program
National Science Foundation
Publications
Y. Chin, An Experimental Study of Flow Boiling in a Narrow Channel: From Convection to Nucleate Boiling, Ph.D. Dissertation, December, 1997.
M. S. Lakshminarasimhan, Boiling Incipience in Thin Channels, M.S. Thesis, August, 1999.
Q. Lu, Single and Two-Phase Heat Transfer in A Micro-channel, M.S. Thesis, August, 2001.
E. Daniel, Transition From Boiling Onset to Fully Developed Nucleate Boiling in a Narrow Channel, M.S. Thesis, May, 2006.
"An Experimental Investigation of Flow Boiling Incipience in a Narrow Rectangular Channel Using Thermochromic Liquid Crystals," Y. Chin, L. C. Witte & D. K. Hollingsworth, Proceedings of the 7th AIAA/ASME Joint Thermophysics Conf., 1998.
"A Study of Convection in a Asymmetrically Heated Duct Using Liquid Crystal Thermography," Y. Chin, D. K. Hollingsworth & L. C. Witte, Vol. 2., pp. 63-70, Proceedings of the 7th AIAA/ASME Joint Thermophysics Conf., 1998.
"Boiling Incipience in Narrow Channels," M. S. Lakshminarasimhan, Y. Chin, D. K. Hollingsworth & L. C. Witte, Proceeding of the Int. Mech. Engg. Congress and Exposition, Orlando, Florida, November, 2000.
"Convective Heat Transfer In Vertical Asymmetrically Heated Narrow Channels," Y. Chin, M. Lakshminarasimhan, Q. Lu, D. K. Hollingsworth, & L. C. Witte, ASME J. Heat Transfer, December, 2002, Vol. 124, 1019-1025.
"Applications of Liquid Crystal Thermography to Flow Boiling Heat Transfer in Mini-Channels," D. K. Hollingsworth. Proceedings of the 5th International Boiling Heat Transfer Conference, May 4-8, Montego Bay, Jamaica, 2003, keynote lecture VIII.
"Liquid Crystal Imaging of Flow Boiling in Minichannels," D. K. Hollingsworth. Keynote address, Proceedings of the 2nd International Conference on Microchannels and Minichannels, Rochester, NY, June 17-19, 2004, Number ICMM2004-2320, pp. 57-66.
"Fully Developed Nucleate Boiling in Narrow Vertical Channels," D. K. Hollingsworth, L. C. Witte, Y. Chin, Q. Lu, & M. Lakshminarasimhan, ASME J. Heat Transfer, August, 2005, Vol. 127, No. 8, pp. 941-944.
"Transition from Boiling Onset to Fully Developed Nucleate Boiling in a Narrow Vertical Channel," E. Daniel, D. K. Hollingsworth, L. C. Witte, 6th International Conference on Boiling Heat Transfer, May 2006.
Liquid Crystal Imaging of Surface-Tension-Driven Convection
Introduction
Liquid crystal thermography was used to produce perhaps the first thermal images of Marangoni convection. The technique requires a uniform flux boundary condition. The hexagonal pattern was clearly observed, as was the onset of motion.
Support
UH Institute for Space Systems Operations
Publications
T. Dutton, Liquid Crystal Imaging of Surface-Tension-Driven Convection, Undergraduate Honors Thesis, May, 1996.
L. R. Pate, Investigation of Surface-tension-driven Flows on a Uniform Flux Surface, Masters Thesis, December, 1999.
"Liquid Crystal Imaging of Surface-Tension-Driven Convection," T. W. Dutton, L. R. Pate & D. K. Hollingsworth, Proceeding of the Int. Mech. Engg. Congress and Exposition, Orlando, Florida, November, 2000.
The Effect of Martian Dust on Thermal Radiator Performance
Introduction
NASA envisions using thermal radiators to cool crew compartments on the surface of Mars. The purpose of this investigation was to determine the degradation in effective emittance of candidate radiator materials due to accumulation of simulated Martian dust (carbondale red clay). Radiator coupons and an apparatus for creating and uniformly applying dust were designed and constructed. Experiments were performed in an actively cooled vacuum chamber at the Johnson Space Center.
Support
NASA Johnson Space Center
Publications
"The Effect of Martian Dust on Thermal Radiators," D. K. Hollingsworth, L. C. Witte, J. Hinke, & K. Hurlbert, poster HLS46 at the Habitation 2004 National Conference, Orlando Florida, January 4-7, 2004.
"The Effect of Martian dust on Radiator Performance," D. K. Hollingsworth, L. C. Witte, J. Hinke, & K. Hurlbert, Proceedings of the ASME Summer Heat Transfer / Fluids Engineering Division Joint Conference, ASME HT-FED04-56577, July 11-15, 2004, Charlotte, NC.
"The Effect of Martian dust on Radiator Performance," D. K. Hollingsworth, an invited paper presented at the NASA Contamination and Coatings Workshop, August 3 ? 4, 2005 (proceedings from the workshop should be available as Powerpoint presentations).
"Reduction in the Emittance of Thermal Radiator Coatings Caused by the Accumulation of Simulated Martian Dust," D. K. Hollingsworth, L. C. Witte, J. G. Hinke, & K. Hurlbert, Applied Thermal Engineering, Vol. 26, No. 17-18, pp. 2383-2392, 2006.
Heat Transfer Enhancement Caused by Sliding Bubbles
Introduction
Large heat transfer coefficients are created by vapor bubbles sliding along the underside of a heated surface. Our work on the subject began with a liquid-crystal thermographic study of the heat transfer rates and liquid microlayer thicknesses created by sliding cap-shaped vapor bubbles. Later, a facility was constructed to directly measure the microlayer thickness using reflected laser light. Those measurements are described in the poster and resulted in thicknesses of 20 - 60 microns.
Support
Texas Advanced Research Program
Publications
B. B. Bayazit, A Thermographic Analysis of the Heat Transfer Mechanisms Generated by a Sliding Bubble, M. S. thesis, December, 2000.
Xin Li, An Experimental Study of the Microlayer Thickness and Kinematics of a Sliding Vapor Bubble, Ph.D. Dissertation, August, 2005.
M. Figueroa, The Evolution of the Microlayer Thickness Above a Sliding Vapor Bubble, M. S. Thesis, December, 2005
"Heat Transfer Enhancement Caused by Sliding Bubbles," B. B. Bayazit, D. K. Hollingsworth, L. C. Witte, Proceedings of the 35th National Heat Transfer Conf., No. NHTC01-11651, Anaheim, California, June, 2001.
"Heat Transfer Enhancement Caused by Sliding Bubbles," B. B. Bayazit, D. K. Hollingsworth & L. C. Witte, ASME J. Heat Transfer, June, 2003, Vol. 125, No. 3, pp. 503-509.
"Heat Transfer Between a Sliding Vapor Bubble and an Electrically Heated Surface," L. C. Witte, D. K. Hollingsworth, M. Figueroa, B. B. Bayazit, Proceedings of the 5th International Boiling Heat Transfer Conference, May 4-8, Montego Bay, Jamaica, 2003, Session VII.
"Measurement of the Thickness of the Liquid Microlayer Between a Sliding Bubble and a Heated Wall," Xin Li, D. K. Hollingsworth, L. C. Witte, Proceedings of the ASME Summer Heat Transfer Conference, ASME HT-2005-72349, July 17-22, 2005, San Francisco, CA.
"The Thickness of the Liquid Microlayer Between a Cap-Shaped Sliding Bubble and a Heated Wall: Experimental Measurements," Xin Li, D. K. Hollingsworth, L. C. Witte, ASME J. Heat Transfer, in press for September, 2006.
