Abstract
This work examines the effects of gravitational acceleration on the flow boiling process. A test facility focusing on an annular heat exchanger was designed, built out of borosilicate glass, and flown on NASA's KC-135 reduced gravity airplane creating unique visual and quantitative data. These data were then analyzed using a resistance type heat transfer model and five different zero gravity flow regime maps. Results from this analysis included: (i) presenting zero gravity data that correlated poorly with an Earth based flow regime map; (ii) predicting that the maximum two-phase heat transfer coefficient would occur near the location the boiling fluid reached a saturated state, which also corresponded with the location of maximum nucleate boiling; and (iii) illustrating that the uncertainty in the calculated heat exchanger performance parameters due to the zero gravity flow chosen were only minor. This analysis also supported the concept that two-phase thermal control systems have tremendous potential for space applications due to excellent heat transfer enhancement.
Westheimer, David Thomas (2000). Visualization of flow boiling in an annular heat exchanger under reduced gravity conditions. Master's thesis, Texas A&M University. Available electronically from
https : / /hdl .handle .net /1969 .1 /ETD -TAMU -2000 -THESIS -W32.