Liquid Film Boiling Heat Transfer in the Presence and Absence of Gravity

Abstract

Liquid film boiling is an effective method of heat removal from a flat surface and has many terrestrial applications. It is an attractive technique for microgravity thermal control but cannot be sustained in the absence of gravity, according to theoretical prediction. However, this has not been experimentally confirmed to date for various reasons such as difficulty of performing experiments in microgravity and the associated cost. This paper presents new terrestrial and microgravity experimental results of liquid film boiling in a radial heat transport device. The microgravity experiments were performed on board a variable gravity parabolic flight. The data were expected to show that absence of gravity results in very high heater surface temperatures and eventual dryout compared to results in the presence of gravity at a given heat flux. However, this only occurred during the transition phase from 1.8-g to 0-g in the parabolic maneuver and the heater temperatures remained normal during the 0-g phase. Despite this, the results still add valuable information to the overall understanding of the liquid-vapor phase-change process in the absence of gravity. They have also laid the foundation for further experimental work such as using electrohydrodynamic (EHD) conduction pumping to facilitate liquid film boiling in microgravity, which we have presented in another study.