Pool Boiling Heat Transfer in Microgravity

The pool boiling heat transfer of FC-72 on a plain plate with a heating area of 15*15 mm(2) in different pressure and subcooling has been studied experimentally both in normal gravity on the ground and in microgravity aboard the Chinese recoverable satellite SJ-8. A quasi-steady heating method is adopted, in which the heating voltage is controlled as an exponential function with time. Three modes of heat transfer, namely single-phase natural convection, nucleate boiling, and transition boiling, are observed, while the nucleate pool boiling are the major subject for discussion in the present paper. In normal gravity, the present data is compared with those obtained by other researchers, and a satisfactory agreement is evident and warrants reasonable confidence in the data. Compared with terrestrial experiments, the boiling curves in microgravity are considerably gentle, and CHF is no more than 40% of that in terrestrial condition. In microgravity, influences on boiling curves of the pressure and subcooling are similar with those in normal gravity, namely that the heat transfer coefficient and CHF will increase with subcooling for the same pressure, and that they will also increase with pressure for the same subcooling.