An experimental study of critical heat flux (CHF) in microgravity forced-convection boiling

Pool and forced-convection boiling of FC-72 was conducted in earth gravity and microgravity. A platinum wire heater was used to generate bubbles and provide simultaneous measurement of the heater surface mean temperature. An electrical circuit was built to control the temperature of heater surface. Boiling curves of FC-72 for different flow rates were obtained in the experiment. By using photographic visualization, it was observed that the microgravity environment decreased the critical heat flux (CHF) significantly and force the boiling to switch to transition or film regime. With an increase of the flow rate, the CHF increased and the boiling curves moved upward in both terrestrial gravity and microgravity. In this study, it was also found that the forced convection tends to offset the microgravity effect on CHF when the flow rate was sufficiently high.