Boiling Under Microgravity Conditions
Space applications of boiling heat transfer can be found in the areas of thermal management, fluid handling and control, power systems, on-orbit storage and supply systems for cryogenic propellants and life support fluids, and for cooling of electronic packages for power systems associated with various instrumentation and control systems. Studies of boiling under low gravity conditions can be grouped into two periods - the studies that were conducted in the nineteen sixties, and the studies that have been conducted during the last two decades. Although the earlier studies provided valuable insights into the phenomena, the duration of the experiments at low gravity was only a few seconds and did not represent quasi-static conditions. In the recent studies boiling experiments at gz/ge ~ 10-2 and gz/ge ~ 10-4 have been conducted for much longer durations. However, these experiments have often yielded contradictory data and have not been able to provide an understanding of the phenomena up to a level that is necessary for development of predictive models or correlations. Both experimental and analytical/numerical studies covering pool and flow boiling are reviewed. New insights gained from these studies are highlighted.