Abstract
Pool boiling experiments in microgravity performed during the past 3 decades demonstrate unanimously that up to a medium heat flux the overall heat transfer is nearly independent from gravity. So far it was assumed that buoyancy plays the essential roll for heat and mass transport expressed in the empirical correlations for technical applications. We refer in this paper on results of experiments performed with various liquids and heaters, using different carriers which provide low gravity like TEXUS rockets, aircraft KC135, and drops in the tower of ZARM and shaft of JAMIC, and as highlights, experiments during space lab missions. Beside the measurements of the experimental parameters like the liquid state, temperature and pressure, heat fluxes, and heater temperature, we observed the boiling process itself with movie films and videos. From these records we learned about the bubble dynamics, the mechanisms of heat and mass transport without gravity only generated by the bubbles themselves, and details about the boiling process itself not recognized up to this day. These findings are essential for a better understanding of the complex physical process, and are important for the formulation of empirical equations, and in future for numerical solutions to predict the heat transfer for technical applications.
