Nucleate Pool Boiling eXperiment (NPBX) in microgravity: International Space Station

A series of nucleate pool boiling experiments were conducted in the Boiling Experimental Facility (BXF) located in the Microgravity Science Glovebox (MSG) on board the International Space Station (ISS) during the period March-May, 2011. Nucleate Pool Boiling experiment (NPBX) was one of the two experiments housed in the BXF. Five cylindrical cavities were formed on the surface with four cavities located at the corners of a square and one in the middle, to study bubble dynamics and initiate nucleate boiling. The results of the experiments show that at low superheats, bubbles generated on the heater surface slide and merge to yield a large bubble located in the middle of the heater. The data are useful for calibration of results of numerical simulations. Any correlations that are developed for nucleate boiling heat transfer under microgravity condition must account for the existence of vapor escape path from the heater, relative size of the large bubble and heater, and the size and geometry of the chamber used.