Pages 475-476
In subcooled pool boiling of water under microgravity obtained by a parabolic flight of aircraft, coalesced bubbles did not detach from the heating surface until the heating surface was burned out and the heat flux was 200∿400 percent higher than the widely accepted predictions. The microgravity duration was about 20 seconds and the level was 0.01∿0.04g. According to the observed bubble behaviors, same pool boiling was performed with attached bubbles on the heating surface on the ground. The burnout heat fluxes obtained were well agreed with those under the microgravity. An effect of heating period on the burnout heat flux was investigated in the ground experiment with bubble holder. The burnout heat fluxes decreased rapidly with heating period over about 20 seconds and became constant for long heating period. The constant burnout heat fluxes were roughly coincident with those calculated by the conventional predictions.
