Abstract
Pool boiling experiment with a platinum wire was performed in earth and micro gravity. Bare surface and fouling surface with scale of calcium carbonate was used. The wettability on the scale surface was higher than that on the bare surface. The critical heat flux (CHF) was measured and movies of the bubbling were taken with a high-speed video camera. The more vigorous bubbling was observed on the scale surface compared to that on the bare surface at the same heat flux. The scale surface became thermal resistance and the boiling curve on the scale surface eventually shifted to the right side of that on the bare surface. However, the critical heat flux on the scale surface was higher than that on the bare surface. On the scale surface, the departure diameter of bubbles is relatively smaller than that on the bare surface. The smaller diameter of bubbles detaching from the scale surface is considered to be due to the high wettability. As the result, the coalescent of bubbles near the surface was prevented and the CHF was delayed and increased on the scale surface compared to that on the bare surface.
