Subcooled pool boiling of water on a downward-facing stainless steel disk in a gap

Abstract: Pool boiling is experimentally studied on a relatively large downward-facing surface with heated stainless steel disk diameters of D =100 and 300mm in confined space at atmospheric pressure using water as the working fluid. The bulk working fluid is subcooled. The gap size s can be adjusted to 10, 15 and 20mm for D =100mm and 0.9–77mm for D =300mm. We found that pool boiling under the present condition is far weaker than that occurring on an upward-facing surface. Furthermore, we found that the larger the diameter of the stainless steel plate, the weaker the pool boiling heat transfer. The heat transfer rate may be predicted by the Kutateladze correlation for s >20mm and by its modified form for s <20mm for both D =100 and D =300mm. Two different typical bubble circulation motions are found. Type I motion occurs with a probability of 90.9% and type II occurs with a probability of 9.1% according to the statistical calculations. Most coalesced bubble diameters are from 90 to 100mm for D =100mm and from 100 to 200mm for D =300mm. [Copyright &y& Elsevier]