An analysis of the wet-side heat-transfer coefficient during rewetting of a hot dry patch

A physical model for the rewetting of a hot dry patch is proposed. The mechanisms governing the rate of resorption of the dry area are the conduction of heat from the dry to the wet area and the removal of this heat by a large local heat-transfer coefficient. The coefficient is assumed to be directly proportional to the cube of the difference between the surface and saturation temperature (h = RT^ß). The wall temperature at the interface between the wet and dry side is assumed equal to the sputtering value, and the cubic relationship between the heat-transfer coefficient and surface temperature difference is assumed valid up to this temperature. Experimental data from Harwell on rewetting rates for a stainless steel tube in a steam environment at various pressures are analysed to determine R. The energy equations are solved numerically by a quasi-linearization technique combined with the finite-difference method.