Steady-State Pool Boiling Heat Transfer to Saturated Liquid Helium at Atmospheric Pressure

Abstract

The effects of surface roughness and inclination on pool boiling heat transfer in saturated liquid helium at atmospheric pressure were experimentally established. It was found that the nucleate boiling heat transfer increased as the surface roughness increased. Furthermove, increasing the surface inclination increased the nucleate boiling heat transfer in the low heat flux region. The two-phase boundary-layer analysis of saturated film boiling was found to underestimate the heat transfer coefficient, but by modifying the heat transfer surface length, the effects of surface superheat and the surface inclination could be correctly predicted. The surface roughness does not affect the critical heat flux, but the surface orientation has a pronounced effect on it. The existing correlations predict the orientation dependency of the critical heat flux reasonably well. The temperature at the minimum-heat-flux is affected by neither the surface roughness nor the orientation.