Researches on Heat and Mass Transfer by Sublimation of Ice (2nd Report)

Abstract

In the first report, the three rate-determining steps of the sublimation of ice had been clarified by the experiments. In this paper, we investigated the mechanisms of mass transfer in each step and obtained the following results. (1) The mass transfer rate of free molecular flow shown by Hertz-Kundsen's equation should be corrected by the effect of net mass flow to the velocity distribution at the low pressure side. The correction coefficient was calculated and was verified by the experiments.(2) The condition of transition of rate-determining step from the diffusion region to the phase change region was decided by the saturation of the water vepor on the ice surface.(3) The relation among the degree of super heat, the increasing of surface area of ice and the mass transfer rate of sublimation was investigated from the observation of ice surface in the region determined by the rate of phase change.