Cooling of a Very Hot Vertical Surface by a Falling Liquid Film

Abstract

The present study analyzes the cooling of a very hot vertical surface by a falling liquid film. An analytical model is developed to characterize this phenomenon in three distinctive regions: a dry region ahead of the wet front, a sputtering region immediately behind the wet front, and a continuous film region further upstream. The analysis leads to predictions of the wet front velocity, the sputtering length, and the temperature profiles with respect to the wet front. The heat transfer mechanisms are shown to be dependent upon two temperature parameters characterizing the initial wall temperature and the temperature range for sputtering, and two Biot numbers comparing the convective heat transfer in the liquid film region and the sputtering region with longitudinal heat conduction. The predictions are in good agreement with existing experimental results.