Condensation of Binary Mixture on a Flat Plate under a Microgravity Condition

Abstract

Experiments to determine the effect of surface tension on condensate flow of a binary mixture were carried out using an apparatus in which water-ethanol vapor mixture was condensed on a flat plate. The results of experiments carried out under a ground condition showed that the condensation patterns could be divided into three modes, i.e., filmwise, streaky and dropwise, corresponding to the vapor concentration and degree of surface subcooling. The results of microgravity experiments carried out in the MGLAB dropshaft showed that the condensed liquid in a microgravity condition formed into droplets with an increase in diameter by imbibing of the small droplets when streaky or dropwise condensation appeared under a ground condition. In this case, condensate flow in the opposite direction to that of the vapor flow by Marangoni convection was not observed under a microgravity condition. There was no significant difference in vapor temperature or pressure before and after the dropping.