Evaporative convection in a horizontal liquid layer under shear-stress gas flow

Experimental investigation of convective processes within horizontal evaporating liquid layer under shear-stress of inert gas flow is presented. Average evaporation flow rate of HFE-7100 liquid layer under Nitrogen gas flow is measured with the help of two independent methods. Influence of the gas velocity, the gas/liquid temperature and the liquid depth on the evaporation flow rate has been studied. At increasing of the liquid depth the average evaporation flow rate has a local maximum. With growth of the gas/liquid temperature from 20°C to 40°C the local maximum is shifted from 3 mm to 5 mm of the liquid depth. Visualization and analysis of the flow patterns on the gas-liquid interface have been performed. It is found out that the maximum evaporation flow rate is achieved at a stable and uniform convective flow within the liquid layer in the direction opposite to the gas flow. The results reported in this paper is a contribution to the preparation of the experiment on the International Space Station in the frame of the scientific project "Convection and Interfacial Mass Exchange" (CIMEX) of the European Space Agency.