Evaporation Heat Transfer of Single Hydrous Ethanol Droplet Impacting on a Heated Wall

Abstract

The phenomenon of droplet impact on heated wall along with its evaporation is encountered in a variety of scenarios in industrial production. The present work aims to experimentally study the evaporation heat transfer of single hydrous ethanol droplet impact on a heated wall at saturation temperature under lower velocity. Its dynamic evolution after the impact, along with the stable adhesion morphology, was studied at different wall temperatures. The characteristics of its heat transfer and evaporation were analyzed by focusing on the effects of wall temperature, ethanol concentration, and adhesion morphology. The results show that the wall temperature has little effect on the spreading time, but significant on the spreading area and retraction. The "pining effect" of the hydrous ethanol weakens with the ethanol concentration, until it completely disappears. The film thickness along with its contact angle in adhesion evaporation shows a linear decrease accompanied by oscillations at the later stage. Evaporation heat transfer rate gradually increases with the wall temperature and ethanol concentration, and shows a multiple power function with them. The saturation temperature in evaporation gradually increases with the wall temperature, while the ethanol concentration has a minor effect. The average heat flux in evaporation can reach the magnitude of 10E5, and increases with the wall temperature and ethanol concentration.