Evaporation and condensation of falling binary liquid film

Abstract

This paper investigates a numerical analysis of coupled heat and mass transfer during the simultaneous evaporation and condensation in the presence of a binary liquid film flowing on one of two parallel vertical plates under mixed convection. The first plate of a vertical channel is externally insulated and wetted by a binary liquid film while the second one is dry and isothermal. The liquid mixture consists of water (the more volatile component) and ethylene glycol while the gas mixture has three components: dry air, water vapour and ethylene glycol vapour. The conducted simulations enable the analysis of the heat and mass transfer during water evaporation and ethylene glycol condensation for different inlet gas properties. It is found that an increase of the inlet vapour concentration of ethylene glycol enhances the water evaporation while the increase of the inlet vapour concentration of water slightly enhances the ethylene glycol vapour condensation. The increase of inlet gas temperature considerably benefits the water evaporation and slightly influences the ethylene glycol condensation.