Investigation of condensate droplet movement in marangoni condensation of ethanol-water mixtures by infrared thermography

Abstract

Marangoni condensation is a phenomenon that occurs during the condensation of a positive system with binary vapor mixtures. Applying infrared thermography to the investigation of Marangoni condensation could not only help to obtain quantitative data on droplet movement but also establish the relationship between the droplet velocity and surface temperature of condensate droplets. In this study, the droplet movement in Marangoni condensation of ethanol-water mixtures was experimentally investigated by infrared thermography. The effects of vapor concentration, impinging cooling water temperature, and vapor velocity on droplet velocity were investigated, and the relationships between droplet velocity, temperature gradient, and surface tension gradient were studied. The results indicated that the droplet velocity first increased and then decreased with the increase in the droplet radius. The maximum droplet velocity decreased with the increase in vapor concentration and vapor velocity. As impinging cooling water temperature increased, the droplet velocity decreased, and the decline was more obvious at the high impinging cooling water temperature. In addition, the droplet velocity increased and then decreased with the increase in the surface temperature gradient and surface tension gradient.