Calculation and analysis of excess adsorption and surface tension of aqueous surfactant solutions under pool boiling conditions

Abstract

In order to realize the theoretical calculation of surface tension of aqueous surfactant solution under pool boiling conditions, the relationships between surfactant adsorption and bubble behaviors were analyzed. The models of surfactant excess adsorption at liquid-vapor interface and surface tension of aqueous surfactant solution were developed. The parameters in developed models were determined in detail by experiments with ionic surfactant of sodium dodecyl sulfate (SDS) and non ionic surfactant of Triton X-114. Based on the established models, the local surfactant excess adsorption and surface tensions under pool boiling conditions were calculated and analyzed. The results show that bubble behaviors and surfactant adsorption generally take place simultaneously. In low heat flux range, the heat flux has little influence on the excess adsorption and surface tension, while in high heat flux range, the excess adsorption decreases and the surface tension increases significantly with the increasing heat flux. The bubble growth is so fast in high heat flux range that the surfactant adsorption at the liquid-vapor interface has no enough time to reach equilibrium, which leads to the decrease of excess adsorption and the increase of surface tension with the increasing heat flux.