Measurements of the evaporation coefficient of water based on molecular gas dynamics

Abstract

We propose a novel method for measuring the evaporation coefficient of water using a sound-resonaiice experiment based on the theory of molecular gas dynamics. The evaporation coefficient is one of the parameters contained in the kinetic boundary condition. The evaporation coefficient of water is determined according to the pressure amplitude of the resonant sound wave in a cylindrical space bounded by a sound source and a vapor–liquid interface. The use of the sound wave enables us to conduct the experiment in a weak nonequilibrium state. By comparing the pressure amplitude with the results from a linear acoustic theory, including the effect of the evaporation coefficient on the amplitude variation, we demonstrate that the evaporation coefficient of water is approximately 1.0 near 300 K.