A Molecular Fluiddynamical Study of Phase Change Phenomena of a Vapor in a Wide Range of Themally Non-equilibrium State

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This paper aims to determine the condensation coefficient of methanol vapor under vapor-liquid nonequilibrium states. A shock tube avaiable in a state from initially normal to high temperatures has been made and it is used for the measurement of the growth of a liquid film formed on the endwall surface of the tube in a shock wave reflection region. It is found that the shock tube satisfies requirements for the experiment and the liquid film grows uniformly on the wall surface in a wide range of temperatures of liquid film and vapor.The condensation coefficient of methanol vaporn has been determined from the growth of liquid films at initially normal temperatures(286.3K〜299.6K) and higher ones(323.3K〜324.4K). It is clarified that the condensation coefficient is strongly dependent on both the ratio of vapor and liquid film temperatures and the ratio of number densities of vapor and saturated vapor at the vapor -liquid interface.For the same temperature and number density ratios, the higher is the liquid film temperature, the smaller becomes the condensation coefficient, and it decreases with the increase of the number density ratio. The condensation coefficient becomes large as the both ratios approach to unity, that is,the state does to an equilibrium one.