Abstract The aim of this communication is to analyse the influence of water activity and total pressure on water evaporation. The system is composed of liquid and gas phases, separated by a plane surface, contained in a cylinder whose volume is regulated by a piston. Water activity is regulated by saturated salt solutions and pressure by the piston. The experimental device and procedures were defined to limit the temperature variation at the interface. A transient method is used. From a steady state, a volume increment is imposed; the resulting non-equilibrium leads to an increase in the partial pressure of water vapour to the equilibrium pressure imposed by the solution. Numerical calculation shows little variation in temperature in the gas-liquid interface under the experimental conditions. An evaporation model is adopted taking into account chemical potential discontinuity at the interface. The surface flux evaporation and chemical potential jump at the interface are deducted from the total pressure recording. In the neighbourhood of equilibrium, the surface flux of phase change is shown to be proportional to the chemical potential jump. The surface coefficient of evaporation increases with the total pressure of the gas phase and water activity.

中文翻译：

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化学势不连续性作用下水溶液表面水分蒸发率的实验研究——水分活度和气压的影响

摘要 本次交流的目的是分析水分活度和总压力对水分蒸发的影响。该系统由液相和气相组成，由平面分隔，包含在气缸中，气缸的容积由活塞调节。水活度由饱和盐溶液和活塞压力调节。实验装置和程序被定义为限制界面处的温度变化。使用瞬态方法。从稳定状态开始，施加体积增量；由此产生的非平衡导致水蒸气分压增加到溶液施加的平衡压力。数值计算表明，实验条件下气液界面温度变化不大。考虑到界面处的化学势不连续性，采用蒸发模型。从总压力记录中扣除界面处的表面通量蒸发和化学势跃变。在平衡附近，相变的表面通量显示与化学势跃迁成正比。蒸发的表面系数随着气相总压力和水活度的增加而增加。