Variations of saturation vapor pressure and evaporation rate of liquids with their vaporization enthalpy

TL;DR

This paper extends classical thermodynamic equations to include effects of electric-field-induced changes in phase transition enthalpy, deriving new formulas for vapor pressure and evaporation rate that match experimental data.

Contribution

It introduces modified Clapeyron and Clausius-Clapeyron equations accounting for non-expansion work and phase transition enthalpy variations due to electric fields.

Findings

A 1% decrease in vaporization enthalpy can increase vapor pressure by about 20%.

Evaporation rate can nearly double with small changes in vaporization enthalpy.

Theoretical models align well with experimental observations.

Abstract

The phase transition enthalpy of condensed materials can be altered by factors such as electric fields, and such variations in turn affect physical and chemical behaviors including phase equilibrium. However, due to the neglect of non-expansion work, the Clapeyron equation does not account for the effect of changes in phase transition enthalpy on equilibrium. In this paper, by analyzing the electric-field-induced changes in phase transition enthalpy and incorporating the non-expansion work performed on the system, we extended both the Clapeyron and Clausius-Clapeyron equations to explicitly include variations in phase transition enthalpy. Building upon these extensions, analytical expressions for the vapor pressure of liquids and for the total evaporation rate of sessile liquid droplets as functions of the change in vaporization enthalpy have been derived, showing that an approximately 1% decrease in vaporization enthalpy of a liquid can cause an increase of about 20% in its vapor pressure and an almost twofold increase in its evaporation rate. The theoretical predictions by the present equations were compared and found to be in good agreement with the experimental observations.