Modeling liquid evaporation in nanopore and the effect of noncondensable gas
The liquid evaporation process in a nanoporous medium under the influence of noncondensable gasses is a fundamental problem in energy and chemical engineering.Based on the kinetic theory of gasses and the moment method for the Boltzmann equation,the flow resistance of vapor in nanoscale pores or channels was analyzed,and a theoretical model for the single-component evaporation problem was proposed.Further,direct simulation Monte Carlo was performed to study evaporation in the presence of noncondensable gasses.An empirical correlation was established to predict the liquid evaporation rate.The results showed that nanoporous evaporation can be divided into three parts:vapor flow within the nanopore or channel,kinetic expansion out of the nanopore,and convection-diffusion flow of vapor downstream.The porosity and aspect ratio of the vapor-occupied pore section have a profound influence on the evaporation rate.Moreover,the effect of noncondensable gas is more outstanding at larger porosities than at smaller porosities.The liquid evaporation rate can be reduced by 50％when the vapor-occupied pore section has an aspect ratio of 2.5.The model of single-component evaporation combined with the empirical correlation for dimensionless evaporation rate can predict direct simulation Monte Carlo results within 10％.
nanoporeevaporationnoncondensable gasdirect simulation Monte Carlokinetic theory of gasses
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