New dimensionless correlation for mass transfer at evaporation of open liquid surface in natural convection

Abstract

The evaporation process is influenced by the properties of gas and liquid. These include the properties of gas, temperature, humidity, characteristic velocity, turbulence intensity of the gas and total pressure of the gas above the liquid surface; and the properties of the liquid, surface temperature, convection and surface area of the liquid. Depending on the properties, the evaporation process can be categorized based on different cases. A new dimensionless equation has been created that gives the value of the evaporation rate for steady-state gas and liquid conditions in natural convection. For this, we used the measurement results from the literature, which were reported with appropriate data. In addition to the Sh and Ra number, the equation includes the Sc number, the gas and liquid temperatures, the partial vapor pressures of the gas, the total pressure of the gas above the liquid surface and the equivalent characteristic length of the liquid container. Compared with the correlations available in the literature for the evaporation rate, the new dimensionless equation approximated the measurement results the best, with an average relative error of 9.5%.