Abstract
An equation was developed to estimate the evaporation rate of a volatile liquid in a flowing airstream and tested against experimental data. The equation requires only the molecular weight, vapor pressure, air velocity, pool size, ambient pressure, and liquid temperature, or estimates of these quantities, to approximate the overall evaporation rate in mass/time/unit area. The equation was developed by solving the partial differential equations describing the mass balance of a differential element above the liquid and includes fits of the diffusion coefficient based on classical kinetic theory of gases. The experiments tested the evaporation rate of 13 different compounds at different temperatures and airflow rates, and regression fits were made of the data. Both the regression fit and the theoretical equation fit the data well within an order of magnitude. The theoretical equation thus provides an approximation of the evaporation rate for low vapor pressure (i.e. 35 Torr of 5% of the ambient pressure) liquids with a minimum of information about the liquid..
Keywords: