Characterization of Interfacial Mass Transfer Rate of Stored Liquids

A thermodynamic analysis of the two-phase physics involving a liquid–vapor combination has been studied under the regime of conjugate heat and mass transfer phenomena. An experiment has been designed and performed to estimate the interfacial mass transfer characteristics of a liquid–vapor system by varying the liquid temperature. The experimental setup consists of an instrumented tank partially filled with water and maintained at different temperatures. The evaporation of liquid from the interface and the gaseous condensation has been quantified by calculating the interfacial mass transfer rate for both covered and uncovered tanks. The dependence of interfacial mass transfer rate on the liquid–vapor interfacial temperature, fractional concentration of the evaporating liquid, the surface area of the liquid vapor interface, and the fill level of the liquid has been established through the present experimental study. An estimation of the overall mass transfer rate from the interface due to a concentration gradient shows an analogy with the multiphase heat transfer that takes place across the interface due to temperature gradient. It was seen that at low fill levels and with a temperature difference of about 30 °C between liquid and ullage, the mass transfer rate of a closed system was nearly doubled when compared to its open system counterpart.