Liquid-Vapour Phase Change Rates and Interfacial Entropy Production

Abstract

Measurements have recently been made of the thermodynamic conditions at the interface during steady state, liquid-vapour phase transitions. In these stationary, nonequilibrium states discontinuities were recorded in the temperature and other intensive properties. Independently of whether evaporation or condensation was taking place, it was found that the interfacial temperature was higher in the vapour phase than that in the liquid. The expression for the interfacial entropy production during these phase change processes is formulated using statistical rate theory. The interfacial entropy production rate is not a minimum when there is a phase change process taking place, but if the system is required to be closed (no net phase change), the interfacial entropy production rate is a minimum. States of minimum entropy production rate can exist arbitrarily far from equilibrium, provided a certain relation exists between the properties of the substance undergoing the phase change. For water, it is found that states of minimum entropy production rate are only slightly displaced from the stationary, nonequilibrium states existing when a net phase change rate is present.

Onset of Marangoni convection for evaporating liquids with spherical interfaces and finite boundaries

“…If we use an expression for the evaporation flux j ev from statistical rate theory [17,18], which has no fitting parameters, we can take the derivative with respect to the liquid or vapor temperature. This enables us to write the evaporation flux and enthalpy of vaporization, which are dependent on the liquid and vapor temperatures, as…”

“…The statistical rate theory expression for j ev is listed in the Appendix and a detailed derivation and description can be found in Refs. [17,18].…”

“…The derivative of the evaporation flux with respect to the liquid or vapor temperature, required for Eq. (77), can be calculated using an expression for the evaporation flux j ev from statistical rate theory [17,18] [Eq. (A1)], which has no fitting parameters, as noted above.…”

Thermal Properties of Deuterium Oxide near the Triple Point Predicted from Nonequilibrium Evaporation

“…The function of ∆s LV can be simplified as, [8][9][10][11][12][13][14] )] ] (4) where T I V is the local interfacial vapor temperature, P I V is the local vapor-phase pressure, and q vib is the vibrational partition function in eq 5. …”

“…18 point. Thus, the specific enthalpy of evaporation of D 2 O could be expressed as, h fg ) RT 2 d ln P s dT (10) where R is the gas constant. After the equations for P sat are substituted into eq 10, one may obtain an expression for h fg corresponding to each expression for P sat .…”