STEADY-STATE HEAT AND MATTER EXCHANGE AT A PHASE INTERFACE

Equations are derived for the steady-state heat and matter fluxes through the boundary layer at a general phase interface; their range of validity is discussed, and the importance of the timescale of the observations is emphasized. Where only diffusive matter fluxes and conductive heat fluxes are involved, the results derived from irreversible thermodynamics remain valid for large departures from equilibrium. The theory includes the case where the location of the boundary layer is marked by an obstruction such as a membrane: the properties of the obstruction control the magnitudes of the fluxes but do not affect the thermodynamic forces. The theory is applied to transport processes at a plane liquid surface and at the surface of an aerosol droplet.