Evaporation and Condensation in Porous Media : A Comprehensive Non-Equilibrium Model
This paper deals with the macroscopic description of heat transfer in a porous medium subjected to a liquid-vapor flow with phase change. Considering local thermal non-equilibrium between the three phases, the method of volume averaging is used to derive a three-temperature macroscopic model. A closed form of the evaporation rate is derived depending on effective properties and averaged temperatures. The volume averaging method provides six local closure problems that allow to compute all the effective transport coefficients introduced in the average model. Closure problems are solved for simple unit cells and some analytical results are presented. A comparison between averaged temperatures obtained from numerical experiments at the pore-scale, and average temperatures obtained from the macroscopic model, is performed. This comparison illustrates the validity and the
practical interest of the modelling approach.