Vapor-Liquid Counterflow in Heterogeneous Porous Media

Abstract

Based on a continuum description, the effects of permeability heterogeneity on steady state, countercurrent, vapor-liquid flow in porous media are analyzed. It is shown that the capillary heterogeneity induced acts as a body force, that enhances or diminishes gravity effects on heat pipes. Selection rules that determine the particular steady states reached in homogeneous, gravity-driven heat pipes are formulated. It is shown that the ìinfiniteî two-phase zone terminates only if a substantial change in permeability occurs somewhere in the medium. The two possible sequences that result, namely liquid - liquid dominated - dry or liquid - vapor dominated - dry find applications in geothermal systems. Finally, it is shown that weak heterogeneity affects only gravity-driven flows, but stronger variations in permeability give rise to significant capillary effects.