A study of steady-state steam-water counterflow in porous media

Vapor-liquid counterflow in porous media arises in processes such as heat pipes, oil recovery and geothermal systems. Previous studies analysed these phenomena in separate contexts. This paper presents a unified description from which previous models result as limiting cases. The analysis includes capillarity, heat conduction, and Kelvin effects. The importance of each term to various processes is examined. Significantly, it is found that the critical heat flux is not constant but increases with decreasing permeability. A threshold permeability is identified below which steady states may not exist. Analogous conclusions are reached regarding liquid-dominated geothermal systems. 24 refs., 15 figs