The "Heat-Pipe" Effect in Vapor-Dominated Geothermal Systems

Abstract

White, Muffler, and Truesdell (1971) and Truesdell and White (1973) devel oped a conceptual model of transport in vapor-dominated geothermal zones. The main theme of the model is that coexisting liquid and vapor phases form a counterflowing convection system similar to that observed in a heat pipe (Dunn and Reay, 1976). hypothesized that water evaporates from a deep water table, passes upward through the formation, and condenses at an impermeable cap rock, effectively transferring the latent heat of boiling through the formation. The liquid water then percolates downward, completing the cycle. The physics involved in the flow system is illustrated in the following analysis of an idealized one-dimensional, homogeneous, 2 km deep vapordominated zone which is bounded below by a water table which has a temperature of 236OC.