PERCOLATION OF A BOILING LIQUID IN A POROUS-MEDIUM

The percolation of a boiling liquid was investigated in a porous mediu m as the pressure at its boundary was reduced below the saturation pre ssure corresponding to the initial temperature of the system. In speci fying the coefficients of phase permeability, two limiting schemes wer e adopted for the percolation of a vapor-liquid mixture. One scheme as sumes that the liquid is stationary, and the permeability coefficient for vapor is taken on the basis of Kozeny's equation. The other scheme is based on the idea of ''gas bearing'', according to which vapor mai nly evolves and flows along the walls of the porous medium. It is show n that when one uses the former scheme and the porous medium is initia lly completely filled with the liquid, the vapor-liquid mixture occupi es a finite zone. With the latter scheme, this zone is of infinite ext ent. Conditions are derived for the permeability coefficients, which d etermine whether phase transitions will occur in the bulk or at the St efan boundary.