NUMERICAL STUDY ON FREEZING HEAT TRANSFER IN WATER-SATURATED POROUS MEDIA

Abstract

Numerical investigations have been carried out to examine the characteristics of unsteady freezing heat transfer in water-saturated porous media. As a physical model, a two-dimensional vertical cavity is considered. The temperature of the porous media is initially maintained at the temperature of the hot wall. The vertically opposite wall is abruptly cooled below the freezing temperature. The equation of momentum includes Forchheimer's extension as the resistance to flow in the porous media. For the governing equations in the frozen and unfrozen porous layers, the transformations of variables are performed by the boundary fixing method, and the finite-difference equations are obtained by integrating the governing equations over the control volume. The successive overrelaxation method is utilized to solve the equations numerically. Modified Nusselt numbers are introduced to characterize the unsteady freezing heat transfer in water-saturated porous media. The flow patterns and the temperature distributions are described in the cavity treated herein. The effects of Stefan number and of the ratio of cooling to heating temperature are discussed for the unsteady freezing heat transfer.