NUMERICAL INVESTIGATION OF THERMOFLUID FLOW CHARACTERISTICS WITH PHASE CHANGE AGAINST HIGH HEAT FLUX IN POROUS MEDIA

摘要

This study numerically evaluates thermofluid flow characteristics in porous media by a newly developed "modified two-phase mixture model" applying a two-energy model instead of an one-energy model. In a single-phase flow case, thermal nonequilibrium between a solid phase and a fluid phase is observed in the area where inlet heat conducts from a heating wall and further convective heat transfer is more active. Though the degree of thermal nonequilibrium has a positive correlation with the increase inflow velocity and inlet heat flux, the degree is very low and can be ignored, from an engineering perspective. In a case of two-phase flow, the thermal nonequilibrium is remarkable in the two-phase region because the solid-phase temperature in this region is far beyond saturation temperature. A difference between these two models is obvious especially in the two-phase flow case, so that the numerical simulation with the two-energy model is indispensable under the high heat flux conditions of over 1 MW/m~2.