Study on heat transfer in two-layer porous media with heat generation in porous media

Abstract

A mathematical model involving the mechanism of heat transfer in two-layer porous materials with the heat generation between two porous materials was studied. Open-cellular material with porosity (ϕ) ranging from 0.70 to 0.8 and a porous thickness of 0.02 m was used. The porosity of the first layer was kept at 0.70 but the second layer was varied in the range of 0.73 to 0.79. The heat generation (q̇gen) was a heat flux of 100 to 10,000 W/m2. The air velocity (uf) of 0.4 m/s flowed through the porous material in the x-direction. The governing equation used in the calculation was a two-phase (gas or fluid and solid) energy conservative equation. The heat radiative equation in porous materials was determined by the P1 approximation method. In the model, the temperature profiles (the gas (Tf) and the solid (Ts) phases) and the local energy balance (LEB) of both phases were reported. From the studies, the profile trend of the gas (Tf) and the solid (Ts) temperatures depended on the heat generation (q̇gen). However, the inverse results were obtained by the effect of the porosity of the porous material (ϕ). In the local energy balance (LEB) of the gas phase (or fluid), the main effective terms were the convection (CVF) and the interaction (INT) with almost no thermal conduction (CDF). The interaction (INT) and the heat radiation (RAS) in the solid phase gave a significant effect and there was insignificant conduction (CDS). This was described by both the gas (fluid or air) and solid phases becoming low thermal conduction for the heat transfer mechanism in the case of heat generation between the two-layer porous media. In both phases at the same position, the total energy balance becomes zero according to thermodynamic law.