Numerical Simulation of Entropy Generation of Conjugate Heat Transfer in A Porous Cavity with Finite Walls and Localized Heat Source

Abstract

In this research, the entropy production of the conjugate heat transfer in a porous cavity with respect to heat source and solid wall’s locations has been studied numerically. Three different cases of the cavity with finite walls thickness and heat source locations are considered in the present study. For both cases one and two, the cavity considered has a vertical finite walls thickness, while the cavity with the horizontal finite walls thickness is considered for case three. For cases one and two, the left sidewall of the cavity is exposed to heat source, whereas the rest of this wall as well as the right sidewall are adiabatic. The upper and lower cavity walls are adiabatic. For case three, the lower wall is exposed to a localized heat source, while the rest of it is assumed adiabatic. The upper wall is cold, whereas the left and right sidewalls are adiabatic. The flow and thermal fields properties along with the entropy production are computed for the modified Rayleigh number (150 ≤ Ram ≤ 1000), thermal conductivity ratio (1 ≤ Kr ≤ 10), heat source length (0.2 ≤ B ≤ 0.6), aspect ratio (0.5 ≤ AR ≤ 2) and walls thickness (0.1 ≤ D1 ≤ 0.2 and 0.1 ≤ D2 ≤ 0.2) respectively. The results show that, the maximum values of the entropy generated from fluid friction develop close to the cavity wall-fluid interfacial, while the maximum values of the entropy generated from heat transfer develop nearby the heat source region. The average Bejan number (Beav) is higher than (0.5) for cases one and two. While for case three, it was found to be less than (0.5). Also, the results show that as the modified Rayleigh number, thermal conductivity ratio, heat source length and aspect ratio increased, the fluid flow intensity in the cavity increased. While, it decreased when the walls thickness increased. From the results, it is concluded that case three gives a higher heat transfer enhancement. The obtained results are compared against another published results and a good agreement is found between them.