Optimization of heating-cooling generators with porous components/cryogenic conductors on natural convection in a porous enclosure: Using different two-phase models and single-phase model and using different designs

Abstract

Abstract In the present study, the effect of the use of heating and cooling generators along with cryogenic conductors on flow and heat transfer characteristics in a porous chamber are investigated. The finite volume method (FVM) is used to simulate the phenomena. Single-phase and two-phase models (Mixture model and Eulerian-Eulerian model) have been used to predict heat transfer. Water-Copper oxide nanofluid is assumed to be Newtonian, incompressible, and steady. Several cases have been investigated in order to evaluate the heat transfer rate and streamlines visualization accurately. Investigations include a change in the number of heating and cooling generators, a change in the size of the cryogenic conductors, and the use of porous components as an alternative to cryogenic conductors. The volume fraction is assumed to be constant in the whole simulation and is 3%. The Rayleigh and Darcy numbers ranges are 104 ≤ Ra ≤ 107 and 10−2 ≤ Da ≤ 10−4, respectively. The Darcy-Forchheimer model is used for fluid flow and heat transfer in a porous medium. The results of this study are compared with the results of a regular enclosure that has been studied by many previous researchers. The findings show that the effect of using heating-cooling generators is favorable and that cryogenic conductors can also help to improve heat transfer. However, in some conditions using a regular porous enclosure yields better results. In addition, the difference in the results of single-phase and two-phase models depending on the operating conditions can be low or high. The goal is to achieve the highest heat transfer rate using the available tools. It is hoped that using the results of this research can be a useful guide to better understanding the phenomena and optimum and better designs.