Estimation of comprehensive thermal performance for conjugate natural convection inside a dome-shaped porous chamber holding a solid cylinder

Abstract

The present work aims to investigate flow patterns and control of heat transfer by studying conjugate natural convection behavior inside a dome-shaped permeable chamber enclosing a heat-conducting solid cylinder. The application of this study includes heat transfer equipment such as heat exchangers, steam generator tubes, solar and wind power collector, nuclear reactor, electronic components, etc. The dimensional formulations of Navier-Stokes, thermal energy equations of the porous domains, and the solid cylinder have been used to solve the problem numerically using the finite element technique under realistic boundary conditions. The Darcy-Brinkman-Forchheimer model is used for the porous domain to perform the simulation-based study. Parametric computations have been performed for a large variety of Rayleigh numbers (103 ≤ Ra ≤ 108), several solid materials for the cylinder with varied thermal conductivity (7.99 W/mK ≤ ks ≤ 94.90 W/mK), four different positions (0.25L ≤ yc ≤ L) and different diameters of the cylinder (0.2L ≤ D ≤ 0.40L) inside the chamber, and different inclination angles of the chamber within the range of 0° ≤ θ ≤ 45°. The results in quantitative measurement of average Nusselt number change and qualitative visualization of streamline and isotherms are examined for maximum thermo-fluid performance inside the chamber. The outcomes demonstrate that the dome shape allows better fluid circulation within the chamber, resulting in improved convection heat transfer with a remarkable effect on the overall heat transfer rate of the system under the optimum condition. Besides, both conduction and convection-dominated heat transfer inside the porous cavity strongly depend on the Rayleigh number selection.