Numerical Investigation of Conjugate Heat Transfer From a Solid Torus

Abstract

The present work comprehensively investigates conjugate heat transfer in a vertically oriented torus through numerical analysis using Ansys Fluent. A solid torus made of aluminum, having a constant surface temperature of 450 K, is allowed to cool using ambient air, whose temperature is 300 K. The combined influence of free convection and radiation heat transfer has been considered here. Independent parameters such as Aspect Ratio (D/d) of 2.5,5,7.5; Rayleigh number for the laminar regime in the range of 103–107 and surface emissivity ranging from 0 to 1 have been selected for the numerical study. Continuity, Momentum, Energy, and Radiation Equations were solved numerically using finite volume method (FVM). Due to the high temperature difference between the ambient air temperature and torus surface (150 K), the thermo-physical properties of the fluid were calculated using a polynomial function of temperature to achieve more accurate results. It has been observed that each parameter has a substantial impact on the overall heat transfer and also, at a higher Rayleigh number of 107 and with an increase in emissivity, both radiation and convection have a considerable role in the overall heat transfer. Temperature and velocity contours have been plotted to visualize the consequences of the parameters on overall heat transfer. Using a nonlinear regression model of the obtained results, a correlation for the overall Nusselt number has been formulated, which can be beneficial to industrial engineers.