Natural Convection Heat transfer in a Concentric Annulus Vertical Cylinders embedded with Porous Media

Abstract

The prediction of heat transfer due to natural convection in vertical enclosures of concentric cylindrical annular form has received considerable attention because of numerous heat transfer applications. A Numerical investigation of the natural convection heat transfer between two isothermal concentric vertical cylinders inserted with porous medium was studied. The numerical solutions were obtained for a Rayleigh number (Ra) ranging between (300-400) and Prandtl number=0.7. Finite volume technique with the SIMPLE algorithm was used to solve the Navier–Stokes and energy equations using Fluent v.15.0 software. One type of boundary conditions has been considered for the inner cylinder, where its wall was heated by applying a uniform heat flux with different ranges (300-450W/m2). The predicted results were presented in terms of temperature profiles and stream functions for different ratio (r/R) and Ra to show the behavior of the temperature fields and fluid flow. The simulated data of the average Nusselt number values have been compared under the same boundary conditions to similar results of previous works and good agreement was obtained. The predicted results revealed that the average Nusselt number was a function of varied Rayleigh number and non-dimensional parameter of (r/R). Results also showed an increase in the natural convection as heat flux increases leads to an improve in the heat transfer process and the average Nusselt number increases with Ra and (r/R) ratio increases.