Natural convection in a horizontal cylindrical annulus using porous fins

Abstract

PurposeThe aim is to study the effects of fin conductivity ratio, Darcy number, and Rayleigh number on the average Nusselt number for fins made of porous material when attached to the inner cylinder of the annulus between two concentric cylinders. The paper also aims to compare the results with those obtained using solid fins over a range of Rayleigh numbers.Design/methodology/approachThe Darcy‐Brinkman equations were used to model the fluid flow inside the porous media and the Boussinesq approximation was used to model the buoyancy effect. The energy equation is also solved to find the temperature distribution in the domain of interest. The model equations are solved numerically using a finite volume code.FindingsPorous fins provided higher heat transfer rates than solid fins for similar configurations. This enhancement in heat transfer reached 75 per cent at Ra=5 × 104 and Da=2.5 × 10−2. It is also found that unlike solid fins the rate of heat transfer from the cylinder equipped with porous fins decreases with increasing the fin inclination angle.Research limitations/implicationsThe range of the Rayleigh number considered in this research covers only the laminar regime. The research does not cover turbulent flows. In addition to that, the local thermal equilibrium assumption is used.Practical implicationsThis work can help designers in selecting the proper material properties and operating conditions in designing porous fins to enhance the heat transfer in the annulus between two horizontal concentric cylinders under natural convection condition.Originality/valueThis work has not been done before and it can initiate additional research projects as looking at the performance of porous fins under other conditions and configurations (e.g. turbulent conditions).

Heat Transfer in a Porous Radial Fin: Analysis of Numerically Obtained Solutions

“…Abu-Hijleh [12] analysed the effects of using permeable fins on the forced convection heat transfer from a horizontal cylinder. The results obtained were similar to results obtained as per Kiwan and Zeitoun [10] in terms of the permeable fins providing much higher heat transfer rates. To study radial fins, a combination of the Taylor transformation and finite difference approximation was implemented by Yu and Chen [13,14].…”

“…He further discovered that, by choosing a precise value for the thermal conductivity ratio and the fin length to thickness ratio, the performance of the porous fin exceeded the performance of the solid fin. A study was conducted by Kiwan and Zeitoun [10] to test the performance of rectangular porous fins mounted around the inner cylinder of a cylindrical annulus by performing a finite volume type numerical study. It was concluded that, in comparison to solid fins, porous fins provided higher transfer rates for similar configurations and that the heat transfer rate from the cylinder equipped with porous fins decreased as the fin inclination increased.…”

Mixed Convection Heat Transfer in the Annulus Between Two Concentric Vertical Cylinders Using Porous Layers

“…In order to verify the numerical code, the results of the present code are tested and compared with the results obtained by Kiwan and Zeitoun (2007). The mixed convection in rectangular cavity with moving isothermal sidewalls and constant flux heat source on the bottom is solved numerically.…”

“…They presented the values of the critical thermal conductivity ratio for different flow cases. The effect of attaching two porous fins on the inner cylinder in the annuli between two horizontal concentric cylinders was studied by Kiwan and Zeitoun (2007). They found that the heat transfer using porous fins is enhanced when compared with that of solid fins.…”

Thermal performance of porous fins with temperature-dependent heat generation via the homotopy perturbation method and collocation method

“…The fin is porous to allow the flow of infiltrating through it. Extensive research has been done in this area and many references are available, especially for heat transfer in porous fins [1][2][3][4][5]. Described below are a few papers relevant to the study described herein.…”