A Numerical Study of Effect of Natural Convection on Thermal Properties of Horizontal Oriented Porous Insulation

Abstract

This paper deals with numerical computations carried out to predict the effect of natural convection on the thermal performance of porous material. The effect of natural convection in a horizontal porous layer on heat transfer will be discussed. The study of this configuration is essential to understanding the performance of insulation of the type commonly used in roofs and attics. The influence of natural convection on the global heat transfer rate for mineral wool, loose-fill and insulation made of small and large polystyrene balls was studied. The results are presented in terms of dimensionless Nusselt and Rayleigh numbers as a function of temperature difference across the insulation. The temperature distribution across the insulation are also plotted.

Keywords

porous medium permeability natural convection numerical simulation CFD

Get full access to this article

View all access options for this article.

References

Davidson, L. and B. Farhanieh , 1992. CALC-BFC: Afinite-volume code employing collocated variable arrangement and Cartesian velocity components for computation of fluid flow and heat transfer in complex three-dimensional geometries, Rept., Dept. of Applied Thermodynamics and Fluid Mechanics, Chalmers University of Technology, Gothenburg, Sweden.

Delmas, A. A. and K. E. Wilkes . 1991. Numerical analysis of heat transfer by conduction and natural convection in loose-fill fiber-glass insulation—Effects of convection on thermal performance, Rept., Oak Ridge National Laboratory, Oak Ridge, TN.

Nield, D. A. and A. Bejan . 1992. Convection in Porous Media, Springer-Verlag, New York.

Patankar, S. V. 1980. Numerical Heat Transfer and Fluid Flow, McGraw-Hill, Washington.

Rhie, C. M. and W. L. Chow . 1984. Numerical study of the turbulent flow past an airfoil with trailing edge separation, AIAA J., 21, pp. 1527–1532.

Serkitjis, M. 1995. Natural convection heat transfer in a horizontal thermal insulation layer underlaying an air layer. P-95:2, Ph. D. Thesis, CTH, Building Physics, Gothenburg, Sweden.

Shankar, V. and C.-E. Hagentoft . 2000. Numerical Investigation of Natural Convection in Horizontal Porous Media Heated from Below—Comparisons with Experiments, J. Thermal Env. and Bldg. Sci., Vol. 23, pp. 318–338.

Versteeg, H. K. and W. Malalasekera . 1988. An Introduction to Computational Fluid Dynamics, the Finite Volume Method, Longman, England.