Numerical investigation of natural convection heat transfer in porous medium saturated with carbon dioxide in supercritical state

Abstract EN

Natural convection in a porous medium saturated with supercritical carbon dioxide (CO2) which is bounded by square cavity is studied numerically by solving the governing Darcy equation using finite-differences method.

The side walls of cavity were assumed to be isotherm with fixed temperature difference of 0.0152 K, while the upper and lower sides are assumed to be thermally insulated, the aspect ratio is chosen to be one, with cavity height of 0.01 m, the Darcy number adopted is 10-5, usually these values lead to very small modified Rayleigh number.

Despite all of this, the state of supercritical takes the fluid (CO2) to a huge changes in its properties (Cp, P, U, B) which allow to transfer a relatively large amount of heat between the hot and cold sides of the cavity with a very small temperature difference with maximum Nusselt number over 13 The results of this study show clearly these concepts.

The state of carbon dioxide in supercritical region is specified by reduced pressure re P re = P / P c and reduced temperature re a T re = Ta / T c, the reduced temperature and pressure have been varied as T re : 1.002 – 1.72, P er : 1.1 – 2.0.