Turbulent Free Convection Enhancement in Square Cavities Driven by Different Gas Mixtures

The present paper investigates a promising avenue for the intensification of turbulent free convection in square cavities using an adequate selection of binary gas mixtures. Five binary gas mixtures have considered helium (He) as the primary gas component and carbon dioxide (CO2), methane (CH4), nitrogen (N2), oxygen (O2), and xenon (Xe) the secondary gas components. In the thermodynamic context, the thermophysical properties viscosity, thermal conductivity, density, and isobaric heat capacity depend on three quantities: temperature, pressure, and molar gas composition. The finite volume method is the vehicle used to perform the numerical calculations of the enlarged set of conservation equations, wherein turbulence is modeled with a low-Reynolds k-s model. The turbulent velocity and temperature fields for each binary gas mixture and air were calculated at different locations in the cavity and presented in terms of streamlines and isotherms for Ra = 2 x 109. The results culminate with the allied convective coefficient km/B varying with the molar gas composition win the w domain [0,1] for each binary gas mixture. Values of the maximum allied convective coefficients hm max/B attained at the correlative optimal molar gas compositions w01, are easily extracted from a graphical display.