Natural Convection and Conduction in Porous Wall, Solar Collector Systems Without Vents

Steady natural convection heat transfer has been studied in porous wall, solar collector systems. The boundary conditions were: two isothermal walls at different temperatures, two horizontal bounding adiabatic walls, and either uniform or nonuniform heat generating porous layer without vents. The aspect ratio A was from 0.5 to 1.4. The Rayleigh number varied from 10³ to 10⁸. The Darcy number was from 10⁻⁸ to 10⁻² but the detailed studies were carried out only for 10⁻⁴, an optimum value. The results are presented in terms of thermal parameters (θ, θ_max, Nu) as a function of Ra and other nondimensional parameters (A=H/L, B=1/L, F=d/L, k_r). The isotherms and streamlines within the system are also produced. The overall results indicate that geometrical parameters are the most important parameters affecting the system performance.