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, θmax, Nu) as a function of Ra and other nondimensional parameters (A=H/L, B=1/L, F=d/L, kr). 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.