Boundary condition dependent natural convection in a rectangular pool with internal heat sources

This paper presents results of steady-state experiments concerned with natural convection heat transfer of air in a rectangular pool in terms of the Nusselt number (Nu) versus the modified Rayleigh number (Ra') varying from 10(9) to 10(12). Cartridge heaters were immersed in the working fluid to simulate uniform volumetric heat generation. Two types of boundary conditions were adopted in the test: (1) top cooled, and (H) top and bottom cooled. The other sides were kept insulated. In the case of boundary condition II, the upward heat transfer ratio, (N over dot u(up)/(Nu(up)+Nu(dn)), turned out to be 0.7-0.8 in the range of Ra' between 1.05 x 10(10) and 3.68 x 10(11).