NATURAL-CONVECTION IN A HORIZONTAL POROUS ANNULUS WITH MIXED TYPE OF RADIAL BAFFLES

The feasibility of using different combinations of inner and outer partial baffles to improve the effectiveness of pipe insulation is numerically investigated in this paper. Calculations have covered a range of Rayleigh numbers of practical interest, i.e., 50 less-than-or-equal-to Ra less-than-or-equal-to 500. For each baffle configuration, the relation between the heat loss and baffle orientation angle is also carefully examined. The results confirm the effectiveness of radial baffles in the supression of natural convection which may arise in a pipe insulation. Among the three cases studied, inner partial baffles give the best performance.