Effects of azimuthal baffles on the heat transfer across a horizontal porous annulus

Numerical results are presented for natural convection in a horizontal porous annulus (pipe insulation) with azimuthal baffles. It has been shown that azimuthal baffles are effective in reducing convective heat losses from pipe insulation. The effectiveness in the reduction of heat loss depends on the baffle angular extent. For the cases examined in this study, the baffles with a full angular span (i.e., delta = 360 deg) give the best result. This implies that applying multiple layers of insulation separated by impermeable partitions is more effective than using a single layer of insulation with the same thickness.