Improving effectiveness of pipe insulation by using radial baffles to suppress natural convection

Abstract

In this paper, the feasibility of using radial baffles to improve the effectiveness of pipe insulation is investigated numerically. Three baffle designs have been considered, i.e. full baffles, partial inner baffles and partial outer baffles. These designs have been applied to the case of horizontal pipe insulation. Calculations have covered a range of Rayleigh numbers of practical interest (i.e. 50 ⩽ Ra ⩽ 500). In addition, the relations between the heat loss and the baffle orientation angle is carefully examined for each pipe-baffle configuration. The results show that radial baffles are effective to suppress the natural convection that arises in a pipe insulation. The effectiveness increases with the baffle number. It has also shown that partial baffles work better than full baffles. At a high Rayleigh number ( Ra = 500), the flow and temperature fields at some orientation angles become unstable. The averaged heat transfer, however, is still less when using baffles.