Constructal design of double-layer asymmetric flower baffles

Abstract

Shell and tube heat exchangers are one type of industrial equipment used widely, which have significant impacts on energy conservation and emission reduction. Developing and optimizing new baffles is an important way to improve the thermal-hydraulic performance of exchangers. This paper proposed a new double-layer asymmetric flower baffle, and the effects of the dislocation angle and asymmetric volume ratio of the baffles on the thermal-hydraulic performance of exchangers were investigated according to constructal design and by using the three-dimensional numerical simulation, i.e. in the case of the same fixed volume of baffles, compared with segmental baffles. The results show that compared with segmental baffles, the double-layer asymmetric flower baffles significantly improved the comprehensive thermal-hydraulic performance, i.e. heat transfer rate was reduced to 92% on average while the pressure drop was controlled at about 45%, therefore, the efficiency evaluation coefficient achieved an average improvement of 106%. The smaller the dislocation angle and asymmetric volume ratio, the larger the efficiency evaluation coefficient, the smallest dislocation angle and asymmetric volume ratio increased the efficiency evaluation coefficient by 72% and 22%, respectively, compared to their maximums. The new baffles and constructal design method proposed herein can provide theoretical guidance for improving the comprehensive thermal-hydraulic performance of shell and tube heat exchangers.