并流多通道管壳式换热器壳程流场分布比较

摘要

优化壳程流场分布和减少压降对并流多通道进出口结构(MPC)轴流管壳式换热器具有非常重要的作用。分别采用商用CFD软件FLUENT 6.3和皮托管测速方法对MPC换热器壳程流场分布与阻力性能进行数值模拟与实验研究，分别研究了管排数N、Re、不同开孔率的挡板对壳程流场分布、阻力性能的变化规律。结果表明：(1)无挡板时，随着N的减小，壳程流场分布不均现象得到有效的遏制，压降大幅降低，最大降幅达到70％以上；(2)挡板能够有效促进流场的二次分布，但亦使得阻力增大较为显著；(3)比较不同挡板，挡板1的效果最优；(4)换热器压降主要在进出口段产生。%　　In order to solve the problems of the longitudinal flow shell-and-tube heat exchanger such as fluid flow maldistribution, high pressure drop and the overall performance deterioration, a novel structure of multi-parallel-channel inlet/outlet (MPC) was proposed. The numerical and experimental investigation on shell-side fluid flow distribution and resistance performances of the MPC heat exchanger were carried out by employing commercial CFD software of FLUENT 6.3 and Pitot tube velocimetry, respectively. Under the conditions of without FDBs (Fluid Destribute Baffles) and with FDBs of different punching ratioes, both shell-side fluid flow distribution and resistance performances were investigated under different Reynolds numbers (Re) and numbers of tube row (N) respectively. Investigation results show as follows: (1) Under the condition of without FDBs, with the decrease of N, the maldistribution of shell-side is effectively improved and the resistance performances can be reduced sharply, even more than 70%of total pressure drop can be reduced at same Re when N=11 decreases to N=7; (2) FDBs could effectively improve the shell-side fluid maldistribution, but the pressure drop will increase at the same time. (3) Comparison of different FDBs shows that the FDBs of No.1 has the best performances of fluid flow distribution at the same Re and N;(4) The main pressure drop of shell-side are generated in the region of inlet and outlet of the heat exchanger.