并流多通道管壳式换热器壳程传热性能

对并流多通道进出口(MPC)轴流管壳式换热器壳程传热性能进行数值模拟,分别研究了管排数N,Re,不同开孔率的挡板对壳程进口段的局部传热系数分布、局部平均Nu的分布、换热器的平均Nu等特性的影响。结果表明:在无挡板条件下,随着N的减小,壳程传热系数分布不均现象得到有效的遏制,N=7时基本上无传热死区。挡板的存在,不但使得进口段的局部传热系数分布更加均匀,而且能够提高换热器的整体传热Nu。不同参数的挡板之间,挡板1的作用最为明显,可以使得Nu提高10%—12%。

Shell-side heat transfer performances of shell-and-tube heat exchanger with multi-parallel-channel

Shell-side heat transfer performances of inlet and outlet of longitudinal flow shell-and-tube heat exchanger with multi-parallel-channel(MPC) were numerically simulated.The influences of baffle on the local heat transfer coefficient distribution of inlet region,local-mean Nu distributions,and mean Nu of heat exchanger were investigated with pipe-line-number,N,Re and different punching ratio,respectively.The results reveal that with the decreasing of N,the non-uniformity of local heat transfer coefficient is effectively improved and there is not any heat transfer skip area when N=7.It also shows that fluid-distribution-baffles(FDBs) can not only effectively improve the local heat transfer coefficient distribution of inlet region but also enhance the global Nu of heat exchanger.The comparison of different FDBs shows that FDB of No.1 has the best performance and can enhance Nu by 10%—12%.