基于螺旋片强化的套管换热器性能

Performance of double-pipe heat exchanger enhanced by helical fins

基于RNGκ-ε模型对螺旋片强化的套管换热器的传热进行模拟，通过模拟结果与文献中的实验结果进行对比来验证模拟的可行性；分析了Reynolds数为2362-16860范围内的螺旋升角α变化对Nusselt数和摩擦阻力系数f的影响；并考察了等泵功率下的综合传热性能PEC值的变化规律。结果表明：Nu和f的平均误差分别为7．1％和1．3％，证明所采用的研究方法是可行的；α在15°～75°范围内，Nu和f均随着α的减小而增大，特别地，当α小于35°时，f随α的减小剧烈增大；在等泵功率下，PEC值为0．84～1．93；α在15°～45°时，α为35°具有较好的综合传热性能，α为55°、65°和75°时，虽然其PEC值比35°时略高，但其Nu与35°时相比要小很多，实际应用中考虑到传热速率的问题，选择35。的螺旋升角较为合适，此时，PEC值为1．26～1．62。另外，为减小f,提出倾斜螺旋片强化的方法；螺旋升角α为35°、螺旋片倾斜角β为10°时，与普通螺旋片相比，Nu基本一致，甚至略大，而厂减小了12．5％～14．5％，此时，PEC值为1-38～1．71；场协同理论也很好地验证了这一结果。

In this paper, RiNG κ-ε model is used to simulate the heat transfer of a double-pipe heat exchanger enhanced by helical fins. The simulation results are verified with experimental results. With the Reynolds number from 2362 to 16860, the effect of helix angle α on the Nusselt number and frictional resistance coefficient fare analyzed. The change of performance evaluation criteria（PEC） value and the comprehensive heat transfer performance at the same pump power are examined. The average error of Nu and f are 7.1% and 1.3%, respectively, indicating that the method used is appropriate. For α from 15° to 75°, both Nu and f increase asα decreases. In particular, for α values less than 35°, f increases dramatically as a decreases. With the same pump power, the value of PEC varies from 0.84 to 1.93. In the α range from 15° to 45°, the comprehensive heat transfer performance is better with 35°. Although the PEC values with α of 55°, 65° and 75° are slightly higher than that of 35°, Nu is much smaller. Considering the rate of heat transfer in applications, helix angle of 35° is more appropriate, with PEC of 1.26--1.62. Besides, it is proposed to use oblique helical fins to reduce the value off Compared with double-pipe heat exchanger enhanced by common helical fins, the Nu value of that enhanced by oblique helical fins with α of 35° and fl of 10° is a little higher, f is reduced by 12.5%--14.5%, and PEC variesfrom 1.38-1.71. The field synergy principle also verifies the result.