阻流板对1/4螺旋折流板换热器综合性能的影响

Impact of block plates on comprehensive performance for heat exchangers with quarter helical baffles

建立存在三角区和阻流板堵住三角区2种1/4螺旋折流板换热器模型;采用大型CFD分析软件FLUENT借助数值模拟的方法,研究阻流板对换热器壳侧流动与传热性能的影响;并对阻流板结构进行了优化分析。结果表明:增加阻流板能够有效地提高换热器的壳程传热性能,但壳程压降也随之增加。小螺旋角时,增加阻流板使换热器的综合性能降低;当螺旋角增大到一定程度,阻流板增加后换热器综合性增加;阻流板完全堵住三角区时,换热器壳程传热系数最大,同时壳程压力损失也最高。螺旋角为15°,阻流板长度为5r/8时,较无阻流板时换热器综合性能基本相同,壳程传热系数增加7.5%—8.5%。计算结果为改进螺旋折流板换热器折流板结构、优化折流板间三角区、强化换热器传热等方面提供了理论依据。

The models of quarter helical baffles heat exchanger with triangle and plates-blocked triangle were established. With large CFD analysis software Fluent,the flow and heat transfer performances of heat exchanger with block plates were investigated with numerical simulation,and the structure of block plates was optimized. The results show that blocked triangle effectively increases the heat transfer performance of shell side,but pressure drop increases accordingly. When helix angle is smaller,the comprehensive performance of heat exchanger with blocked plates decreases; when helix angle increases to an extent,the comprehensive performance of heat exchanger increases; when triangle area is completely blocked,both heat transfer coefficient and pressure drop of shell side are the highest. Compared to non-blocked plates,when helix angle is 15° and length of blocked plates is 5r /8,the comprehensive performance is basically the same,and the heat transfer coefficient increases from 7. 5% to 8. 5%.The results provide the theoretical basis for improvement of structure,optimization of triangle area between baffles,and enhancement of heat transfer,etc.