Abstract: Four fan-shaped baffles are used to form a pitch in shell side of heat exchangers with helical baffles. There are two triangular leakage zones between the two adjacent baffles, making the shell-side fluid deviate from ideal plug flow and degrading the heat transfer performance of the heat exchanger. In this paper, the structure of fold baffle is used to block the external triangular leakage zones, so the shell-side fluid flows in approximately continuous spiral flow. The heat transfer experiments are used to evaluate the performance of the improved heat exchanger. The experimental results show that the shell-side heat transfer coefficient is increased by 11.6%-21.6% and the overall heat transfer coefficient is increased by 6.7%-19.1% with an average value of 16.9%, compared with that of conventional heat exchanger with plain baffles. The heat transfer of improved heat exchanger is intensified obviously. Although the shell-side pressure drop increases correspondingly, the increment in pumping power consumption is limited. The values of thermal performance factor are all above 1.0, with an average value of 1.071. It demonstrates that taking into account heat transfer coefficient and pressure drop, better integrative performance is obtained through the configuration optimization of baffles. It is benefit to optimizing design for heat exchangers with helical baffles.

Key words: heat exchanger with helical baffles, heat transfer, optimization, fold baffle, triangular leakage zone, experimental validation

摘要： 目前普遍使用的螺旋折流板换热器壳程的一个螺距主要采用4块平面折流板结构，但在相邻两块折流板的直边搭接处存在顶角相对的两个三角漏流区，使壳程流体偏离理想的螺旋流，严重影响了换热器的性能。采用折面折流板结构，可以封闭原始折流板之间的外侧三角漏流区，使壳程流体更接近连续的螺旋流动。实验结果表明，采用折面折流板代替原始的平面折流板后，换热器总传热系数增加6.7%～19.1%，平均增大16.9%，表明此折面折流板能有效提高螺旋折流板换热器的换热性能。虽然壳程压降也随之增大，但带来的泵耗功率增量非常有限。换热器的热性能因子均大于1.0，平均值为1.071，表明结构改进后的换热器，其综合性能平均提高7.1%。基于实验数据，拟合了结构改进前后的换热器壳程传热系数和阻力系数的相关实验关联式。研究结果对于换热器的节能优化具有重要的指导意义。

关键词: 螺旋折流板换热器, 传热, 优化, 折面板, 三角漏流区, 实验验证