三个关键几何参数对人字形波纹钎焊板式换热器换热性能影响的分析

以水-水热交换器为例，以CFD模拟软件为手段，以κ-ε模型为基础构建人字形波纹板式换热器模型，并系统分析波纹倾角、波纹深度、波纹间距这3个重要几何参数对换热器内部温度场、压力场、流场及平均努塞尔数和流动阻力的影响。研究结果表明，触点是板间换热效果最好的点，触点的扰流作用使流体在触点周围湍流程度最高，传热得到强化，这也是板式换热器内流体在雷诺数较低时发生湍流的主要原因；另一方面，流体经过触点后压力损失较大，是产生阻力损失的主要原因。波纹倾角是最重要的一个影响参数，最优波纹倾角在60°附近，此时换热效果较好而阻力尚未达到最大；波纹深度增加，平均努塞尔数增大，换热效果趋于好转，板间压力降也逐渐降低。但随着波纹深度的增加，结垢的倾向也会增加，因此较为合理的波纹深度应该在4～5mm之间；在给定的边界条件下，通过计算所得的波纹间距与波纹深度之比在3～4范围内时换热器性能较好。

Study on the effect of three key geometric parameters of chevron corrugated brazed plate heat exchanger on the heat transfer performance

Based on the CFD Fluent software, builds a chevron corrugated plate heat exchanger model, and systematically analyzes the influence of three important parameters of geometry-corrugated angle, corrugated depth, corrugated spacing on the internal temperature field, pressure field, flow field, average Nusselt number and flow resistance on the water-water plate heat exchanger. The results show that the contact points are the best places for heat transfer between two heat exchanger plates and the disturbance of con- tact points make the strongest turbulences around the contact points, which is the main reason that the fluid turbulence occurs at lower Renault number for the plate heat ex- changer and the heat transfer is enhanced. On the other hand, a greater pressure loss occurs after the fluid passes by the contact point, which is the main part of total pressure loss in the plate heat exchanger. Among the three geometric parameters, corrugated angle is the most important one and the best corrugated angle is about 60° with a good heat transfer effect and a moderate flow resistance. The average Nusselt number increases as the corrugated depth increases which enhances the heat transfer with a decreased pressure loss but is apt to scale, thus a corrugated depth of 4~5 mm is appropriate. It is also found that a ratio of the corrugated spacing to the corrugated depth of 344 is appropriate at the specified boundary condition.