板翅式换热器封头内部流场的测量与改进研究

利用粒子图像测速仪（PIV），对板翅式换热器封头结构改进前、后的流场进行了可视化研究分析．实验结果表明，原始封头内部的物流分配存在严重的不均匀性，采用添加打孔挡板之后的改进型封头，流场的不均匀性有了很大的改善．从实验对比分析中得出，当挡板小孔呈错排分布、开孔率沿挡板的中轴线向两侧逐渐增加、且总开孔率达到509／6左右的时候，在相同的入口条件下，不均匀系数由原始封头的1．210降至0．209，最大流速与最小流速之比由23．163降至1．756．此研究结果对于板翅式换热器的优化设计具有重要意义．

Particle Image Velocimetry Experimental Investigation of Header Configuration on Flow Maldistribution in Plate-Fin Heat Exchanger

Flow characteristics of flow field in the header of a plate-fin heat exchanger were investigated with particle image velocimetry(PIV).It is found that the fluid flow maldistribution is very serious for conventional header while the improved header configuration with punched baffle can effectively improve the performance.When the punched baffle is proper in length,the small holes are in staggered arrangement and the punched ratio gradually increases from the central axis to the boundary along the baffle length,the performance of flow distribution in the plate-fin heat exchanger is effectively improved by the optimum design of header configuration.The flow maldistribution parameter S decreases from 1.210 to 0.209 and the ratio of the maximum velocity to the minimum decreases from 23.163 to 1.756.