Investigation of flow patterns in the entrance of heat exchanger by PIV technology

To improve the uniformity of fluid distribution in plate-fin heat exchanger, flow characteristics of flow field in the header were investigated by Particle Image Velocimetry (PIV). The velocity fields were measured using the two-frame cross-correlation technique. A series of velocity vector and streamline graphs of different cross-sections were achieved in the experiments. The results indicate that the improved header with punched baffle can effectively improve the performance of fluid flow distribution in the header. The global flow maldistribution parameters in plate-fin heat exchanger is reduced from 1.210 to 0.209, and the ratio of the maximum velocity to the minimum is reduced from 23.163 to 1.756 by installing the punched baffle. The results validate that PIV is well suitable to investigate complex flow pattern, and the conclusion is of great significance in the optimum design of plate-fin heat exchanger.