Prediction of flow maldistribution in printed circuit heat exchanger

Abstract

The printed circuit heat exchanger (PCHE) is widely used in a variety of extremely high temperature and high pressure applications. Since the PCHE is a typical multi-channel heat exchanger, the flow maldistribution may happen in the PCHE channels. In this paper, a new mathematical model is established to predict the flow maldistribution in a PCHE and it demonstrates that the traditional simplified numerical model with shortened heat transfer channels has a large error in predicting the flow maldistribution of a PCHE. Inlet and outlet local hydraulic losses are essential reasons to affect the flow maldistribution. An increase in the channel length improves the flow uniformity, while the flow uniformity becomes worse when the flow rate increases. When the channel length exceeds 500 times the hydraulic diameter of channel, the flow non-uniformity can be neglected at 0.12 kg/s. When the Reynolds number is smaller than 392, the flow non-uniformity can be neglected at the channel length of 0.1 m. Finally, with the aim of helping engineers make a quick judgement whether the flow maldistribution in a PCHE needs to consider or not, the relationship between the geometrical dimensions and operating conditions of a PCHE is proposed.