Effect of single-phase flow maldistribution on the thermal performance of brazed plate heat exchangers

Abstract

This paper presents an experimental and numerical investigation of the effect of single-phase flow maldistribution on the thermal performance of brazed plate heat exchangers (BPHEs). A thermal performance model of the BPHEs is developed with the consideration of flow maldistribution among the channels. The proposed model is validated against the experimental results. The model simulations reveal that the flow maldistribution has a trivial impact on the overall thermal capacity of the BPHEs if two fluid streams are supplied from the same side of the heat exchangers; if two fluid streams are supplied from the opposite side, the overall thermal performance is significantly deteriorated due to mismatched flow distributions of two fluid streams. Moreover, other factors are also proven to act in this issue, including the number of plates, plate length, header/port size, sudden expansion flow at the heat exchanger entrance, and heat capacity rate ratio of two streams. They either directly change the flow distribution or potentially affect the thermal effectiveness of the BPHEs. Based on the simulation results, correlations are generated, which can evaluate the thermal capacity degradation due to flow maldistribution without the necessity of knowing the detailed flow distribution and building heat exchanger models.