Numerical simulation on the hydraulic performance and performance evaluation on heat thransfer of brazed plate heat exchangers with two-phase flow maldistribution

Abstract

The thermal performance of brazed plate heat exchangers (BPHEs) can be affected by flow maldistribution. In this study, a numerical model with porous media is established to predict the flow distribution of plate heat exchangers (PHEs), and the ε-NTU method was employed to evaluate the heat transfer efficiency of the PHE. It’s found that the flow maldistribution in PHE is serious, and there is an obvious difference between the velocity distribution and the mass flow distribution in the two-phase flow due to phase separation. To improve flow uniformity, orifice tube distributor (OTD) with baffles and groove type distributor (GTD) have been proposed and studied at different qualities. It turns out that quality has a great influence on nonuniformity. With the increase of quality, the nonuniformity of baseline design and OTD increased first and then decreased, while GTD showed different performances. Both distributors can reduce flow nonuniformity compared with the baseline design. Due to the baffles hindering the backflow, the OTD shows excellent performance at different qualities, with a 62% reduction in flow nonuniformity and a 20.3% increase in heat transfer effectiveness. The performance of GTD is slightly inferior to OTD, with 42% reduction in flow nonuniformity and 17% improvement in heat transfer effectiveness.