Brazed plate heat exchangers, single phase, flow distribution
This paper presents a mathematical model to predict single-phase flow distribution in brazed plate heat exchangers (BPHEs). In this model, the flow distribution among parallel channels is predicted by imposing the condition that each flow path in the heat exchanger has an identical total pressure drop. The model has been validated by the experiments, in which the pressure drop of gas flow in the headers, as well as across the channels is measured. This model is then used to explore the effect of maldistribution on the thermal performance of the heat exchangers. The experimental and modeling results show that, for a U-type BPHE, the channel mass flow rate generally decreases along the flow direction in the inlet header. The single-phase maldistribution is highly depending on the relative magnitude of the pressure change along the headers and the pressure drop through the plate channels. For given heat transfer area, a heat exchanger with a longer plate would benefit from less non-uniformity in mass and higher heat transfer coefficient, but suffer from higher overall pressure drop.