Single-phase flow distribution in plate heat exchangers: experiments and models
Abstract Maldistribution of fluid among parallel channels is one of the main issues in applications of plate heat exchangers. This paper presents an experimental and numerical investigation of the single-phase flow distribution in the brazed plate heat exchangers, but the results can be applied to plate-and-frame and plate-and-shell designs. In the experiments, the pressure profile in the heat exchanger is measured by the probes inserted into the headers. The flow distribution is determined by the measured pressure drop across the channels and the developed in-channel friction factor correlation. The experimental results indicate that in a U-type brazed plate heat exchanger, the channel flow rate first increases for the first several channels near the heat exchanger entrance due to the sudden expansion of flow in the inlet header. For the rest channels, the flow rate decreases with the distance away from the entrance/exit of the heat exchanger. Such a distribution profile is associated with the axial momentum transfer in the inlet header. The influence of the total flow rate on the distribution profile is trivial, but the maldistribution is more severe with an increased number of plates. Two distribution models presented are developed based on the principle of equal total pressure drop for all flow paths. Two models calculate the pressure profile in the headers by 3-D CFD modeling and 1-D mass and momentum conservation equation. The experimental results validate the models.