Heat transfer and flow characteristics of straight-type PCHEs with rectangular channels of different widths

Abstract

Printed circuit heat exchanger (PCHE) is considered to be the most promising heat exchangers in the supercritical CO2 Brayton cycle. The heat transfer and flow characteristics in straight-type PCHEs with rectangular channels of different widths were numerically investigated in this paper. With the increase of rectangular channel width, the average heat transfer coefficients in the cold side decrease first and then increase, while the average heat transfer coefficients in the hot side always increase. The increase of rectangular channel width can effectively increase the heat transfer rate per unit volume and reduce the pressure drop at the same mass flux. However, the changes of heat transfer rate per unit volume and pressure drop tend to be gentle with the width increase. Furthermore, the overall performance evaluation of PCHEs with rectangular channels of different widths was performed. The overall performance evaluations of rectangular channels in the hot side of PCHEs are enhanced compared with the semicircular channel, and the enhancement becomes more and more significant with the increase of mass flux. While the overall performance evaluations of the rectangular channels in the cold side are not as good as that of the semicircular channel. The channel width should be appropriately increased in the hot channel design of straight-type PCHEs to reduce flow resistance and improve overall performance evaluation. The sharp corners of the PCHE channel cross-sections should be eliminated to reduce the heat transfer deterioration zone.