Study on heat transfer characteristics of supercritical co2 printed circuit heat exchangers with different shape channels

Abstract

Printed circuit heat exchanger (PCHE) is a microchannel heat exchanger. Because of its high efficiency, high pressure and high temperature resistance, it has been widely used in photovoltaic power generation, nuclear energy and other fields. In particular, the research on the cross section shape of heat exchanger channel has been widely concerned by researchers. In this paper, the PCHE performance of semi-circular, square and trapezoidal channels with the same inlet and outlet area is compared under the pressure of 8MPa. The heat transfer performance of the mass flow rate in the range of 500-2000 kg /(m2) under three cross section shapes was investigated. The results show that the heat transfer effect of fluid in the trapezoidal channel is obviously better than the other two channels. This is mainly because the heat exchange contact area of cold and hot fluids in the trapezoidal channel is large, resulting in an increase in heat exchange between cold and hot fluids. When the inlet velocity is the same, the Reynolds number of the fluid in the trapezoidal channel is larger. The outlet temperature of the cold fluid in the trapezoidal channel is 7.9% higher than that in the semi-circular channel and 4.1% higher than that in the rectangular channel. The outlet temperature of the hot fluid in the trapezoidal channel is 6.28% lower than that in the semi-circular interface channel and 3.4% lower than that in the square channel. The trapezoidal channel has better PCHE heat transfer effect and better heat transfer performance.