Comparative study on flow and heat transfer characteristics of sinusoidal and zigzag channel printed circuit heat exchangers

Printed circuit heat exchangers（PCHEs） are promising candidates for recuperators in supercritical CO2 Brayton cycles. A comparative study is given in this paper on the flow and heat transfer characteristics of PCHEs with sinusoidal and zigzag channels. With mass flow rates of 0.6–1.8 kg/h and the bend angles of 15°–30°, the thermal-hydraulic performance of the PCHEs is discussed. Results show that the sinusoidal channel is superior to the zigzag channel in its comprehensive performance. Larger bend angles result in greater reductions in pressure drop if sinusoidal channels are used instead of zigzag channels and a maximum of 48.4% reduction can be obtained in the considered working conditions. Meanwhile, the inlet sections should be carefully optimized since these sections account for up to 31% and 17% of the total pressure drop in the sinusoidal and zigzag channels, respectively. The corner shape of the zigzag channel can be specially designed to further reduce the pressure drop. The nonuniform density and heat flux distributions in both channels are found to be related to the periodic changes of flow directions and the centrifugal forces should not be ignored when optimizing the sinusoidal and zigzag channels.