Thermal–hydraulic characteristics and structure optimization of Z-channel printed circuit heat exchanger

Printed circuit heat exchanger (PCHE) is a compact equipment, which has the characteristic of high heat exchange efficiency. In practical application, the Z-type microchannel PCHE has shown unique advantage, and its structural parameters, such as pitch angle, pitch length, and channel diameter, have significant impact on its thermal–hydraulic characteristics. In this study, a series of PCHE models with a pitch angle of 5° to 45°, a pitch length of 12.3 mm to 24.6 mm, and a channel diameter of 1.25 mm to 2.25 mm are built by numerical method. Using a working medium of helium, we in detail analyze effects of these structural parameters of the PCHE on the related thermal–hydraulic characteristics. More importantly, to obtain the optimized structure of the PCHE, the response surface analysis of the simulation data is present. It shows that both the pitch angle and the inlet Reynolds number have greater effects on the flow and heat transfer performance of the PCHE. The quadratic polynomials of Nu and f are fitted by DesignExpert and the genetic algorithm is used for the multiobjective optimization. Three sets of optimized structures are given and also verified by the numerical simulations. The study could provide a guidance for the design and application of the PCHE in related engineering.