Numerical investigation on the Thermal-hydraulic performance of the modified channel supercritical CO2 printed circuit heat exchanger

•Flow and heat transfer in modified channels, zigzag channels and straight channel are studied using CFD.•The numerical code is validated with published experimental data and simulation results.•Comparisons on local and overall thermal–hydraulic performance among 13 different cases are made respectively.•Optimum modified channel configuration with the best comprehensive performance is suggested. Printed circuit heat exchangers (PCHE) are designed to improve heat recovery and energy saving in supercritical CO2 (S-CO2) power cycles. In the current study, a modified channel PCHE is proposed based on the regular straight channel and a zigzag channel. The thermal–hydraulic performance of four different types of PCHE is numerically investigated and the methods are verified by both experimental and numerical results. The numerical results are presented for a Reynolds number based on the inlet conditions between 5 000 and 25 000. From the numerical results, the local pressure loss and local heat transfer coefficients are analyzed and discussed. Subsequently, the global Nusselt number and Fanning friction coefficients are discussed. It is found that the inserted straight section contributes to uniform flow, resulted in significant pressure loss reduction with a slight decrease in heat transfer. The modified channel can reduce the Fanning friction coefficient by 33.1%-84.7% while the global Nusselt number reduction is about 3.6%-30.3%. This leads to a maximum performance evaluation criterion (PEC) enhancement of 45.9%.