Investigation on the effects of narrowed channel cross-sections on the heat transfer performance of a wavy-channeled PCHE

•The performance of PCHE is improved by narrowing the channel cross section.•The empirical correlations based on periodical channel sections perform very well.•The distributional patterns of heat flux around channel surfaces are revealed. The printed circuit heat exchanger will play an important role in the field of advanced supercritical carbon dioxide cycle in the future because of its high thermal-hydraulic performance and structural rigidity. In this study, the heat transfer characteristics of a wavy channeled PCHE are numerically investigated and the effects of narrowing channel cross sections on the thermal-hydraulic performance are analyzed. The results show that the heat flux distribution around the channel surface varies periodically and there exist three banded regions with low heat flux for each period, one on the arched surface and two on bottom surface. Narrowing the channel cross section will increase the heat transfer rate per unit volume, making the PCHEs more compact and economic. New empirical correlations of heat transfer and frictional factor are put forward based on the fluid parameters of each period of the channel, and heat transfer correlation can predict the Nusselt number of the PCHE very well with 10% error.