Thermal performance of integration between semi-circular channels and connecting pipes in PCHE employed for SCO₂ Brayton cycle

A semi-circular channel with connecting pipes is proposed to improve the overall heat transfer performance of the Printed Circuit Heat Exchanger (P CHE) used in the regenerator of the SCO₂ Brayton cycle. Two semi-circular channels at the top and bottom, which are horizontally placed, were filled with hot and cold CO₂, respectively. Thermophysical properties of SCO₂ were solved by integrating NIST into the FLUENT 2020. A mesh number of 5.0M and the SST k-ω turbulence model were selected via comparison with experimental data. As results show, the overall heat transfer performance of the semi-circular channel with connecting pipes is improved by 1.1-2.5 times. The vortex structure induced by the connecting pipes increases turbulent kinetic energy and further enhances the heat transfer. This indicates that the connecting pipe proposed in this study is beneficial to activate heat transfer and reduce flow resistance.