Numerical study of thermal-hydraulic performance of sCO₂-molten salt printed circuit heat exchanger with discontinuous fins channel

Printed circuit heat exchanger (PCHE) is an essential part of supercritical CO2 (sCO2) Brayton cycle in the 3rd generation of concentrating solar power plant. Molten salt and sCO2 as the heat transfer fluid in PCHE, it is of great significance to improve its thermal and hydraulic performance. To reach this goal, two new discontinuous fin channels of PCHE were designed and their thermal-hydraulic performance was studied by numerical simulation. The results show that the second discontinuous fins channel with the best comprehensive thermal-hydraulic performance for sCO2, which has the Colburn j factor improvement by 2.1-4.6% and the Fanning friction factor f reduction by 3.8-6.4% compared with that of the airfoil fins; While the third discontinuous fins channel has the best hydraulic performance for both the heat transfer medium of molten salt and sCO2, among which the pressure drop per unit length and f have the largest reduction by 0.05-24.7% and 5.91-19.1% for sCO2, and by 25.62-29.39% and 1.35-2.4% for molten salt. As a result, the second and third discontinuous fins channel of PCHE are proposed to sCO2 and molten salt, respectively, which can contribute to design the PCHE for the 3rd generation of solar thermal power generation.