Heat Transfer and Flow Friction Performance of Molten Salt and Supercritical CO2 in Printed Circuit Heat Exchanger

Abstract

Molten salt and supercritical CO2 (sCO2) have been selected as the two most promising heat transfer fluids in the 3rd generation of solar thermal power generation, so it is very important to study their heat transfer and flow characteristics for the design of heat exchanger. This research studies thermohydraulic performance of molten salt and sCO2 in a printed circuit heat exchanger (PCHE) with different channel configurations. A PCHE unit with straight channel for molten salt and discontinuous fin for sCO2 was selected for the fin shape optimization of sCO2 side. Results show that the newly proposed Fin II channel can reduce the flow resistance of sCO2 compared with the airfoil Fin I, and Fanning friction factor can be decreased by 11.93% at the expense of Colburn factor decreased by 2.24%. The mechanism of heat transfer enhancement is analyzed by using field synergy principle, and the results show that the temperature field, velocity field and pressure field have better synergy in the Fin II channel. The optimal finned channel improves the comprehensive performance of PCHE, which contributes to the third generation of solar thermal power generation.