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.

Acknowledgments

This work was supported by National Natural Science Foundation of China (Grant No.52076006) and the Inner Mongolia Science and Technology Major Project (Grant No. 2021ZD0036).

Additional information

Notes on contributors

Yanchun Yang

Yanchun Yang is Doctoral student at Beijing University of Technology. Beijing, China. Her research interests are solar thermal power generation.

Yuanwei Lu

Yuanwei Lu is a Professor at Beijing University of Technology, Beijing, China. Her research interests are heat transfer enhancement mechanism of molten salt in high temperature heat storage, energy saving and renewable energy utilization.

Yuting Wu

Yuting Wu is a Professor at Beijing University of Technology, Beijing, China. His research interests include heat transfer and storage, renewable energy technologies such as solar and geothermal energy, and power generation.