Experimental and numerical study on thermal performance of a fluoride salt-to-air heat exchanger

Highlights: • Fluoride salt-to-Air Heat Exchanger (FAHX) is constructed and tested. • Steady state heat transfer experiment for Fluoride salt heat exchanger is conducted. • The thermal performance of the Fluoride salt heat exchanger is studied numerically. • Simulation program for thermal performance of the FAHX is validated by experiments. In order to better understand the thermal performance of Fluoride salt-to-Air Heat Exchanger (FAHX), the heat transfer process of FAHX with multiple-tube banks staggered arrangement in a Fluoride-salt High Temperature Test Loop (FHTL) is studied experimentally and numerically. Results show that the temperature distribution obtained from CFD fit well with experiment measurements with a maximum deviation of 10%, which indicates that the CFD program is applicable. Then, the three-dimensional features of the FAHX in the tube-side and shell-side are analyzed. Results show that peripheral tube temperatures of the tube bundles are slightly lower than the center tubes, and all tubes temperature are obviously above the melting temperature of the fluoride-salt ∼454 °C, which implies that there will be less risk of fluoride-salt freezing in the FAHX. Finally, the heat transfer process related flow distributions are discussed, helpful guidance are proposed for the optimal design of the molten salt-to-air Heat exchanger.