Thermal performance analysis of molten salt based on a novel experimental rig

Abstract

In the field of medium and high temperature solar heat utilization, molten salt is widely used. Besides, the thermal performance of molten salt is very important for solar heat utilization. However, current studies were mainly conducted by simulation, supplemented by experiment. Therefore, a novel experimental rig was designed and established, in order to investigate the performance of commercial molten salt in the typical heat transfer process. The tests under 24 conditions were conducted. Gnielinski empirical formula was modified by experiments to describe the thermal performance of molten salt more accurately. 400 groups of randomized tests with different heat exchangers were carried out to confirm the application conditions and accuracy of the modified empirical formula. The average relative deviation between the experimental and the calculated comprehensive heat transfer coefficient was 3.09% in the molten salt -oil double-pipe heat exchanger, and was 3.42% in the molten salt -oil 1–1 tube-shell heat exchanger. The research result could provide theoretical and experimental support for thermal performance analysis of molten salt. This modified empirical formula with wider range of utilization conditions could accurately describe the thermal performance of molten salt in common commercial heat exchangers of practical engineering.