Investigation on convection heat transfer performance of quaternary mixed molten salt based nanofluids in smooth tube

Abstract

As thermal energy storage and heat transfer material, molten salt is widely used in concentrating solar power (CSP) plant. The thermophysical properties of molten salt can be significantly changed by adding nanoparticles into molten salt. In this work, the heat transfer characteristics of quaternary mixed molten salt with SiO2 nanoparticles are experimentally studied. The results show that the heat transfer performance of molten salt based nanofluids is better than that of pure molten salt. The convection heat transfer coefficient and Nu number of molten salt based nanofluids are 22.34% and 11.42% higher than that of pure molten salt, respectively. The classical heat transfer correlation equations are not suitable for quaternary mixed molten salt based nanofluids. The heat transfer correlation of quaternary mixed molten salt based nanofluids is fitted, the maximum deviation between the experimental data and fitted heat transfer correlation of molten salt based nanofluids is 12%. This work could provide basic heat transfer data of molten salt based nanofluids for thermal energy storage application.