Convective heat transfer of molten salt outside the tube bundle of heat exchanger

Experimental measurements and theoretical analyses were conducted to investigate the convective heat transfer of ternary nitrate salt outside the tube bundle of heat exchanger. Various experiments were performed within the range of Reynolds number 400-2300 and fluid temperature 250-400 °C. In general, Nusselt number of molten salt flow outside the tube bundle increased with Reynolds number rising and fluid temperature dropping. Because of the tube bundle structure, Nusselt number of molten salt flow outside the tube bundle was evidently higher than that of fluid in smooth tube. As the fluid temperature decreased, the heat transfer coefficient obviously rose with the increase of Prandtl number and viscosity ratio caused by heat transfer temperature difference. By optimizing the exponent of Reynolds number, the experimental heat transfer correlation of molten salt flow was proposed by considering the cooling effect, and it very well fit with experimental data with maximum deviation of 15.1%.