Investigation Of Turbulent Convective Heat Transfer Of Molten Salt Flow Inside A Single-Bend Circular Pipe

Abstract

This article investigates the coupled flow and heat transfer behavior of two different nitrate molten salts, i.e., Solar Salt, and Hitec, as they flow in a single-bend of 180 degrees horizontal circular pipe. The internal turbulent flow of these two salts is investigated to heat a part of a high-temperature heat exchanger which will be used in a sustainable thermochemical cycle for hydrogen production. Governing conditions for the high-temperature turbulent flow of molten salts are derived based on the previously published and thoroughly validated articles, applied on the geometry and boundary conditions of the single-bended pipe and then compared with well known, experimentally validated convective heat transfer correlations. This research shows that the bend causes an intense mixing in the flow due to separation. Induced turbulence affects the heat transfer downstream of the bend causing the Nusselt number and the friction factor to increase substantially. Overall, the heat transfer increases at the cost of an increased friction factor and the resultant pressure drops after the bend.