Heat Transfer Performances of Molten Salt in Spirally Grooved Solar Receiver Tube

Solar heat receiver is currently one of the important research topics of renewable energy. In present article, experimental measurements and numerical analyses are conducted to investigate the heat transfer performances of high temperature molten salt in spirally grooved solar receiver tube. The molten salt is used as a working medium to study the heat transfer coefficients of spirally grooved solar receiver tube on the heat transfer platform. Experimental results indicated that the spirally grooved tubes can evidently enhance heat transfer, and its heat transfer coefficient increase with the grooved height and Reynolds number. According to the simulation results, the heat transfer coefficient rises with Reynolds number, while the hydraulic resistance coefficient drops quickly. The flow field in the spirally grooved tube periodically develops along the flow, and the circumrotating flow plays an important role in heat transfer. Above the groove, the flow and thermal boundary layers are obviously reduced. As a result, the groove height increment can obviously benefit heat transfer of solar receiver, and that has a good agreement with experimental results.