Simulation on gas-molten salt heat transfer in bubble column for solar thermal storage

The charging and discharging of molten salt thermal storage is of great importance to the operation and maintenance of the solar power plant. The molten salt bubble column is proposed for solar thermal storage, which is regarded as direct contact heat exchanger. The gas from the solar field is directly injected into the molten salt bubble column. High heat transfer rates can be achieved between the gas and the molten salt due to the direct contact. Numeric study on the hydrodynamics and heat transfer characteristic of the gas molten salt bubble column is carried out based on the two fluid model. The effect of the superficial gas velocity, gas inlet temperature and static liquid height are discussed. It is found that the volumetric heat transfer coefficient increases by increasing the superficial gas velocity and decreases by increasing the static liquid height. The distribution of the gas volume fraction varies from uniform flow to non-uniform flow and the heat rate become large as the gas superficial velocity increases. (C) 2019 The Authors. Published by Elsevier Ltd.