System Design And Experimental Research On Molten Salt Heat Transfer And Thermal Storage For Concentrating Solar Utilization

With the background of serious environmental pollution and energy crisis, it will have bright future to develop the renewable and green energy resource such as solar energy. Heat transfer and thermal storage is considered to be the key technology in the high temperature utilization of solar energy.By the support of the National"973"project, plenty of literature was read and the latest development of heat transfer and thermal storage technology of solar energy in the world was grasped. Three different heat transfer and thermal storage schemes used in the gasification of biomass in supercritical water for hydrogen production were designed, and the system with separated storage tank and reactor was chosen as the best scheme by detailed comparison.Acting as the heat transfer and heat storage materials, the characteristics of the working fluid influenced the whole system's efficiency and intending application deeply. Thus, the high temperature heat transfer and thermal storage materials in industry were analyzed and it came to a conclusion that none of them was suitable for the system. So, a new kind of composite molten salt based on sodium chloride, potassium chloride and anhydrous magnesium chloride was studied. Composite molten salts of different purities and proportions were confected, and the melting point and latent heat was measured using the differential scanning calorimeter (DSC). The thermal stability of the composite molten salt was also experimental investigated by melting and freezing for several cycles. It showed that this kind of molten salt had appropriate melting point and favorable thermal stability, and was suit for high temperature heat transfer material. Meanwhile, the physical characteristics of the molten salt such as density, heat capacity, heat conductivity and viscosity were also theoretically calculated.The principle of key equipments in the high temperature heat transfer and thermal storage system such as the high temperature solar receiver, the high temperature molten salt tank, the low temperature molten salt tank, the molten salt to water heat exchangers and the high temperature molten-salt pump was detailed discussed. And the design and type selection of them were also done in the paper.Scheme of experimental test of the performance of the molten salt was designed and the main equipments of the system were manufactured. But due to the time restriction, there is no experimental result was gained in the paper.