Modification Of Thermal Properties Of Nitric Acid Molten Salt And Thermal Storage Performance Under Low Temperature Weather Conditions

Nitric acid molten salt heat storage system is a supporting system for solar power generation projects,which can overcome the shortcomings of discontinuity and instability of solar power generation.The research and application of nitrate in molten salt storage and heat storage in China is just beginning.In view of the blank of the theory and application of the regenerative theory and application of the molten salt of nitric acid under the low temperature climate,this paper adopts the method of building a test platform for the heat transfer of nitric acid with molten salt,which is suitable for low temperature climate conditions,and studies the heat transfer of the molten salt in the nitric acid under the low temperature climate conditions.In this paper,the enhancement of thermal properties of nitric acid molten salt was studied.Through the screening of the reinforced modified materials and the study of the modified process methods,the thermo physical properties of the modified samples were made,and the modified samples were detected and analyzed,and the related factors of the modified material,technology and modification process were discussed.We built and completed the outdoor test platform for nitric acid molten salt heat transfer,which is suitable for low temperature weather conditions.The molten salt thermal storage test was carried out on the platform built on the molten salt transfer heat storage platform.The results show that the regenerative efficiency of the molten salt is 95~96%.The molten salt transfer heat storage experiment of nitric acid has been completed on the platform.At low temperature,molten salt decreases by 8.1?in the tank,and the heat flux of heat dissipation is25.3W/m~2.The molten salt of nitric acid has strong corrosiveness to the common carbon steel.The pipes and equipment that have direct contact with the high temperature molten salt can not use carbon steel.It is appropriate to use austenitic stainless steel and the three kinds of austenitic stainless steel of 304,321 and 316 at high temperature of nitric acid to be 0.0019mm/a,0.0026mm/a and 0.0030mm/a respectively,and the three kinds of stainless steel are high temperature.Nitric acid molten salt is"very resistant to decay"and can be used for direct contact with high temperature molten salt equipment and pipelines.To sum up,this research aims at the blank of the research and application of the heat and storage of the molten salt in the low temperature climate.The first design and construction of the outdoor large-scale outdoor nitric acid molten salt heat storage test platform is designed and built for the low temperature climate conditions,and the initial experiments on the parameters of the heat transfer,heat storage and heat transfer process of the nitric acid molten salt are preliminarily tested.The metal corrosion characteristics of acid molten salts were studied.The completion of this study has laid a solid foundation for the in-depth study and application of the heat and storage system for the molten salt of nitric acid under the low temperature climate,and provides a powerful reference for the extensive application of the heat and storage system of the molten salt of nitric acid to the solar light and heat generation in the cold region.