Simulation Of The Thermophysical Properties Of Molten Chloride Salts For Thermal Energy Storage

Due to its good thermal characteristics,large heat capacity,good high thermal stability,large operating temperature range,and low cost,molten salts have been used as a high-temperature heat storage material and heat transfer medium for concentrating solar energy.Compared with pure molten salts,mixed molten salts usually have a lower melting point,which can greatly reduce energy loss.Therefore,most of the molten salts used for solar thermal power generation systems is usually a mixture of chlorides.At present,many experiments and simulation studies have been carried out on the chloride molten salts,but no systematic molecular dynamics simulation studies have been carried out on the chloride molten salts elemental,the binary chloride molten salts and the ternary chloride molten salts at the same time.The main research contents include:(1)Perform three commonly used chloride molten salts(KCl,Na Cl and Li Cl),binary mixed chloride molten salts(Li Cl-KCl and Li Cl-Na Cl)and ternary mixed chloride molten salts(KCl-Li Cl-Na Cl)Modeling and structural optimization.(2)Molecular dynamics simulations of the specific heat capacities for the three kinds of chloride molten salts at constant pressure have been carried out.Compared with the experimental values,the absolute relative error of the simulation results of the specific heat capacities for the three kinds of chloride molten salts are all within 6.8%,showing good consistency.Therefore,the specific heat capacity of the binary and ternary chloride molten salt lacking experimental values was predicted offer reference and guiding value.(3)Based on the equilibrium molecular dynamics simulation method,molecular dynamics simulation of the viscosity of the binary and ternary mixed chloride molten salts mixed with three elemental chlorides and different molar ratios have been carried out.As the temperature rises,the viscosity shows a downward trend.Compared with the experimental value,the average absolute relative errors of the three kinds of chloride molten salt is within 15%.The viscosity of the binary and ternary mixed chloride molten salt were predicted.(4)The thermal conductivity is simulated by molecular dynamics based on the reverse non-equilibrium molecular dynamics.The thermal conductivity of the three chloride molten salt elements shows a downward trend with the temperature.Compared with the experimental value of thermal conductivity,except for Li Cl which has an error of 27%,the absolute relative errors of thermal conductivity of the other two chloride molten salts are all within 9%.However,the experimental values of thermal conductivity of binary and ternary mixed chloride molten salts are less,and the absolute relative errors are all within 12.5% compared with the experimental values that can be checked.The comprehensive results showed that the simulation results are in good agreement with the experimental values.The thermal conductivity of the binary and ternary mixed chloride molten salt was predicted.(5)Analyze the molten salt system and local structure through the calculation of the radial distribution function,so as to better understand the thermophysical properties of the chloride molten salt from the microstructure.