Method for enhancing thermal energy storage performance of industrial grade hydrated salts based on phase change

A method for enhancing thermal energy storage performance of industrial grade hydrated salts based on phase change, comprising following steps, where a symbol “m0” represents the mass of the aqueous system of industrial grade hydrated salts after being heated, and the numerical value of m0 is in a range of 10 gram (g)≤m0≤100 kilogram (kg):

• S1:
• heating an aqueous system of industrial grade hydrated salts containing industrial grade hydrated salt of 105-130% of m0 by mass, and taking a sample No. 1 from the system for differential scanning calorimeter (DSC) testing when the mass of the aqueous system of industrial grade hydrated salts is reduced to m0, recording a melting enthalpy of sample No. 1 as ΔH1 and the mass of the remaining industrial grade hydrated salts aqueous solution as m1;
• or, heating and melting a recrystallized industrial grade hydrated salts system of mass m0, taking a sample No. 1 for DSC testing and recording the melting enthalpy of sample No. 1 as ΔH1 and the mass of the remaining industrial grade hydrated salts system as m1;
• and
• S2:
• melting and adding water into, or melting and evaporating the residual aqueous system of industrial grade hydrated salts or the residual industrial grade hydrated salts system with the mass of m1 in step S1 to increase or decrease the mass by 0.4-0.8% m0, then taking a sample No. 2 from the residual system for DSC testing and recording the melting enthalpy of the sample No. 2 as ΔH2, and taking the mass of the residual aqueous system of industrial grade hydrated salts or residual industrial grade hydrated salts system as m2;
• then repeating the melting and adding water or melting and evaporating process until a melting enthalpy ΔHn of a sample No. n that taken from the residual aqueous system of industrial grade hydrated salts or residual industrial grade hydrated salts system with a mass of mn satisfies ΔH2< . . . <ΔHn>ΔHn+1, or the difference between ΔHn and ΔHGR is in a range of −5-5 Joule (J/g), where the residual aqueous system of industrial grade hydrated salts or the residual industrial grade hydrated salts system with the mass of mn is confirmed to be a desired industrial hydrated salts system with improved phase change thermal energy storage performance, with ΔHn being the melting enthalpy of sample No. n+1, and ΔHGR being the melting enthalpy of superior purity hydrated salts, n≥2.