Micro-nano particle doping is an important method for the modification of molten salt thermal storage materials.By taking a binary carbonate molten salt mixture of 40Li_2CO_3-60Na_2CO_3 (mass fraction) as the base molten salt

Cu O and Cu Cl_2 as the dopants

three composite molten salt phase change thermal storage materials

namely Cu O-Li_2CO_3-Na_2CO_3

Cu Cl_2-Li_2CO_3-Na_2CO_3

and Cu O-Cu Cl_2-Li_2CO_3-Na_2CO_3

were re prepared separately using a high-temperature melting method.Moreover

the thermal properties of these compounds were tested

and the effects of additives on the modification of binary carbonate molten salts and composite molten salt phase change thermal storage materials were investigated.The results show that

the melting point of the Li_2CO_3-Na_2CO_3 molten salt with 0.24%Cu O addition decreased by 5.2℃

the latent heat of phase change decreased by 98.1 J/g

the average specific heat capacity of the solid phase decreased by 0.39 J/(g·℃)

and the average specific heat capacity of the liquid phase decreased by 0.77 J/(g·℃).The upper limit of the operating temperature increased by 4℃.For the Li_2CO_3-Na_2CO_3-Cu Cl_2 molten salt with 0.06%CuO addition

the melting point increased by 9.6℃

the latent heat of phase change decreased by 15 J/g

the average specific heat capacity of the solid phase increased by 0.07 J/(g·℃)

and the average specific heat capacity of the liquid phase increased by 0.12 J/(g·℃).The upper limit of the operating temperature increased by 17℃.Both molten salts exhibited improved thermal conductivity performance after the addition of Cu O.