Abstract:

As high temperature heat transfer fluids, hybrid nitrate salts play a promising role in application of concentrating solar thermal power system. In this study, the heat capacity of NaNO₃-KNO₃-LiNO₃ ternary hybrid nitrate heat storage materials were effectively enhanced by doping SiO₂ nanoparticles with aqueous solution method. With comparison of different mass ratio of nanoparticles, we found that lower mass ratio of nanoparticles has more effective enhancement on heat capacity. The effect of agglomeration of nanoparticles on heat capacity enhancement was also studied. By using polyvinylpyrrolidone (PVP), we reduced the agglomeration of nanoparticles and the dispersity of nanoparticles in nitrate salts was improved which showed furtherly enhancement of heat capacity of nitrate salt heat storage materials. Combined with the results above, we introduced the interface thermal resistance and semi-solid layer model, and the mechanism of heat capacity enhancement of nitrate salt materials by doping nanoparticles was discussed.

Key words: heat capacity, nitrate salt, heat storage, nanoparticles, polyvinylpyrrolidone