Abstract:

In order to develop a low-cost，good thermal performance of the composite phase change heat storage material，NaCl，KCl，CaCl₂ were used as phase change materials，MgO as carrier materials，and nano Bi₂O₃ as thermal conductivity enhancers，chloride/magnesium oxide-based composite phase change thermal storage materials were prepared by mixed sintering method.The chemical compatibility，microstructure，specific heat capacity and thermal conductivity of the chloride/magnesium oxide-based composite phase change heat storage materials by the thermal enhancer were tested and characterized by X-ray diffraction，scanning electron microscopy，synchronous thermal analyzer and DRL thermal conductivity.The results showed that the thermal physical properties of the thermal enhancer nano-bismuth oxide were the best when the content of 2%（mass fraction），the specific heat capacity was 1.16 J/（g·K），the heat storage density was 232.93 J/g，and the thermal conductivity was 1.61 W/（m·K）.Compared with the addition of thermal conductivity enhancer，the specific heat capacity was increased by 40%，the thermal conductivity was increased by 55%，and the heat storage density was increased by 9%.The prepared chloride/magnesium oxide composite phase change heat storage material always maintained a fixed form during use，the specific heat capacity and thermal conductivity were greatly improved，and it had good thermal stability at high temperatures.This study provided a low-cost and high-performance thermal storage material for the field of high-temperature thermal storage，which had broad application prospects in thermal energy storage systems.

Key words: chloride salt, magnesium oxide, thermal conductivity enhancer, bismuth oxide nanoparticles, composite phase change thermal storage material, thermal physical properties