In this study, a kind of phase change materials (PCMs) with a low melting point (around 0 ℃) was prepared using n-decyl alcohol (DA) and lauryl alcohol (LA) as PCM, expanded graphite (EG) as supporting matrix. Nano silicon carbide (SiC) as a thermal conductivity promoter was added to modify the composite PCM. Expanded graphite with strong adsorption performance was used to not only prevent the leakage, but enhance the thermal conductivity. Leakage experiments showed that the maximum adsorption rate of DA-LA in composite PCM was 92 wt.%. The physical properties and chemical compatibility of composite PCM were studied, and the results showed that the raw materials were well absorbed and dispersed homogeneously into the porous structure of the EG, and they were only a physical bond with each other without chemical reaction. The melting and solidification temperature of composite PCM with the SiC mass ratio 3 wt.% was -0.85 ℃ and 1.08 ℃, and the latent heat of melting and solidification was 85.62 J/g and 74.94 J/g, respectively. the thermal conductivity of composite PCM with 9 wt.% SiC addition was 1.61, which was more than 4.19 times that of pure DA-LA. Thermogravimetric Analysis (TGA) experiment showed that composite PCM had outstanding thermal stability and durability. The present study confirms that this composite PCM is a potential candidate for cold energy storage in refrigerator applications.

In this research, myristic-palmitic acid(MA-PA)/ nano silicon dioxide(nano-SiO2) was modified by adding nano silicon carbide(nano-SiC) with high thermal conductivity. The MA-PA/nano-SiO2 composite phase change material (PCM) was prepared by impregnating the MA-PA eutectic mixture as PCM into nano-SiO2 as supporting material. Nano- SiC was added to improve the thermal conductivity of MA-PA/nano-SiO2 composite PCM. Leakage experiments demonstrated that the optimal percentage of MA-PA eutectic mixture adsorbed in nano-SiO2 was 62wt%. The results of thermal conductivity meter measurement showed that the heat transfer coefficient of the MA-PA/nano-SiO2 /nano- SiC composite PCM with 9wt% nano-SiC was 0.776 W/(mK), which increased by 83.02% compared with MA-PA/nano-SiO2 composite PCM. The composite PCM melted at 42.96°C with a latent heat of 88.37J/g and solidified at 44.12°C with a latent heat of 82.45J/g, which were examined by using the differential scanning calorimeter. Thermogravimetric analyzer test results find that composite PCMs had good thermal stability in the working temperature range. Based on the above results, it was known that modified MA-PA/nano-SiO2 /nano- SiC composite PCMs had better thermodynamic properties and were widely applied future in air conditioning condensation heat recovery systems.