Composite phase change materials with thermal-flexible and efficient photothermal conversion properties for solar thermal management

Composite phase change material (CPCM) with the advantages of high enthalpy and constant temperature phase change, has been widely used in many fields, such as photovoltaic thermal system, building envelope structure and so on. However, conventional CPCM is often rigid, poor light absorption and low thermal conductivity, which limits the application of solar energy utilization. In this paper, a novel Paraffin wax/Thermoplastic elastomer/Carbon nanotube(PA/SEBS/CNT) with shape stability, thermos-flexibility and high photothermal conversion efficiency was prepared, PA as the phase change material, SEBS as the flexible material and CNT as the light-absorbing material. The results show that the addition of CNT increases the absorbance of PA/SEBS from 0.3 to 1.0, and the photothermal conversion efficiency of PA/SEBS/CNT-10 % is as high as 96.17 %. In addition, the CPCM also has a high enthalpy value of 180 J/g, and a high thermal conductivity of >0.3403 W/(m·K), and also exhibits shape-driven memory. At the same time, outdoor photothermal experiments show that PA/SEBS/CNT has excellent photothermal conversion performance under real sunlight, and the highest temperature can reach 99.51 °C. The new CPCM developed has a broad application prospect in solar thermal systems.