Balsa-based porous carbon composite phase change material with photo-thermal conversion performance for thermal energy storage

Photo-thermal conversion is one of the effective ways to utilize solar energy. Regarding the intermittence and instantaneousness of solar energy, using phase change materials (PCMs) can solve this issue by storing the obtained thermal energy. In this paper, Balsa wood (BW) is treated by delignification and carbonization firstly. Then the carbonized wood (CW) with regular pore structure is introduced into the PCMs as the supporting and photo-thermal conversion media by vacuum impregnation method. The microstructure and thermal properties of the woods and composite PCMs are tested by SEM, POM, MIP, FT-IR, DSC, and TG. The results indicate that the CWs present a similar porous structure to BW, and its porosity is as high as 92.03%. The PCMs are packaged in the porous structure of CWs due to the surface tension and capillary forces, and the maximum effective impregnation ratio of the PCMs into the CW-3 reaches to 85.25 wt%. The phase change temperature and latent heat of CW-3/OP44E are measured as 41 °C and 206.3 J/g, respectively. Moreover, the composite PCMs possess a suitable photo-thermal conversion property, and the photo-thermal conversion efficiency of the composite PCM CW-3/OP44E is 90%. The good thermal stability also indicates its potential application in the thermal energy storage system.