Delignified wood/capric acid-palmitic acid mixture stable-form phase change material for thermal storage

Abstract

In this study, wood was delignified, and the capric-palmitic acid eutectic (CA-PA) mixture was impregnated into the delignified wood (DW) to create a stable-form phase change material (DW/CA-PA SFPCM) using a vacuum impregnation method. Subsequently, the properties of the SFPCM were investigated by scanning electron microscopy (SEM), FTIR, differential scanning calorimetry (DSC), thermal gravimetric analysis (TG), and hot-disk thermal constant analysis. It was found that the impregnation ratio of the CA-PA mixture into the DW reached 61.2% without leakage. SEM results showed microscale pores generated in the organized cell wall of the DW compared with wood. The pores of DW were filled completely. By contrast, the pores of wood were partially filled. The CA-PA mixture and the DW was physical combination from FTIR result. The SFPCM had a phase-transition temperature of 23.4 °C and high latent heat of 94.4 J g−1. The DW/CA-PA SFPCM had a high thermal stability due to the fact that the working temperature (i.e. sun radiation temperature) was much lower than the decomposition temperature. It also had great thermal reliability. The thermal conductivity of the SFPCM improved significantly by 133.3%. By the above analysis, the SFPCM had superior properties, which make it to be potential material by storing and releasing solar thermal energy in practical applications.