Preparation and characterization of carbon nanotube microcapsule phase change materials for improving thermal comfort level of buildings

The phase change material (PCM) microcapsule is a common high-performance storage technology of thermal energy. However, the organic wall with low thermal conductivity for PCM reduces the efficiency of heat storage and release. In this study, the novel carbon nanotube-doped phase change materials (C-PCMs) were developed. Scanning electron microscope test (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and the thermogravimetric analysis/infrared spectrometry (TG-IR) were used to analyse the composite structure and thermal performances. The results indicate that C-PCMs are small and regular in spherical shape. When C-PCMs suffer from heat, the shell can maintain integrity below 165 °C. Furthermore, the carbon nanotubes in the shell play as a channel to connect the inside with the outside and improve the efficiency of heat transfer. The DCS test of the samples showed that the latent heat of C-PCMs and PCMs were 112.25 J/g and 116.18 J/g, respectively. The initial phase transition temperature of C-PCMs is 28.97 °C, which is 0.5 °C lower than that of PCMs. The results of the model room test suggested that the composite filled with C-PCMs reduces indoor temperature fluctuations and exhibits the potential for enhancing energy savings and the thermal comfort of buildings.