A novel CNT encapsulated phase change material with enhanced thermal conductivity and photo-thermal conversion performance

Abstract

Phase change material is one of the most promising materials in thermal energy storage systems. In this work, a new phase change composite of Stearic Acid@Multi-walled carbon nanotubes (SA@MWCNTs) is prepared by a simple vacuum absorption method. The as-prepared composite is determined by scanning electronic microscope (SEM), Fourier transformation infrared spectroscope (FT-IR) and X-ray diffractometer (XRD). The results show that outside diameters of the PCM composite are about 50–60 nm and Stearic Acid is encapsulated in the MWCNTs without chemical reaction. The DSC results indicate that the melting temperature and latent heat of the composite are 59.28 °C and 91.94 J g−1, respectively. The encapsulation ratio of Stearic Acid is calculated to be 47% from the results of the DSC measurements. The as-prepared SA@MWCNTs composite was dispersed into the water to form stable suspension, and the suspension shows remarkable photo-thermal conversion performance with temperature increases from 30 to 80 °C. The receiver efficiency of this new kind of heat transfer fluid maintain 85% in wide temperature range. Furthermore, the PCM composite could maintain its phase transition perfectly after 50 melting–freezing cycles, and no leakage of paraffin was observed by SEM. The high heat storage capability and excellent photo-thermal conversion performance of the composite enable it to be a potential material to store solar energy in practical applications.