Synthesis and thermal properties of 1-octadecanol/nano-TiO2/carbon nanofiber composite phase change materials for thermal energy storage

Abstract

In this work, novel composite phase change materials (CPCM) were synthesized, which consist of 1-octadecanol (OD), nano-TiO2 and carbon nanofiber (CNF). The OD acted as the phase change material, and nano-TiO2 was used as the supporting structure. The CNF was added to promote thermal conductivity. Some tests were performed to identify the characteristics of the CPCM. The results of Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD) indicated that the combination of all the raw materials was physical. The scanning electronic microscope (SEM) was used to determine the microstructure of the CPCM. The results of differential scanning calorimeter (DSC) showed that the melting temperature and latent heat of CPCM3 (the mass fraction of CNF was 4 %) were 57.6 °C and 209.3 J/g, respectively. For liquid-solid phase change process, the solidifying temperature and latent heat were 57.2 °C and 126.7 J/g. For solid-solid phase change process, the solidifying temperature and latent heat were 51.0 °C and 69.1 J/g. Thermogravimetric analysis (TGA) test results indicated that CPCM possesses good thermal stability. Thermal conductivity of the CPCM3 was 0.43 W/m⋅K, which is 1.34 times higher than that of OD/nano-TiO2 composites (NPCM). After 100 thermal cycles, there was no obvious change in the latent heat and microstructure of the CPCM3. Therefore, the CPCM3 is a promising composite phase change material for thermal energy storage.