Enhanced thermal conductivity of palmitic acid/copper foam composites with carbon nanotube as thermal energy storage materials

Palmitic acid (PA)/copper foam composites with carbon nanotubes (CNT) composite phase change materials (CPCM) were prepared by melting impregnation. PA was used as phase change material (PCM), and copper foams with different pore density (40, 80 and 110 PPI, PPI: Pore Per Inch) were used as supporting materials. CNT with different mass fractions (1%, 3% and 5%) were added to further improve the thermal conductivity of the CPCM. Chemical structure and crystal structure of the composites were measured by Fourier transform infrared spectroscopy (FT-IR) and X-ray diffractometer (XRD) respectively, and it was proved that PA was physically adsorbed in copper foams. The microstructures of the CPCM were observed by scanning electron microscope (SEM), and PA was well adsorbed by copper foams. Differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) were used to test thermal properties of the CPCM, and the results showed that CPCM had high latent heat and good thermal stability. Thermal conductivity of the CPCM was measured by thermal conductivity meter (TCM). The higher the pore density of copper foam is, the higher the thermal conductivity of the CPCM is, and the CNT has an obvious improvement effect on the thermal conductivity of the CPCM. Thermal conductivity of the CPCM2 was 3.02 W/(m.K), which was 17.76 times higher than that of the PA. Thermal conductivity of the CPCM6 with mass fraction of 5% CNT was 1.82 times higher than that of the CPCM2.