Effects of MWNTs on phase change enthalpy and thermal conductivity of a solid-liquid organic PCM

The effects of multi-walled carbon nanotubes (MWNTs) on the phase change enthalpy (Delta H) and the thermal conductivity (kappa) of a solid-liquid phase change materials (PCM), palmitic acid (PA), have been investigated. The results showed that both the Delta H and the kappa of the composite were lower than that of PA when the loading of MWNTs was small. As the concentration of MWNTs in the composites increased, the Delta H of the composites was slightly improved and then decreased linearly. However, the kappa of the composites was monotonously increased from the minimum value. When the loading of MWNTs increased to 5% and no surfactant was added, the kappa of the composite was enhanced to be 26% higher than that of PA. The kappa of the composite could be enhanced by CTAB instead of SDBS when the loading of MWNTs was small, as SDBS showed no obvious effect on the kappa of the composites. Furthermore, the effects of surface modification of MWNTs on the Delta H and the kappa of the composites have also been investigated.