One of the greatest challenges in the application of organic phase change materials (PCMs) is to increase their thermal conductivity while maintaining high phase change enthalpy. To prepare nano-organic composite PCMs for air-conditioning cool storage

nanomaterials with high thermal conductivity

including multi-walled carbon nano-tubes (MWNTs)

Al2O3 and Fe2O3

were respectively added into the organic composite PCMs of caprylic acid/myristyl alcohol (with mass ratio of 73.7 to 26.3)

developed previously in this study. The thermal properties of nano-organic composite PCMs were analyzed by measuring their thermal conductivity coefficient. The kinds and concentrations of nano-materials are key influencing factors. The experiments showed that heat conductivities increased obviously when mass fractions of MWNTs

Al2O3 and Fe2O3 nanomaterials were less than 0.3%

0.4% and 0.8%

respectively. Compared with the original PCMs

heat conductivity increased by 26.3% when mass fraction of MWNTs was 0.3%; heat conductivity increased by 13.1% when mass fraction of Al2O3 was 0.4%; the heat conductivity increased by 32.1% when mass fraction of Fe2O3 was 0.8%. The thermal conductivity enhancement effects were in the order of Fe2O3

MWNTs and Al2O3 at a specific mass fraction (e.g.

0.7%) of nanomaterials. The nano-organic composite PCMs prepared had a limited influence on phase change temperature and phase change enthalpy of the original PCMs

fluctuation of phase change temperature was less than 0.4℃

and the greatest fluctuation range of phase change enthalpy was 1.4%.