Enhancement of ceramic foam modified hierarchical Al2O3@expanded graphite on thermal properties of 1-octadecanol phase change materials

The porous Al2O3 ceramic foam was composited with expanded graphite (EG) by calcination method to obtain Al2O3@EG composite with hierarchical pores. The specific surface area of Al2O3@EG composite was 2.3 times that of EG, which can better enhance the thermal conductivity and heat transfer performance of phase change materials (PCMs). The stable composite PCMs with high thermal conductivity and energy storage density were prepared via vacuum adsorbing 1-octadecanol (OD) in Al2O3@EG. The thermal conductivity of the modified OD containing 10 wt% Al2O3@EG was 4.5 times that of pure OD, while maintaining a high phase change enthalpy, approximately 200 kJ/kg. The results of SEM and EDS indicated that Al2O3 foam particles dispersed equably on the surface of EG without obvious agglomeration. The XRD and FTIR results revealed that OD, Al2O3 and EG were physically combined. The prepared OD/Al2O3@EG composite PCMs with high thermal conductivity and large energy storage density can be promising for low temperature heat storage, such as industrial heat recovery system, comfort applications in buildings and textiles, solar energy system, etc. This study provides an innovative idea for the application of porous ceramic foams in the field of solar energy storage PCMs modification.