A novel composite phase change material with paraffin wax in tailings porous ceramics

A new composite phase change material (CPCM) is developed for thermal energy storage applications. The CPCM is fabricated by spontaneous melt infiltration of paraffin wax into a porous ceramic carrier made from industrial waste-iron tailing with a foam-gel casting method. The mechanical and thermal properties of the CPCM can be controlled by adjusting the fabrication parameters (particularly sintering temperature). The porous tailing ceramic shows high porosity (70%−90%) and mechanical strength (0.4–6 Mpa compressive), with good wettability for paraffin wax. The phase composition, microstructure and chemical stability of the CPMC are characterized by analyses with X-ray diffraction (XRD), scanning electron microscope (SEM) and differential scanning calorimetry (DSC). The results demonstrate that paraffin wax well fills the pores without reacting with the tailing material, and the porous medium can efficiently prevent liquid paraffin from leaking. The CPCMs achieve the thermal conductivity of 0.30 ∼ 0.51 W/m K (higher than the base paraffin wax), the bulk density of 1.179 ∼ 0.945 g/cm3 and thermal energy storage density of 71 ∼ 123 kJ/kg. The measured thermal conductivity is in good agreement with results predicted from a universal model. All these results indicate that the new composite phase change material is promising for thermal energy storage applications.