Exfoliated graphite/paraffin nanocomposites as phase change materials for thermal energy storage application

Nanofluid paraffin based composites were prepared as phase change materials for thermal energy storage applications by dispersing exfoliated graphite (EG) into paraffin with intensive ultrasonic irradiation without any dispersants. Under intensive ultrasonic irradiation, EG was stripped as exfoliated graphite micro/nanoplatelets (EGP). The influence of EGP as heat diffusion promoters on improving thermal properties of paraffin was evaluated. As measured by a laser flash technique, the thermal conductivity of paraffin/EGP composites at room temperature increases with increasing EG mass fraction. After suspended in a water bath for 72 h, EGP still has good dispersion in melting paraffin. All the characteristic Fourier transformation infrared spectral peaks of paraffin and paraffin/EGP composites were observed. These paraffin/EGP composites show a good thermal reliability. Their heating and cooling rates are significantly improved upon the addition of EGP. Hence, the use of EGP is effective to improve thermal conductivity of paraffin with acceptable reduction in its latent heat storage capacity.