Thermophysical characteristics evaluation of carbon and metal oxide-based hybrid phase change materials for thermal energy storage applications

Phase change materials (PCM) have limited practical applications due to their low heat conductivity. The main goal of this work is to improve the thermophysical properties of PCM by adding different compositions of hybrid carbon and metal oxide-based nanoparticles for incorporation into hybrid photovoltaic/thermal solar systems to accommodate the built environment and thermal energy storage as a building envelope for thermal comfort. Three types of nanoparticles have been selected including Graphene, Al 2 O 3 , and ZnO and synthesized samples with the combinations of 0.5 wt% Al 2 O 3 + 2 wt% ZnO, 0.75 wt% Al 2 O 3 + 2 wt% ZnO, 1 wt% Al 2 O 3 + 2 wt% ZnO, 3 wt% Graphene + 2 wt% ZnO, and 3 wt% Graphene + 1 wt% Al 2 O 3 respectively. All the synthesized hybrid nano-PCM (HNPCM) samples were characterized by utilizing SEM and EDX, FTIR, TGA, thermal conductivity, DSC, and thermal images to study the microstructural features, chemical bonding, thermal stability, latent heat of fusion/solidification, and peak melting/solidification temperature of the samples. The key outcomes reveal that the uniform dispersion of hybrid nanoparticles and the best chemical and thermal stability were obtained in the case of HNPCM-5 (3 wt% Graphene + 1 wt% Al 2 O 3 ). 480%, 430%, 405%, 230%, and 60% enhancement in thermal conductivity, and the optimum values of latent heat of fusion of 145.35, 149.18, 150.37, 147.87, and 145.83 J/g were achieved for the samples of HNPCM-5, HNPCM-2, HNPCM-1, HNPCM-3, and HNPCM-4, respectively in comparison of pure PCM. Finally, the enhancement of specific heat capacity, thermal conductivity, and the reduction of supercooling indicate that the sample HNPCM-5 (3 wt% Graphene + 1 wt% Al 2 O 3 ) can be effectively employed in thermal management applications. As the composite prepared was thermally stable till 250 °C, hence may be utilized for solar thermal and low concentrated photovoltaic applications but not limited to these.