Biochar engineered phase change material: enhancing octadecane for next generation thermal energy storage applications

Phase change materials (PCMs) possess viable solution for thermal energy storage systems in terms of latent heat storage. However, due to insufficient thermal conductivities, these materials cannot be employed effectively for energy storage applications. This work integrated novel combination of octadecane PCM and groundnut shell biochar (GNB) for better thermal transfer efficiency. The bio-waste derived GNB particles were synthesized and combined with octadecane PCM by adopting two-step material preparation technique. As per outcomes of the work, the physiochemical evaluation validated the chemical compatibility of GNB/octadecane composites. Besides, GNB microstructures and its interaction with octadecane PCM for thermal network development were illustrated using Scanning Electron Microscopy (SEM). In addition, latent heat melting enthalpy showed that composite with 0.7 wt% integrated GNB micro/nanoparticles exhibited 244.4 J/g. Further, maximum of 113.5% improvement in thermal conductivity was obtained employing GNB particles. Furthermore, photo-transmittance observation demonstrated 57.8% decrement in transmissibility with increment in photoabsorbance. Moreover, thermal stability of all prepared composites was validated by thermogravimetric evaluation. Therefore, the GNB/octadecane composite significantly enhanced the thermal conductivity, reduced transmissibility, shown chemical and thermal stability along with cyclic stability. The preferred achieved characteristics for prepared composite rendered it a promising composite for efficient thermal energy storage.