Eco-friendly groundnut shell biochar-based nanocomposite organic phase change material for thermal energy storage

Abstract Phase Change Materials (PCMs), aids in decreasing total energy consumption through passive thermal regulation. Nevertheless, low conductivity of the energy storage material poses challenges for effective thermal energy charging and discharging. To boost the thermo-physical characteristics of PCM, a range of nanomaterials with diverse shapes, structures, and sizes are utilized. However, it is evident that many of these nanoparticles are not only expensive but also carry toxicity concerns and are not completely sustainable. Environmentally sustainable and thermally efficient nano-enhanced PCMs with enhanced thermal characteristics are essential for effective thermal energy storage (TES). Meanwhile, investigating new dimensions in the use of biochar particles is an intriguing field of study. This work reports the development of a three-dimensional, mesoporous structured carbon-based groundnut shell biochar (GNB), achieved through a green synthesis technique in tube furnace at 800 ℃ to energize organic PCM. The green synthesis of GNB particles is dispersed with paraffin (organic PCM with energy storage enthalpy of 155-160 J/g and phase transition temperature of 56 ℃) using a two-step method to produce a PCM/GNB nanocomposite. GNB presents a viable option due to its cost-effectiveness, porous structure, which contribute to enhanced binding, consistent dispersion, and improved intermolecular interactions with PCM. The developed nanocomposite samples of PCM/GNB are characterized using sensitive equipment’s to examine the morphological behaviour, to evaluate the chemical stability, optical absorbance and thermal conductance. Results depicts increase in thermal conductivity of paraffin from 0.21 W/(m⋅K) to 0.372 W/(m⋅K) with GNB particle ascribed by the ability of the carbon porous material to develop thermal networks. Likewise, owing to the mesoporous structure supporting multiple reflection of the incident radiation the developed PCM/GNB nanocomposite exhibits higher energy absorbance of 156.5% on comparison to paraffin. With the thermophysical properties established, the developed GNB composite PCM is expected to make a significant contribution to applications focused on thermal regulation.