Effect of pore structure on the thermal stability of shape-stabilized phase change materials

Abstract

To attain the increasing demand for energy in addition with an aim of resolving environmental concerns, a transition from traditional energy systems to renewable resources is crucial. However, renewable energy needs the proper mechanism of harvesting on availability and suitable storage capabilities until it's utilizable necessity. Therefore, effective and consistent energy storage frameworks are crucial for the utilization of stowed renewable energy at a maximum capacity. Pondering that, this study has been focused on the utilization of biochars for efficacious thermal energy storage applications. The shape stabilization efficiency of commercial softwood biochar (EB) has been compared with synthesized bamboo biochar (BA). Both biochars have demonstrated porous and channel-like morphologies and the BET surface areas are measured to be 41.1676 and 9.7213 m2/g, respectively. Paraffin as a phase change material (PCM) is melted and permeated into the biochars to synthesize the biochar composite PCMs. Paraffin to biochar in a 3:1 ratio has been realized as the optimum for both composite PCMs. Maximum heat charging and discharging enthalpies are found to be 96.71 and 94.97 J/g for 1:3 EB-PCM as well as 77.78 and 75.06 J/g for 1:3 BA-PCM composites, respectively. The highest encapsulation ratios are calculated to be 53.49 and 43.02% for 1:3 EB-PCM and 1:3 BA-PCM composites, respectively. Although the enthalpies and encapsulation ratios are found higher in EB-PCM composites, BA-PCM composites have demonstrated superior thermal stability owing to the smaller pore sizes and that has resulted in higher surface tension, capillary action, and effective surface functionalities.

Keywords

• Biochar
• Enthalpy
• Thermal energy storage
• Phase change material
• Composite