Porous structure optimization of biochar composite PCM: an experimental and molecular dynamics simulation study

Biochar is an ideal low-cost and sustainable porous carbon matrix for high-performance composite phase change materials (CPCM). In this study, a porous carbon material with a large proportion of mesopores (72.4 %) and a large specific surface area (1249.8 m²/g) was prepared by the chemical-physical coupled activation method using waste pine wood chips as the carbon source. The law of the effect of activation conditions on the pore structure was obtained. CPCM was prepared from this material, and the thermophysical properties and thermal stability of CPCM were analyzed. The encapsulation properties of biochar on fatty acid phase change materials (PCM) with different carbon chain lengths were analyzed using experimental and molecular dynamics simulation methods. The results showed that biochar has a better adsorption effect when the average pore size of biochar is larger than the carbon chain length of PCM. Meanwhile, the naturally formed semicircular pore structure is more favorable for PCM adsorption. The results provide theoretical guidance for the design of new biochar-PCM.