Performance and kinetic analysis of paraffin-based fly ash composite phase change materials
摘要
In this paper, paraffin was adopted as the matrix, and fly ash was the supporting material. The composite phase change materials loaded with fly ash in different proportions were prepared utilizing the direct impregnation method. The chemical composition of the composite phase change materials of paraffin–fly ash was characterized by XRD and FTIR. The thermal properties were determined by leakage rate testing and thermogravimetric analysis. The kinetic models and parameters of thermal decomposition of the composite phase change materials were obtained through the Coats–Redfern method and the Melak method. The characterization results demonstrated that the thermal stability of composite phase change materials initially improved and subsequently decreased with fly ash addition. The composite containing 5% fly ash exhibited optimal thermal stability enhancement, while maintaining favorable physical compatibility and chemical stability. Kinetic analysis revealed that the activation energy and pre-exponential factor for paraffin decomposition were determined as 121.92–245.11 kJ mol−1 and 2127.78–12,802.39. The activation energy and pre-exponential factor for paraffin–fly ash composite phase change material exhibited ranges of 146.19–170.54 kJ mol−1 and 1547.36–2253.11. The decomposition reaction of the composite phase-change material with the optimal performance (95% paraffin+5% fly ash) can be described by the R1 model under a heating rate of 5 °C min−1. At heating rates of 10 °C min−1 and 15 °C min−1, the decomposition process of this material is more appropriately described by the R3 model. The corresponding reaction kinetic models have been established.