相变材料热物理性质的分子动力学模拟

为从微观尺度探寻相变材料的热物性变化机理, 本文采用分子动力学的方法, 构建了由正二十二烷组成的无定形结构的相变材料体系, 采用周期性边界条件以及COMPASS力场对相变材料的比热以及导热系数进行了模拟, 并对纯正二十二烷进行了DSC测试. 结果表明, 模拟所得的相变材料热容与文献实验值的偏差是6.5%, 熔点与DSC实验值的偏差是0.98%. 当温度为288–318 K时, 相变材料的导热系数在0.1–0.4 W·m^-1·K^-1 范围内波动, 且随着压力增大略呈下降趋势. 关键词： 扩散系数 比热 导热系数 分子动力学

Molecular dynamics simulation of the thermophysical properties of phase change material

The phase change material (PCM), which is based on straight-chain alkanes, has received more and more attention for thermal management. To explore the mechanism of the thermal property of PCM from the microscopic scale, the molecular model of the PCM which consists of n-dodecane with amorphous structure is established in this study. The molecular dynamics (MD) simulation is performed with periodic boundary conditions and COMPASS force field. The melting temperature of n-dodecane is also determined by differential scanning calorimeter (DSC). The results show that the deviation of the isobaric heat capacity of the n-dodecane based PCM by MD method from the perviously reported value is 6.5%. The deviation of the simulated melting temperature of the PCM from the value from the DSC analysis is 7.6%. The simulated thermal conductivity of the PCM shows a slightly decreasing trend with pressure increasing, in a range of 0.1–0.4 W·m^-1·K^-1.