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为更有效地预测定形相变材料的有效导热系数,以高密度聚乙烯/石蜡定形相变材料为对象,在分形理论的基础上,考虑空腔的分布和石蜡不同相态下的体积变化,建立一种新的导热系数模型——分形-空腔模型。采用准稳态平板法对此模型进行验证,探讨多个参数对有效导热系数的影响。结果表明:该模型的预测值更加符合实际。提高石蜡含量、体积收缩率、初始空腔率、分形维数等参数均会影响定形相变材料的导热系数,初始空腔率对熔融状态下的热导率的影响强于凝固状态下的影响。
In order to predict the effective thermal conductivity of the shaped phase change material more effectively, taking the high density polyethylene / paraffin phase change material as the object, on the basis of the fractal theory, taking into account the distribution of the cavity and the volume change of paraffin in different phases, A New Model of Thermal Conductivity - Fractal - Cavity Model. The quasi-steady-state plate method is used to verify the model to explore the effect of multiple parameters on the effective thermal conductivity. The results show that the predictive value of this model is more realistic. Increasing the paraffin content, volume shrinkage, initial cavity ratio, fractal dimension and other parameters all affect the thermal conductivity of the shaped phase change material. The effect of the initial cavity ratio on the thermal conductivity in the molten state is stronger than that in the solidified state .