基于热力学平衡假设并结合动态边界条件,对大温差下多孔保温材料中的水分迁移及三态相变过程进行数值模拟,并以海绵干燥过程为例给出了实验验证.在数学模型中考虑了由于温差引起的自然对流效应,分析了不同时刻海绵内部的温度、水蒸气浓度、液态水及冰体积分数的分布规律,讨论了材料主要物性参数对水分传递过程的影响.结果表明:数学模型能够实现对大温差下多孔介质中水分传递过程的准确预测;由物性参数分析的结果可知,相比于影响多孔保温材料水分传递的有效扩散系数和孔隙率两个关键物性参数而言,有效导热系数影响相对微弱.%Based on the assumption of thermodynamic equilibrium and combined with dynamic boundary conditions,a mathematical model is developed to simulate moisture migration and three state phase transition process in porous insulation material under large temperature difference,and it is verified by the sponge drying experiment.In the modeling,the effect of natural convection caused by temperature difference is considered.The analysis is conducted on the distribution characteristics of temperature,water vapor concentration,the volume fraction of liquid water and ice in the sponge with evolution of time.The influence of physical parameters on the moisture transfer process is discussed.Finally,it is concluded that the model could accurately predict the process of moisture transfer in porous media under large temperature difference,and from the analysis of physical parameters,the porosity and effective diffusion coefficient are the key factors to affect the moisture transfer in porous insulation material,and the effective thermal conductivity has a lesser impact.
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