基于焓法的固-液相变格子Boltzmann模型

The Enthalpy Based Lattice Boltzmann Model for Solid-Liquid Phase Change

潜热储能系统中的相变材料固液相变问题是一个重要的多相流动问题。本文研究了在具有不同类型源项下的焓法格子Boltzmann相变模型在还原温度场分布上的特性。为了消除外力项对温度场的额外影响,本文对源项进行了修正,并通过求解单区域相变问题和自然对流相变问题,验证了由Chapman-Enskog展开得到的焓守恒方程中源项的影响。结果表明,在单区域相变问题中,改进模型的温度分布更加准确。另外,在有相变的自然对流问题中,没有潜热附加项的改进模型的熔化过程比其他模型略慢,同一时刻的最大液相率与最小液相率之差小于0.01。

The solid-liquid phase change is an important multiphase flow problem for phase change material in latent heat energy storage.The enthalpy lattice Boltzmann phase change model with different types of source terms has been studied in this paper.In order to eliminate the additional effect of external force term on the temperature field,the source term is modified.The effect of additional term in the Chapman-Enskog expansion of enthalpy conservation equation is verified by solving the single-region phase change problem and the natural convection phase change problem.The results show that the temperature distribution of the improved model is more accurate in the single-region phase change problem.In addition,in the natural convection problem with phase change,the melting process of the improved model without latent heat error term is slightly slower than that of the other models,and the difference between the maximum and minimum liquid phase rate at the same time is less than 0.01.