均匀及梯度泡沫金属复合PCM熔化特性模拟研究

Simulation Study on Melting Characteristics of Uniform and Gradient Metal Foam Composite PCMs

基于六面通圆孔的均匀泡沫金属结构,构建了泡沫金属复合相变材料(PCM)三维模型,采用高性能计算显卡(GPU)加速的多松弛时间格子玻尔兹曼方法模拟了均匀及梯度泡沫金属复合PCM的瞬态熔化过程。结果表明:随着均匀泡沫金属孔隙率的降低,复合PCM的传热速率提高,潜热储能的能力减弱;对于固定平均孔隙率的不均匀泡沫金属,孔隙率沿导热方向上递增的模型具有最佳的强化传热效果,其完全熔化时间比填充均匀骨架模型和孔隙率在导热方向上递减的骨架模型分别缩短了4.2%和25%,当孔隙率梯度变化方向与导热方向一致时,在高温壁面附近填充低孔隙率泡沫金属能显著强化传热;当两者方向垂直时,熔化速率取决于平均孔隙率,与梯度分布几乎无关。

Based on the uniform metal foam structure with six-sided circular holes,a three-dimensional model of metal foam composite phase change materials(PCMs)was constructed.The transient melting process of uniform and gradient metal foam composite PCMs was simulated by using a GPU-accelerated multi-relaxation time lattice Boltzmann method.The results show that with the decrease of the porosity of the uniform metal foam,the heat transfer rate of composite PCMs is increased and the latent heat storage capacity is weakened;for the non-uniform metal foam with a fixed average porosity,the model with increasing porosity along the heat conduction direction has the best heat transfer enhancement effect,and its complete melting time is 4.2%shorter than that of the framework model with uniform porosity and 25%shorter than that of the framework model with decreasing porosity along the heat conduction direction.When the variation direction of porosity gradient is consistent with the direction of heat conduction,adding low-porosity metal foam near the high temperature wall can significantly improve heat transfer enhancement;while the both directions are perpendicular,the melting rate depends on the average porosity and is almost independent of the gradient distribution.