泡沫金属孔密度对石蜡相变传热强化的影响机理

Effect of pore density of metal foam on phase change heat transfer enhancement mechanism of paraffin wax

为了探究泡沫金属孔密度对相变材料熔化过程中流动传热特性的影响,通过试验设计并搭建了1套半圆柱形的可视化蓄热装置,分析了孔密度对复合相变材料熔化过程中温度分布、固液相界面、换热系数等热特性的影响机理。结果表明:泡沫金属铜能够提高内部石蜡的温度响应速率,缩短熔化时间,并减小相变材料内部温度梯度;纯石蜡和孔密度为0.20,0.59,0.98 mm^(-1)的铜复合相变材料在石蜡熔化后的温度梯度分别为35.26,12.19,20.49,28.39 K;自然对流换热占比也随着泡沫金属铜孔密度的增加而减小;当加热功率为30 W时,孔密度为0.20,0.59,0.98 mm^(-1)的铜复合相变材料自然对流占比分别为20.72%,19.33%,18.24%,且自然对流占比均小于50%,表明在填充率为1.28%的条件下,泡沫金属铜复合相变材料的传热机制以热传导为主。研究结果可为相变蓄热系统的设计提供参考。

To investigate the influence of pore density of metal foam on the flow and heat transfer characteristics of phase change material(PCM)during the melting process,a semi-cylindrical visual heat storage device was designed and constructed by experiment,and the influence mechanisms of pore density on thermal characteristics,including temperature distribution,solid-liquid phase interface,and heat transfer coefficient,were analyzed.The findings reveal that the inclusion of copper metal foam(CMF)can enhance the temperature response rate of paraffin wax,reduce the melting time,and decrease the internal temperature gradient of PCM.Specifically,the temperature gradients of the pure paraffin wax and the copper metal foam with three kinds of pore densities after adding 0.20,0.59,0.98 mm^(-1) after complete melting of PCM are 35.26,12.19,20.49,28.39 K,respectively.Additionally,the proportion of natural convection heat transfer decreases with the increase in the pore density of CMF.For a heating power of 30 W,the natural convection proportions of 0.20,0.59,0.98 mm^(-1) CMF composite PCM are 20.72%,19.33%,18.24%,respectively,and all proportions are less than 50%,indicating that the heat transfer mechanism in the CMF composite PCM at a filling rate of 1.28%is dominated by heat conduction.The research results can provide a reference for the design of phase change energy storage system.