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金属泡沫是一种高导热性多功能材料,内部传热有明显的局部非热平衡特性,而在导热中的热响应特性与外界环境密切相关.本文基于两方程模型研究了填充固体石蜡的金属泡沫复合材料在非稳态过程中的热响应特性.结果表明,金属泡沫与石蜡间存在局部非热平衡效应,需采用两方程模型计算.当环境温度随时间作周期波动时,金属泡沫内温度场也呈周期波动,并且,随环境温度波动周期的增大,局部非热平衡效应先增大后减小,即存在一个共振周期使得局部非热平衡效应最明显.在外界温度波动幅度一定时,金属泡沫内温度振幅随波动周期的增大呈对数趋势增大,不同位置振幅的衰减程度不同,距加热面越远衰减越多.本文还详细讨论了金属泡沫的孔隙率、孔密度、热扩散率,以及石蜡中含纳米颗粒添加物对复合材料热响应特性的影响程度.在实际应用中,应综合考虑这些影响因素,从而使该复合材料的换热性能达到最优.本文揭示了金属泡沫导热中金属骨架相和填充固体相的温度差异,对于多孔介质非稳态热传导的局部非热平衡特性具有直接的科学意义.
Metallic foam is a kind of multi-functional material with high thermal conductivity and has obvious local non-thermal balance characteristic in internal heat transfer, while the thermal response in thermal conductivity is closely related to the external environment.In this paper, based on the two-equation model, The results show that there is a local non-thermal equilibrium effect between the metal foam and the paraffin, which needs to be calculated by the two-equation model. When the ambient temperature fluctuates with time, the temperature field in the metal foam With the increase of ambient temperature fluctuation period, the local non-thermal equilibrium effect first increases and then decreases, that is, there is a resonance period which makes the local non-thermal balance effect most obvious.When the external temperature fluctuation is constant, The amplitude of temperature increases logarithmically with the increase of the fluctuation period, and the attenuation amplitude of different positions is different, the farther away from the heating surface, the more attenuation.The porosity, porosity, thermal diffusivity, As well as the impact of the inclusion of nanoparticles in the paraffin on the thermal response characteristics of the composite.In practical applications, Which can make the heat transfer performance of the composite material reach the optimal.The paper reveals the temperature difference between the metal matrix phase and the filled solid phase in the metal foam thermal conduction and has a direct science for the local non-thermal balance characteristic of the non-steady state heat conduction in porous media significance.