多孔结构体材料热整流效应  

Thermal rectification enhancement based on porous structure in bulk materials

作　　者：邵春瑞 李海洋[1] 王军[1] 夏国栋[1] Shao Chun-Rui;Li Hai-Yang;Wang Jun;Xia Guo-Dong(Beijing Key Laboratory of Heat Transfer and Energy Conversion,MOE Key Laboratory of Enhanced Heat Transfer and Energy Conservation,Beijing University of Technology,Beijing 100124,China)

机构地区：[1]北京工业大学,强化传热与过程节能教育部重点实验室暨传热与能源利用北京市重点实验室,北京100124

出　　处：《物理学报》2021年第23期320-329,共10页Acta Physica Sinica

基　　金：国家自然科学基金(批准号:51776007);北京市科技新星计划(批准号:Z191100001119033);北京市教委青年拔尖人才培养计划(批准号:CITTCD201904015)资助的课题.

摘　　要：基于傅里叶导热定律,两种具有不同热导率温度依赖特性的材料组合而成的两段式组合材料可以实现热整流效应.本文提出在体材料上均匀布置多孔结构,通过多孔结构孔隙率调整材料的热导率参数,进而强化热整流效应.基于有限元方法和有效介质理论,计算并分析了温差和孔隙率等参数对体材料热整流系数的影响.计算结果表明,温差较大时,孔隙率对对体材料热整流系数的影响较为明显.在热导率随温度升高而增大的材料中布置多孔结构,一般会降低系统的热整流系数;若在热导率随温度升高而减小的材料中布置多孔结构,则存在一个最佳的孔隙率,相对于无多孔结构的系统,其热整流系数可以提高2-3倍.本文研究结果为体材料热整流系数的调控提供了新的思路.Thermal rectification effect refers to an asymmetric heat transfer phenomenon(namely,the amount of heat flux depends on the direction of temperature gradient).A two-segment bar made of two materials that have thermal conductivities with different temperature-dependence,can realize the thermal rectification effect.In the present paper,we propose to use porous structure on the bulk material to modify the thermal conductivity of bulk material.It is found that the thermal rectification effect can be enhanced by the porous structure.The finite element method and effective medium approximation are used to analyze the influence of porosity on the thermal rectification ratio of the two-segment system.The calculation results are consistent with each other.Under low temperature bias,the effect of the porosity is weak,while its influence becomes very significant when the temperature difference is high.Usually,thermal rectification ratio decreases if the porous structure is made on the segment whose thermal conductivity increases with temperature increasing.If the porous structure is made on the segment with negative temperature-dependent thermal conductivity,an optimal porosity can be found.For low porosity,the forward heat flux keeps almost unchanged while the reverse heat flux decreases by more than half,and the thermal rectification ratio can be increased to twice or more than thrice that in the case of no porous structure.For a fixed temperature difference,the influence of porosity on the thermal rectification ratio increases with the augment of the power exponent value.

关 键 词：热整流 热导率 多孔结构 有效介质理论 

分 类 号：TB383.4[一般工业技术—材料科学与工程]