壳核结构纳米颗粒阵列消光效应和近场辐射传热

Extinction Effect and Near Field Thermal Radiation in Core-Shell Nanoparticle Arrays

通过改变壳核结构纳米颗粒半径比率和材料可改变纳米流体的光谱特性。本文采用Quasi-Static近似的Rayleigh散射方法,分析计算处于非独立散射状态下壳核结构纳米颗粒的消光效应,并采用波动电动力学方法计算了相应体积分数下纳米颗粒间的近场辐射传热。结果表明,壳核结构纳米颗粒消光系数与半径比、体积分数、粒子内外壳材料有关,近场辐射传热量与温度、间距、体积分数有关。比较辐射导热系数、近场辐射等效导热系数、有效导热系数可见,在颗粒均匀分布假设下,体积分数f_x>0.6%且距离波长比小于0.5时,采用波动电动力学的方法颗粒阵列间近场辐射作用可忽略。

Core-shell nanoparticles vary the spectrum characteristics in nanofluids by changing the radius ratio or the material.In this paper,the quasi-static approximation and the Rayleigh scattering method are used to obtain the extinction effect of core-shell nanoparticles in the dependent scattering region.The fluctuating electrodynamics method is used to obtain the near field thermal radiation between the nanoparticles.The results show that the extinction coefficient is related to the radius ratio,volume fraction,and material,while the near field thermal radiation changes with temperature difference,distance,and volume fraction.The comparison for the radiative thermal conductivity,the near field radiative thermal conductivity,and the effective thermal conductivity indicates that,assuming the nanoparticles are uniformly distributed,the near field thermal radiation between the nanoparticle arrays calculated by the fluctuating electrodynamics method can be neglected when the volume fraction fv0.6%and the distance-wavelength ratio is smaller than 0.5.