Heat transport in aqueous suspensions of alumina nanoparticles
Heat transport in aqueous suspensions of alumina nanoparticles
复制标题
氧化铝纳米颗粒水悬浮液中的热传输
DOI：
10.2514/6.2016-0509
复制
发表时间：
2016
影响因子：
2.7
通讯作者：
V. Yang
中科院分区：
文献类型：
--
作者：
M. Muraleedharan;D. Sundaram;V. Yang
采用平衡态分子动力学模拟方法研究了氧化铝纳米颗粒水悬浮液中的热传输。悬浮液的热导率，计算的格林-久保关系，研究了广泛的体积分数，粒径和温度。颗粒体积分数在1-9%的范围内变化，所关注的颗粒尺寸范围为1-9 nm。温度在300和370 K之间变化。径向分布函数和径向密度分布被用来估计吸附在颗粒表面上的有序基流体纳米层的厚度。重点放在阐明之间的关系的热导率增强和纳米层厚度。结果表明，有效导热系数随颗粒体积分数的增加呈近似线性增加，但随着颗粒尺寸的增加，有效导热系数的斜率减小。纳米层厚度与颗粒体积分数无关。颗粒尺寸对热导率的影响进行了研究的体积分数为5%，温度为300 K，压力为1个大气压。纳米层的厚度几乎保持不变的颗粒尺寸的增加。然而，有效热导率和用粒径归一化的纳米层厚度都随着粒径的增加而急剧下降，并且在粒径约150 nm处达到渐近值。温度对有效导热系数的影响进行了研究，为3 nm的颗粒尺寸和体积分数为5%。热导率随着温度的升高而稳定地降低，而纳米层厚度几乎保持恒定。对于小于10 nm的颗粒尺寸，热导率的增强显著大于现有理论模型的预测。从结果中可以推断出纳米层性质与完全分散的纳米颗粒悬浮液的增强的热导率之间的强相关性。
Equilibrium molecular dynamics simulations are conducted to investigate heat transport in aqueous suspensions of alumina nanoparticles. The thermal conductivity of the suspension, calculated by the Green-Kubo relations, is studied for a wide range of volume fractions, particle sizes, and temperatures. The particle volume fraction is varied in the range of 1-9% and the particle size range of concern is 1-9 nm. The temperature varies between 300 and 370 K. The radial distribution function and the radial density profiles are utilized to estimate the thickness of the ordered base-fluid nanolayer adsorbed on the particle surface. Emphasis is placed on elucidating the relationship between the thermal conductivity enhancement and the nanolayer thickness. Results show that the effective thermal conductivity increases near-linearly as a function of volume fraction, whereas the slope of this function decreases with an increase in particle size. The nanolayer thickness is independent of the particle volume fraction. The effect of particle size on thermal conductivity is studied for a volume fraction of 5%, temperature of 300 K, and pressure of 1 atm. The nanolayer thickness remains almost constant with an increase in particle size. However, both effective thermal conductivity, and nanolayer thickness normalized with particle diameter decreases sharply with increasing particle size and attains an asymptotic value at particle diameter ~ 150 nm. The effect of temperature on the effective thermal conductivity is studied for a particle size of 3 nm and volume fraction of 5%. The thermal conductivity decreases steadily with increasing temperature, whereas the nanolayer thickness remains nearly constant. For particle sizes less than 10 nm, the enhancement in thermal conductivity is significantly greater than the predictions of existing theoretical models. A strong correlation between nanolayer properties and enhanced thermal conductivity of fully dispersed nanoparticle suspensions can be deduced from the results.