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凝聚态物质状态方程的一个数值模型 总被引:1,自引:1,他引:0
建立了凝聚态物质的一个三项式状态方程:以Faussurier平均原子模型为基础计算电子热压和电子热能;以Cowan模型为基础计算离子热压和离子热能;用基于实验数据的半经验拟合公式计算物质的冷压和冷能。用实验数据检验了用平均原子模型计算的平均电离度。将状态方程与Hugoniot关系式相结合,计算了Be和Al的冲击绝热曲线,结果充分地展现出电子在高温、高密度条件下的壳层结构效应。 相似文献
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通常我们在实验结束后,常要查表将其测得值与表中值加以比较,并以此为根据来判断实验结果的正确与否或进行误差分析。但表中的值也是实验测得的,既然是实验测得也就有其测量时特定的各种条件与因素。在实验结果与之比较时,要根据自己实验的具体情况和条件,加以具体分析,不能盲目拿来比较。例如在测定物质的导热系数时,由于导热率受温度影响很大,相同物质温度不同,则导热率不同。纯金属和大多数液体(水例外)的导热率随温度的升高而降低,而非金属和气体的导热率随温度升高而增大,计算时应取用物质平均温度下的数值。 相似文献
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本文用分子动力学模拟方法研究了近固体壁面拟有序液体边界层及其导热特性。得出分子密度沿垂直壁面方向呈衰减分布,且拟有序层内的分子运动方式接近于晶体分子。结合径向分布函数定量分析得出拟有序层的有序程度随固液耦合作用加强而增加。用G-K公式计算了拟有序层的导热系数,发现其与物件尺度、边界条件有密切关系。但在相同的边界条件下,导热系数随有序程度的增加而增加。 相似文献
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制冷剂二元混合物液体粘度预测方程 总被引:1,自引:0,他引:1
针对目前较缺乏适用性强的预测液体混合物输运物性的方法的现状,本文作者通过对大量实验数据的分析和规律研究,提出了一种新的预测直链烷烃和直链烷烃的卤代物类物质液体二元混合物粘度的方程。该方程形式简单,精度可以满足工程应用需要,且具有较广的适用性。 相似文献
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1引言胞腔模型或称自由体积模型早在本世纪30年代就已经提出[’-‘],但由于该模型的重要参数,即自由体积一直无法予以确定,以至于就无法用该模型来计算物质的一系列性质、作者曾于1985年利用胞腔型状态方程导出两个物质特性参数一内压因子和构形因子问,本文根据上述状态方程和两个特性参数导出了计算物质的自由体积公式。从此即可应用自由体积参数计算物质的热力学性质。本文是介绍应用自由体积参数计算纯物质的汽化热的方法。2自由体积模型的液体理论和自由体积的计算自由体积理论最早由Lennard-Jones和Devon-shire用来将液体的… 相似文献
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The paper reports new measurements of the thermal conductivity of mixtures of neon and argon with methane at a temperature of 27.5°C. The measurements have been performed with a transient hot-wire instrument within the pressure range 1 to 22 MPa and the results have an estimated uncertainty of ±0.3%.The thermal conductivity data for the mixtures in the limit of zero density can be represented with the aid of the best available kinetic theory formulae, but not within their experimental uncertainty. The density dependence of the thermal conductivity of the mixtures is adequately described by a semi-empirical correlation scheme based on the modified Enskog theory. 相似文献
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J.J. Van Loef 《Physica A》1977,87(2):258-272
Analytical expressions for the transport coefficients of liquids based on the corrected Enskog theory have been used in order to determine the self-diffusion coefficient (D) for molecular liquids as a function of density and temperature. The liquids considered are those composed of linear molecules and NH3. The calculated D values agree with the experimental ones for those molecular liquids for which experimental self-diffusion data are available. The translational part of the thermal conductivity (λtrans) has also been calculated and compared with the experimental thermal conductivity (λ). It turns out that λtrans for diatomic molecular liquids practically represents the whole of λ in a substantial fraction of the liquid range, indicating that the internal degrees of freedom hardly contribute to the thermal conductivity in these dense liquids. A comparison is made with recently published results based on the modified Enskog theory. 相似文献
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The short-time behavior of the coherent intermediate scattering function for a fluid of hard-sphere particles is calculated exactly through ordert
4, and the other hydrodynamic correlation functions are calculated exactly through ordert
2. It is shown that for all of the correlation functions considered the Enskog theory gives a fair approximation. Also, the initial time behavior of various Green-Kubo integrands is studied. For the shear-viscosity integrand it is found that at densityn3=0.837 the prediction of the Enskog theory is 32% too low. The initial value of the bulk viscosity integrand is nonzero, in contrast to the Enskog result. The initial value of the thermal conductivity integrand at high densities is predicted well by Enskog theory. 相似文献
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The Chapman–Enskog solutions of the Boltzmann equations provide a basis for the computation of important transport coefficients for both simple gases and gas mixtures. These coefficients include the viscosities, the thermal conductivities, and diffusion coefficients. The Chapman–Enskog solutions are also useful for computation of the associated slip and jump coefficients near surfaces. Generally, these solutions are expressed in terms of Sonine polynomial expansions. While it has been found that relatively, low-order expansions (of order 4) can provide reasonable precision in the computation of the transport coefficients (to about 1 part in 1000), the adequacy of the low-order expansions for computation of the slip and jump coefficients still needs to be explored. Also of importance is the fact that such low-order expansions do not provide good convergence (in velocity space) for the actual Chapman–Enskog solutions even though the transport coefficients derived from these solutions appear to be reasonable. Thus, it is of some interest to explore Sonine polynomial expansions to higher orders. It is our purpose in this paper to report the results of our investigation of high-order, standard, Sonine polynomial expansions for the viscosity and the thermal conductivity related Chapman–Enskog solutions for a simple, rigid-sphere gas where we have carried out our calculations using expansions to order 150 and where our reported values for the transport coefficients have been demonstrated to converge to at least 25 significant digits. We note that, for a rigid-sphere gas, all of the relevant integrals needed for these solutions are evaluated analytically as pure fractions and, thus, results to any desired precision may be obtained. This work also indicates how results may be obtained in a similar fashion for realistic intermolecular potential models, and how gas-mixture problems may also be addressed with some additional effort. 相似文献
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Thorne's extension of the Enskog theory to thermal conductivity and viscosity of binary hard sphere fluid mixtures is examined. It is shown that for molecules of the same size and different mass the expression for the thermal conductivity of such a mixture obtained by Longuet-Higgins, Pople and Valleau is identical to the collisional term in Thorne's equation arising from the locally maxwellian velocity distribution. Thorne's equations are evaluated by using the Percus-Yevick approximation for the contact radial distribution functions obtained by Lebowitz. The variations of the transport coefficients are examined as functions of pressure, composition and ratios of diameters and masses of the two species. Some comparison is made with experimental results. 相似文献
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R. Nikolić K. Kelić O. Nešković 《Applied Physics A: Materials Science & Processing》1984,34(3):199-203
The thermal conductivities of seven candidate materials for solar-energy storage were measured as a function of temperature in the solid and liquid states. A drop in thermal conductivity was observed near the melting point. It was shown that the ratio of thermal conductivities in the liquid and solid phases depended on the structure of the material investigated. The vibrational conductivity contribution was calculated and compared with the experimental values for the thermal conductivities. 相似文献
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Different effects of grain boundary scattering on chargeand heat transport in polycrystalline platinum and goldnanofilms 下载免费PDF全文
The in-plane electrical and thermal conductivities of several
polycrystalline platinum and gold nanofilms with different
thicknesses are measured in a temperature range between the boiling
point of liquid nitrogen (77K) and room temperature by using the
direct current heating method. The result shows that both the
electrical and thermal conductivities of the nanofilms reduce
greatly compared with their corresponding bulk values. However, the
electrical conductivity drop is considerably greater than the
thermal conductivity drop, which indicates that the influence of the
internal grain boundary on heat transport is different from that of
charge transport, hence leading to the violation of the
Wiedemann--Franz law. We build an electron relaxation model based on
Matthiessen's rule to analyse the thermal conductivity and
employ the Mayadas & Shatzkes theory to analyse the electrical
conductivity. Moreover, a modified Wiedemann--Franz law is provided
in this paper, the obtained results from which are in good agreement
with the experimental data. 相似文献
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A stochastic model of the revised Enskog equation is considered. A choice of the smearing function suggested by the work of Leegwater is used to apply the model to the repulsive part of the Lennard-Jones potential and the inverse-power soft-sphere potential. The virial coefficients obtained from the equilibrium properties of the models are in excellent agreement with the known exact coefficients for these models. The transport coefficients for the repulsive Lennard-Jones (RLP) model are also computed and appear to be of comparable accuracy to the Enskog-theory coefficients applied directly to a hard-sphere system, although exact results for the RLP with which to make an extensive comparison are not yet available. The pressure and the transport coefficients obtained from the model (shear viscosity, thermal conductivity, and self-diffusion) are compared with the pressure and the corresponding transport coefficients predicted by the Enskog and square-well kinetic theories. 相似文献
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《Physics letters. A》1998,242(3):130-138
We propose a phenomenological approach to quantum liquids of particles obeying generalized statistics of a fermionic type, in the spirit of the Landau Fermi liquid theory. The approach is developed for fractional exclusion statistics. We discuss both equilibrium (specific heat, compressibility, and Pauli spin susceptibility) and nonequilibrium (current and thermal conductivities, thermopower) properties. Low-temperature quantities have the same temperature dependences as for the Fermi liquid, with the coefficients depending on the statistics parameter. The novel quantum liquids provide an explicit realization of systems with a non-Fermi liquid Lorentz ratio in two and more dimensions. Consistency of the theory is verified by deriving the compressibility and f-sum rules. 相似文献