共查询到20条相似文献,搜索用时 15 毫秒
1.
Analysis of equation of state and thermodynamic functions for trans-decahydronaphthalene up to 200~MPa and 446~K
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
This paper develops a modified Tait equation of state(EOS) for trans-decahydronaphthalene with four parameters A,B,V0 and P0 being treated as linear functions of temperature.The coefficients contained in these functions are determined through fitting the experimental compression data in the literature between 293 K and 446 K and at pressures from 10 to 200 MPa.Expressions for the thermal expansivity,isothermal compressibility and thermodynamic quantities are deduced and the numerical results are analytically derived.The numerical results show that the precision of the modified Tait EOS developed in this paper is superior to the EOS in the literature. 相似文献
2.
In the present paper, we have analysed the pressure dependences of thermal expansivity (α
p
) and isothermal compressibility (K
T
) for the liquid hexane and chloroform. We have used the formulae based on the pseudospinodal model and the Sanchez et al [1,2] equation of state obtained from the Pade approximation. The thermal expansion coefficient and isothermal compressibility
follow a power law function of pressures. It is found that the quantities, α
p
as well as K
T
decreases with the increasing pressure. The isothermal compressibility decreases more rapidly in comparison to thermal expansivity.
The pressure at which the spinodal condition is satisfied, i.e.
α
p
and K
T
both tend to infinity, has been found to be a characteristic property of the liquid hexane and chloroform. 相似文献
3.
The thermal expansivity and mean-square thermal vibrational amplitudes were determined as a function of temperature for thorium from first principles total energy calculations using the full potential linearized augmented plane wave (FP-LAPW) method. The coefficient of thermal expansion determined from variation of theoretical potential energy with interatomic separation is ~1.427 × 10?5 K?1 as compared to an experimental value of 1.23 × 10?5 K?1. The mean-square thermal vibrational amplitudes determined as a function of temperature from the theoretically calculated volume-dependent Debye temperature agree well with experimental data derived form neutron diffraction measurements. The melting temperature of thorium, determined theoretically from the mean-square thermal vibrations and the Lindemann rule for melting, is 2234 K, as compared to the reported experimental value of 2021 K. 相似文献
4.
Abstract Results on the temperature- and pressure dependence of the specific volume, thermal expansivity and compressibility of elastomeric compounds are reported. 相似文献
5.
In the present investigation we have explained the thermal and compression properties of HCP iron (Fe) at high pressure with
variable temperature (isobars) and at high temperature with variable pressure (isotherm). The usual Tait equation of state
is modified by incorporating the effect of thermal pressure. The calculated values of pressure for different isotherms and
isochors and thermal expansivity (α) as a function of both temperature and pressure have been compared with those values obtained by Isaak et al and Wasserman et al.
相似文献
6.
Abstract The expansivity of n-hexane was measured through the heat of compression up to 500 MPa in the 243–473 K temperature range. Details about the experiment are given. From the fit to our data, the pressure variation of the specific heat Cp, in the same pressure-temperature domain, is computed; good agreement is obtained with available high pressure data. 相似文献
7.
Constant temperature and pressure molecular dynamics
(MD) simulations are performed to investigate the thermal
expansivity of MgO at high pressure, by using effective
pair-wise potentials which consist of Coulomb, dispersion, and
repulsion interactions that include polarization effects through the
shell model (SM). In order to take into account non-central forces
in crystals, the breathing shell model (BSM) is also introduced into
the MD simulation. We present a comparison between the volume
thermal expansion coefficient α dependences of pressure P
at 300 and 2000~K that are obtained from the SM and BSM potentials
and those derived from other experimental and theoretical methods in
the case of MgO. Compared with the results obtained by using the SM
potentials, the MD results obtained by using BSM potentials are more
compressible. In an extended pressure and temperature range, the α
value is also predicted. The properties of MgO in a
pressure range of 0--200~GPa at temperatures up to 3500~K are summarized. 相似文献
8.
The correlations between the surface tension, shear viscosity, and isothermal compressibility, are investigated for liquid C60 at extended regions of temperature and pressure. An improved equation of state [EOS] is employed, based on hard-core plus three Yukawa potential [HC3YK] which facilitates the analytically accurate series mean spherical approximation [SMSA] formalism for the free energy. The present equation of state is utilized to obtain analytical expressions for the thermodynamic functions of interest and discuss the validity of their mutual relations along the spinodal curve of C60. 相似文献
9.
We present a new method for understanding the changes with temperature of the volume and compressibility of solids. These changes depend on five parameters: V 0, B 0, Θ, γ G and δ T. V 0 and B 0 are the atomic volume and bulk modulus at T?=?0?K, Θ is the Debye temperature, γ G is the Grüneisen parameter, and δ T is the Anderson–Grüneisen parameter. Equations for the temperature-dependent volume, bulk modulus and thermal expansion are given, and examples of the use of these equations are provided, with particular emphasis on the light actinides. For the elements, we examine the relationship between experimental values of γ G and δ T, and find no clear correlation. In particular, Swenson's rule, which states that the bulk modulus does not change with temperature if the volume is held constant, is a poor approximation to the data. We reveal a new useful approximate relationship between dB/dP and γ G. We find that the thermodynamic quantity q, which describes the variation in γ G with volume, distributes around 2, not around 1, as often assumed. We show that the thermal- expansion behavior of Si and Ge (including negative thermal expansion at low temperatures) are well described with the use of a two-level invar model. 相似文献
10.
将冲击Hugoniot线作为Grüneisen物态方程的参考线,以冲击的初始状态为参考状态,推导得到线性和二次曲线表示的冲击绝热线所对应的等熵压缩线方程,计算了200 GPa压力范围内铝和铜两种材料的等熵压缩线,并且计算了以Hugoniot关系为基础的Appy经验物态方程导出的等熵压缩线。计算结果表明,以Appy经验物态方程导出的等熵压缩线与以线性冲击绝热线导出的等熵压缩线接近,在200 GPa压力范围内两者相差不到1.5%。将计算得到的铝的等熵压缩线与美国Sandia实验室ICE实验Z864数据进行了比较,由线性Hugoniot得到的等熵压缩线与实验数据相差不到1%,由Appy经验物态方程得到的等熵线与实验数据几乎重合,说明在200 GPa压力范围内,以Appy物态方程和以线性Hugoniot为参考来计算的等熵压缩线有较高的精度。 相似文献
11.
In the present paper, new and useful theoretical methods for the estimation of cohesive energy density (Ced) and isothermal compressibility (kT) of alkali metal halides are described. The mentioned theoretical methods include the use of Kaya molecular hardness equation published by us in recent years. Cohesive energy density and isothermal compressibility of alkali metal halides were calculated in the framework of mentioned theoretical methods and the results obtained were compared with both experimental data and the results of previous theoretical methods proposed to calculate the aforementioned quantities, namely cohesive energy density and isothermal compressibility. It is important to note that the results obtained in the study are in good agreement with the available experimental data and with the results of previous theoretical methods. Additionally, we also investigated the correlation with lattice energy of cohesive energy density and isothermal compressibility for alkali halides. 相似文献
12.
B K Sharma 《Pramana》1991,37(6):489-496
The isochoric temperature derivative of sound velocity, Beyer’s nonlinearity parameter, the isothermal volume derivatives
of thermodynamic Grüneisen parameter and isochoric heat capacity and the repulsive exponent of intermolecular potential are
shown to be related to the molecular constant representing the ratio of internal pressure to cohesive pressure of liquids.
The calculated values are reasonably satisfactory and explain the experimental results on sound propagation data of liquids.
The results have been used to develop further understanding of the significance of molecular constant, fractional free volume
and repulsive exponent of intermolecular potential in describing various thermoacoustic and nonlinear properties and the anharmonic
behaviour with regard to molecular order and intermolecular interactions in liquids. 相似文献
13.
Abstract Isobaric heat capacities of liquid n-dodecane were measured at temperatures from 313.15 to 373.15 K and at pressures up to 100 MPa using a calorimetric device based on a Calvet calorimeter (Setaram (280). These experimental data were used to perform a comparative study in order to choose, from among the great number of equations of state proposed in the literature, the most appropriate to calculate the isobaric heat capacity. 相似文献
14.
The paper reports accurate measurements of the thermal conductivity of ethane, ethylene, nitrous oxide, air and argon-free air as a function of density at a temperature of 27.5°C. In the case of ethane the experimental data extend over the pressure range 0.6–3.4 MPa, for ethylene over the range 0.6–5 MPa and for nitrous oxide over the range 0.6–4.5 MPa. The measurements on the two samples of air cover the range 0.8–36 MPa. All the measurements have been carried out in a transient hot-wire instrument and have an estimated uncertainty of ±0.2%.For air the few experimental data that exist deviate by up to 5% from the present results which are to be preferred owing to their higher accuracy. In the case of the pure gases the experimental data are combined with accurate viscosities and employed to estimate collision numbers for rotational relaxation in the gases. 相似文献
15.
Thermal conductivity and thermal diffusivity of tantalum in the temperature range from 293 to 1800 K
Thermal diffusivity of polycrystalline tantalum at the temperature range from 293 to 1800 K has been measured by the laser
flash method with the error of 2–4 %. Thermal conductivity has been calculated with the use of reference data on density and
heat capacity. Approximating equations and tables of reference data for the temperature dependence of heat transfer coefficients
have been obtained; comparison with the published data has been carried out.
The work was financially supported by the Russian Foundation for Basic Research (Grant No. 07-08-00071). 相似文献
16.
17.
根据激光二极管纵向抽运Tm,Ho:YLF激光器的能级跃迁和能量传递过程,在考虑能量传递上转换和基态重吸收的前提下,建立了准三能级速率方程理论模型.给出了Tm,Ho:YLF激光器的热转换系数的解析表达式,讨论了抽运光斑半径与激光束腰半径的比值对热转换系数的影响.实验上得到了热焦距随抽运功率的变化关系,并将其与理论结果进行了对比,发现符合较好.
关键词:
Tm
Ho:YLF晶体
能量传递上转换
速率方程
热转换系数 相似文献
18.
In the present study, a novel method is proposed to accurately calculate the thermal expansivity of semiconductors using the analytical expression obtained for the integer and non-integer n-dimensional Debye functions. The proposed approach is novel as it uses the non-integer n-dimensional Debye functions for the accurate calculations of the thermal expansivities of semiconductors. As an example of the application, the calculation is performed for the thermal expansivities of the Si and Ge semiconductors. Analysis using computer simulation proved that the formula was in excellent agreement with the results reported in the literature. 相似文献
19.
20.
The effect of normal scattering processes is considered to redistribute the phonon momentum in (a) the same phonon branch
— KK-S model and (b) between different phonon branches — KK-H model. Simplified thermal conductivity relations are used to
estimate the thermal conductivity of germanium, silicon and diamond with natural isotopes and highly enriched isotopes. It
is observed that the consideration of the normal scattering processes involving different phonon branches gives better results
for the temperature dependence of the thermal conductivity of germanium, silicon and diamond with natural and highly enriched
isotopes. Also, the estimation of the lattice thermal conductivity of germanium and silicon for these models with the consideration
of quadratic form of frequency dependences of phonon wave vector leads to the conclusion that the splitting of longitudinal
and transverse phonon modes, as suggested by Holland, is not an essential requirement to explain the entire temperature dependence
of lattice thermal conductivity whereas KK-H model gives a better estimation of the thermal conductivity without the splitting
of the acoustic phonon modes due to the dispersive nature of the phonon dispersion curves.
相似文献