共查询到20条相似文献,搜索用时 68 毫秒
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采用Bubnov-Galerkin方法对有恒壁温条件下,两平板间夹有含相变颗粒流体的自然对流热启动瑞利数进行了近似解析求解,求出了临界瑞利数Racr和波频数kcr随相变物质浓度,以及在相变温度范围内随加热表面温度的解析关系表达式.从而,为实现该类功能性潜热流体的自然对流传热强化,及其优化控制蓄热过程有理论指导意义. 相似文献
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研究流体相变及临界现象对今后化学工程的发展有重大意义.由于各种具有临界点的体系在各自 临界点有一些共同的实验特征和极相似的临界现象,而流体的研究在实验上又有独特方便之处,所以可 作为普适性研究将理论及实验结果推广到固体.微重力条件下的流体相变及临界现象研究提供了十分 靠近临界点的最佳实验条件,本文介绍了这方面研究工作的物理意义及进展. 相似文献
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GaAs相变和热力学性质的密度泛函理论研究 总被引:6,自引:4,他引:2
利用平面波赝势密度泛函方法,对GaAs从闪锌矿结构到CsCl 结构的相变进行了理论研究.通过Birch-Murnaghan状态方程拟合闪锌矿结构GaAs的能量和体积,得到了GaAs的热力学性质.我们发现对 GaAs来说,闪锌矿结构通常比CsCl结构稳定,由闪锌矿结构到CsCl结构的相变压力在37.019 GPa左右.计算所得到的晶格常数、体弹模量及体弹模量对压强的一阶导数与实验值以及其他作者的计算值相符合. 相似文献
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利用密度泛函理论的平面波赝势方法预测研究了CaPo从岩盐结构(B1结构)到氯化铯结构(B2结构)的相变以及B1结构CaPo高压下的弹性性质以及热力学性质等.通过等焓原理发现B1→B2的相变压力为22.8GPa. 同时计算了B1结构CaPo高压下的弹性常数以及剪切模量、杨氏模量等相关弹性参数,结果发现当压力超过20GPa时,B1结构CaPo开始不稳定了,这和等焓原理所得结果相符合. 最后通过Debye模型成功获取了B1结构C
关键词:
相变
弹性性质
热力学性质
CaPo 相似文献
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热力参数的对比变换与流体工质热力性质的通用对比方程 总被引:7,自引:2,他引:5
本文提出了判别流体热力学性质的通用对比方程的规则和选择作为通用对比方程的热力学参数对比交换的方法;具体给出了工质饱和液体焓和温度的合适对比变换式和通用对比方程。经检验,该通用方程的计算值与25种常用流体工质的推荐值的平均绝对偏差为0.5%,算术平均偏差为-0.04%。本文的理论纠正了传统的只用临界参数为对比值的片面认识,为建立在无通用对比方程而仅利用合适的参数变换,从一种已知物性物质推算另一种物质未知物性的一般方法和其它物性的通用对比方程奠定了基础。 相似文献
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Analytic expressions for the thermodynamic properties of a classical two-dimensional square-well fluid and the first quantum
correction to them are derived using the Barker-Henderson perturbation theory. Numerical results are reported. It is found
that the quantum effect, which increases with increase of density, is largely determined by the hard-core and the attractive
tail has a minor effect at high density. 相似文献
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H Eugene Stanley 《Pramana》1999,53(1):53-83
Although H2O has been the topic of considerable research since the beginning of the century, the peculiar physical properties are still
not well understood. First we discuss some of the anomalies of this ‘complex fluid’. Then we describe a qualitative interpretation
in terms of percolation concepts. Finally, we discuss recent experiments and simulations relating to the hyothesis that, in
addition to the known critical point in water, there exists a ‘second’ critical point at low temperatures. In particular,
we discuss very recent measurements of the compression-induced melting and decompression-induced melting lines of high-pressure
forms of ice. We show how knowledge of these lines enables one to obtain an approximation for the Gibbs potential G(P, T) and the equation of state V(P,T) for water, both of which are consistent with the possible continuity of liquid water and the amorphous forms of solid water. 相似文献
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The perturbation theory with non-spherical reference system is used for molecular fluid with angle-dependent square-well type
potential. Simple analytic expressions are given for the thermodynamic properties such as the equation of state, excess free
energy per particle, internal energy and internal heat capacity. The effects of anisotropy on the thermodynamic properties
are discussed. The anisotropy effects increase with increase of density and decrease of temperature and depends on the anisotropy
parameterx
0. 相似文献
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Thermodynamic properties of molecular fluid mixtures of hard ellipsoids are calculated. Numerical results are given for equation
of state and excess-free energy of the binary mixture of both additive and non-additive hard ellipsoids. It is found that
the equation of state and free energy of mixtures increase with increase of anisotropy parameterx
0. 相似文献
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G. H. Bordbar S. M. Zebarjad F. Shojaei 《International Journal of Theoretical Physics》2004,43(9):1863-1873
We investigate the liquid–gas second-order phase transition in liquid 3He using the variational calculations based on the cluster expansion of the energy functional. We also compute the critical point exponents of liquid 3He that are in agreement with experimental data. 相似文献
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The nonmetal-to-metal transition in dense fluid helium is discussed, which has been, in analogy to metallization of hydrogen, predicted as first-order plasma phase transition using chemical models for the equation of state and plasma composition. However, recent ab initio simulations performed for dense fluid helium indicate that this transition is continuous in the considered regime, without a density jump and latent heat as characteristic of a first-order phase transition. Implications for some astrophysical plasmas are discussed. 相似文献
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Molar heat capacities were measured on seven mixtures [(1 − x)thiophene + x benzene] using an adiabatic calorimeter in the 14 and 300 K temperature range. The measurements were made at x = 0.0016, 0.0030, 0.0050, 0.0061, 0.0070, 0.0183 and 0.0210, respectively. Transitions between various phases in stable and metastable sequences of thiophene crystal were found to be affected more or less by the benzene doping in this thiophene-rich region. Among others, the II2-II1 transition in the metastablephase sequence was affected drastically by the dopant. The significant effect of benzene on the transitional behavior was discussed in relation to the incommensurate structure of phase II,. Glass transitions observed in phase II1 or II2 were analyzed in terms of the Kohlrausch-Williams-Watts equation to derive kinetic parameters characterizing the relaxation processes. Non-exponential behavior of enthalpy relaxation was discussed in the light of possible distribution of relaxation times in the solid solution. 相似文献