共查询到19条相似文献,搜索用时 233 毫秒
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采用状态方程和多项式函数拟合两种方法,利用现有的物性计算,提出一些常用制冷剂的热力性质计算公式。利用FORTRAN和VB6.0建立了包含R12、R22、R134a的热物性计算软件。程序开发中采用层次模块的思想和开放式结构,便于增加新的制冷剂,具有良好的可扩充性。 相似文献
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一个HFC-134a的专用状态方程 总被引:3,自引:0,他引:3
一、问题的提出 HFC-134a是CFC-12的一种很有希望的替代物,对它的热力性质进行深入的研究非常必要,特别是状态方程的研究尤为重要,它是热力学参数计算的重要基础与依据。 评价一个状态方程的好坏,在于它的适用范围、再现不同相区PVT及导出量的精度以及使用的方便性。近几年国内外陆续发表了一些HFC-134a状态方程,其中主要包括日本的C.C.Piao等,美国的D.P.Wilson等,以及哈工大赵鸿斌等发表的方程。这 相似文献
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1引言R134a作为一种新工质,有关对其迁移性质的研究目前还进行的不多,已有的迁移性质计算公式适用范围亦不宽。这些都影响了系统的优化设计和动态仿真。针对这一问题,作者在本文对R134a的导热系数、粘度关系式进行了研究。2有关R134a导热系数、粘度系数的实验研究国内外公开发表的有关R134a导热系数、粘度系数实验研究的报告如表1和表2所示。表1近年来对R134a导热系我实验研究表2近年来对R134a粘应的实验研究本文曾于1996年10月在武夷山召开的中国工程热物理学会工程热力学与能源利用学术会议上宣读.表1、表2列出了各研究者对R134a迁… 相似文献
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HFC—32的热力学性质 总被引:5,自引:0,他引:5
1前言HFC-32和其它HFC类物质的混合物被认为是HCFC-22的最有希望的替代物,因此,需要HFC-32的热物理性质。本文提供了一个适用于整个区域的HFC-32状态方程,结合理想气体比热关系式,给出了HFC-32各种热力性质,如:PVT(压力-比容-温度),内能,Helmholtz函数,Gibbs函数,焓,熵,等容比热,等压比热,声速等的计算式。另外,还给出了单独的饱和蒸气压和饱和液密度关联式。2蒸气压方程与饱和液密度方程至今已有多位学者测量过HFC-32的饱和蒸气压,提供了从180K至临界温度的蒸气压测量数据,根据实验中使用的样品纯度… 相似文献
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氦-3状态方程研究进展第一部分:固-液、气-液饱和线以及临界区状态方程 总被引:1,自引:0,他引:1
宽温度和压力范围内的3He详细热力参数数据对进行极低温基础科学研究和制冷特性研究是至关重要的,但至今尚缺乏一个热力学统一的解析形式状态方程来准确描述1K左右到室温300K温区的3He热力学性质.在收集和整理各类研究3He热力性质文献的基础上,总结了3He固-液、气-液饱和线以及临界区状态方程的研究状况.这项工作不仅能为关心3He局部区域性质的研究人员提供总结,而且可为今后开发宽范围的3He热力学状态方程提供参考. 相似文献
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P. P. Bezverkhii V. G. Martynets É. V. Matizen 《Journal of Experimental and Theoretical Physics》2004,99(5):998-1004
We present a new scaled equation of state adequately describing the P-ρ-T data for fluids near the vapor-liquid transition point and compare this equation to the Schofield parametric equation of state. A comparative analysis of the approximation of data for He4, C2H4, and H2O in the critical region shows that both these equations correctly describe the behavior of thermodynamic functions asymptotically close to the critical point. 相似文献
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B. Stoki? B. Friman K. Redlich 《The European Physical Journal C - Particles and Fields》2010,67(3-4):425-438
The critical behavior of the chiral quark-meson model is studied within the Functional Renormalization Group (FRG). We derive the flow equation for the scale-dependent thermodynamic potential at finite temperature and density in the presence of a symmetry-breaking external field. We perform a set of approximations to formulate and solve the FRG flow equation in the presence of fermionic degrees of freedom and test their influence on the O(4) critical properties expected in the quark-meson model. Within this scheme, the critical scaling behavior of the order parameter, its transverse and longitudinal susceptibilities as well as the correlation lengths near the chiral phase transition are computed for vanishing baryon density. We focus on the scaling properties of these observables at non-vanishing external field when approaching the critical point from the symmetric as well as from the broken phase. We confront our numerical results with the Widom–Griffiths form of the magnetic equation of state, obtained by a systematic ε expansion of the scaling function. 相似文献
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《Physica A》1991,179(3):344-377
The paper is concerned with some theoretical and empirical attempts to obtain a unified equation for the thermodynamic properties of fluids that incorporates the nonclassical scaling laws near the critical point and crosses over to a classical analytic equation far away from the critical point. Specifically we investigate to what extent the various proposed crossover models agree with the known theoretical predictions for the universal ratios among the asymptotic and correction-to-scaling amplitudes in the power-law expansions of the thermodynamic properties around the critical point. 相似文献
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B. N. Shalaev 《Physics of the Solid State》2010,52(1):87-90
The critical behavior of a d-dimensional random Ising ferromagnet described in the critical region by the Ginzburg-Landau model with a random temperature
has been considered. The critical temperature dependences of thermodynamic quantities, the equation of state, and the spin
correlation function at the Curie point have been calculated by the renormalization group method. The most profound questions
of the theory of impurity ferromagnets are the problem of universality and the role of the Griffiths singularities. 相似文献
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The effect of gravity on various thermodynamic properties near the gas-liquid critical point has been calculated. Using a
simple equation satisfying scaling requirements, an analytic expression for density profile is obtained, using which the effect
on different thermodynamic properties can be easily calculated. 相似文献
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考虑把一个装满某种内能为E,熵为S的物质的盒子缓慢地向黑洞降落,Bekenstein认为热力学第二定律成立的必要条件为S/E≤2πR(R为盒子的有效半径),而Unruh和Wald认为Hawking辐射的存在保证了广义热力学第二定律的成立,无需条件S/E≤2πR。我们指出:Hawking辐射和S/E≤2πR都无法保证热力学第二定律的成立。我们根据充分的理由提出:引力场会影响物质的态方程。当盒子中装的为辐射时,我们得出了辐射在视界附近时的态方程,它和平直时空的辐射的态方程很不一样。只要将方程中的某个参量加上适当的限制,即可保证热力学第二定律的成立。
关键词: 相似文献
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对体积物态方程v-vc=(R/p)(h-hc)的物理基础进行了讨论。给出了该方程的一个统计力学形式证明,从而给出了方程中物质参数的微观定义,亦即给出了该方程的具体表达式。在R=R(p)假设下,给出了方程中物质参数的热力学表达式,通过分析其与Debye理论下的对应态定律的一致性,证明了该假设的近似合理性,从而也就证明了该方程的成立并不受其建立时所依据的定压比热为常数这一过强条件的限制。进一步地,通过与物质参数热力学表达式常压实验值的比较,指出了单纯的R=R(p)假定存在一定的局限,该局限引起的偏差随温度的升高而增大,在常压下的高温区间,该偏差在20%左右。 相似文献
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Specific features of the structure of the critical state of binary liquid solutions leading to an anomalous behavior of the
Rayleigh line due to a dramatic increase in concentration and density fluctuations are considered. It is shown that an experimental
treatment must deal with two fluctuation regions near the critical point of solvent vaporization. In the first region, one
can achieve a sufficient degree of accuracy by using theories like self-consistent field theory. In the second region, which
is closer to the critical point than the first region, scaling theory of second-order phase transitions may be applied. It
is found that the anomalous behavior of the Rayleigh line associated with kinetic coefficients is determined by the equilibrium
thermodynamic properties and by the radius of fluctuation correlation (rc). A general theory is developed for calculating thermodynamic potentials, especially the chemical potential and its concentration
derivative in the fluctuation region. The results of these calculations are compared with the experimental data briefly described
in the paper.
Translated fromZhurnal Struktumoi Khimii, Vol. 39, No. 4, pp. 655–668, July–August, 1998. 相似文献