关于单元二相系中的[(μ)/(N)]_(T,p)

无锡市一中的沈瑞清同志及无锡麻纺技校的邵建新同志,滨洲师专的潘怀剑同志分别先后来稿,对我刊87年8期刊登的《　及其在相变过程中的体现》一文中论述的欠妥之处提出了改正意见,认为对于单元二相系必须. 现将这几位同志来稿的有关部分分别摘录如下: 沈瑞清及邵建新来稿指出:“如果认为单元二相系相变过程中　而是大于0,会导致如下的荒谬结论,即两相平衡曲线　形状依赖于系统中两相物质的相对比例.例如,在某一温度T和压强p下,若100克水和100克冰不能达成相平衡,而在同一温度和压强下,199克水和1克冰却有可能达到相平衡.这显然与事实不符,可…     

氢氟烃+润滑油混合物气液相平衡模型

氢氟烃 润滑油体系的气液相平衡性质近年来受到了广泛关注,国际上已有一批相关实验数据发表.本文研究了状态方程法模型描述氢氟烃 润滑油体系气液相平衡性质的适用性,分析了混合规则和溶液模型的影响,针对不同类型的体系建立了相应的相平衡预测模型,较好地再现了多种氢氟烃 POE、BAB润滑油体系的气液相平衡性质.     

纳米流体中气体水合物生成条件

为了研究纳米粒子对制冷剂水合物热力学生成条件的影响,建立了新型纳米流体中制冷剂水合物相平衡热力学模型,理论研究了HFC134a(R134a)气体水合物的热力学生成条件,并用实验验证了模拟结果.结果表明:新型纳米流体中制冷剂水合物热力学相平衡模型能够较好地反映纳米流体中制冷剂气体水合物相平衡特征,相同温度下相平衡最大相对误差为7.3%,平均相对误差为5.3%.     

CH4-TBAB二元水合物的分解热测定

利用可视化高压流体测试系统研究了甲烷-四丁基溴化氨(TBAB)水合物的分解条件,并根据物相平衡数据应用Clausius-Clapeyron方程计算了该水合物的分解热.结果显示: CH4-TBAB共生水合物的相平衡压力的对数与温度的倒数为线性关系,其相平衡压力远低于甲烷水合物的相平衡压力,甲烷的存在提高了TBAB水合物的生成温度.CH4-TBAB共生水合物的分解热远大于纯TBAB水合物的分解热,而且分解热的数值与TBAB的浓度有关.     

CPA方程计算醇+卤代烃体系气液相平衡

醇+卤代烃混合体系,尤其是乙醇、三氟乙醇(TFE)等与卤代烃的混合工质在吸收式制冷、热泵、蒸气动力循环等领域中有着重要的应用.CPA方程可以描述缔合流体的性质,用于含醇类组元的混合体系气液相平衡性质描述.本文首先从纯物质饱和性质实验数据回归得到了CPA方程参数;将CPA方程应用于醇+卤代烃混合体系的气液相平衡计算,采用并比较了2种缔合方案;比较了CPA方程与G~E-EoS模型的相平衡计算效果.CPA状态方程在揭示分子间相互作用的基础上可准确描述醇+卤代烃混合体系的气液相平衡性质.     

湿空气相平衡的分子动力学模拟研究

本文采用分子动力学模拟方法对湿空气两相平衡问题进行了研究.根据气液相平衡理论,建立了湿空气相平衡模型.水分子、空气分子的相互作用分别采用TIP4P势函数和L-J势函数,水分子与空气分子的相互作用采用L-J势函数.模拟中选取的水分子数为5488,空气分子数为512.模拟研究了湿空气相平衡过程两相中各成分的变化规律,模拟发现气液界面处存在空气分子富集现象,其浓度高于气相和液相的.基于此模型可以确定温度、压力等对气相含湿量和液相溶解度的影响.     

高精度气液相平衡实验系统的建立和实验测定

本文搭建了循环法气液相平衡实验系统,介绍了该实验系统的组成,设计了循环法实验系统的实验流程.本实验系统的温度、压力和摩尔组分浓度的测量不确定度分别为5 mK,600 Pa和0.001.使用该实验系统测定了R125和R290纯净物饱和蒸气压,并进一步开展了R125+R290体系的气液相平衡实验研究,给出了该体系在3个温度下的等温气液相平衡实验数据,采用状态方程法相平衡模型对实验数据进行了关联分析,并与文献值进行了比较,结果表明本文实验数据具有较高精度,也说明了实验系统的可靠性.     

湿法烟气脱硫反应三相平衡线的计算

本文基于计算复杂化学平衡的最小G值法,对湿法烟气脱硫系统中SO_2溶于石灰石浆液的过程进行了数学建模,并根据数学模型开发了计算气-液-固三相相平衡线的软件.为了验证计算软件并分析SO_2在石灰石浆液中的溶解特性,分别计算了SO_2溶于纯水的气-液相相平衡、CaCO_3溶于纯水的固-液相相平衡以及SO_2溶于石灰石浆液的气-液-固三相相平衡,最后与SO_2溶于纯水的相平衡计算结果进行了对比分析.计算结果符合相应的溶解规律并与文献中给出的数据基本一致,因此该计算方法可以用来准确计算气-液-固三相反应化学平衡。     

高压流体相平衡的分子热力学模型

本文应用物质分子聚集与解集理论阐述了高压流体相平衡机理并提出了分子聚集型状态方程.应用此方程能精确地描述流体高压下的PVT关系,且用于预测相平衡数据也获得了满意结果.     

二维二元替换式系统的统计理论

本文利用Collins模型研究二维二元替换式晶格系统。计算了系统的自由能,导出了溶解度和温度关系的曲线方程,并利用相平衡条件获得了和三维二元合金相类似的相图。 关键词：     

Influence of chemical disorder on the magnetic behaviour and phase diagram of the FexNi1−x system

In this paper, we calculate the equilibrium phase diagram and the magnetic moment curve for the Fe_xNi_1−x system and simulate their Mössbauer spectra assuming a binomial distribution to reproduce the chemical disorder in these alloys. We also assume that the high-spin/low-spin transition for a central iron atom is governed by the number of nearest neighbours and next nearest neighbours of the iron atoms. The calculated equilibrium phase diagram and the magnetic moment curve are very close to that presented in the literature and the simulated Mössbauer spectra are in excellent agreement with that of their corresponding phases measured in our lab.     

The self-consistent diagram approximation for lattice systems

We apply the self-consistent diagram approximation to calculate equilibrium properties of lattice systems. The free energy of the system is represented by a diagram expansion in Mayer-like functions with averaging over states of a reference system. The latter is defined by one-particle mean potentials, which are calculated using the variational condition formulated. As an example, numerical computations for a two-dimensional lattice gas on a square lattice with attractive interaction between nearest neighbours were carried out. The critical temperature, the phase coexistence curve, the chemical potential and particle and vacancy distribution functions coincide within a few per cent with exact or with Monte Carlo data. Received 18 March 1999 and Received in final form 8 November 1999     

Calculation of Partition Function of QCD at Finite Chemical Potential

In equilibrium statistical field theory, the partition function has fundamental importance. In this paper we propose a direct and general method for calculating the partition function and equation of state of QCD at finite chemical potential. It is found that the partition function is totally determined by the dressed quark propagator at finite chemical potential up to a multiplicative constant. From this a criterion for the phase transition between the Nambu and the Wigner phases is obtained. This general method is applied to two specific cases： the free quark theory and QCD with a model dressed quark propagator having confinement features. In the first case, the standard Fermi distribution at T = 0 is reproduced. In the second case, we apply the conclusion in previous works to obtain the dressed quark propagator at finite chemical potential and find the unphysical result that the baryon number density vanishes for all values of chemical potential. The reason for this result is discussed.     

EOS for a QGP with a temperature and baryon chemical potential dependent bag pressure

We develop an equation of state (EOS) for the quark-gluon plasma (QGP) involving the temperature and baryon chemical potential dependent bag pressure arising due to the entropy and baryon number conservation at the phase boundary together with the Gibbs’ construction for an equilibrium phase transition. We show that the bag pressure thus obtained yields a decreasing behaviour with the increasing baryon chemical potential at a fixed temperature. Further consequences of the modified bag pressure are discussed.     

化学势在钨表面氢平衡浓度计算中的应用

化学势是热力学与统计物理中重要的物理量,能够表征系统中粒子转移的趋势.本文以钨材料表面氢平衡浓度这一实际问题为例,在氢平衡浓度计算过程中逐步引入化学势的概念,通过分析环境氢分子系统和钨表面系统中氢化学势的变化,给出不同温度、压强下钨表面的氢平衡浓度.在热力学与统计物理教学中,通过平衡浓度的计算促进学生对于化学势等概念的学习和深入理解.     

The Gibbs equilibrium conditions applied to the QGP–hadron transition curve

A method is developed to consistently satisfy the Gibbs equilibrium conditions between the quark–gluon and hadronic phase, although each phase has been formulated in separate grand canonical partition functions containing three quark flavours. The sector in the space of thermodynamic variables where the transition takes place is restricted to a curve, according to the phase diagram of QCD. The conservation laws of quantum numbers are also imposed on the transition curve. The effect of the inclusion of the pentaquark states is considered. The data from S+S, S+Ag (SPS) and Au+Au (RHIC) are found to be compatible with the formation of a QGP phase and the occurrence of the chemical freeze-out immediately after crossing the transition line, but the data from Pb+Pb (SPS) are not. PACS 12.40.Ee; 05.70.Fh; 12.38.Mh; 24.10.Pa     

Pseudocritical point on the melting curve of a metastable phase

The possibility of the existence of a limit to which the melting curve can be extrapolated into the metastable region is discussed. The analysis is made for the example of GaSb, for which the stable and metastable phases of the T-P diagram are known. When the melting curve of the high-pressure modification is extrapolated to low pressures, it crosses the curve of complete instability of the disordered phase at a point k. Since the melting curve is a line of equilibrium between two phases, one of which ceases to exist at the point k because the minimum of the thermodynamic potential that corresponds to this phase becomes degenerate, the melting curve terminates at the point k and further extrapolation of the curve is physically meaningless. Pis’ma Zh. éksp. Teor. Fiz. 66, No. 4, 260–262 (25 August 1997)     

基于傅里叶红外光谱的SiO_2基相变储湿复合材料结构分析及性能优选预测

以SiO_2为载体材料、脂肪酸为相变材料制备具有相变调温性能与储湿调湿性能的SiO_2基相变储湿复合材料。采用等温吸放湿法和步冷曲线法测试不同脂肪酸用量的SiO_2基相变储湿复合材料相变调温性能与储湿调湿性能。利用傅里叶红外光谱测试SiO_2基相变储湿复合材料的结构组成,分析SiO_2与脂肪酸的嵌合机理。以SiO_2基相变储湿复合材料的傅里叶红外光谱特征吸收峰作为输入层,以SiO_2基相变储湿复合材料的脂肪酸用量、相对湿度52.89%下SiO_2基相变储湿复合材料吸湿平衡含湿量与放湿平衡含湿量的平均值、SiO_2基相变储湿复合材料从30~15℃降温所需的时间作为输出层,以S型激活函数作为隐含层,利用BE神经网络建立结构参数与综合相变储湿性能的SiO_2基相变储湿复合材料性能优选预测模型。结果表明,SiO_2基相变储湿复合材料中SiO_2与脂肪酸仅为物理嵌合,未发生化学作用;当脂肪酸用量0.079 mol时,所制备的SiO_2基相变储湿复合材料具有最优的综合相变储湿性能,即在相对湿度52.89%下的吸湿平衡含湿量为0.132 3 g·g~(-1)、放湿平衡含湿量0.147 5 g·g~(-1)、平衡含湿量的平均值为0.139 9 g·g~(-1),从30~15℃降温所需的时间为1 305 s;SiO_2基相变储湿复合材料的性能优选预测模型吻合性较好,具有较高的精确度,其预测值与实测值的相对误差为-2.07%和2.45%,可以用于优选预测SiO_2基相变储湿复合材料的储湿调湿性能和相变调温性能。