统一性溶液理论及其应用

本文基于正规溶液模型和胞腔溶液模型构作了一个称之为统一性的溶液理论，并以此建立了相应的超额Ｇｉｂｂｓ自由能和活度系度数方程。另外，还应用该模型的活度系数方程计算了一些具有代表性体系的汽液平衡，取得很好的结果。     

混合规则在含氨体系相平衡中的应用研究

研究氨+烷烃/氢氟烃体系的相平衡有望解决氨的毒性、可燃性以及与廉价的矿物润滑油的相容性问题,从而拓展氨在制冷领域的应用。本文基于文献数据研究10种混合规则在氨+烷烃/氢氟烃混合物中汽液相平衡的应用,混合规则包括状态方程型混合规则以及活度系数模型与状态方程结合的混合规则,其中简单的VDW混合规则在所有体系中均不能复现实验数据,其它状态方程型混合规则在R.717+R125体系中有较好的拟合和预测效果,而在R717+R1270体系以及R717+R600体系中描述能力都较差。在状态方程与与活度系数模型结合的混合规则中,基于Gibbs自由能、零压力参考态的MHV1、MHV2取得了最好的效果,其中,MHV1在所有研究的体系中均取得最优效果。     

乙二醇／水与丙三醇／水体系的焓浓图与浓图

本文基于乙二醇／水与丙三醇／水两组二元体系在不同温度下的实验数据,对超额焓数据应用局部作用模型拟合,并分析拟合效果与拟合参数变化情况,发现Wilson模型拟合效果较好。通过Wilson方程的活度系数表达形式,推算了两组体系的气液平衡,并进而计算了两组体系的焓浓图与(火用)浓图。     

乙二醇/水与丙三醇/水体系的焓浓图与(火用)浓图

本文基于乙二醇/水与丙三醇/水两组二元体系在不同温度下的实验数据,对超额焓数据应用局部作用模型拟合,并分析拟合效果与拟合参数变化情况,发现Wilson模型拟合效果较好.通过Wilson方程的活度系数表达形式,推算了两组体系的气液平衡,并进而计算了两组体系的焓浓图与(火用)浓图.     

简化的WS混合规则在汽液相平衡中的应用

本文在假定A∞WOS≈[GE/(RT))]EOS' p->0=[GE(x)/(RT)]solution model 的基础上经过一系列的推导,将原WS 混合规则中的交叉相互怍用参数kij简化为一个只与组份和活度系数模型参数有关的函数,并将该简化后的WS混合规则(WS_S)结合PR状态方程及NRTL活度模型对16对双元混合物的汽液相平衡进行了关联。关联结果表明,在较宽的温度与压力范围内,应用该模型可得到令人满意的结果。与原WS混合规则相比,精度基本相当,但是计算量却得到了一定的减小,并使方程具有一定的预测性,可以更加方便地应用于工程设计计算中。     

电解质活度系数的理论计算

本文考虑电解质在混合溶剂中的情况，采用非优先溶剂化观点，并注意到ψ与γ±的关系，通过数学处理，建立了一个两参数（α°，ｈ）的活度系数公式，该式保留了ＳｔｏｋｅｓａｎｄＲｏｂｉｎｓｏｎ活度系数公式的优点，但不包含ψ９且既可适用于单一溶剂体系，又可适用于混合溶剂体系，经过文献２２个体系的处理，表明新建立的公式具有良好的计算精度，所处理的２２个体系的平均相对偏差均小于１％。     

Effects of Calcium Ions on Thermodynamic Properties of Mixed Bilirubin/Cholesterol Monolayers

通过?-A等温线研究了含钙离子浓度不同的水溶液亚相上胆红素/胆固醇混合单分子膜的性质．在此基础上,采用数学方法计算了不同亚相上单分子膜的平均单分子面积、崩溃压、表面压缩系数、超额单分子面积、混合自由能和超额自由能．结果表明,在钙离子溶液亚相上混合单分子膜的结构发生扩张,并且在界面上形成非理想混合单分子膜．与理想混合时相比,这种混合单分子膜在超额单分子面积上表现为明显的正偏差．在纯水亚相上,胆红素与胆固醇的摩尔比为3:2时混合单分子膜为热力学最稳定体系．但是在钙离子浓度逐渐增大的亚相中,这种摩尔比的混合单分子膜热力学稳定性被破坏,即混合单分子膜中的不同组分间自发混合能力下降,这是由于受到钙离子与胆红素和胆固醇之间配位作用的影响．此外,在钙离子溶液亚相中,在较低的表面压下制备出的混合膜具有更好的热力学稳定性．     

高温LiF-NaF-BeF_2熔融体系活度系数和混合焓计算

采用修正的似化学模型和非对称的插值方法对先进反应堆中使用的三元氟化盐LiF-NaF-BeF_2体系的活度系数和混合焓进行了计算,并与修正的McGlashan-Rastogi模型和Harris-Prausnitz模型的计算结果进行了比较。修正的似化学模型计算得到的BeF_2活度系数与实验值的相对偏差绝对平均值为10.7%,好于另外两个模型。三元系活度系数和混合焓的计算结果与边界上的二元系计算结果有较好的连贯性,而且计算值与二元系和三元系的实验数据都吻合较好,表明两种热力学性质是热力学自洽一致的。本文详细计算了LiF-NaF-BeF_2体系在925~1325 K温度区间内的活度系数,当温度升高时,BeF_2活度系数最大值不断减小,对应的BeF_2的含量随之增大。     

一种基团贡献法的非共沸工质气液相平衡模型

本文引入一种基于基团贡献的逸度系数模型来解决常规模型对非共沸混合制冷剂气液相平衡预测精度不足的问题,该模型只使用较少的共性基团参数就能推算大量多元混合物的物性.使用PR状态方程结合vdW混合规则来描述气相逸度、UNI-FAC模型来描述液相逸度.通过对R32+R236fa非共沸混合工质对的气液相平衡饱和蒸汽压力进行计算,并将结果与实验数据、REFPROP 8.0商业软件计算值对比分析.结果 表明:本文模型比REFPROPS.0软件更适应于混合工质;此外,该模型只考虑基团间相互作用,简化了热物性计算.基于提出的模型,绘制了R32+R236fa非共沸混合工质在278.15～363.15 K的相图.     

应用扩展的2CJL模型确定微观势能参数

本文应用扩展的2CLJ势能模型优化了若干线型分子的微观势能参数.该模型包含了二分子间长程静电和诱导作用,同时也考虑了极性分子偶极矩与分子轴不平行的情况.通过第二维里系数的实验数据回归获得简单线型分子N2、O2、Cl2、F2、CO、NO、C2H6和C2F6的硬球直径σ和阱深ε.强极性分子CH3Cl、CH3F、CH3CF3、CF3CH2F和CH3CHF2的第二维里系数运用改进的混合规则计算得到,计算结果与实验数据符合很好.     

地层油气的相平衡热力学研究

地层油气的相平衡热力学研究王利生（北京理工大学化工学院北京１０００８１）关键词混合规则，状态方程，油藏流体，相平衡１链状分子的普遍化范德华配分函数链状分子的转动和振动运动会受阻于其它分子的运动，因而其配分函数中的转动和振动贡献与温度、密度均有关，被分...     

Black holes as collapsed polymers

We propose that a large Schwarzschild black hole (BH) is a bound state of highly excited, long, closed strings at the Hagedorn temperature. According to our proposal, the interior of the BH consists, on average, of a uniform distribution of matter with low curvature and large quantum fluctuations about the average. This proposal represents a dramatic departure from any conventional state of matter and from the longstanding expectation that the interior of a BH should look like empty space except for a very small, dense core (the singularity). Standard effective field theory in terms of the metric and other quantum fields is incapable of describing such a state in a meaningful way. However, in polymer physics, such states can be described by a mean field theory in terms of the polymer concentration. We therefore propose that the interior of the BH be described in terms of an effective free‐energy density which is a function of the string concentration or entropy density; this density being a highly non‐perturbative quantity in terms of the metric and other quantum fields. For a macroscopic BH, our proposed free‐energy density contains only linear and quadratic terms, in analogy with that of the theory of collapsed polymers. We calculate the coefficient of the linear term under the accepted assumption that the dominant interaction of the strings at large distances is the gravitational interaction and the coefficient of the quadratic term by relying on explicit string calculations to determine the rate of interaction in terms of the string coupling. Using the effective free energy, we find that the size of the bound state is determined dynamically by the string attractive interactions and derive scaling relations for the entropy, energy and size of the bound state. We show that these agree with the scaling relations of the BH; in particular, with the area law for the BH entropy. The fact that the entropy is not extensive is a result of having strong correlations in the interior state, and the specific form of the entropy‐area law originates from the inverse scaling of the effective temperature with the bound‐state radius. We also find that the energy density of the bound state is equal to its pressure.     

Broken Replica Symmetry Bounds in the Mean Field Spin Glass Model

 By using a simple interpolation argument, in previous work we have proven the existence of the thermodynamic limit, for mean field disordered models, including the Sherrington-Kirkpatrick model, and the Derrida p-spin model. Here we extend this argument in order to compare the limiting free energy with the expression given by the Parisi Ansatz, and including full spontaneous replica symmetry breaking. Our main result is that the quenched average of the free energy is bounded from below by the value given in the Parisi Ansatz, uniformly in the size of the system. Moreover, the difference between the two expressions is given in the form of a sum rule, extending our previous work on the comparison between the true free energy and its replica symmetric Sherrington-Kirkpatrick approximation. We give also a variational bound for the infinite volume limit of the ground state energy per site. Received: 6 May 2002 / Accepted: 6 September 2002 Published online: 13 January 2003     

A mixing controlled direct chemistry (MCDC) model for diesel engine combustion modelling using large eddy simulation

A mixing controlled direct chemistry (MCDC) combustion model with sub-grid scale (SGS) mixing effects and chemical kinetics has been evaluated for Large Eddy Simulation (LES) of diesel engine combustion. The mixing effect is modelled by a mixing timescale based on mixture fraction variance and sub-grid scalar dissipation rate. The SGS scalar dissipation rate is modelled using a similarity term and a scaling factor from the analysis of Direct Numerical Simulation (DNS) data. The chemical reaction progress is estimated from a kinetic timescale based on local internal energy change rate and equilibrium state internal energy. An optical research engine operating at conventional operating conditions and Low Temperature Combustion (LTC) conditions was used for evaluation of the combustion model. From the simulation results, the effect of SGS scalar mixing is evaluated at different stages of combustion. In the context of LES, the new approach provides improved engine modelling results compared to the Direct Chemistry Solver (DCS) combustion model.     

Length-Scale Dependence of Hydration Free Energy: Effect of Solute Charge

Size and curvature are important determinants of particle wettability, in addition to surface chemistry and texture. Hydration free energy of a nonpolar solute scales with volume for small solutes and with surface area for larger ones. If the solute acquires a surface charge, the scaling regimes can be affected, with size-dependence of the charge playing a critical role. For isolated particles grown at fixed surface charge density, the Born approximation gives scaling of hydration free energy with volume. We consider a distinctly different but practically important scenario, where the charged solute and surrounding counterions are dissolved together. For this process, our molecular simulations demonstrate the electrostatic contribution to the solvation free energy, calculated per unit area of the solute, to be virtually independent of solute size. We explain this behavior in terms of counterion shielding effect on the curvature-dependent solute energy in the dehydrated state, an effect closely balanced by the influence of dielectric screening in water. As a result, for moderate surface charge densities of the solute, the net electrostatic contribution is dominated by counterion solvation, and scales with solute surface area independently of the ionic strength in the solution.     

Properties of a Bound Polaron under a Perpendicular Magnetic Field

We investigate the influence of a perpendicular magnetic field on a bound polaron near the interface of a polar-polar semiconductor with Rashba effect. The external magnetic field strongly changes the ground state binding energy of the polaron and the Rashba spin-orbit （SO） interaction originating from the inversion asymmetry in the heterostructure splits the ground state binding energy of the bound polaron. In this paper, we have shown how the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity, the wave vector of the electron and the electron areal density, taking into account the SO coupling. Due to the presence of the phonons, whose energy gives negative contribution to the polaron＇s, the spin-splitting states of the bound polaron are more stable, and we find that in the condition of week magnetic field, the Zeeaman effect can be neglected.     

任意维l态Woods-Saxon势的精确解

在D维空间下使用完全量子化规则计算了具有离心项的Woods-Saxon势,根据动量积分 (其中 )和Pekeris近似化条件,得到了系统的任意l波Schrödinger方程的解和能谱方程．讨论了束缚态能谱的有关性质．     

任意维l态Woods-Saxon势的精确解

在D维空间下使用完全量子化规则计算了具有离心项的Woods-Saxon势,根据动量积分 (其中 )和Pekeris近似化条件,得到了系统的任意l波Schrödinger方程的解和能谱方程．讨论了束缚态能谱的有关性质．     

Mixing rules and effective potentials in gaseous mixtures

We generate exact mixing rules for dilute gaseous mixtures with nonconformal interactions by introducing an adequate effective potential. The general mixing rule leads to several approximations of the van der Waals type. The work uses nonconformal model pair potentials that accurately describe the pure fluid properties. The validity of the approximate mixing rules is assessed by comparison with exact results for binary mixtures over wide ranges of temperature and composition. Large differences in energy, size and potential profile are considered. The simplest mixing rules are straightforward generalizations of the van der Waals rules and one version, based on a square-well (SW) approximation, performs with high precision for all systems except for those with extreme differences in molecular size. The SW mixing rule is used to predict excess virial coefficients of mixtures involving Ar, Kr, H₂ and CF₄.