用局部组成理论关联纳米流体的剪切黏度

In this study, a new method is presented to correlate the shear viscosity of nanofluids by local composition theory. The Eyring theory and nonrandom two-liquid (NRTL) equation are used for this purpose. The effects of temperature and particle volume concentration on the viscosity are investigated. The adjustable parameters of NRTL equation are obtained by fitting with experimental data. The calculated shear viscosities for nanofluids of CuO/water with 29 nm particle size, Al2O3/water with two different particle diameters, 36 nm and 47 nm, and CuO/(ethylene glycol, water) are compared with experimental data and the average absolute deviation (AAD) is 1.2%, while the results from some conventional models yield an AAD of 190%. The results of this study are in excellent agreement with experimental data.     

转盘式萃取塔有效扩散系数的预测及其在设计中的应用

A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally under different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effective diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.     

借助变阱宽方阱链流体状态方程模拟非电解质体系表面张力和粘度(英文)

The equation of state(EOS)for square-well chain fluid with variable range(SWCF-VR) developed in our previous work based on statistical mechanical theory for chemical association is employed for the correlations of surface tension and viscosity of common fluids and ionic liquids(ILs).A model of surface tension for multi-component mixtures is presented by combining the SWCF-VR EOS and the scaled particle theory and used to produce the surface tension of binary and ternary mixtures.The predicted surface tensions are in excellent agreement with the experimental data with an overall average absolute relative deviation(AAD)of 0.36%.A method for the calculation of dynamic viscosity of common fluids and ILs at high pressure is presented by combining Eyring’s rate theory of viscosity and the SWCF-VR EOS.The calculated viscosities are in good agreement with the experimental data with the overall AAD of 1.44% for 14 fluids in 84 cases.The salient feature is that the molecular parameters used in these models are self-consistent and can be applied to calculate different thermodynamic properties such as pVT,vapor-liquid equilibrium,caloric properties,surface tension,and viscosity.     

利用最大泡压法研究扩散控制的溶液表面吸附动力学

In studying the diffusion-controlled adsorption kinetics of aqueous surfactant solutions at the air/solution surface by means of the maximal bubble pressure method, Fick's diffusion equation for a sphere should be used. In this paper the equation was solved by means of Laplace transformation under different initial and boundary conditions. The dynamic surface adsorption (t) for a surfactant solution, which was used to describe the diffusion-controlled adsorption kinetics at the solution surface, was derived. Different from the planar surface adsorption, the dynamic surface adsorption (t) for the short time consists of two terms: one is the same as WardTordai equation and the other reflects the geometric effect caused by the spherical bubble surface. This effect should not be neglected for the very small radius of the capillary. The equilibrium surface tension γeq and the dynamic surface tension γ(t) of aqueous C10E6 [CH3(CH2)9(OCH2CH2)6OH] solution at temperature 25°C were measured by means of Wilhelmy plate method and maximal bubble pressure method respectively. As t → 0, the theoretical analysis is in good agreement with experimental results and the dependence ofγ(t)on(√t r0/√πD)2 is linear.     

一个基于NRTL方程的液体混合物表面张力模型

A new equation for predicting surface tension is proposed based on the thermodynamic definition of surface tension and the expression of the Gibbs free energy of the system. Using the NRTL equation to represent the excess Gibbs free energy, a two-parameter surface tension equation is derived. The feasibility of the new equation has been tested in terms of 124 binary and 16 multicomponent systems(13-ternary and 3-quaternary) with absolute relative deviations of 0.59~0 and 1.55~0 respectively. This model is also predictive for the temperature dependence of surface tension of liquid mixtures. It is shown that, with good accuracy, this equation is simple and reliable for practical use.     

空化流中空穴的溃灭强度和诱导的自由基浓度

Enhancing the chemical reaction processes by means of the energy released in the collapse of micro bubbles or cavities in the cavitation flow is a new research area. In the previous work, a new approach of measuring concentration of free hydroxyl radicals induced in cavitation flow by using methylene blue as the indicator was developed and used to study concentration of free radical induced in Venturi cavitation flow under various experimental conditions. In the present research, the radial evolution of a cavity bubble and the corresponding collapse pressure in sonic cavitation field are obtained by solving three different bubble dynamics equations： Rayleigh equation, Rayleigh-Plesset equation and Gilmore equation. By comparing with the experimental data on the radial evolution of a cavity bubble in the literature, it is found that the predicted results by the Gilmore equation, which takes account of the compressibility of fluid in addition to the viscosity and interfacial tension, agree with the experimental ones better than those by other two equations. Moreover, the theoretically predicted collapse pressures are consistent with the concentration of the free hydroxyl radical induced in the experimental venture. Thus, the concentration of the liberated free hydroxyl radical not only influences the reaction rate but also is used as an available parameter for measuring collapse intensity of cavities.     

Measurement and modeling of vapor-liquid equilibrium for ternary system water + 2-propanol + 1-butyl-3-methylimidazoliumchloride简

Vapor-liquid equilibrium （VLE） data for water ＋ 2-propanol ＋ 1-butyl-3-methylimidazolium chloride （[bmim]Cl） were measured. Six sets of complete T, x, y data are reported, in which the 2-propanol mole fraction on IL-free basis is fixed separately at 0.1, 0.2, 0.4, 0.6, 0.8, and approximate 0.98, while the IL mass fraction is varied from 0.1 to 0.8, in an interval of 0.1. The non-random-two-liquid （NRTL） and electrolyte non-random-two-liquid （eNRTL） equations are used to correlate the experimental data with satisfactory results. The ternary VLE behavior is also modeled with the parameters obtained by correlating two data sets, in which the mole fraction of 2-propanol on IL-free basis is approximately 0.1 and 0.98. In this way, the six sets of data are reproduced satisfactorily. With the eNRTL model, the root-mean-square deviation for temperature is 0.82 K and that for vapor-phase mole fraction is 0.0078. The influences of IL on activity coefficients and relative volatility of the volatile components are also graphically illustrated.     

Tao-Mason状态方程扩展用于重正烷烃(英文)

In our previous paper we extended the Tao and Mason equation of state (TM EOS) to refrigerant fluids, using the speed of sound data. This is a continuation for evaluating TM EOS in predicting PVT properties of heavy n-alkanes. Liquid density of long-chain n-alkane systems from C 9 to C 20 have been calculated using an analytical equation of state based on the statistical-mechanical perturbation theory. The second virial coefficients of these n-alkanes are scarce and there is no accurate potential energy function for their theoretical calculation. In this work the second virial coefficients are calculated using a corresponding state correlation based on surface tension and liquid density at the freezing point. The deviation of calculated densities of these alkanes is within 0.5% from experimental data. The densities of n-alkanes obtained from the TM EOS are compared with those calculated from Ihm-Song-Mason equation of state and the corresponding-states liquid densities (COSTALD). Our results are in favor of the preference of the TM EOS over other two equations of state.     

Solid-Liquid Equilibria of Several Binary and Ternary Systems Containing Maleic Anhydride

Solid-liquid equilibria (SLE) of three binary systems and seven ternary systems containing maleic an-hydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources, dortmund data bank(DDB), if there's any, and correlations based on our former presented experimental SLE data of twenty binary systems. New groups of MA, ACCOO group, COO group, >C=O group and cy-CH2 group are defined and the SLE data of rnaleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters, correlated with Wilson equation and the λh equation. The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing rnaleic anhydride.     

顺丁烯二酸酐在单一溶剂和混合溶剂中的固液平衡研究

Solid-liquid equilibria (SLE) of three binary systems and seven ternary systems containing maleic anhydride(MA) are measured by visual method. The experimental data are compared with the calculated ones with modified universal quasichemical functional group activity coefficient(UNIFAC) method in which the interaction parameters between groups come from two sources, dortmund data bank(DDB), if there’s any, and correlations based on our former presented experimental SLE data of twenty binary systems. New groups of MA, ACCOO group, COO group, ＞C=O group and cy-CH2 group are defined and the SLE data of maleic anhydride in isopropyl acetate in literature are cited in order to assess the new interaction parameters, correlated with Wilson equation and the λh equation. The modified UNIFAC method with these new regressed interaction parameters is also used to predict other three binary systems containing maleic anhydride.     

K2NiF4型Pr2-xSrxCoO4±λ的合成及催化氧化活性

采用聚乙二醇凝胶法合成了Co系稀土复合氧化物Pr_2-xSr_xCoO_4±λ（0.2≤x≤1.0）,以CO和C₃H₈氧化为探针反应及XRD、TPD、TPR、XPS和化学分析等方法对催化剂的组成、结构进行了表征.结果表明：所有样品都具有K₂NiF₄型结构,x=0.2和x=1.0时,样品中有少量杂相,0.2＜x＜1.0时,样品为单一A₂BO₄物相;随x的增大,Pr_2-xSr_xCoO_4±λ催化剂的晶胞参数、晶胞体积和平均晶粒度递减,晶格畸变率、Co³⁺的含量、晶格氧的脱附量及氧空位浓度递增;x＝0.2和x=0.4时,Pr_2-xSr_xCoO_4±λ催化剂的O_1s谱只有结合能在529 eV附近的脱附峰,而x为0.6～1.0时,其O_1s谱呈双峰结构,且结合能在531 eV附近的脱附峰随x增加而增大;CO和C₃H₈氧化反应的催化活性与Co³⁺、晶格氧及氧空位有密切联系.     

La2-xSrxCoO4±λ(x=0～1.0)催化剂的结构及催化性能

采用聚乙二醇凝胶法制备了Co系类钙钛矿La_2-xSr_xCoO_4±λ(x=0～1.0)复合氧化物,研究了系数x对催化剂的结构和催化性能的影响,考察了它们对 CO和C₃H₈的氧化反应活性,并运用XRD、IR、BET、TPD和化学分析等方法对催化剂进行了表征.结果表明：该类复合氧化物具有K₂NiF₄结构,它们的结构和催化性能随系数x不同而变化,其中以LaSrCoO_4-λ催化活性最好,这是由LaSrCoO_4-λ的晶格氧更易移动、Co³⁺离子含量更高,氧空位和反应时化学吸附氧更多所致.     

氨法脱碳系统再生能耗的研究

氨水溶液能够实现较高的CO2脱除率,具备较大的吸收能力,同时能够脱除烟气中SOx和NOx等酸性气体,近年来被认为是具有发展潜力的CO2吸收剂。普遍认为氨法再生过程的反应热能耗可降至26.88kJ.(molCO2)-1,远低于MEA能耗85kJ.(molCO2)-1。文中对比大量文献中的再生能耗数据,分析了其数据可靠性,理论计算和量热计实验测量低温下(35℃)氨水吸收CO2吸收热为60～70kJ.(molCO2)-1,并且随着CO2负载量增大无明显变化;高温下(80℃)初始吸收热热值约为60kJ.(molCO2)-1,随着CO2负载量增大而增大至120kJ.(molCO2)-1,然后再次减小至80kJ.(molCO2)-1。碳酸铵溶液吸收CO2过程吸收热测量实验也证实了氨水吸收CO2过程无法实现26.88kJ.(molCO2)-1低热值。和其他醇胺溶液吸收热热值相比,氨水溶液在降低能耗方面具有一定优势,但是优势不明显。     

环价连接性指数与饱和烃沸点的QSPR研究

In this paper, according to the peak numbers of the nuclear magnetic resonance and the Randic embranchment degree (δi) of carbon atom i, the carbon atom‘s environment valence gi is defined as. gi =(ti δi)/2. The gi reflect the characteristic of each carbon atom, and as well as the conjunction detail of the carbon atom with other carbon atoms. So, the gi could distinguish better the chemical environment of each carbon atom in the molecule than δi. A connectivity index of environment valence (^mS) and its athwart index (^mS‘) are proposed based on the adjacency matrix and the carbon atom‘s environment valence gi. Among them, the ^0S and ^0S‘ include the characteristic and the connectivity of each carbon atom, the ^1S and ^1S‘ reflect the second conjunction between carbon atoms. Based on ^0S‘ and N (the number of carbon atom), a new structural parameter symmetry degree (N∝), is defined as. N∝ =[ (^0S‘s^0Sc‘) N]^2/3, and the N∝ reflect the size of the molecule as well as the symmetry of the molecule.The N∝, ^0S and Rn (the biggest ring‘s edge numbers of cycloalkanes) of 474 saturated hydrocarbons (216 paraffins and 258 cycloalkanes) were calculated and correlated with their boiling points. The best regression equation was obtained as follow: In ( 1056 - Tb ) = 6. 9480 - 0. 1040N∝ - 0. 008689^0S -0. 009614Rn 0. 01998Rm^0.5, n=474, R=0. 9989, F=52627, S=5.63K. The model was checked up by the Jackknife‘s method. It should have overall steadiness and could be used for predicting the boiling point of saturated hydrocarbons.     

三相机械搅拌反应器气液传质

由空气-水、液体石蜡-细颗粒黄沙、石英砂、催化剂构成三相体系,常压下在表观气速0.10×10^-2～1.5×10^-2cm•s^-1 、固体浓度为0～0.34 g•ml^-1溶剂、搅拌转速450～1500 r•min^-1的实验条件下,采用溶氧仪研究了三相机械搅拌反应器的气液传质特性,考察了操作参数和液体性质、颗粒粒径及密度等物性因素对液相容积传质系数k_La的影响,用改进的高斯-牛顿法进行参数估值,得到k_La与上述因素的量纲1关联式,统计检验表明,所得量纲1关联式与实验值拟合情况良好,可为后续搅拌反应釜中三相淤浆床甲醇合成过程分析与模拟提供传质基础数据.     

溴氰菊酯低温热容的测定及热化学性质

采用精密自动绝热量热计测量了溴氰菊酯在80～400 K温区的热容,试样纯度为0.9926（摩尔分数）.在此温区内出现一个固-液熔化相变,其熔化温度T_m、摩尔熔化焓Δ_fusH_m、摩尔熔化熵Δ_fusS_m分别为（372.15±0.02）K,（26.73±0.02）kJ·mol^-1,（71.81±0.06）J·K^-1·mol^-1.报道了该物质在298.15～400 K温区内每隔5 K的热力学函数H_(T)-H_(298.15),S_(T)-S_(298.15),G_(T)-G_(298.15)值.采用DSC法对试样进行了测定,并与绝热量热法进行了比较.用热重法研究了该化合物的热分解行为,得到分解反应动力学参数反应级数n、频率因子A及活化能E分别为1.78,1.15×10⁹min^-1,603.8 kJ·mol^-1.     

降膜蒸发过程熵产分析

从热力学第二定律出发,将普适体系的熵产表达推广于降膜蒸发过程熵产分析并得到熵产计算式.引入单位熵产数并得到Reynolds数大于1450(c_pμ/λ)^-1.06(0.5-0.25ω)^-1情况下和Reynolds数之间的定量关系,据此揭示了降膜蒸发过程熵产随降膜管内液膜厚度减小先降低再增大的规律,对应存在最小熵产数.与φ30×2×6000传热管内磷酸降膜蒸发实验数据对比结果吻合良好,表明本文熵产计算式可以根据过程的热力参数表达降膜蒸发过程的熵产规律,对过程强化和提高热力学效率具有实际指导意义.     

水在ZSM-5型分子筛中吸附的Monte Carlo模拟

构建了ZSM-5型分子筛物理模型,采用Connoly表面方法和Solvent表面方法对ZSM-5型分子筛的几何结构和性质进行了模拟分析。通过巨正则系综蒙特卡罗方法(GCMC)模拟研究了水蒸气在ZSM-5型分子筛上的吸附特性。通过模拟方法看到了实验难以表征的水蒸气在分子筛中具体吸附位,研究了压力、温度和硅铝比对ZSM-5型分子筛吸附性能的影响及其吸附热的变化规律。     

铁氧体催化剂磁性合成及其对双氧水分解反应的影响

通过双氧水催化分解反应动力学研究,显示磁化合成铁氧体具有较高的催化速率.利用高分辨分析电镜和电子能量损失谱测试了其显微形貌、化学组成和微区晶体结构,探讨了催化作用机理.     

The X-ray structure of (MeBm2t)1-cyclosporin complexed with cyclophilin A provides an explanation for its anomalously high immunosuppressive activity

For most of the cyclosporin A (CsA) analogs, there is generallya good correlation between cyclophilin binding and immunosuppression.However, this relationship does not seem to hold for 4-[(E)-2-butenyl]-4,4,N-trimethyl-L-threonine¹(MeBm₂t)¹-CsA.Its affinity for cyclophilin was reported to be {small tilde}1percent; that of CsA and its immunosuppressive activity invitro was shown to be {small tilde} 30% that of CsA. We reporthere the crystal structure of a complex between recombinanthuman cyclophilin A (CypA) and (MeBm₂t)¹-CsA which has beendetermined by X-ray crystallography at 2.2 Å resolutionand refined to an Rfactor of 16.3%. (MeBm₂t)¹-CsA shows a similarbound conformation and network of interactions to CypA as CsA.The measured lower affinity for CypA cannot therefore be explainedby a different mode of binding. We propose that the poor affinityto CypA could be accounted for by the existence of an equilibriumin aqueous solution between a ‘cyclophilin bound conformation’and a ‘nonbinding conformation’ of (MeBm₂t)¹-CsA.The relatively high immunosuppressive activity is suggestedto result from slight conformational differences observed inthe effector domain