萃取精馏过程的非平衡态热力学分析

对萃取精馏过程进行了非平衡热力学分析,提出了分离过程得以进行的判据.推导出了熵产生的数学表达式,并可将其用于萃取精馏过程的节能分析.此项研究结果只适用于萃取精馏板式塔,且在非平衡热力学的线性区域内     

液体火箭发动机燃烧稳定性非线性理论

初步建立液体火箭发动机燃烧稳定性非线性场振子模型、均匀反应器声振模型、声学模式非线性相互作用模型和非平衡热力学模型, 分析了化学动力学激发的燃烧不稳定现象的规律. 分析表明: 高的活化能不利于燃烧稳定性; 燃气向周围环境的传热是重要的Hopf分岔参数; 燃烧室声学模式之间存在竞争与合作关系; 从非线性非平衡热力学可以推导出燃烧稳定性的热力学判据. 分析结果说明化学动力学是燃烧不稳定的重要激励机理.     

非平衡定态化学反应体系对细致平衡偏离的不可逆性之随机热力学量度

在随机描述的层次上,成功地构筑了非平衡定态化学反应体系对细致平衡偏离的不可逆性之随机热力学判据.基于Fokker-Planck方程建立了连续Markov过程系统的随机熵平衡方程,发现在随机态空间中随机熵的时间变率亦可分为源项和流项两部分贡献.对于化学反应体系,作为态空间源项的随机熵产生可作为偏离细致平衡不可逆性的合适度量,此泛函量的零值标志着细致平衡.进一步借助按系统广度量的Ω展开法,通过对随机力及共轭的随机流的分析揭示态空间中的随机熵产生仅源于状态对细致平衡的偏离,并主要来自非Poisson涨落的贡献,因而可作为随机热力学量去判别和量度化学反应体系对细致平衡的偏离.     

酯化反应精馏体系的相平衡计算

１前言由于反应精馏过程需同时遵循质量作用定律和分离原理,过程影响因素复杂,用数学模拟的方法对其过程进行研究己成为一种重要的方法。为求解模型方程必然涉及到一些基础数据的计算,如求解平衡级模型ＭＥＳＨＲｎｇ组（物料衡算Ｍ方程、热量衡算Ｈ方程、相平衡Ｅ方程、组分归一Ｓ方程及反应动力学Ｒ方程）的过程中,会遇到相平衡常数、烩值等热力学性质的计算;在求解非平衡级模型ＭＥＲＱｉｅ组（物料衡算Ｍ方程、热量衡算ＥＡＮ。传递速率Ｒ方程吸界面相平衡Ｑ方程）的过程中,会遇到传质系数、传热系数、有效相界面积等传递性质的计…     

非平衡热力学在界面传递过程中的应用

21世纪以来，随着各学科之间的交叉渗透，化学工程的研究对象越来越复杂，界面传递对多相化工过程的影响越来越显示出它的重要性，传统的传递模型已经很难对界面复杂动态的传递行为进行定量描述．本文应用线性非平衡态热力学理论，对传统物质传递模型进行描述，分析界面传递过程速率，强化的三个因素：界面传质系数K、传递截面积A、界面化学位梯度△u．以含钾化合物作为模型体系，基于非平衡热力学原理建立了描述和预测固一液界面处介质传递速率的模型，并建立了描述其溶解速率的通用模型和测定钾离子动力学数据的实验方法，通过分析探讨了多相过程速率强化的途径．     

有机溶剂脱水的相平衡研究

根据精馏分析原理可知用精馏的方法不能获得含水量低于7%的有机溶剂,用溶液的热力学处理盐影响恒沸物气液平衡的数据,证实了加入无水氯化钙使有机溶剂脱水是有效的.文章讨论了无水氯化钙脱水的机理,并提出了有机溶剂脱水的合适工艺.     

氯参与的化学气相淀积金刚石的热力学分析

用非平衡热力学耦合模型研究了金刚石在CHCl体系中的生长,计算所得CHCl体系的金刚石生长的相图与大量实验结果符合良好.通过热力学分析讨论了氯的添加对提高金刚石薄膜生长速率及其质量的影响以及降低淀积温度的作用.     

离子液体捕集二氧化碳非平衡热力学研究方法学探讨

介绍了应用非平衡热力学研究离子液体捕集二氧化碳（CO2）动力学的思路，分析了其成功应用需解决三大关键科学难题，即可靠的热力学模型，界面传递速率描述以及准确的通量数据．其中，准确通量数据的获得需要可靠的实验动力学数据和离子液体捕集CO2过程传递面积的有效考察．在此基础上系统地总结了该三大关键科学问题最新的研究进展和分析后续开展的工作，并对离子液体捕集二氧化碳非平衡热力学研究提出展望．     

改进的缔合物模型优化模拟KCl-MgCl2,KCl-FeCl2熔盐体系

改进的缔合物模型中缔合平衡的求解过程被简化,使其能够同时优化更广范围的热力学数据,包括量热、emf和相图等等数据,将其应用于KCl-MgCl2和KCl-FeCl2熔盐体系,从已有的热力学数据优化出合理的溶液模型参数,由该模型推算溶液的热力学性质,结果显示改进的缔合物模型能够很好地描述熔盐体系的非理想性质.     

在非平衡态热力学的基础上探索建立催化理论的新途径

平衡态热力学一直被认作多相催化理论的基石之一.但是,它并不能概括工作中的催化剂的状态和行为,这主要是这里还发生一些非平衡过程.催化体系常常处于非平衡状态之下,而非平衡态条件下体系的状态和行为,同时取决于体系的动力学和热力学.联系动力学和热力学最一般的关系式并非原来的DeDonder不等式:Ar≥0,而是新的De Donder方程ln r/ r=A/RT.同时发生的总反应之间的热力学耦合对总反应的作用只是形式上的,远不及催化反应链中各基元步骤之间在动力学上的耦合那么重要.通过在动力学方程中引入反应亲和力(热力学位)得到的动力学-热力学结合近似分析,可以用来分析非平衡态的催化反应和催化剂状态.非平衡态热力学在建立多相催化理论中,较之原来的平衡态热力学将能提供更能采纳的和更有意义的物理化学背景.     

A thermodynamic interpretation of optimum conditions of the separation of mixture components by distillation of dilute solutions

A condition for the maximum thermodynamic efficiency of distillation of dilute solutions in a multistep cascade was obtained from the condition of a maximum change in the entropy of a mixture. These conditions were shown to correspond to a maximum degree of separation of mixture components. A thermodynamic equation was derived to describe the relation between a decrease in the Gibbs energy and the mixture value increment during distillation of a dilute ideal solution.     

A New Method for Energy-Saving Tray Design

With the enhancement of people's awareness of protecting our resources and environment, it becomes an urgent subject to make effective use of resources and to reduce process energy consumption. Distillation, a major energy-consumption unit operation in chemical process, has been analyzed intensively in terms of entropy generation rate. By using various kinds of thermodynamic analysis methods, chemical engineers have gained many valuable results. These researches, however, merely focused on different technological processes and various process conditions. The effect of tray structural parameter on process entropy generation has largely been neglected.     

Time evolution of the pulsed HF chemical laser system. II. Irreversible thermodynamic analysis

The time rates of change of level populations and radiation densities derived from a detailed kinetic model of the F + H₂ → HF + H laser are employed as input data for a time dependent thermodynamic analysis of this system. The laser is regarded as an irreversible heat engine generating thermodynamic work in the form of laser light. The development in time of the thermodynamic functions, efficiency and irreversible entropy production is determined by computing the contributions of pumping, radiation and relaxation to the entropy and energy of the lasing molecules. Effects of specific rate processes are evaluated by considering different kinetic schemes, i.e. different combinations of kinetic processes and initial conditions. It is shown, among others, that a laser without relaxation processes (“frictionless”) has poor efficiency despite the absence of energy losses and the low irreversible entropy production. On the other hand, the efficiency is high in lasers governed by fast rotational relaxation. This is because rotational relaxation, though leading to some energy losses and irreversible entropy production, compensates for the entropy decrease of the system (while lasing under partially inverted populations) by increasing the bath entropy. The major general conclusion of the analysis is that the thermodynamic constraints related to the kinetic scheme and not the extent of irreversibility of the lasing process is the crucial factor in determining the laser efficiency.     

A Thermodynamic Analysis of Nonequilibrium Argon Plasma Torches

The nonequilibrium process of argon plasma torches is analyzed theoretically. Thermodynamic diagrams of different degrees of ionization are developed to aid in understanding and analyzing the transition from chemical equilibrium to frozen flow in dc plasma torch operations. A thermodynamic model is developed to describe the nonequilibrium processes in a dc argon plasma torch. In the model the ionization process is approximated as a constant-pressure heating process, with little deviation from the equilibrium state upon completion of heating. If the plasma flow is frozen shortly after heating, the entropy increase is small during the transition from equilibrium to frozen flow. In this case the frozen flow will have nearly the same composition and entropy as the flow at the heating section exit. For singly ionized argon plasmas in the entropy range relevant to dc torch operation, the frozen flow solutions on the affinity–pressure diagram are found to be insensitive to entropy change. Therefore the present model predicts that argon plasmas generated at different power levels will have almost identical affinity at the torch exit for the same operating pressure. This prediction agrees with experimental observations except for very low torch power levels.     

反胶束系统及萃取蛋白质的分子热力学模型1: 反胶束系统的分 子热力学模型

以反胶束系统稳定性的热力学分析为基础,综合分析了反胶束系统的三大效应,即低界面张力效应、界面弯矩效应、混合熵效应,提出了一个分子热力学模型,模型所预言的反胶束水分含量随无机盐种类、浓度、表面活性剂浓度以及助表面活性剂含量的变化与所获实验规律定量相符,还能预言反胶束内表面处电势值、表面活性剂解离度。     

用人工神经网络预测催化精馏塔开工过程的研究

催化精馏是使化学反应过程和精馏分离过程结合在一起,是伴有化学反应的新型特殊精馏过程.“反应精馏”概念自20年代提出以来,从30年代到60年代初,研究都是对特定体系的工艺探索;70年代后,研究扩展到非均相催化反应体系,出现了非均相催化精馏过程,成为了反应精馏的一个重要分支;     

Enthalpy–Entropy Compensation Combined with Cohesive Free‐Energy Densities for Tuning the Melting Temperatures of Cyanobiphenyl Derivatives

This work illustrates how minor structural perturbations produced by methylation of 4′‐(dodecyloxy)‐4‐cyanobiphenyl leads to enthalpy–entropy compensation for their melting processes, a trend which can be analyzed within the frame of a simple intermolecular cohesive model. The transformation of the melting thermodynamic parameters collected at variable temperatures into cohesive free‐energy densities expressed at a common reference temperature results in a novel linear correlation, from which melting temperatures can be simply predicted from molecular volumes.     

Phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa

Must distillation processes simulation is a challenging task, due to the lack of thermodynamic interaction parameters and accurate studies of phase equilibria. The presence of polar substances, those different from ethanol and water, and their low concentrations make it very difficult to model industrial distillation. Several of the congeners are essential enological components of the organoleptic matrix. In this work, we are concerned with the study of phase behaviour of ethanol + water + ethyl acetate at 101.3 kPa, this being the third compound, the legal congener of the highest composition in common alcoholic distillation. The experimental results showed partial miscibility and four azeotropes into a complex medium. Group contribution models yield poor results. Disposable literature was compared and commented upon. The lack of experimental data in multicomponent alcoholic distillation mixtures and the low reliability of the group contribution methods suggest a prudent application to process simulation.