The solution of conjugated multiphase heat and mass transfer problems

Three types of conjugated boundary value problems that arise when heat and/or mass are transferred between contiguous phases are analyzed by means of integral equation formulations. The systems are classified according to the type of differential equation that describes the temperature or concentration field in a phase, and systematic methods of solution are illustrated for each type of conjugated system. These include parabolic-parabolic systems, illustrated by a laminar gas/laminar liquid gas absorption problem, and parabolic-elliptic systems of which heat transfer from a thick-walled tube to a laminar flow is an example. The third type, which is more frequently encountered in chemical engineering, involves the conjugation of a partial differential equation with an ordinary differential equation. The temperature distribution in the falling film reactor is examined from this point of view.     

中国鲁北生态工业模式

山东鲁北生态工业系统拥有磷铵-水泥-硫酸联产、海水"一水多用"、盐碱电联产3条联系紧密的产业链,形成了一个资源共享共管的联合企业型的生态工业模式。本文利用工业生态学、系统工程、化学工程等方法对该系统进行定量分析,揭示了系统物质、能量、共生、柔性等方面的特性,建立了一套系统的生态工业分析方法和指标。分析结果表明鲁北已经形成了一个较为成熟的工业生态系统。     

水盐体系汽液平衡的热力学模型研究

水盐体系的相平衡性质是化工单元操作的基础,在化学化工、海洋、地质等领域有着重要的研究价值。国内外许多学者对水盐体系汽液平衡进行了实验和理论的研究,构筑了各具特色的经验和半经验的模型。针对水盐体系,在NRTL理论的基础上,基于水化作用和混合盐假设建立了能够预测混合体系汽液平衡的活度系数扩展模型。通过对21组二元水盐体系和14组混合体系的关联计算,验证了该模型的可行性;同时,该模型可以采用二元体系参数直接预测计算混合水盐体系汽液平衡。     

Application of Computers in Chemical Reaction Systems

During the last decade digital computers have had a tremendous impact on the computational aspects of the various disciplines of physical sciences and engineering. In the field of catalysis and chemical kinetics computers have proved to be a valuable tool in both research and engineering applications. In most chemical reacting systems the number of reactions proceeding simultaneously is large. Manual calculations for such systems become cumbersome when more than three or four reactions are involved. Usually these reactions are accompanied by thermal effects, and often diffusional and hydrodynamical flow considerations are important [1–3]. The free radical reactions invariably include many simultaneous reactions, and the computer becomes a logical tool for such applications [4]. Another area of computer applications is the optimum design of chemical reactors where the elaborate mathematical optimization procedures are superimposed on the already complex chemical reaction system [5].     

Application of Computers in Chemical Reaction Systems

During the last decade digital computers have had a tremendous impact on the computational aspects of the various disciplines of physical sciences and engineering. In the field of catalysis and chemical kinetics computers have proved to be a valuable tool in both research and engineering applications. In most chemical reacting systems the number of reactions proceeding simultaneously is large. Manual calculations for such systems become cumbersome when more than three or four reactions are involved. Usually these reactions are accompanied by thermal effects, and often diffusional and hydrodynamical flow considerations are important [1-3]. The free radical reactions invariably include many simultaneous reactions, and the computer becomes a logical tool for such applications [4]. Another area of computer applications is the optimum design of chemical reactors where the elaborate mathematical optimization procedures are superimposed on the already complex chemical reaction system [5].     

双相不锈钢的发展、性能与应用(一)

双相不锈钢,由于具有很高的机械强度和优异的耐腐蚀性能,已逐渐地被承认与接受。它不仅应用在有发生应力腐蚀破裂危险的环境里,而且也已应用在越来越多的,诸如油气、石化、化工、造纸、海水系统、化学运输船和建筑等其他的领域里。至今为止,双相不锈钢在国外已开发使用了近六、七十年。特别是最近几十年来,对双相不锈钢的研究、开发工作更是活跃,使得双相不锈钢的应用量也越来越大。22％铬型双相不锈钢的销售量以每年百分之二十的速度增长。UNS31803(2205)型双相不锈钢已占目前全部不锈钢使用量的第三位。     

Evaluation of Covariance Matrix Adaptation Evolution Strategy,Shuffled Complex Evolution and Firefly Algorithms for phase stability,phase equilibrium and chemical equilibrium problems

Phase equilibrium calculations and phase stability analysis of reactive and non-reactive systems play a significant role in the simulation, design and optimization of reaction and separation processes in chemical engineering. These challenging problems, which are often multivariable and non-convex, require global optimization methods for solving them. Stochastic global optimization algorithms have shown promise in providing reliable and efficient solutions for these thermodynamic problems. In this study, we evaluate three alternative global optimization algorithms for phase and chemical equilibrium calculations, namely, Covariant Matrix Adaptation-Evolution Strategy (CMA-ES), Shuffled Complex Evolution (SCE) and Firefly Algorithm (FA). The performance of these three stochastic algorithms was tested and compared to identify their relative strengths for phase equilibrium and phase stability problems. The phase equilibrium problems include both multi-component systems with and without chemical reactions. FA was found to be the most reliable among the three techniques, whereas CMA-ES can find the global minimum reliably and accurately even with a smaller number of iterations.     

On the use of the imperfect tracer pulse method for determination of hold-up and axial mixing

The imperfect pulse method is a powerful technique for experimental analysis of chemical engineering flow systems. The authors have employed this method in studies of holdup and mixing in gas-liquid fluidized beds. In the present paper are discussed two problems connected with reduction of the experimental data obtained in such studies. Tailing is a phenomenon that may seriously affect the accuracy of mixing coefficients determined by the imperfect pulse method. Accurate methods of data reduction, based upon analysis of moments, have been developed, and their applicability is demonstrated by analysis of experimental data. Interphase transfer of tracer material is of particular importance in investigations of gas phase mixing in a gas-liquid system where absorption of tracer gas into the liquid phase normally takes place. A semiempirical method is described for correction of the experimental data in such cases.     

可持续发展的挑战与过程系统工程的机遇

可持续系统是一种全局性的系统工程,按规模大小可分为4个层次:全球性的系统,地理边界为特征的系统,局部的或分布的业务系统,可持续发展技术。本文从这4个层次上探讨了可持续发展带来的挑战。今后任何工业过程,包括化学工程,不可能再作为一个孤立的对象来对待,必须考虑工业过程、人类社会及生态环境的交互作用。过程系统工程处于独特位置,最适合把各学科的成果汇集到一个系统工程框架中,来应对这种挑战。     

化工仿真培训系统

借助计算机,应用化工仿真培训系统来描述化工过程。硬件包括两套仿真系统,软件由系统软件、仿ＤＣＳ软件、典型的化工单元与装置级软件构成     

Information-thermodynamic principle of the organization of chemical engineering systems

The information entropy-based quantitative interpretation of Roullier’s evolutionary law of the system organization of organisms is given as applied to chemical engineering systems. The relationships characterizing the optimal distribution of expenses on the organization of objects were derived for multipurpose processes and multiroute systems from the viewpoint of creating a highly organized chemical engineering system.     

Machine learning for molecular thermodynamics

Thermodynamic properties of complex systems play an essential role in developing chemical engineering processes. It remains a challenge to predict the thermodynamic properties of complex systems in a wide range and describe the behavior of ions and molecules in complex systems. Machine learning emerges as a powerful tool to resolve this issue because it can describe complex relationships beyond the capacity of traditional mathematical functions. This minireview will summarize some fundamental concepts of machine learning methods and their applications in three aspects of the molecular thermodynamics using several examples. The first aspect is to apply machine learning methods to predict the thermodynamic properties of a broad spectrum of systems based on known data. The second aspect is to integer machine learning and molecular simulations to accelerate the discovery of materials. The third aspect is to develop machine learning force field that can eliminate the barrier between quantum mechanics and all-atom molecular dynamics simulations. The applications in these three aspects illustrate the potential of machine learning in molecular thermodynamics of chemical engineering. We will also discuss the perspective of the broad applications of machine learning in chemical engineering.     

电解质溶液热力学进展

本文从工程应用的角度出发,综述了近年来电解质溶液热力学的理论、活度系数的半经验模型及各类相平衡计算方法。讨论了化工界较为关心的含盐溶液汽液平衡关联和预测的进展问题。     

聚焦结构、界面与多尺度问题,开辟化学工程的新里程

20世纪90年代以来,随着计算机技术和测量仪器的迅速发展,化学工程的研究水平日益提升,由经验规则的判断逐渐提高到计算机模拟量化分析. 化学工程的研究范围也日益扩大,下至纳微尺度结构与界面的观察与量化,上至宏观尺度设备与工厂的系统集成. 化学工程的服务对象也由化学工业扩展到冶金、材料、能源、环境、生物等诸多进行物质转化的过程工业. 目前化工科技界正在呼吁寻求继第一里程单元操作、第二里程传递过程和化学反应工程之后的第三里程. 化学工程中以往惯用的忽视非均匀多尺度结构和界面存在的平均方法是造成预测偏差和调控、放大困难的主要原因. 必须关注结构、界面和多尺度问题,研究多尺度结构、界面的量化预测理论和优化调控方法,建立多尺度结构、界面与"三传一反"的关系模型,与当代先进的计算方法、计算流体力学和计算机模拟相结合,有望解决化工过程与设备的优化调控与放大的难题,成为化学工程发展的新里程.     

Methodische Entwicklung verfahrenstechnischer Prozesse

Methodological development of chemical engineering processes . The development of complex systems is especially dependent upon methodologically structured procedures to provide a clear-cut framework for the application of specialist knowledge and creativity and to develop and exploit the field of possible solutions in order to single out a powerful solution. The method of choice should always be systems engineering. It provides, in relatively abtract and interpretable manner, principles, methods, and proven aids in the form of a system concept, a systems engineering plan of procedure, and project management. A brief introduction to the system concept is followed by application of the systems engineering procedural model to process development. Safety engineering and data acquisition are then considered in detail. Heuristic models are also considered in relation to data acquisition. Expert systems are recommended for setting up collections of information. The article closes with a survey of computer-aided process development.     

Integrated design of flexible chemical processes,devices, and control systems

Methodology of designing flexible chemical engineering processes, apparatuses, and systems, which form prerequisites of efficient process control and automation was proposed, and the multistage iteration procedure of solving the problems of the integrated design of flexible automated chemical engineering systems (CESs) was formalized. A method of calculating the structural parameters and regime variables (optimal tasks for the controllers of a system of automatic stabilization (SAS)) that provide the optimal (from the viewpoint of energy- and resource saving and product quality) and safe operation of chemical engineering processes, apparatuses, and systems for the technological equipment implementation of chemical engineering systems has been developed.     

Was leistet die statistische Thermodynamik für den Verfahrens-Ingenieur?

What does statistical thermodynamics do for the chemical engineer? Statistical thermodynamics introduces molecular properties of a particular system into model equations for the thermodynamic functions of fluid mixtures. It thus contributes to the prediction, extrapolation or estimation of fluid properties, in particular phase and reaction equilibria, which are fundamental to numerous processes in thermochemical engineering. For systems of small, rigid molecules, as frequently encountered in natural gas and refrigeration applications, this method has reached a high level that is beginning to be introduced into industrial practice. For systems of complicated organic molecules, models from molecular thermodynamics have firmly established themselves in industrial applications.     

基于工程教育专业认证的化工系统课程群教学体系的构建

基于工程教育专业认证中关于培养学生解决复杂工程问题能力的要求,西北大学化工学院构建和完善了化工系统主干课程群的教学体系。文章通过分析、梳理和总结西北大学化工学院当前化工系统课程体系教学现状及存在的问题,结合工程教育专业认证的教育产出理念,构建了化工系统课程群持续改进的闭环体系,并在教学中付诸实施。