Three-dimensional modeling of reaction injection molding. II: Application

The objective of this research is to demonstrate the application of a general model of reaction injection molding (RIM) to a complex shaped mold part. Using the fundamental physical and chemical properties of the RIM system, prediction of RIM moldability can be made. The numerical techniques used in this research are presented in a previous paper (1). The rigorous modeling of the transport processes and the dynamics of the filling front for a particular application are described in this work.     

Medizinische Verfahrenstechnik

Chemical engineering aspects in medicine. Many basic chemical engineering processes are based on transport processes due, for example, to differences in temperature, pressure, and concentration. Such transport processes abound in the healthy circulatory system. Thus, metabolic processes supply the human body with the necessary warmth. The heart serves as a blood pump to provide optimal blood pressure in all vessels. Highly complex membranes in the kidneys ensure the efficient detoxification of the blood. It is therefore natural that the chemical engineer be in volved in the solution of a number of biomedical engineering problems that come up in the field of medicine. Some typical tasks are: the characterization of the flow properties of biological fluids; research on the interaction between blood and foreign substances of the purpose of finding materials suitable for temporary or permanent use in the body and the development of blood pumps and artificial substitutes for the lungs, the liver, and the kidneys.     

Applications of in situ magnetic resonance techniques in chemical reaction engineering

NMR spectroscopy is now a well‐established technique for the in situ study of surface chemistry and the chemical processes occurring during catalytic reactions. Developments in probe design are making the sample environments ever closer to the operating conditions of the catalyst in industrial use. In parallel with these advances there is an increasing interest in the application of field gradient magnetic resonance techniques, namely pulsed gradient spin echo (PGSE) NMR and magnetic resonance imaging (MRI), to in situ studies of mass transport processes in catalysts and reactors. An overview of the recent developments in in situ NMR spectroscopy, PGSE NMR and MRI studies in application to catalysis and reaction engineering is presented and the potential of these techniques in the numerical modelling of catalytic processes and reactor design is highlighted. This revised version was published online in August 2006 with corrections to the Cover Date.     

高能化学激光多物理场耦合数值模拟

高能化学激光是利用大量化学物质的原子受激辐射产生发光现象,为了合理解析这种过程,构建了多物理模型耦合计算体系,所构建的数值模拟体系包含了流场-化学场计算模块、光场计算模块和热-结构计算模块。三种物理过程强烈的时间尺度反差给多物理场耦合计算带来了困难,因而提出了非同步多时间尺度耦合策略,使全三维、高分辨率大尺度化学激光的模拟成为可能,以氧碘化学激光为例,数值解析了超音速化学氧碘激光器流动、光场演变及腔镜系统内各光学元件在激光辐照下的热力学过程,计算结果能直接反映激光器包括功率和光束质量等最为重要的性能指标,是实现高能激光关键问题辨析和优化设计的重要工具。     

Recent advances in polymer reaction engineering: Modeling and control of polymer properties

Complex reaction kinetics and mechanisms, physical changes and transport effects, non-ideal mixing, and strong process nonlinearity characterize polymerization processes. Polymer reaction engineering is a discipline that deals with various problems concerning the fundamental nature of chemical and physical phenomena in polymerization processes. Mathematical modeling is a powerful tool for the development of process understanding and advanced reactor technology in the polymer industry. This review discusses recent developments in modeling techniques for the calculation of polymer properties including molecular weight distribution, copolymer composition distribution, sequence length distribution and long chain branching. The application of process models to the design of model-based reactor optimizations and controls is also discussed with some examples. This paper is dedicated to Professor Hyun-Ku Rhee on the occasion of his retirement from Seoul National University.     

不可压热流体中气体传质扩散过程的数值模拟

控制流体流动中溶解的气体分子浓度能有效控制流动过程中的化学反应,而由热产生的自然对流能够加强气体分子的传递,因此研究气体分子在热流体流动中的扩散混合过程有重要意义。应用格子Boltzmann方法,耦合热效应和扩散效应,数值模拟了一个简化的容器中随着自然对流的发展,溶解的氧气分子在整个容器中的扩散过程。首先建立了二维9速模型的双扩散模型来模拟热量和质量的双扩散对流。为了考察不同自然对流流动对气体分子传递的影响,设计了3种不同给热条件,对不同热流动的形成过程和气体分子扩散过程进行了模拟,与文献结果吻合良好。通过详细分析热边界如何影响流动和传质过程,证实了模拟的速度场与文献数据差异的合理性,同时为控制气体传质过程提供给热条件的设计依据。     

Chemical reaction fouling of organic fluids

Chemical reaction fouling of heat exchangers involves deposition that is caused by chemical reactions which occur in the fluid, or on the surface itself. The factors which influence fouling of organic fluids via autoxidation and thermal decomposition processes are described and the dependence of the rate of thermal fouling on chemical effects and process variables demonstrated. Mitigation techniques are outlined in brief.     

A Statistical Thermodynamic Model of Vapor-Liquid Interfacial Tension for Liquid Mixtures at High Pressure

1 INTRODUCTIONInterfacial tension of pure fluids and their mixtures is an important property for the development,design and simulation of many chemical processes.The interfacial behavior has important prac-tical applications in material science,environment science and chemical engineering separationprocesses as well as in secondary or tertiary recovery of petroleum.Although interfacial phenom-ena are rather complicated,interfacial tension of free vapor-liquid interface is considered as a firstand fundamental step of the study.For example,enhanced carbon dioxide“flooding”technique     

Entwicklungsstand und Perspektiven der Modellierung von Transportvorgängen in durchströmten Festbetten

New model equations enable the consistent and accurate calculation of heat transport, mass transport and chemical reactions in packed beds with fluid flow. The main features of this approach are reviewed and summarized, and selected aspects are discussed. The modelling approach may be a good starting point for the development of, for instance, membrane reactors and separation processes such as chromatography or freeze drying for thermally sensitive products.     

Mathematical reactor modelling for coupled chemical and electrochemical processes: the ECE system

A procedure for modelling electrochemical reactions and reactors which involve heterogeneous reaction, homogeneous fast chemical reaction and diffusional mass transport is described. The procedure can be applied to any combination of first order reaction processes utilising numerical routines for the solution of initial value differential equations. By the use of collocation it can be extended to higher order processes. The reactor types considered are batch, plug flow and dynamic continuous stirred tanks and reactors with recycle. Operation with either potentiostatic, galvanostatic or constant cell voltage control is described and illustrated using the ECE reaction mechanism, involving successive electrochemical, chemical and electrochemical reaction.     

绿色产业超临界技术最新研究进展-在化学反应工程中的应用

超临界流体技术具有许多传统技术所没有的快速、高效、低能耗、污染少等优点，而且超临界流体无毒，不燃，不污染环境，可以设计实现许多新型、高效的绿色化工过程。介绍了超临界流体的密度、粘度、扩散系数等物理化学性质及其对化学反应的影响。重点论述了超临界水的性质、超临界流体在化学反应工程研究中的应用和由超临界流体实现的绿色化工过程。     

Probing the cybotactic region in gas-expanded liquids (GXLs)

Gas-expanded liquids (GXLs) are a new and benign class of liquid solvents, which may offer many advantages for separations, reactions, and advanced materials. GXLs are intermediate in properties between normal liquids and supercritical fluids, both in solvating power and in transport properties. Other advantages include benign nature, low operating pressures, and highly tunable properties by simple pressure variations. The chemical community has only just begun to exploit the advantages of these GXLs for industrial applications. This Account focuses on the synergism of experimental techniques with theoretical modeling resulting in a powerful combination for exploring chemical structure and transport in the cybotactic region of GXLs (at the nanometer lengthscale).     

Separation processes

A review is given of the historical background to the importance of separation processes in chemical engineering. Whereas distillation remains the most important process for large scale separation of miscible fluids, recent developments, particularly in the area of biochemical engineering, have given a stimulus to the development of some highly discriminating techniques, including membrane technology, selective adsorption, liquid extraction using special solvents, and affinity methods.     

基于遗传算法和有限元方法的

以遗传算法作为工艺条件的优化方法，以化学反应过程的有限元模拟方法作为目标函数的求解方法，可以建立化学工艺的优化系统。以硅橡胶材料的硫化反应为例，建立了面向设定值的反应效率优化模型，确定了相关的决策变量，叙述了优化问题的求解步骤。最后通过典型算例展示了工艺条件的优化过程。     

Modeling the Electrokinetic Decontamination of Concrete

Abstract

The decontamination of concrete is a major concern in many Department of Energy (DOE) facilities. Numerous techniques (abrasive methods, manual methods, ultrasonics, concrete surface layer removal, chemical extraction methods, etc.) have been used to remove radioactive contamination from the surface of concrete. Recently, processes that are based on electrokinetic phenomena have been developed to decontaminate concrete. Electrokinetic decontamination has been shown to remove from 70 to over 90% of the surface radioactivity. To evaluate and improve the electrokinetic processes, a model has been developed to simulate the transport of ionic radionuclei constituents through the pores of concrete and into the anolyte and catholyte. The model takes into account the adsorption and desorption kinetics of the radionuclei from the pore walls, and ion transport by electro-osmosis, electromigration, and diffusion. A numerical technique, orthogonal collocation, is used to simultaneously solve the governing convective diffusion equations for a porous concrete slab and the current density equation.

This paper presents the theoretical framework of the model and the results from the computation of the dynamics of ion transport during electrokinetic treatment of concrete. The simulation results are in good agreement with experimental data.

     

锂离子电池介尺度电化学反应非均匀性

锂离子电池是重要的一类能量存储与转化装置。本文从化工角度上出发,将电池视为一类“特殊的”化工反应器,其中也存在着“三传一反”：电子传输、离子传输、热量传递和电化学反应。电极是这些传递与反应过程发生的主要场所;在不同空间与时间尺度上,电极中的传递与反应过程具有不均匀性,进而导致电池材料的利用与失效的差异。本文进一步讨论了研究电极反应不均匀性的必要性,并从准二维电极模拟计算与多尺度表征分析技术两个角度,对不均匀电极反应过程的传质、传热过程、电化学反应过程、电极结构演变规律、电极失效机制等方面的研究进行综述,对未来高性能、长寿命和具备快充性能的电池开发具有一定的指导意义。     

R. Byron Bird: The integration of transport phenomena into chemical engineering

This article, as is this issue of the AIChE Journal, is a tribute to R. Byron Bird, who has had a profound impact on the discipline of chemical engineering, playing a dominant role in the chemical engineering science paradigm shift that occurred around 1960. His textbook, Transport Phenomena, with Warren Stewart and Edwin Lightfoot, fundamentally changed the way chemical engineers are taught fluid mechanics, heat transfer, and mass transfer. By showing the interconnections among molecular, microscopic, and macroscopic treatments of these three transport processes, as well as the underlying similarities among the three transport processes, he has enabled chemical engineers to contribute to many new areas. In his research he has focused on polymeric fluids – their rheology and fluid mechanics – again spanning molecular to macroscopic problems. Bird is also known throughout the profession as a superb teacher and lecturer. He is gifted in languages and music, and he has a great love of the outdoors. In this article, I try to highlight some of Bird's history and accomplishments in these many areas. His influence is clear in the papers that follow. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1219–1224, 2014