The Neal Amundson era. Rapid evolution of chemical engineering science

Neal Amundson (1916–2011) influenced the chemical engineering profession more profoundly than any other single individual, and in this article the author has attempted to capture the man and his era, as well as his lasting legacy. His influence extended well beyond those of other chemical engineers of renown, whether they were known for exploring and establishing new avenues, or for the resolution of outstanding issues, or for other forms of creative endeavors. Amundson reached into the depths of the profession, noted for its expanse, complexity and diversity that had led earlier efforts into a shrine of empiricism, to foster a culture of strongly scientific thinking with a mathematical edifice, which must be the crux of all engineering. The growth of chemical engineering science owes most significantly to Amundson's extraordinary role as an educator, department head and leader, and to the lasting impact of his contributions to chemical engineering research and practice. This article is in salutation of the man who came to be known as the Minnesota Chief, and was responsible for an academic movement that raised the intellectual level of the chemical engineering profession. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3147–3157, 2013     

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.     

A novel fluorinated polymeric product for photoreversibly switchable hydrophobic surface

A new chemical product, that is, photoreversibly switchable hydrophobic surface coating, was synthesized by atom transfer radical polymerization and graft‐from method based on molecular design. Focusing on the strategy of new product development from the chemical product engineering perspective, the product characterization, switching mechanism analysis, performance evaluation, and model interpretation were carried out to confirm the new product manufacture and to ensure the product application with a following aging test. The results show that the product enables surfaces to have reversibly switchable wettability and excellent stability after a month‐long test with eight irradiation cycles. Additionally, the wetting behavior of silicon surface can be tuned between hydrophilicity and hydrophobicity based on blank sample using the surface engineering technique (decorated with functional film and surface roughening). The product presented here can be utilized for constructing a hydrophobic surface with photo‐induced controllable wettability in moisture‐resistance, and it also offers a new technique for the manipulation of liquids in microfluidic devices. © 2014 American Institute of Chemical Engineers AIChE J 60: 4211–4221, 2014     

Generalized model of heat transfer and volatiles evolution inside particles for coal devolatilization

Devolatilization is acknowledged as the first important step in coal conversion techniques. A comprehensive heat transfer and devolatilization model was established, with special consideration of the particle‐scale physics and chemistry, to predict the internal heat transport and pyrolysis behavior of particles. The chemical percolation devolatilization model with corrected kinetic parameters and structure parameters was validated with a lot of experimental data and then adopted to describe the devolatilization behaviors under a broader range of temperatures, heating rates, and coal types. The newly achieved understanding of the integrated effect of heating rate and coal type on coal devolatilization could help to provide a preliminary coal rank selection method for industrial processes. In particular, in‐depth discussion of the influences of heat conduction, volatiles diffusion, and endothermic heat of devolatilization inside particle indicated the dominant roles of these factors when the intensity of heat transfer was strong or the release of volatiles was rapid. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2893–2906, 2014     

化工装置反应能量系统的(火用)传递描述

对反应(能量)系统的描述,焓分析法单讲能的量的利用,火用分析法只作静态描述,只有火用传递法可作动态描述。运用火用传递理论分析,反应系统具有化学火用转换元在系统中起主导作用,各输火用元皆以反应高温火用源为公共火用源,呈放射型并联结构的特点。据此建立的反应系统通用火用传递模型——化学火用转换元与输火用元并联群相串联的串-并联复合结构模型,清楚地显示了模型的结构特点和基本特征。基于反应系统化学平衡、火用平衡方程和传递学原理建立的系统火用传递方程,揭示了系统中计量和过量反应物、生成物,以及杂质等各项火用流变化率的性质及其相互转换或传递的数量关系,由此可获得对反应系统火用传递机理的清晰描述,进而可以作反应系统的火用传递计算和火用传递分析。     

Contact dynamic modeling of a liquid droplet between two approaching porous materials

A computational fluid dynamics model based on a finite difference solution to mass and momentum conservation equations (Navier–Stokes equations) for a liquid droplet transport between two porous or nonporous contacting surfaces (CSs) is developed. The CS dynamic (equation of motion) and the spread of the incompressible liquid available on the primary surface for transfer are coupled with the Navier–Stokes equations. The topologies of the spread dynamic between and inside both surfaces (primary and CSs) are compared with experimental data. The amount of mass being transferred into the CS, predicted by the model, is also compared to the experimental measurements. The impact of the initial velocity on the spread topology and mass transfer into the pores is addressed. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2346–2353, 2014     

Electro-membrane reactor: A powerful tool for green chemical engineering

Electro-membrane reactors use electro-membranes for preferentially diffusive/electrophoretic migration or electroosmotic separation of in-situ reactive products, thereby maximizing the reaction rate and transport efficiencies of the products. These reactors are widely employed in the chemical engineering sectors such as green chemical synthesis, biorefining, electrocatalytic reduction/oxidation, and water treatment. In this review article, we provide an overview of the recent advances in three categories of electro-membrane reactors in chemical engineering sectors from three categories: (1) Electro-membrane reactors based on stacked ion-exchange membranes for resources recovery; (2) Electro-membrane reactors via Faraday reactions on functional anodes/cathodes for substance transformation; and (3) Closed-loop chemical reactions and substance separation via coupling of Faraday reactions and stacked membranes. The increasing demand for low-carbon economy has accelerated the advancement of environmentally friendly chemical engineering and sustainable processes and necessitates the use of electro-membrane processes. The macro perspective provides a timely reference for researchers and engineers.     

On the quantification of the controlling regimes in automotive catalytic converters

The conversion of pollutants in automotive catalytic converters is influenced by a number of physical and chemical processes that take place in the gaseous and solid phases as the exhaust gases flow through the converter. A detailed understanding of the complex processes involving flow dynamics, heat and mass transport and heterogeneous surface reactions is of crucial importance to improve the converter design. The main objective of the present study is to quantify the magnitudes of the external and internal mass transfer as well as chemical reaction limiting processes as a function of the converter operating temperature. To this end, experimental data, obtained for a three way catalyst (TWC) under real world operating conditions, are analyzed and compared against analytical expressions that allow for the quantification of the different limiting processes involved. The results demonstrate that (i) the external mass transfer resistance overlaps the reaction resistance only at moderate operating temperatures and not immediately above the ignition temperature as generally considered in the literature, (ii) the transport phenomena (external and internal mass transfer) represents 90% of the total resistance for temperatures higher than 792 K, (iii) the internal mass transfer in the porous washcoat presents a larger resistance than the external mass transfer from the bulk fluid to the washcoat wall even at high operating temperatures, and (iv) based on the quantification of the individual resistances as a function of the TWC operating temperature, it was demonstrated both the influence of the substrate cell density and of the effective diffusivity on the TWC conversions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Forced convection mass deposition and heat transfer onto a cylinder sheathed by protective garments

In chemical, biological, radiological, and nuclear protective clothing, a layer of activated carbon material in between two textile layers provides protection against hazardous gases. A cylinder in cross flow, sheathed by such material, is generally used to experimentally test the garment properties. This is, however, complicated and predictive models are needed. We present a computational fluid dynamics model for the initial phase in which the carbon filter material is not yet saturated. The textiles are modeled as chemically inactive porous layers, the carbon filter particles have been resolved explicitly. The model has been validated against experimental data. We demonstrate that (1) computational fluid dynamics simulations can be used for the efficient design and optimization of protective garments, and (2) the addition of a highly porous active carbon layer highly increases the chemical protection capabilities, while having relatively little negative impact on the thermal comfort of protective garments. © 2013 American Institute of Chemical Engineers AIChE J, 60: 353–361, 2014     

化学非均一表面及其在化工中的应用

目前流体在纳微尺度下的化学非均一表面上表现出的优异性能已引起普遍关注,但是如何使其在化工中得以应用成为化学工程师们面临的难题之一。本文在分析了化学非均一表面在化工应用中已表现出优异性能的基础上,从化学非均一表面的润湿行为和受限空间下化学非均一对分子传递的影响两方面综述了其研究进展。认为化学非均一表面的表面性质受到诸多因素影响非常复杂,但利用现代表面技术和分子模拟的手段,可从微观、分子层面研究流体在化学非均一表面的作用机理,进而可改善和提高诸多化工过程,是推动现代化工发展的重要途径之一。     

A multiscale,biophysical model of flow‐induced red blood cell damage

A new model for mechanically induced red blood cell damage is presented. Incorporating biophysical insight at multiple length scales, the model couples flow‐induced deformation of the cell membrane (～10 µm) to membrane permeabilization and hemoglobin transport (～100 nm). We estimate hemolysis in macroscopic (above ～1 mm) 2‐D inhomogeneous blood flow by computational fluid dynamics (CFD) and compare results with literature models. Simulations predict the effects of local flow field on RBC damage, due to the combined contribution of membrane permeabilization and hemoglobin transport. The multiscale approach developed here lays a foundation for a predictive tool for the optimization of hydrodynamic and hematologic design of cardiovascular prostheses and blood purification devices. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1509–1516, 2014     

Dynamics of droplets and mass transfer in a rotating packed bed

To do further research on the mass‐transfer mechanism in rotating packed bed (RPB), dynamics of droplets in a RPB are studied by an analytical approach combined with a series of laboratory measurements. Based on the results of the fluid dynamics, mathematical models of mass‐transfer coefficient and mass‐transfer process in RPB are proposed, respectively. Mass‐transfer experiments in RPB are also carried out using ethanol–water solution. By comparison, the results of simulation agree well with that of the experiment, which demonstrate that both hydrodynamic model and mass‐transfer models can better describe the real conditions of RPB. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2705–2723, 2014     

A tribute to professor Roger Sargent: Intellectual leader of process systems engineering

This article and this issue of the AIChE Journal, is a tribute to Professor Roger Sargent who, as pioneer and intellectual leader of process systems engineering, has had a profound impact on the discipline of chemical engineering. Spanning more than five decades, his work has provided a strong mathematical foundation to process systems engineering through the development of sophisticated mathematical and computational tools for the simulation, design, control, operation and optimization of chemical processes. In this article we first give a brief overview of his career that included several leadership positions and the establishment of the Centre for Process Systems Engineering (CPSE) at Imperial College London. We next review his research contributions in the areas of process modeling, differential algebraic systems, process dynamics and control, nonlinear optimization and optimal control, design under uncertainty, and process scheduling. We highlight the tremendous impact that he has had through his students, students' students, and his entire academic family tree, which at present contains over 2000 names, probably one of the largest among the academic leaders of chemical engineering. Finally, we provide a brief overview of him as a modest and charming individual with a wonderful sense of humor. He is without doubt a true intellectual giant who has helped to expand the scope of chemical engineering by providing a strong systems component to it, and by establishing strong multidisciplinary links with other fields. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2951–2958, 2016     

化学产品工程再认识

化学产品工程作为化学工程学科的一个新方向或化学工程学科的新范式已提出很多年,但学术界对其学科内涵理解不一。本文对化学产品工程的学科内涵进行了分析和探讨,认为其核心是通过过程和设备对产品的纳微结构和复杂大分子结构进行调控;化学产品工程仍隶属过程工程,是面向高附加值产品、实现产品结构可控、定向、高效制备的过程工程。通过与传统的以满足市场需求和提高生产效率为目标的过程开发和放大的化学工程研究类比,提出了化学产品工程的主要研究内容,并讨论了其研究的方法论问题,以推动相关的基础研究工作。     

Hydrodynamic interactions between two slender tori in a viscous fluid

As a gift to Professor Bird, hydrodynamic interactions between two slender toroidal particles immersed in a viscous fluid are derived to extend the Rotne–Prager–Yamakawa (RPY) tensor formulation of bead‐spring and bead‐rod models of polymer kinetic theory to toroidal beads. As a relatively simple example of a multiply connected domain, this model geometry exhibits the special “role of the hole” and features new tensorial constructs beyond the Oseen–Burgers and Stokes quadrupoles that are encountered in the classical RPY theory. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1517–1522, 2014     

Predictions of porosity and fluid distribution through nonspherical‐packed columns

For beds comprised randomly arranged nonspherical particles, the prediction and understanding of the packing characteristics and subsequent fluid flow through the resulting porous media is a longstanding problem for chemical and process engineers. This paper presents the application of a digital modeling approach to particle packing, in which no more than elementary physical concepts are used, with the model using collision points to predict trends in bed structures of particles of different geometry. Lattice Boltzmann modeling (LBM), coupled to the output of the packing model, is used to subsequently assess velocity distribution through the generated structures. Simulation results are compared with data available from the literature, as a means of model validation, where it is demonstrated that the combined approach of the digital packing algorithm and LBM provide a modeling capability that is of value to a range of engineering applications. © 2011 American Institute of Chemical Engineers AIChE J, 2012     

旋转床超重力环境下多相流传递过程研究进展

旋转填充床作为一种高效的传质、分离与反应设备,在化工、环境保护、纳米材料制备、能源、制药等工业过程得到广泛应用。本文对旋转填充床超重力环境下,流体力学特性、传质性能、微观混合、多尺度传递特性等方面的研究进行了总结归纳。近年来,随着计算机科学与多相流传递过程的研究进展,对传递过程的研究也由实验手段为主转变为实验与数值模拟相结合的手段,对有关的数值模拟研究以及相应的多相流模型也予以总结描述。在此基础上,对旋转填充床超重力环境下多相流研究的未来发展提出了有关设想。     

Computational chemical engineering–Towards thorough understanding and precise application

The paradigms of chemical engineering discipline are discussed. The first paradigm of Unit Operations and the second paradigm of Transport Phenomena are well recognized among the chemical engineers all over the world, and what the next paradigm is remains still an open question. Several proposals such as Chemical product engineering, Sustainable chemical engineering and Multi-scale methodology are considered as candidates for next paradigm. Might Computational Chemical Engineering be the next one, which is advancing the discipline of chemical engineering toward ultimate mechanism-based understanding of chemical processes? This possibility is comparatively expounded with other proposals, and the scope and depth of computational chemical engineering are shortly listed.