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    - CHEMICAL ENGINEERING (159 journals)
    - CIVIL ENGINEERING (153 journals)
    - ELECTRICAL ENGINEERING (86 journals)
    - ENGINEERING (1135 journals)
    - HYDRAULIC ENGINEERING (48 journals)
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    - MECHANICAL ENGINEERING (76 journals)

ENGINEERING (1135 journals)            First | 1 2 3 4 5 6 7 8 | Last

Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Engineering     Hybrid Journal   (Followers: 9)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 12)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 4)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 15)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 4)
Biomedical Microdevices     Hybrid Journal   (Followers: 7)
Biomedical Science and Engineering     Open Access  
Biomedizinische Technik - Biomedical Engineering     Full-text available via subscription  
Biomicrofluidics     Open Access   (Followers: 2)
BioNanoMaterials     Full-text available via subscription   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 20)
Boletin Cientifico Tecnico INIMET     Open Access  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access  
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 1)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 13)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Case Studies in Thermal Engineering     Open Access   (Followers: 1)
Catalysis Communications     Hybrid Journal   (Followers: 4)
Catalysis Letters     Hybrid Journal   (Followers: 1)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 5)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysis Today     Hybrid Journal   (Followers: 6)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 2)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 2)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 1)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 1)
Chinese Journal of Engineering     Open Access  
Chinese Science Bulletin     Open Access  
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access  
Ciencias Holguin     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 8)
City, Culture and Society     Hybrid Journal   (Followers: 18)
Clay Minerals     Full-text available via subscription   (Followers: 5)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Clinical Science     Full-text available via subscription   (Followers: 4)
Coal Science and Technology     Full-text available via subscription   (Followers: 2)
Coastal Engineering     Hybrid Journal   (Followers: 7)
Coastal Engineering Journal     Hybrid Journal   (Followers: 1)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access  
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 5)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 10)
Communications Engineer     Hybrid Journal  
Communications in Information Science and Management Engineering     Open Access   (Followers: 7)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 3)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 11)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Composite Structures     Hybrid Journal   (Followers: 70)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 50)
Composites Part B : Engineering     Hybrid Journal   (Followers: 68)
Composites Science and Technology     Hybrid Journal   (Followers: 52)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 11)
Computational Optimization and Applications     Hybrid Journal   (Followers: 5)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 8)
Computers & Geosciences     Hybrid Journal   (Followers: 6)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 4)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 5)
Computing and Visualization in Science     Hybrid Journal   (Followers: 3)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 11)
Conciencia Tecnologica     Open Access   (Followers: 1)
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Conference Proceedings - Lucian Blaga University Sibiu     Open Access  
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 4)
Control Engineering Practice     Hybrid Journal   (Followers: 16)
Control Theory and Informatics     Open Access   (Followers: 4)
Corrosion Science     Hybrid Journal   (Followers: 19)
Corrosion Series     Full-text available via subscription   (Followers: 5)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 2)
Design Journal     Full-text available via subscription   (Followers: 15)
Designed Monomers and Polymers     Hybrid Journal   (Followers: 2)
Designs, Codes and Cryptography     Hybrid Journal   (Followers: 5)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover AIChE Journal
   [21 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0001-1541 - ISSN (Online) 1547-5905
     Published by John Wiley and Sons Homepage  [1604 journals]   [SJR: 0.889]   [H-I: 94]
  • Particle‐scale modeling of coal devolatilization behaviors for coal
           pyrolysis in thermal plasma reactors
    • Authors: Binhang Yan; Yan Cheng, Yi Cheng
      Pages: n/a - n/a
      Abstract: A generalized heat transfer and devolatilization model coupled with the thermal balance between the heating gas and particles was established to predict the complex coal pyrolysis behaviors in the practical plasma reactors. It was proved that this model could well describe the coal devolatilization behaviors in both the pilot‐scale and lab‐scale plasma reactors since the mechanisms of coal chemistry and particle‐scale physics were incorporated. The achieved understanding on the reactor energy balance demonstrated that the heat recovery of the quenching process was crucial to the thermal efficiency and economic benefit of the overall project. The in‐depth discussion of the influences of coal feed rate and particle size on the reactor performance revealed the dominant roles and presented the optimal values of these two factors. In particular, the simulation results of several coals could help to provide a simple, quick method of coal type selection for industrial plasma processes. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-25T10:59:00.653138-05:
      DOI: 10.1002/aic.14698
  • Transport processes at single droplets in micellar liquid/liquid systems
    • Authors: Niklas Paul; Sebastian Schön, Regine von Klitzing, Matthias Kraume
      Pages: n/a - n/a
      Abstract: In many industrial applications the knowledge of the occurring transport processes in liquid/liquid systems is of great interest to design a multiphase reactor or an extraction column, for instance. All transport processes in liquid/liquid systems are governed by the interface. In some processes surfactants are needed. Surfactants change many interfacial properties which affect the transport processes. In this work the influence of high surfactant concentrations (micellar systems) on transport processes is regarded. To understand the occurring reduction of the drop rise velocity and of mass transfer rates experimental investigations of the occurring interfacial phenomena are carried out. Therefore, interfacial tension measurements as well as colloidal probe atomic force measurements of liquid/liquid systems were conducted. It was proved that for high nonionic surfactant concentrations a change of the phase behavior must be taken into consideration to describe transport processes in micellar liquid/liquid systems. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-25T10:56:04.830817-05:
      DOI: 10.1002/aic.14699
  • A new mechanistic model to predict gas‐liquid interface shape of
           gas‐liquid flow through pipes with low liquid loading
    • Authors: A. Banafi; M.R. Talaei
      Pages: n/a - n/a
      Abstract: The present paper is concerned with devising a new mechanistic method to predict gas‐liquid interface shape in horizontal pipes. An experiment was conducted to find the pressure gradients of air‐water flow through a 1 inch pipe diameter. Comparing results of model with some experimental data available in the literature demonstrates that the model provides quite better predictions than existed models do. This model also predicts flow regime transition from stratified to annular flow better than ARS (Apparent Rough Surface) and MARS (Modified Apparent Rough Surface) models for both 1 and 2 inch pipe diameters. The model also leads to reliable predictions of wetted wall fraction experimental data. Although one parameter of new model was evaluated based on air‐water flow pressure loss experimental data for 1 inch pipe, it was considerably successful to predict pressure drop, liquid holdup, stratified‐annular transition and wetted wall fraction for other gas‐liquid systems and pipe diameters. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-20T00:09:43.93212-05:0
      DOI: 10.1002/aic.14696
  • Perspective: 2013 AIChE R. H. Wilhelm award in chemical reaction
           engineering chemical looping technology platform
    • Authors: Liang‐Shih Fan; Liang Zeng, Siwei Luo
      Pages: n/a - n/a
      PubDate: 2014-11-19T09:34:01.795324-05:
      DOI: 10.1002/aic.14695
  • A novel approach to determine wet restitution coefficients through a
           unified correlation and energy analysis
    • Authors: Vinayak S. Sutkar; Niels G. Deen, Johan T. Padding, Vitalij Salikov, Britta Crüger, Sergiy Antonyuk, Stefan Heinrich, J.A.M. Kuipers
      Pages: n/a - n/a
      Abstract: Wet particle interactions are observed in many applications e.g. pharmaceutical, food, agricultural, polymerization, agglomeration and coating, in which an accurate evaluation of the wet restitution coefficient (ewet) is crucial to understand the particle flowability, operating conditions and product size distribution. In this work, experiments were performed to measure the wet restitution coefficient by impacting a spherical particle on a stationary plate covered with a thin liquid layer of water or glycerol solution. Furthermore, novel approaches for estimation of ewet were developed using dimensional analysis (using the Buckingham π theorem and regression analysis) in combination with energy budget analysis. In the correlation development, the dominant physical properties of solid and liquid, particle impact velocity and liquid layer thickness are grouped into well‐known dimensionless numbers viz. Reynolds, Weber and Stokes. Whereas in the energy analysis, the energy dissipation rates were determined for five distinct collision phases i.e. dipping, dry collision, un‐dipping, formation and breakage of the liquid bridge, and added mass. The efficacy of the developed approaches was analysed by comparing obtained results with experiments and an elastohydrodynamic model, and a modified elastohydrodynamic model. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T22:35:07.223628-05:
      DOI: 10.1002/aic.14693
  • PEPT study of particle cycle and residence time distributions in a Wurster
           fluid bed
    • Authors: Liang Li; Anders Rasmuson, Andy Ingram, Mats Johansson, Johan Remmelgas, Christian von Corswant, Staffan Folestad
      Pages: n/a - n/a
      Abstract: Particle cycle and residence time distributions are critical factors in determining the coating quality in the Wurster process. In this work, PEPT experiments are performed to determine the cycle and residence times of particles in different regions of a Wurster fluid bed. The results show that particles tend to recirculate in and sneak out below from the Wurster tube. The experiments also show that a larger batch size leads to a shorter cycle time and a narrower cycle time distribution. It is possible to avoid recirculations and obtain a shorter cycle time and a narrower cycle time distribution by selecting the operating conditions appropriately or via equipment design. Experiments using binary mixtures of particles with a diameter ratio of 1.5 show that large particles have a longer cycle time than small particles and that the cycle time is shorter for mixtures with approximately equal amounts of small and large particles. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T10:33:42.763449-05:
      DOI: 10.1002/aic.14692
  • Blend uniformity and powder phenomena inside the continuous tumble mixer
           using DEM simulations
    • Authors: Miguel Florian‐Algarin; Rafael Méndez
      Pages: n/a - n/a
      Abstract: Powder mixing is an essential operation in pharmaceutical, food, and petrochemical industries. Pharmaceutical companies have been working in the implementation of continuous processes as an alternative to the batch process using the Food and Drug Administration (FDA) Process Analytical Technology (PAT) initiative. The main goal of this study was to understand the mixing phenomena inside the continuous tumble mixer and monitor blend uniformity using Discrete Element Method (DEM). Results demonstrated that the main mixing mechanism is convection similar to the common tumbling mixers. This mechanism is driven by the bulk flow of the particles, due to the mixer rotation. The simulations' results, demonstrated that the cohesion reduces the concentration variability due to the higher hold‐up, particle interactions and mean residence time. The blend uniformity at the exit of the system was measured and a relationship between relative standard distribution (RSD), cohesion, and the collision frequency was found. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T10:33:26.89043-05:0
      DOI: 10.1002/aic.14694
  • Dimensional analysis of a novel low pressure device for the production of
           size‐tunable nanoemulsions
    • Authors: I. Souilem; C.A. Serra, R. Muller, Y. Holl, M. Bouquey
      Pages: n/a - n/a
      Abstract: A novel low pressure device was used to generate nanoemulsions of methyl methacrylate. This device is based on a strong elongational flow known to be more efficient than the shear flow for dispersive mixing. The influence of process parameters (pressure drop number of cycles, number and size of holes) and composition parameters (monomer fraction, surfactant concentration,…) on droplet size has shown that the average droplet size can be tailored in the range 30 – 200 nm by adjusting these parameters. The objective of the present paper is to find correlations that relate the obtained droplet size to the studied process and composition parameters. This model is based on a dimensional analysis using the Buckingham theorem in order to determine appropriate dimensionless numbers. This approach represents a first step for scaling up the device besides giving a set of parameters allowing to achieve a given droplet size. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:38:39.758988-05:
      DOI: 10.1002/aic.14690
  • The effect of gas diffusion layer compression on gas bypass and water slug
           motion in parallel gas flow channels
    • Authors: D.H. Ye; E. Gauthier, M. J. Cheah, J. Benziger, M. Pan
      Pages: n/a - n/a
      Abstract: Water slugs form in the gas flow channels of Polymer Electrolyte Membrane Fuel Cells (PEMFCs) which hinder reactant transport to the catalyst layer. We report a study correlating video images of slug formation and motion with pressure/flow measurements in parallel gas flow channels. Slugs move when the differential gas pressure exceeds the force to advance the contact lines of the slug with the channel walls. Water slugs can divert the gas flow through the GDL beneath the ribs to adjacent channels. The flow diversion can cause slugs to stop moving. Slug size and motion has been correlated with in‐situ GDL permeabilities as functions of GDL compression. Compression reduces the GDL permeability under the ribs much more than the GDL permeability under the channel. A model is presented to describe the spatio‐temporal location of slugs in a PEMFC flow field. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:38:24.343009-05:
      DOI: 10.1002/aic.14686
  • A fundamental model for valve tray vapor cross‐flow channeling
    • Authors: Jun Wang; Yixin Leng, Hui Shao, Weimin Li, Bin Xue, Chunxiang Huang, Ping Yang, Qian Tan, Tianxing Chen
      Pages: n/a - n/a
      Abstract: An accurate prediction of tray hydraulics is very important for large diameter trays design, and vapor cross‐flow channeling is one of the key points that affect the hydraulics calculation. Therefore, in this article, a theoretical analysis was first conducted to reveal that the energy of gas‐liquid on the tray was closely related to its flow state. Then, a model was obtained on the basis of the principle of the lowest energy, which can be used to calculate vapor cross‐flow channeling. The model shows that the ratio of dry tray pressure drop to liquid height on a tray determines the gas distribution on the tray. Finally, the model was tested by comparisons with experimental results available in reference. The agreements are good. Furthermore, the effects of liquid load and fractional hole area on vapor cross‐flow channeling were studied. The results are consistent with the field experience summarized in literatures. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:38:08.64152-05:0
      DOI: 10.1002/aic.14691
  • 1‐Dimensional productivity assessment for on‐field methane
           hydrate production using co2/n2 mixture gas
    • Authors: Dong‐Yeun Koh; Yun‐Ho Ahn, Hyery Kang, Seongmin Park, Joo Yong Lee, Se‐Joon Kim, Jaehyoung Lee, Huen Lee
      Pages: n/a - n/a
      Abstract: The direct recovery of methane from methane hydrate bearing sediments is demonstrated, where a gaseous mixture of (CO2+N2) is used to trigger a replacement reaction in complex phase surroundings. A 1D high‐pressure reactor (8 m) was designed to test the actual aspects of the replacement reaction occurring in natural gas hydrate reservoir conditions. Natural Gas Hydrate (NGH) can be converted into CO2 hydrate by a ‘replacement mechanism,’ which serves double duty as a means of both sustainable energy source extraction and greenhouse gas sequestration. The replacement efficiency controlling totally recovered CH4 amount is inversely proportional to (CO2+N2) injection rate directly affecting contact time. A qualitative analysis on compositional profiles at each port reveals that the length more than 5.6 m is required to show noticeable recovery rate for NGH production. The present outcomes are expected to establish the optimized key process variables for near future field production tests. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:37:43.809754-05:
      DOI: 10.1002/aic.14687
  • Proposal and Verification of a Kinetic Mechanism Model for NOx Removal
           with Hydrazine Hydrate
    • Authors: L. Hong; L. J. Yin, D. Z. Chen, D. Wang
      Pages: n/a - n/a
      Abstract: In this study, a relatively precise kinetic mechanism of NOx reduction using N2H4·H2O in a selective non‐catalytic reduction (SNCR) process was proposed and verified by experiment. The dominant radicals and reactions were confirmed, and the proper ranges of key parameters were determined through sensitivity analysis. Both experiment and simulation results show that the effective temperatures exhibit a bimodal distribution with the optimum temperatures being approximately 893K and 1248K and the lower temperature window falling in the range of 848 to 973K. The optimum residence time of the reaction was 0.2~0.35s under the research conditions, and a longer residence time would lead to the re‐generation of NOx. The normalized stoichiometric ratio (NSR) of 3.0 corresponded to the lowest temperature window, and a higher NSR value would make the temperature window shift to a higher temperature range. This kinetic mechanism model for the N2H4·H2Obased De‐NOx process will serve its precise application. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T03:34:12.489072-05:
      DOI: 10.1002/aic.14688
  • Hydrogen and carbon dioxide adsorption with tetra‐n‐butyl
           ammonium semi‐clathrate hydrates for gas separations
    • Authors: Hiroyuki Komatsu; Masaki Ota, Yoshiyuki Sato, Masaru Watanabe, Richard L. Smith
      Pages: n/a - n/a
      Abstract: Gas adsorption rates of H2, CO2 and H2‐CO2 gas mixture (H2/CO2 = 3.4) with tetra‐n‐butyl ammonium salt (bromide, chloride and fluoride) semi‐clathrate hydrate particles were measured at 269 K to assess their properties for gas separation. Equilibrium gas occupancies in the S‐cages of the particles were in order of (high to low) for HS‐I, TS‐I and SCS‐I structures with the maximum fractional occupancy by CO2 being about 40 %. The CO2 diffusion rate depended on the anion size of the salt, which is attributed to distortion of the S‐cage that is close to the molecular size of CO2. Simulations of semi‐clathrate hydrate particles with theory showed that H2/CO2 selectivities could be as high as 36 (3.0 mol% TBAF) and that selectivities for an ideal membrane (3.3 mol% TBAF) could be greater than 100 (269 K, 0.3 – 4.5 MPa). Semi‐clathrate hydrates have wide application as separation media for gas mixtures. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T03:33:09.598354-05:
      DOI: 10.1002/aic.14689
  • A New Process for Fuel Ethanol Dehydration Based on Modeling the Phase
           Equilibria of the Anhydrous MgCl2 + Ethanol + Water System
    • Authors: Lanmu Zeng; Zhibao Li
      Pages: n/a - n/a
      Abstract: The use of ethanol as a fuel for motor engines has attracted significant attention because of its possible environmental and economic advantages over fossil fuel. However, the energy demand for the ethanol dehydration process significantly impacts its production cost. A new and energy efficient process is developed on the basis of salt extractive distillation, which uses recycled MgCl2 granules as a separating agent. Vapor‐liquor‐equilibria (VLE) data for the ternary MgCl2 + ethanol + water system and the three constituent binary systems were measured at 30, 60, 90 and 101.3 kPa. A large enhancement of relative volatility of the ethanol + water system in the presence of MgCl2 is observed throughout the entire ethanol concentration range, which completely broke the azeotrope. The salt effect of MgCl2 is thought to be the result of energetic interactions and the hydration equilibrium reaction of the Mg2+ ion with water molecules. The calculation results by the mixed‐solvent electrolyte (MSE) model embedded in the OLI platform equipped with new model interaction parameters and equilibrium constant (obtained via the regression of experimental VLE data), provided for a satisfactory means of simulating the MgCl2 salt extractive distillation process. Finally, the process was proven feasible at the laboratory‐scale resulting in large granules of recovered MgCl2 and a product of 99.5 wt% ethanol. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T00:51:41.705104-05:
      DOI: 10.1002/aic.14685
  • Robust algorithms for the solution of the ideal adsorbed solution theory
    • Authors: Enzo Mangano; Daniel Friedrich, Stefano Brandani
      Pages: n/a - n/a
      Abstract: The Ideal Adsorbed Solution (IAS) theory has been shown to predict reliably multicomponent adsorption for both gas and liquid systems. There is a lack of understanding of the conditions which guarantee convergence for various algorithms used to solve the IAS theory equations and inconsistencies are present in the reported computational effort required for the different approaches. The original nested loop and the FastIAS technique are revisited. The resulting system of equations is highly nonlinear but both methods are shown to be robust if appropriate choices are made for the starting values of the unknown variables. New initial conditions are proposed and the resulting algorithms are compared in a consistent manner with the main methods available to solve the IAS theory equations. The algorithms are extended for the first time to all non‐type I isotherms. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T00:50:52.275943-05:
      DOI: 10.1002/aic.14684
  • Economic model predictive control of nonlinear process systems using
           empirical models
    • Authors: Anas Alanqar; Matthew Ellis, Panagiotis D. Christofides
      Pages: n/a - n/a
      Abstract: Economic model predictive control (EMPC) is a feedback control technique that attempts to tightly integrate economic optimization and feedback control since it is a predictive control scheme that is formulated with an objective function representing the process economics. As its name implies, EMPC requires the availability of a dynamic model to compute its control actions and such a model may be obtained either through application of first‐principles or through system identification techniques. In industrial practice, it may be difficult in general to obtain an accurate first‐principles model of the process. Motivated by this, in the present work, Lyapunov‐based EMPC (LEMPC) is designed with a linear empirical model that allows for closed‐loop stability guarantees in the context of nonlinear chemical processes. Specifically, when the linear model provides a sufficient degree of accuracy in the region where time‐varying economically optimal operation is considered, conditions for closed‐loop stability under the LEMPC scheme based on the empirical model are derived. The LEMPC scheme is applied to a chemical process example to demonstrate its closed‐loop stability and performance properties as well as significant computational advantages. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:45:52.076998-05:
      DOI: 10.1002/aic.14683
  • A conceptual model for chemical product design
    • Authors: Fernando P Bernardo; Pedro M. Saraiva
      Pages: n/a - n/a
      Abstract: The fundamental principles of chemical product design and associated systematic tools, within a broad domain of chemical products including molecules, formulations and devices, are still under development. In this paper, we propose a simple and fundamental conceptual model that defines the chemical product design problem as the inversion of three central design functions: quality, property and process functions. The classic iterative cycles of product design problems may be envisioned as alternating between inversion and evaluation of these three functions, or in other words alternating between synthesis and analysis of solutions. On top of the proposed basic structure of the overall design problem, we then discuss the formulation of some subproblems as optimization problems and describe some useful solution tools. Three application examples are provided, including a more detailed case of formulation of a pharmaceutical ointment. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:45:37.22391-05:0
      DOI: 10.1002/aic.14681
  • Effect of dielectric packing materials on the decomposition of carbon
           dioxide using DBD microplasma reactor
    • Authors: Xiaofei Duan; Zongyuan Hu, Yanping Li, Baowei Wang
      Pages: n/a - n/a
      Abstract: Carbon dioxide (CO2) decomposition was carried out at a normal atmosphere and room temperature in dielectric barrier discharge (DBD) microplasma reactors to reduce CO2 emissions and convert CO2 into valuable chemical materials. The outlet gases, including CO2, CO, and O2, were analyzed with gas chromatography. The results indicated that the conversions of CO2 in dielectric material‐packed reactors were all higher than that in non‐packed reactors. Particle size, dielectric constant, particle morphology, and acid‐base properties of the dielectric materials (including quartz wool, quartz sand, γ‐Al2O3, MgO, and CaO) all affected the CO2 decomposition process. The conversion of CO2 and energy efficiency achieved the highest values of 41.9 % and 7.1 % in a CaO‐packed reactor for the higher dielectric constant and basicity of CaO. Quartz wool was also an excellent dielectric packing material because its fiber structure provided rigid sharp edges. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:31:50.865139-05:
      DOI: 10.1002/aic.14682
  • n‐Butane Carbonylation to n‐Pentanal Using a Cascade Reaction
           of Dehydrogenation and SILP‐Catalyzed Hydroformylation†
    • Authors: Simon Walter; Marco Haumann, Hanna Hahn, Robert Franke, Peter Wasserscheid
      Pages: n/a - n/a
      Abstract: A novel gas‐phase process has been developed that allows direct two‐step conversion of butane into pentanals with high activity and selectivity. The process consists of alkane dehydrogenation over a heterogeneous Cr/Al2O3 catalyst followed by direct gas‐phase hydroformylation using advanced supported ionic liquid phase (SILP) catalysis. The latter step uses rhodium complexes modified with the diphosphite ligands biphephos (BP) and benzopinacol (BzP) to convert the butane/butene mixture from the dehydrogenation step efficiently into aldehydes. The use of the BP ligand results in improved yields of linear pentanal because SILP systems with this ligand are active for both isomerization and hydroformylation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-12T03:44:45.864729-05:
      DOI: 10.1002/aic.14676
  • A Systematic Methodology for Kinetic Modeling of Chemical Reactions
           applied to n‐Hexane Hydroisomerization
    • Authors: K. Toch; J.W. Thybaut, G.B. Marin
      Pages: n/a - n/a
      Abstract: Kinetic modeling provides chemical engineers with a unique opportunity to better understand reaction kinetics in general and the underlying chemistry in particular. How to systematically approach a modeling assignment in chemical reaction kinetics is typically less clear, especially for novices in the field. The proposed modeling methodology pursues an adequate compromise between statistical significance and physical meaning of the kinetic model and the corresponding parameters and typically results in models of an appropriate complexity. It comprises the following activities: (i) data analysis, aiming at qualitative information on the reaction mechanism and corresponding rate equations, (ii) model regression to quantify this information via optimal parameter values and (iii) validation of the statistical significance and physical meaning of the parameter estimates. This methodology is successfully applied to n‐hexane hydroisomerization on a bifunctional catalyst. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-12T03:20:54.758957-05:
      DOI: 10.1002/aic.14680
  • Composition limits in granulation with active component in the binder
    • Authors: David Smrčka; Marek Schöngut, František Štěpánek, Tomáš Gregor
      Pages: n/a - n/a
      Abstract: The process of reactive granulation is considered. Sodium carbonate primary particles react with dodecyl‐benzenesulfonic acid droplets to form granules where the active component is an anionic surfactant formed by the reaction. The effect of primary particle size on the maximum binder/solids ratio was systematically investigated and found to be directly proportional to the specific surface area of the primary particles regardless of how this surface area was achieved—whether by monodisperse powders or bimodal powder mixtures. The effect of binder viscosity on the maximum binder capacity has shown a nontrivial behavior: while the maximum binder content increased with increasing binder viscosity for fine primary particles, the opposite trend was observed in the case of coarse primary particles. This behavior was explained by detailed studies of primary particle wetting and binder penetration into particle beds, as well as by microtomography analysis of the internal granule structure. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T10:50:16.528965-05:
      DOI: 10.1002/aic.14667
  • When the final catalyst activity profile depends only on the total amount
           of admitted substance: Theoretical proof
    • Authors: Denis Constales; Gregory S. Yablonsky, Phungphai Phanawadee, Nattapong Pongboutr, Jumras Limtrakul, Guy B. Marin
      Pages: n/a - n/a
      Abstract: Significance: it is shown, based on pulse‐response experiments, that under special conditions the activity profile of a prepared catalytic system depends only on the total amount of admitted substance. This property, previously found computationally, is here established mathematically for porous and nonporous catalyst in different pulse reactors This result can be used as a theoretical guidance for the design of systems or materials with optimal activity profile, in particular catalyst bed or catalyst particle. Consequently, it can be used for understanding and developing the different diffusion‐reaction processes: wet impregnation, deactivation of active materials, etc. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T04:54:49.989156-05:
      DOI: 10.1002/aic.14675
  • CO2 removal by single and mixed amines in a hollow‐fiber membrane
           module ‐ Investigation of contactor performance
    • Authors: Ion Iliuta; Francis Bougie, Maria C. Iliuta
      Pages: n/a - n/a
      Abstract: This work investigates CO2 removal by single and blended amines in a hollow‐fiber membrane contactor (HFMC) under gas‐filled and partially liquid‐filled membrane pores conditions via a two‐scale, non‐isothermal, steady‐state model accounting for CO2 diffusion in gas‐filled pores, CO2 and amines diffusion/reaction within liquid‐filled pores and CO2 and amines diffusion/reaction in liquid boundary layer. Model predictions were compared with CO2 absorption data under various experimental conditions. The model was used to analyze the effects of liquid and gas velocity, CO2 partial pressure, single (primary, secondary, tertiary and sterically hindered alkanolamines) and mixed amines solution type, membrane wetting and concurrent/countercurrent flow orientation on the HFMC performance. An insignificant difference between the absorption in cocurrent and countercurrent flow was observed in the present study. The membrane wetting decreases significantly the performance of hollow‐fiber membrane module. The non‐isothermal simulations reveal that the hollow‐fiber membrane module operation can be considered as nearly isothermal. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T03:28:52.156508-05:
      DOI: 10.1002/aic.14678
  • Application of polyethylenimine‐Impregnated solid adsorbents for
           direct capture of low‐concentration CO2
    • Authors: Jitong Wang; Mei Wang, Wencheng Li, Wenming Qiao, Donghui Long, Licheng Ling
      Pages: n/a - n/a
      Abstract: A systematic study of CO2 capture on the amine‐impregnated solid adsorbents is carried out at CO2 concentrations in the range of 400‐5000 ppm, relating to the direct CO2 capture from atmospheric air. The commercially available polymethacrylate‐based HP2MGL and polyethylenimine are screened to be the suitable support and amine respectively for preparation of the adsorbent. The adsorbents exhibit an excellent saturation adsorption capacity of 1.96 mmol/g for 400 ppm CO2 and 2.13 mmol/g for 5000 ppm CO2. Moisture plays a promoting effect on CO2 adsorption but depends on the relative humidity. The presence of O2 would lead to the decrease of adsorption capacity, but do not affect the cyclic performance. The diffusion additive is efficient to improve the adsorption capacity and cyclic performance. Moreover, the adsorbents can be easily regenerated under a mild temperature. This study may have a positive impact on the design of high‐performance adsorbents for CO2 capture from ambient air. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T03:27:12.426087-05:
      DOI: 10.1002/aic.14679
  • Pyrolysis of Heavy Oil in the Presence of Supercritical Water: The
           Reaction Kinetics in Different Phases
    • Authors: Xue‐Cai Tan; Qing‐Kun Liu, Dao‐Qi Zhu, Pei‐Qing Yuan, Zhen‐Min Cheng, Wei‐Kang Yuan
      Pages: n/a - n/a
      Abstract: In the presence of supercritical water (SCW) and N2, the pyrolysis of heavy oil was investigated to distinguish the difference in the reaction kinetics between the upgrading in the SCW and oil phases. The pyrolysis in the SCW phase is faster than that in the oil phase, but the reaction in whichever phase is retarded by vigorous stirring. The pyrolysis can be preferably described by a four‐lump kinetic model consisting of the condensation of maltenes and asphaltenes in series. In the SCW phase, highly dispersed asphaltenes are isolated by water clusters from maltenes dissolved in SCW surroundings, by which the condensation of asphaltenes is drastically accelerated. Benefited from excellent mass transfer environments in SCW, the condensation of maltenes is promoted simultaneously. The introduction of SCW into the pyrolysis of heavy oil results in an effectively increased upgrading efficiency, but its influence on the properties of equilibrium liquid products is minor. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T02:47:42.114472-05:
      DOI: 10.1002/aic.14677
  • Surface tension, adsorption, and wetting behaviors of natural surfactants
           on a PTFE surface
    • Authors: Santanu Paria; Nihar Ranjan Biswal, Rajib Ghosh Chaudhuri
      Pages: n/a - n/a
      Abstract: This study reports the adsorption kinetics and wetting behaviors of three plant‐based natural surfactants (Reetha, Shikakai, and Acacia) on the PTFE surface. Adsorption studies of these surfactants on PTFE surface show the equilibrium adsorption time is ~ 15 min, and Langmuir type isotherm fits well for all three surfactants. The contact angle measurements show that the value achieved by Reetha and Acacia solutions are close (~109°), but that is low in the case of Shikakai (98.13°). While comparing the adsorption densities of the surfactants at PTFE‐water and airwater interfaces, it has been found that adsorption densities at the PTFE‐water interface are low for all three surfactants than that of air‐water interface. The alcoholShikakai mixed solutions show non‐ideal behavior of surface tension reduction through a strong interaction between alcohol and Shikakai molecules, which in turn, show lower surface tension and contact angle values than that of ideal. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-10T03:47:13.015399-05:
      DOI: 10.1002/aic.14674
  • Real‐Time Economic Model Predictive Control of Nonlinear Process
    • Authors: Matthew Ellis; Panagiotis D. Christofides
      Pages: n/a - n/a
      Abstract: Closed‐loop stability of nonlinear systems under real‐time Lyapunov‐based economic model predictive control (LEMPC) with potentially unknown and time‐varying computational delay is considered. To address guaranteed closed‐loop stability (in the sense of boundedness of the closed‐loop state in a compact state‐space set), an implementation strategy is proposed which features a triggered evaluation of the LEMPC optimization problem to compute an input trajectory over a finite‐time prediction horizon in advance. At each sampling period, stability conditions must be satisfied for the precomputed LEMPC control action to be applied to the closed‐loop system. If the stability conditions are not satisfied, a backup explicit stabilizing controller is applied over the sampling period. Closed‐loop stability under the real‐time LEMPC strategy is analyzed and specific stability conditions are derived. The real‐time LEMPC scheme is applied to a chemical process network example to demonstrate closed‐loop stability and closed‐loop economic performance improvement over that achieved for operation at the economically optimal steady‐state. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-10T03:46:28.533226-05:
      DOI: 10.1002/aic.14673
  • Ion‐Exchange Adsorption of Calcium Ions from Water and Geothermal
           Water with Modified Zeolite A
    • Authors: Junchao Song; Mingyan Liu, Yang Zhang
      Pages: n/a - n/a
      Abstract: The modified zeolite A was prepared by a two‐step crystallization method to remove scale‐forming cations from water and geothermal water. The adsorption kinetics, mechanism and thermodynamics were studied. The calcium ion adsorption capacity of the modified zeolite A was 129.3mg/g (1 mg/g=10‐3kg/kg) at 298K. The adsorption rate was fitted well with pseudo second‐order rate model. The adsorption process was controlled by film diffusion at the calcium ion concentration less than 250mg/L (1 mg/L=10‐3 kg/m3), and it was controlled by intraparticle diffusion at the concentration larger than 250mg/L. The calculated mass transfer coefficient ranged from 2.23×10‐5 to 2.80×10‐4cm/s (1 cm/s=10‐2m/s). Dubinin‐Astakhov isotherm model could appropriately describe the adsorption thermodynamic properties when combined with Langmuir model. The adsorption process included not only ion exchange but also complexation between calcium and hydroxyl ions. The adsorption was spontaneous and endothermal in nature. The high adsorption capacity indicates that the modified zeolite A is a good adsorption material for scaling removal from aqueous solution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-07T09:43:32.219097-05:
      DOI: 10.1002/aic.14671
  • Analysis of Solar‐Driven Gasification of Biochar Trickling through
           an Interconnected Porous Structure
    • Authors: Michael Kruesi; Zoran R. Jovanovic, Andreas Haselbacher, Aldo Steinfeld
      Pages: n/a - n/a
      Abstract: The efficient transfer of high‐temperature solar heat to the reaction site is crucial for the yield and selectivity of the solar‐driven gasification of biomass. This work investigates the performance of a gas‐solid trickle‐bed reactor constructed from a high thermal conductivity porous ceramic packing. Beech char particles were used as the model feedstock. A two‐dimensional finite‐volume model coupling chemical reaction with conduction, convection, and radiation of heat within the packing was developed and tested against measured temperatures and gasification rates. The sensitivity of the gasification rate and reactor temperatures to variations of the packing's pore diameter, porosity, thermal conductivity, and particle loading was numerically studied. A numerical comparison with a moving bed projected a more uniform temperature distribution and higher gasification rates due to the increased heat transfer via combined radiation and conduction through the trickle bed. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-07T09:35:45.419313-05:
      DOI: 10.1002/aic.14672
  • Analysis of mass transfer in a corotating disks catalytic reactor
    • Authors: C.T. Gonzalez‐Hidalgo; J. Herrero, D. Puigjaner
      Pages: n/a - n/a
      Abstract: We analyze the flow and mass transfer in a discontinuous reactor configuration consisting of a pair of corotating enclosed disks with a chemical reaction taking place at the disk surfaces. The calculated mass transfer efficiencies do not follow the expected Sh = Sh(Re,Sc) dependence because the overall mass transfer process is not boundary–layer controlled, especially at high Schmidt numbers. It has been found in all of the cases investigated that despite the fact that the reactant concentration is continuously dropping with time its spatial distribution, relative to the volume–averaged value, becomes stationary after a short initial transient. This result implies that the mass transfer efficiency in the discontinuous reactor also becomes stationary and the resulting time–independent value, Sh∞, obtained either directly from calculation or from the fit of the collected results, provides a fairly good estimate of the reactor operation time needed to achieve the target reactant conversion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-07T05:44:10.467164-05:
      DOI: 10.1002/aic.14668
  • Scale‐up of agitated drying: Effect of shear stress and hydrostatic
           pressure on active pharmaceutical ingredient powder properties
    • Authors: Brenda Remy; Weston Kightlinger, Eric Saurer, Nathan Domagalski, Benjamin J. Glasser
      Pages: n/a - n/a
      Abstract: Scale‐up of agitated drying processes to minimize particle size changes in Active Pharmaceutical Ingredients can be challenging. Particle agglomeration or attrition problems due to agitated drying are often discovered upon the initial scale‐up from the lab to the plant. Traditional laboratory drying equipment has not successfully reproduced the degree of agglomeration or attrition observed at scale. This discrepancy may be attributed to the ability of particulate solids, such as crystalline API's, to transfer stresses from the normal direction into the shearing direction. As batch size increases during scale‐up, the compressive and shearing forces experienced by the API increase. To overcome this limitation, a modified laboratory setup was constructed which reproduces the range of hydrostatic pressures observed during scale‐up. This work highlights the use of the modified setup to characterize the propensity for particle attrition to occur at different stages of the drying process by measuring impeller torque. Torque measurements of the API powder at different hydrostatic pressures revealed a behavior consistent with Coulomb's law of friction. The torque data obtained from these measurements was used to determine the bulk friction coefficient for API powder beds at different liquid content. Additionally, the amount of work done by the impeller blades was correlated to the degree of particle attrition observed. A workflow for assessing risk of API attrition at scale is described. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-05T08:17:50.813891-05:
      DOI: 10.1002/aic.14669
  • Catalytic combustion kinetics of isopropanol over novel porous
           microfibrous‐structured ZSM‐5 coating/PSSF catalyst
    • Authors: Huanhao Chen; Ying Yan, Yan Shao, Huiping Zhang
      Pages: n/a - n/a
      Abstract: Porous thin‐sheet cobalt‐copper‐manganese mixed oxides modified microfibrous‐structured ZSM‐5 coating/PSSF catalysts were developed by the papermaking/sintering process, secondary growth process, and incipient wetness impregnating method. Paper‐like sintered stainless steel fibers (PSSF) support with sinter‐locked three‐dimensional networks was built by the papermaking/sintering process, and ZSM‐5 coatings were fabricated on the surface of stainless steel fibers by the secondary growth process. Catalytic combustion performances of isopropanol at different concentrations over the microfibrous‐structured Co‐Cu‐Mn (1:1:1)/ZSM‐5 coating/PSSF catalysts were measured to obtain kinetics data. The catalytic combustion kinetics was investigated by using Power‐rate Law model and Mars‐Van Krevelen model. It was found that the Mars‐Van Krevelen model provided fairly good fits to the kinetic data. The catalytic combustion reaction occurred by interaction between isopropanol molecule and oxygen‐rich centers of modified microfibrous‐structured ZSM‐5 coating/PSSF catalyst. The reaction activation energies for the reduction and oxidation steps are 60.3 kJ/mol and 57.19 kJ/mol, respectively. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-05T08:09:01.132128-05:
      DOI: 10.1002/aic.14670
  • Multiobjective optimization of product and process networks: General
           modeling framework, efficient global optimization algorithm, and case
           studies on bioconversion
    • Authors: Daniel J. Garcia; Fengqi You
      Pages: n/a - n/a
      Abstract: A comprehensive optimization model that can determine the most cost‐effective and environmentally sustainable production pathways in an integrated processing network is needed, especially in the bioconversion space. We develop the most comprehensive bioconversion network to date with 193 technologies and 129 materials/compounds for fuels production. We consider the tradeoff between scaling capital and operating expenditures (CAPEX and OPEX) as well as life cycle environmental impacts. Additionally, we develop a general network‐based modeling framework with non‐convex terms for CAPEX. To globally optimize the nonlinear program with high computational efficiency, we develop a specialized branch‐and‐refine algorithm based on successive piecewise linear approximations. Two case studies are considered. The optimal pathways have profits from ‐$12.9M/yr to $99.2M/yr, and emit 791 ton CO2‐eq/yr to 31,571 ton CO2‐eq/yr. Utilized technologies vary from corn‐based fermentation to pyrolysis. The proposed algorithm reduces computational time by up to three orders of magnitude compared to general‐purpose global optimizers. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-01T11:20:46.375009-05:
      DOI: 10.1002/aic.14666
  • Low‐order optimal regulation of parabolic PDEs with
           time‐dependent domain
    • Authors: Mojtaba Izadi; Stevan Dubljevic
      Pages: n/a - n/a
      Abstract: In this work, observer and optimal boundary control design for the objective of output tracking of a linear distributed parameter system given by a 2D parabolic partial differential equation with time‐varying domain is realized. The transfor‐mation of boundary actuation to distributed control setting allows to represent the system's model in a standard evolutionary form. By exploring dynamical model evolution and generating data, a set of time‐varying empirical eigenfunctions that capture the dominant dynamics of the distributed system is found. This basis is used in Galerkin's method to accurately represent the distributed system as a finite‐dimensional plant in terms of a linear time‐varying system. This reduced‐order model enables synthesis of a linear optimal output tracking controller, as well as design of a state observer. Finally, numerical results are prepared for the opti‐mal output tracking of a 2D model of the temperature distribution in Czochralski crystal growth process which has nontrivial geometry. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-31T04:06:57.774398-05:
      DOI: 10.1002/aic.14664
  • A Two‐Zone Model for Fluid Catalytic Cracking Riser with Multiple
           Feed Injectors
    • Authors: Pengfei He; Chao Zhu, Teh C. Ho
      Pages: n/a - n/a
      Abstract: Developments in modeling of the fluid catalytic cracking (FCC) process have progressed along two lines. One emphasizes composition‐based kinetic models based on molecular characterization of feedstocks and reaction products. The other relies on computational fluid dynamics (CFD). This study aims at developing an FCC model that strikes a balance between the two approaches. Specifically, we present an FCC riser model consisting of an entrance‐zone and a fully‐developed zone. The former has four overlapping, fan‐shaped oil sprays. The model predicts the plant data of Derouin et al. and reveals an inherent two‐zone character of the FCC riser. Inside the entrance zone, cracking intensity is highest and changes rapidly, resulting in a steep rise in oil conversion. Outside the entrance zone, cracking intensity is low and varies slowly, leading to a sluggish increase in conversion. The two‐zone model provides a computationally efficient modeling approach for FCC on‐line control, optimization, and molecular management. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-31T03:50:41.474055-05:
      DOI: 10.1002/aic.14665
  • Operating Condition Diagnosis Based on HMM with Adaptive Transition
           Probabilities in Presence of Missing Observations
    • Authors: Nima Sammaknejad; Biao Huang, Weili Xiong, Alireza Fatehi, Fangwei Xu, Aris Espejo
      Pages: n/a - n/a
      Abstract: In this paper a new approach for modeling and monitoring of the multivariate processes in presence of faulty and missing observations is introduced. It is assumed that operating modes of the process can transit to each other following a Markov chain model. Transition probabilities of the Markov chain are time varying as a function of the scheduling variable. Therefore, the transition probabilities will be able to vary adaptively according to different operating modes. In order to handle the problem of missing observations and unknown operating regimes, the expectation maximization (EM) algorithm is used to estimate the parameters. The proposed method is tested on two simulations and one industrial case studies. The industrial case study is the abnormal operating condition diagnosis in the primary separation vessel of oil‐sand processes. In comparison to the conventional methods, the proposed method shows superior performance in detection of different operating conditions of the process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-27T02:34:58.661927-05:
      DOI: 10.1002/aic.14661
  • Analytical Technology Aided Optimization and Scale‐Up of Impinging
           Jet Mixer for Reactive Crystallization Process
    • Authors: Wen J. Liu; Cai Y. Ma, Jing J. Liu, Yang Zhang, Xue Z. Wang
      Pages: n/a - n/a
      Abstract: Reactive crystallization is widely used in the manufacture of active pharmaceutical ingredients (APIs). Since APIs often have low solubility, traditional stirred tank reactors and the route of process operation and control using metastable zone width are not effective. The current work investigated the integration of an impinging jet mixer and a stirred tank crystallizer that can take advantage of both the reaction and crystallization characteristics, the focus being on design optimization and scale‐up using process analytical techniques based on the Fourier transform Infrared spectroscopy and Focused Beam Reflectance Measurement, as well as X‐ray diffraction and particle imaging Morphologi G3. The parameters for process operation and design of the impinging jet mixer were optimized. The research was carried out with reference to the manufacture of an antibiotic, sodium cefuroxime, firstly in a 1L reactor, then a 10L reactor. The crystals produced showed higher crystallinity, narrower size distribution, higher stability and purity. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-26T23:56:11.697715-05:
      DOI: 10.1002/aic.14662
  • A Bayesian Framework for Real‐time Identification of Locally
           Weighted Partial Least Squares
    • Authors: Ming Ma; Shima Khatibisepehr, Biao Huang
      Pages: n/a - n/a
      Abstract: Just‐in‐time (JIT) learning methods are widely used in dealing with non‐linear and multi‐mode behavior of industrial processes. The locally weighted partial least squares (LW‐PLS) method is among the most commonly used JIT methods. The performance of LW‐PLS model depends on parameters of the similarity function as well as the structure and parameters of the local PLS model. However, the regular LW‐PLS algorithm assumes that the parameters of the similarity function and structure of the local PLS model are known and do not fully utilize available knowledge to estimate the model parameters. In this work, a Bayesian framework is proposed to provide a systematic way for real‐time parameterization of the similarity function, selection of the local PLS model structure, and estimation of the corresponding model parameters. By applying the Bayes' theorem, the proposed framework incorporates the prior knowledge into the identification process and takes into account the different contribution of measurement noises. Furthermore, Bayesian model structure selection can automatically deal with the model complexity problem to avoid the over‐fitting issue. The advantages of this new approach are highlighted through two case studies based on the real‐world near infrared (NIR) data. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-26T23:55:54.459753-05:
      DOI: 10.1002/aic.14663
  • Self‐assembly micelles from novel tri‐armed star
           C3‐(PS‐b‐PNIPAM block copolymers for anticancer drug
    • Authors: Feng Xu; Jing‐Wen Xu, Bi‐Xia Zhang, Yan‐Ling Luo
      Pages: n/a - n/a
      Abstract: Novel tri‐armed star polystyrene‐block‐poly(N‐isopropylacrylamide) block copolymers with trimesic acid as central molecules were synthesized by successive two‐step ATRP, and confirmed by FT‐IR, 1H NMR, and laser light scattering gel chromatography system. The copolymers could self‐assemble into spherical core‐shell micelles in aqueous media independent on drug loading. Physicochemical properties of the blank and drug‐loaded micelles were examined by surface tension, fluorescence spectroscopy, UV‐vis, TEM and DLS measurements. The copolymer micelles exhibited thermo‐triggered phase transition, with low critical solution temperature (LCST) of 33.7 and 34.6 °C, varying with copolymer compositions. The critical aggregate concentrations were 11.62 and 47.61 mg L‐1, and hydrodynamic diameters from 200 to 220 nm. Water‐insoluble 10‐hydroxycamptothecine was encapsulated into the micelle aggregates to investigate the change in the resulting physicochemical parameters, thermo‐triggered in vitro drug release and the applicability as drug targeting release carriers. MTT assays were carried out to uncover cytotoxicity of the newly‐developed micelle‐based drug formulations. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-23T11:18:46.694927-05:
      DOI: 10.1002/aic.14659
  • Reaction pathways in the liquid phase alkylation of biomass‐derived
           phenolic compounds
    • Authors: Miguel Ángel González‐Borja; Daniel E. Resasco
      Pages: n/a - n/a
      Abstract: Alkylation is a promising reaction for the upgrading of bio‐oil because it maximizes the retention of carbon in the liquid product. The alkylation of m‐cresol with isopropanol and HY zeolite was studied in a liquid phase system. The experimental results were fitted with two conventional surface kinetic models, Langmuir‐Hinshelwood and Eley‐Rideal, from which adsorption and rate constants were estimated. Two types of alkylation reactions were observed: C‐alkylation with formation of a C‐C bond with the ring, and O‐alkylation with formation of an ether bond with the hydroxyl group. It was concluded that O‐alkylation products do not undergo intramolecular rearrangement, but first decompose into the corresponding phenolic. Alkylation occurs from both isopropanol and propylene, both of them yielding O‐and C‐alkylation to different extents. Isopropanol favors O‐alkylation while propylene favors C‐alkylation. Rate constants for multiple alkylation steps were progressively lower, suggesting the presence of steric hindrance during incorporation of additional isopropyl groups. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-23T11:18:39.986213-05:
      DOI: 10.1002/aic.14658
  • Hydrodeoxygenation of HMF over Pt/C in a continuous flow reactor
    • Authors: Jing Luo; Lisandra Arroyo‐Ramírez, Raymond J. Gorte, Despina Tzoulaki, Dionisios G. Vlachos
      Pages: n/a - n/a
      Abstract: The three‐phase hydrodeoxygenation (HDO) reaction of 5‐hydroxymethylfurfural (HMF) with H2 was studied over a 10‐wt% Pt/C catalyst using both batch and flow reactors, with ethanol, 1‐propanol, and toluene solvents. The reaction is shown to be sequential, with HMF reacting first to furfuryl ethers and other partially hydrogenated products. These intermediate products then form dimethyl furan (DMF), which in turn reacts further to undesired products. Furfuryl ethers were found to react to DMF much faster than HMF, explaining the higher reactivity of HMF when alcohol solvents were used. With the optimal residence time, it was possible to achieve yields approaching 70% in the flow reactor with the Pt/C catalyst. Much higher selectivities and yields were obtained in the flow reactor than in the batch reactor because side products are formed sequentially, rather than in parallel, demonstrating the importance of choosing the correct type of reactor in catalyst screening. 1 © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-23T11:08:05.664422-05:
      DOI: 10.1002/aic.14660
  • Investigation on liquid flow characteristics in microtubes
    • Authors: Qiao‐Li Chen; Ke‐Jun Wu, Chao‐Hong He
      Pages: n/a - n/a
      Abstract: The fundamental understanding and prediction of liquid flow characteristics in microscale are important to control the performance of microfluidic devices. However, fundamental questions about liquid flow characteristics in microscale have not been settled yet and systematical investigation is needed. A systematical investigation on liquid flow characteristics through microtubes with diameters varying from 44.5‐1011 µm and relative roughness in the range 0.02‐4.32% in the Reynolds number range 29‐11644 was performed in this work, using water as working fluid. Experimental results indicated that early transition occurred when the diameter was smaller than 1000 µm, the transitional flow characteristics for smooth microtubes differed from rough microtubes and the friction factor in turbulent region for rough microtubes was larger than conventional theory. Moreover, a parameter α was proposed to describe the characteristic of microtube. The characteristic parameter was used to calculate the critical Reynolds number and the friction factor in turbulent region for microscale. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-18T05:20:05.122067-05:
      DOI: 10.1002/aic.14656
  • A study on the modelling of static pressure distribution of wet gas in
    • Authors: Peining Yu; Ying Xu, Tao Zhang, Zicheng Zhu, Xili Ba, Jing Li, Zigeng Qin
      Pages: n/a - n/a
      Abstract: In this paper, a model for gas‐liquid annular and stratified flow through a standard Venturi meter is investigated, by using the two‐phase hydrokinetics theory. The one dimensional momentum equation for gas has been solved in the axial direction of Venturi meters, taking into consideration the factors including the void fraction, the friction between the two phases and the entrainment in the gas core. The distribution of wet gas static pressure between the two pressure tapings of the Venturi meters has been modeled in the pressure range of 0.1 to 0.6 MPa. Compared with the experimental data, all the relative deviations of the predicted points by the model were within ±15%. As the model is less dependent on the specific empirical apparatus and data, it provides the basis for further establishing a flow measurement model of wet gas which will produce fewer biases in results when it is extrapolated. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-18T05:19:58.515141-05:
      DOI: 10.1002/aic.14657
  • Enantioseparation of chiral aromatic acids in process intensified
           liquid‐liquid extraction columns
    • Authors: Alexander Holbach; Julia Godde, Ramanan Mahendrarajah, Norbert Kockmann
      Pages: n/a - n/a
      Abstract: Enantioselective liquid‐liquid extraction (ELLE) is a powerful alternative to common technologies for separation of racemic mixtures. This paper describes the first application of ELLE for aromatic acids in liquid‐liquid extraction columns. The ELLE is investigated experimentally and theoretically for phenylsuccinic acid (PSA) as a representative for aromatic acids. A racemic mixture of (R/S)‐PSA is separated with hydroxypropyl‐ß‐cyclodextrin (HP‐ß‐CD) as selector molecule. The ELLE obtained the highest operative selectivity (αop = 1.8 – 2) for low pH‐values and temperatures. Because of the low operative selectivity, a counter‐current process is necessary to separate both enantiomers completely. The counter‐current process is investigated in process intensified extraction columns (PIECs) (Øin=15 mm) with a high number of equilibrium stages. The experiments demonstrate a good symmetric separation with an enantiomeric excess of 60 % and yields of 80 % for both enantiomers. Finally, the back extraction is investigated to recycle the selector molecule and increase the efficiency. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-18T05:19:55.483082-05:
      DOI: 10.1002/aic.14654
  • Parallel models for arborescent polyisobutylene synthesized in batch
    • Authors: Yutian R. Zhao; Kimberley B. McAuley, Judit E. Puskas
      Pages: n/a - n/a
      Abstract: A mathematical model is developed for estimating kinetic parameters that influence the production of arborescent polyisobutylene via carbocationic copolymerization of inimer and isobutylene. Six different propagation rate constants arise due to the two types of vinyl groups and three types of carbocations. These six parameters are estimated using parallel simulation systems in PREDICI that track i) functional groups, ii) internal and dangling segments in the polymer and iii) concentrations of inimer and polymer molecules. Parameter estimates obtained using the proposed model result in a better fit to literature data than was obtained using a previous model that neglected two types of propagations reactions. Predictions from the proposed model are consistent with Monte Carlo simulations for MWD of the internal and dangling segments. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-18T05:19:49.832353-05:
      DOI: 10.1002/aic.14655
  • Synthesis of optimal thermal membrane distillation networks
    • Authors: Ramón González‐Bravo; Madhav Nyapathi, Nesreen Elsayed, Fabricio Nápoles‐Rivera, José María Ponce‐Ortega, Mahmoud M. El‐Halwagi
      Pages: n/a - n/a
      Abstract: Thermal membrane distillation (TMD) is an emerging separation method which involves simultaneous heat and mass transfer through a hydrophobic semi‐permeable membrane. Traditionally, studies of this technology have focused on the performance of individual modules. Because of purity and recovery requirements, multiple TMD modules may be used in various configurations including series, parallel, and combinations. Furthermore, there may be a need to reroute streams from one module to another or to recycle a stream to the same unit. The objective of this paper is to develop a systematic approach to synthesize an optimal TMD network. A structural representation is developed to embed potential configurations of interest. A mathematical formulation is developed to transform the design problem into an optimization task that seeks to minimize the cost of the system. Two case studies are presented to illustrate the applicability of the developed approach and its merit over conventional design scenarios. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-16T04:33:40.242184-05:
      DOI: 10.1002/aic.14652
  • Sustainable chemical engineering: Dealing with “wicked”
           sustainability problems
    • Authors: Adisa Azapagic; Slobodan Perdan
      Pages: n/a - n/a
      PubDate: 2014-10-16T04:12:33.963518-05:
      DOI: 10.1002/aic.14650
  • Membrane reactor immobilized with palladium‐loaded polymer nanogel
           for continuous‐flow Suzuki coupling reaction
    • Authors: Hirokazu Seto; Tamami Yoneda, Takato Morii, Tatsuya Murakami, Yu Hoshino, Yoshiko Miura
      Pages: n/a - n/a
      Abstract: A catalytic membrane reactor, which was immobilized with palladium‐loaded nanogel particles, was developed for continuous‐flow Suzuki coupling reaction. Palladium‐loaded membranes were prepared by immobilization of nanogel particles, adsorption of palladium ions, and reduction into palladium(0). The presence of palladium in the membrane was confirmed by the scanning electron microscopy; palladium aggregation was not observed. The catalytic activity of the membrane reactor in continuous‐flow Suzuki coupling reaction was approximately double that of a comparable reactor in which palladium ions were directly adsorbed onto an aminated membrane. This was attributed to the formation of small palladium particles. The reusability in the continuous‐flow system was higher than that in a batch system, and the palladium‐loaded membrane reactor had high long‐term stability. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-16T04:12:33.189128-05:
      DOI: 10.1002/aic.14653
  • Motion and stability of cones in a yield stress fluid
    • Authors: Fiacre Ahonguio; Laurent Jossic, Albert Magnin
      Pages: n/a - n/a
      Abstract: This experimental study focuses on the creeping flow of a shear thinning yield stress fluid around conical obstacles. The flow has been analyzed in steady state and with adherence conditions. Firstly, the influences of the cone apex angle and of the Oldroyd number, i.e. the ratio between plastic and viscous effects, on the drag coefficient have been analyzed. Correlations have been proposed to model the evolution of this coefficient as a function of these two parameters. The analysis provides a new alternative for measuring the yield stress. Then, the kinematic fields around the cones have been analyzed. These fields enable to describe the rigid zones and the sheared zone developing around the lateral edge of the cones as a function of the cone apex angle. Moreover, the wall shear stresses estimated from the PIV measurements have enabled to quantify the contribution of the lateral drag force in the drag force. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-14T22:11:44.952325-05:
      DOI: 10.1002/aic.14651
  • Comparative study on electrical properties of copper
           nanowire/polypropylene and carbon nanotube/polypropylene composites
    • Authors: Yan Li; Uttandaraman Sundararaj
      Pages: n/a - n/a
      Abstract: Nanocomposites using copper nanowires (CuNWs) or carbon nanotubes (CNTs) as fillers with polypropylene (PP) as matrix were prepared by miscible solution mixing and precipitation method. Comparative studies on electrical conductivity and electromagnetic interference shielding properties were reported. On the conductivity curve, a plateau was found for both CuNW/PP composite and CNT/PP composite. The plateaus are located at a different concentration range for each composite type: for CuNW/PP composite, it is between 0.8 and 1.7 vol %, while for CNT/PP composite the plateau occurs in a narrower range between 0.4 and 0.6 vol %. The shielding effectiveness (SE) increases with increased concentration of fillers. CNT/PP composite has higher SE at concentrations less than 2 vol %; the two curves cross near 10 dB at this point and at concentrations higher than 2 vol %, CuNW/PP composite has higher SE. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-10T10:23:41.968034-05:
      DOI: 10.1002/aic.14646
  • Sensor network design for maximizing process efficiency: An algorithm and
           its application
    • Authors: Prokash Paul; Debangsu Bhattacharyya, Richard Turton, Stephen E. Zitney
      Pages: n/a - n/a
      Abstract: Sensor network design is a constrained optimization problem requiring systematic and effective solution algorithms for determining where best to locate sensors. In this work, a sensor network design (SND) algorithm is developed for maximizing plant efficiency for an estimator‐based control system while simultaneously satisfying accuracy requirements for the desired process measurements. The SND problem formulation leads to a mixed integer nonlinear programming (MINLP) optimization that is difficult to solve for large‐scale system applications. Therefore, a sequential approach is developed to solve the MINLP problem where the integer problem for sensor selection is solved using the genetic algorithm while the nonlinear programming problem including convergence of the ‘tear stream' in the estimator‐based control system is solved using the direct substitution method. The SND algorithm is then successfully applied to a large‐scale, highly integrated chemical process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-10T03:14:10.892507-05:
      DOI: 10.1002/aic.14649
  • Hydrodynamics, mass transfer and photocatalytic phenol selective oxidation
           reaction kinetics in fixed TiO2 microreactor
    • Authors: M. Krivec; A. Pohar, B. Likozar, G. Dražić
      Pages: n/a - n/a
      Abstract: Photocatalytic phenol dissociation was studied in a microreactor, with a TiO2 layer immobilized on the reactor inner walls. Experiments were conducted for various residence times, initial concentrations, pH values and UV light irradiation intensities. The intermediates and products (catechol, hydroquinone and resorcinol) were quantitatively investigated in order to determine the predominant reaction pathways for the investigated anatase catalyst. A 3D mathematical model was used to simulate the heterogeneous photocatalysis reaction conditions with Langmuir–Hinshelwood mechanism, considering the adsorption/desorption thermodynamic equilibria, and for kinetic parameter estimation via regression analysis. The effectiveness factor, Thiele modulus and the correction function were calculated to determine the pore diffusion effects. The value of pH had the dramatic effect of lowering the reaction rate due to the competitive adsorption of hydroxide ions and protons on the catalyst surface. A phenol conversion of 79.5% was achieved at the residence time of 7.22 min, but without total mineralization. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-07T10:03:11.572969-05:
      DOI: 10.1002/aic.14648
  • Air‐promoted adsorptive desulfurization of diesel fuel over
           Ti‐Ce mixed metal oxides
    • Authors: Jing Xiao; Siddarth Sitamraju, Yongsheng Chen, Shingo Watanabe, Mamoru Fujii, Michael Janik, Chunshan Song
      Pages: n/a - n/a
      Abstract: This work investigates air‐promoted adsorptive desulfurization (ADS) of commercial diesel fuel over a Ti‐Ce mixed oxide adsorbent in a flow system. The fresh/spent adsorbents were characterized using X‐ray absorption near edge structure spectroscopy. Results show that sulfoxide species are formed during air‐promoted ADS over Ti0.9Ce0.1O2 adsorbent. Adsorption selectivity of various compounds in fuel follows the order of dibenzothiophene sulfone > dibenzothiophene ≃ benzothiophene > 4‐methyldibenzothiophene > 4,6‐dimethyldibenzothiophene > phenanthrene > methylnaphthalene > fluorene > naphthalene. The high adsorption affinity of sulfoxide/sulfone is attributed to stronger Ti‐OSR2 than Ti‐SR2 interactions, resulting in significantly enhanced ADS capacity. Adsorption affinity was calculated using ab initio methods. For Ti‐Ce mixed oxides, reduced surface sites lead to O‐vacancy sites for O2 activation for oxidizing thiophenic species. Low temperature is preferred for air‐promoted ADS, and the Ti‐Ce adsorbent can be regenerated via oxidative air treatment. This study paves a new path of designing regenerable adsorbents. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-07T10:02:53.762758-05:
      DOI: 10.1002/aic.14647
  • An improved methodology for outlier detection in dynamic data sets
    • Authors: Shu Xu; Michael Baldea, Thomas F. Edgar, Willy Wojsznis, Terrence Blevins, Mark Nixon
      Pages: n/a - n/a
      Abstract: A time series Kalman filter (TSKF) is proposed that successfully handles outlier detection in dynamic systems, where normal process changes often mask the existence of outliers. The TSKF method combines a time series model fitting procedure with a modified Kalman filter to deal with additive outlier (AO) and innovational outlier (IO) detection problems in dynamic process data set. Compared with current outlier detection methods, the new method enjoys the following advantages: (a) no prior knowledge of the process model is needed; (b) it is easy to tune; (c) it can be applied to both univariate and multivariate outlier detection; (d) it is applicable to both on‐line and off‐line operation; (e) it cleans outliers while maintains the integrity of the original data set. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T03:18:46.156664-05:
      DOI: 10.1002/aic.14631
  • Modeling of continuous self‐classifying spiral jet mills part 2:
           Powder‐dependent parameters from characterization experiments
    • Authors: Derek Starkey; Cathy Taylor, Sunil Siddabathuni, Jinit Parikh, Spyros Svoronos, John Mecholsky, Kevin Powers, Ron Iacocca
      Pages: n/a - n/a
      Abstract: The milling model described in Part 1 has been expanded to a three‐level model with the addition of powder‐dependent parameter function models with simple material characterization measurements as inputs.1 This allows the determination of these parameters with minimal consumption of powder. Specifically, the powder‐dependent parameters are related to material hardness from microindentation or to a breakage measure from single‐impact milling. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the described material characterization techniques and expanded milling model. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T01:37:29.789531-05:
      DOI: 10.1002/aic.14643
  • A new drag correlation from fully resolved simulations of flow past
           monodisperse static arrays of spheres
    • Authors: Y. Tang; S.H.L. Kriebitzsch, E.A.J.F. Peters, M.A. van der Hoef, J.A.M. Kuipers
      Pages: n/a - n/a
      Abstract: We performed fully resolved simulations of flows past fixed assemblies of monodisperse spheres using an iterative Immersed Boundary (IB) Method, for both face‐centered‐cubic (FCC) array and random configurations. For the latter, a methodology has been applied such that the computed gas‐solid force is almost independent of the grid resolution. Simulations in this work extend the previously similar studies to a wider range of solids volume fraction (φЄ[0.1, 0.6]) and Reynolds number (ReЄ[50, 1000]). We propose a new drag correlation combining the existed drag correlations for low‐Re flows and single‐sphere flows, which fits the entire data set with an average relative deviation of 4%. This correlation is so‐far the best possible expression for the drag force in monodisperse static arrays of spheres, and is the most accurate basis to introduce the particle mobility for dynamic gas‐solid systems, such as in fluidized beds. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T01:15:58.54105-05:0
      DOI: 10.1002/aic.14645
  • A multiple radioactive particle tracking technique to investigate
           particulate flows
    • Authors: Majid Rasouli; Francois Bertrand, Jamal Chaouki
      Pages: n/a - n/a
      Abstract: Radioactive particle tracking is a nonintrusive technique that has been successfully employed to study the flow dynamics in a wide range of reactors and blenders. However, it is still limited to the tracking of only one tracer at a time. This article introduces a multiple radioactive particle tracking technique (MRPT) that can determine the trajectory of two free or restricted (attached to the same particle) moving tracers in a system. The accuracy (
      PubDate: 2014-10-06T01:15:45.07222-05:0
      DOI: 10.1002/aic.14644
  • Modeling of Continuous Self‐Classifying Spiral Jet Mills Part 1:
           Model Structure and Validation Using Mill Experiments
    • Authors: Derek Starkey; Cathy Taylor, Nathan Morgan, Katie Winston, Spyros Svoronos, John Mecholsky, Kevin Powers, Ron Iacocca
      Pages: n/a - n/a
      Abstract: The objective of this work is to develop a milling model for a continuous self‐classifying spiral air jet mill.1 Its foundation is a population balance model with selection and breakage distribution functions that have been related to a minimal number of mill‐dependent and powder‐dependent parameters. Initially, experimentation is required to determine the mill‐dependent parameters for a specific mill, by milling a “base” powder at multiple operating conditions. Powder‐dependent parameters can be determined from either mill experiments or from material characterization measurements that require small amounts of powder (presented in Part 2). Ultimately, the milling model presented successfully predicts the product particle size using as inputs the feed particle size distribution and mill operating conditions. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the proposed milling model. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-04T03:29:30.11227-05:0
      DOI: 10.1002/aic.14642
  • Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation
           toward hydrogen purification
    • Authors: Zhongkui Zhao; Jinhan Lin, Guiru Wang, Turghun Muhammad
      Pages: n/a - n/a
      Abstract: Co‐Mn‐O composite oxide nanosheet catalyst was successfully prepared by using a facile urea‐assisted one‐step hydrothermal method in the absence of organic or organic templating reagent. Co‐Mn‐O nanosheet catalyst was optimized by varying hydrothermal process parameters such as molar ratio of Co‐Mn to urea, hydrothermal temperature, and hydrothermal time. Various characterization techniques including scanning electron microscopy, X‐ray diffraction, nitrogen adsorption, X‐ray photoelectron spectroscopy, Raman spectroscopy and H2 temperature‐programmed reduction were employed to reveal the relationship between catalyst nature and catalytic performance in CO preferential oxidation in excess H2. The developed Co‐Mn‐O nanosheet catalyst have demonstrated much superior catalytic performance to Co‐Mn‐O nanoparticle, particularly in the low temperature range, and 100% CO conversion over the developed Co‐Mn‐O nanosheet can be achieved in temperature range of 50 to 150 oC at 10,000 ml g‐1 h‐1 of gas hourly space velocity in the standard feed. Furthermore, the almost complete CO removal over Co‐Mn‐O nanosheet at 125 oC of low temperature with 94.9% selectivity can be achieved even in the simulated reformed gas. The excellent catalytic performance is ascribed to nanosheet morphology, more surface Co3+, smaller average crystallite size, higher reducibility, and strong Co‐Mn interaction. Catalytic stability investigation indicates the developed nanostructured catalyst exhibits high catalytic stability for CO PROX reaction in simulated gas. The developed Co‐Mn‐O nanosheet catalyst can be a potential candidate for catalytic elimination of trace CO from H2‐rich gas for PEMFC applications. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-04T03:09:13.155962-05:
      DOI: 10.1002/aic.14641
  • Protic ionic liquids for the selective absorption of H2S from CO2:
           Thermodynamic analysis
    • Authors: Kuan Huang; Xiao‐Min Zhang, Yun Xu, You‐Ting Wu, Xing‐Bang Hu
      Pages: n/a - n/a
      Abstract: The solubilities of H2S and CO2 in four protic ionic liquids (PILs) ‐ methyldiethanolammonium acetate, methyldiethanolammonium formate, dimethylethanolammonium acetate and dimethylethanolammonium formate were determined at 303.2~333.2K and 0~1.2bar. It is shown PILs have higher absorption capacity for H2S than normal ILs and the Henry's law constants of H2S in PILs (3.5~11.5bar at 303.2K) are much lower than those in normal ILs. In contrast, the solubility of CO2 in PILs is found to be a magnitude lower than that of H2S, implying these PILs have both higher absorption capacity for H2S and higher ideal selectivity of H2S/CO2 (8.9~19.5 at 303.2K) in comparison with normal ILs. The behavior of H2S and CO2 absorption in PILs is further demonstrated based on thermodynamic analysis. The results illustrate that PILs are a kind of promising absorbents for the selective separation of H2S/CO2 and believed to have potential use in gas sweetening. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T07:03:00.090805-05:
      DOI: 10.1002/aic.14634
  • APOD‐based control of linear distributed parameter systems under
           sensor/controller communication bandwidth limitations
    • Authors: Davood Babaei Pourkargar; Antonios Armaou
      Pages: n/a - n/a
      Abstract: The synthesis of a model‐based control structure for general linear dissipative distributed parameter systems (DPSs) is explored in this manuscript. Discrete‐time distributed state measurements (called process snapshots) are employed by a continuous‐time regulator to stabilize the process. The main objective of this paper is to identify a criterion to minimize the communication bandwidth between sensors and controller (snapshots acquisition frequency) using linear systems analysis and still achieve closed‐loop stability. This objective is addressed by adding a modeling layer to the regulator. Theoretically DPSs can be well described by low dimensional ODE models when represented in functional spaces; practically, the model accuracy hinges on finding basis functions for these spaces. Adaptive proper orthogonal decomposition is employed to identify statistically important basis functions and establish locally accurate reduced order models which are then used in controller design. The proposed approach is successfully applied towards thermal regulation in a tubular chemical reactor. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:34:05.396465-05:
      DOI: 10.1002/aic.14640
  • Kinetic Study of the Competitive Hydrogenation of Glycolaldehyde and
           Glucose on Ru/C with or without AMT
    • Authors: Junying Zhang; Baolin Hou, Aiqin Wang, Zhenlei Li, Hua Wang, Tao Zhang
      Pages: n/a - n/a
      Abstract: The competitive hydrogenation of glycolaldehyde and glucose over 1%Ru/C catalyst was studied in a batch reactor at 373‐403 K and 6 MPa hydrogen pressure, with or without the presence of ammonium metatungstate (AMT). It was found that the presence of AMT retarded significantly the hydrogenation of both aldoses, and this suppressing effect was more pronounced on the glucose hydrogenation. The hydrogenation of glycolaldehyde occurred always preferentially to the glucose hydrogenation, with or without the presence of AMT. The kinetic data in the absence of AMT were well modeled based on Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) kinetics assuming the surface reaction being rate‐determining and non‐competitive adsorption of dissociatively chemisorbed hydrogen and aldose. However, in the presence of AMT, the complexing between AMT and aldose and the strong adsorption of AMT on Ru surface must be considered in the development of new kinetic model. The as‐modified model described the data satisfactorily. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:33:12.979792-05:
      DOI: 10.1002/aic.14639
  • Kinetic modeling of Fe‐BEA as NH3‐SCR catalyst – Effect
           of Phosphorous
    • Authors: Soran Shwan; Jonas Jansson, Louise Olsson, Magnus Skoglundh
      Pages: n/a - n/a
      Abstract: The focus of this work is to investigate whether a previously developed micro‐kinetic deactivation model for hydrothermally treated Fe‐BEA as NH3‐SCR catalyst can be applied to describe chemical deactivation of Fe‐BEA due to phosphorous exposure. The model describes the experiments well for Fe‐BEA before and after phosphorous exposure by decreasing the site density, representing deactivation of sites due to formation of metaphosphates blocking the active iron sites, while the kinetic parameters are kept constant. Furthermore, the results show that the activity for low‐temperature SCR is very sensitive to loss of active monomeric iron species due to phosphorous poisoning compared to high‐temperature SCR. Finally, the ammonia inhibition simulations show that exposure to phosphorous may affect the internal transport of ammonia between ammonia storage sites buffering the active iron sites which results in a lower SCR performance during transient conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:31:23.081017-05:
      DOI: 10.1002/aic.14638
  • Development of a Fluidized Bed Thermo‐Gravimetric Analyzer
    • Authors: Said Samih; Jamal Chaouki
      Pages: n/a - n/a
      Abstract: A new fluidized bed thermo‐gravimetric analyzer (FB‐TGA) was developed that introduces two major particularities: the pseudo variation of the weight of the reactor and the special strategy for gas flow rate adjustment according to temperature. A momentum balance was performed on the reactor and the pseudo variation of the reactor weight was evaluated by measuring the pressure drop through the gas distributor and filter. The real weight loss of the reactor was obtained by subtracting the pseudo variation of the weight from the total weight loss measured by the load cell. In addition, a special program for the gas flow rate as a function of temperature was developed and used; so the minimum fluidization regime is maintained throughout all of the experiments. The validation test of the Fluidized Bed TGA was carried out on calcium hydroxide decomposition and the results were compared with those obtained from the conventional TGA. Diffusion control was suppressed by the application of the Fluidized Bed TGA, which was confirmed by the X‐Ray Diffraction (XRD) analysis on the treated samples. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-27T03:34:36.379465-05:
      DOI: 10.1002/aic.14637
  • Spouting behaviors of binary mixtures of cylindroid and spherical
    • Authors: Xuejiao Liu; Wenqi Zhong, Xiaofeng Jiang, Baosheng Jin
      Pages: n/a - n/a
      Abstract: Spouting behaviors of cylindroid and spherical particles in a spouted bed are experimentally investigated. The characteristics of flow pattern and pressure drop of the binary mixtures are figured out and three kinds of cylindroid particles with different sizes and shapes are involved in experiments to discuss effects of particle size and shape on the spouting behaviors in beds. The emphasis is laid on the influence of the volume fraction of cylindroid particles, Xc, on the spouting phenomena, including the total pressure drop, the minimum spouting velocity and fountain height. Results show that, the shapes and sizes of cylindroid particles, mainly including equi‐volume diameter and aspect ratio, significantly affect the spouting behaviors. There is a maximum volume fraction, Xc,max, for each kind of cylinders to maintain the stable fountain at a certain gas velocity. With the same gas velocity, Xc,max is lower for the cylinders with higher aspect ratio. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-26T03:17:39.249733-05:
      DOI: 10.1002/aic.14636
  • Systematic study on heat transfer and surface hydrodynamics of a vertical
           heat tube in a fluidized bed of FCC particles
    • Authors: Xiuying Yao; Xiao Han, Yongmin Zhang, Chunxi Lu
      Pages: n/a - n/a
      Abstract: Bed‐to‐wall heat transfer properties of a vertical heat tube in a fluidized bed of fine FCC particles are measured systematically using a specially designed heat tube. Two important surface hydrodynamic parameters, i.e. the packet fraction (δpa) and mean packet residence time (τpa) based on the packet renewal theory, are determined by an optical fiber probe and a data processing method. The experimental results successfully reveal the axial and radial profiles of heat transfer coefficient, the effects of superficial gas velocity and static bed height on heat transfer coefficient, most of which can be explained successfully by the measured τpa, an indicator of packet renewal frequency. τpa is found to play a more dominant role than δpa on bed‐to‐wall heat transfer. With a fitted correction factor, the modified Mickley & Fairbanks model is able to predict the heat transfer coefficients with enough accuracy based on the determined packet parameters. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-26T03:16:27.713727-05:
      DOI: 10.1002/aic.14635
  • Role of block copolymer on the coarsening of morphology in polymer blend:
           Effect of micelles
    • Authors: Chongwen Huang; Wei Yu
      Pages: n/a - n/a
      Abstract: The reactive compatibilization of polystyrene/ ethylene‐α‐octene copolymer (PS/POE) blend via Friedel‐Crafts alkylation reaction was investigated by rheology and electron microscope. It was found that the graft copolymer formed from interfacial reaction reduced the domain size and decreased the coarsening rate of morphology. The reduction of the interfacial tension is very limited according to the mean field theory even assuming that all block copolymer stays on the interface. With the help of self‐consistent flied theory and rheological constitutive models, the distribution of graft copolymer was successfully estimated. It was found that large amount of copolymer had detached from the interfaces and formed micelles in the matrix. Both the block copolymer micelles in matrix and the block copolymers at the interface contribute to the suppression of coarsening in polymer blend, but play their roles at different stages of droplet coalescence. In droplet morphology, the micelles mainly hinder the approaching of droplets. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-25T04:46:23.069886-05:
      DOI: 10.1002/aic.14633
  • Reaction Kinetics and Mechanism of Catalyzed Hydrolysis of Waste PET Using
           Solid Acid Catalyst in Supercritical CO2
    • Authors: Xue‐Kun Li; Hui Lu, Wen‐Ze Guo, Gui‐Ping Cao, Hong‐Lai Liu, Yun‐Hai Shi
      Pages: n/a - n/a
      Abstract: Hydrolysis of waste PET using solid acid catalyst in SCCO2 is presented in this work for the first time. The mechanism of PET chains scission was proved to be a combination of chain end and random chain scission by FT‐IR and titration analysis. A new reaction kinetics model of PET hydrolysis in SCCO2 was set up by introducing the Arrhenius equation into an ordinary reaction rate equation, the frequency factor and apparent activation energy were expressed in terms of temperature and CO2 pressure, respectively. With this reaction kinetics model, the effects of temperature, and pressure were investigated. An interesting mechanism was proposed to describe the reaction process that both water molecules and hydroniums were carried and penetrated into the amorphous regions of the swollen PET by SCCO2, subsequently hydrolysis reaction preferentially took place in the amorphous regions of both surface and bulk of PET matrix. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-24T01:54:52.62141-05:0
      DOI: 10.1002/aic.14632
  • Integrated solvent and process design exemplified for a Diels‐Alder
    • Authors: Teng Zhou; Kevin McBride, Xiang Zhang, Zhiwen Qi, Kai Sundmacher
      Pages: n/a - n/a
      Abstract: A new kind of solvent descriptor obtained from quantum chemical calculations is introduced. Group contributions to each solvent descriptor are regressed for 71 UNIFAC groups. A reaction kinetic model is built by correlating a set of experimentally determined reaction rate constants in various solvents with the corresponding theoretical solvent descriptors. Based on the kinetic model and the developed group contribution method, a computer‐aided molecular design (CAMD) problem is formulated and optimal solvents to achieve highest reaction rates are identified. For considering the multiple and complicated effects of solvents on a chemical process, an integrated solvent and process design is performed. Solvent molecular structures and process operations are simultaneously optimized by the formulation and solution of a mixed integer nonlinear program (MINLP). The proposed design methodology is exemplified for a selected Diels‐Alder reaction. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-22T10:05:45.556199-05:
      DOI: 10.1002/aic.14630
  • Effect of Particle Size on Flow and Mixing in a Bladed Granular Mixer
    • Authors: Avik Sarkar; Carl R. Wassgren
      Pages: n/a - n/a
      Abstract: A number of studies have modeled flow and mixing of granular materials using the discrete element method (DEM). In an attempt to reduce computational costs, many of these DEM studies model particles larger than the actual particle size without investigating the implications of this assumption. Using DEM, the influence of the modeled particle size on flow and mixing in a bladed granular mixer is studied. The predicted flow microdynamics, including mixing rates, are strongly dependent on the particle diameter. The effect of particle size on macroscopic advective flow also is significant, particularly for dilute flow regions. These results suggest that the influence of particle size needs to be taken into consideration when using larger particles in DEM mixing simulations. To guide scale‐up efforts, particle‐size‐based scaling relationships for several key flow measurements are presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-19T03:07:17.654639-05:
      DOI: 10.1002/aic.14629
  • Engineering Acidithiobacillus ferrooxidans growth media for enhanced
           electrochemical processing
    • Authors: Xiaozheng Li; Roel Mercado, Sarah Berlinger, Scott Banta, Alan C. West
      Pages: n/a - n/a
      Abstract: The chemolithoautotroph A. ferrooxidans has been proposed as a potential electrofuel synthetic platform, and its growth medium is engineered to increase its conductivity and energy density, thereby improving viability of the process. The ion V3+ is used as an indirect electron supplier together with Fe2+ to grow A. ferrooxidans to increase the energy density of the medium, overcoming the Fe3+ solubility limit. A medium containing 10 mM Fe2+ with 60 mM V3+ was able to support cell growth to a final cell concentration very similar to medium of 70 mM Fe2+. Integration of the biological process with an electrochemical reactor requires, for economical operation, a medium with high ionic conductivity. This is achieved by the addition of salt, and Mg2+ was found to be least toxic to the bacterium. A concentration of 500 mM Mg2+ is optimal considering constraints on bacterial growth and electrochemistry. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T03:48:54.727058-05:
      DOI: 10.1002/aic.14628
  • A General and Robust Approach for Defining and Solving Microkinetic
           Catalytic Systems
    • Authors: Gabriel S. Gusmão; Phillip Christopher
      Pages: n/a - n/a
      Abstract: Recent approaches for the rational design of heterogeneous catalysts have relied on first‐principles based microkinetic modeling to efficiently screen large phase spaces of catalytic materials for optimal activity and selectivity. Microkinetic modeling allows the calculation of catalytic rate and selectivity under a given set of conditions without a priori assumptions of rate or selectivity controlling steps by simultaneously solving non‐linear algebraic equations comprising species mass balances bound by the pseudo steady state approximation. We introduce a general approach to define and solve microkinetic systems that relies solely on its stoichiometric matrix and kinetic parameters of considered reaction steps. Our approach relies on linearization of the microkinetic system, enabling analytical calculation of system derivatives for use in quasi‐Newton solution schemes that exhibit excellent robustness and efficiency with minimal dependence on initial conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T02:00:55.601826-05:
      DOI: 10.1002/aic.14627
  • Introducing vapor recompression mechanism in heat integrated distillation
           column (HIDiC): Impact of internal energy driven intermediate and bottom
    • Authors: Bandaru Kiran; Amiya K. Jana
      Pages: n/a - n/a
      Abstract: This work proposes a novel combination of internally heat integrated distillation column (HIDiC) and vapor recompression column (VRC) with intermediate reboiler (IR). Supplying heat at the highest temperature point (i.e., column bottom) of the VRC scheme is not thermodynamically favorable and therefore, we aim to install the IR for better distribution of heat along the column length, thereby reducing the compressor work. Introducing IR in the combined HIDiC‐VRC system, the present work formulates an open‐loop variable manipulation policy to evaluate the comparative impact of internal and external heat sources on bottom liquid reboiling. With internal energy driven bottom reboiler, we further investigate the hybrid HIDiC‐VRCIR column with proposing the two modes of compressor arrangement, namely parallel and series. Finally, a multicomponent distillation system is exampled to show the promising potential of the proposed HIDiC‐VRCIR configurations in improving the energetic and economic performance over the HIDiC‐alone and HIDiC‐VRC schemes with reference to a conventional standalone column. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T11:20:40.502851-05:
      DOI: 10.1002/aic.14620
  • 1H‐ and 13C‐NMR Spectroscopic Study of Chemical Equilibria in
           the System Acetaldehyde + Water
    • Authors: Andreas Scheithauer; Thomas Grützner, Christiaan Rijksen, Daniel Zollinger, Erik von Harbou, Werner R. Thiel, Hans Hasse
      Pages: n/a - n/a
      Abstract: Acetaldehyde is an important intermediate in the chemical industry and often used in mixtures with water. These mixtures are reactive multicomponent systems, as acetaldehyde forms oligomers with water. Quantitative studies of the resulting speciation are scarce in the literature and limited to the formation of the smallest oligomer, ethane‐1,1‐diol. Therefore, in the present work, a comprehensive study of chemical equilibria in mixtures of acetaldehyde and water was carried out by quantitative 1H‐ and 13C‐NMR spectroscopy. The study covers temperatures between 275 and 338 K and overall acetaldehyde mole fractions between about 0.05 and 0.95 mol/mol. The peak assignment is given for both the 1H‐ and 13C‐NMR spectra. From the speciation data, obtained from the peak area fractions, numbers for the chemical equilibrium constants of the oligomer formation are obtained and a correlation is presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T04:06:19.379465-05:
      DOI: 10.1002/aic.14623
  • Kinetics of formation of oil‐in‐water emulsions using in situ
           rheo‐optical measurements
    • Authors: Rudy Covis; Christophe Baravian, Emmanuelle Marie, Alain Durand
      Pages: n/a - n/a
      Abstract: The kinetics of mechanical emulsification in vane geometry was investigated using an original rheo‐optic device. Hexadecane‐in‐water micronic emulsions were prepared using a nonionic polymeric surfactant (Brij700®) as stabilizer. The viscosity of aqueous phase was adjusted using a commercial viscosifier (Emkarox®) which ensured Newtonian behavior to the continuous phase. The influences of two variables (rotational speed and oil volume fraction) on the kinetics of droplet fragmentation were examined in detail. Rotational speed was varied between 50 and 100 rad.s‐1 and had a strong effect on the kinetics of emulsion formation which was discussed on the basis of droplet fragmentation by shear forces. On the contrary, oil volume fraction (between 20 and 60 % v/v) showed no marked effect, which appeared as an important result for scale up considerations. A theoretical description of fragmentation mechanism was proposed and experimental results were compared to calculated values. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T03:58:15.289281-05:
      DOI: 10.1002/aic.14626
  • The generation of hydroxyl radicals by hydrogen peroxide decomposition on
           FeOCl/SBA‐15 catalysts for phenol degradation
    • Authors: Xue‐jing Yang; Peng‐fei Tian, Xiao‐man Zhang, Xin Yu, Ting Wu, Jing Xu, Yi‐fan Han
      Pages: n/a - n/a
      Abstract: Iron oxychloride (FeOCl) supported on mesoporous silica (SBA‐15), as a Fenton‐like solid catalyst for phenol degradation, showed supreme activity for production of hydroxyl radical (HO·) by H2O2 decomposition, and the generation capacity was comparable to the conventional Fenton reagent (Fe2++H2O2). The structure of FeOCl was characterized with multi spectroscopies. The generation of HO· species during the reaction was detected using 5,5‐ dimethyl‐1‐pyrroline N‐ oxide (DMPO) trapped electron paramagnetic resonance (EPR). Furthermore, the kinetics in detail was driven for the creation and diffusion of HO· by H2O2 decomposition over FeOCl, which follows a first‐order rate through a two‐step reaction. With the combination of the catalyst structure and kinetic parameters, the plausible mechanism for H2O2 decomposition during the oxidative degradation of phenol was rationalized. As a Fenton‐like solid catalyst, FeOCl/SBA‐15 is a promising alternative for the removal of low‐level organic contaminates from water. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-12T12:13:28.25-05:00
      DOI: 10.1002/aic.14625
  • Continuum approximation of large reaction mixtures in reactors with
    • Authors: Teh C. Ho; Benjamin S. White
      Pages: n/a - n/a
      Abstract: The growing need to produce ultra‐clean fuels from hydrocarbon mixtures such as petroleum fractions and residues has put increasing pressure on refiners to achieve deep conversions. It is imperative to be able to predict the behavior of such mixtures at high conversions as functions of their properties and reactor type. To this end, treating the reaction mixture as a continuum greatly simplifies the analysis and modeling of the conversion process. However, the continuum approximation can become invalid at very high conversions. Previously, we examined the validity of the approximation for various reactions in plug flow reactors. The present work develops validity conditions for first‐order reaction mixtures in reactors with different mixing intensities. In general, backmixing widens the range of validity. In certain cases the continuum approximation is valid at arbitrarily high conversions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T09:47:24.673548-05:
      DOI: 10.1002/aic.14624
  • Quality assurance of Chinese herbal medicines: Procedure for
           multiple‐herb extraction
    • Authors: Yeuk T. Lau; Na Chen, David T. W. Lau, Kam M. Ko, Ka M. Ng, Ping C. Leung, Christianto Wibowo
      Pages: n/a - n/a
      Abstract: A quality assurance (QA) procedure for multiple‐herb extraction, which takes into account the existence of common chemical markers and multiple‐herb‐extraction effects, has been developed for producing Chinese herbal medicines (CHMs) of consistent quality. The experimental method for determining related correlation function of the multiple‐herb‐extraction effect was designed. A systematic solution strategy was also developed to appropriately decompose the multiple‐herb extraction system into several subsystems for obtaining solution(s) and determining the overall behavior of the system. An example of quality assurance of Danshen‐Gegen (DG) decoction was used to demonstrate the QA procedure. An H9c2 cell assay was used to test the efficacy of consistent quality DG decoctions prepared by different herb combinations with different material costs of herbs. It was observed that a multiple‐herb‐extraction effect was present in the aqueous extraction of Danshensu and this effect was depended on the extraction solvent. The possible mechanism of this multiple‐herb‐extraction effect in the aqueous DG extraction was speculated to be the change of initial pH value of the aqueous extraction solvent by an unknown component from Gegen. The experimental chemical marker concentrations fell within ±10% of the specified chemical marker compositions by using the amount of herb from each herb class as predicted by the QA model. Furthermore, an H9c2 cell assay was used to test the efficacy of three consistent quality DG extracts, which were produced by different herb combinations with different material costs of herbs. The results showed that the three DG extracts provided consistent biological efficacy against menadione‐induced toxicity. This study extended a recently developed QA procedure of single‐herb extraction to multiple‐herb extraction. It provides a solution of quality assurance in extraction, which is one of the most important unresolved problems in the modernization of traditional Chinese medicines. With this modified model and the companion experiments, the amount of herbs needed from different quality classes to produce a multiple‐herb formula CHM product decoction with consistent quality can be exactly determined. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:34:42.636755-05:
      DOI: 10.1002/aic.14619
  • Synthesis of sustainable integrated biorefinery via reaction pathway
           synthesis: Economic, incremental enviromental burden and energy assessment
           with multi‐objective optimization
    • Authors: Viknesh Andiappan; Andy S. Y. Ko, Veronica W. S. Lau, Lik Yin Ng, Rex T. L. Ng, Nishanth G. Chemmangattuvalappil, Denny K. S. Ng
      Pages: n/a - n/a
      Abstract: With the increasing attention toward sustainable development, biomass has been identified as one of the most promising sources of renewable energy. In order to convert biomass into value‐added products and energy, an integrated processing facility, known as an integrated biorefinery is needed. To date, various biomass conversion systems such as gasification, pyrolysis, anaerobic digestion, fermentation, etc. are well established. Due to a large number of technologies available, systematic synthesis of a sustainable integrated biorefinery which simultaneously considers economic performance, environmental impact and energy requirement is a challenging task. In order to address this issue, multi‐objective optimization approaches are used in this work to synthesize a sustainable integrated biorefinery. In addition, a novel approach (incremental environmental burden) to assess the environmental impact for an integrated biorefinery is presented. To illustrate the proposed approach, a palm‐based biomass case study is solved. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-05T04:31:36.584805-05:
      DOI: 10.1002/aic.14616
  • Facile fabrication of spherical architecture of Ni/Al layered double
           hydroxide based on in situ transformation mechanism
    • Authors: Fazhi Zhang; Yue Zhang, Caili Yue, Rong Zhang, Yanmin Yang
      Pages: n/a - n/a
      Abstract: Spherical architectures of nickel‐aluminum layered double hydroxide (NiAl‐LDH) with hydrotalcite‐like nanoflakes as building blocks were facilely fabricated by precipitation reaction in aqueous solution without any surfactants and organic solvents. Growth of such unique structure undergoes preorganization of primary nanospheres of colloidal amorphous aluminum hydroxide (AAH) in solution, followed by nucleation and crystallizaion of LDH from exterior to interior of AAH spheres by an in situ transformation mechanism. The structure and morphology of LDH spheres depend on both starting raw materials and synthetic parameters including reaction time, reaction temperature and aqueous ammonia dosage. NiAl‐LDH sphere as positive electrode material delivers improved rechargeable and discharge‐capacity, with the highest discharge capacity of 173 mAh g‐1 at a current density of 30 mA g‐1 within a potential range from ‐0.1 to 0.45 V in 10 mol L‐1 KOH solution, due to the faster diffusion processes in the spherical architecture than the powder sample. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:45.291152-05:
      DOI: 10.1002/aic.14609
  • Wet dispersion mechanism of fine aggregates in multiphase flow with solid
           beads under simple shear
    • Authors: Daisuke Nishiura; Atsuko Shimosaka, Hide Sakaguchi
      Pages: n/a - n/a
      Abstract: Clarifying the disintegration mechanism of aggregates in multiphase fluid flow coupled with beads and particulates is important for the optimum design of a wet dispersion process using a stirred media mill. Thus, we develop a numerical method for simulating multiphase flow with beads and particulates using a discrete element method and computational fluid dynamics, and we employ the four‐way coupling simulation to study the fluid‐bead‐particulate‐coupled phenomenon that occurs in a simple shear box. The results show that the dominant force causing aggregate disintegration is the fluid force, rather than the bead contact force, because aggregates rarely collide with beads, contact force of which is too small to disintegrate aggregates. Furthermore, aggregates with strong aggregation force are effectively disintegrated by the fluid flow with a dominant high pure‐shear rate induced near the bead surfaces by the expansive force, rather than the compressive force. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:31.247714-05:
      DOI: 10.1002/aic.14614
  • Influence of unsteady mass transfer on dynamics of rising and sinking
           droplet in water: Experimental and CFD study
    • Authors: Abhijit Rao; Rupesh K Reddy, Kalliat T Valsaraj, Krishnaswamy Nandakumar, Shashank Pandey, C. L. Wu
      Pages: n/a - n/a
      Abstract: Experimental and numerical investigations were conducted to study the effect of unsteady mass transfer on the dynamics of an organic droplet released in quiescent water. The situation is important and relevant to deep sea oil spill scenario. The droplet contains two components, one is heavier (immiscible) than water and other is lighter (miscible). When released, with an initial mixture density (890‐975 kg/m3) lower than that of surrounding water, droplet rises in the column. The mass transfer of lighter solute component into water causes the droplet density to increase and droplet sinks when the density exceeds that of water. A mass transfer correlation accounting for the loss of the solute, based on Reynolds, Grashoff and Schmidt numbers was developed. A 2D axisymmetric CFD model accounting for species transport was developed to emulate the experimental observations. The study also helped in identifying dominant mass transfer mechanisms during different stages of droplet motion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T02:56:12.35339-05:0
      DOI: 10.1002/aic.14612
  • UNIFAC model for ionic liquid‐CO (H2) systems: An experimental and
           modeling study on gas solubility
    • Authors: Zhigang Lei; Chengna Dai, Qian Yang, Jiqin Zhu, Biaohua Chen
      Pages: n/a - n/a
      Abstract: The UNIFAC model for ionic liquids (ILs) has become notably popular because of its simplicity and availability via modern process simulation softwares. In this work, new group binary interaction parameters (αmn and αnm) between CO (H2) and IL groups were obtained by correlating the solubility data in pure ILs at high temperatures (above 273.2 K) collected from the literature. We also measured the solubility of CO in [BMIM]+[BF4]‐, [OMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, as well as that of H2 in [EMIM]+[BF4]‐, [BMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, at temperatures from 243.2 to 333.2 K and pressures up to 6.0 MPa. The UNIFAC model was observed to well predict the solubility in pure and mixed ILs at both high (above 273.2 K) and low (below 273.2 K) temperatures. Moreover, the selectivity of CO (or H2) to CO2 in ILs increases with decreasing temperature, indicating that low temperatures favor for gas separation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-28T02:12:45.692518-05:
      DOI: 10.1002/aic.14606
  • Modeling of turbulent cross flow microfiltration of pomegranate juice
           using hollow fiber membranes
    • Authors: Sourav Mondal; Sirshendu De, Alfredo Cassano, Franco Tasselli
      Pages: n/a - n/a
      Abstract: A mathematical analysis of the permeate flux decline during microfiltration of fruit juice with hollow fibers under turbulent flow is presented. Impact of complex fluid flow phenomena on mass transfer is analyzed. A comprehensive analytical model for developing concentration boundary layer was formulated from first principles using integral method. Attempts to model the system considering constant boundary layer thickness (film theory) is inaccurate for developing boundary layer. Gel resistance parameter depending on juice characteristics has significant impact on permeate flux. Specific gel layer concentration has insignificant effect on system performance under total recycle mode but important for batch mode. Theoretical results were compared with experiments in clarification of pomegranate juice with poly(ether ether ketone) and polysulfone hollow fiber membranes. The physical parameters of complex mixture were evaluated by optimizing of the flux profiles in total recycle mode of operation and were successfully applied for prediction of batch mode performance. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T14:31:54.531115-05:
      DOI: 10.1002/aic.14594
  • A novel fluorinated polymeric product for photo‐reversibly
           switchable hydrophobic surface
    • Authors: Yin‐Ning Zhou; Jin‐Jin Li, Qing Zhang, Zheng‐Hong Luo
      Pages: n/a - n/a
      Abstract: In this work, a new chemical product, i.e. photo‐reversibly switchable hydrophobic surface coating, was synthesized by atom transfer radical polymerization (ATRP) 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, 2014
      PubDate: 2014-08-27T09:37:47.887919-05:
      DOI: 10.1002/aic.14602
  • Hybrid FSC Membrane for CO2 Removal from Natural Gas: Experimental,
           Process Simulation and Economic Feasibility Analysis
    • Authors: Xuezhong He; Taek‐Joong Kim, May‐Britt Hägg
      Pages: n/a - n/a
      Abstract: The novel fixed‐site‐carrier (FSC) membranes were prepared by coating carbon nanotubes (CNTs) reinforced polyvinylamine (PVAm)/polyvinylalcohol (PVA) selective layer on top of ultrafiltration polysulfone support. Small pilot‐scale modules with membrane area of 110‐330cm2 were tested with high pressure permeation rig. The prepared hybrid FSC membranes show high CO2 permeance of 0.084~0.218 m3 (STP) / ( with CO2/ CH4 selectivity of 17.9‐34.7 at different feed pressures up to 40 bar for a 10% CO2 feed gas. Operating parameters of feed pressure, flow rate and CO2 concentration were found to significantly influence membrane performance. HYSYS simulation integrated with ChemBrane and cost estimation was conducted to evaluate techno‐economic feasibility of a membrane process for natural gas sweetening. Simulation results indicated that the developed FSC membranes could be a promising candidate for CO2 removal from low CO2 concentration (10%) natural gases with a low natural gas sweetening cost of 5.73E‐3 $ / Nm3 sweet NG produced. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T02:01:53.588201-05:
      DOI: 10.1002/aic.14600
  • CFD Modeling of LPG Vessels under Fire Exposure Conditions
    • Authors: Arianna D’aulisa; Gabriele Landucci, Alessandro Tugnoli, Valerio Cozzani, Albrecht Michael Birk
      Pages: n/a - n/a
      Abstract: Fire exposure of tanks used for the storage and transportation of liquefied gases under pressure may cause complex heat and mass transfer phenomena that may contribute to compromise the integrity of the vessels in accident scenarios. Heat transfer through vessel lading results in the heat‐up of the internal fluid and the increase of vessel internal pressure. However, local temperature gradients in the liquid phase cause liquid stratification phenomena that result in a more rapid vaporization and pressure build‐up in the liquid phase. These fundamental phenomena were analyzed by a Computational Fluid Dynamic (CFD) model. The model was specifically focused on the early steps of vessel heat‐up, when liquid stratification plays a relevant role in determining the vessel internal pressure. A two‐dimensional transient simulation was set up using ANSYS FLUENT in order to predict the evolution of the liquid and vapor phases during the tank heat up. The model was validated against available large scale experimental data available for liquefied petroleum gas (LPG) vessels exposed to hydrocarbon fires, and was applied to case studies derived from recent accidental events in order to assess the expected time of pressure build‐up in different fire scenarios. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T01:54:41.674435-05:
      DOI: 10.1002/aic.14599
  • Minimum entropy generation for isothermal endothermic/exothermic reactor
    • Authors: Paul G. Ghougassian; Vasilios Manousiouthakis
      Pages: n/a - n/a
      Abstract: In our earlier work, it was shown that entropy generation and energy (hot utility or cold utility) consumption of isothermal, isobaric reactor networks depend only on the network’s inlet and outlet stream compositions and flow rates and are not dependent on the reactor network structure, as long as the universe of realizable reactor units and network outlet mixing units are either all endothermic interacting with a single hot reservoir, or all exothermic interacting with a single cold reservoir respectively. In this work, it is shown that when the universe of realizable reactor/mixer units, of isothermal, isobaric, continuous stirred tank reactor networks, consists of both endothermic units interacting with a single hot reservoir and exothermic units interacting with a single cold reservoir, the network’s net (hot minus cold) utility consumption depends only on the network’s inlet and outlet stream compositions and flow rates (and does not depend on the network’s structure). In contrast, the network’s entropy generation depends on the network’s inlet and outlet stream compositions and flow rates, and the network’s hot utility (or cold utility) consumption. The latter, in general, depends on the network structure, thus making entropy generation also, in general, depend on network structure. Thus the synthesis of isothermal, isobaric reactor networks, with fixed inlet and outlet stream specifications, is equivalent to the synthesis of minimum hot (or cold) utility consuming such networks. The Infinite DimEnsionAl State‐space (IDEAS) conceptual framework is employed for the problem’s mathematical formulation, which is then used to rigorously establish the above equivalence. A case study involving Trambouze kinetics demonstrates the findings. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-21T10:56:53.104694-05:
      DOI: 10.1002/aic.14598
  • Global optimality properties of total annualized and operating cost
           problems for compressor sequences
    • Authors: Jeremy A. Conner; Vasilios I. Manousiouthakis
      Pages: n/a - n/a
      Abstract: In this work, the minimum total annualized cost problem is studied for a series of non‐isentropic compressors and coolers that brings a gas with constant compressibility factor from a specified initial pressure and temperature to a specified final pressure and the same temperature. It is established analytically that at the global optimum, the cooler outlet temperatures are equal to the minimum allowable temperature. For constant heat capacity, constant compressibility factor gases, additional properties of the globally optimal compressor sequence are analytically established for the minimum operating cost case. The aforementioned properties permit development of a solution strategy that identifies the globally‐minimum operating cost. Several case studies are presented to illustrate the developed theorems and solution strategies. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T09:40:36.178594-05:
      DOI: 10.1002/aic.14580
  • Influences of loading rate and preloading on the mechanical properties of
           dry elasto‐plastic granules under compression
    • Authors: Alexander Russell; Peter Müller, Hao Shi, Jürgen Tomas
      Pages: 4037 - 4050
      Abstract: To ensure high quality of granular products post‐industrial operations, it is necessary to precisely define their micro–macro mechanical properties. However, such an endeavor is arduous, owing to their highly inhomogeneous, anisotropic and history‐dependent nature. In this article, we present the distributed granular micromechanical and macromechanical, energetic and breakage characteristics using statistical distributions. We describe the material behavior of elastoplastic zeolite 4AK granules under uniaxial compressive loading until primary breakage, and localized cyclic loading up to different maximum force levels, at different displacement‐controlled loading rates. The observed force‐displacement behavior had been approximated and further evaluated using well‐known contact models. The results provide the basis for a detailed analysis of the viscous behavior of zeolite 4AK granules in the moist and wet states, indicating that higher compressive loads are required at higher displacement‐controlled loading rates to realize equivalent deformation and breakage probability achieved by loads at lower displacement‐controlled loading rates. © 2014 American Institute of Chemical Engineers AIChE J 60: 4037–4050, 2014
      PubDate: 2014-08-13T23:11:44.459178-05:
      DOI: 10.1002/aic.14572
  • Measurement of particle concentration in a Wurster fluidized bed by
           electrical capacitance tomography sensors
    • Authors: Ruihuan Ge; Jiamin Ye, Haigang Wang, Wuqiang Yang
      Pages: 4051 - 4064
      Abstract: It is essential to measure and monitor the particle flow characteristics in a Wurster fluidized bed to understand and optimize the coating processes. In this article, two electrical capacitance tomography (ECT) sensors are used to measure the particle concentration in different regions in a Wurster fluidized bed for the “cold” particle flows. One ECT sensor has a 12‐4 internal‐external electrodes and another has eight electrodes. The 12‐4‐electrode ECT sensor is used to measure the particle concentration in the annular fluidization region (outside of the Wurster tube) and the eight‐electrode ECT sensor is used to measure the particle flow in the central region (inside the Wurster tube). The effect of particle type, particle moisture, fluidization velocity, and geometrical parameters on the Wurster fluidization process is studied based on the two ECT measurements. The radial particle concentration profiles in the annular fluidization and central flow regions with different operation parameters are given. Fast Fourier Transform analysis of the particle concentration in the Wurster tube is performed with different superficial air velocities. The optimum operating ranges of the Wurster fluidization process for different particles are given. In the end of the article, computational fluids dynamics simulation results are given and used to compare with the measurement results by ECT for a typical Wurster fluidized bed. © 2014 American Institute of Chemical Engineers AIChE J 60: 4051–4064, 2014
      PubDate: 2014-08-25T20:59:06.104639-05:
      DOI: 10.1002/aic.14595
  • Boundary conditions for collisional granular flows of frictional and
           rotational particles at flat walls
    • Authors: Yunhua Zhao; Yingjie Zhong, Yurong He, H. Inaki Schlaberg
      Pages: 4065 - 4075
      Abstract: Collisions between frictional particles and flat walls are determined using Coulomb friction and both tangential and normal restitution, and pseudothermal states of particles are described by both the translational and rotational granular temperatures. Then, new models for the stresses and the fluxes of fluctuation energy for the collisional granular flows at the walls are derived. These new models are tested and compared with the literature data and models. The ratio of rotational to translational granular temperatures is shown to be crucial on accurately predicting the shear stress and energy flux and is dependent on the normalized slip velocity as well as the collisional parameters. Using a theoretical but constant value for this ratio, predictions by the new models could still agree better with the literature data than those by the previous models. Finally, boundary conditions are developed to be used within the framework of kinetic theory of granular flow. © 2014 American Institute of Chemical Engineers AIChE J 60: 4065–4075, 2014
      PubDate: 2014-08-25T21:08:42.042732-05:
      DOI: 10.1002/aic.14596
  • Equation‐oriented flowsheet simulation and optimization using
           pseudo‐transient models
    • Authors: Richard C. Pattison; Michael Baldea
      Pages: 4104 - 4123
      Abstract: Tight integration through material and energy recycling is essential to the energy efficiency and economic viability of process and energy systems. Equation‐oriented (EO) steady‐state process simulation and optimization are key enablers in the optimal design of integrated processes. A new process modeling and simulation concept based on pseudo‐transient continuation is introduced. An algorithm for reformulating the steady‐state models of process unit operations as differential‐algebraic equation systems that are statically equivalent with the original model is presented. These pseudo‐transient models improve the convergence of EO process flowsheet simulations by expanding the convergence basin. This concept is used to build a library of pseudo‐transient models for common process unit operations, and this modeling concept seamlessly integrates with a previously developed time‐relaxation optimization algorithm. Two design case studies are presented to validate the proposed framework. © 2014 American Institute of Chemical Engineers AIChE J 60: 4104–4123, 2014
      PubDate: 2014-08-16T23:17:10.186817-05:
      DOI: 10.1002/aic.14567
  • Distributed lyapunov‐based model predictive control with
           neighbor‐to‐neighbor communication
    • Authors: Su Liu; Jinfeng Liu
      Pages: 4124 - 4133
      Abstract: This work considers distributed predictive control of large‐scale nonlinear systems with neighbor‐to‐neighbor communication. It fulfills the gap between the existing centralized Lyapunov‐based model predictive control (LMPC) and the cooperative distributed LMPC and provides a balanced solution in terms of implementation complexity and achievable performance. This work focuses on a class of nonlinear systems with subsystems interacting with each other via their states. For each subsystem, an LMPC is designed based on the subsystem model and the LMPC only communicates with its neighbors. At a sampling time, a subsystem LMPC optimizes its future control input trajectory assuming that the states of its upstream neighbors remain the same as (or close to) their predicted state trajectories obtained at the previous sampling time. Both noniterative and iterative implementation algorithms are considered. The performance of the proposed designs is illustrated via a chemical process example. © 2014 American Institute of Chemical Engineers AIChE J 60: 4124–4133, 2014
      PubDate: 2014-08-19T10:17:21.539968-05:
      DOI: 10.1002/aic.14579
  • An integrated qualitative and quantitative modeling framework for
           computer‐assisted HAZOP studies
    • Authors: Jing Wu; Laibin Zhang, Jinqiu Hu, Morten Lind, Xinxin Zhang, Sten Bay Jørgensen, Gürkan Sin, Niels Jensen
      Pages: 4150 - 4173
      Abstract: The article proposes a novel practical framework for computer‐assisted hazard and operability (HAZOP) that integrates qualitative reasoning about system function with quantitative dynamic simulation in order to facilitate detailed specific HAZOP analysis. The practical framework is demonstrated and validated on a case study concerning a three‐phase separation process. The multilevel flow modeling (MFM) methodology is used to represent the plant goals and functions. First, means‐end analysis is used to identify and formulate the intention of the process design in terms of components, functions, objectives, and goals on different abstraction levels. Based on this abstraction, qualitative functional models are constructed for the process. Next MFM‐specified causal rules are extended with systems specific features to enable proper reasoning. Finally, systematic HAZOP analysis is performed to identify safety critical operations, its causes and consequences. The outcome is a qualitative hazard analysis of selected process deviations from normal operations and their consequences as input to a traditional HAZOP table. The list of unacceptable high risk deviations identified by the qualitative HAZOP analysis is used as input for rigorous analysis and evaluation by the quantitative analysis part of the framework. To this end, dynamic first‐principles modeling is used to simulate the system behavior and thereby complement the results of the qualitative analysis part. The practical framework for computer‐assisted HAZOP studies introduced in this article allows the HAZOP team to devote more attention to high consequence hazards. © 2014 American Institute of Chemical Engineers AIChE J 60: 4150–4173, 2014
      PubDate: 2014-08-27T14:17:12.861552-05:
      DOI: 10.1002/aic.14593
  • Analysis of plug flow reactors with variable mass density
    • Authors: James S. Vrentas; Christine M. Vrentas
      Pages: 4185 - 4189
      Abstract: The design of plug flow reactors with variable mass density is examined. Equations which include a two‐term constitutive equation for the reaction rate are derived for the flow of liquids and for the flow of ideal gases in steady plug flow reactors. It is shown that the addition of the second term in the constitutive equation can have a significant effect on the calculation of the reactor volume needed to carry out a specific conversion of the reactant. Published experimental plug flow reactor data support the observation that a reaction rate constitutive equation with two terms can provide a good representation of the experimental data for variable mass density reactors. © 2014 American Institute of Chemical Engineers AIChE J 60: 4185–4189, 2014
      PubDate: 2014-08-13T23:24:54.272362-05:
      DOI: 10.1002/aic.14574
  • Mechanism and kinetic modeling for steam reforming of toluene on
           La0.8Sr0.2Ni0.8Fe0.2O3 catalyst
    • Authors: Usman Oemar; Ang Ming Li, Kus Hidajat, Sibudjing Kawi
      Pages: 4190 - 4198
      Abstract: Reaction mechanism for steam reforming of toluene is proposed for La0.8Sr0.2Ni0.8Fe0.2O3 perovskite catalyst. The proposed mechanism was derived from various characterization results such as temperature‐programmed desorption (TPD) and temperature‐programmed surface reaction (TPSR) water, TPSR toluene, TPD O2 and in situ DRIFT of toluene decomposition, and steam reforming of toluene. Five kinetic models were developed based on the proposed dual‐site reaction mechanism using Langmuir–Hinshelwood approach. Subsequently, the parameters of the kinetic models were estimated by nonlinear least square regression. A good agreement was obtained between experimental and model predicted results for the rate determining step based on reaction between adsorbed aldehyde and adsorbed oxygen. The adsorbed aldehyde species is produced from the reaction between adsorbed C2H2 or CH2 and adsorbed oxygen while the adsorbed oxygen species can come from the oxygen from water activation, lattice oxygen species, and/or the redox property of some metals such as Fe. This shows that the adsorbed oxygen species plays important role in this reaction. © 2014 American Institute of Chemical Engineers AIChE J 60: 4190–4198, 2014
      PubDate: 2014-08-20T16:44:35.908343-05:
      DOI: 10.1002/aic.14573
  • Modified gas‐translation model for prediction of gas permeation
           through microporous organosilica membranes
    • Authors: Hiroki Nagasawa; Takuya Niimi, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
      Pages: 4199 - 4210
      Abstract: A modified gas‐translation (GT) model was applied for the theoretical analysis of gas permeation through microporous organosilica membranes derived from bis(triethoxysilyl)ethane (BTESE) via a sol–gel method using different water/alkoxide molar ratios. The pore sizes of BTESE‐derived membranes were quantitatively determined by normalized Knudsen‐based permeance analysis, which was based on a modified‐GT model, using experimentally obtained permeances of He, H2, N2, C3H8, and SF6. The pore sizes of BTESE‐derived membranes were successfully controlled from 0.65 to 0.46 nm by increasing the H2O/BTESE ratio from 6 to 240. Furthermore, theoretical correlations of all possible pairs of permeance ratios were calculated based on the modified‐GT model. The experimental data were in good agreement with the theoretical correlation curves, indicating that the modified‐GT model can clearly explain gas permeation mechanisms through microporous membranes, and, thus, can be used to predict the gas permeation properties for these membranes. © 2014 American Institute of Chemical Engineers AIChE J 60: 4199–4210, 2014
      PubDate: 2014-08-25T14:28:37.584436-05:
      DOI: 10.1002/aic.14578
  • Analytical models for predicting penetration depth during slot die coating
           onto porous media
    • Authors: Xiaoyu Ding; Joshua Prince Ebin, Tequila A.L. Harris, Zhuo Li, Thomas F. Fuller
      Pages: 4241 - 4252
      Abstract: A series of analytical models have been developed to predict the penetration depth during slot die coating on porous media. Analytical models for both Newtonian and non‐Newtonian fluids were derived based on Lubrication Theory, Darcy's law, and a modified Blake–Kozeny equation. Using these models, the penetration depth can be quickly solved and the effects of material properties and processing conditions on penetration depth can be easily investigated. Experiments of coating Newtonian glycerin and non‐Newtonian blackstrap molasses onto Toray series carbon paper were conducted to validate developed models. The overall relative error between the predicted and measured penetration depth was found to be typically lower than 20%, which demonstrates the relative accuracy of developed models. Furthermore, based on a parametric study, it was found that the effect of capillary pressure on penetration depth is less than 10% when the ratio of coating bead pressure and capillary pressure is larger than 10. © 2014 American Institute of Chemical Engineers AIChE J 60: 4241–4252, 2014
      PubDate: 2014-08-12T13:31:42.859802-05:
      DOI: 10.1002/aic.14570
  • Near‐wall convection in a sedimenting suspension of fibers
    • Authors: Feng Zhang; Anders A. Dahlkild, Katarina Gustavsson, Fredrik Lundell
      Pages: 4253 - 4265
      Abstract: The sedimentation of a fiber suspension near a vertical wall is investigated numerically. Initially, the near‐wall convection is an upward backflow, which originates from the combined effects of the steric‐depleted layer and a hydrodynamically depleted region near the wall. The formation of the hydrodynamically depleted region is elucidated by a convection‐diffusion investigation, in which fibers are classified according to the different directions in which they drift. For fibers with sufficiently large aspect ratio, the initial near‐wall backflow keeps growing. However, the backflow reverses to downward flow at later times if the aspect ratio is small. This is due to the fiber‐wall interactions which rotate fibers to such angles that make fibers drift away from the wall, inducing a dense region and a correspondingly downward flow outside the initial backflow. Moreover, the steric‐depleted boundary condition is of secondary importance in the generation and evolution of the near‐wall convection. © 2014 American Institute of Chemical Engineers AIChE J 60: 4253–4265, 2014
      PubDate: 2014-08-21T10:54:30.136895-05:
      DOI: 10.1002/aic.14576
  • A numerical study of dynamic capillary pressure effect for supercritical
           carbon dioxide‐water flow in porous domain
    • Authors: Diganta B. Das; Bhupinder S. Gill, Luqman K. Abidoye, Kamal J. Khudaida
      Pages: 4266 - 4278
      Abstract: Numerical simulations for core‐scale capillary pressure (Pc)‐saturation (S) relationships have been conducted for a supercritical carbon dioxide‐water system at temperatures between 35°C and 65°C at a domain pressure of 15 MPa as typically expected during geological sequestration of CO2. As the Pc‐S relationships depend on both S and time derivative of saturation ( ∂S/∂t) yielding what is known as the “dynamic capillary pressure effect” or simply “dynamic effect,” this work specifically attempts to determine the significance of these effects for supercritical carbon dioxide‐water flow in terms of a coefficient, namely dynamic coefficient (τ). The coefficient establishes the speed at which capillary equilibrium for supercritical CO2 (scCO2)‐water flow is reached. The simulations in this work involved the solution of the extended version of Darcy's law which represents the momentum balance for individual fluid phases in the system, the continuity equation for fluid mass balance, as well as additional correlations for determining the capillary pressure as a function of saturation, and the physical properties of the fluids as a function of temperature. The simulations were carried out for three‐dimensional cylindrical porous domains measuring 10 cm in diameter and 12 cm in height. τ was determined by measuring the slope of a best‐fit straight line plotted between (1) the differences in dynamic and equilibrium capillary pressures (Pc,dyn−Pc,equ) against (2) the time derivative of saturation (dS/dt), both at the same saturation value. The results show rising trends for τ as the saturation values reduce, with noticeable impacts of temperature at 50% saturation of aqueous phase. This means that the time to attain capillary equilibrium for the CO2‐water system increases as the saturation decreases. From a practical point of view, it implies that the time to reach capillary equilibrium during geological sequestration of CO2 is an important factor and should be accounted for while simulating the flow processes, for example, to determine the CO2 storage capacity of a geological aquifer. In this task, one would require both the fundamental understanding of the dynamic capillary pressure effects for scCO2‐water flow as well as τ values. These issues are addressed in this article. © 2014 American Institute of Chemical Engineers AIChE J 60: 4266–4278, 2014
      PubDate: 2014-08-23T18:05:49.756957-05:
      DOI: 10.1002/aic.14577
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