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  Subjects -> ENGINEERING (Total: 2246 journals)
    - CHEMICAL ENGINEERING (188 journals)
    - CIVIL ENGINEERING (178 journals)
    - ELECTRICAL ENGINEERING (98 journals)
    - ENGINEERING (1191 journals)
    - ENGINEERING MECHANICS AND MATERIALS (386 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (61 journals)
    - MECHANICAL ENGINEERING (89 journals)

ENGINEERING (1191 journals)            First | 1 2 3 4 5 6 | Last

Showing 201 - 400 of 1205 Journals sorted alphabetically
Current Science     Open Access   (Followers: 35)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 5)
Design Journal : An International Journal for All Aspects of Design     Hybrid Journal   (Followers: 26)
Designed Monomers and Polymers     Hybrid Journal  
Designs, Codes and Cryptography     Hybrid Journal   (Followers: 6)
Development Engineering     Open Access  
Developments in Clay Science     Full-text available via subscription   (Followers: 1)
Developments in Geotechnical Engineering     Full-text available via subscription   (Followers: 4)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Diálogos Interdisciplinares     Open Access  
Diffusion Foundations     Full-text available via subscription  
Digital Signal Processing     Hybrid Journal   (Followers: 12)
Discrete Optimization     Full-text available via subscription   (Followers: 5)
Doct-Us Journal     Open Access  
Documents pour l'histoire des techniques     Open Access   (Followers: 1)
Dyes and Pigments     Hybrid Journal   (Followers: 1)
Dyna     Open Access  
Dynamical Systems : An International Journal     Hybrid Journal  
E&S Engineering and Science     Open Access  
El Hombre y la Máquina     Open Access  
Electromagnetics     Hybrid Journal   (Followers: 4)
Electrophoresis     Hybrid Journal   (Followers: 19)
Elementos     Open Access  
Elsevier Geo-Engineering Book Series     Full-text available via subscription   (Followers: 2)
Elsevier Ocean Engineering Series     Full-text available via subscription  
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 38)
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access   (Followers: 1)
Energies     Open Access   (Followers: 3)
Energy and Power Engineering     Open Access   (Followers: 16)
Energy Conversion and Management     Hybrid Journal   (Followers: 8)
Energy Engineering     Full-text available via subscription   (Followers: 9)
Energy for Sustainable Development     Hybrid Journal   (Followers: 9)
Energy Procedia     Open Access   (Followers: 2)
Energy Science & Engineering     Open Access   (Followers: 3)
Energy Science and Technology     Open Access   (Followers: 12)
Energy Sources, Part A: Recovery, Utilization, and Environmental Effects     Hybrid Journal   (Followers: 1)
Energy Sources, Part B: Economics, Planning, and Policy     Hybrid Journal   (Followers: 6)
Energy Systems     Hybrid Journal   (Followers: 12)
ENGEVISTA     Open Access   (Followers: 1)
ENGI : Revista Electrónica de la Facultad de Ingenieria     Open Access  
Engineer : Journal of the Institution of Engineers, Sri Lanka     Open Access  
Engineering     Open Access   (Followers: 1)
Engineering & Technology     Hybrid Journal   (Followers: 22)
Engineering : The official journal of the Chinese Academy of Engineering and Higher Education Press     Open Access   (Followers: 1)
Engineering Analysis with Boundary Elements     Hybrid Journal   (Followers: 1)
Engineering Computations     Hybrid Journal   (Followers: 3)
Engineering Economics     Open Access   (Followers: 4)
Engineering Economist, The     Hybrid Journal   (Followers: 6)
Engineering Failure Analysis     Hybrid Journal   (Followers: 64)
Engineering Geology     Hybrid Journal   (Followers: 8)
Engineering International     Open Access  
Engineering Journal     Open Access   (Followers: 1)
Engineering Management Journal     Hybrid Journal   (Followers: 19)
Engineering Management Research     Open Access   (Followers: 6)
Engineering Management Reviews     Open Access   (Followers: 1)
Engineering Optimization     Hybrid Journal   (Followers: 7)
Engineering Science and Technology, an International Journal     Open Access   (Followers: 1)
Engineering Sciences     Open Access   (Followers: 1)
Engineering Studies     Hybrid Journal  
Engineering With Computers     Hybrid Journal   (Followers: 7)
Engineering, Technology & Applied Science Research     Open Access  
Entramado     Open Access  
Entropy     Open Access   (Followers: 4)
Environmental & Engineering Geoscience     Full-text available via subscription   (Followers: 3)
Environmental and Ecological Statistics     Hybrid Journal   (Followers: 6)
Environmetrics     Hybrid Journal  
Épités - Épitészettudomány     Full-text available via subscription   (Followers: 1)
EPJ Photovoltaics     Open Access   (Followers: 2)
Épsilon     Open Access  
Ergonomics in Design: The Quarterly of Human Factors Applications     Hybrid Journal   (Followers: 13)
ESAIM: Control Optimisation and Calculus of Variations     Full-text available via subscription   (Followers: 1)
ESAIM: Mathematical Modelling and Numerical Analysis     Full-text available via subscription   (Followers: 4)
ESAIM: Proceedings     Open Access  
Estuaries and Coasts     Hybrid Journal   (Followers: 17)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 3)
European Journal of Engineering Education     Hybrid Journal   (Followers: 3)
European Journal of Lipid Science and Technology     Hybrid Journal   (Followers: 1)
European Journal of Mass Spectrometry     Full-text available via subscription   (Followers: 16)
European Medical Device Technology     Full-text available via subscription   (Followers: 3)
European Physical Journal - Applied Physics     Full-text available via subscription   (Followers: 7)
European Transport Research Review     Open Access   (Followers: 21)
Evolutionary Intelligence     Hybrid Journal   (Followers: 1)
Evolving Systems     Hybrid Journal  
Exacta     Open Access  
Experimental Techniques     Hybrid Journal   (Followers: 56)
Experiments in Fluids     Hybrid Journal   (Followers: 10)
Fibers and Polymers     Full-text available via subscription   (Followers: 4)
Filtration & Separation     Full-text available via subscription   (Followers: 4)
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 4)
Fire Science Reviews     Open Access   (Followers: 5)
Flexible Services and Manufacturing Journal     Hybrid Journal   (Followers: 1)
Flow, Turbulence and Combustion     Hybrid Journal   (Followers: 24)
Fluid Dynamics     Hybrid Journal   (Followers: 10)
Fluid Dynamics Research     Full-text available via subscription   (Followers: 10)
Fluid Phase Equilibria     Hybrid Journal   (Followers: 4)
Focus on Catalysts     Full-text available via subscription  
Focus on Pigments     Full-text available via subscription   (Followers: 3)
Focus on Powder Coatings     Full-text available via subscription   (Followers: 3)
Focus on Surfactants     Full-text available via subscription   (Followers: 3)
Food Engineering Reviews     Hybrid Journal   (Followers: 3)
Food Science and Technology     Open Access   (Followers: 3)
Formación Universitaria     Open Access   (Followers: 3)
FORMakademisk     Open Access  
Formal Methods in System Design     Hybrid Journal   (Followers: 6)
Forschung     Hybrid Journal  
Forschung im Ingenieurwesen     Hybrid Journal   (Followers: 1)
Foundations and Trends in Systems and Control     Full-text available via subscription  
Foundations and Trends® in Communications and Information Theory     Full-text available via subscription   (Followers: 7)
Foundations and Trends® in Electronic Design Automation     Full-text available via subscription  
Foundations of Science     Hybrid Journal  
Frontiers in Aerospace Engineering     Open Access   (Followers: 9)
Frontiers in Energy     Hybrid Journal   (Followers: 3)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 2)
Frontiers of Environmental Science & Engineering     Hybrid Journal   (Followers: 4)
Frontiers of Nanoscience     Full-text available via subscription   (Followers: 1)
Fuel and Energy Abstracts     Full-text available via subscription   (Followers: 4)
Fuel Cells     Hybrid Journal   (Followers: 3)
Fuel Cells Bulletin     Full-text available via subscription   (Followers: 4)
Fusion Engineering and Design     Hybrid Journal   (Followers: 9)
Fuzzy Information and Engineering     Open Access   (Followers: 3)
Fuzzy Sets and Systems     Hybrid Journal   (Followers: 4)
Georisk: Assessment and Management of Risk for Engineered Systems and Geohazards     Hybrid Journal   (Followers: 8)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 61)
Geotechnical Testing Journal     Full-text available via subscription   (Followers: 9)
Géotechnique     Hybrid Journal   (Followers: 12)
Geothermics     Hybrid Journal   (Followers: 5)
Glass Technology - European Journal of Glass Science and Technology Part A     Full-text available via subscription   (Followers: 3)
Global Journal of Engineering Research     Full-text available via subscription  
Global Perspective on Engineering Management     Open Access   (Followers: 2)
GPS Solutions     Hybrid Journal   (Followers: 17)
Graphs and Combinatorics     Hybrid Journal   (Followers: 6)
Grass and Forage Science     Hybrid Journal   (Followers: 6)
Great Circle: Journal of the Australian Association for Maritime History, The     Full-text available via subscription   (Followers: 8)
Groundwater for Sustainable Development     Full-text available via subscription  
Handai Nanophotonics     Full-text available via subscription  
Handbook of Adhesives and Sealants     Full-text available via subscription   (Followers: 1)
Handbook of Sensors and Actuators     Full-text available via subscription   (Followers: 8)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Heat Exchangers     Open Access   (Followers: 1)
Heat Transfer - Asian Research     Hybrid Journal   (Followers: 9)
Heat Transfer Engineering     Hybrid Journal   (Followers: 24)
Historical Records of Australian Science     Hybrid Journal   (Followers: 2)
Human Factors in Ergonomics & Manufacturing     Hybrid Journal   (Followers: 5)
IBM Journal of Research and Development     Hybrid Journal   (Followers: 17)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 44)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 36)
IEEE Communications Magazine     Full-text available via subscription   (Followers: 64)
IEEE Control Systems Magazine     Full-text available via subscription   (Followers: 64)
IEEE Engineering Management Review     Full-text available via subscription   (Followers: 33)
IEEE Geoscience and Remote Sensing Letters     Hybrid Journal   (Followers: 59)
IEEE Industry Applications Magazine     Full-text available via subscription   (Followers: 17)
IEEE Instrumentation & Measurement Magazine     Full-text available via subscription   (Followers: 56)
IEEE Journal of Biomedical and Health Informatics     Hybrid Journal   (Followers: 12)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 11)
IEEE Journal of Selected Topics in Quantum Electronics     Hybrid Journal   (Followers: 9)
IEEE Journal of Selected Topics in Signal Processing     Hybrid Journal   (Followers: 26)
IEEE Journal of Solid-State Circuits     Full-text available via subscription   (Followers: 20)
IEEE Journal on Selected Areas in Communications     Hybrid Journal   (Followers: 16)
IEEE Latin America Transactions     Full-text available via subscription   (Followers: 2)
IEEE Microwave and Wireless Components Letters     Hybrid Journal   (Followers: 16)
IEEE Microwave Magazine     Full-text available via subscription   (Followers: 28)
IEEE Potentials     Full-text available via subscription   (Followers: 18)
IEEE Signal Processing Letters     Hybrid Journal   (Followers: 33)
IEEE Spectrum     Full-text available via subscription   (Followers: 130)
IEEE Technology and Society Magazine     Full-text available via subscription   (Followers: 5)
IEEE Transactions on Advanced Packaging     Full-text available via subscription   (Followers: 7)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 35)
IEEE Transactions on Applied Superconductivity     Hybrid Journal   (Followers: 4)
IEEE Transactions on Automation Science and Engineering     Full-text available via subscription   (Followers: 12)
IEEE Transactions on Circuits and Systems II: Express Briefs     Hybrid Journal   (Followers: 15)
IEEE Transactions on Components and Packaging Technologies     Full-text available via subscription   (Followers: 15)
IEEE Transactions on Control Systems Technology     Hybrid Journal   (Followers: 43)
IEEE Transactions on Education     Hybrid Journal   (Followers: 7)
IEEE Transactions on Electronics Packaging Manufacturing     Full-text available via subscription   (Followers: 19)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 11)
IEEE Transactions on Engineering Management     Hybrid Journal   (Followers: 25)
IEEE Transactions on Evolutionary Computation     Hybrid Journal   (Followers: 9)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 17)
IEEE Transactions on Instrumentation and Measurement     Hybrid Journal   (Followers: 48)
IEEE Transactions on Intelligent Transportation Systems     Hybrid Journal   (Followers: 6)
IEEE Transactions on Knowledge and Data Engineering     Hybrid Journal   (Followers: 29)
IEEE Transactions on Magnetics     Hybrid Journal   (Followers: 11)
IEEE Transactions on Microwave Theory and Techniques     Hybrid Journal   (Followers: 24)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 8)
IEEE Transactions on Plasma Science     Hybrid Journal   (Followers: 7)
IEEE Transactions on Power Delivery     Hybrid Journal   (Followers: 17)
IEEE Transactions on Professional Communication     Hybrid Journal   (Followers: 5)
IEEE Transactions on Reliability     Hybrid Journal   (Followers: 31)
IEEE Transactions on Semiconductor Manufacturing     Hybrid Journal   (Followers: 6)
IEEE Transactions on Signal Processing     Hybrid Journal   (Followers: 59)
IEEE Transactions on Vehicular Technology     Hybrid Journal   (Followers: 2)
IEEE Vehicular Technology Magazine     Full-text available via subscription   (Followers: 8)
IEEE/ACM Transactions on Computational Biology and Bioinformatics     Hybrid Journal   (Followers: 15)
IERI Procedia     Open Access  
IET Circuits, Devices & Systems     Hybrid Journal   (Followers: 18)
IET Generation, Transmission & Distribution     Hybrid Journal   (Followers: 2)
IET Image Processing     Hybrid Journal   (Followers: 13)
IET Micro and Nano Letters     Hybrid Journal   (Followers: 6)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 12)

  First | 1 2 3 4 5 6 | Last

Journal Cover AIChE Journal
  [SJR: 1.122]   [H-I: 120]   [28 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  [1609 journals]
  • Three‐Dimensional Modelling of Porosity Development during the
           Gasification of a Char Particle
    • Authors: Kay Wittig; Petr Nikrityuk, Sebastian Schulze, Andreas Richter
      Abstract: This work is devoted to the three‐dimensional, direct modelling of porosity and specific surface development during the gasification of a char particle. The model was developed for heterogeneous reactions occurring inside a char particle in a kinetically controlled regime. The main goal of this work is to analyse the impact of different pore size distributions on the particle carbon conversion rate. In particular, it is shown that under certain conditions the outer particle surface can influence the specific surface area. In this context the possible adaptation of the parameter ψ from the random pore model developed by Bhatia and Perlmutter (AIChE J 26, p. 379–386, 1980) is explained. The results of simulations are compared against the random pore model and discussed. Additionally, based on the results of simulations, the physics behind several input parameters used by the random pore model are explored. Finally, the possible fragmentation of a chemically reacting char particle during its gasification in dependence of instantaneous porosity was investigated numerically. It was shown that the earliest fragmentation occurs at a carbon conversion of about 0.5 to 0.6 due to the disaggregation of the pore walls. The results are discussed and compared implicitly with data published in the literature. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-27T17:41:22.910987-05:
      DOI: 10.1002/aic.15526
       
  • Absorption of Picoliter Droplets by Thin Porous Substrates
    • Authors: Hua Tan
      Abstract: Absorption of picoliter (pL) droplets into porous substrates is studied experimentally and numerically. In the case of pL droplets, major phenomena involved in the interaction between droplet and porous media develop at different time scales: spreading and wetting at microseconds, absorption and wicking at milliseconds, and evaporation at seconds. Therefore, one can decouple these processes to minimize the complexity of the study. A high‐speed imaging system capable of 1 million frames per second is used to visualize individual droplets impacting, spreading, and imbibing on substrates. To simulate droplet dynamics, the governing equations for flow outside and inside porous media are proposed and solved using an in‐house developed computational fluid dynamics (CFD) solver. The simulation results are in good agreement with the experimental data. The effect of drop impact velocity and fluid properties on final dot shape in the porous substrates is investigated through a series of parametric numerical studies. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-27T17:41:06.274527-05:
      DOI: 10.1002/aic.15525
       
  • Hydrocarbon Steam Reforming Using Silicalite‐1 Zeolite Encapsulated
           Ni‐Based Catalyst
    • Authors: Ummuhan Cimenler; Babu Joseph, John N. Kuhn
      Abstract: A Silicalite‐1 zeolite membrane encapsulated 1.6wt%Ni‐1.2wt%Mg/Ce0.6Zr0.4O2 steam reforming composite catalyst synthesized by a physical coating method was used to investigate effect of encapsulation on size selective steam reforming, using methane (CH4) and toluene (C7H8) as representative species. Characterization methods (Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), Physisorption Analysis, and X‐ray Diffraction (XRD)) were used to analyze pre‐ and post‐reaction samples. SEM, EDS and XRD analyses showed that Silicalite‐1 was coated successfully onto the core catalyst. Weisz‐Prater Criteria and Thiele moduli calculations indicated internal diffusion limitations. Combined reforming of CH4 and C7H8 at 800°C on the composite catalyst demonstrated stability during the 10 h time on stream while the uncoated SR catalyst deactivated. The non‐acidic Silicalite‐1 encapsulated catalyst showed decreases (∼2‐7%) in both CH4 and C7H8 conversions compared to acidic H‐β zeolite confirming that shell acidity did contribute to conversion and suggested that shell defects/grain boundaries were responsible for the C7H8 conversion. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T18:11:10.178664-05:
      DOI: 10.1002/aic.15521
       
  • Large‐Scale Heat Exchanger Networks Synthesis using Simulated Annealing
           and the novel Rocket Fireworks Optimization
    • Abstract: Heat Exchanger Network (HEN) synthesis is an important field of study in process engineering. However, obtaining optimal HEN design is a complex task. When mathematically formulated, it may require sophisticated methods to achieve good solutions. The complexity increases even more for large‐scale HEN. In this work, a hybrid meta‐heuristic method is presented. A rather simple Simulated Annealing approach is used for the combinatorial level, while a strategy named Rocket Fireworks Optimization is developed and applied to the continuous domain. An advantage over other approaches is that the algorithm was written in C++, which is free and faster when compared to many other languages. The developed method was able to provide the lowest costs solutions reported so far to six cases well studied in the literature. An important feature of the approach here proposed is that, differently from other approaches, it does not split HEN into smaller problems during the optimization. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T18:11:06.773893-05:
      DOI: 10.1002/aic.15524
       
  • Pinch‐based Shortcut Method for the Conceptual Design of Isothermal
           Extraction Columns
    • Authors: Christian Redepenning; Sebastian Recker, Wolfgang Marquardt
      Abstract: Shortcut methods are valuable tools for a comprehensive evaluation of key performance indicators in the early phase of conceptual process design. For the design of extraction columns, operation at minimum solvent demand represents a thermodynamically sound indicator, which is, however, difficult to determine. The suggested shortcut model therefore exploits the existence of the pinch point to directly identify operation at minimum solvent demand. It is solved quickly and reliably by a step‐by‐step procedure. The final step allows a reduction of the approximation error to any desired degree of accuracy. No simplifications regarding the number of components in the mixture or its thermodynamic behavior are introduced. Hence, arbitrary mixtures can be tackled. The performance of the method is highlighted by a fully automated screening of thousands of solvents for the recovery of fermentation products acetone, 1‐butanol, and ethanol from aqueous solution. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T18:06:29.156423-05:
      DOI: 10.1002/aic.15523
       
  • A Packed‐Bed Solar Reactor for the Carbothermal Zinc Production –
           Dynamic Modelling and Experimental Validation
    • Authors: N. Tzouganatos; C. Wieckert, A. Steinfeld
      Abstract: Integration of concentrated solar energy into the pyrometallurgical Zn production process as clean source of high‐temperature process heat could significantly reduce fossil fuels consumption and its concomitant CO2 emissions. The solar‐driven carbothermal reduction of ZnO is investigated using a 10‐kWth solar reactor featuring two cavities, the upper one serving as the solar absorber and the lower one containing a packed‐bed of ZnO and beech charcoal as the biogenic reducing agent. Experimentation in a high‐flux solar simulator is carried out under radiative fluxes of 2300 – 2890 suns, yielding a peak solar‐to‐chemical energy conversion efficiency of 18.4%. The reactor performance under variable operating conditions is analysed via a dynamic numerical model coupling heat transfer with chemical kinetics. The model is validated by comparison to the experimental data obtained with the 10‐kWth packed‐bed solar reactor and further applied to predict the effect of incorporating semi‐continuous feeding of reactants on the process efficiency. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T18:06:22.845143-05:
      DOI: 10.1002/aic.15522
       
  • Investigating dry reforming of methane with spatial reactor profiles and
           particle‐resolved CFD simulations†
    • Abstract: Dry reforming of methane (DRM) over nickel in a fixed‐bed reactor of spheres was studied experimentally and with CFD simulations. Temperature and mole fraction profiles were measured in a dedicated profile reactor as function of axial coordinate. Particle‐resolved CFD simulations took into account conjugate heat transfer, surface‐to‐surface radiation, and surface reactions described by microkinetics. Energy transport of CFD simulations were verified by studying heat transfer without chemical reactions. DRM experiments could not be reproduced with the original microkinetics formulation, even with the axial temperature profile applied. A detailed analysis of the microkinetics showed that thermodynamic inconsistencies are present, which are amplified by high surface coverage of CO*. After modifying the mechanism the experiments could be reproduced. This study shows how complex interactions between local transport phenomena and local kinetics can be quantified without relying on transport correlations. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T10:15:28.585484-05:
      DOI: 10.1002/aic.15520
       
  • Mechanistic Insights into Aqueous Phase Propanol Dehydration in
           H‐ZSM‐5 Zeolite
    • Authors: Donghai Mei; Johannes A. Lercher
      Abstract: Aqueous phase dehydration of 1‐propanol over H‐ZSM‐5 zeolite was investigated using density functional theory (DFT) calculations. The water molecules in the zeolite pores prefer to aggregate via the hydrogen bonding network and be protonated at the Brønsted acidic sites (BAS). Two typical configurations, i.e., dispersed and clustered, of water molecules were identified by ab initio molecular dynamics simulations of the mimicking aqueous phase H‐ZSM‐5 unit cell with 20 water molecules per unit cell. DFT calculated Gibbs free energies suggest that the dimeric propanol‐propanol, the propanol‐water, and the trimeric propanol‐propanol‐water complexes are formed at high propanol concentrations in aqueous phase, which provide a kinetically feasible dehydration reaction channel of 1‐propanol to propene. The calculation results indicate that the propanol dehydration via the unimolecular mechanism becomes kinetically discouraged due to the enhanced stability of the protonated dimeric propanol and the protonated water cluster acting as the BAS site for alcohol dehydration. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T10:15:23.019629-05:
      DOI: 10.1002/aic.15517
       
  • Performance of Combined Use of Chlorosilanes and AlCl3 in the
           Carboxylation of Toluene with CO2
    • Authors: Xibao Zhang; Zhenmin Cheng
      Abstract: Carboxylation of toluene with CO2 for the production of p‐toluic acid was shown to be promoted by the addition of Me2PhSiCl, Ph2SiCl2, Ph3SiH or Ph3SiCl into the AlCl3 activated system, and the reaction activity was in the increasing order of Ph2SiCl2 
      PubDate: 2016-09-26T10:15:20.572432-05:
      DOI: 10.1002/aic.15519
       
  • Enhancing co‐production of H2 and syngas via water splitting and POM on
           surface‐modified oxygen permeable membranes1
    • Abstract: In this paper, we report a detailed study on co‐production of H2 and syngas on La0.9Ca0.1FeO3‐δ (LCF‐91) membranes via water splitting and partial oxidation of methane (POM), respectively. A permeation model shows that the surface reaction on the sweep side is the rate limiting step for this process on a 0.9 mm‐thick dense membrane at 990oC. Hence, sweep side surface modifications such as adding a porous layer and nickel catalysts were applied; the hydrogen production rate from water thermolysis is enhanced by two orders of magnitude to 0.37 μmol/cm2•s compared with the results on the unmodified membrane. At the sweep side exit, syngas (H2/CO = 2) is produced and negligible solid carbon is found. Yet near the membrane surface on the sweep side, methane can decompose into solid carbon and hydrogen at the surface, or it may be oxidized into CO and CO2, depending on the oxygen permeation flux. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T10:10:23.467095-05:
      DOI: 10.1002/aic.15518
       
  • A New and original microwave continuous reactor under high pressure for
           future chemistry
    • Authors: I. Polaert; L. Estel, D. Luart, C. Len, M. Delmotte
      Abstract: A new and original high pressure reactor has been designed and developed for continuous flow chemistry under microwaves at industrial scale. The reactor originality is that the microwave applicator is the reactor itself. It allows then the use of metallic and thick walls for the reactor adapted to a use at high pressures and high temperatures. Wave propagation coupled to heat transfer was simulated using COMSOL Multiphysics® and the design was optimized in order to minimize wave reflections and maximize energy transfers in the reacting medium. This leads to extremely good energy yields. Experiments confirm that the microwave energy is fully absorbed by the reacting medium. The reactor allows continuous chemical reactions at a kg/h scale, under microwave heating, up to 7 MPa and 200°C. The double dehydration of hexylene glycol has been performed under various operating conditions demonstrating then the operability of this new reactor. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-26T04:00:43.30936-05:0
      DOI: 10.1002/aic.15515
       
  • Mechanism of the effects of microwave irradiation on the relative
           volatility of binary mixtures
    • Authors: Hong Li; Junjie Cui, Jiahui Liu, Xingang Li, Xin Gao
      Abstract: The use of microwave irradiation to enhance distillation processes has been reported recently. However, there is an ongoing debate in the scientific community on whether the observed enhancement is mainly a consequence of the shift of the “equilibrium” of vapor‐liquid mass transfer. In this paper, a developed instrument was used to determine the relative volatility of various binary mixtures under microwave irradiation. By comparing the relative volatility in the presence/absence of microwave irradiation, the shift of the “equilibrium” of vapor‐liquid mass transfer was observed for certain binary mixtures under microwave irradiation. The effects of microwave irradiation on the relative volatility of binary mixtures (in addition to the mechanisms involved therein) were analyzed using the non‐equilibrium thermodynamic principle. The results demonstrate that differences in the dielectric properties, microwave field intensity, intermolecular forces, and boiling point play dominant roles in determining the effects of microwaves on the relative volatility. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T18:15:27.600831-05:
      DOI: 10.1002/aic.15513
       
  • Particle Entrainment from Gas‐Solid Fluidized Beds: Conductive vs.
           Dielectric Fines
    • Authors: Farzam Fotovat; John R. Grace, Xiaotao T. Bi
      Abstract: Conductive and non‐conductive fine powders were entrained by air at atmospheric temperature and pressure in a fluidization column of diameter 0.15 m made of stainless steel. Under equivalent operating conditions, entrainment of the conductive particles was markedly higher than for non‐conductive species. This finding cannot be explained by hydrodynamic factors. Examining the electrostatic interaction between touching particles reveals that dominance of the inter‐particle attractive forces hinders independent motion of non‐conductive particles in the freeboard. In addition, because of non‐uniform distribution of the electrical charges over the surface of dielectric particles, they are subject to stronger electrostatic forces than for particles made of conductive materials. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T18:15:23.344629-05:
      DOI: 10.1002/aic.15514
       
  • Mathematical modelling and experimental validation of a novel periodic
           flow crystallization using MSMPR crystallizers
    • Authors: Qinglin Su; Keddon A. Powell, Chris D. Rielly, Zoltan K. Nagy
      Abstract: The challenges of insufficient residence time for crystal growing and transfer line blockage in conventional continuous MSMPR operations are still not well addressed. Periodic flow crystallization is a novel method whereby controlled periodic disruptions are applied to the inlet and outlet flows of an MSMPR crystallizer in order to increase its residence time. A dynamic model of residence time distribution in an MSMPR crystallizer was first developed to demonstrate the periodic flow operation. Besides, process models of periodic flow crystallizations were developed with an aim to provide a better understanding and improve the performance of the periodic flow operation, wherein the crystallization mechanisms and kinetics of the glycine‐water system were estimated from batch cooling crystallization experiments. Experiments of periodic flow crystallizations were also conducted in single‐/three‐stage MSMPR crystallizers to validate the process models and demonstrate the advantages of using periodic flow operation in MSMPR stages. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:25:22.155663-05:
      DOI: 10.1002/aic.15510
       
  • Preparation of Thin Film Nanocomposite Membranes with Surface Modified MOF
           for High Flux Organic Solvent Nanofiltration
    • Authors: Xiangyu Guo; Dahuan Liu, Tongtong Han, Hongliang Huang, Qingyuan Yang, Chongli Zhong
      Abstract: Preparation of defect‐free and optimized thin film nanocomposite (TFN) membranes is an effective way to enhance the process of organic solvent nanofiltration. However, it still remains a great challenge due to poor filler particle dispersibility in organic phase and compatible issue between fillers and polymers. Aiming at these difficulties, UiO‐66‐NH2 nanoparticles were surface modified with long alkyl chains and used in the preparation of TFN membranes. As a result, defect‐free TFN membranes with ultrathin MOF@polyamide layer were successfully prepared benefited from the improved particle dispersibility in n‐hexane. Significant enhancement was found in methanol permeance after nanoparticle incorporation, without comprising the tetracycline rejection evidently. Especially, the novel TFN membrane prepared with organic phase solution containing 0.15% (w/v) modified UiO‐66‐NH2 nanoparticles showed a superior methanol permeance of 20 L·m−2·h−1·bar−1 and a tetracycline rejection of about 99%, which is appealing to the application in pharmaceutical industry for example. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:10:40.923949-05:
      DOI: 10.1002/aic.15508
       
  • Water Content of Light n‐Alkanes: New Measurements and
           Cubic‐Plus‐Association Equation of State Modelling
    • Authors: Mohsen Zirrahi; Hassan Hassanzadeh, Jalal Abedi
      Abstract: Light hydrocarbon gases such as methane, ethane, propane, and butane or other so called gaseous solvents have been suggested as steam additives to improve bitumen recovery and energy efficiency. The water content of these gases is one of the key requirements in the simulation and design of solvent‐aided thermal heavy oil recovery processes. In this work, we present new experimental data for the water content of these gases at high temperatures (up to 493.15 K) and moderate pressures (P 
      PubDate: 2016-09-22T10:10:36.194183-05:
      DOI: 10.1002/aic.15512
       
  • Input‐output Pairing Accounting for Both Structure and Strength in
           Coupling
    • Authors: Xunyuan Yin; Jinfeng Liua
      Abstract: Input‐output pairing is an important problem in control system design and is often performed using the relative gain array (RGA) based approaches. While RGA‐based approaches have been very successful in many applications, they have some well‐known limitations. For example, they may give results which are not consistent with the physical topology since only the strength of interaction between inputs and outputs is taken into account in the RGA. In this work, we propose a new measure for input‐output pairing that explores both strength and structural information in input‐output coupling. Specifically, we take advantage of the tool of relative degree to measure the physical closeness of input‐output pairs and to explore the strength of interaction progressively with respect to the relative degree. We call the proposed measure relative sensitivity array (RSA) between inputs and outputs. Detailed analysis is performed to reveal the relationship between the gain matrix used in the RGA and the sensitivity matrix in the RSA from a mathematical point of view. Since the RSA is an analog of the RGA, many existing pairing guidelines developed for the RGA can be used in the proposed RSA‐based pairing. The proposed RSA‐based approach is applied to two examples. The results show that pairs formed by the proposed approach are consistent with the physical topologies of the processes. Also, the results show that the proposed approach can handle larger systems that cannot be effectively handled by RGA‐based approaches. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:05:28.847603-05:
      DOI: 10.1002/aic.15511
       
  • An approach for drag correction based on the local heterogeneity for
           gas‐solid flows
    • Authors: Tingwen Li; Limin Wang, William Rogers, Guofeng Zhou, Wei Ge
      Abstract: The drag models typically used for gas‐solids interaction are mainly developed based on homogeneous systems of flow passing fixed particle assembly. It has been shown that the heterogeneous structures, i.e. clusters and bubbles in fluidized beds, need to be resolved to account for their effect in the numerical simulations. Since the heterogeneity is essentially captured through the local concentration gradient in the computational cells, the present study proposes a simple approach to account for the non‐uniformity of solids spatial distribution inside a computational cell and its effect on the interaction between gas and solid phases. To validate this approach, the predicted drag coefficient has been compared to the results from direct numerical simulations. In addition, the need to account for this type of heterogeneity is discussed for a periodic riser flow simulation with highly resolved numerical grids and the impact of the proposed correction for drag is demonstrated. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:05:27.756508-05:
      DOI: 10.1002/aic.15507
       
  • Thermodynamic equilibrium solutions through a modified Newton Raphson
           method
    • Authors: M. Marinoni; J. Carrayrou, Y. Lucas, P. Ackerer
      Abstract: In numerical codes for reactive transport modeling, systems of nonlinear chemical equations are often solved through the Newton Raphson method (NR). NR is an iterative procedure that results in a sequential solution of linear systems. The algorithm is known for its effectiveness in the vicinity of the solution but also for its lack of robustness otherwise. Therefore, inaccurate initial conditions can lead to non‐convergence or excessive numbers of iterations, which significantly increase the computational cost. In this work, we show that inaccurate initial conditions can lead to very ill‐conditioned system matrices, which makes NR inefficient. This efficiency is improved by preconditioning techniques and/or by coupling the NR method with a zero‐order method called the Positive Continuous Fraction (PCF) method. Numerical experiments that are based on 7 different test cases show that the ill‐conditioned linear systems within NR represent a problem and that coupling NR with a method that bypasses the computation of the Jacobian matrix significantly improves the robustness and efficiency of the algorithm. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:05:25.590484-05:
      DOI: 10.1002/aic.15506
       
  • Controlling three dimensional ice template via two dimensional surface
           wetting
    • Abstract: Directional freezing is a fast, scalable, and environmental friendly technique for fabricating monoliths with long‐range oriented pores, which can be applied towards a wide variety of materials. However, the pore size is typically larger than 20 μm and cannot be spatially controlled, which prevent the technique from being used more widely. In this work, effect of wettability of the freezing substrate on the pore size of monolithic PEG cryogels is studied. Smaller pores can be generated via more hydrophilic substrates, and tubular pores smaller 5 μm can be created using a poly(vinyl alcohol) coated copper substrate. A numerical fitting between water contact angle of the substrates and pore size is then obtained. Moreover, pore size can be locally varied duplicating wetting patterns of the substrates. The concept of using two dimensional patterns to build monoliths with three dimensional microstructures can probably be extended to other material systems. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-22T10:05:23.386955-05:
      DOI: 10.1002/aic.15509
       
  • Optimization of Large‐Scale Water Transfer Networks: Conic Integer
           Programming Model and Distributed Parallel Algorithms
    • Abstract: We address in this paper the optimization of a multi‐echelon water transfer network and the associate transportation and inventory systems with demand uncertainty. Optimal network structure, facility locations, operation capacities, as well as the inventory and transportation decisions can be simultaneously determined by the MINLP model which includes bilinear, square root and nonlinear fractional terms. By exploiting the properties of this model, we reformulate the MINLP problem as a conic integer optimization model. To overcome the memory and computing bandwidth limitations caused by the huge number of active nodes in the branch‐and‐bound search tree, novel distributed parallel optimization algorithms based on Lagrangean relaxation and message passing interface as well as their serial versions are proposed to solve the resulting conic integer programming model. A regional water transfer network in China is studied to demonstrate the applicability of the proposed model and the performance of the algorithms. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-20T18:35:27.357044-05:
      DOI: 10.1002/aic.15505
       
  • Simultaneous Removal of NO and SO2 Using Aqueous Peroxymonosulfate with
           Coactivation of Cu2+/Fe3+ and High Temperature
    • Authors: Yangxian Liu; Yan Wang
      Abstract: A novel process on simultaneous removal of NO and SO2 using aqueous peroxymonosulfate (PMS) with synergic activation of Cu2+/Fe3+ and high temperature in an impinging stream reactor is developed for the first time. Effects of PMS concentration, Cu2+/Fe3+ concentration, reaction temperature, solution pH, flue gas flow, liquid‐gas ratio, gas components and inorganic ions on NO/SO2 removals were investigated. Active species and products were determined by electron spin resonance spectroscopy and ion chromatography. Removal pathways of NO/SO2 were revealed, and mass transfer‐reaction kinetics of NO removal was studied. The optimal experimental conditions are obtained. H2SO4 and HNO3 are the main products. It is found that there is a clear synergy between Cu2+/Fe3+ and high temperature for activating PMS. SO4·‐ and ·OH are found to be the main oxidants for NO removal. NO removals belong to pseudo‐first fast reactions in the two investigated oxidation systems. Besides, the kinetic parameters are also measured. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-16T18:05:58.57713-05:0
      DOI: 10.1002/aic.15503
       
  • Spatial and Temporal Scaling of Unequal Microbubble Coalescence
    • Authors: Rou Chen; Huidan Whitney Yu, Likun Zhu, Taehun Lee, Raveena M. Patil
      Abstract: We numerically study coalescence of air microbubbles in water, with density ratio 833 and viscosity ratio 50.5, using lattice Boltzmann method. The focus is on the effects of size inequality of parent bubbles on the interfacial dynamics and coalescence time. Twelve cases, varying the size ratio of large to small parent bubble from 5.33 to 1, are systematically investigated. The “coalescence preference”, coalesced bubble closer to the larger parent bubble, is well observed and the captured power‐law relation between the preferential relative distance χ and size inequality γ, χ ∼ γ−2.079, is consistent to the recent experimental observations. Meanwhile, the coalescence time also exhibits power‐law scaling as T ∼ γ−0.7, indicating that unequal bubbles coalesce faster than equal bubbles. Such a temporal scaling of coalescence on size inequality is believed to be the first‐time observation as the fast coalescence of microbubbles is generally hard to be recorded through laboratory experimentation. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-16T18:05:54.018584-05:
      DOI: 10.1002/aic.15504
       
  • High‐rate hydrogen separation using an MIEC oxygen permeable
           membrane reactor
    • Authors: Wenping Li; Zhongwei Cao, Xuefeng Zhu, Weishen Yang
      Abstract: In this study, we propose using mixed ionic‐electronic conducting (MIEC) oxygen permeable membrane to separate hydrogen via the water splitting reaction. To do that, steam was fed to one side of the membrane (side I) and a low‐purity hydrogen was fed to the other side (side II). Oxygen from water splitting on side I permeates through the membrane driven by an oxygen chemical potential gradient across the membrane to react with the low‐purity hydrogen on side II. After condensation and drying, high‐purity hydrogen is acquired from side I. Thus, the hydrogen separation process is realized based on the fact that the low‐purity hydrogen is consumed and high‐purity hydrogen is acquired. We achieved a high hydrogen separation rate (13.5 mL cm−2 min−1) at 950°C in a reactor equipped with a 0.5‐mm‐thick Ba0.98Ce0.05Fe0.95O3‐δ membrane. This research proofed that it is feasible to upgrade hydrogen purity using an MIEC oxygen permeable membrane. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-12T04:15:23.29002-05:0
      DOI: 10.1002/aic.15502
       
  • Splitting CO2 with a ceria‐based redox cycle in a solar‐driven
           thermogravimetric analyzer
    • Abstract: Thermochemical splitting of CO2 via a ceria‐based redox cycle was performed in a solar‐driven thermogravimetric analyzer. Overall reaction rates, including heat and mass transport, were determined under concentrated irradiation mimicking realistic operation of solar reactors. Reticulated porous ceramic (RPC) structures and fibers made of undoped and Zr4+‐doped CeO2, were endothermally reduced under radiative fluxes of 1280 suns in the temperature range 1200‐1950 K and subsequently re‐oxidized with CO2 at 950‐1400 K. Rapid and uniform heating was observed for 8 ppi ceria RPC with mm‐sized porosity due to its low optical thickness and volumetric radiative absorption, while ceria fibers with μm‐sized porosity performed poorly due to its opacity to incident irradiation. The 10 ppi RPC exhibited higher fuel yield because of its higher sample density. Zr4+‐doped ceria showed increasing reduction extents with dopant concentration but decreasing specific CO yield due to unfavorable oxidation thermodynamics and slower kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-12T03:35:31.982987-05:
      DOI: 10.1002/aic.15501
       
  • Pinch‐based Shortcut Method for the Conceptual Design of Adiabatic
           Absorption Columns
    • Authors: Christian Redepenning; Wolfgang Marquardt
      Abstract: Shortcut methods are valuable tools for the fast evaluation of key performance indicators in the early phase of conceptual process design. For the design of absorption columns, operation at minimum solvent demand represents a thermodynamically sound indicator, which is, however, difficult to determine because an infinite number of separation stages need to be considered. Instead, the suggested shortcut model exploits the existence of the pinch point to identify operation at minimum solvent demand. Existing shortcut concepts, such as the well‐known equation of Kremser\,(1930), are significantly outperformed by the novel shortcut model, which can be gradually refined to any desired accuracy. Integration into a stepwise procedure results in reliable solutions. The model covers rigorous thermodynamics; no simplifications regarding phase equilibrium, heat effects, or number of components are required. The performance of the method is illustrated by several case studies with up to seven components. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-08T03:50:19.959463-05:
      DOI: 10.1002/aic.15499
       
  • Pinched Tube Flow Reactor: Hydrodynamics and Suitability for Exothermic
           Multiphase Reactions
    • Authors: Mrityunjay K. Sharma; Shital B. Potdar, Amol A. Kulkarni
      Abstract: A novel tubular flow reactor where a straight tube is modified by pinching it periodically at a fixed pitch and at different angles is presented. Pinched tubes (straight tube as well as helical coils) with different pitch and angles between successive pinching are studied. This work reports a detailed hydrodynamic study involving single and two phase flow. Mixing experiments showed that having an angle of 90° between successive pinchs achieves the shortest mixing length when compared to lower angles. Pressure recovery along with sequence of high and low shear zones and change of flow direction imposed better mixing. RTD studies showed that higher number of pinch sections decreases the extent of dispersion, yet it deviates from plug flow. The performance is evaluated by carrying a homogeneous and two‐phase aromatic nitration and also liquid‐liquid extraction. Pinched tube presents an economical option as a flow reactor for conducting exothermic reactions. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-07T18:45:43.619172-05:
      DOI: 10.1002/aic.15498
       
  • Highly stable hydrophobic SiNCO nanoparticle‐modified silicon nitride
           membrane for zero‐discharge water desalination
    • Abstract: Membrane distillation water desalination can attain a significantly higher water recovery than reverse osmosis, while the lack of stable hydrophobic membranes limits its commercial applications. This paper presents the preparation of a new hydrophobic membrane by modifying a porous Si3N4 substrate with vesicular SiNCO nano‐particles. The membrane had a water contact angle of 142°, due to the presence of ‐Si‐CH3 terminal groups and the high surface roughness. The contact angle remained nearly the same after exposures of the membrane to boiling water, aqueous solutions with pH ranging from 2 to 12, and benzene. The membrane exhibited satisfactory water desalination performance on highly concentrated NaCl solutions and simulated seawater. With the highly stable membrane, it is promising to develop a zero‐discharge water desalination process for simultaneous production of fresh water for daily uses and brine for industrial uses. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-07T18:45:29.116822-05:
      DOI: 10.1002/aic.15500
       
  • Kinetics of Homogeneous 5‐Hydroxymethylfurfural Oxidation to
           2,5‐Furandicarboxylic Acid with Co/Mn/Br Catalyst
    • Authors: Xiaobin Zuo; Amit S. Chaudhari, Kirk Snavely, Fenghui Niu, Hongda Zhu, Kevin J. Martin, Bala Subramaniam
      Abstract: 2,5‐furandicarboxylic acid (FDCA) is a potential non‐phthalate based bio‐renewable substitute for terephthalic acid (TPA)‐based plastics. Herein, we present an investigation of the oxidation rate of 5‐hydroxymethylfurfural (HMF) to FDCA in acetic acid medium using Co/Mn/Br catalyst. Transient concentration profiles of the reactant (HMF), intermediates [2,5‐diformylfuran (DFF), 5‐formyl‐2‐furancarboxylic acid (FFCA)] and the final product (FDCA) were obtained for this relatively fast reaction in a stirred semi‐batch reactor using rapid in‐line sampling. Comparison of the effective rate constants for the series oxidation steps with predicted gas‐liquid mass transfer coefficients reveal that except for the FFCA → FDCA step, the first two oxidation steps are subject to gas‐liquid mass transfer limitations even at high stirrer speeds. Novel reactor configurations, such as a reactor in which the reaction mixture is dispersed as fine droplets into a gas phase containing oxygen are required to overcome oxygen starvation in the liquid phase and further intensify FDCA production. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-04T22:05:30.502232-05:
      DOI: 10.1002/aic.15497
       
  • Mixing and residence time distribution in ultrasonic microreactors
    • Authors: Zhengya Dong; Shuainan Zhao, Yuchao Zhang, Chaoqun Yao, Guangwen Chen, Quan Yuan
      Abstract: Intensification of liquid mixing was investigated in domestic fabricated ultrasonic microreactors. Under the ultrasonic field, cavitation bubbles were generated, which undergo vigorous translational motion and surface oscillation with different modes (volume, shape oscillation and transient collapse). These cavitation phenomena induce intensive convective mixing and reduce the mixing time from 24‐32 s to 0.2‐1.0 s. The mixing performance decreases with the channel size, due to the weaker cavitation activity in smaller channel. The energy efficiency is comparable to that of the conventional T‐type and higher than the Y‐type and Caterpillar microreactors. Residence time distribution (RTD) was also measured by a stimulus‐response experiment and analyzed with axial dispersion model. Axial dispersion was significantly reduced by the ultrasound‐induced radial mixing, leading to the increasing of Bo number with ultrasound power. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-02T14:05:57.153148-05:
      DOI: 10.1002/aic.15493
       
  • CO2 Methanation: Optimal Start‐Up Control of a Fixed‐Bed Reactor for
           Power‐To‐Gas Applications
    • Abstract: Utilizing volatile renewable energy sources (e.g., solar, wind) for chemical production systems requires a deeper understanding of their dynamic operation modes. Taking the example of a methanation reactor in the context of power‐to‐gas applications, a dynamic optimization approach is used to identify control trajectories for a time optimal reactor start‐up avoiding distinct hot spot formation. For the optimization, we develop a dynamic, two‐dimensional model of a fixed‐bed tube reactor for carbon dioxide methanation which is based on the reaction scheme of the underlying exothermic Sabatier reaction mechanism. While controlling dynamic hot spot formation inside the catalyst bed, we prove the applicability of our methodology and investigate the feasibility of dynamic carbon dioxide methanation. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-02T14:00:25.30614-05:0
      DOI: 10.1002/aic.15496
       
  • Atomically dispersed Pd on nanostructured TiO2 for NO removal by solar
           light
    • Authors: Kakeru Fujiwara; Sotiris E. Pratsinis
      Abstract: Reducing the particle size of noble metals on ceramic supports can maximize noble metal performance and minimize its use. Here Pd clusters onto nanostructured TiO2 particles are prepared in one step by scalable flame aerosol technology while controlling the Pd cluster size from a few nanometers to that of single atoms. Annealing such materials at appropriate temperatures leads to solar photocatalytic NOx removal in a standard ISO reactor up to10 times faster than that of commercial TiO2 (P25, Evonik). Such superior performance can be attained by only 0.1 wt% Pd loading on TiO2. Annealing these flame‐made powders in air up to 600 oC decreases the amorphous TiO2 fraction and increases its crystal and particle sizes as observed by X‐ray diffraction (XRD) and N2 adsorption. The growth of single Pd atoms to Pd clusters on TiO2 prepared at different Pd loading and annealing conditions was investigated by scanning transmission electron microscopy (STEM) and XRD.The single Pd atoms and clusters on TiO2 are stable up to, at least, 600 oC for 2 hours in air but at 800 oC they grow into PdO nanoparticles whose fraction is comparable with the nominal Pd loading. Hence, most of Pd atoms are on the TiO2 surface where at 800 oC they diffuse and coalesce. Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) reveals NO adsorption on single, double, 3‐ and 4‐fold coordinated Pd atoms depending on their synthesis and annealing conditions. The peak intensity of NO adsorption sites involving multiple Pd atoms is substantially lower in TiO2 containing 0.1 wt% than 1 wt% Pd but that intensity from single Pd atoms is comparable. This indicates the dominance of isolated Pd atoms compared to clusters in Pd/TiO2 containing 0.1 wt% Pd that match or exceed the photocatalytic NOx removal of Pd/TiO2 of higher Pd contents. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-02T13:55:25.565223-05:
      DOI: 10.1002/aic.15495
       
  • Liquid‐Phase Axial Dispersion of Turbulent Gas‐Liquid Co‐Current
           Flow through Screen‐type Static Mixers
    • Authors: Fouad Azizi; Khaled Abou Hweij
      Abstract: This paper discusses the characteristics of turbulent gas‐liquid flow through tubular reactors/contactors equipped with screen‐type static mixers from a macromixing perspective. The effect of changing the reactor configuration, and the operating conditions, were investigated by using four different screen geometries of varying mesh numbers.Residence time distribution experiments were conducted in the turbulent regime (4,500 
      PubDate: 2016-09-02T12:45:23.463773-05:
      DOI: 10.1002/aic.15494
       
  • Preparation of open‐cell foams from polymer blends by supercritical CO2
           and their efficient oil‐absorbing performance
    • Abstract: This letter reports on the hydrophobicity and oleophilicity of open‐cell foams from polymer blends prepared by supercritical CO2. A typical bulk density of the foam is measured to be 0.05 g/cm3. The contact angle of the foam with water is determined to be 139.2°. The foam can selectively absorb the diesel from water with the uptake capacity of 17.0 g/g. The foams are technologically promising for application of oil spill cleanup. This article is protected by copyright. All rights reserved.
      PubDate: 2016-09-02T12:35:22.063477-05:
      DOI: 10.1002/aic.15492
       
  • Issue information
    • Abstract: Cover illustration. New materials designed at the atomic level are key to more efficient processes and energy storage and utilization. Courtesy of Harold H. Kung. 10.1002/aic.15386
      PubDate: 2016-09-02T09:30:03.498664-05:
      DOI: 10.1002/aic.14999
       
  • Novel Fe/MnK‐CNTs Nanocomposites as Catalysts for Direct Production of
           Lower Olefins from Syngas
    • Authors: Di Wang; Jian Ji, Bingxu Chen, Wenyao Chen, Gang Qian, Xuezhi Duan, Xinggui Zhou, Di Wang, Anders Holmen, De Chen, John C. Walmsley
      Abstract: Novel Fe/MnK‐CNTs nanocomposites are developed as catalysts for direct production of lower olefins from syngas, delivering a high iron time yield of 337.2 μmolCO·gFe−1·s−1 with 51.3%C selectivity toward C2‐C4 olefins under the optimal reaction conditions (270 oC, 2.0 MPa, 30000 mL·h−1·gcat−1). These catalysts are optimized by varying calcination temperature from 150 to 400 oC. Multiple techniques including TEM, Elemental mapping, XRD, XPS, H2‐TPR and Raman were employed to reveal the relationship between the catalyst nature and unique catalytic behavior. In particular, the resultant catalyst from the calcination temperature of 220 oC exhibits the highest selectivity of C2‐C4 olefins as well as good stability, which are enabled by the trade‐off among the effects of iron particle sizes, promoters, metal‐support interaction and support surface chemistry. Moreover, influences of reaction temperature, reaction pressure and space velocity are also investigated. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-31T18:50:34.976448-05:
      DOI: 10.1002/aic.15490
       
  • Meso‐scale statistical properties of gas‐solid flow a direct numerical
           simulation (DNS) study
    • Authors: Xiaowen Liu; Limin Wang, Wei Ge
      Abstract: Statistical properties of particles in heterogeneous gas‐solid flow were numerically investigated based on the results of a three‐dimensional large‐scale direct numerical simulation (DNS). Strong scale‐dependence and local non‐equilibrium of these properties, especially the particle fluctuating velocity (PFV) or granular temperature, were observed to be related to the effect of meso‐scale structures formed by the compromise in competition between fluid and particle dominated mechanisms. To quantify such effects, the heterogeneous structures were partitioned into a gas‐rich dilute phase and a solid‐rich dense phase according to the particle‐scale voidage defined through the Voronoi tessellation. Non‐equilibrium features, such as the deviation of PFV from Gaussian distribution and anisotropy, were found even in phase‐specific properties. A new distribution function for the PFV well characterizing these features was obtained by fitting the DNS results, which takes a typical bi‐disperse mode, with phase‐specific granular temperatures. The implications of these findings to the kinetic theory of granular flow and traditional continuum models of gas‐solid flow were also discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-31T18:50:25.336157-05:
      DOI: 10.1002/aic.15489
       
  • Kinetics of oxidative cracking of n‐hexane to olefins over
           VOx/Ce‐Al2O3 under gas phase oxygen‐free environment
    • Authors: AbdAlwadood H. Elbadawi; Muhammad Y. Khan, Mohammad R. Quddus, Shaikh A. Razzak, Mohammad M. Hossain
      Abstract: The kinetics of oxidative cracking of n‐hexane to olefins using lattice oxygen of VOx/Ce‐Al2O3 is investigated. The TPR/TPO analysis shows a consistent reducibility (79%) of VOx/Ce‐Al2O3 in repeated redox cycles. The total acidity of the sample is found to be 0.54 mmol/g with 22% are strong acid sites that favors olefin selectivity. The oxidative cracking of n‐hexane in a fluidized CREC Riser simulator gives approximately 60% olefin selectivity at 30% n‐hexane conversion. A kinetic model is developed considering (i) cracking, (ii) ODH and (iii) catalyst deactivations. The proposed cracking mechanism considers adsorption, C‐H and C‐C bond fission and desorption as elementary steps and implemented by pseudo steady state hypothesis. A Langmuir‐Hinshelwood mechanism is found to represent the ODH reactions. The developed model fits the experimental data with favorable statistical indicators. The estimated specific reaction rate constants are also found to be consistent with the product selectivity data. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-31T18:50:22.655638-05:
      DOI: 10.1002/aic.15491
       
  • Ionic liquids in supercritical methanol greatly enhance
           transesterification reaction for high‐yield biodiesel production
    • Abstract: Biodiesel production is one of the most promising future alternatives to replacing fossil fuels. This work studies the use of ionic liquids (ILs) as potential catalysts in supercritical methanol for biodiesel production from non‐edible oil. The transesterification reaction of karanja oil was investigated in supercritical methanol in the presence of two respective ionic liquids, [BMIM+][HSO4‐] and [Chol+][H2PO4‐]. The reaction was performed in a one‐step batch process at several temperatures and percentages by weight of catalyst (w/woil). The results obtained show that the ionic liquid [Chol+][H2PO4‐] allows a high yield of fatty acid methyl esters (FAMEs) to be achieved in a short reaction time (above 95% in 45 min). A catalytic mechanism is also proposed for the ionic liquid that offered significant catalytic activity. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-31T18:45:21.800097-05:
      DOI: 10.1002/aic.15488
       
  • Immersed Boundary Method (IBM) Based Direct Numerical Simulation of
           Open‐cell Solid Foams: Hydrodynamics
    • Authors: Saurish Das; Niels G. Deen, J.A.M. Kuipers
      Abstract: A sharp interface implicit Immersed Boundary Method (IBM) is developed and used for direct numerical simulations of the flow through open‐cell solid foams with a cellular structure. The complex solid structure of the foam is resolved on a non‐boundary fitted Cartesian computational‐grid. A single representative unit cell of the foam is considered in a periodic domain, and its geometry is approximated based on the structural packing of a tetrakaidecahedron. Simulations are performed for a wide range of porosities (0.638‐0.962) and Reynolds numbers (0‐500). Flow is enforced by applying a constant body force (momentum source) for three different flow directions along the {100}, {110} and {111} lattice‐vectors. The drag force on the foam is calculated and a non‐dimensional drag/pressure drop correlation is proposed that fits the entire data set with an average deviation of $5.6\%$. Moreover, the accurate numerical simulations have helped to elucidate the detailed fluid‐solid interaction in complex porous media. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-29T04:05:23.35459-05:0
      DOI: 10.1002/aic.15487
       
  • Characterization of liquid‐liquid flows in horizontal pipes
    • Authors: Jing Shi; Hoi Yeung
      Abstract: Diverse flow regimes have been encountered in liquid‐liquid flows. Some degree of consistency in the observed flow patterns is shown in reported studies, while inconsistency exits when physical properties of the two phases concerned are wide enough. An attempt was made in this study to investigate the mechanisms behind flow patterns of liquid‐liquid flows in horizontal pipes. A literature review on flow patterns of liquid‐liquid flows in horizontal pipes was conducted. The ratio of the gravitational force to viscous force was proposed to characterize liquid‐liquid flows in horizontal pipes into gravitational force dominant, viscous force dominant, and gravitational force and viscous force comparable flow featured with different basic flow regimes. Comparisons of the proposed characterization criterion with the literature data show good agreement. © 2016 American Institute of Chemical Engineers AIChE J, 2016
      PubDate: 2016-08-26T13:45:29.23281-05:0
      DOI: 10.1002/aic.15452
       
  • CO2 abatement in oscillating packed‐bed scrubbers: Hydrodynamics and
           reaction performances for marine applications
    • Abstract: Gas‐liquid flow dynamics and CO2‐monoethanolamine absorption performances of an oscillating countercurrent packed bed were analyzed by means of a transient 3D nonisothermal two‐fluid flow model with a goal to understand the behavior of scrubbing units on‐board floating production, storage and offloading platforms. Gas‐liquid flow deviation from axial symmetry was significant at larger vessel inclinations prompting noticeable liquid accumulation in the column lowermost area. Conversely, in static vertical and slightly inclined columns only a reduced fraction of the liquid was subject to transverse segregation. Externally‐generated column oscillations brought about complex secondary flows in radial and tangential directions resulting in oscillatory patterns with amplitude and propagation frequency affected by the packed bed oscillations. CO2 abatement in inclined and asymmetrically oscillating columns suffered perceptible deviations with respect to vertical configuration while symmetrically oscillating columns gave rise to CO2 performances oscillating around the steady‐state solutions of the vertical column. © 2016 American Institute of Chemical Engineers AIChE J, 2016
      PubDate: 2016-08-26T13:40:29.574968-05:
      DOI: 10.1002/aic.15450
       
  • Curing Kinetics of Bio‐based Epoxy Resin Based on Epoxidized Soybean Oil
           and Green Curing Agent
    • Authors: Yahua Chen; Zhenhao Xi, Ling Zhao
      Abstract: New thermosets with high bio‐based content was synthesized by curing epoxidized soybean oil (ESO) with a green curing agent maleopimaric acid (MPA) catalyzed by 2‐ethly‐4‐methylimidazole (EMI). Non‐isothermal differential scanning calorimetry (DSC) and a relatively new integral isoconversional method were used to analyze the curing kinetic behaviors and determine the activation energy (Ea). The two‐parameter Šesták–Berggren autocatalytic model was applied in the mathematical modeling to obtain the reaction orders and the pro‐exponential factor. For anhydride/epoxy group molar ratio equal to 0.7, Ea decreased from 82.70 kJ/mol to 80.17 kJ/mol when increasing the amount of catalyst from 0.5 to 1.5 phr toward ESO. The reaction orders m and n were 0.4148 and 1.109, respectively. The predicted non‐isothermal curing rates of Šesták–Berggren model matched perfectly with the experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-25T17:45:47.159219-05:
      DOI: 10.1002/aic.15486
       
  • Novel model for the sintering of ceramics with bimodal pore size
           distributions: Application to the sintering of lime
    • Authors: Juan C. Maya; Farid Chejne, Suresh K. Bhatia
      Abstract: A mathematical model for the sintering of ceramics with bimodal pore size distributions at intermediate and final stages is developed. It considers the simultaneous effects of coarsening by surface diffusion, and densification by grain boundary diffusion and lattice diffusion. This model involves population balances for the pores in different zones determined by each porosimetry peak, and is able to predict the evolution of pore size distribution function, surface area, and porosity over time. The model is experimentally validated for the sintering of lime and it is reliable in predicting the so called “initial induction period” in sintering, which is due to a decrease in intra‐aggregate porosity offset by an increase inter‐aggregate porosity. In addition, a novel methodology for determination of mechanisms based on the analysis of the pore size distribution function is proposed, and with this, it was demonstrated that lattice diffusion is the controlling mechanism in the CaO sintering. © 2016 American Institute of Chemical Engineers AIChE J, 2016
      PubDate: 2016-08-25T09:16:03.635521-05:
      DOI: 10.1002/aic.15446
       
  • On the temperature control in a micro structured packed bed reactor for
           methanation of CO/CO2 mixtures
    • Authors: Michael Belimov; David Metzger, Peter Pfeifer
      Abstract: Micro reactor technology is widely used for process intensification and is essential for fast and strongly exothermic reactions exhibiting mass and heat transfer limitations. In the scope of the MINERVE Power‐to‐Gas project, sponsored by KIC InnoEnergy from 2012‐2015, a micro packed bed reactor was developed for conversion of syngas containing CO2 into methane. This work focuses on heat removal and temperature control in a manufactured device using syngas throughputs less than 1.4 Nm3/h (10% CO, 7% CO2, H2/C=4) while examining the cooling potential of different cooling fluids e.g. air, steam and water. The benefits of the system are elucidated and compared against present technologies. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-22T08:35:27.653418-05:
      DOI: 10.1002/aic.15461
       
  • Dehydrogenation of ethane to ethylene via radical pathways enhanced by
           alkali metal based catalyst in oxysteam condition
    • Authors: Kazuhiro Takanabe; Salman Shahid
      Abstract: The dehydrogenation of ethane to ethylene in the presence of oxygen and water was conducted using Na2WO4/SiO2 catalyst at high temperatures. At 923 K, the conversion rate without water was proportional to ethane pressure and a half order of oxygen pressure, consistent with a kinetically relevant step where an ethane molecule is activated with dissociated oxygen on the surface. When water was present, the ethane conversion rate was drastically enhanced. An additional term in the rate expression was proportional to a quarter of the oxygen pressure and a half order of the water pressure. This mechanism is consistent with the quasi‐equilibrated OH radical formation with subsequent ethane activation. The attainable yield can be accurately described by taking the water contribution into consideration. At high conversion levels at 1073 K, the C2H4 yield exceeded 60% in a single‐pass conversion. The C2H4 selectivity was almost insensitive to the C2H6 and O2 pressures. © 2016 The
      Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 2016
      PubDate: 2016-08-21T11:05:26.523259-05:
      DOI: 10.1002/aic.15447
       
  • Influence of ionic liquid composition on the stability of PVC‐based
           ionic liquid inclusion membranes in aqueous solution
    • Abstract: Membrane technology has gained significant importance with the incorporation of ionic liquids into their structure. This work shows the influence of ionic liquid composition on the stability of PVC‐based polymer ionic liquid inclusion membranes (PILIMs) in aqueous solution. Among the ILs investigated, those membranes which contain between 20 ‐ 30%w/w of the least soluble, [OMIM+][PF6‐] and [OMIM+][Ntf2‐], exhibit losses of IL lower than 10%. For both ILs, the amount immobilized was maximum for the membranes with 30%w/w of IL (0.0838 and 0.0832 g, respectively). On the contrary, the ionic liquid loss increases as its solubility in water increase, reaching 99.52% when PILIMs are prepared with 70%w/w of [OMIM+][BF4‐]. The results demonstrate that the stability of PILIMs depends on the solubility of the IL in the surrounding phase and the specific interaction between the IL and the polymeric support for PVC‐to‐IL ratios higher than 30%w/w. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-20T03:56:08.781953-05:
      DOI: 10.1002/aic.15460
       
  • Particle size effect on the catalyst attrition in a lab‐scale
           fluidized bed
    • Authors: Dongfang Wu; Fanghua Wu, Yongdan Li
      Abstract: Catalysts readily suffer from particle attrition in fluidized beds. In this paper, a commercial FCC catalyst was sieved into several particle‐size intervals to investigate the size effect on particle attrition. It is shown that an exponential decay equation presents a suitable description of attrition and that catalyst attrition is dependent on particle size. Steady‐state specific attrition rate decreases with increasing particle size; however, initial specific attrition rate and decay time parameter change irregularly. For comparison of attrition resistances, a long attrition test is required to reach steady‐state attrition, and the steady‐state specific attrition rate is recommended. It is seen that the smallest particle‐size interval is the most seriously attrited, while the two largest particle‐size intervals are the most attrition‐resistant. Furthermore, weak interactions appear among attrition behaviors of different intervals, and a linear combination method is effective to combine all interval samples to predict the attrition of the original full‐sized sample. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-19T04:05:43.754845-05:
      DOI: 10.1002/aic.15458
       
  • Scaling of Continuous Twin Screw Wet Granulation
    • Abstract: Scaling rules were developed and tested for a continuous twin screw wet granulation process using three scales (11mm, 16mm and 24mm barrel diameter) of twin screw granulators (TSG). The distributive feed screw (DFS) configuration used produced high porosity granules (50‐60%) with broad bimodal size distributions, especially in the 16mm and 24mm TSGs. Three dimensionless numbers, Froude number (Fr), liquid‐to‐solid ratio (LSR), and powder feed number (PFN), were identified and their effect on granule size distribution, porosity and liquid distribution tested. Granule size increased with increasing LSR as expected. However, Fr and PFN had no significant effect on d10 or d50 and only a small effect on d90. In contrast, granulator scale had a strong effect on granule size distribution, with d90 increasing almost linearly with barrel diameter. This is consistent with breakage of large granules being a dominant mechanism and directly controlled by the geometry of the screw. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-19T04:05:32.353007-05:
      DOI: 10.1002/aic.15459
       
  • Enhancing liquid micromixing using low‐frequency rotating
           nanoparticles
    • Abstract: Magnetic nanofluid actuation by rotating magnetic fields was proposed as a high‐performance tool for liquid mixing with enhanced micromixing features. A comparative study was conducted to evaluate the mixing index in T‐type mixers of magnetic and non‐magnetic fluids subject to static (SMF), oscillating (OMF) and rotating (RMF) magnetic fields. RMF excitation unveiled superior mixing indices with strong dependences to magnetic field frequency and content of magnetic nanoparticles. The impact of magnetic field types on micromixing was further examined at low and moderate Re numbers using the Villermaux‐Dushman reaction and IEM micromixing model. The IEM‐inferred micromixing times were remarkably shorter by nearly 4 orders of magnitude in comparison with OMF and SMF excitations, and without magnetic field. The proposed mixing strategy is foreseen to complement innovative microfluidic devices with valuable mixing tools and methods for the diagnosis of the coupling between transport and intrinsic kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-17T17:50:49.083019-05:
      DOI: 10.1002/aic.15456
       
  • Thermo‐hydraulic analysis of refinery heat exchangers undergoing
           fouling
    • Abstract: A complete, systematic approach is presented for the analysis and characterization of fouling and cleaning in refinery heat exchangers. Bringing together advanced thermo‐hydraulic dynamic models, some new formulations, and a method for dynamic analysis of plant data, it allows: extracting significant information from the data; evaluating the fouling state of the units based on thermal measurements and pressure drops, if available; identifying the range of deposit conductivity leading to realistic pressure drops, if pressure measurements are unavailable; estimating key fouling and ageing parameters; estimating the effectiveness of cleaning and surface conditions after a clean; and predicting thermal and hydraulic performance with good accuracy for other periods/exchangers operating in similar conditions. An industrial case study demonstrates the performance prediction in seamless simulations that include partial and total cleanings for over 1000 days operation. The risks of using thermal effects alone and the significant advantages of including pressure drop measurements are highlighted. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-17T17:50:46.204889-05:
      DOI: 10.1002/aic.15457
       
  • Effect of Bed Characteristics on Local Liquid Spreading in a Trickle Bed
    • Authors: Arpit Jindal; Vivek V. Buwa
      Abstract: Trickle bed reactors are important to several chemical process applications. While the available CFD models can predict overall liquid volume fraction, the prediction of spatial liquid distribution continues to be a challenging task. In the present work, Eulerian multi‐fluid simulations were performed to investigate the effects of particle size, gas and liquid flow rates and bed structure on local liquid spreading and the predictions were validated using measured liquid spreading. It was found that the capillary pressure force caused liquid to spread in the lateral direction and that the interphase interaction forces pushed it in the downward direction and the relative magnitudes of these forces governed the local liquid distribution. While the use of existing capillary pressure force model led to satisfactory prediction of the observed trends of dynamic and steady state local liquid spreading, the modified capillary pressure force led to quantitatively correct predictions of local liquid spreading. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-17T17:50:41.640295-05:
      DOI: 10.1002/aic.15455
       
  • Current distribution in a rectangular flow channel manufactured by
           3D‐printing
    • Abstract: The characterization and improvement of the rectangular channel electrolyte flow compartment used in an iron‐air flow battery was carried out by using an arrangement of copper electrodes to measure the current density distribution employing the limiting current technique. The present work addresses the hydrodynamics and mass transport distribution in the compartment and their improvement by an improved electrolyte compartment that results in a more uniform current distribution. The current distribution was evaluated as the ratio between the local and the averaged limiting current densities during the reduction of copper ions over a range of mean linear flow velocity across the electrode surface (2‐30 cm s−1).The initial compartment, showed larger differences between the minimum and maximum currents than the electrolyte compartment that resulted as part of the design process and showed a higher pressure drop at a given mean linear flow velocity. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-17T03:30:39.51741-05:0
      DOI: 10.1002/aic.15454
       
  • Aerosol Analysis of Residual and Nanoparticle Fractions from Spray
           Pyrolysis of Poorly Volatile Precursors
    • Abstract: The quality of aerosol‐produced nanopowders can be impaired by micron‐sized particles formed due to non‐uniform process conditions. Methods to evaluate the quality reliably and fast, preferably on‐line, are important at industrial scales. Here, aerosol analysis methods are used to determine the fractions of nanoparticles and micron‐sized residuals from poorly volatile precursors. This is accomplished by using aerosol instruments to measure the number and mass size distributions of Liquid Flame Spray‐generated alumina and silver particles produced from metal nitrates dissolved in ethanol and 2‐ethylhexanoic acid (EHA). The addition of EHA had no effect on silver, whereas, 5\% EHA concentration was enough to shift the alumina mass from the residuals to nanoparticles. The size‐resolved aerosol analysis proved to be an effective method for determining the product quality. Moreover, the used on‐line techniques alone can be used to evaluate the process output when producing nanopowders, reducing the need for tedious off‐line analyses. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-11T23:40:36.689005-05:
      DOI: 10.1002/aic.15449
       
  • A Positron Emission Particle Tracking investigation of the scaling law
           governing free surface flows in tumbling mills
    • Authors: I. Govender; M. C. Richter, D. N. De Klerk, A. N. Mainza
      Abstract: Positron Emission Particle Tracking (PEPT) measurements are used to track the flow of d = 5mm glass beads within a rotating drum fitted with (and without) lifter bars and operated in the cascading and cataracting Froude regimes. After converting the Lagrangian trajectories of a representative radio‐labelled glass bead (the tracer) into Eulerian fields under the ergodic assumption, the bed shape and kinematics are extracted for steady, fully developed flow conditions. Notwithstanding the azimuthal wall effects introduced by the lifter bars, we show a linear scaling 〈v〉∝h of the local flowing layer thickness h with local depth‐averaged velocity 〈 v 〉and a constant average shear 〈γ̇〉∼0.6gd for direct measurements spanning the entire flowing layer (not just the central region), and high Froude regimes (cascading and cataracting) not previously investigated by scaling analysis in the literature. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-11T23:40:34.187218-05:
      DOI: 10.1002/aic.15453
       
  • Thermodynamic Analysis and Optimization of RWGS Processes for Solar Syngas
           Production from CO2
    • Abstract: Process systems were investigated for syngas production from CO2 and renewable energy (solar) by the reverse water‐gas shift (RWGS) and the reverse water‐gas shift chemical looping (RWGS‐CL) process. Thermodynamic analysis and optimization was performed to maximize the solar‐to‐syngas (StS) efficiency ηStS. Special emphasis was laid on product gas separation. For RWGS‐CL, a maximum StS efficiencies of 14.2 and 14.4% were achieved without and with heat integration, respectively. The StS efficiency is dictated by the low overall efficiency of H2 production. RWGS‐CL is most beneficial for the production of pure CO, where the StS efficiency is one percent point higher compared to that of the RWGS process with heat integration. Heat integration leads to significant reductions in external heat demand since most of the gas phase process heat can be integrated. The StS efficiencies for RWGS and RWGS‐CL achieve the same level as the reported values for solar thermochemical syngas production. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-11T03:45:57.466224-05:
      DOI: 10.1002/aic.15445
       
  • Engineering the outermost layers of TiO2 nanoparticles using in situ Mg
           doping in a flame aerosol reactor
    • Authors: Yanjie Hu; Yang Wang, Hao Jiang, Yunfeng Li, Theodore Cohen, Yi Jiang, Binqi Wang, Ling Zhang, Pratim Biswas, Chunzhong Li
      Abstract: Titanium dioxide nanoparticles with disordered outermost layer sturctures have significantly enhanced light absorption and photocatalytic properties and thus receiving enhanced attention in recent years. Engineering the outermost layers using in situ magnesium doping to tailor the band‐edge of TiO2 nanoparticles was achieved via a flame aerosol reactor (FLAR). We proposed that the distribution of doped elements in nanoparticles could be controlled in a high temperature flame process, and which could be predicted by the comparison of different characteristic time scales, such as reaction time, coagulation time, and sintering time. In situ magnesium doping on the outermost layers effectively tailored the conduction band and electron structure of the TiO2 nanoparticles, and simultaneously improved the maximum photocurrent as well as the maximum photovoltage in dye‐sensitized solar cells (DSSCs). These improvements were largely attributed to red‐shifted light absorption, and rapid photoelectron injection into the conduction band. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-10T18:20:29.866949-05:
      DOI: 10.1002/aic.15451
       
  • Understanding and Optimization of Chemical Reactor Performance for Bimodal
           Reaction Sequences
    • Authors: J. Poissonnier; J.W. Thybaut, G.B. Marin
      Abstract: The relative contributions of heterogeneously catalyzed and homogeneous bulk phase reactions in bimodal reaction sequences have been assessed via 1D reactor simulations. Starting from a reaction network only comprising 2 parallel, irreversible heterogeneously catalyzed and homogeneous bulk phase steps, complementary consecutive steps were included with the option of being reversible. The final product formed after a minimum number of homogeneous bulk phase reactions is obtained with high yields in continuous flow fixed bed reactors. The products obtained after a higher number of homogeneous bulk phase reactions generally dominate in slurry reactors. Yields of the latter may exhibit an optimum as a function of the catalyst amount in the reactor. The adsorption enthalpies of the intermediates in the reaction network critically determine the position and shape of this maximum. The reversibility of the homogeneous bulk phase steps provides specific opportunities to tune the product yields in bimodal reaction sequences. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-10T18:07:53.989404-05:
      DOI: 10.1002/aic.15448
       
  • Novel Operability‐based Approach for Process Design and Intensification:
           Application to a Membrane Reactor for Direct Methane Aromatization
    • Authors: Juan C. Carrasco; Fernando V. Lima
      Abstract: This paper introduces a novel operability‐based approach for process design and intensification of energy systems described by nonlinear models. This approach is applied to a membrane reactor (MR) for the direct methane aromatization (DMA) conversion to benzene and hydrogen. The proposed method broadens the scope of the traditional path of the operability approaches for design and control, mainly oriented to obtain the achievable output set (AOS) from the available input set (AIS), and compare the computed AOS to a desired output set (DOS). In particular, an optimization algorithm based on nonlinear programming tools is formulated for the calculation of the desired input set (DIS) that is feasible considering process constraints and intensification targets. Results on the application of the operability method as a tool for process intensification show reduction of the DMA‐MR footprint (≈ 77% reactor volume and 80% membrane area reduction) for an equivalent level of performance, when compared to the base case. This case study indicates that the novel approach can be a powerful tool for process intensification of membrane reactors and other complex chemical processes. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:52:37.69587-05:0
      DOI: 10.1002/aic.15439
       
  • Rheology of Cubic Particles in a Concentrated Colloidal Dispersion
           Suspending Medium
    • Authors: Colin D. Cwalina; Kelsey J. Harrison, Norman J. Wagner
      Abstract: The flow behavior of mixtures of micron‐sized cubic particles suspended in a concentrated colloidal dispersion is investigated across a broad range of cubic particle concentrations. In the semi‐dilute regime, the qualitative shape of the dynamic moduli and flow curves reflect those of the underlying colloidal dispersion medium. These curves are superimposed with the underlying colloidal dispersion using shift factors that are found to be larger than those obtained in a recent study of suspensions of non‐colloidal spherical particles in the same colloidal dispersion medium. At higher concentrations of cubic particles, deviations from this shifting procedure are apparent. Scaling calculations suggest depletion interactions are responsible for the increase in the low shear viscosity and confinement of the underlying colloidal dispersion can be expected to enhance the shear thickening behavior at high shear stresses. The results of this study provide guidance for formulating suspensions through control of particle shape and mixture concentration. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:48:12.810658-05:
      DOI: 10.1002/aic.15443
       
  • Slot coating flows of non‐colloidal particle suspensions
    • Authors: L. D. Valdez Silva; D. M. Campana, M. S. Carvalho
      Abstract: Slot coating is used in the manufacturing of functional films, which rely on specific particle microstructure to achieve the desired performance. Final structure on the coated film is strongly dependent on the suspension flow during the deposition of the coating liquid and on the subsequent drying process. Fundamental understanding on how particles are distributed in the coated layer enables optimization of the process and quality of the produced films.The complex coating flow leads to shear‐induced particle migration and non‐uniform particle distribution. We study slot coating flow of non‐colloidal suspensions by solving the mass and momentum conservation equations coupled with a particle transport equation using the Galerkin/Finite element method. The results show that particle distribution in the coating bead and in the coated layer is non‐uniform and is strongly dependent on the imposed flow rate (wet thickness). This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:48:11.670722-05:
      DOI: 10.1002/aic.15444
       
  • Adsorptive Cyclic Purification Process for CO2 Mixtures Captured from Coal
           Power Plants
    • Abstract: CO2 capture technology combined with bulk separation and purification processes has become an attractive alternative to reduce capture costs. Furthermore, the required purity in the application for CO2 conversion and utilization is more stringent than that required from a captured CO2 mixture for geological storage. In this study, an adsorptive cyclic purification process was developed to upgrade a CO2/N2 mixture captured from greenhouse gas emission plants as a feasibility study for a second capture unit or captured CO2 purifier. To purify 90% CO2 with balance N2 as a captured gas mixture, two‐bed PSA and PVSA processes using activated carbon were experimentally and theoretically studied at adsorption pressures of 250 to 650 kPa and a fixed vacuum pressure of 50 kPa. CO2 with higher than 95% purity was produced with more than 89% recovery. However, a four‐bed PVSA process could successfully produce CO2 with greater than 98% purity and 90% recovery. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:48:10.55249-05:0
      DOI: 10.1002/aic.15440
       
  • Review of the Important Challenges and Opportunities related to Modeling
           of Mammalian Cell Bioreactors
    • Authors: Parham Farzan; Biren Mistry, Marianthi G. Ierapetritou
      Abstract: Industrialization of mammalian cell culture has been achieved by integrating knowledge from several applying core concepts of chemical engineering, cellular and molecular biology, and biochemistry. Modeling has been applied to biological and physical processes to gain additional insights into such processes. This paper covers modeling of the bioreactor and metabolic processes as it applies to bioprocess. Hydrodynamics of a bioreactor is briefly described while additional focus is given to gas‐liquid mass transfer. Biological modeling is presented in the order of increasing complexity. First steady state models are presented followed by dynamic models, cybernetic models and finally bioreactor integrated models. The closing discussion summarizes challenges of implementation of model‐based approaches in the biopharmaceutical industry. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:48:04.40111-05:0
      DOI: 10.1002/aic.15442
       
  • In‐situ adaptive tabulation for the CFD simulation of heterogeneous
           reactors based on operator‐splitting algorithm
    • Authors: Mauro Bracconi; Alberto Cuoci, Matteo Maestri
      Abstract: We apply the In‐Situ Adaptive Tabulation algorithm to efficiently solve the chemical sub‐step in the context of the simulation of heterogeneous reactors. A numerical strategy ‐ specifically conceived for unsteady simulation of catalytic devices ‐ has been developed and interfaced in the context of the operator splitting technique with the solution of the chemical sub‐step, which requires 70%‐90% of the total computational time. The algorithm performances have been illustrated by considering a single channel of a honeycomb reactor operating the catalytic partial oxidation of methane and a methane steam reforming packed bed reactor. We found out that the application of ISAT resulted in a speed‐up of the chemical step up to ∼500 times with an overall speed‐up of ∼5‐15 times for the whole simulation. Such reduction of the computation effort is key to make affordable fundamental CFD simulations of chemical reactors at a level of complexity relevant to technological applications. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:47:40.601711-05:
      DOI: 10.1002/aic.15441
       
  • Continuous Reactive Crystallization of Pharmaceuticals Using Impinging Jet
           Mixers
    • Authors: Wen J. Liu; Cai Y. Ma, Jing J. Liu, Yang Zhang, Xue Z. Wang
      Abstract: For reactive crystallization of pharmaceuticals that show a rapid reaction rate, low solubility of active pharmaceutical ingredient and hence a large supersaturation, it was found in a recent study that a process design which integrates an impinging jet mixer and batch stirred tank produces high quality crystals. The current investigation examines if the short processing time of reactive crystallization permits the impinging jet mixer ‐ stirred tank design to be modified to operate in a continuous mode. The new design combines an impinging jet mixer for feed introduction and reaction with a continuous stirred tank reactor (CSTR) and tubular reactor for crystal growth. A study of reactive crystallization of sodium cefuroxime (an antibiotic), using firstly a 1L CSTR then scaling to a 50L CSTR, found that the new design produces crystals of higher crystallinity, narrower particle size, and improved product stability, than batch crystallizers. This article is protected by copyright. All rights reserved.
      PubDate: 2016-08-02T03:41:22.836284-05:
      DOI: 10.1002/aic.15438
       
  • Particle Dynamics and Relaxation in Bimodal Suspensions during Drying
           Using Multi‐speckle Diffusing Wave Spectroscopy
    • Authors: Gwi Jeong Oh; Ji Won Hwang, Seong Jae Lee, Ki Wan Bong, Hyun Wook Jung
      Abstract: The motion of polystyrene particles in a bimodal suspension drop during drying was characterized via multi‐speckle diffusing wave spectroscopy. The fast and slow dynamics of bimodal particles, which were expressed in terms of autocorrelation function data from two kinds of cameras, were well connected in short and long lag time regimes. Characteristic time of β‐relaxation, representing the rapid movement of bimodal particles, became lower in the short lag time region as the portion of small particles increased, reflecting their fast Brownian motion. The difference in the relaxation features between bimodal suspension with large and small particles and unimodal suspension with only large particles became more evident as the size ratio between particles was high. Drying temperature could encourage the particle movement at the early stages of drying, leading to lower relaxation time, and inversely retard the relaxation behavior when drying time further elapsed, due to the structural rearrangement of particles. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-23T03:25:32.064819-05:
      DOI: 10.1002/aic.15437
       
  • A Water Droplet Size Distribution Dependent Modeling of Hydrate Formation
           in Water/Oil Emulsion
    • Abstract: Experimental data on chord length distributions and growth rate during methane hydrate formation in water‐in‐oil emulsions were obtained in a high pressure stirring reactor using FBRM and PVM. The experiments were carried out at 274.2 K for 10%‐30% water cuts and agitation rates ranging from 200 to 500 rpm initially at 7.72 MPa. Rapid growth was accompanied by gradually decrease in rate. Free water was observed to become depleted during rapid growth while some water remained encapsulated inside hydrate layers constituting a mass transfer barrier. The apparent kinetic constants of methane hydrate formation and free‐water fractions were determined using a newly developed kinetic model independent of the dissolution rate at the gas‐oil interface. It was illustrated that continued growth depends on distribution and transfer of water in oil‐dominated systems. This perception accords with observations of hydrate film growth on suspended water droplet in oil and clarifies transfer limits in kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-23T03:25:31.068071-05:
      DOI: 10.1002/aic.15436
       
  • Identification of Cell‐Nucleation Mechanism in Foam Injection Molding
           with Gas‐counter Pressure via Mold Visualization
    • Authors: Vahid Shaayegan; Guilong Wang, Lun Howe Mark, Chul B. Park
      Abstract: The mechanisms of cell nucleation and growth are investigated in foam injection molding using gas‐counter pressure (GCP). An in‐situ mold visualization technique is employed. The application of GCP suppresses cell nucleation, and prevents the blowing agent from escaping during mold‐filling. The inherent structural heterogeneity in the regular foam injection molding can be improved because of the uniform cavity pressure when employing GCP. The cavity pressure profiles show much faster pressure‐drop rates using GCP, because the single‐phase polymer/gas mixture has a lower compressibility than the two‐phase polymer/bubble mixture. Therefore, both the cell nucleation and growth rates are significantly increased through a higher pressure‐drop rate upon the removal of the GCP. The effect of GCP magnitude on the cell morphology is explored. When the GCP is lower than the solubility pressure, bimodal foaming occurs. As the GCP increases above the solubility pressure, the cell density increases because of the higher pressure‐drop rate. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-23T02:50:38.033947-05:
      DOI: 10.1002/aic.15433
       
  • Experimental operation of a reactive dividing wall column and comparison
           with simulation results
    • Authors: Christoph Ehlers; Torben Egger, Georg Fieg
      Abstract: Reactive dividing wall columns (RDWC) are a special type of distillation column that allow for the targeted realization of chemical reactions and the separation into multiple product fractions in one shell. However, despite their huge economical and ecological potentials for certain fields of application, this innovative technology has not found its way into industrial production processes yet. The very limited availability of experimental research studies verifying the prediction capabilities of respective modeling concepts for this type of distillation column might be one decisive reason for that. Therefore, the present study puts its focus on the detailed comparison between experimental operation of RDWC and the corresponding simulation results for steady‐state. For the first time, the mentioned comparison is carried out for a chemical system with non‐negligible side reactions. It is shown that even for this highly complex system, the mathematical model is capable of predicting the column operation. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-20T18:10:23.105795-05:
      DOI: 10.1002/aic.15435
       
  • Krypton‐Xenon Separation Properties of SAPO‐34 Zeolite
           Materials and Membranes
    • Authors: Yeon Hye Kwon; Christine Kiang, Emily Benjamin, Phillip Crawford, Ramesh Bhave, Sankar Nair
      Abstract: Separation of the radioisotope 85Kr from 136Xe is an important target during used nuclear fuel recycling. We report a detailed study on the Kr and Xe adsorption, diffusion, and membrane permeation properties of the silicoaluminophosphate zeolite SAPO‐34. Adsorption and diffusion measurements on SAPO‐34 crystals indicate their potential for use in Kr‐Xe separation membranes, but also highlight competing effects of adsorption and diffusion selectivity. SAPO‐34 membranes are synthesized on α−alumina disk and tubular substrates via steam assisted conversion (SAC) seeding and hydrothermal growth, and are characterized in detail. Membrane transport measurements reveal that SAPO‐34 membranes can separate Kr from Xe by molecular sieving, with Kr permeabilities around 50 Barrer and mixture selectivity of 25‐30 for Kr at ambient or slight sub‐ambient conditions. The membrane transport characteristics are modeled by the Maxwell‐Stefan equations, whose predictions are in very good agreement with experiment and confirm the minimal competing effects of adsorption and diffusion. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-20T10:30:37.513337-05:
      DOI: 10.1002/aic.15434
       
  • Adsorption of iodine on hydrogen‐reduced silver‐exchanged mordenite:
           Experiments and modelling
    • Authors: Yue Nan; David W. DePaoli, Lawrence L. Tavlarides
      Abstract: The adsorption process of iodine, a major volatile radionuclide in the off‐gas streams of spent nuclear fuel reprocessing, on hydrogen‐reduced silver‐exchanged mordenite (Ag0Z) was studied at the micro‐scale. The gas‐solid mass transfer and reaction involved in the adsorption process were investigated and evaluated with appropriate models. Optimal conditions for reducing the silver‐exchanged mordenite (AgZ) in a hydrogen stream were determined. Kinetic and equilibrium data of iodine adsorption on Ag0Z were obtained by performing single‐layer adsorption experiments with experimental systems of high precision at 373 – 473 K over various iodine concentrations. Results indicate approximately 91% to 97% of the iodine adsorption was through the silver‐iodine reaction. The effect of temperature on the iodine loading capacity of Ag0Z was discussed. The Shrinking Core model describe the data well, and the primary rate controlling mechanisms were macro‐pore diffusion and silver‐iodine reaction. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-14T18:32:20.989268-05:
      DOI: 10.1002/aic.15432
       
  • Synthesizing bromobutyl rubber by a microreactor system
    • Authors: Pei Xie; Kai Wang, Peijian Wang, Yang Xia, Guangsheng Luo
      Abstract: Bromobutyl rubber (BIIR) is an important synthetic rubber with better vulcanizing behavior than traditional butyl rubber (IIR). It is hard to synthesize for the high reactant viscosity and strong corrosion caused by Br2 and HBr. A microreactor platform was developed to solve the corrosion problem with cheap materials and obtain high quality BIIR based on microscaled mixing. The results showed that low reaction temperature and quickly eliminating HBr from the reacting solution were crucial to obtain high selectivity of demanded molecule structure and prevent polymer from decomposition. Owing to the corrosion resistance ability, a water assistant technology was successfully implemented in the microreactor system, which produced high quality BIIR with almost 100% selectivity and less reduced molecule weight. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T18:45:24.516304-05:
      DOI: 10.1002/aic.15431
       
  • A new optimization model and a customized solution method for natural gas
           production network design and operation
    • Authors: Dan Li; Xiang Li
      Abstract: This paper proposes to tackle integrated design and operation of natural gas production networks under uncertainty, using a new two‐stage stochastic programming model, a novel reformulation strategy, and a customized global optimization method. The new model addresses material balances for multiple key gas components, pressure flow relationships in gas wells and pipelines, and compressor performance. This model is a large‐scale nonconvex mixed‐integer nonlinear programming problem that cannot be practically solved by existing global optimization solvers or decomposition‐based optimization methods. With the new reformulation strategy, the reformulated model has a better decomposable structure, and then a new decomposition‐based global optimization method is developed for efficient global optimization. In the case study of an industrial naturals production system, it is shown that the proposed modeling and optimization methods enable efficient solution, and the proposed optimization method is faster than a state‐of‐the‐art decomposition method by at least an order of magnitude. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T17:55:52.225316-05:
      DOI: 10.1002/aic.15428
       
  • Error‐triggered on‐line model identification for
           model‐based feedback control
    • Authors: Anas Alanqar; Helen Durand, Panagiotis D. Christofides
      Abstract: In industry, it may be difficult in many applications to obtain a first‐principles model of the process, in which case a linear empirical model constructed using process data may be used in the design of a feedback controller. However, linear empirical models may not capture the nonlinear dynamics over a wide region of state‐space and may also perform poorly when significant plant variations and disturbances occur. In the present work, an error‐triggered on‐line model identification approach is introduced for closed‐loop systems under model‐based feedback control strategies. The linear models are re‐identified on‐line when significant prediction errors occur. A moving horizon error detector is used to quantify the model accuracy and to trigger the model re‐identification on‐line when necessary. The proposed approach is demonstrated through two chemical process examples using a model‐based feedback control strategy termed Lyapunov‐based economic model predictive control (LEMPC). The chemical process examples illustrate that the proposed error‐triggered on‐line model identification strategy can be used to obtain more accurate state predictions to improve process economics while maintaining closed‐loop stability of the process. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T17:55:49.258028-05:
      DOI: 10.1002/aic.15430
       
  • Improving the operational stability of the multi‐chamber spout‐fluid
           bed via the insertion of a submerged partition plate
    • Authors: Shiliang Yang; Yuhao Sun, Liangqi Zhang, Jia Wei Chew
      Abstract: The effect of a submerged partition plate on improving the gas‐solid flow robustness and stability in a three‐dimensional spout‐fluid bed with multiple inter‐connected chambers is numerically investigated by means of computational fluid dynamics coupled with discrete element method (CFD‐DEM). Notably, multiple‐chamber beds are necessary in scaling up the spout‐fluid bed. The influence of plate height on gas‐solid distribution, spout‐annulus interaction and chamber interaction are also studied to optimize the design. The results demonstrate that inserting a partition plate with height above a certain threshold can effectively improve the stability of spouting and uniformly re‐distribute the flux load in each chamber, giving rise to parallel fountains and lower circulation flux of the solid phase. Results indicate that the plate height should be at least 80% of the packed bed height investigated, with the most optimal being about 92% based on steady spouting, and the maximum solid and gas exchanging fluxes between the chambers. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T17:55:47.909722-05:
      DOI: 10.1002/aic.15427
       
  • Structure‐based model for prediction of electrical conductivity of
           pure ionic liquids
    • Abstract: A structure‐based method was proposed to estimate the electrical conductivity of ionic liquids covering wide ranges of temperature (238.15‐484.1 K) and electrical conductivity (0.0001524‐19.3 S/m) based on experimental data collect from literature from 1998 to 2015. The influences of temperature and ion structure on electrical conductivity were also discussed. The mean absolute percentage error between the calculated and literature data was 6.02%, with 6.12% for the training set (1978 data points, 177 ILs) and 5.10% for the test set (217 data points, 11 ILs). This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T17:55:45.298651-05:
      DOI: 10.1002/aic.15429
       
  • Simulation of dry powder inhalers: Combining micro‐scale, meso‐scale
           and macro‐scale modeling
    • Abstract: The flow of carrier particles, coated with active drug particles, is studied in a prototype dry powder inhaler. A novel, multi‐scale approach consisting of a discrete element model (DEM) to describe the particles coupled with a dynamic large eddy simulation (LES) model to describe the dynamic nature of the flow is applied. The model consists of three different scales: the micro‐scale, the meso‐scale and the macro‐scale. At the micro‐scale, the interactions of the small active drug particles with larger carrier particles, with the wall, with the air flow, and with each other is thoroughly studied using discrete element modelling and detailed computational fluid dynamics (CFD), i.e resolving the flow structures around the particles. This has led to the development of coarse‐grained models, describing the interaction of the small active drug particles at the larger scales.At the meso‐scale the larger carrier particles, and all of their interactions are modelled individually using DEM and CFD‐LES. Collisions are modeled using a visco‐elastic model to describe the local deformation at each point of particle‐particle contact in conjunction with a model to account for cohesion.At the macro‐scale, simulations of a complete prototype inhaler are carried out. By combining the relevant information of each of the scales, simulations of the inhalation of one dose from a prototype inhaler using a patient relevant air flow profile show that fines leave the inhaler faster than the carrier particles. The results also show that collisions are not important for particle‐particle momentum exchange initially but become more important as the particles accelerate. It is shown that for the studied prototype inhaler the total release efficiency of the fine particles is between 10% and 30%, depending on the Hamaker constant, using typical settings for the properties of both particles. The results are also used to study regions of recirculation, where carrier particles can become trapped, and regions where fines adhere to the wall of the device. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-13T17:55:41.430245-05:
      DOI: 10.1002/aic.15424
       
  • Modeling Study for the Effect of Particle Size on Char Gasification with
           CO2
    • Authors: Zhongjie Shen; Jianliang Xu, Haifeng Liu, Qinfeng Liang
      Abstract: This study applied a high temperature stage microscope to investigate the temperature effect caused by particle size on char gasification. Experiments were carried out with different particle sizes for raw chars and chars on molten slag surface, respectively. Heat transfer models were built for the raw char of two temperature distributions and char particle on molten slag, respectively. Results showed that reaction layer temperature of raw char decreased in the reaction dominant while char on molten slag had higher temperature. Temperature difference between two distributions increased with the initial particle size, indicating the temperature effect on large particles was obvious. Shrinking core model was applied and modified herein coupled with the modification of reaction layer temperature and reaction area. Model prediction and experimental data showed good agreements of carbon conversion and reactivity index for raw char and char on molten slag, respectively. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:30:56.517164-05:
      DOI: 10.1002/aic.15417
       
  • Resolved‐particle Fixed Bed CFD with Microkinetics for Ethylene
           Oxidation
    • Authors: Behnam Partopour; Anthony G. Dixon
      Abstract: The incorporation of an ethylene oxidation microkinetic model into fixed‐bed CFD is studied using two different approaches. The first is based on mapping pre‐calculated reaction rates into quadratic splines under steady‐state conditions without any further assumptions or simplification of the elementary steps. The second approach uses conventional reaction engineering assumptions such as quasi‐equilibrium (QE) and hybrid steady state (HSS) to reduce the kinetic model and generate lumped rate expressions. Both kinetic models are implemented for illustrative resolved‐particle CFD simulations in a randomly packed bed of 120 spheres. It is shown that the QE and HSS assumptions are not valid throughout the range of reacting conditions. Comparison of the temperature and species profiles for these two approaches shows that the strong gradients inside the bed cause significant deviations in the reduced model compared to using the splines method with full microkinetics, which produces accurate results without increasing the computational time. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:25:38.199862-05:
      DOI: 10.1002/aic.15422
       
  • Influence of Catalyst Pore Network Structure on the Hysteresis of
           Multiphase Reactions
    • Abstract: The effects of the catalyst pore network structure on multiphase reactions in catalyst pellets are investigated by using the experimentally validated pore network model proposed in our recent work (AIChE J. 2016, 62, 451). The simulations display hysteresis loops of the effectiveness factor. The hysteresis loop area becomes significantly larger, when having small volume‐averaged pore radius, wide pore size distribution, and low pore connectivity; however, the loop area is insensitive to pellet size, even though it affects the value of the effectiveness factor. The hysteresis loop area is also strongly affected by the spatial distribution of the pore size, in particular for a bimodal pore size distribution. The pore network structure directly influences mass transfer, capillary condensation, and pore blocking, and subsequently passes these influences on to the hysteresis loop of the effectiveness factor. Recognizing these effects is essential when designing porous catalysts for multiphase reaction processes. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:20:53.108119-05:
      DOI: 10.1002/aic.15415
       
  • A Simple Model for Predicting Solid Concentration Distribution in
           Binary‐solid Liquid Fluidised Beds
    • Authors: Zhengbiao Peng; Behdad Moghtaderi, Elham Doroodchi
      Abstract: A simple mathematical model for predicting the solid concentration profile in binary‐solid liquid fluidised beds is presented. The main assumption is that the solid concentration distribution follows the logistic function, which is supported by the literature. Various equations have been derived to solve key system quantities (e.g., bed expansion height, length and position of the transition zone). In contrast to previous models that often involve adjustable parameters and strongly rely on the availability of experimental data, the present model only requires inputs of fluid and particle properties, operating conditions and correlations for dispersion and slip velocity. The results showed that the model is applicable to different binary‐solid systems that have size and/or density differences. The model's capability of predicting the layer inversion phenomenon has also been demonstrated. The model is simple but proves capable of accurately predicting key information for the design, operation and scale up of liquid fluidised beds. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:20:37.772202-05:
      DOI: 10.1002/aic.15420
       
  • Operational Strategy and Planning for Raw Natural Gas Refining Complexes:
           Process Modeling and Global Optimization
    • Authors: B. J. Zhang; Q. L. Chen, Jie Li, C. A. Floudas
      Abstract: Optimal operational strategy and planning of a raw natural gas refining complex (RNGRC) is very challenging since it involves highly nonlinear processes, complex thermodynamics, blending, and utility systems. In this paper, we first propose a superstructure integrating a utility system for the RNGRC, involving multiple gas feedstocks and different product specifications. Then, we develop a large‐scale nonconvex mixed‐integer nonlinear programming (MINLP) optimization model. The model incorporates rigorous process models for input and output relations based on fundamentals of thermodynamics and unit operations and accurate models for utility systems. To reduce the noncovex items in the proposed MINLP model, equivalent reformulation techniques are introduced. Finally, the reformulated nonconvex MINLP model is solved to global optimality using state of the art deterministic global optimization approaches. The computational results demonstrate that a significant profit increase is achieved using the proposed approach compared to that from the real operation. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:20:36.307135-05:
      DOI: 10.1002/aic.15416
       
  • An Experimental and Theoretical Study of Glycerol Oxidation to
           1,3‐Dihydroxyacetone over Bimetallic Pt‐Bi Catalysts
    • Abstract: It is important to utilize glycerol, the main by‐product of biodiesel, to manufacture value‐added chemicals such as 1,3‐dihydroxyacetone (DHA). In the present work, the performance of five different catalysts (Pt‐Bi/AC, Pt‐Bi/ZSM‐5, Pt/MCM‐41, Pt‐Bi/MCM‐41 and Pt/Bi‐doped‐MCM‐41) was investigated experimentally, where Pt‐Bi/MCM‐41 was found to exhibit the highest DHA yield. To better understand the experimental results and to obtain insight into the reaction mechanism, density functional theory (DFT) computations were conducted to provide energy barriers of elementary steps. Both experimental and calculated results show that for high DHA selectivity, Bi should be located in an adatom‐like configuration Pt, rather than inside Pt. A favorable pathway and catalytic cycle of DHA formation were proposed based on the DFT results. A cooperative effect, between Pt as the primary component and Bi as a promoter, was identified for DHA formation. Both experimental and theoretical considerations demonstrate that Pt‐Bi is efficient to convert glycerol to DHA selectively. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-11T03:20:25.989465-05:
      DOI: 10.1002/aic.15418
       
  • Computing MOSCED Parameters of Nonelectrolyte Solids with Electronic
           Structure Methods in SMD and SM8 Continuum Solvents
    • Authors: Jeremy R. Phifer; Kimberly J. Solomon, Kayla L. Young, Andrew S. Paluch
      Abstract: An efficient method to predict MOSCED parameters for nonelectrolyte solids using electronic structure calculations in SMD and SM8 continuum solvents is proposed and applied to acetanilide, acetaminophen, and phenacetin. The resulting parameters are ultimately used to predict the equilibrium solubility in a range of solvents over a range of temperatures. By combining MOSCED with SMD and SM8, we are able to leverage the strengths of both methods while eliminating shortcomings that would prevent their use alone for solvent selection in design processes involving nonelectrolyte solid solutes. Comparing to 77 non‐aqueous experimental solubilities of acetaminophen over the range 10 to 30 $^\circ$C, the proposed method has an average absolute error of 0.03 and 0.04 mol fracs for SMD and SM8 regressed parameters, respectively. Aqueous solubilities of acetaminophen over this temperature range are predicted with an average error of 0.030 and 0.0023 mol fracs, respectively. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-08T04:26:29.035354-05:
      DOI: 10.1002/aic.15413
       
  • Power consumption and form drag of regular and fractal‐shaped
           turbines in a stirred tank
    • Authors: K. Steiros; P. J. K. Bruce, O. R. H. Buxton, J. C. Vassilicos
      Abstract: Previous wind‐tunnel measurements have shown that fractal shaped plates have increased drag compared to square plates of the same area. In this study we measure the power consumption and drag of turbines with fractal and rectangular blades in a stirred tank. Power number decreases from rectangular to fractal impellers by over 10\%, increasingly so with fractal iteration number. Our results suggest that this decrease is not caused by the wake interaction of the blades, nor solely by the wake interaction with the walls either.Pressure measurements on the blades' surface show that fractal blades have lower drag than the rectangular ones, opposite to the wind tunnel experiment results. All tested blades' centre of pressure radius increases with Re, while their drag coefficient decreases, a possible effect of the solid body rotation increase with Re. Spectral analysis of the pressure signal reveals two peaks possibly connected to the blades' roll vortices. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-08T04:26:27.930102-05:
      DOI: 10.1002/aic.15414
       
  • Surface DEAE Groups Facilitate Protein Transport on Polymer Chains in
           DEAE‐Modified‐and‐DEAE‐Dextran‐Grafted Resins
    • Authors: Linling Yu; Lingli Gong, Shu Bai, Yan Sun
      Abstract: Sepharose FF was modified with diethylaminoethyl‐dextran (DEAE‐dextran, DexD) and/or DEAE (D) to fabricate three types of ion exchangers FF‐DexD (grafting‐ligand resin), FF‐D (surface‐ligand resin), and FF‐D‐DexD (mixed‐ligand resin), for protein adsorption equilibria and kinetics study. It was found that both adsorption capacity and uptake rate (effective diffusivity, De) were significantly enhanced by grafting DEAE‐dextran. Notably, the De values on FF‐DexD and FF‐D‐DexD (De/D0>1.4) were six times greater than those on FF‐D (De/D0
      PubDate: 2016-07-08T04:26:07.594004-05:
      DOI: 10.1002/aic.15412
       
  • Loading of fibrous filter media and newly designed filter configurations
           by salt particles: An experimental study
    • Authors: Pengfei Zhao; Peng Cheng, Bruce J. Tatarchuk
      Abstract: Various fibrous filter media, including surface filter media, depth filter media, woven and nonwoven filter media, were tested and particle loading capacity was calculated using bench‐scale setup via a new estimation approach which was proposed and experimentally verified with Novick‐Kozeny model. Multi‐Element Structured Arrays (MESAs) developed by our research group were evaluated as well for particle loading capacity and filter lifetime on 24” × 24” full scale test rig (based on ASHRAE 52.2 Standard). Effects of varying filter media type, filter depth, pleat count and MESAs' element count on salt particle loading performance were experimentally investigated. The experimental studies showed that nonwoven activated carbon fiber (ACF) filter media have allowed significantly higher salt particle loading capacity and longer useful lifetime compared to woven or nanofiber entrapped media. Furthermore, MESAs were able to significantly enhance loading capacity for salt particles and useful lifetime due to higher filtration area and lower filtration velocity. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-04T18:35:32.124745-05:
      DOI: 10.1002/aic.15407
       
  • Strategy to improve catalytic trend predictions for methane oxidation and
           reforming
    • Authors: Byeongjin Baek; Abraham Aboiralor, Jacob D. Massa, Shengguang Wang, Purnima Kharidehal, Lars C. Grabow
      Abstract: Computational catalysts screening is an increasingly popular technique, in which the mechanism from a known good catalyst is commonly adopted, parameterized from linear scaling relationships, and then used a microkinetic model to identify other metal alloys with incrementally improved activity. This strategy, however, fails to identify truly novel catalysts that operate under non‐traditional reaction conditions and exhibit alternative dominant reaction pathways. Using methane oxidation and reforming we investigated a series of O* and OH*‐assisted C‐H scission and C‐O bond formation pathways. Notably, for methane oxidation we discovered a second local optimum for O*‐assisted C‐H bond activation near Ag, which is inactive if only the direct C‐H scission route is considered. In light of the significant qualitative difference in the predicted catalytic trends when parallel mechanisms are allowed, we propose a minimum barrier assumption to rapidly screen for potentially important alternative pathways without the need for costly density functional theory simulations. This article is protected by copyright. All rights reserved.
      PubDate: 2016-07-04T18:35:31.515331-05:
      DOI: 10.1002/aic.15404
       
  • Visualization and simulation of the transfer process of index‐matched
           silica microparticle inks for gravure printing
    • Authors: A.M.P. Boelens; S. Lim, B.Y. Ahn, L. Francis, J.A. Lewis, J.J. de Pablo
      Abstract: A combined experimental and computational study of the transfer of transparent index‐matched silica‐particle inks between two flat plates is presented for gravure printing applications. The influence of printing speed and initial ink droplet size on the ability to accurately transfer ink during the printing process is explored systematically. Smooth interface Volume Of Fluid simulations are able to capture experimentally observed ink transfer over a wide range of printing speeds for inks having a modest to intermediate content of silica particles. However, for high‐content silica‐particle inks, transfer is structurally underpredicted. Our calculations indicate that for ink droplets with characteristic dimensions in the vicinity of 10, which are of particular interest for gravure printing applications, ink transfer improves due to the diminishing effect of gravity, and the increased importance of capillary forces at small length scales. This article is protected by copyright. All rights reserved.
      PubDate: 2016-06-27T13:25:23.67395-05:0
      DOI: 10.1002/aic.15392
       
  • A Comparative Computational Study of Diesel Steam Reforming in a Catalytic
           Plate Heat‐Exchange Reactor
    • Authors: Harsh Dhingra; Mayur Mundhwa, Rajesh D. Parmar
      Abstract: A two‐dimensional steady‐state model of a catalytic plate reactor for diesel steam reforming is developed. Heat is provided indirectly to endothermic reforming sites by flue gas from a SOFC tail‐gas burner. Two experimentally‐validated kinetic models on diesel reforming on platinum (Pt) catalyst were implemented for a comparative study; the model of Parmar et al.19 for a Pt/Al2O3 and the model of Shi et al.20 for a Pt/Gd‐CeO2 (GDC). The kinetic models were compared for: species concentration, approach to equilibrium, gas hourly space velocity and effectiveness factor. Co‐current flow showed better heat transfer compared to counter‐current flow arrangement. The comparison between the two kinetic models showed that different supports plays significant role in the final design of a reactor. The study also determined that initial 20% of the plate reactor has high diffusion limitation suggesting to use graded catalyst to optimize the plate reactor performance. This article is protected by copyright. All rights reserved.
      PubDate: 2016-06-24T22:25:28.431356-05:
      DOI: 10.1002/aic.15391
       
  • Macro‐Economic Multi‐Objective Input‐Output Model for Minimizing CO2
           Emissions: Application to the U.S. Economy
    • Abstract: Designing effective environmental policies for mitigating global warming is a very challenging task that requires detailed knowledge of the international channels through which goods are traded. This work presents a decision‐support tool that minimizes the impact at a global macroeconomic scale by performing changes in the economic sectors of an economy. Our tool combines multi‐objective optimization, environmentally extended input‐output tables and life cycle assessment within a unified framework. Our results on the US economy to minimize CO2 emissions identify sectors that should be regulated first to reach a given environmental target while maximizing the demand satisfaction. The impact of shale gas is also studied. Our findings show that the application of process systems engineering tools at a macroeconomic level can provide valuable insight for public policy makers into problems of general interest. This article is protected by copyright. All rights reserved.
      PubDate: 2016-06-15T03:40:40.611982-05:
      DOI: 10.1002/aic.15376
       
  • Issue information ‐ table of contents
    • Pages: 3517 - 3517
      PubDate: 2016-09-02T09:30:03.995182-05:
      DOI: 10.1002/aic.14998
       
  • New materials for catalysis and energy storage devices
    • Authors: Harold H. Kung
      Pages: 3518 - 3528
      PubDate: 2016-07-13T10:17:51.194376-05:
      DOI: 10.1002/aic.15386
       
  • Cohesive grains: Bridging microlevel measurements to macrolevel flow
           behavior via surface roughness
    • Authors: Peiyuan Liu; Casey Q. LaMarche, Kevin M. Kellogg, Stuart Leadley, Christine M. Hrenya
      Pages: 3529 - 3537
      Abstract: Significance Understanding fine‐particle flows relies on van der Waals cohesion modeling, requiring a method to consider measured surface roughness. A robust scheme to extract roughness parameters from AFM surface maps, achieving accurate predictions of microscale measured cohesion is proposed. Macroscale quantitative agreement is demonstrated by comparing defluidization predictions to measurements, which are sensitive to cohesion and system‐size independent. Agreement in both microscale and macroscale comparisons highlights the role of individual particle properties on bulk granular systems. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3529–3537, 2016
      PubDate: 2016-07-11T09:57:40.664706-05:
      DOI: 10.1002/aic.15383
       
  • A high‐throughput assay for screening modifiers of calcium oxalate
           crystallization
    • Authors: Sriram Ramamoorthy; Jun Ha Kwak, Pankaj Karande, Sahar Farmanesh, Jeffrey D. Rimer
      Pages: 3538 - 3546
      Abstract: Controlling crystal habit using growth modifiers provides novel avenues for tailoring properties of crystalline materials. Here, we report on the design of a high‐throughput screening assay for rapid identification of growth modifiers using calcium oxalate monohydrate crystallization as a model system. We conducted a systematic study of assay parameters (sample volume, shaking, and temperature) on crystallization kinetics. Crystallization half‐time (t1/2), defined as the time at which crystallization is 50% complete, was obtained from the logistic fit of kinetic data and used as a measure of growth modifier potency. A test library of 13 peptides composed of aspartic acid and alanine residues was screened to determine their growth promotion or inhibition potentials. Leads identified from this study are in good agreement with ion‐selective electrode measurements and a single time point measurement of free calcium ion concentration is an excellent end‐point for evaluating modifier potency. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3538–3546, 2016
      PubDate: 2016-07-11T09:50:31.095612-05:
      DOI: 10.1002/aic.15390
       
  • Non‐intrusive characterization of particle size changes in fluidized
           beds using recurrence plots
    • Pages: 3547 - 3561
      Abstract: An on‐line method is developed for monitoring of mean particle size in fluidized beds using pressure fluctuations (PFs) and acoustic emissions (AE) signal by recurrence plot (RP) and recurrence quantification analysis (RQA). PFs and AE signals of a lab‐scale fluidized bed were measured simultaneously at various superficial gas velocities and mean particle sizes. Although the AE signals are often very complicated due to many different acoustic sources in the bed, applying RP analyses showed that small changes in mean particle size can be detected by visual comparison of AE‐RP structures, while this cannot be distinguished by graphical RP analysis of PFs. Moreover, the hydrodynamics of the bed was inspected through RQA analysis of both signals. For this purpose, recurrence rate, determinism, laminarity, average length of diagonal and vertical lines were extracted from RPs showing the effect of an increase in the mean particle size. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3547–3561, 2016
      PubDate: 2016-04-26T10:25:53.894591-05:
      DOI: 10.1002/aic.15265
       
  • A soft‐sphere‐imbedded pseudo‐hard‐particle model for simulation
           of discharge flow of brick particles
    • Authors: Nan Gui; Xingtuan Yang, Shengyao Jiang, Jiyuan Tu
      Pages: 3562 - 3574
      Abstract: A novel hybrid approach of soft‐sphere‐imbedded pseudo‐hard‐particle model is proposed to cope with the complex collision of nonspherical particles. In this approach, the boundary of a host hard particle is covered by a series of soft‐spheres, which are allowed to oscillate about the equilibrium position according to the position, orientation, and shape configuration of the host particle. The collision processes are twofold: as a predictive process, particle‐particle interaction takes place through the collision between the distributed soft‐spheres, which causes subspheres to deviate from the equilibrium positions; as a corrective process, relaxation is superposed to allow the soft‐spheres to move back toward the equilibrium positions quickly. Consequentially, this process generates the force and torque on the host particle and determines its movement. Finally, after validation, this new model is used to explore the effects of aspect ratio and base angle on the discharge of brick particles in hoppers. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3562–3574, 2016
      PubDate: 2016-05-05T09:40:40.075287-05:
      DOI: 10.1002/aic.15278
       
  • Three‐component solids velocity measurements in the outlet section
           of a riser
    • Pages: 3575 - 3584
      Abstract: Coincident (simultaneous) three‐component particle velocity measurements performed using two laser Doppler anemometry probes at the outlet section of a 9 m high cylindrical riser are for the first time presented for dilute flow conditions. Near the blinded extension of the T‐outlet a solids vortex is formed. Particle downflow along the riser wall opposite the outlet tube is observed, which is restricted to higher riser heights at higher gas flow rates. Increased velocity fluctuations are observed in the solids vortex and downflow region as well as at heights corresponding to the outlet tube. Contrary to the rest of the riser, in the downflow region time and ensemble velocity averages are not equal. Given the local bending of the streamlines, axial momentum transforms to radial and azimuthal momentum giving rise to the corresponding shear stresses. Turbulence intensity values indicate the edges of the downflow region. © 2016 The
      Authors AIChE Journal published by Wiley Periodicals, Inc. on behalf of American Institute of Chemical Engineers AIChE J, 62: 3575–3584, 2016
      PubDate: 2016-05-06T14:15:37.625549-05:
      DOI: 10.1002/aic.15277
       
  • Linking micro‐scale predictions of capillary forces to macro‐scale
           fluidization experiments in humid environments
    • Authors: Casey Q. LaMarche; Andrew W. Miller, Peiyuan Liu, Christine M. Hrenya
      Pages: 3585 - 3597
      Abstract: The effects of increasing relative humidity (RH) on fluidization/defluidization are investigated experimentally and understood via particle‐level predictions for the resulting capillary force. Experimentally, defluidization is found to be more sensitive to small changes in RH than fluidization. This sensitivity is captured by a new defluidization velocity Udf, which characterizes the curvature of the defluidization plot (pressure drop vs. velocity) observed between the fully‐fluidized (constant pressure drop) and packed‐bed (linear pressure drop dependence on velocity) states; this curvature is indicative of a partially‐fluidized state arising from humidity induced cohesion. Plots of Udf vs. RH reveal two key behaviors, namely Udf gradually increases with a relatively constant slope, followed by an abrupt increase at RH ∼55%. Furthermore, the bed transitions from Group A to Group C behavior between RH of approximately 60–65%. From a physical standpoint, these macro‐scale trends are explained via a theory for capillary forces that, for the first time, incorporates measured values of particle surface roughness. Specifically, a model for the cohesive energy of rough surfaces in humid environments shows the same qualitative behavior as Udf vs. RH for RH
      PubDate: 2016-05-06T14:05:29.684954-05:
      DOI: 10.1002/aic.15281
       
  • Impact of problem formulation on LNG process optimization
    • Pages: 3598 - 3610
      Abstract: The power consumption of a single mixed‐refrigerant process (PRICO®) for natural gas liquefaction was minimized using four different constraint formulations to handle the trade‐off between investment and operating costs. Aspen HYSYS® was used for process simulation, while a sequential quadratic programming algorithm (NLPQLP) was used for optimization. The results confirm that optimal utilization of the heat exchanger area is only obtained with a constraint based on a maximum heat exchanger conductance (UA). The minimum temperature difference constraint commonly used in process design gives a significant energy penalty as it is incapable of accounting for the distribution of driving forces with respect to temperature, the nonlinearity of the composite curves and the trade‐off between driving forces and cooling load. The results also indicate that the maximum UA constraint leads to increased complexity of the optimization problem, and that the success rate of the optimization method used therefore is reduced. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3598–3610, 2016
      PubDate: 2016-05-04T08:25:54.260067-05:
      DOI: 10.1002/aic.15266
       
  • Nested direct transcription optimization for singular optimal control
           problems
    • Authors: Weifeng Chen; Lorenz T. Biegler
      Pages: 3611 - 3627
      Abstract: Singular optimal control problems arise frequently on a broad range of chemical engineering applications. Determination of the accurate dynamic structure of the optimal solution profile and the junctions between optimal nonsingular and singular arcs is essential for operating strategies, as well as equipment designs for many processes. In a previous study (Chen, Shao, and Biegler, AIChE J. 60(3), pp. 966–979, 2014) a nested optimization formulation that finds the optimal mesh distribution and determines exact control profiles for nonsingular optimal control problems without state constraints is developed. This study extends this approach to singular optimal control problems. To satisfy the necessary optimality conditions for singular optimal control problems with a well‐defined solution strategy, the overall nonlinear programming formulation resulting from direct transcription is decomposed into inner and outer problems. The key feature of this algorithm is that it converges to a solution that satisfies the discretized Euler‐Lagrange equations of the original singular optimal control problem; we prove this under suitable assumptions. This is obtained through the introduction of pseudomultipliers that reconstruct the necessary optimality conditions for singular optimal control in the outer problem. We demonstrate this approach on eight classical singular control problems with known solutions, as well as three larger singular control problems derived from chemical engineering applications. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3611–3627, 2016
      PubDate: 2016-05-04T08:30:54.470563-05:
      DOI: 10.1002/aic.15272
       
  • Covariance‐based hardware selection part IV: Solution using the
           generalized benders decomposition
    • Authors: Jin Zhang; Xiaoxi Wang, Donald J. Chmielewski
      Pages: 3628 - 3638
      Abstract: Recently the covariance based hardware selection problem has been shown to be of the mixed integer convex programming (MICP) class. While such a formulation provides a route to global optimality, use of the branch and bound search procedure has limited application to fairly small systems. The particular bottleneck is that during each iteration of the branch and bound search, a fairly slow semi‐definite programming (SDP) problem must be solved to its global optimum. In this work, we illustrate that a simple reformulation of the MICP and subsequent application of the generalized Benders decomposition algorithm will result in massive reductions in computational effort. While the resulting algorithm must solve multiple mixed integer linear programs, this increase in computational effort is significantly outweighed by the reduction in the number of SDP problems that must be solved. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3628–3638, 2016
      PubDate: 2016-05-09T09:51:03.471163-05:
      DOI: 10.1002/aic.15285
       
  • Low‐temperature and highly efficient conversion of saccharides into
           formic acid under hydrothermal conditions
    • Authors: Jun Yun; Guodong Yao, Fangming Jin, Heng Zhong, Atsushi Kishita, Kazuyuki Tohji, Heiji Enomoto, Li Wang
      Pages: 3657 - 3663
      Abstract: Production of formic acid, which has been regarded as an important H2 carrier, from biomass can be a highly potential way to provide human societies with renewable energy source. To attain economically viable production of formic acid from biomass on an industrial scale, the system operation at low reaction temperature is crucially important. In this work, a low‐temperature hydrothermal conversion of carbohydrates such as monosaccharides and disaccharides into formic acid is reported. A good formic acid yield of 80–85% was obtained at a lower temperature of 423 K for only 15–20 min in the presence of NaOH without any other catalyst. The alkali was found to act as two roles in enhancing the production of formic acid. One was inhibition of the formic acid decomposition; another was favorable for the oxidation selectively at C‐1 for aldoses, which leads to the formation of formic acid via the rupture of the C1–C2 bond. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3657–3663, 2016
      PubDate: 2016-05-05T09:30:24.374915-05:
      DOI: 10.1002/aic.15287
       
  • Novel inexpensive transition metal phosphide catalysts for upgrading of
           pyrolysis oil via hydrodeoxygenation
    • Authors: Cheng Guo; Kasanneni Tirumala Venkateswara Rao, Ehsan Reyhanitash, Zhongshun Yuan, Sohrab Rohani, Chunbao (Charles) Xu, Sophia (Quan) He
      Pages: 3664 - 3672
      Abstract: Supported molybdenum/molybdenum‐phosphides as inexpensive catalysts for bio‐oil hydrodeoxygenation (HDO) were in‐house prepared using different support materials, i.e., Al2O3, activated carbon (AC), MgAl2O4, and Mg6Al2(CO3)(OH)16. The HDO activity of these catalysts were investigated using a 100 mL bench‐scale reactor operating at 300°C with an initial hydrogen pressure of 50 bar for 3 h with a pyrolysis oil (PO). The catalytic efficiencies for bio‐oil HDO for the catalysts were compared with the expensive but commercially available Ru/C catalyst. Addition of small amount of P to the Mo catalysts supported on either AC and Al2O3 led to increased degree of deoxygenation (DOD) and oil yield compared with those without P. MoP supported on AC (MoP/AC) demonstrated bio‐oil HDO activity comparable to the Ru/C catalyst. Furthermore, three AC‐supported metal phosphides for PO HDO were compared under the same conditions, and they were found to follow the order of NiP/AC > CoP/AC > MoP/AC. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3664–3672, 2016
      PubDate: 2016-05-06T10:46:00.533755-05:
      DOI: 10.1002/aic.15286
       
  • Kinetics of the absorption of carbon dioxide into aqueous ammonia
           solutions
    • Pages: 3673 - 3684
      Abstract: Experiments were performed in a customized double stirred tank reactor to study the kinetics of CO2 absorption into NH3 solutions at concentrations ranging from 0.42 to 7.67 kmol·m−3 and temperatures between 273.15 and 293.15 K. The results show that the reactive absorption was first order with respect to CO2 but fractional order (1.6–1.8) with respect to ammonia. Experimental data can be satisfactorily interpreted by a termolecular mechanism using kNH3T=7.6089×108exp⁡(−4018.4T) and kH2OT=7.9161×107exp⁡(−4356.4T). © 2016 American Institute of Chemical Engineers AIChE J, 62: 3673–3684, 2016
      PubDate: 2016-06-22T14:50:35.486407-05:
      DOI: 10.1002/aic.15296
       
  • Countercurrent Droplet‐flow‐based mini extraction with pulsed feeding
           and without moving parts
    • Authors: Cong Xu; Shan Jing, Yifeng Chu
      Pages: 3685 - 3698
      Abstract: A countercurrent arrangement of immiscible liquid‐liquid mini contactors based on droplets is described in this article. Mini mixers without any moving parts were used as the contactors. The single stage mini mixer consists of a top and bottom mixing chamber. Both of the mixing chambers have two recirculating channels on either side. In these mini mixers, a liquid was broken up into droplets that dispersed into other continuously flowing liquid, consequently achieving a mass transfer between the two liquids. To realize the countercurrent arrangement, the two liquids were alternately fed into the system from opposite ends by compressed air according to a periodic program. One period consists of the following stages: organic phase feeding stage, droplet aggregation stage I, aqueous phase feeding stage, and droplet aggregation stage II. This continuous countercurrent arrangement is without the defects of continuous countercurrent arrangements based on laminar flows and multiple‐stage countercurrent arrangements based on droplets. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3685–3698, 2016
      PubDate: 2016-04-22T14:40:51.428044-05:
      DOI: 10.1002/aic.15267
       
  • On thermodynamic separation efficiency: Adsorption processes
    • Authors: Ryan P. Lively; Matthew J. Realff
      Pages: 3699 - 3705
      Abstract: A simplified thermodynamic analysis of adsorption processes in temperature swing adsorption (TSA) and pressure swing adsorption (PSA) modes as a function of adsorbate concentration and the adsorbent–adsorbate interaction strength is presented in this article. The thermodynamic separation efficiency of a TSA process is optimal at dilute feed conditions, and becomes more thermodynamically efficient with increasing adsorbate affinity even though the energy of separation increases. The adsorption process is spontaneous, and for a strong isotherm, the energy required to reverse the adsorption is nearly independent of the adsorbate concentration as adsorbate loading in nearly‐saturated materials is essentially constant with feed concentration. PSA units are efficient thermodynamically and the efficiency increases with the concentration of the desired adsorbate. This thermodynamic treatment has implications for separation processes that address carbon emissions. TSA systems operate more efficiently (thermodynamically) in the “air capture” case because they apply work to the concentrated product rather than the dilute feed. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3699–3705, 2016
      PubDate: 2016-04-22T14:45:44.578362-05:
      DOI: 10.1002/aic.15269
       
  • Functionalized metal‐organic polyhedra hybrid membranes for aromatic
           hydrocarbons recovery
    • Pages: 3706 - 3716
      Abstract: Pervaporation membranes are potentially useful in the separation of aromatic/aliphatic mixtures. Wherein, the membrane material plays a key role. Herein, a series of functionalized metal‐organic polyhedra (MOPs)/hyperbranched polymer hybrid membranes are molecularly designed and fabricated for the recovery of aromatic hydrocarbons. The isostructural MOP molecules with different functional groups are uniform in shape/size and soluble in solvents, which enable them to disperse well and be compatible in/with the polymer. Pervaporation results demonstrated significant improvements of these membranes in separation performances. Particularly, the membrane with MOP‐SO3NanHm showed the separation factor of 8.03 and the permeation flux of 528 g/m2h for the recovery of toluene from its 50 wt % n‐heptane mixture, and those values are 8.4 and 540 g/m2h for benzene/cyclohexane mixture. We propose that the selectivity of these membranes is affected primarily by the polarity of functional groups in MOPs, which were further explained by the adsorption experiments and molecular simulations. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3706–3716, 2016
      PubDate: 2016-04-26T10:30:49.961606-05:
      DOI: 10.1002/aic.15263
       
  • Modeling and performance prediction of chromate reduction by iron oxide
           coated sand in adsorber reactors
    • Authors: Ryan Thacher; Varadarajan Ravindran, Massoud Pirbazari
      Pages: 3717 - 3729
      Abstract: Iron oxide coated sand (IOCS) as an adsorbent medium for removing hexavalent chromium (Cr(VI)) from industrial wastewater, as well as in permeable reactive barriers for remediation of Cr(VI) in aquifers is investigated in this study. An important feature was the use of a mathematical model for performance forecasting and process upscaling of IOCS fixed‐bed adsorber systems for Cr(VI) removal. Another significance aspect was the elucidation of IOCS surface mechanisms and interactions responsible for Cr(VI) sorption and reduction to the less toxic Cr(III). The adsorption equilibrium and mass‐transfer parameters for modeling were obtained from independent laboratory studies. Adsorber studies validated the predictive model and established the effectiveness of IOCS for Cr(VI) removal under different conditions. Model simulation studies demonstrated that adsorbent capacity, surface diffusion, and film transfer significantly influenced process dynamics. The study showed that IOCS can be used to remove Cr(VI) from contaminated waters, meeting the overall objectives of regulatory agencies. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3717–3729, 2016
      PubDate: 2016-05-05T09:20:35.573102-05:
      DOI: 10.1002/aic.15257
       
  • A novel carbonized polydopamine (C‐PDA) adsorbent with high CO2
           adsorption capacity and water vapor resistance
    • Authors: Shikai Xian; Feng Xu, Zhenxia Zhao, Yingwei Li, Zhong Li, Qibin Xia, Jing Xiao, Haihui Wang
      Pages: 3730 - 3738
      Abstract: Novel carbonized polydopamine adsorbents (C‐PDAs) with high surface area, high CO2 adsorption capacity and superior moisture resistance performance were prepared by one‐step synthesis method using polydopamine as carbon precursor at different KOH/C ratios, and then characterized. CO2 and water vapor adsorption performances of C‐PDAs were examined separately by static adsorption and fixed‐bed experiments. Results showed that BET area and pore volume of C‐PDA‐4 were up to 3342 m2/g and 2.01 cm3/g, respectively. Its CO2 adsorption capacity reached up to 30.5 mmol/g at 25 bar, much higher than many other adsorbents including metal‐organic frameworks (MOFs). C‐PDAs prepared with high KOH/C ratios had low surface element concentrations of O and N resulting in low surface hydrophilic property. H2O(g) isotherm of C‐PDA was much lower than those on Mg‐MOF‐74, Cu‐BTC, and MIL‐101(Cr). Fixed‐bed experiments showed that co‐presence of water vapor in feed stream with 30% RH had negligible impact on CO2 working capacity of C‐PDA. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3730–3738, 2016
      PubDate: 2016-05-09T09:36:16.993848-05:
      DOI: 10.1002/aic.15283
       
  • Forced convection boiling in a stator–rotor–stator spinning
           disc reactor
    • Authors: M. M. de Beer; J. T. F. Keurentjes, J. C. Schouten, J. van der Schaaf
      Pages: 3763 - 3773
      Abstract: Boiling of a pure fluid inside the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, average temperature driving force ΔT and mass flow rate ϕm. The average boiling heat transfer coefficient hb increases a factor 3 by increasing ω up to 105 rad s−1, independently of ΔT and ϕm. The performance of the srs‐SDR, in terms of hb vs. specific energy input ϵ, is similar to tubular boiling, where pressure drop provides the energy input. The srs‐SDR enables operation at ϵ>105 WmR−3, yielding values of hb not practically obtainable in passive evaporators, due to prohibitively high pressure drops required. Since hb is increased independently of the superficial vapor velocity, hb is not a function of ϕm and the local vapor fraction. Therefore, the srs‐SDR enables a higher degree of control and flexibility of the boiling process, compared to passive flow boiling. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3763–3773, 2016
      PubDate: 2016-04-26T10:20:58.504499-05:
      DOI: 10.1002/aic.15274
       
  • Transport and deposition kinetics of polymer‐coated multiwalled carbon
           nanotubes in packed beds
    • Authors: Ngoc H. Pham; Jeffrey H. Harwell, Daniel E. Resasco, Dimitrios V. Papavassiliou, Changlong Chen, Benjamin Shiau
      Pages: 3774 - 3783
      Abstract: In this study, a modified filtration equation that accounts for the transport and kinetics of polymer‐coated multiwalled carbon nanotubes in columns packed with crushed Berea sandstone is presented. The columns were saturated with brine solution, in which the salt concentration was varied from 0 to 10 wt%. Experimental results show that the polymer effectively eliminates the effects of salt on particle deposition when the salt concentration is less than or equal to 10 wt%. The calculated cumulative particle recovery is as high as 88.47 ± 0.25%. Results show that, at 10 wt% salt concentration, the proposed equation successfully predicts the experimental behavior, especially at the early stages of the breakthrough, where commonly used models fail. It is argued that the new equation accounts for the dynamic change of single collector efficiency as the deposition process advances. When tested against prior results available in the literature, the proposed model agrees with published data from other investigators. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3774–3783, 2016
      PubDate: 2016-04-28T09:16:07.750283-05:
      DOI: 10.1002/aic.15273
       
  • Convective condensation in a stator–rotor–stator spinning disc
           reactor
    • Authors: Michiel M. de Beer; Jos T. F. Keurentjes, Jaap C. Schouten, John van der Schaaf
      Pages: 3784 - 3796
      Abstract: Centrifugal intensification of condensation heat transfer in the rotor–stator cavities of a stator–rotor–stator spinning disc reactor (srs‐SDR) is studied, as a function of rotational velocity ω, volumetric throughflow rate ϕv, and average temperature driving force ΔT. For the current range of ω, heat transfer from the vapor bubbles to the condensate liquid is limiting, due to a relatively low gas–liquid interfacial area aGL. For ω>84 rad s−1, a strong increase of aGL, results in increasing the reactor‐average condensation heat transfer coefficient hc from 1600 to 5600 W m−2 K−1, for condensation of pure dichloromethane vapor. Condensation heat transfer in the srs‐SDR is enhanced by rotation, independent of the vapor velocity. The intensified condensation comes at the cost of relatively high energy dissipation rates, indicating condensation in the srs‐SDR is more suited as a means to supply heat (e.g. in an intensified reactor‐heat exchanger), rather than for bulk cooling purposes. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3784–3796, 2016
      PubDate: 2016-05-06T14:10:36.004673-05:
      DOI: 10.1002/aic.15275
       
  • Numerical modeling of the cooling cycle and associated thermal stresses in
           a melt explosive charge
    • Authors: Warren Sanhye; Charles Dubois, Isabelle Laroche, Pierre Pelletier
      Pages: 3797 - 3811
      Abstract: A comprehensive simulation tool is developed to describe and optimize the cooling cycle in the melt‐casting of Composition B. It comprises a multiphysics approach tackling heat, mass, and momentum transfers involved in the casting process. The highly nonlinear solidification step and development of thermal stresses are included. A V & V (Verification and Validation) approach was adopted whereby the model was verified against a benchmark problem and tested with a simple cylindrical geometry. Then, the approach was applied to a 105 mm caliber artillery shell and simulation results were in close agreement with experimental measurements. The model is equipped with a CZM function to account for adhesion between the solidified cast and the mold. During cooling, separation is possible and the size and location of gaps, depending on shrinkage and adhesion, are successfully emulated. The importance of controlled solidification is pointed out, especially regarding steep temperature gradients within the shell. © 2016 American Institute of Chemical Engineers AIChE J, 62: 3797–3811, 2016
      PubDate: 2016-05-09T09:46:18.287263-05:
      DOI: 10.1002/aic.15288
       
  • Erratum
    • Pages: 3820 - 3821
      PubDate: 2016-06-17T14:50:29.082081-05:
      DOI: 10.1002/aic.15348
       
  • Erratum
    • Pages: 3822 - 3823
      PubDate: 2016-07-12T10:18:23.560938-05:
      DOI: 10.1002/aic.15375
       
 
 
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