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  Subjects -> ENGINEERING (Total: 2285 journals)
    - CHEMICAL ENGINEERING (192 journals)
    - CIVIL ENGINEERING (185 journals)
    - ELECTRICAL ENGINEERING (104 journals)
    - ENGINEERING (1206 journals)
    - ENGINEERING MECHANICS AND MATERIALS (383 journals)
    - HYDRAULIC ENGINEERING (55 journals)
    - INDUSTRIAL ENGINEERING (69 journals)
    - MECHANICAL ENGINEERING (91 journals)

ENGINEERING (1206 journals)            First | 1 2 3 4 5 6 7 | Last

Showing 201 - 400 of 1205 Journals sorted alphabetically
CTheory     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Current Science     Open Access   (Followers: 62)
Dams and Reservoirs     Hybrid Journal   (Followers: 4)
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: 28)
Designed Monomers and Polymers     Open Access   (Followers: 2)
Designs, Codes and Cryptography     Hybrid Journal   (Followers: 7)
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: 5)
Developments in Mineral Processing     Full-text available via subscription   (Followers: 3)
Diálogos Interdisciplinares     Open Access  
Diffusion Foundations     Full-text available via subscription   (Followers: 3)
Digital Signal Processing     Hybrid Journal   (Followers: 23)
Dinamika Rekayasa     Open Access  
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: 2)
DYNA Minas     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: 5)
Electrophoresis     Hybrid Journal   (Followers: 17)
Elementos     Open Access  
Elsevier Geo-Engineering Book Series     Full-text available via subscription   (Followers: 3)
Elsevier Ocean Engineering Series     Full-text available via subscription   (Followers: 1)
Embedded Systems Letters, IEEE     Hybrid Journal   (Followers: 42)
Emitter : International Journal of Engineering Technology     Open Access  
ENERGETIKA. Proceedings of CIS higher education institutions and power engineering associations     Open Access   (Followers: 1)
Energies     Open Access   (Followers: 4)
Energy and Power Engineering     Open Access   (Followers: 21)
Energy Conversion and Management     Hybrid Journal   (Followers: 11)
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: 5)
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: 13)
ENGEVISTA     Open Access   (Followers: 1)
ENGI : Revista Electrónica de la Facultad de Ingenieria     Open Access   (Followers: 1)
Engineer : Journal of the Institution of Engineers, Sri Lanka     Open Access  
Engineering     Open Access   (Followers: 2)
Engineering & Technology     Hybrid Journal   (Followers: 23)
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: 4)
Engineering Economics     Open Access   (Followers: 5)
Engineering Economist, The     Hybrid Journal   (Followers: 5)
Engineering Failure Analysis     Hybrid Journal   (Followers: 69)
Engineering Geology     Hybrid Journal   (Followers: 10)
Engineering International     Open Access  
Engineering Management Journal     Hybrid Journal   (Followers: 21)
Engineering Management Research     Open Access   (Followers: 7)
Engineering Management Reviews     Open Access   (Followers: 1)
Engineering Optimization     Hybrid Journal   (Followers: 11)
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: 6)
Engineering, Technology & Applied Science Research     Open Access  
Entramado     Open Access  
Entropy     Open Access   (Followers: 5)
Environmental & Engineering Geoscience     Full-text available via subscription   (Followers: 4)
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: 5)
Ergonomics in Design: The Quarterly of Human Factors Applications     Hybrid Journal   (Followers: 17)
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: 5)
ESAIM: Proceedings     Open Access   (Followers: 1)
Estuaries and Coasts     Hybrid Journal   (Followers: 17)
European Journal of Combinatorics     Full-text available via subscription   (Followers: 5)
European Journal of Engineering Education     Hybrid Journal   (Followers: 4)
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: 4)
European Physical Journal - Applied Physics     Full-text available via subscription   (Followers: 16)
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: 13)
Fibers and Polymers     Full-text available via subscription   (Followers: 6)
Filtration & Separation     Full-text available via subscription   (Followers: 5)
Finite Fields and Their Applications     Full-text available via subscription   (Followers: 4)
Fire Science Reviews     Open Access   (Followers: 6)
Flexible Services and Manufacturing Journal     Hybrid Journal   (Followers: 1)
Flow, Turbulence and Combustion     Hybrid Journal   (Followers: 25)
Fluid Dynamics     Hybrid Journal   (Followers: 14)
Fluid Dynamics Research     Full-text available via subscription   (Followers: 11)
Fluid Phase Equilibria     Hybrid Journal   (Followers: 4)
Focus on Catalysts     Full-text available via subscription  
Focus on Pigments     Full-text available via subscription   (Followers: 4)
Focus on Powder Coatings     Full-text available via subscription   (Followers: 5)
Focus on Surfactants     Full-text available via subscription   (Followers: 4)
Food Engineering Reviews     Hybrid Journal   (Followers: 3)
Food Science and Technology     Open Access   (Followers: 4)
Formación Universitaria     Open Access   (Followers: 4)
FORMakademisk     Open Access  
Formal Methods in System Design     Hybrid Journal   (Followers: 7)
Forschung     Hybrid Journal   (Followers: 1)
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   (Followers: 1)
Frontiers in Energy     Hybrid Journal   (Followers: 4)
Frontiers in Geotechnical Engineering     Open Access   (Followers: 3)
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: 6)
Fuel Cells     Hybrid Journal   (Followers: 6)
Fuel Cells Bulletin     Full-text available via subscription   (Followers: 5)
Fusion Engineering and Design     Hybrid Journal   (Followers: 10)
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: 9)
Geoscience and Remote Sensing, IEEE Transactions on     Hybrid Journal   (Followers: 164)
Geotechnical Testing Journal     Full-text available via subscription   (Followers: 10)
Géotechnique     Hybrid Journal   (Followers: 28)
Geothermics     Hybrid Journal   (Followers: 6)
Glass Technology - European Journal of Glass Science and Technology Part A     Full-text available via subscription   (Followers: 4)
Global Journal of Engineering Research     Full-text available via subscription  
Global Perspective on Engineering Management     Open Access   (Followers: 3)
GPS Solutions     Hybrid Journal   (Followers: 17)
Graphs and Combinatorics     Hybrid Journal   (Followers: 7)
Grass and Forage Science     Hybrid Journal   (Followers: 8)
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   (Followers: 3)
Handai Nanophotonics     Full-text available via subscription  
Handbook of Adhesives and Sealants     Full-text available via subscription   (Followers: 2)
Handbook of Sensors and Actuators     Full-text available via subscription   (Followers: 10)
Haptics, IEEE Transactions on     Hybrid Journal   (Followers: 3)
Heat Exchangers     Open Access   (Followers: 3)
Heat Transfer - Asian Research     Hybrid Journal   (Followers: 12)
Heat Transfer Engineering     Hybrid Journal   (Followers: 30)
Historical Records of Australian Science     Hybrid Journal   (Followers: 2)
Human Factors in Ergonomics & Manufacturing     Hybrid Journal   (Followers: 11)
IBM Journal of Research and Development     Hybrid Journal   (Followers: 18)
IEEE Antennas and Propagation Magazine     Hybrid Journal   (Followers: 82)
IEEE Antennas and Wireless Propagation Letters     Hybrid Journal   (Followers: 70)
IEEE Communications Magazine     Full-text available via subscription   (Followers: 85)
IEEE Engineering Management Review     Full-text available via subscription   (Followers: 41)
IEEE Geoscience and Remote Sensing Letters     Hybrid Journal   (Followers: 149)
IEEE Industry Applications Magazine     Full-text available via subscription   (Followers: 25)
IEEE Instrumentation & Measurement Magazine     Full-text available via subscription   (Followers: 65)
IEEE Journal of Biomedical and Health Informatics     Hybrid Journal   (Followers: 15)
IEEE Journal of Oceanic Engineering     Hybrid Journal   (Followers: 13)
IEEE Journal of Selected Topics in Quantum Electronics     Hybrid Journal   (Followers: 8)
IEEE Journal of Selected Topics in Signal Processing     Hybrid Journal   (Followers: 39)
IEEE Journal of Solid-State Circuits     Full-text available via subscription   (Followers: 22)
IEEE Journal on Selected Areas in Communications     Hybrid Journal   (Followers: 23)
IEEE Latin America Transactions     Full-text available via subscription   (Followers: 3)
IEEE Microwave and Wireless Components Letters     Hybrid Journal   (Followers: 22)
IEEE Microwave Magazine     Full-text available via subscription   (Followers: 38)
IEEE Potentials     Full-text available via subscription   (Followers: 29)
IEEE Signal Processing Letters     Hybrid Journal   (Followers: 44)
IEEE Spectrum     Full-text available via subscription   (Followers: 186)
IEEE Technology and Society Magazine     Full-text available via subscription   (Followers: 7)
IEEE Transactions on Advanced Packaging     Full-text available via subscription   (Followers: 7)
IEEE Transactions on Antennas and Propagation     Full-text available via subscription   (Followers: 61)
IEEE Transactions on Applied Superconductivity     Hybrid Journal   (Followers: 5)
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: 21)
IEEE Transactions on Components and Packaging Technologies     Full-text available via subscription   (Followers: 15)
IEEE Transactions on Control Systems Technology     Hybrid Journal   (Followers: 58)
IEEE Transactions on Education     Hybrid Journal   (Followers: 9)
IEEE Transactions on Electronics Packaging Manufacturing     Full-text available via subscription   (Followers: 21)
IEEE Transactions on Energy Conversion     Hybrid Journal   (Followers: 16)
IEEE Transactions on Engineering Management     Hybrid Journal   (Followers: 28)
IEEE Transactions on Evolutionary Computation     Hybrid Journal   (Followers: 9)
IEEE Transactions on Information Theory     Hybrid Journal   (Followers: 27)
IEEE Transactions on Instrumentation and Measurement     Hybrid Journal   (Followers: 61)
IEEE Transactions on Intelligent Transportation Systems     Hybrid Journal   (Followers: 8)
IEEE Transactions on Knowledge and Data Engineering     Hybrid Journal   (Followers: 33)
IEEE Transactions on Magnetics     Hybrid Journal   (Followers: 14)
IEEE Transactions on Microwave Theory and Techniques     Hybrid Journal   (Followers: 29)
IEEE Transactions on Nuclear Science     Hybrid Journal   (Followers: 10)
IEEE Transactions on Plasma Science     Hybrid Journal   (Followers: 10)
IEEE Transactions on Power Delivery     Hybrid Journal   (Followers: 18)
IEEE Transactions on Professional Communication     Hybrid Journal   (Followers: 9)
IEEE Transactions on Reliability     Hybrid Journal   (Followers: 39)
IEEE Transactions on Semiconductor Manufacturing     Hybrid Journal   (Followers: 6)
IEEE Transactions on Signal Processing     Hybrid Journal   (Followers: 75)
IEEE Transactions on Vehicular Technology     Hybrid Journal   (Followers: 4)
IEEE Vehicular Technology Magazine     Full-text available via subscription   (Followers: 7)
IEEE/ACM Transactions on Computational Biology and Bioinformatics     Hybrid Journal   (Followers: 17)
IERI Procedia     Open Access  
IET Circuits, Devices & Systems     Hybrid Journal   (Followers: 19)
IET Generation, Transmission & Distribution     Hybrid Journal   (Followers: 3)
IET Image Processing     Hybrid Journal   (Followers: 17)
IET Micro and Nano Letters     Hybrid Journal   (Followers: 6)
IET Microwaves, Antennas & Propagation     Hybrid Journal   (Followers: 32)

  First | 1 2 3 4 5 6 7 | Last

Journal Cover AIChE Journal
  [SJR: 1.122]   [H-I: 120]   [32 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  [1589 journals]
  • Dynamic Catalytic Adsorptive Desulfurization of Real Diesel over
           Ultra-Stable and Low-Cost Silica Gel supported TiO2
    • Authors: Xiaoling Ren; Zewei Liu, Lei Dong, Guang Miao, Neng Liao, Zhong Li, Jing Xiao
      Abstract: The work aims to develop dynamic ultra-deep catalytic adsorptive desulfurization of real diesel using ultra-stable and low-cost silica gel supported TiO2. A two-stage dynamic breakthrough model was built to describe the CADS process, varied with H/R ratio and O/S ratio. The desulfurization capacity reached 1.3 mg-S/g-A at the breakthrough concentration of 5 ppm-S. Various types of silica gel were screened as the substrate for TiO2, and the textural/acidic properties and CADS capacity were correlated in high relevancy. The effectiveness of diverse oxidants on CADS and the oxidation path were elucidated via combined experiment/simulation. Adsorption enthalpy derived from fitted isotherm data was calculated as 33.4 kJ/mol. The TiO2/silica gel-based sorbent demonstrated remarkable recyclability/stability in 10 cycles. This work provides an effective and economic route to eliminate the trace amount of stubborn sulfur compounds in low-sulfur diesel, which can be potentially implemented as the final polishing step for ultra-clean diesel production. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:44.823274-05:
      DOI: 10.1002/aic.16055
       
  • Towards a continuous synthesis of porous carbon xerogel beads
    • Authors: David Eskenazi; Patrick Kreit, Jean-Paul Pirard, Philippe Compère, Nathalie Job
      Abstract: A continuous process for producing porous carbon xerogel beads has been developed. It consists in injecting a pre-cured aqueous solution of resorcinol and formaldehyde on top of a column filled with hot oleic acid. The latter is pumped on the top of the column and fed at the bottom, generating an upward flow that can be adjusted to match the terminal velocity of the settling beads. Thus, the bead residence time in the column can be adjusted to match the gelation time, allowing the beads to solidify before reaching the bottom of the vessel. The obtained beads are subsequently dried and pyrolyzed.The developed experimental setup proved the continuous synthesis of porous carbon beads is possible. Nevertheless, the shaping process caused various texture changes of the porous carbon, which mainly yields macropores instead of micro and mesopores. This process also leads to the build-up of a denser skin around the beads. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:40.993442-05:
      DOI: 10.1002/aic.16056
       
  • Surface Nonuniformities in Latex Paints due to Evaporative Mechanisms
    • Authors: K.B. Sutton; C.B. Clemons, K.L. Kreider, J.P. Wilber, G.W. Young
      Abstract: A model is developed for predicting long-wavelength nonuniformities in the thickness of drying latex paint films. The model includes the effects of temperature, latex particle volume fraction, surface surfactant density, bulk surfactant density, and several material and environmental factors. After the model is simplified by applying the lubrication approximation, equations for spatially independent base state solutions are derived. The base state solutions describe a drying latex paint film of uniform thickness. The equations for the base states are solved numerically and a linear stability analysis is conducted. This analysis indicates that evaporation, slow surfactant kinetics, low initial surface tension, substrate permeability, and high initial latex particle volume fractions destabilize the uniform film, while fast surfactant kinetics, high initial surface tension, and high viscosity are stabilizing. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-14T10:35:33.285414-05:
      DOI: 10.1002/aic.16057
       
  • Multi-Dimensional Modeling of a Microfibrous Entrapped Cobalt Catalyst
           Fischer-Tropsch Reactor Bed
    • Authors: M. S. Challiwala; B. A. Wilhite, M. M. Ghouri, N. O. Elbashir
      Abstract: Thermal management of highly-exothermic Fischer-Tropsch-Synthesis has been a challenging bottleneck limiting the radial dimension of the Packed-Bed (PB) reactor tube to 1.5”-ID. In this work, a computational demonstration of a novel Microfibrous-Entrapped-Cobalt-Catalyst (MFECC) in mitigating hotspot formation has been evaluated. Specifically, a 2-D model was developed in COMSOL®, validated with experimental data and subsequently employed to demonstrate scale-up of the FTS bed from 0.59” – 4”ID. Significant hot-spot of 102.39 K in PB was reduced to 9.4 K in MFECC bed under gas-phase at 528.15 K and 2 MPa. Improvement in heat-transfer within the MFECC bed facilitates higher productivities at low space velocities (≥1000 1/h) corresponding to high CO-conversion (≥90%). Additionally, the MFECC reactor provides an 8-fold increase in the reactor ID at hotspots≤30 K with CO% conversions≥90%. This model was developed for a typical FTS cobalt-based catalyst where CO2 production is negligible. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-12T15:41:18.867483-05:
      DOI: 10.1002/aic.16053
       
  • Synthesis of Ni Nanoparticles with Controllable Magnetic Properties by
           Atmospheric Pressure Microplasma Assisted Process
    • Authors: Liangliang Lin; Sergey A. Starostin, R. Lavrijsen, Wei Zhang, Sirui Li, Volker Hessel
      Abstract: An atmospheric pressure microplasma technique is demonstrated for the gas phase synthesis of Ni nanoparticles by plasma-assisted nickelocene dissociation at different conditions. The dissociation process and the products are characterized by complementary analytical methods to establish the relationship between operational conditions and product properties. The innovation is to show proof-of-principle of a new synthesis route which offers access to less costly and less poisonous reactant, a higher quality product, and a simple, continuous and pre/post treatment-free manner with chance for fine-tuning “in-flight”. Results show that Ni nanoparticles with controllable magnetic properties are obtained, in which flexible adjustment of product properties can be achieved by tuning operational parameters. At the optimized condition only fcc Ni nanoparticles are formed, with saturation magnetization value of 44.4 mAm2/g. The upper limit of production rate for Ni nanoparticles is calculated as 4.65 × 10−3 g/h using a single plasma jet, but the process can be scaled-up through a microplasma array design. In addition, possible mechanisms for plasma-assisted nickelocene dissociation process are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-12T15:41:06.40549-05:0
      DOI: 10.1002/aic.16054
       
  • Issue Information
    • Abstract: Cover illustration. Some of the most important properties of foods such as the release of flavors, texture and nutrient availability after digestion, among others, reside in a multiscale microstructure that we cannot see. A) Cryo-SEM image of whipped cream showing air cells surrounded by small fat droplets; B) A porous particle of freeze-dried coffee viewed with a micro CT; C) Magnetic resonance image of an apple bruised on both sides. 10.1002/aic.16018
      PubDate: 2017-12-11T10:22:38.259241-05:
      DOI: 10.1002/aic.15896
       
  • Limiting Flux in Microfiltration of Colloidal Suspensions by Focusing on
           Hydrodynamic Forces in Viscous Sublayer
    • Authors: Ryo Makabe; Kazuki Akamatsu, Shin-ichi Nakao
      Abstract: Cross-flow microfiltration tests were performed on colloidal suspensions under turbulence conditions. By changing the particle diameter, flow rate, and channel height in the membrane housing to measure limiting fluxes, the influence of each parameter on the limiting flux was assessed from the viewpoint of hydrodynamic forces exerted on a particle in the viscous sublayer. In analyzing all the data taken, we found that the particle Reynolds number calculated from the limiting flux is proportional to the 1.5-power of that calculated from the flow rate at the boundary between the viscous sublayer and the intermediate layer. This fact indicates that the limiting flux can be determined in situations where the drag force exerted by the flux is balanced by the lift force in the viscous sublayer. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:55.882106-05:
      DOI: 10.1002/aic.16050
       
  • Model fitting of sorption kinetics data: Rectification of misapplications
           overlooked
    • Authors: Yifeng Huang; Muhammad U. Farooq, Shuixiu Lai, Panida Sampranpiboon, Xiaodong Wang, Wei Huang, Xianshe Feng
      Abstract: When the model fitting of sorption kinetics data was carried out using linearized pseudo second order rate equations based on constant Qe corresponding to equilibrium sorption, the instantaneous driving force for sorption was underestimated, resulting in an erroneous overestimation of the rate constant. To resolve the issue, a rectification of the model fitting was proposed by accounting for the concentration dependence of Qe in the model equation based on the fact that Qe in the equation represents the sorption capacity at that instant as sorption proceeded with time. The rectified approach was validated with experimental data for various sorption systems reported in the literature. It was shown that the rectification yielded true sorption rate constant that characterizes the relationship between sorption rate and solute concentration, thereby resolving the issues associated with the original approach where the specific rate constant was found to depend on solute concentration and sorption time. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:51.887542-05:
      DOI: 10.1002/aic.16051
       
  • Heat Transfer Characteristics of Polymer Hollow Fiber Heat Exchanger for
           Vaporization Application
    • Authors: Jun Liu; Hong Guo, Xingxing Zhi, Lei Han, Kai Xu, Hailei Li, Baoan Li
      Abstract: The heat transfer characteristics of polymer hollow fiber heat exchanger were investigated by analysing the heat transfer coefficient (HTC) and the heat transfer resistance (HTR) distributions of both the lumen side and the shell side. The influences of the fiber wall thickness and the polymer thermal conductivity on the heat transfer performance were studied numerically based on the experimental validated simulation model. It is found that the original overall HTC value is below 1032 W/m2·K and the HTR is focus on the fiber wall. However, if enhancing the polymer thermal conductivity to be higher than 1.0 W/m·K and/or lowering the fiber wall thickness to be less than 0.1 mm, the overall HTC could be improved to over 2000 W/m2·K, which indicates that the fiber wall HTR is no longer the limiting factor of the polymer hollow fiber heat exchanger applications. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:10:37.500975-05:
      DOI: 10.1002/aic.16049
       
  • Mass Transfer Coefficient of Tubular Ultrafiltration Membranes under
           High-Flux Conditions
    • Authors: Kazuki Akamatsu; Keita Ishizaki, Shotaro Yoshinaga, Shin-ichi Nakao
      Abstract: The effect of suction flow on the mass transfer coefficient of tubular ultrafiltration membranes, in particular that under a high flux condition, was studied. We pointed out that Nsh is proportional to NRe 0.875 NSc 0.25 under turbulent conditions, and that the proportional constant, b, exceeds 0.023 when the effect of suction flow is not negligible. We conducted the velocity variation method using ultrafiltration membranes with MWCOs of 20k and 100k and dextrans having molecular weights of 40,000 and 70,000 at the conditions where NRe exceeded 3.6 × 103. We demonstrated that the effect of suction flow includes not only flux but also the diffusion coefficient of solute, and that the ratio of the flux to the diffusion coefficient, expressed as NPew, is an important index. Finally, we concluded that b = 0.023 when NPew is smaller than 2.23 × 103, giving the Deissler equation itself, and that b=2.04×10-6×NPew1.21 when NPew exceeds 2.23 × 103. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-08T13:05:23.128217-05:
      DOI: 10.1002/aic.16052
       
  • A Full-condition Monitoring Method for Nonstationary Dynamic Chemical
           Processes with Cointegration and Slow Feature Analysis
    • Authors: Chunhui Zhao; Biao Huang
      Abstract: Chemical processes are in general subject to time variant conditions because of load changes, product grade transitions, or other causes, resulting in typical nonstationary dynamic characteristic. It is of a considerable challenge for process monitoring to consider all possible operation conditions simultaneously including multifarious steady states and dynamic switchings. In the present work, a novel full-condition monitoring strategy is proposed based on both cointegration analysis (CA) and slow feature analysis (SFA) with the following considerations: (1) Despite that the operation conditions may vary over time, they may follow certain equilibrium relations that extend beyond the current time; (2) there may exist certain dynamic relations that stay invariant under normal process operation despite process may operate at different operating conditions. To monitor both equilibrium and dynamic relations, in the proposed method, nonstationary variables are separated from stationary variables first. Then by CA and SFA, the long-term equilibrium relation is distinguished from the specific relation held by the current conditions from both static and dynamic aspects. Various monitoring statistics are designed with clear physical interpretation. It can distinguish between the changes of operation conditions and real faults by checking deviations from equilibrium relation and deviations from the specific relation. Case study on a chemical industrial scale multiphase flow experimental rig shows the validity of the proposed full-condition monitoring method. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-06T15:25:32.357672-05:
      DOI: 10.1002/aic.16048
       
  • Combined Effects of Soot Load and Catalyst Activity on the Regeneration
           Dynamics of Catalytic Diesel Particulate Filters
    • Authors: Valeria Di Sarli; Almerinda Di Benedetto
      Abstract: The combined effects of soot load and catalyst activity on the regeneration dynamics of a catalytic diesel particulate filter have been investigated through transient CFD-based simulations of soot combustion in a single-channel configuration. The soot load was changed by varying the amount of soot accumulated as cake layer, while keeping the amount of soot trapped inside the catalytic wall constant.Substantially uniform soot combustion that allows reasonably fast regeneration of the filter under controlled temperature conditions has been simulated only in the absence of cake and at relatively low catalyst activity. Conversely, in the presence of cake, numerical predictions have shown that, regardless of both soot load and catalyst activity, fast regeneration always occurs by propagation of sharp reaction fronts that result in high temperature rises.These findings highlight the importance of avoiding the cake formation, while properly optimizing the catalyst activity, to conduct an effective regeneration of catalytic filters. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-05T07:55:41.670631-05:
      DOI: 10.1002/aic.16047
       
  • Influence of Mixing Performance on Polymerization of Acrylamide in
           Capillary Microreactors
    • Authors: Yang Song; Minjing Shang, Guangxiao Li, Luo Zheng-Hong, Yuanhai Su
      Abstract: Non-living free radical polymerization of acrylamide was chosen as a model reaction to investigate the effect of mixing performance on the polymerization in capillary microreactors. The polymerization rate was enhanced by increasing the volumetric flow rate and the reaction temperature at a constant residence time. However, higher temperatures led to lower Mn and larger PDI. The reaction mixture viscosity increased significantly during the polymerization. Both diffusion and dispersion coefficients were calculated in order to evaluate the mixing performance in microreactors. The capillary microreactor with a larger inner diameter led to higher monomer conversions, lower Mn and larger PDI compared to the capillary microreactor with a smaller inner diameter, which could be explained through a heat balance analysis for the polymerization and the dispersion effect. Moreover, it was found that the addition of a pre-mixing stage minimized the effect of insufficient mixing between the initiators and the monomers on the polymerization. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:31:21.040339-05:
      DOI: 10.1002/aic.16046
       
  • Multilevel Monte Carlo Applied to Chemical Engineering Systems Subject to
           Uncertainty
    • Authors: Grigoriy Kimaev; Luis A. Ricardez-Sandoval
      Abstract: The aim of this study is to evaluate the performance of Multilevel Monte Carlo (MLMC) sampling technique for uncertainty quantification in chemical engineering systems. Three systems (a mixing tank, a wastewater treatment plant and a ternary distillation column, all subject to uncertainty) were considered. The expected values of the systems' observables were estimated using MLMC, Power Series and Polynomial Chaos expansions, and standard Monte Carlo (MC) sampling. The MLMC technique achieved results of significantly greater accuracy than other methods at a lower computational cost than standard MC. This study highlights the nuances of adapting the MLMC technique to chemical engineering systems and the advantages of using MLMC for uncertainty quantification. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:31:11.300659-05:
      DOI: 10.1002/aic.16045
       
  • Simulation of Gas Separation Using Partial Element Stage Cut Modeling of
           Hollow Fiber Membrane Modules
    • Authors: Sina Gilassi; Seyed Mohammad Taghavi, Denis Rodrigue, Serge Kaliaguine
      Abstract: A mathematical model is developed to simulate a gas separation process using a hollow fiber membrane module. In particular, a new numerical technique is introduced based on flash calculation. Such analysis allows identifying the required membrane properties needed to reach module performance of interest. This model is validated for six different gas separation cases taken from literature. Then, the validated model is used to investigate the effect of O2 and N2 permeances on O2 recovery and O2 mole fraction in the permeate stream. A realistic two-stage air enrichment process is also proposed for O2 production using an industrial module with different fibers numbers. Moreover, this model is used to simulate a natural gas purification process using a single unit to determine the required membrane separation area and CH4 loss. Finally, a two-stage process is proposed to equally enhance CH4 retentate mole fraction and decrease CH4 loss. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-04T10:30:41.921538-05:
      DOI: 10.1002/aic.16044
       
  • Extending the Range of COSMO-SAC to High Temperatures and High Pressures
    • Authors: Christian L. Silveira; Stanley I. Sandler
      Abstract: In this paper we extend the range of the predictive Gibbs energy of solvation model, COSMO-SAC, to large ranges of density, pressure and temperature for very nonideal mixtures by combining it with an equation of state using the Wong-Sandler mixing rule. We compare the accuracy of isothermal vapor-liquid equilibria (VLE) calculations based on using the predictive COSMO-SAC model and separately the correlative NRTL model, each combined with three different forms of the Peng-Robinson equation of state (PREOS). All the models considered require the value of the EOS mixing rule binary parameter kij. The NRTL model also requires three other parameters obtained from correlation low pressure VLE data. We show that the PRSV + COSMO-SAC model, with its one adjustable parameter obtained from low temperature data leads good predictions at much higher temperatures and pressures. This article is protected by copyright. All rights reserved.
      PubDate: 2017-12-01T11:06:26.182402-05:
      DOI: 10.1002/aic.16043
       
  • Enhanced CO2 Separation Performance for Tertiary Amine-silica Membranes
           via Thermally Induced Local Liberation of CH3Cl
    • Authors: Liang Yu; Masakoto Kanezashi, Hiroki Nagasawa, Norihiro Moriyama, Henji Ito, Toshinori Tsuru
      Abstract: A facile method for the fabrication of amine-silica membranes with enhanced CO2 separation performance was proposed via the thermally induced liberation of small molecules from quaternary ammonium salt. Quaternary ammonium-silica (QA-SiO1.5) xerogel powders/films were fabricated via sol-gel processing and their thermal stability was systematically studied using TG-MS, FTIR, EDS, and PALS analysis. CO2 sorption performances of QA-SiO1.5 derived xerogel powders were quantitatively compared after assigning their relevant parameters to a dual-mode sorption model. The gas permeation performances of membranes derived from QA-SiO1.5 were evaluated in terms of kinetic diameter and temperature dependence of gas permeance, and activation energy (Ep) required for gas permeation. The results indicate that liberation of the CH3Cl molecules from these membranes significantly improved both CO2 permeation and CO2/N2 separation capabilities. Therefore, the present study provides insight that should be useful in the development of high-performance CO2 separation membranes via the effect of the thermally induced liberation of small molecules. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:40:55.024476-05:
      DOI: 10.1002/aic.16040
       
  • Stem Cell Biomanufacturing under Uncertainty: A Case Study in Optimizing
           Red Blood Cell Production
    • Authors: Ruth Misener; Mark C. Allenby, María Fuentes-Garí, Karan Gupta, Thomas Wiggins, Nicki Panoskaltsis, Efstratios N. Pistikopoulos, Athanasios Mantalaris
      Abstract: As breakthrough cellular therapy discoveries are translated into reliable, commercializable applications, effective stem cell biomanufacturing requires systematically developing and optimizing bioprocess design and operation. This manuscript proposes a rigorous computational framework for stem cell biomanufacturing under uncertainty. Our mathematical tool kit incorporates: high-fidelity modeling; single- and multivariate sensitivity analysis; global topological superstructure optimization; robust optimization. We quantitatively demonstrate the advantages of the proposed bioprocess optimization framework using, as a case study, a dual hollow fiber bioreactor producing red blood cells from progenitor cells. The optimization phase reduces the cost by a factor of 4 and the price of insuring process performance against uncertainty is approximately 15% over the nominal optimal solution. Mathematical modeling and optimization can guide decision making; we quantitatively evaluate the possible commercial impact of this cellular therapy using the disruptive technology paradigm. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:40:33.501778-05:
      DOI: 10.1002/aic.16042
       
  • Hydrodynamics in a Jet Bubbling Reactor: Experimental Research and
           Mathematical Modeling
    • Authors: Zhengliang Huang; Haotong Wang, Yun Shuai, Tianqi Guo, Musango Lungu, Yao Yang, Jingdai Wang, Yongrong Yang
      Abstract: The radial distribution of liquid velocity in the axial direction of a jet bubbling reactor has been measured by experimentation. Three different typical flow structures controlled by liquid jet, gas bubbling and liquid jet coupled with bubbling are observed. A tank in series model is established on this basis. Calculated values in each region are in good agreement with measured values in jet, bubbling and wall effect controlled areas. Axial flow rate, radial exchange rate and jet controlled volume η are analyzed from energy input aspect under different ug and uj. Simulation results indicate that under the synergetic action of the liquid jet and gas bubbling effect, jet controlled area exhibits a “spindle” structure, and its size decreases with the increase of ug. When gas input power occupies about 67% of total energy consumption, the best synergy of liquid jet and gas bubbling is obtained. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-28T10:35:36.521727-05:
      DOI: 10.1002/aic.16041
       
  • An Innovative Unit Operation of Particle Separation/Classification by
           Irradiating Low-Frequency Ultrasound into Water
    • Authors: Hiroya Muramatsu; Takayuki Saito
      Abstract: By irradiating kHz-band ultrasound, submillimeter- or millimeter-size particles that were dispersed in water with dissolved gases flocculated into a spherically flocculated particle swarm (SFPS). Acoustic cavitation-oriented bubbles caused by the irradiation played essential roles in the formation of the SFPS. Unprecedented and promising phenomena were observed: the particles were separated based on their diameters through the precise control of the ultrasound irradiation, and the SFPS was easily manipulated by using a motion-controlled stick. We discuss the relationship between the sound-pressure profiles and the manipulable range of the SFPS; i.e., the effectively manipulable range was limited by the sound-pressure profile. By means of manipulation control, we demonstrate the particle classification by particle diameters. On the basis of these findings, we propose an example of a practical application of this technique. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:40.100345-05:
      DOI: 10.1002/aic.16039
       
  • Numerical and Experimental Evaluation of Heat Transfer in Helically
           Corrugated Tubes
    • Authors: David J. Van Cauwenberge; Jens N. Dedeyne, Jens Floré, Kevin M. Van Geem, Guy B. Marin
      Abstract: The enhancement of convective heat transfer in single-phase heat transfer through the use of helicoidally corrugated tubes has been studied numerically. By comparing the large eddy simulation (LES) results with detailed Stereo-PIV and Liquid Crystal Thermography measurements obtained at the von Karman Institute for Fluid Dynamics (VKI), a validated numerical framework was obtained. Heat transfer enhancements of 83-119% were seen, at the cost of pressure losses that were approximately 5.6 to 6.7 times higher than for a bare tube. In order to extrapolate the results to industrial Reynolds numbers at which experimental data is scarce, the simulation data was used to develop an improved near-wall Reynolds stress transport model (RSTM) that more accurately describes the heat flux vector. Comparison of both global and local flow characteristics at different Reynolds numbers confirms that the approach allows more accurate predictions over a wider range of design and operating parameters than using two-equation turbulence models, while the computational cost is still significantly lower than LES. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:37.154999-05:
      DOI: 10.1002/aic.16038
       
  • Catalytic Partial Oxidation of CH4 over Bimetallic Ni-Re/Al2O3: Kinetic
           determination for Application in Microreactor
    • Authors: Kuson Bawornruttanaboonya; Navadol Laosiripojana, Arun S. Mujumdar, Sakamon Devahastin
      Abstract: The activity of a novel Ni-Re/Al2O3 catalyst toward partial oxidation of methane was investigated in comparison with a precious-metal Rh/Al2O3 catalyst. Reactions involving CH4/O2/Ar, CH4/H2O/Ar, CH4/CO2/Ar, CO/O2/Ar and H2/O2/Ar were performed to determine the kinetic expressions based on indirect partial oxidation scheme. A mathematical model comprising of Ergun equation as well as mass and energy balances with lumped indirect partial oxidation network was applied to obtain the kinetic parameters and then used to predict the reactant and product concentrations as well as temperature profiles within a fixed-bed microreactor. H2 and CO production as well as H2/CO2 and CO/CO2 ratios from the reaction over Ni-Re/Al2O3 catalyst were higher than those over Rh/Al2O3 catalyst. Simulation revealed that much smoother temperature profiles along the microreactor length were obtained when using Ni-Re/Al2O3 catalyst. Steep hot-spot temperature gradients, particularly at the entrance of the reactor, were, on the other hand, noted when using Rh/Al2O3 catalyst. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-24T10:40:22.472597-05:
      DOI: 10.1002/aic.16037
       
  • Magnetic Resonance Imaging of Gas-Solid Fluidization with Liquid Bridging
    • Authors: C. M. Boyce; A. Penn, K. P. Pruessmann, C. R. Müller
      Abstract: Magnetic resonance imaging is used to generate snapshots of particle concentration and velocity fields in gas-solid fluidized beds into which small amounts of liquid are injected. Three regimes of bed behavior (stationary, channeling and bubbling) are mapped based on superficial velocity and liquid loading. Images are analyzed to determine quantitatively the number of bubbles, the bubble diameter, bed height and the distribution of particle speeds under different wetting conditions. The cohesion and dissipation provided by liquid bridges cause an increase in the minimum fluidization velocity and a decrease in the number of bubbles and fast particles in the bed. Changes in liquid loading alter hydrodynamics to a greater extent than changes in surface tension or viscosity. Keeping U/Umf at a constant value of 1.5 produced fairly similar hydrodynamics across different wetting conditions. The detailed results presented provide an important dataset for assessment of the validity of assumptions in computational models. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:06:04.060573-05:
      DOI: 10.1002/aic.16036
       
  • Analysis of North-American Tight Oil Production
    • Authors: Raul Velascoa; Palash Panja, Manas Pathak, Milind Deo
      Abstract: North-American tight oil production has been on the rise due to the introduction of new drilling and hydraulic fracturing technologies. Such advances have dramatically changed the conventional understanding of the hydrocarbon recovery process. A dimensionless study of tight oil production across the United Sates in plays such as the Bakken, Niobrara, Eagle Ford, Woodford, Bone Spring, and Wolfcamp shed light on some of these recovery processes. Production from any well, regardless of geologic attributes and operating conditions, fits into a universal curve during its initial productive period. Subsequently, production becomes a strong function of hydrocarbon thermodynamics and multiphase flow. Results from this analysis help rank important parameters that affect oil recovery in terms of how wells are operated and the reservoir's intrinsic geological and fluid properties. Furthermore, production results are combined with a simple dimensionless economic analysis to determine optimal fracture configurations independent of oil price environment. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:00:56.000202-05:
      DOI: 10.1002/aic.16034
       
  • Simulation and Modeling of Segregating Rods in Quasi-2D Bounded Heap Flow
    • Authors: Yongzhi Zhao; Hongyi Xiao, Paul B. Umbanhowar, Richard M. Lueptow
      Abstract: Many products in the chemical and agricultural industries are pelletized in the form of rod-like particles that often have different aspect ratios. However, the flow, mixing, and segregation of non-spherical particles such as rod-like particles are poorly understood. Here, we use the discrete element method (DEM) utilizing super-ellipsoid particles to simulate the flow and segregation of rod-like particles differing in length but with the same diameter in a quasi-2D one-sided bounded heap. The DEM simulations accurately reproduce the segregation of size bidisperse rod-like particles in a bounded heap based on comparison with experiments. Rod-like particles orient themselves along the direction of flow, though bounding walls influence the orientation of the smaller aspect ratio particles. The flow kinematics and segregation of bidisperse rods having identical diameters but different lengths are similar to spherical particles. The segregation velocity of one rod species relative to the mean velocity depends linearly on the concentration of the other species, the shear rate, and a parameter based on the relative lengths of the rods. A continuum model developed for spherical particles that includes advection, diffusion, and segregation effects accurately predicts the segregation of rods in the flowing layer for a range of physical control parameters and particle species concentrations. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-21T10:00:31.548838-05:
      DOI: 10.1002/aic.16035
       
  • Robust Stabilization of a Two-Stage Continuous Anaerobic Bioreactor System
    • Authors: Zhaoyang Duan; Costas Kravaris
      Abstract: This paper studies the problem of stabilizing a two-stage continuous bioreactor system. A simple dynamic model of the system is first introduced based on a detailed mass balance model, and then used to derive a constant-yield controller to stabilize the system at given design steady state conditions. Using Lyapunov stability analysis, this control law is proved to guarantee stability of the closed loop system over the entire positive orthant. Simulation results show the successful performance of the controller. The control law is proved to be robust with respect to errors in the kinetic parameters and in the inlet feed concentration, in the sense of preserving its stability region. Performance of the control system can be enhanced if a feedforward measurement of the inlet feed concentration can be incorporated in the control law. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:55:41.235266-05:
      DOI: 10.1002/aic.16033
       
  • Mixed-Cation LiCa-LSX Zeolite with Minimum Lithium for Air Separation
    • Authors: Franklin E. Epiepang; Xiong Yang, Jianbo Li, Yingshu Liu, Ralph T. Yang
      Abstract: The aim of this work was to reduce/minimize Li in Li-LSX by replacing the 70% Li+ cations in Li-LSX that are bonded to the interior or inaccessible sites which are not used for adsorption. Thus, mixed-cation LiCa-LSX containing minimum lithium were prepared by exchanging small fractions of Li+ into Ca-LSX, followed by dehydration under mild conditions to avoid migration/equilibration of Li+ cations. Comparisons of adsorption isotherms of N2/O2 and heats of adsorption for the LiCa-LSX samples with that for pure-cation Li-LSX and Ca-LSX provided strong evidence that significant amounts of these Li+ cations indeed remained on the exposed sites (SIII). The mixed-cation LiCa-LSX samples were compared against the pure-cation Ca-LSX and Li-LSX based on their performance for oxygen production by PSA, via model simulation. The results showed that the mixed-cation LiCa-LSX samples yielded significantly higher O2 product productivities at the same product purity and recovery than their pure-cation precursor (Ca-LSX). This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:55:36.79446-05:0
      DOI: 10.1002/aic.16032
       
  • Modeling of Circulating Fluidized Beds systems for post-combustion CO2
           capture via Temperature Swing Adsorption
    • Authors: Stefano E. Zanco; Matteo Gazzani, Matteo C. Romano, Isabel Martínez, Marco Mazzotti
      Abstract: The technology of circulating uidized beds (CFB) is applied to temperature swing adsorption (TSA) processes for post-combustion CO2 capture employing a commercial zeolite sorbent. Steady state operation is simulated through a one-dimensional model, which combines binary adsorption with the CFB dynamics. Both single step and multi-step arrangements are investigated. Extensive sensitivity analyses are performed varying the operating conditions, in order to assess the inuence of the main operational parameters. The results reveal a neat superiority of multi-step configurations over the standard one, in terms of both separation performance and efficiency. Compared to fixed-bed TSA systems, CFB TSA features a high compactness degree. However, product purity levels are limited compared to the best performing fixed-bed processes, and heat management within the system appears to be a major issue. As regards energy efficiency, CFB systems place themselves in between the most established absorption-based technologies and the fixed-bed TSA. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:50:38.062582-05:
      DOI: 10.1002/aic.16029
       
  • Feedback control of proppant bank heights during hydraulic fracturing for
           enhanced productivity in shale formations
    • Authors: Prashanth Siddhamshetty; Joseph Sang-II Kwon, Shuai Liu, Peter P. Valkó
      Abstract: In hydraulic fracturing of shale formations, compared to conventional reservoirs, the fracturing fluid injected is of low-viscosity and hence during pumping the proppant settles significantly, forming a proppant bank. Motivated by this consideration, we initially develop a high-fidelity process model of hydraulic fracturing to describe the dominant proppant settling behavior during hydraulic fracturing. Second, a novel remeshing strategy is developed to handle the high computational requirement due to moving boundaries. Third, a section-based optimization method is employed to obtain key fracture design parameters for enhanced productivity in shale formations subject to given fracturing resources. Fourth, a reduced-order model is constructed to design a Kalman filter and to synthesize a real-time model-based feedback control system by explicitly taking into account actuator limitations, process safety and economic considerations. We demonstrate that the proposed control scheme can regulate the uniformity of proppant bank heights along the fracture at the end of pumping. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-14T10:50:30.307892-05:
      DOI: 10.1002/aic.16031
       
  • Optimal PID Controller Tuning using Stochastic Programming Techniques
    • Authors: Jose A. Renteria; Yankai Cao, Alexander W. Dowling, Victor M. Zavala
      Abstract: We argue that stochastic programming provides a powerful framework to tune and analyze the performance limits of controllers. In particular, stochastic programming formulations can be used to identify controller settings that remain robust across diverse scenarios (disturbances, set-points, and modeling errors) observed in real-time operations. We also discuss how to use historical data and sampling techniques to construct operational scenarios and inference analysis techniques to provide statistical guarantees on limiting controller performance. Under the proposed framework, it is also possible to use risk metrics to handle extreme (rare) events and stochastic dominance concepts to conduct systematic benchmarking studies. We provide numerical studies to illustrate the concepts and to demonstrate that modern modeling and local/global optimization tools can tackle large-scale applications. The proposed work also opens the door to data-based controller tuning strategies that can be implemented in real-time operations. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-11T09:50:21.698851-05:
      DOI: 10.1002/aic.16030
       
  • Optimal Operation of Batch Enantiomer Crystallization: From Ternary
           Diagrams to Predictive Control
    • Authors: Caio Felippe Curitiba Marcellos; Helen Durand, Joseph Sang-II Kwon, Amaro Gomes Barreto, Paulo Laranjeira da Cunha Lage, Maurício Bezerra de Souza, Argimiro Resende Secchi, Panagiotis D. Christofides
      Abstract: In this work, the modeling and control of batch crystallization for racemic compound forming systems is addressed in a systematic fashion. Specifically, a batch crystallization process is considered for which the initial solution has been pre-enriched in the desired enantiomer to enable crystallization of only the preferred enantiomer. A method for determining desired operating conditions (composition of the initial pre-enriched solution and temperature to which the mixture must be cooled for maximum yield) for the batch crystallizer based on a ternary diagram for the enantiomer mixture in a solvent is described. Subsequently, it is shown that the information obtained from the ternary diagram, such as the maximum yield attainable from the process due to thermodynamics, can be used to formulate constraints for an optimization-based control method to achieve desired product characteristics such as a desired yield. The proposed method is demonstrated for the batch crystallization of mandelic acid in a crystallizer with a fines trap that is seeded with crystals of the desired enantiomer. The process is controlled with an optimization-based controller to minimize the ratio of the mass of crystals obtained from nuclei to the mass obtained from seeds while maintaining the desired enantioseparation. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-10T11:05:24.444146-05:
      DOI: 10.1002/aic.16028
       
  • More Comprehensive 3D Modeling of Clay-like Material Drying
    • Authors: M. Heydari; K. Khalili, S. Y. Ahmadi-Brooghani
      Abstract: Drying process plays an important role in the manufacturing of many products such as ceramic, kitchenware and building materials, some of which have complex 3D geometry. To deal with many restrictions found in literatures, a 3D numerical approach was used to describe the drying process of a porous Clay-like material. The problem investigated involves highly coupled equations considering heat, mass and mechanical aspects. The model is validated through the comparison of experimental measurements with simulation result. Simulation results show that increasing the initial moisture content and reducing the initial temperature have the same privilege and without significant increase in drying time, it reduces slightly the amount of maximum stress but delays the occurrence time of maximum stress. The non-uniform heat expansion induced stresses are very small in comparison to non-uniform moisture shrinkage induced stresses and can be neglected in drying simulation. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-10T10:10:20.229176-05:
      DOI: 10.1002/aic.16027
       
  • Numerical Simulation on Flow Behaviour of Twin-liquid Films over a
           Vertical Plate with an Open Window
    • Authors: Hanguang Xie; Jianguang Hu, Gance Dai
      Abstract: A novel element for gas–liquid contact, a plate with rectangular windows was designed to enhance absorption process. Coexistence and interaction of wall-bounded films and confined free films named as “twin-liquid films” were observed on the plate. VOF method was used to simulate its flow behavior. Flow phenomena such as flow around a step-in, jet impingement, varicose waves, and sinuous waves were observed. Different from thin films flow on an unperforated plate, larger mean velocity, thinner film thickness, more intensive capillary waves, and stronger vorticity on the free surfaces were detected inside the window, and the disturbances could propagate over the whole plate. Three-dimensional simulation results generally agreed with our experimental observations and further demonstrated complex wavy structures both inside and outside the window. The results would broaden traditional knowledge of liquid films flow and clarify the mechanism of mass transfer intensification for the plate with windows. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:42.379766-05:
      DOI: 10.1002/aic.16021
       
  • Materials Genomics-Guided Ab Initio Screening of MOFs with Open Copper
           Sites for Acetylene Storage
    • Authors: Ce Zhang; Youshi Lan, Xiangyu Guo, Qingyuan Yang, Chongli Zhong
      Abstract: Discovering high-performance metal-organic frameworks (MOFs) with open metal sites has become an increasingly hot research topic in the field of safe storage and transportation of acetylene. Following the concept of Materials Genomics proposed recently, a database of 502 experimental MOFs was built by searching the structures deposited in the CSD with the dicopper paddle-wheel node Cu2(COO)4 as the characteristic materials gene. On the basis of the developed ab initio force field, a high-throughput computational screening was conducted to examine the property-performance relationships of MOFs containing Cu-OMS for C2H2 storage at ambient conditions. The optimal ranges of the structural and energetic features for the design of such MOFs were suggested. From our computational screening, three potentially promising MOFs were identified which exhibit a performance outperforming those MOFs reported experimentally so far with record high gravimetric C2H2 uptakes, both in the total and deliverable adsorption capacities. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:34.030147-05:
      DOI: 10.1002/aic.16025
       
  • DEM Study on the Discharge Characteristics of Lognormal Particle Size
           Distributions from a Conical Hopper
    • Authors: Ya Zhao; Shiliang Yang, Liangqi Zhang, Jia Wei Chew
      Abstract: This study employs the discrete element method (DEM) to investigate the impact of the widths of lognormal particle size distributions (PSDs) with the same mean particle diameter on hopper discharge behaviors, namely, discharge rate, particle velocities and size-segregation. Results reveal that (i) the hopper discharge rate decreases as PSD width increases; (ii) the mean discharge rates are constant with time, but the fluctuations increase as the PSD width increases; (iii) the overall size-segregation increases with PSD width; (iv) the overall mean particle diameters of the narrower PSDs do not exceed the initial mean of 5 mm, whereas that of wider ones do; (v) the relationship between PSD width and particle velocities is non-monotonic with no consistent trends; and (vi) no direct correlation exists between particle velocity and size-segregation. The results here provide valuable insights on the behavior of the prevalent polydisperse mixtures in hoppers. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T11:20:30.637498-05:
      DOI: 10.1002/aic.16026
       
  • Studies on Mild Catalytic Synthesis of Methyl Acrylate via One-Step Aldol
           Reaction
    • Authors: Gang Wang; Chidchon Sararuk, Zeng-xi Li, Chun-shan Li, Hui Wang, Suo-jiang Zhang
      Abstract: One-step catalytic synthesis of methyl acrylate from methyl acetate and trioxane, with 90.7% yield and 91.8% selectivity, was realized at 10°C-25°C. NMR analysis confirmed the ester enolization with generation of [i-Pr2EtN-H]+[TfO]- in the presence of i-Pr2EtN and Bu2BOTf, which was affected by solvent and base. The depolymerization of trioxane into formaldehyde was catalyzed by Bu2BOTf. The in-situ catalytic mechanism and efficiency of [i-Pr2EtN-H]+[TfO]- was determined and analyzed. Mechanism-based kinetic and thermodynamic studies were conducted for better understanding of this route. Also the primary process design and product separation simulation were carried out. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T01:15:52.329623-05:
      DOI: 10.1002/aic.16022
       
  • Synthesis of Ternary Distillation Process Structures Featuring Minimum
           Utility Cost Using the IDEAS Approach
    • Authors: Hiroshi Takase; Shinji Hasebe
      Abstract: A synthesis method for ternary distillation process structures is proposed on the basis of the infinite-dimensional state-space (IDEAS) approach. The proposed synthesis procedure consists of two steps. At the first step, the utility cost is minimized. The result of the first step contains many tiny flows among the modules because the number of flows is not included in the objective function. Then, at the second step, an evolutionary procedure for process simplification is executed. In this step, the weighted sum of flow rates is minimized recursively while updating the weights at each iteration. The practical process structure is finally determined from the result of the second simplification step. The developed synthesis procedure was applied to the separation problem of a ternary mixture consisting of benzene, toluene, and o-xylene. It demonstrated that the proposed procedure provides a process whose liquid composition profile is quite similar to that of a Petlyuk column. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-08T01:15:39.984478-05:
      DOI: 10.1002/aic.16023
       
  • A Comparative Kinetics Study of CO2 Absorption into Aqueous DEEA/MEA and
           DMEA/MEA Blended Solutions
    • Authors: Wusan Jiang; Xiayi Hu, Xiao Luo, Hongxia Gao, Zhiwu Liang, Bin Liu, Paitoon Tontiwachwuthikul
      Abstract: The kinetics of CO2 absorption into aqueous solutions of N,N-diethylethanolamine (DEEA), and N,N-dimethylethanolamine (DMEA), and their blends with monoethanolamine (MEA) have been studied in a stopped-flow apparatus. The kinetics experiments were carried out at the concentrations of DEEA and DMEA varying from 0.075 to 0.175 kmol/m3 respectively, and that of MEA ranging between 0.0075 and 0.0175 kmol/m3, over the temperature range of 293K to 313K. Two kinetics models are proposed to interpret the reaction in the blended amine systems and the results show that the model which incorporates the base-catalyzed hydration mechanism and termolecular mechanism resulted in a better prediction. Furthermore, the kinetics behaviors of CO2 absorption into two blended systems are comprehensively discussed according to their molecular structures. It can be concluded that the interaction between tertiary amines and primary amines as well as the alkyl chain length of tertiary amines have a significant influence on the kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-07T17:38:46.095241-05:
      DOI: 10.1002/aic.16024
       
  • Uncertainty-Conscious Methodology for Process Performance Assessment in
           Biopharmaceutical Drug Product Manufacturing
    • Authors: Gioele Casola; Christian Siegmund, Markus Mattern, Hirokazu Sugiyama
      Abstract: This work presents an uncertainty-conscious methodology for the assessment of process performance—e.g., run time—in the manufacturing of biopharmaceutical drug products. The methodology is presented as an activity model using the type 0 integrated definition (IDEF0) functional modelling method, which systematically interconnects information, tools, and activities. In executing the methodology, a hybrid stochastic–deterministic model that can reflect operational uncertainty in the assessment result is developed using Monte Carlo simulation. This model is used in a stochastic global sensitivity analysis to identify tasks that had large impacts on process performance under the existing operational uncertainty. Other factors are considered, such as the feasibility of process modification based on Good Manufacturing Practice, and tasks to be improved is identified as the overall output. In a case study on cleaning and sterilization processes, suggestions were produced that could reduce the mean total run time of the processes by up to 40%. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-06T17:21:56.05222-05:0
      DOI: 10.1002/aic.16020
       
  • A Branch and Bound Algorithm to Solve Large-Scale Multi-Stage Stochastic
           Programs with Endogenous Uncertainty
    • Authors: Brianna Christian; Selen Cremaschi
      Abstract: The growth in computation complexity of multistage stochastic programs (MSSPs) with problem size often prevents its application to real-world size problems. We present two variants of branch-and-bound algorithm, which reduce the resource requirements for the generation and solution of large-scale MSSPs with endogenous uncertainty. Both variants use Knapsack-problem based Decomposition Algorithm12 to generate feasible solutions and primal bounds. First variant (PH-KDA) uses a progressive hedging dual-bounding approach; the second (OSS-KDA) solves the MSSP removing all non-anticipativity constraints. Both variants were employed to solve several instances of the pharmaceutical clinical trial planning problem. The first iteration of both algorithms provide a feasible solution, and a primal bound and a dual bound for the problem. Although the dual-bounds of OSS-KDA were generally weaker than PH-KDA, they are generated considerably faster. For the seven-product case the OSS-KDA generated a solution with a gap of 9.92% in 115 CPU seconds. This article is protected by copyright. All rights reserved.
      PubDate: 2017-11-06T17:21:53.693542-05:
      DOI: 10.1002/aic.16019
       
  • Food engineering into the XXI century
    • Authors: José Miguel Aguilera
      PubDate: 2017-10-30T10:30:21.799741-05:
      DOI: 10.1002/aic.16018
       
  • Insight in Kinetics from Pre-edge Features using Time Resolved in situ XAS
    • Authors: N.V.R.A. Dharanipragada; Vladimir V. Galvita, Hilde Poelman, Lukas C. Buelens, Alessandro Longo, Guy B. Marin
      Abstract: The kinetics of reduction of a 10wt%Fe2O3-MgAl2O4 spinel were investigated using XRD and time resolved Fe-K QXANES. The Rietveld refinement of the XRD pattern showed the replacement of Al with Fe in the spinel structure and the formation of MgFeAlOx. The XANES pre-edge feature was employed to study the reduction kinetics during H2-TPR (Temperature Programmed Reduction) up to 730°C. About 55% of the Fe3+ in MgFeAlOx was reduced to Fe2+. A shrinking core model, which takes into account both solid-state diffusion via an oxygen diffusion coefficient, and gas-solid reaction through a reaction rate coefficient, was applied. The activation energy for chemical reaction showed a linear dependence on the conversion, increasing from 104 kJ/mol to 126 kJ/mol over the course of material reduction. The good accordance between the shrinking core model description and the experimental data indicates that XANES pre-edge features can be used to correlate changes in material structure and reaction kinetics. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-27T10:35:26.233322-05:
      DOI: 10.1002/aic.16017
       
  • Effect of Viscosity on Liquid Curtain Stability
    • Authors: Alireza Mohammad Karim; Wieslaw J. Suszynski, Lorraine F. Francis, Marcio S. Carvalho
      Abstract: The effect of viscosity on liquid curtain stability was explored by high-speed visualization. Measurements of the velocity within the curtain revealed the presence of a viscous boundary layer along the edge guides. The critical condition at the onset of curtain breakup was determined by identifying the flow rate below which the curtain broke for two different edge guide geometries: parallel and convergent. Curtain breakup was initiated by the expansion of a hole within the curtain. For low viscosity liquid, the measured hole retraction speed is independent of the viscosity and equal to the Taylor-Culick speed. For high viscosity liquids, the retraction speed is lower than the Taylor-Culick speed due to viscous forces that resist the flow. The results also show the effect of liquid viscosity on the curtain stability is a strong function of the edge guide design. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-24T11:06:24.441319-05:
      DOI: 10.1002/aic.16015
       
  • 3D-Foam-Structured Nitrogen-Doped Graphene-Ni Catalyst for Highly
           Efficient Nitrobenzene Reduction
    • Authors: Zhiyong Wang; Yuan Pu, Dan Wang, Jie Shi, Jie-Xin Wang, Jian-Feng Chen
      Abstract: We report the preparation of a porous 3D-foam-structured nitrogen-doped graphene-Ni (NG/NF) catalyst and the evaluation of its performance in the reduction of nitrobenzene (NB) through detailed studies of the kinetics. The NG/NF catalyst showed a significantly higher reaction rate than pure Ni foam (NF). Moreover, the separation of the 3D-foam-structured catalyst from the products was more convenient than that of NG powdered catalysts. The obtained kinetics data fit well to the Langmuir-Hinshelwood model, with an error ratio below 10%. Density functional theory (DFT) calculations indicated that the adsorption of sodium borohydride (NaBH4) on the NG/NF surface was stronger than that of NB, which strongly agreed with the kinetic parameters determined from the Langmuir-Hinshelwood model. The excellent catalytic efficiency of the 3D-foam-structured catalyst combined with the knowledge of the kinetics data make this catalyst promising for application in larger scale nitrobenzene reduction. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-24T11:05:10.257711-05:
      DOI: 10.1002/aic.16016
       
  • Highly Efficient Separation of Strongly Hydrophilic Structurally-Related
           Compounds by Hydrophobic Ionic Solutions
    • Authors: Qiwei Yang; Shaocong Guo, Xianxian Liu, Zhiguo Zhang, Zongbi Bao, Huabin Xing, Qilong Ren
      Abstract: The selective separation of strongly hydrophilic structurally-related compounds in aqueous solutions is a long-standing challenge due to a trade-off between separation selectivity and capacity. This work shows a new method to separate strongly hydrophilic structurally-related compounds through hydrophobic ionic solution-based liquid-liquid extraction, with L-ascorbic acid 2-glucoside (AA-2G) and L-ascorbic acid as model compounds. Extraordinary distribution coefficient, superb molecular selectivity, large extraction capacity and good recyclability without using strong acids and salts were all achieved, with a small consumption of phosphonium bromide ionic liquid and aprotic molecular diluent. The essence of this method is the successful combination of both strong hydrogen-bond basicity and good hydrophobicity along with significant preferential solvation phenomena of the constructed ionic solutions. Even if at a high feed concentration of 100 mg/ml, the purity of AA-2G could be greatly elevated from 50% to 96.2% with an ultrahigh yield of almost 100% after five-stage countercurrent extraction. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-22T05:55:31.803455-05:
      DOI: 10.1002/aic.16013
       
  • Joint Capacity Planning and Distribution Network Optimization of Coal
           Supply Chains under Uncertainty
    • Authors: Rui-Jie Zhou; Li-Juan Li
      Abstract: A two-stage stochastic integer programming model is developed to address the joint capacity planning and distribution network optimization of multi-echelon coal supply chains (CSCs) under uncertainty. The proposed model not only introduces the uses of compound real options in sequential capacity planning, but also considers uncertainty induced by both risks and ambiguities. Both strategic decisions (i.e., facility locations and initial investment, service assignment across the entire CSC, and option holding status) and scenario-based operational decisions (i.e., facility operations and capacity expansions, outsourcing policy, and transportation and inventory strategies) can be simultaneously determined using the model. By exploiting the nested decomposable structure of the model, we develop a new distributed parallel optimization algorithm based on non-convex generalized Bender decomposition and Lagrangean relaxation to mitigate the computation resource limitation. One of the main CSCs in China is studied to demonstrate the applicability of the proposed model and the performance of the algorithm. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-22T05:55:25.758985-05:
      DOI: 10.1002/aic.16012
       
  • Enhancing CO2 Absorption Efficiency using a Novel PTFE Hollow Fiber
           Membrane Contactor at Elevated Pressure
    • Authors: Fushan Wang; Guodong Kang, Dandan Liu, Meng Li, Yiming Cao
      Abstract: The internal structure design of membrane module is very important for gas removal performance using membrane contactor via physical absorption. In this study, a novel membrane contactor developed by weaving polytetrafluoroethylene (PTFE) hollow fibers was applied to remove CO2 from 60% N2 + 40% CO2 mixture (with CO2 concentration similar to that of biogas) at elevated pressure (0.8 MPa) using water as absorbent. Compared with the conventional module with randomly packed straight fibers, the module with woven PTFE fibers exhibited much better CO2 absorption performance. The weaving configuration facilitated the meandering flow or Dean vortices and renewing speed of water around hollow fibers. Meanwhile, the undesired influences such as channeling and bypassing were also eliminated. Consequently, the mass transfer of liquid phase was greatly improved and the CO2 removal efficiency was significantly enhanced. The effects of operation pressure, module arrangement, feed gas and water flow rate on CO2 removal were systematically investigated as well. The overall mass transfer coefficient (KOV) varied from 1.96 × 10−5 to 4.39 × 10−5 m/s (the volumetric mass transfer coefficient KLa = 0.034 – 0.075 s−1) under the experimental conditions. The CO2 removal performance of novel woven fiber membrane contactor matched well with the simulation results. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-22T05:50:24.492818-05:
      DOI: 10.1002/aic.16014
       
  • Two-Step Continuous Production of Monodisperse Colloidal Ellipsoids at
           Rates of One Gram per Day
    • Authors: Joseph A. Ferrar; Leonid Pavlovsky, Yanliang Liu, Eric Viges, Michael J. Solomon
      Abstract: We report a two-step process for the continuous production of monodisperse polystyrene colloidal ellipsoids of aspect ratios up to 6.8 at rates that exceed 1.0 g per day, an improvement upon previously reported synthetic batch processing rates of nearly a factor of 20. This scale up is accomplished by continuous evaporative processing of a polymer solution into an elastomeric film embedded with colloidal spheres. Subsequently, the film is continuously elongated at a temperature that stretches the embedded spheres into ellipsoids. The method is used to deform initially 1.0 μm diameter spheres into ellipsoids of aspect ratio 1.27 ± 0.15, 3.31 ± 0.44, 3.91 ± 0.72, 4.14 ± 0.47, and 6.77 ± 1.01. The particle production rate reported here opens new possibilities for applications of monodisperse ellipsoids, such as self-assembly and optical characterization of complex crystalline unit cells, as well as rheological characterization of dilute gels and dense suspensions. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:06:30.057101-05:
      DOI: 10.1002/aic.16009
       
  • Liquid-Liquid Two-Phase Flow in Ultrasonic Microreactors: Cavitation,
           Emulsification and Mass Transfer Enhancement
    • Authors: Shuainan Zhao; Zhengya Dong, Chaoqun Yao, Zhenghui Wen, Guangwen Chen, Quan Yuan
      Abstract: The effects of ultrasound on the hydrodynamic and mass transfer behaviors of immiscible liquid-liquid two-phase flow were investigated in a domestic ultrasonic microreactor. Under ultrasonic irradiation, cavitation bubble was generated and underwent violent oscillation. Emulsification of immiscible phases was initiated by virtue of oscillating bubbles shuttling through the water/oil interface. The pressure drop was found to decrease with increasing ultrasound power, with a maximum decrement ratio of 12% obtained at power 30 W. The mass transfer behavior was characterized by extraction of Rhodamine B from water to 1-octanol. An enhancement factor of 1.3-2.2 on the overall mass transfer coefficient was achieved under sonication. The mass transfer performance was comparable to passive microreactor at similar energy dissipation rate (61-184 W/kg). The extraction equilibrium was reached under a total flow velocity 0.01 m/s and input power 20 W and 30 W, exhibiting its potential use in liquid-liquid extraction process. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:06:19.903927-05:
      DOI: 10.1002/aic.16010
       
  • Multivariable Model Predictive Control of a Novel Rapid Pressure Swing
           Adsorption System
    • Authors: Matthew D. Urich; Vemula Rama Rao, Mayuresh V. Kothare
      Abstract: A multivariable model predictive control (MPC) algorithm is developed for the control and operation of a rapid pressure swing adsorption (RPSA) based medical oxygen concentrator (MOC). The novelty of the approach is the use of all four step durations in the RPSA cycle as independent manipulated variables in a truly multivariable context. The RPSA has a complex, cyclic, nonlinear multivariable operation that requires feedback control, and MPC provides a suitable framework for controlling such a multivariable system. The multivariable MPC presented here uses a quadratic optimization program with integral action and a linear model identified using sub-space system identification techniques. The controller was designed and tested in simulation using a complex, highly coupled, nonlinear RPSA process model. The model was developed with the least restrictive assumptions compared to those reported in the literature, thereby providing a more realistic representation of the underlying physical phenomena. The resulting MPC effectively tracks set points, rejects realistic process disturbances and is shown to outperform conventional PID control. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:05:22.900109-05:
      DOI: 10.1002/aic.16011
       
  • Receding horizon optimal operation and control of a solar-thermal district
           heating system
    • Authors: Xiaodong Xu; Yuan Yuan, Stevan Dubljevic
      Abstract: This work focuses on the receding horizon optimal control for a solar-thermal district heating (STDH) system containing lumped parameter and distributed parameter subsystems. A common STDH system includes solar collector system, a short term energy storage tank and a district heating loop system with a secondary gas boiler system. The inclusion or exclusion of these components leads to different operational and working modes. Detailed system description and mathematical models are provided, and three working modes are introduced and in each mode several operations are demonstrated and addressed. Single-objective and multi-objective problems are formulated. Moreover, in the mode where gas boiler system is included to help addressing the district heating demand, the internal model based boundary servo-control approach is proposed and applied to obtain desired boiler water temperatures such that the expected district heating demand can be satisfied. Moreover, a boundary state observer is designed for the considered solar collector system. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:00:23.030221-05:
      DOI: 10.1002/aic.16007
       
  • Simulation on Hydrogen Storage Properties of Metal-Organic Frameworks
           Cu-BTC at 77K∼298K
    • Authors: Shumin Chen; Yumei Shi, Bo Gu
      Abstract: In recent years, many researchers have studied on the hydrogen storage properties of metal-organic frameworks (MOFs) by grand canonical Monte Carlo (GCMC) simulation. At present, the GCMC studies of Cu-BTC (BTC: benzene-1,3,5-tricarboxylate) which is a prototypical metal-organic framework mainly adopt the classical force fields, the simulation temperatures are mainly focus on 298K and 77K, and most researchers didn't consider the effects of quantum effects at low temperature. Therefore, we used the quantum effects to correct the classical force fields and the force fields with more accurate simulation results were used to simulate the hydrogen adsorption performances of Cu-BTC in the temperature range of 77K∼298K and the pressure range of 1∼8MPa at each temperature. The results show that the effects of quantum effects on the hydrogen storage of Cu-BTC cannot be neglected and the corrected Dreiding force field can simulate hydrogen adsorption performances of Cu-BTC more accurately at low temperature. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-19T11:00:19.409574-05:
      DOI: 10.1002/aic.16008
       
  • Low Reynolds number isotope transient kinetic modeling in isothermal
           differential tubular catalytic reactors
    • Authors: Masood Otarod; Ronald M. Supkowski
      Abstract: A novel method is presented for modeling steady state isotope transient kinetics of heterogeneous catalytic reactions when the flow regime is laminar and conversion is differential. It is based on a factorization theorem which is deduced from the observation that transport functions fluctuate radially in porous beds. Factorization separates the radial from axial and temporal coordinates of the flow rate and concentration functions. It is shown that in transient tracing with a differential conversion, the radial components of the transport functions in the material conservation equations can be integrated into constant parameters to be determined from experimental data. The method is in particular useful since the knowledge of the radial profile of velocity and other transport functions and parameters are not prerequisites for data correlation. The methodology was successfully applied to the adsorption of carbon monoxide in Boudouard reaction on an alumina supported palladium catalyst. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-16T01:15:28.033637-05:
      DOI: 10.1002/aic.16006
       
  • A Pore Network Study of Evaporation from the Surface of a Drying
           Non-Hygroscopic Porous Medium
    • Authors: Alireza Attari Moghaddam; Abdolreza Kharaghani, Evangelos Tsotsas, Marc Prat
      Abstract: The phenomena occurring at the surface of a porous medium during drying in the capillary regime are investigated by pore network simulations. The impact of the formation of wet and dry patches at the surface on the drying rate is studied. The simulations indicate an edge effect characterized by a noticeable variation of saturation in a thin layer adjacent to the porous surface. Also, the results indicate a significant non-local equilibrium effect at the surface. The simulation results are exploited to test Schlünder's classical model which offers a simple closure relationship between the evaporation rate and the degree of occupancy of the surface by the liquid. In addition to new insights into the surface phenomena, the results open up new prospects for improving the continuum models of the drying process. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-13T10:55:37.309147-05:
      DOI: 10.1002/aic.16004
       
  • DEM-PBM modeling of abrasion dominated ribbon breakage
    • Authors: Simone Loreti; Chuan-Yu Wu, Gavin Reynolds, Jonathan Seville
      Abstract: In dry granulation, fine cohesive powders are compacted into large multi-particle entities, i.e., briquettes, flakes or ribbons. The powder compaction is generally followed by milling, a size reduction process, which is crucial to obtain the desired granule size or properties. Abrasion and impact are two primary mechanisms of comminution in ribbon milling, but they are not completely understood. The aim of this paper was hence to investigate numerically the fragmentation process induced by abrasion during ribbon milling. The discrete element method (DEM) was employed to simulate abrasion tests, for which three-dimensional parallelepiped ribbons were generated using auto-adhesive elastic spheres. The fragmentation rate, and the fragments size and number were determined for various surface energies and abrasive velocities. The DEM results showed that the mass-equivalent fragment size distributions were bi-modal, similar to the experimental observations and the numerical results for impact-dominated ribbon milling reported in the literature. In addition, two quantities were determined from the DEM analysis, i.e. the number of large fragments and the fraction of fines, which was then integrated into the population balance models (PBM) so that a DEM-PBM multiscale modeling framework was developed to predict the granule size distribution during ribbon milling. The DEM-PBM results were compared with the experimental results reported in the literature, and a broad agreement was obtained, implying the proposed DEM-PBM can be used to analyse the ribbon milling behavior. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-13T10:55:31.869796-05:
      DOI: 10.1002/aic.16005
       
  • Improving mixing characteristics with a pitched tip in kneading elements
           in twin-screw extrusion
    • Authors: Yasuya Nakayama; Hiroki Takemitsu, Toshihisa Kajiwara, Koichi Kimura, Takahide Takeuchi, Hideki Tomiyama
      Abstract: In twin-screw extrusion, the geometry of a mixing element mainly determines the basic ow pattern, which eventually affects the mixing ability as well as the dispersive ability of the mixing element. We discuss the effects of geometrical modification, with both forward and backward pitched tips, of a conventional forwarding kneading discs element (FKD) in the pitched-tip kneading discs element (ptKD) on the ow pattern and mixing characteristics. Numerical simulations of fully-filled, non-isothermal polymer melt ow in the melt-mixing zone were performed, and the flow pattern structure and the tracer trajectories were investigated. The pitched tips largely affects the inter-disc fluid transport, which is mainly responsible for mixing. These changes in the local ow pattern are analyzed by the distribution of the strain-rate state. The distribution of the finite-time Lyapunov exponent reveals a large inhomogeneity of the mixing in FKD is suppressed both by the forward and backward tips. By the forward tips on FKD, the mixing ability is relatively suppressed compared to FKD, whereas for the backward tips on FKD, the mixing ability is enhanced while maintaining the same level of dispersion efficiency as FKD. From these results, the pitched tips on the conventional KD turns out to be effective at reducing the inhomogeneity of the mixing and tuning the overall mixing performance. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-13T10:46:06.039922-05:
      DOI: 10.1002/aic.16003
       
  • Chemical Hydrodynamics of a Downward Microbubble Flow for Intensification
           of Gas-Fed Bioreactors
    • Authors: Manizheh Ansari; D.E. Turney, R. Yakobov, D.V. Kalaga, S. Kleinbart, Sanjoy Banerjee, J.B. Joshi
      Abstract: Bioreactors are of interest for value-upgrading of stranded or waste industrial gases. Reactor intensification requires development of low cost bioreactors with fast gas-liquid mass transfer rate. Here we assess published reactor technology in comparison with a novel downward bubble flow created by a micro-jet array. Compared to known technology, the advanced design achieves higher volumetric gas transfer efficiency (kLa per power density) while operating at higher kLa. We measure the effect of four reactor heights (height-to-diameter ratios of 12, 9, 6 and 3) on the gas transfer coefficient kL, total interfacial area a, liquid residence time distribution, energy consumption, and turbulent hydrodynamics. Leading models for predicting kL and a are appraised with experimental data. The results show kL is governed by “entrance effects” due to Higbie penetration dominate at short distances below the micro-jet array, while turbulence dominates at intermediate distances, and finally terminal rise velocity dominates at large distances. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-13T10:45:25.454122-05:
      DOI: 10.1002/aic.16002
       
  • Pressure Drop through Platinized Titanium Porous Electrodes for
           Cerium-based Redox Flow Batteries
    • Authors: Luis F. Arenas; Carlos Ponce de León, Frank C. Walsh
      Abstract: The pressure drop, ΔP, across a redox flow battery is linked to pumping costs and energy efficiency, making fluid properties of electrodes important in scale-up. In this work, the ΔP at diverse platinized titanium electrodes in Ce-based redox flow batteries is reported as a function of mean linear electrolyte velocity measured in a rectangular channel flow cell. Darcy's friction factor and permeability vs. Reynolds number are calculated. Average permeability values are: 7.10 × 10−4 cm2 for Pt/Ti mesh, 4.45 × 10−4 cm2 for Pt/Ti plate + turbulence promoters, 1.67 × 10−5 cm2 for Pt/Ti micromesh, and 1.31 × 10−6 cm2 for Pt/Ti felt. The electrochemical volumetric mass transport coefficient, kmAe, is provided as a function of ΔP. In the flow-by configuration, Pt/Ti felt combines high kmAe values with a relatively high ΔP, followed by Pt/Ti micromesh. Pt/Ti mesh and Pt/Ti plate gave a lower ΔP but poorer electrochemical performance. Implications for cell design are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-12T11:30:36.188909-05:
      DOI: 10.1002/aic.16000
       
  • Modeling the Deposition of Fluorescent Whitening Agents (FWAs) on Cotton
           Fabrics
    • Authors: L. Bueno; C. Amador, S. Bakalis
      Abstract: The adsorption of two widely used Fluorescent Whitening Agents (FWAs) on un-brightened cotton fabrics has been investigated as a function of temperature, hardness of the wash liquor, initial concentration of FWA in solution and fabric to wash liquor ratio. Sorption efficiencies of FWAs have been studied using a UV spectrophotometry technique. A mechanistic model has been developed to describe the dissolution process of FWAs, convective mass transport into the fabrics, diffusion in the stagnant layer to the fabrics' surface and adsorption of FWAs on cotton fabrics. Dual porosity of the fabrics (inter-yarn and intra-yarn porosity) has been considered by allowing two different regions (outer and inner areas of the cotton fabrics) where FWAs molecules can diffusive and adsorb. Good agreement between experimental and predicted whiteness benefit by the proposed mathematical model has been observed for the range of variables considered. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-12T11:15:27.922426-05:
      DOI: 10.1002/aic.16001
       
  • Computer-Aided Design of Ionic Liquids as Solvents for Extractive
           Desulfurization
    • Authors: Zhen Song; Chenyue Zhang, Zhiwen Qi, Teng Zhou, Kai Sundmacher
      Abstract: Although ionic liquids (ILs) have been widely explored as solvents for extractive desulfurization (EDS) of fuel oils, systematic studying of the optimal design of ILs for this process is still scarce. In this work, the UNIFAC-IL model is extended first to describe the EDS system based on exhaustive experimental data. Then, based on the obtained UNIFAC-IL model and group contribution models for predicting the melting point and viscosity of ILs, a mixed-integer nonlinear programming (MINLP) problem is formulated for the purpose of computer-aided ionic liquid design (CAILD). The MINLP problem is solved to optimize the liquid-liquid extraction performance of ILs in a given multi-component model EDS system, under consideration of constraints regarding the IL structure, thermodynamic and physical properties. The top five IL candidates pre-identified from CAILD are further evaluated by means of process simulation using ASPEN Plus. Thereby, [C5MPy][C(CN)3] is identified as the most suitable solvent for extractive desulfurization. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:40:34.375093-05:
      DOI: 10.1002/aic.15994
       
  • Synergistic Effects of Sulfur Poisoning and Gas Diffusion on Polarization
           Loss in Anodes of Solid Oxide Fuel Cells
    • Authors: Yinghua Niu; Weiqiang Lv, Zhaohuan Wei, Weirong Huo, Weidong He
      Abstract: Poisoning effects of sulfur compounds on the performances of solid oxide fuel cells (SOFCs) are non-trivial. However, the synergistic effects of gas diffusion, adsorption, desorption and reaction in anodes are typically neglected. In this work, an analytical model is derived to quantitatively evaluate the poisoning effects of H2S. The results show that sulfur poisoning correlates closely with inefficient gas diffusion for small anode pore size, small porosity/tortuosity and low working temperatures. As compared with concentration polarization, H2S-diffusion-induced activation polarization in thin anodes with a large ε/τ is detrimental, especially for low-temperature operations with a high H2S concentration and a low current density. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:40:31.827109-05:
      DOI: 10.1002/aic.15997
       
  • The Promotion of Argon and Water Molecule on Direct Synthesis of H2O2 from
           H2 and O2
    • Authors: Yanhui Yi; Li Wang, Juan Yu, Changgong Meng, Jialiang Zhang, Hongchen Guo
      Abstract: Direct synthesis of hydrogen peroxide (H2O2) from H2 and O2 is an ideal route. H2/O2 plasma has a great potential for direct synthesis of high purity H2O2 without purification operations. However, low yield and high energy consumption limits the application of H2/O2 plasma in industry. This paper reports that gas state Ar and H2O molecule serving as molecular catalysts promoted the synthesis of H2O2 from H2/O2/Ar/H2O plasma dramatically: the H2O2 yield was enhanced by 244% and the energy consumption was reduced by 70.9%. Ar not only increased the electron density, but also selectively accelerated the dissociation of H2 towards the formation of •HO2, a key intermediate species in H2O2 synthesis. While H2O facilitated the formation of •HO2 radical and stabilized it by forming a HO2•H2O complex, resulting in enhancing the H2O2 production. This single molecular catalysis reduced the cost of H2O2 synthesis more than 50%. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:40:28.540728-05:
      DOI: 10.1002/aic.15999
       
  • Integrated Solvent and Process Design for Continuous Crystallization and
           Solvent Recycling using PC-SAFT
    • Authors: Jiayuan Wang; Richard Lakerveld
      Abstract: Solvent usage is a major source of environmental waste in pharmaceutical industry. The current paradigm shift towards continuous manufacturing in pharmaceutical industry has renewed the interest in continuous crystallization, which offers the prospect of easy solvent recycling. However, the selection of solvents for an integrated crystallization processes is nontrivial due to the likely trade-off between optimal solvent properties for crystallization and solvent separation and recycling. A systematic approach for the simultaneous optimization of process conditions and solvent selection for continuous crystallization including solvent recycling is presented. A unified PC-SAFT model framework is applied to predict thermodynamic properties related to solubility and vapor-liquid equilibrium, which is integrated with a process model. A continuous mapping procedure is adopted to solve the optimization problem effectively. A case study based on continuous anti-solvent crystallization of paracetamol with solvent separation via flash demonstrates the approach. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:40:21.501415-05:
      DOI: 10.1002/aic.15998
       
  • A Dynamic Game Theoretic Framework for Process Plant Competitive Upgrade
           and Production Planning
    • Authors: Philip Tominac; Vladimir Mahalec
      Abstract: A dynamic potential game theoretic production planning framework is presented in which production plants are treated as individual competing entities and competition occurs dynamically over a discrete finite time horizon. A modified Cournot oligopoly with sticky prices provides the basis for dynamic game theoretic competition in a multi-market nonlinear and nonconvex production planning model wherein market price adapts to a value that clears cumulative market supply. The framework is used to investigate a petrochemical refining scenario in which a single inefficient refiner faces elimination by its competitors; we demonstrate that there exist conditions under which the threatened refiner may upgrade itself in order to become competitive and escape the threat, or alternatively in which the threat of elimination will never be carried out and the refiner is effectively safe in the given market configuration. Globally optimal dynamic Nash equilibrium production trajectories are presented for each case. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:35:24.932878-05:
      DOI: 10.1002/aic.15995
       
  • A Thermodynamic Investigation of Adsorbate-Adsorbate Interactions of
           Carbon Dioxide on Nanostructured Carbons
    • Authors: Maxwell Murialdo; Channing C. Ahn, Brent Fultz
      Abstract: A thermodynamic study of carbon dioxide adsorption on a zeolite-templated carbon (ZTC), a superactivated carbon (MSC-30) and an activated carbon (CNS-201) was carried out at temperatures from 241 to 478 K and pressures up to 5.5•106 Pa. Excess adsorption isotherms were fitted with generalized Langmuir-type equations, allowing the isosteric heats of adsorption and adsorbed-phase heat capacities to be obtained as a function of absolute adsorption. On MSC-30, a superactivated carbon, the isosteric heat of carbon dioxide adsorption increases with occupancy from 19 to 21 kJ•mol−1, before decreasing at high loading. This increase is attributed to attractive adsorbate-adsorbate intermolecular interactions as evidenced by the slope and magnitude of the increase in isosteric heat and the adsorbed-phase heat capacities. An analysis of carbon dioxide adsorption on ZTC indicates a high degree of binding-site homogeneity. A generalized Law of Corresponding States analysis indicates lower carbon dioxide adsorption than expected. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-10T18:35:22.8165-05:00
      DOI: 10.1002/aic.15996
       
  • An interfacial curvature distribution model and phase inversion
    • Authors: A. Vikhansky
      Abstract: The state of the two-phase system is described by the interfacial curvature distribution. A phenomenological closure model is proposed for the exact (unclosed) equations. Parameters of the model are related to the existing correlations for drop size in stirred flows. If water is dispersed in oil, the curvature has a uni-modal distribution with a positive mode. When a control parameter, e.g., water volume fraction is increasing, the distribution becomes bi-modal with both negative and positive values. After a while, the phase inversion occurs, and the distribution becomes uni-modal with a negative mode. Going in the other direction the phase inversion happens at lower volume fraction of water, i.e., there is an ambivalent region, where both phases might be in the dispersed state. The model implies, that even if the conditions for phase inversion are met, there might be a significant delay before the new morphology is established. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-06T17:50:21.172204-05:
      DOI: 10.1002/aic.15992
       
  • Model Based Analysis of Lithium Batteries Considering Particle Size
           Distribution
    • Authors: E. R. Henquín; P. A. Aguirre
      Abstract: Performance of lithium ion batteries whose electrodes are composed of particles of different sizes is studied. Simplified model developed in 7 is extended and the simulations are compared with experiments from the literature so as to validate this new model. The differences in current density observed in particles of different sizes, which are in contact, depend on particle size and state of charge. Internal particle to particle discharge currents are observed during relaxation times. A parametric study of the applied current and particle sizes of electrodes is carried out to evaluate cell performance, with emphasis on cell voltage and final capacity measurement. The evolution of reaction rates on the surface of electrode particles and their corresponding states of charge are depicted. An analysis of relaxation times in terms of cell voltage, current density, equilibrium potentials, and overpotentials is included. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-05T04:20:21.195117-05:
      DOI: 10.1002/aic.15990
       
  • Packaging of Yield Stress Fluids: Flow Patterns
    • Authors: Fanny Rasschaert; Emeline Talansier, Didier Blésès, Maud Lambert, Albert Magnin
      Abstract: The packaging or filling of a container with a non-Newtonian fluid without quality failures is a current issue encountered at the final step of industrial product processes. In this work, the container filling of viscoplastic fluids is studied by using an experimental laboratory plant able to reproduce the industrial transitory packaging conditions. Firstly, a Newtonian validation was conducted in order to compare and to confirm our set-up results with available literature data. Secondly five flow patterns including dripping, jet buckling, mounding, planar filling and air entrainment were observed and characterized for the viscoplastic container filling. Most of them present different types of instabilities during the filling, except the planar filling, which seems to be ideal according to industrial specifications. A flow pattern distribution depending on relevant dimensionless numbers was developed. Finally, flow pattern transition criteria are determined highlighting the influence of rheological and process parameters on container filling. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-04T10:56:05.754901-05:
      DOI: 10.1002/aic.15989
       
  • Enhanced Solubility of Hydrogen and Carbon Monoxide in Propane- and
           Propylene-Expanded Liquids
    • Authors: Dupeng Liu; Raghunath V. Chaudhari, Bala Subramaniam
      Abstract: Conventional propylene hydroformylation occurs in a gas-expanded liquid phase. Reliable knowledge of the phase equilibria of such systems, including the solubilities of CO and H2 in propylene-expanded solvents, is essential for rational process design and development. Herein, we report the vapor-liquid equilibrium (VLE) data of the following ternary systems involving CO, H2, propane, propylene, toluene and NX-795 at temperatures from 70 to 90°C and pressures up to 1.5 MPa: propane/H2/toluene, propane/CO/toluene, propylene/H2/toluene, propylene/CO/toluene, propane/H2/NX-795, propane/CO/NX-795, propylene/H2/NX-795 and propylene/CO/NX-795. The solubilities of H2 and CO in either propane-expanded or propylene-expanded phases are observed to be greater than those in the neat organic solvents, by as high as 66% at 70°C and 1.5 MPa. By modeling the vapor and the liquid phases as pseudo-binary systems, the Peng-Robinson equation of state (PR-EoS) with van der Waals' mixing rules and binary interaction parameters is shown to satisfactorily predict the experimental VLE data. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-04T10:25:33.770979-05:
      DOI: 10.1002/aic.15988
       
  • A Pseudo-Transient Optimization Framework for Periodic Processes: Pressure
           Swing Adsorption and Simulated Moving Bed Chr
    • Authors: Calvin Tsay; Richard C. Pattison, Michael Baldea
      Abstract: Πeriodic systems are widely used in separation processes and in reaction engineering. They are designed for and operated at a cyclic steady state (CSS). Identifying and optimizing the CSS has proven to be computationally challenging. In this paper, we introduce a novel framework for equation-oriented simulation and optimization of cyclic processes. We propose a two-step reformulation of the process model, comprising, i) a full discretization of the time and spatial domains and ii) re-casting the discretized model as a differential-algebraic equation (DAE) system, for which we provide theoretical stability guarantees. Additionally, we establish a mathematical, structural connection between the CSS constraints and material recycling, which allows us to deal with these conditions via a “tearing” procedure. We integrate these developments in a pseudo-transient design optimization framework and present two extensive case studies: a simulated moving bed chromatography system and a pressure swing adsorption process. This article is protected by copyright. All rights reserved.
      PubDate: 2017-10-03T10:25:30.192562-05:
      DOI: 10.1002/aic.15987
       
  • Mixing Processes in the Cavity Transfer Mixer: a Thorough Study
    • Authors: Giovanna Grosso; Martien A. Hulsen, Arash Sarhangi Fard, Andrew Overend, Patrick D. Anderson
      Abstract: In many industrial applications, the quality of mixing between different materials is fundamental to guarantee the desired properties of products. However, properly modelling and understanding polymer mixing presents noticeable difficulties, because of the variety and complexity of the phenomena involved. This is also the case with the Cavity Transfer Mixer (CTM), an add-on to be mounted downstream of existing extruders, in order to improve distributive mixing. The present work proposes a fully three-dimensional model of the CTM: a finite element solver provides the transient velocity field, which is used in the mapping method implementation in order to compute the concentration field evolution and quantify mixing. Several simulations are run assessing the impact on mixing of geometrical and functioning parameters. In general, the number of cavities per row should be limited and the cavity size rather big in order to guarantee good mixing quality. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-29T11:44:51.410537-05:
      DOI: 10.1002/aic.15986
       
  • Detailed Thermodynamics for Analysis and Design of Ranque-Hilsch Vortex
           Tubes
    • Authors: John P. O'Connell
      Abstract: The Ranque-Hilsch vortex tube is a device for continuously separating an inlet pressurized fluid stream into two outlet streams of warmer and cooler temperatures at lower pressures, with no moving parts and without any heat or work effects. It has been applied to cool or heat small systems where refrigeration is impractical. Studies of the fluid mechanics inside the tube have not fully established the flow structure that provides the separation. Thermodynamic energy and entropy balances giving relations among properties and the relative amounts of the three fluid streams have been examined to determine consistency among measured data along with sensitivity of the phenomena to tube configuration, measurement error, and properties. The strong response of the temperature separation to small variations in entropy generation is shown to limit the possibilities for generalized prediction of vortex tube behavior. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-29T11:44:15.594323-05:
      DOI: 10.1002/aic.15985
       
  • Understanding Interfacial Behaviors of Isobutane Alkylation with C4 Olefin
           Catalyzed by Sulfuric Acid or Ionic Liquids
    • Authors: Weizhong Zheng; Huanying Wang, Wenxiu Xie, Ling Zhao, Weizhen Sun
      Abstract: The interfacial properties between the hydrocarbon phase including isobutane and 2-butene and the catalyst phase including H2SO4 or ionic liquids (ILs) with various alkyl chain length on their imidazolium cations have been investigated using molecular dynamics (MD) simulations. Compared to H2SO4, ILs could obviously improve the interfacial width, solubility and diffusion of reactants at the interface. The ILs with longer chains on cations exhibit a significant density enrichment of alkyl chains at the interface and tend to orient themselves with alkyl chains perpendicular to the interface and protruding into the reactants phase, which is in good agreement with the van der Waals energy between the reactants and cations of the ILs. The longer chains on cations could promote the interfacial width and facilitate the dissolution of isobutane in catalyst phase, and thus exhibits a better catalytic performance, which agrees well with alkylation experiments in this work. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-29T11:44:10.083427-05:
      DOI: 10.1002/aic.15984
       
  • Iron-based Electrochemically Mediated Atom Transfer Radical Polymerization
           with Tunable Catalytic Activity
    • Authors: Jun-Kang Guo; Zhou Yin-Ning, Luo Zheng-Hong
      Abstract: An iron-based electrochemically mediated atom transfer radical polymerization (eATRP) system with tunable catalytic activity was developed by adjusting the supporting electrolyte formula. Kinetic behaviors of the systems using four typical supporting electrolytes (namely, TBABr, TBAPF6, TBACl and TBABF4) were investigated. The type of anions was found to significantly affect the polymerization kinetics. TBAPF6 system proceeded with a considerable polymerization rate, whereas TBABr system showed better controllability. Importantly, the effect of supporting electrolyte on eATRP kinetics (mainly on ATRP equilibrium) was confirmed through kinetic modeling. Furthermore, the effect of catalyst loading using TBAPF6 as supporting electrolyte was also studied, and the results showed an uncontrolled polymerization for catalyst loading lower than 500 ppm. When hybrid supporting electrolyte (TBAPF6/TBABr) was used to tune catalytic activity, the polymerization slows down and the dispersity decreases with the increase in TBABr ratio. Polymers with a narrow molecular weight distribution (dispersity index
      PubDate: 2017-09-26T11:10:26.703103-05:
      DOI: 10.1002/aic.15978
       
  • Globally-Optimal Linear Approach for the Design of Process Equipment: the
           Case of Air Coolers
    • Authors: Priscila A. Souza; André L. H. Costa, Miguel J. Bagajewicz
      Abstract: In a recent article, Gonçalves et al.,11,12 introduced a linear and rigorous methodology for equipment design, in particular shell and tube heat exchanger. Here, we explore its application to air coolers, a problem that we solve globally for the first time. Because the approach is linear, results are globally optimal. The objective function is the total annualized cost. The constraints include the thermal and hydraulic modeling of the process stream flow in the tube bundle and the air flow through the finned surface. In addition, we worked on reducing computing time, through an analysis of different alternatives for the description of the original discrete variables organized in sets of binary variables. The performance of the proposed approach is illustrated through its comparison with an air cooler described in the literature. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-25T11:35:21.95513-05:0
      DOI: 10.1002/aic.15977
       
  • Modeling and Prediction of Protein Solubility using the Second Osmotic
           Virial Coefficient
    • Authors: Marcel Herhut; Christoph Brandenbusch, Gabriele Sadowski
      Abstract: The development of a precipitation or crystallization step requires knowing the solubility of the target protein and its crystallization behavior in aqueous solutions at different pH, temperatures and in the presence of precipitating agents, especially salts. Within this work, a solubility model for proteins based on the second osmotic virial coefficient B22 is developed. For this, a relation between protein solubility and B22 was combined with the extended DLVO model. This solubility model was then used to model and also predict the protein solubility of lysozyme and monoclonal antibody for different salts, salt concentrations, and pH. The modeled as well predicted B22 and protein solubility data of lysozyme in the presence of sodium chloride and sodium p-toluenesulfonate and of a monoclonal antibody in the presence of ammonium sulfate at different pH shows good agreement with experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2017-09-01T10:42:19.405106-05:
      DOI: 10.1002/aic.15944
       
  • Issue Information - Table of Contents
    • Pages: 1 - 1
      PubDate: 2017-12-11T10:22:33.536516-05:
      DOI: 10.1002/aic.15895
       
  • Kinetic and transport effects on enzymatic biocatalysis resulting from the
           PEGylation of cofactors
    • Authors: Harun F. Ozbakir; Scott Banta
      Pages: 12 - 17
      Abstract: The utilization of cofactor-dependent redox enzymes in bioprocess technologies requires low cost cofactor regeneration methods. PEGylated NAD(H) (PEG-NAD(H)) has been utilized in enzyme membrane reactors as a means to recover the cofactor; however, there is a lack of understanding of the effect of PEGylation on enzymatic activity, especially on the relationship between biocatalysis and transport phenomena. To explore this further, two redox enzymes (formate dehydrogenase (FDH) from Saccharomyces cerevisiae and NAD(H)-dependent d-lactate dehydrogenase (nLDH) from Escherichia coli) have been chosen and the kinetic effects caused by cofactor modifications (with PEG of three different chain lengths) have been investigated. The PEGylation did not impact the cofactor dissociation constants and mass transfer was not the rate-limiting step in biocatalysis for either enzyme. However, the PEG chain length had different impacts on the formation of enzyme/cofactor and/or enzyme/cofactor/substrate ternary complexes for the enzymes. © 2017 American Institute of Chemical Engineers AIChE J, 63: 12–17, 2018
      PubDate: 2017-08-09T22:15:33.507918-05:
      DOI: 10.1002/aic.15893
       
  • Kinetic Monte Carlo simulation for homogeneous nucleation of metal
           nanoparticles during vapor phase synthesis
    • Authors: Seyyed Ali Davari; Dibyendu Mukherjee
      Pages: 18 - 28
      Abstract: We present a free-energy driven kinetic Monte Carlo model to simulate homogeneous nucleation of metal nanoparticles (NPs) from vapor phase. The model accounts for monomer-cluster condensations, cluster–cluster collisions, and cluster evaporations simultaneously. Specifically, we investigate the homogeneous nucleation of Al NPs starting with different initial background temperatures. Our results indicate good agreement with earlier phenomenological studies using the Gibbs# free energy formulation from Classical Nucleation Theory (CNT). Furthermore, nucleation rates for various clusters are calculated through direct cluster observations. The steady-state nucleation rate estimated using two different approaches namely, the Yasuoka-Matsumoto (YM) and mean first passage time (MFPT) methods indicate excellent agreement with each other. Finally, our simulation results depict the expected increase in the entropy of mixing as clusters approach the nucleation barrier, followed by its subsequent drastic loss after the critical cluster formation resulting from first-order phase transitions. © 2017 American Institute of Chemical Engineers AIChE J, 63: 18–28, 2018
      PubDate: 2017-08-12T18:35:29.528086-05:
      DOI: 10.1002/aic.15887
       
  • Investigation of gas–solid bubbling fluidized beds using ECT with a
           modified Tikhonov regularization technique
    • Authors: Qiang Guo; Shuanghe Meng, Dehu Wang, Yinfeng Zhao, Mao Ye, Wuqiang Yang, Zhongmin Liu
      Pages: 29 - 41
      Abstract: Electrical capacitance tomography (ECT) provides a non-intrusive means to visualize cross-sectional material distribution of gas–solid bubbling fluidized beds. Successful application of ECT strongly depends on the image reconstruction algorithm used. For on-line measurements of bubbling fluidized beds, employing an algorithm that can produce high-quality images without extensive computation is necessary. Using the conventional Tikhonov regularization algorithm, image quality in the central area is basically satisfied but suffers from artifacts in the near-wall region. To solve this problem, a similar division operation learned from linear back projection was introduced to modify the conventional Tikhonov algorithm. Both numerical simulations and experiments were performed to evaluate the modified technique. The results indicate that the artifacts can be effectively removed and the reconstructed image quality is similar to Landweber method with dozens of iterations. Furthermore, the modified Tikhonov technique shows high accuracy when obtaining important hydrodynamic parameters in gas–solid bubbling fluidized beds. © 2017 American Institute of Chemical Engineers AIChE J, 63: 29–41, 2018
      PubDate: 2017-08-03T11:13:42.194822-05:
      DOI: 10.1002/aic.15879
       
  • CFD as an approach to understand flammable dust 20 L standard test: Effect
           of the ignition time on the fluid flow
    • Authors: Daniel Vizcaya; Andrés Pinilla, Mariangel Amín, Nicolás Ratkovich, Felipe Munoz, Carlos Murillo, Nathalie Bardin-Monnier, Olivier Dufaud
      Pages: 42 - 54
      Abstract: A computational study based on the Euler–Lagrange approach was developed for the characterization of flammable dusts in the 20 L sphere standard test. The aim of the study was to analyze some parameters that might affect the experimental data (e.g., cold turbulence and particle size). The turbulence of a wheat starch cloud was described with the Detached Eddy Simulation model. Both the pressure of the system and the RMS velocity were compared with the flow patterns established with a particle image velocimetry analysis. It was concluded that the rebound nozzle forms a cloud that is composed by clumps. This fact implies dissimilarities between the local concentrations and the nominal value. Finally, a granulometric analysis established that the mean diameter of the particle size distribution (PSD) decreased by 69% during the dispersion. Thus, it is suggested to consider the PSD at the ignition zone rather than the PSD of the sample. © 2017 American Institute of Chemical Engineers AIChE J, 63: 42–54, 2018
      PubDate: 2017-08-05T12:51:51.90227-05:0
      DOI: 10.1002/aic.15883
       
  • Design of mixed energy-integrated batch process networks by Pseudo-direct
           approach
    • Authors: Parikshit S. Shahane; Channamallikarjun S. Mathpati, Sujit S. Jogwar
      Pages: 55 - 67
      Abstract: In this article, a novel framework for the design of mixed (combined direct and indirect) integration for batch process systems is presented. The framework is based on the concept of pseudo-direct energy integration (PDEI) which reformulates indirect integration as direct integration using pseudo-process streams. Two algorithms are presented to achieve energy integration for batch processes operating cyclically (in a campaign mode). The first algorithm targets maximization of energy recovery and overcomes the limitations of some of the existing contributions for design of mixed integrated systems. The second algorithm provides a network reduction methodology to generate a cadre of integrated designs while exploring the trade-off between capital (number of heat exchangers and storage units) and operating costs (utility consumption). The proposed framework is illustrated using a benchmark example of two hot and two cold streams. © 2017 American Institute of Chemical Engineers AIChE J, 63: 55–67, 2018
      PubDate: 2017-07-24T15:42:20.224536-05:
      DOI: 10.1002/aic.15869
       
  • Improving the design of depth filters: A model-based method using optimal
           control theory
    • Authors: Michael Kuhn; Christoph Kirse, Heiko Briesen
      Pages: 68 - 76
      Abstract: Because there is no general design method for depth filters, especially for layered configurations, this methodological gap is addressed here. Using optimal control theory, paths of the filter coefficient, a measure for local filtration performance, are determined along the filter depth. An analytical optimal control solution is derived and used to validate the numerical algorithm. Two optimal control scenarios are solved numerically: In the first scenario, the goal of constant deposition along the filter depth is addressed. The second scenario aims at maximizing the time until some maximal pressure drop is reached. Furthermore, a computational strategy is presented to derive discrete layers suitable for practical design from the continuous optimal control solutions. All optimized scenarios are compared to one-layered filter designs and significant improvements are found. As this work is based on strongly validated and widely used filtration models, the presented methods are expected to have broad applicability. © 2017 American Institute of Chemical Engineers AIChE J, 63: 68–76, 2018
      PubDate: 2017-07-27T11:55:30.246424-05:
      DOI: 10.1002/aic.15866
       
  • Design and assessment of delay timer alarm systems for nonlinear chemical
           processes
    • Authors: Aditya Tulsyan; Feras Alrowaie, Bhushan Gopaluni
      Pages: 77 - 90
      Abstract: In process and manufacturing industries, alarm systems play a critical role in ensuring safe and efficient operations. The objective of a standard industrial alarm system is to detect undesirable deviations in process variables as soon as they occur. Fault detection and diagnosis systems often need to be alerted by an industrial alarm system; however, poorly designed alarms often lead to alarm flooding and other undesirable events. In this article, we consider the problem of industrial alarm design for processes represented by stochastic nonlinear time-series models. The alarm design for such complex processes faces three important challenges: (1) industrial processes exhibit highly nonlinear behavior; (2) state variables are not precisely known (modeling error); and (3) process signals are not necessarily Gaussian, stationary or uncorrelated. In this article, a procedure for designing a delay timer alarm configuration is proposed for the process states. The proposed design is based on minimization of the rate of false and missed alarm rates—two common performance measures for alarm systems. To ensure the alarm design is robust to any non-stationary process behavior, an expected-case and a worst-case alarm designs are proposed. Finally, the efficacy of the proposed alarm design is illustrated on a non-stationary chemical reactor problem. © 2017 American Institute of Chemical Engineers AIChE J, 63: 77–90, 2018
      PubDate: 2017-07-28T08:15:59.520227-05:
      DOI: 10.1002/aic.15860
       
  • Sustainable biopolymer synthesis via superstructure and multiobjective
           optimization
    • Authors: Ehecatl Antonio del Rio-Chanona; Dongda Zhang, Nilay Shah
      Pages: 91 - 103
      Abstract: Sustainable polymers derived from biomass have great potential to replace petrochemical based polymers and fulfill the ever-increasing market demand. To facilitate their industrialization, in this research, a comprehensive superstructure reaction network comprising a large number of reaction pathways from biomass to both commercialized and newly proposed polymers is constructed. To consider economic performance and environmental impact simultaneously, both process profit and green chemistry metrics are embedded into the multiobjective optimization framework, and MINLP is used to enable the effective selection of promising biopolymer candidates. Through this proposed approach, this study identifies the best biopolymer candidates and their most profitable and environmentally friendly synthesis routes under different scenarios. Moreover, the stability of optimization results regarding the price of raw materials and polymers and the effect of process scale on the investment cost are discussed in detail. These results, therefore, pave the way for future research on the production of sustainable biopolymers. © 2017 American Institute of Chemical Engineers AIChE J, 63: 91–103, 2018
      PubDate: 2017-07-31T12:30:48.276033-05:
      DOI: 10.1002/aic.15877
       
  • COSMO-based computer-aided molecular/mixture design: A focus on reaction
           solvents
    • Authors: Nick D. Austin; Nikolaos V. Sahinidis, Ivan A. Konstantinov, Daniel W. Trahan
      Pages: 104 - 122
      Abstract: In this article, we investigate reaction solvent design using COSMO-RS thermodynamics in conjunction with computer-aided molecular design (CAMD) techniques. CAMD using COSMO-RS has the distinct advantage of being a method based in quantum chemistry, which allows for the incorporation of quantum-level information about transition states, reactive intermediates, and other important species directly into CAMD problems. This work encompasses three main additions to our previous framework for solvent design (Austin et al., Chem Eng Sci. 2017;159:93–105): (1) altering the group contribution method to estimate hydrogen-bonding and non-hydrogen-bonding σ-profiles; (2) ab initio modeling of strong solute/solvent interactions such as H-bonding or coordinate bonding; and (3) solving mixture design problems limited to common laboratory and industrial solvents. We apply this methodology to three diverse case studies: accelerating the reaction rate of a Menschutkin reaction, controlling the chemoselectivity of a lithiation reaction, and controlling the chemoselectivity of a nucleophilic aromatic substitution reaction. We report improved solvents/mixtures in all cases. © 2017 American Institute of Chemical Engineers AIChE J, 63: 104–122, 2018
      PubDate: 2017-08-04T07:55:35.060381-05:
      DOI: 10.1002/aic.15871
       
  • A new superstructure optimization paradigm for process synthesis with
           product distribution optimization: Application to an integrated shale gas
           processing and chemical manufacturing process
    • Authors: Jian Gong; Fengqi You
      Pages: 123 - 143
      Abstract: We propose a novel process synthesis framework that combines product distribution optimization of chemical reactions and superstructure optimization of the process flowsheet. A superstructure with a set of technology/process alternatives is first developed. Next, the product distributions of the involved chemical reactions are optimized to maximize the profits of the effluent products. Extensive process simulations are then performed to collect high-fidelity process data tailored to the optimal product distributions. Based on the simulation results, a superstructure optimization model is formulated as a mixed-integer nonlinear program (MINLP) to determine the optimal process design. A tailored global optimization algorithm is used to efficiently solve the large-scale nonconvex MINLP problem. The resulting optimal process design is further validated by a whole-process simulation. The proposed framework is applied to a comprehensive superstructure of an integrated shale gas processing and chemical manufacturing process, which involves steam cracking of ethane, propane, n-butane, and i-butane. © 2017 American Institute of Chemical Engineers AIChE J, 63: 123–143, 2018
      PubDate: 2017-08-07T12:10:47.284747-05:
      DOI: 10.1002/aic.15882
       
  • Systematic analysis and optimization of power generation in pressure
           retarded osmosis: Effect of multistage design
    • Authors: Mingheng Li
      Pages: 144 - 152
      Abstract: This work presents a systematic method for analysis and optimization of specific energy production (SEP) of pressure retarded osmosis (PRO) systems employing single-stage configuration as well as multistage design with interstage hydro-turbines. It is shown that the SEP normalized by the draw solution feed osmotic pressure increases with the number of stages as well as a dimensionless parameter γtot=AtotLpπ0/Q0. As compared to the single-stage PRO, the multistage arrangement not only increases flux and volume gain, but also allows a stage-dependent, progressively decreasing hydraulic pressure, both of which contribute to enhanced SEP and power density. At the thermodynamic limit where γtot goes to infinity, the theoretical maximum SEP by an N-stage PRO system is N(1−qtot−1/N)π0, where qtot is the ratio of the draw solution flow rate at the outlet to the inlet on the system level. For single-stage PRO, it is no more than π0. For infinite number of stages, the theoretical limit becomes (ln⁡qtot)π0. SEP under realistic conditions and practical constraints on multistage design are discussed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 144–152, 2018
      PubDate: 2017-08-12T19:00:29.096698-05:
      DOI: 10.1002/aic.15894
       
  • Flame stabilization in a planar microcombustor partially filled with
           anisotropic porous medium
    • Authors: Long Meng; Jun Li, Qingqing Li, Junrui Shi
      Pages: 153 - 160
      Abstract: Heat recirculation through the combustor walls is responsible in sustaining flames in microcombustors. Incorporating porous medium into microcombustors helps further enhance heat recirculation via the solid matrix. However, the problem of anisotropy arises when the pore size is comparable to the characteristic length of microcombustors. To quantitatively address the problem, an experimental study on the flame stability limits of premixed H2/air in a planar microcombustor partially filled with porous medium is undertaken. Three folding schemes, namely, parallel sheets, streamwise flow passage, and streamwise flow blocking, are employed to realize the anisotropic properties. By varying the width (W) and position (Lout) of the porous medium, the effects of folding schemes on the critical flashback (Ф2), and breaking-through (Ф3) conditions are examined. The experimental results indicate that the disturbance to flow velocity in the transverse direction mainly influences Ф2, while Ф3 is greatly affected by the blocking normal to the flow direction. © 2017 American Institute of Chemical Engineers AIChE J, 63: 153–160, 2018
      PubDate: 2017-07-24T17:06:30.449868-05:
      DOI: 10.1002/aic.15862
       
  • Considerations on film reactivity in the aqueous biphasic hydroformylation
    • Authors: H. Warmeling; A.-C. Schneider, A. J. Vorholt
      Pages: 161 - 171
      Abstract: In experiments and kinetic models it was shown that the reaction rate of the biphasic aqueous hydroformylation of 1-octene is linear dependent on the created interfacial area. This phenomenon is directly linked to the question whether the reaction takes place in the bulk phase and is mass transfer limitation or at the surface which would mean an increase of reaction space. To evaluate the place of reaction a mass transfer analysis has been carried out. No mass transfer limitation for the gaseous components carbon monoxide and hydrogen as well as the olefin 1-octene was determined for the aqueous catalyst phase by calculating the Hatta numbers. With this observation it is possible to exclude the mass transfer as a potential influence and hence the aqueous bulk as the place of reaction. Thus the reaction is most probably surface active. This can be either explained the increase in film volume fraction where non-polar substrate as well as polar catalyst complex is present or through an increased catalyst concentration at the surface through dipole moment fluctuations. © 2017 American Institute of Chemical Engineers AIChE J, 63: 161–171, 2018
      PubDate: 2017-08-04T08:00:38.68459-05:0
      DOI: 10.1002/aic.15884
       
  • Adiabatic time to maximum rate evaluation using an analytical approach
    • Authors: Roberto Sanchirico
      Pages: 172 - 179
      Abstract: This article presents an analytical method for the calculation of the adiabatic time to maximum rate. The procedure is developed considering a thermal decomposition process described by a simple n-order kinetic and is based on the introduction of a special function that is possible by integrating analytically. The application of the method requires the knowledge of the thermokinetic parameters of the process under study and allows the calculation of the adiabatic time to maximum rate without the numerical integration of the heat and mass balance equations or the use of relationships based on particular simplifying hypotheses. Its validity has been demonstrated considering numerical and real experiments (thermal decomposition of trityl azide) providing in both cases times to maximum rate values which are very close to the real ones. © 2017 American Institute of Chemical Engineers AIChE J, 63: 172–179, 2018
      PubDate: 2017-08-25T23:15:33.19719-05:0
      DOI: 10.1002/aic.15923
       
  • Pressure drop and saturation of nonwettable coalescing filters at
           different loading rates
    • Authors: Cheng Chang; Zhongli Ji, Jialin Liu
      Pages: 180 - 185
      Abstract: The effect of layers on the pressure drop and saturation of nonwettable filters at different loading rates were investigated. It was found that both the jump and channel pressure drop depended on the loading rate. The total channel pressure drop of different filters seemed independent of the number of layers. At the same loading rate, more layers led to fewer channels per layer and larger size of each channel. Moreover, according to the evolution of channel number and size, there was a reorganization of channel structure in the filters. © 2017 American Institute of Chemical Engineers AIChE J, 63: 180–185, 2018
      PubDate: 2017-08-01T11:55:35.905456-05:
      DOI: 10.1002/aic.15863
       
  • Some mechanistic insights into the action of facilitating agents on gas
           permeation through glassy polymeric membranes
    • Authors: Md Oayes Midda; Akkihebbal K. Suresh
      Pages: 186 - 199
      Abstract: Incorporation of facilitating agents is one of the promising strategies being researched in recent years to cross the Robeson bounds for gas separations using polymeric membranes. The ways in which such inclusions modify the performance of membranes are not always clear. Here, we study the performance of two glassy membranes, Polyfurfuryl alcohol and Polysulfone, in O2/N2 and CO2/N2 separations, with Cobalt phthalocyanine in insoluble and solubilized forms as the facilitating agent. The results show that in general, three effects are important: (1) a barrier effect, (2) a facilitation effect, and (3) morphological effects on the polymer matrix due to an incompatibility between the particles and the polymer. These results provide some insight into the action of facilitating agents in soluble and insoluble form, when used as membrane additives. © 2017 American Institute of Chemical Engineers AIChE J, 63: 186–199, 2018
      PubDate: 2017-08-04T07:50:52.510741-05:
      DOI: 10.1002/aic.15873
       
  • Influence and CFD analysis of cooling air velocity on the purification of
           aqueous nickel sulfate solutions by freezing
    • Authors: Mehdi Hasan; Roman Filimonov, Miia John, Joonas Sorvari, Marjatta Louhi-Kultanen
      Pages: 200 - 208
      Abstract: Finite energy resources and their rapidly waning imprint necessitate a sustainable wastewater treatment method. Nature could be exploited to freeze wastewater in locations which experience subzero temperatures during winter. The two most vital components that influence the efficiency of natural freezing are the ambient temperature and air velocity. The turbulent and unsteady air-cooled natural freezing is simulated for ice crystallization from 0.1 wt % and 1 wt % NiSO4 (aq) solutions. The efficiency of natural freezing is tested for different air velocities (2 ms−1, 5 ms−1) and levels of undercooling (ΔT = 0.5°C, 1°C) from the freezing temperature of the corresponding solution. The airflow in the winter simulator is modeled by computational fluid dynamics to investigate its behavior and to assess its effect on freezing. © 2017 American Institute of Chemical Engineers AIChE J, 63: 200–208, 2018
      PubDate: 2017-08-08T09:00:45.543007-05:
      DOI: 10.1002/aic.15885
       
  • Protic ionic liquid as excellent shuttle of MDEA for fast capture of CO2
    • Authors: Wen-Tao Zheng; Kuan Huang, You-Ting Wu, Xing-Bang Hu
      Pages: 209 - 219
      Abstract: A cheap protic ionic liquid (PIL), 3-(Dimethylamino)-1-propylamine acetate (abbreviated as [DMAPAH][Ac]), is investigated in this work as the activator of N-methyldiethanolamine (MDEA) for fast capture of CO2. The PIL-activated MDEA solutions show excellent performance in absorption rate and capacity (≥2.5 mol·kg−1). A novel absorption mechanism is proposed to account for the phenomenon, where the shuttling role of the PIL is described in detail. Additionally, the enthalpy change ΔHSOL (−45 to −52 kJ·mol−1), the turnover number of the PIL and the regeneration efficiency (>92%) are also measured. All these data show that the PIL-mediated MDEA solutions may be used as a kind of promising absorbents for fast capture of CO2. © 2017 American Institute of Chemical Engineers AIChE J, 63: 209–219, 2018
      PubDate: 2017-08-25T23:20:55.47728-05:0
      DOI: 10.1002/aic.15921
       
  • Tensile modulus of polymer/CNT nanocomposites containing networked and
           dispersed nanoparticles
    • Authors: Yasser Zare; Kyong Yop Rhee
      Pages: 220 - 225
      Abstract: The properties of three-dimensional networks of nanoparticles in polymer/carbon nanotubes (CNT) nanocomposites (PCNT) are particularly interesting from fundamental and application views. In this article, a new model is suggested for predicting the tensile modulus of PCNT using the Ouali and Paul models. The Ouali model considers the network of CNT in a polymer matrix, while the Paul model predicts the tensile modulus of samples containing dispersed nanoparticles. The predictions of the suggested approach are compared with experimental data from several samples. Also, the roles of the main parameters in the tensile modulus of PCNT are evaluated. The predictions agree with the experimental results at different filler concentrations. The roles of these parameters on the tensile modulus of PCNT are discussed based on the properties of CNT networks. © 2017 American Institute of Chemical Engineers AIChE J, 63: 220–225, 2018
      PubDate: 2017-08-12T18:55:24.792918-05:
      DOI: 10.1002/aic.15891
       
  • Multi-criteria optimization for parameterization of SAFT-type equations of
           state for water
    • Authors: Esther Forte; Jakob Burger, Kai Langenbach, Hans Hasse, Michael Bortz
      Pages: 226 - 237
      Abstract: Finding appropriate parameter sets for a given equation of state (EoS) to describe different properties of a certain substance is an optimization problem with conflicting objectives. Such problem is commonly addressed by single-criteria optimization in which the different objectives are lumped into a single goal function. We show how multi-criteria optimization (MCO) can be beneficially used for parameterizing equations of state. The Pareto set, which comprises a set of optimal solutions of the MCO problem, is determined. As an example, the perturbed-chain statistical associating fluid theory (PC-SAFT) EoS is used and applied to the description of the thermodynamic properties of water, focusing on saturated liquid density and vapor pressure. Different options to describe the molecular nature of water by the PC-SAFT EoS are studied and for all variants, the Pareto sets are determined, enabling a comprehensive assessment. When compared to literature models, Pareto optimization yields improved models. © 2017 American Institute of Chemical Engineers AIChE J, 63: 226–237, 2018
      PubDate: 2017-07-24T17:03:42.208017-05:
      DOI: 10.1002/aic.15857
       
  • Development of 3D polymer DFT and its application to molecular transport
           through a surfactant-covered interface
    • Authors: Yu Liu; Honglai Liu
      Pages: 238 - 249
      Abstract: We have developed a three-dimensional polymer density functional theory (DFT) and applied it to predict the thermodynamic and structural information of molecular transport through a surfactant-covered interface. The green recursive function method has been employed to consider the chain conformation effect. The reference ideal gas method has been developed, extending it from molecular DFT to polymer DFT, with a universal form to calculate thermodynamic properties such as the grand potential and free energy. We have demonstrated the accuracy of the theory by comparing it to available simulations. Furthermore, we have applied the theory to predict the free energy barrier and density profile of molecular transport through a surfactant-covered interface. The free energy profile provides reasonable predictions of the transition velocity, while the density profile gives insight into the microstructural information of the transport process, which is consistent with the available molecular simulations. © 2017 American Institute of Chemical Engineers AIChE J, 63: 238–249, 2018
      PubDate: 2017-07-24T17:04:35.740263-05:
      DOI: 10.1002/aic.15858
       
  • Next generation of low global warming potential refrigerants:
           Thermodynamic properties molecular modeling
    • Authors: Wael A. Fouad; Lourdes F. Vega
      Pages: 250 - 262
      Abstract: The recent global agreement signed in Kigali to limit the use of hydrofluorocarbons (HFCs) as refrigerants, starting by 2019, has promoted an active area of research toward the development of low global warming potential (GWP) new refrigerants. Hydrofluoroolefins (HFOs) have been proposed as a low GWP alternative to third generation HFC refrigerants, but further work on fully characterizing them and their blends with other compounds is still required to fully assess their performance to replace the ones in current use. In this work, the polar and perturbed chain statistical associating fluid theory coupled with the density gradient theory is used to predict the vapor–liquid equilibrium, isobaric heat capacity, speed of sound, and surface tension of selected HFC and HFO-based commercial azeotropic blends as fourth generation low GWP refrigerants, seeking for a predictive tool for these properties. © 2017 American Institute of Chemical Engineers AIChE J, 63: 250–262, 2018
      PubDate: 2017-07-24T17:06:07.391427-05:
      DOI: 10.1002/aic.15859
       
  • The maximum flammable content for binary aqueous–organic mixtures not to
           flash and their maximum flash points
    • Authors: Horng-Jang Liaw
      Pages: 263 - 271
      Abstract: Aqueous–organic solutions can flash only over a limited composition range. This manuscript proposes a model to estimate the two critical parameters, maximum flammable content not to flash and the maximum flash point temperature, in judging whether an aqueous–organic solution is flammable or not. The results are applicable to flammability elimination and flammability hazard assessment of liquid solutions. Validation of this model was performed with measurements for 14 aqueous–organic miscible and partially miscible mixtures. Various mixtures were tested including alcohols, ketones, and esters in aqueous solutions. Overall, the estimation of the maximum flash point value and maximum flammable content not to flash were acceptable when using the proposed model. The termination of the flash for aqueous solutions was clarified to be the nonflammability of the vapor phase resulting from the high-steam concentration when the temperature of such solutions is greater than the maximum flash point. © 2017 American Institute of Chemical Engineers AIChE J, 63: 263–271, 2018
      PubDate: 2017-07-28T02:15:06.588126-05:
      DOI: 10.1002/aic.15867
       
  • Development of a COSMO-RS based model for the calculation of phase
           equilibria in electrolyte systems
    • Authors: Thomas Gerlach; Simon Müller, Irina Smirnova
      Pages: 272 - 285
      Abstract: A new electrolyte model, which is based on the predictive thermodynamic model COSMO-RS, is presented. For this purpose, an implementation of COSMO-RS that allows the integration of multiple segment descriptors was developed. To aid in the development of the electrolyte model, a new technique is presented that allows the evaluation of the different contributions of the interaction terms of COSMO-RS to the partial molar enthalpies. General empirical interaction energy equations are introduced into the electrolyte model. They are parameterized based on a large training set of mean ionic activity coefficients as well as liquid–liquid equilibrium data close to ambient conditions. The model is shown to be capable of predicting properties of systems containing anions that were not part of the training set of the model. Furthermore, it is demonstrated that the model can also lead to satisfying predictions if compared to vapor–liquid equilibrium data. © 2017 American Institute of Chemical Engineers AIChE J, 63: 272–285, 2018
      PubDate: 2017-07-31T09:20:45.547533-05:
      DOI: 10.1002/aic.15875
       
  • A comprehensive analysis of the BET area for nanoporous materials
    • Authors: Yun Tian; Jianzhong Wu
      Pages: 286 - 293
      Abstract: The Brunauer-Emmett-Teller (BET) method has been used extensively to characterize the surface areas of porous materials by semiempirical fitting of gas-adsorption isotherms. However, questions often arise concerning the applicability and the exact meaning of the BET areas. In particular, there has been much debate about whether the BET method provides a faithful description of the geometrical areas of porous materials if the atomic structures are exactly known. In this work, we provide a comprehensive analysis of the BET areas for both model slit pores and crystalline porous materials using the grand canonical Monte Carlo simulation. Based on extensive simulation data for nitrogen adsorption at 77 K and the conventional models of materials characterization, we find no simple correlation between the BET and geometrical surface areas. For materials with the same BET area, their geometric surface areas may vary over one order of magnitude. © 2017 American Institute of Chemical Engineers AIChE J, 63: 286–293, 2018
      PubDate: 2017-08-01T12:01:00.84775-05:0
      DOI: 10.1002/aic.15880
       
  • Spontaneous imbibition of liquids in glass-fiber wicks. Part I: Usefulness
           of a sharp-front approach
    • Authors: M. Amin F. Zarandi; Krishna M. Pillai, Adam S. Kimmel
      Pages: 294 - 305
      Abstract: Spontaneous imbibition of a liquid into glass-fiber wicks is modeled using the single-phase Darcy's law after assuming a sharp flow-front marked by full saturation behind the front occurring in a transversely isotropic porous medium. An analytical expression for the height of the wicking flow-front as a function of time is tested through comprehensive experiments involving using eight different wicks and one oil as the wicking liquid. A good fit with experimental data is obtained without using any fitting parameter. The contact-angle is observed to be important for the success of the model—lower contact angle cases marked by higher capillary pressures were predicted the best. The proposed model provides a nice upper bound for all the wicks, thereby establishing its potential as a good tool to predict liquid absorption in glass-fiber wicks. However, the sharp-front model is unable to explain region of partial saturation, thereby necessitating the development of part II of this article series (Zarandi and Pillai, Spontaneous Imbibition of Liquid in Glass fiber wicks. Part II: Validation of a Diffuse-Front Model. AIChE J, 64: 306–315, 2018) using Richard's equation. © 2017 American Institute of Chemical Engineers AIChE J, 63: 294–305, 2018
      PubDate: 2017-09-28T14:25:31.024074-05:
      DOI: 10.1002/aic.15965
       
  • Spontaneous imbibition of liquid in glass fiber wicks, Part II: Validation
           of a diffuse-front model
    • Authors: M. Amin F. Zarandi; Krishna M. Pillai
      Pages: 306 - 315
      Abstract: In Part I (Zarandi MAF, Pillai KM. Spontaneous Imbibition of Liquids in Glass-Fiber Wicks. Part I: Usefulness of a Sharp-Front Approach. AIChE J, 64: 294–305, 2018), a model based on sharp liquid-front was proposed where a good match with the experimental data was achieved. However, the model failed to account for partial saturations in the wicks. Here, Richard's equation to predict liquid saturation is tried where the equation is solved numerically in 3D using COMSOL and analytically in 1D using Mathematica for glass-fiber wicks after treating them as transversely-isotropic porous media. As a novel contribution, relative permeability and capillary pressure are determined directly from pore-scale simulations in wick microstructure using the state-of-the-art software GeoDict. The saturation along the wick length is determined experimentally through a new liquid-N2 based freezing technique. After including the gravity effect, good agreements between the numerical/analytical predictions and experimental results are achieved in saturation distributions. We also validated the Richard's equation based model while predicting absorbed liquid-mass into the wick as function of time. © 2017 American Institute of Chemical Engineers AIChE J, 63: 306–315, 2018
      PubDate: 2017-07-24T17:00:06.381349-05:
      DOI: 10.1002/aic.15856
       
  • Numerical and experimental investigation on surface air entrainment
           mechanisms of a novel long-short blades agitator
    • Authors: Yueqiao Zhang; Xiang Pan, Yaohua Wang, Peicheng Luo, Hua Wu
      Pages: 316 - 325
      Abstract: We investigate numerically and experimentally the mechanisms of surface air entrainment in the vessels equipped with the long-short blades agitator. VOF method coupled with LES model is used to visualize the surface air entrainment process. In the case of partial submergence of the long blades (LBs), the interaction of the LBs with the liquid free surface creates a depression behind the LBs. Backfilling of the liquid into the depression leads to gas separation and entrapping into the liquid. The critical tip velocity of the LBs, utip,c, for the onset of gas entrainment is measured in vessels with diameters, T = 200∼600 mm. It is found that when H/T ≥ 1.0, utip,c is determined by the LBs, independent of the liquid level. utip,c is also affected by the size of the vessel through the diameter of the sweeping circle of the LBs, but for substantially large vessels, it approaches a constant value. © 2017 American Institute of Chemical Engineers AIChE J, 63: 316–325, 2018
      PubDate: 2017-07-24T17:07:17.428745-05:
      DOI: 10.1002/aic.15865
       
  • A semianalytical model for simulating real gas transport in nanopores and
           complex fractures of shale gas reservoirs
    • Authors: Weihong Wang; Wei Yu, Xiaohu Hu, Hua Liu, Youguang Chen, Kan Wu, Biyi Wu
      Pages: 326 - 337
      Abstract: An efficient gridless semianalytical model was developed to simulate real gas transport in shale formation with nanopores and complex fracture geometry. This model incorporates multiple physics such as gas desorption, adsorbed gas porosity, gas slippage and diffusion, residual water saturation, non-Darcy flow, choke skin, and pressure-dependent matrix permeability, and fracture conductivity. Additionally, this model is easy to handle complex fracture geometry through dividing fractures into a number of segments and nodes. We verified the model against a numerical model and an analytical model for bi-wing hydraulic fractures. After validation, the impacts of all these physics on well performance were evaluated in detail through a series of case studies. The simulation results confirm that modeling of gas production from complex fracture geometry as well as modeling important physics in shale gas reservoirs is significant. This study improves our understanding of critical physics affecting gas recovery in shale gas reservoirs. © 2017 American Institute of Chemical Engineers AIChE J, 63: 326–337, 2018
      PubDate: 2017-08-01T11:40:43.725737-05:
      DOI: 10.1002/aic.15881
       
  • Molecular simulation study of aluminum–noble gas interfacial thermal
           accommodation coefficients
    • Authors: Haoyan Sha; Roland Faller, Gulcin Tetiker, Peter Woytowitz
      Pages: 338 - 345
      Abstract: Thermal accommodation coefficients (TAC) between aluminum and noble gases were studied with molecular dynamics (MD) simulations. Gases interacting with aluminum substrates were modeled by MD with gas velocities sampled from the Maxwell–Boltzmann distribution to give accumulated TAC results. Different implementations of the equation to calculate the TAC, which differ in the amount of information gleaned from MD and the corresponding simulation results, were carefully discussed. The best formula for MD modeling in finite simulation time was determined. Additionally, the influence of the combining rules applied on aluminum–noble gas interatomic potential was characterized with the well-known Lennard–Jones 12–6 potential combined with Lorentz–Berthelot and Fender–Halsey mixing rules. The results were compared with experimental values and previous analytical model. TACs simulated with Fender–Halsey rules present excellent agreement with the experimental values. Detailed TAC distributions and accumulated TAC convergence are also included. © 2017 American Institute of Chemical Engineers AIChE J, 63: 338–345, 2018
      PubDate: 2017-08-03T11:05:34.82783-05:0
      DOI: 10.1002/aic.15886
       
  • Formation of liquid–liquid slug flow in a microfluidic T-junction:
           Effects of fluid properties and leakage flow
    • Authors: Chaoqun Yao; Yanyan Liu, Chao Xu, Shuainan Zhao, Guangwen Chen
      Pages: 346 - 357
      Abstract: Characteristics of liquid–liquid slug flow are investigated in a microchannel with focus on the leakage flow that bypasses droplets through channel gutters. The results show that the leakage flow rate varies in a range of 10.7–53.5% and 8.3–30.9% of the feed flow rate, during the droplet formation (i.e., at T-junction) and downstream flow (i.e., in the main channel), respectively, which highly depends on Ca number and wetting condition. Empirical correlations are proposed to predict them for perfectly and partially wetting conditions. Leakage flow contribution is further used to improve the Garstecki model for size scaling in order to extend its suitability for both squeezing and shearing regimes. The instantaneous flow rates of the immiscible phases are found to fluctuate periodically with the formation cycles, but in opposite behavior. The effect of the presence of leakage flow on such fluctuation are investigated and compared with gas–liquid systems. © 2017 American Institute of Chemical Engineers AIChE J, 63: 346–357, 2018
      PubDate: 2017-08-03T11:10:34.385716-05:
      DOI: 10.1002/aic.15889
       
  • Steady microfluidic measurements of mutual diffusion coefficients of
           liquid binary mixtures
    • Authors: Anne Bouchaudy; Charles Loussert, Jean-Baptiste Salmon
      Pages: 358 - 366
      Abstract: We present a microfluidic method leading to accurate measurements of the mutual diffusion coefficient of a liquid binary mixture over the whole solute concentration range in a single experiment. This method fully exploits solvent pervaporation through a poly(dimethylsiloxane) (PDMS) membrane to obtain a steady concentration gradient within a microfluidic channel. Our method is applicable for solutes which cannot permeate through PDMS, and requires the activity and the density over the full concentration range as input parameters. We demonstrate the accuracy of our methodology by measuring the mutual diffusion coefficient of the water (1) + glycerol (2) mixture, from measurements of the concentration gradient using Raman confocal spectroscopy and the pervaporation-induced flow using particle tracking velocimetry. © 2017 American Institute of Chemical Engineers AIChE J, 63: 358–366, 2018
      PubDate: 2017-08-08T08:56:28.675988-05:
      DOI: 10.1002/aic.15890
       
  • Interface-shrinkage-driven breakup of droplets in microdevices with
           different dispersed fluid channel shape
    • Authors: Wenjie Lan; Zhihui Wang, Yinjie Du, Xuqiang Guo, Shaowei Li
      Pages: 367 - 375
      Abstract: A new droplet breakup mechanism is previously proposed—interface-shrinkage-driven breakup. In coaxial microdevices, when the contact angle between the continuous phase and dispersed fluid channel (DFC) is sufficiently low, the new mechanism instead of the classic shear-driven mechanism dominates the breakup. The present study further investigated the new mechanism in microdevices with DFCs of different shape. Critical contact angles in different devices were determined by theoretical analysis and verified by experiments. It was found that the critical contact angle for the new mechanism depends on the shape of the DFC. The droplet size was measured for different devices when the new mechanism dominated the breakup. In contrast to the case for the shear-driven mechanism, the droplet size is little affected by the capillary number. Mathematical models were established to predict the droplet size in different devices and results were found to agree well with experimental results. © 2017 American Institute of Chemical Engineers AIChE J, 63: 367–375, 2018
      PubDate: 2017-08-23T10:55:45.567643-05:
      DOI: 10.1002/aic.15932
       
  • Bubble splitting under gas–liquid–liquid three-phase flow in a double
           T-junction microchannel
    • Authors: Yanyan Liu; Jun Yue, Shuainan Zhao, Chaoqun Yao, Guangwen Chen
      Pages: 376 - 388
      Abstract: Gas–aqueous liquid–oil three-phase flow was generated in a microchannel with a double T-junction. Under the squeezing of the dispersed aqueous phase at the second T-junction (T2), the splitting of bubbles generated from the first T-junction (T1) was investigated. During the bubble splitting process, the upstream gas–oil two-phase flow and the aqueous phase flow at T2 fluctuate in opposite phases, resulting in either independent or synchronous relationship between the instantaneous downstream and upstream bubble velocities depending on the operating conditions. Compared with two-phase flow, the modified capillary number and the ratio of the upstream velocity to the aqueous phase velocity were introduced to predict the bubble breakup time. The critical bubble breakup length and size laws of daughter bubbles/slugs were thereby proposed. These results provide an important guideline for designing microchannel structures for a precise manipulation of gas–liquid–liquid three-phase flow which finds potential applications among others in chemical synthesis. © 2017 American Institute of Chemical Engineers AIChE J, 63: 376–388, 2018
      PubDate: 2017-08-25T23:30:33.174107-05:
      DOI: 10.1002/aic.15920
       
  • Particle-resolved PIV experiments of solid-liquid mixing in a turbulent
           stirred tank
    • Authors: Genghong Li; Zhengming Gao, Zhipeng Li, Jiawei Wang, J. J. Derksen
      Pages: 389 - 402
      Abstract: Particle Image Velocimetry (PIV) experiments on turbulent solid-liquid stirred tank flow with careful refractive index matching of the two phases have been performed. The spatial resolution of the PIV data is finer than the size of the spherical, uniformly sized solid particles, thereby providing insight in the flow around individual particles. The impeller is a down-pumping pitch-blade turbine. The impeller-based Reynolds number has been fixed to Re = 104. Overall solids volume fractions up to 8% have been investigated. The PIV experiments are impeller-angle resolved, that is, conditioned on the angular position of the impeller. The two-phase systems are in partially suspended states with an inhomogeneous distribution of solids: high solids loadings near the bottom and near the outer walls of the tank, much less solids in the bulk of the tank. The liquid velocity fields show very strong phase coupling effects with the particles increasingly attenuating the overall circulation patterns as well as the liquid velocity fluctuation levels when the solids volume fraction is increased. © 2017 American Institute of Chemical Engineers AIChE J, 63: 389–402, 2018
      PubDate: 2017-08-25T23:16:01.125828-05:
      DOI: 10.1002/aic.15924
       
 
 
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