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  Subjects -> ENGINEERING (Total: 1961 journals)
    - CHEMICAL ENGINEERING (153 journals)
    - CIVIL ENGINEERING (149 journals)
    - ELECTRICAL ENGINEERING (81 journals)
    - ENGINEERING (1114 journals)
    - ENGINEERING MECHANICS AND MATERIALS (292 journals)
    - HYDRAULIC ENGINEERING (46 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (74 journals)

ENGINEERING (1114 journals)            First | 1 2 3 4 5 6 7 8 | Last

Biointerphases     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Engineering     Hybrid Journal   (Followers: 9)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 12)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 4)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 15)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 4)
Biomedical Microdevices     Hybrid Journal   (Followers: 7)
Biomedizinische Technik - Biomedical Engineering     Full-text available via subscription  
Biomicrofluidics     Open Access   (Followers: 2)
BioNanoMaterials     Full-text available via subscription   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 20)
Boletin Cientifico Tecnico INIMET     Open Access  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access  
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 1)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 11)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 3)
Case Studies in Thermal Engineering     Open Access   (Followers: 1)
Catalysis Communications     Hybrid Journal   (Followers: 4)
Catalysis Letters     Hybrid Journal   (Followers: 1)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 4)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysis Today     Hybrid Journal   (Followers: 6)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 2)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 1)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 1)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 1)
Chinese Journal of Engineering     Open Access  
Chinese Science Bulletin     Open Access  
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access  
Ciencias Holguin     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 8)
City, Culture and Society     Hybrid Journal   (Followers: 18)
Clay Minerals     Full-text available via subscription   (Followers: 3)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Clinical Science     Full-text available via subscription   (Followers: 3)
Coal Science and Technology     Full-text available via subscription   (Followers: 2)
Coastal Engineering     Hybrid Journal   (Followers: 6)
Coastal Engineering Journal     Hybrid Journal   (Followers: 1)
Coatings     Open Access   (Followers: 1)
Cogent Engineering     Open Access  
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 5)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 10)
Communications Engineer     Hybrid Journal  
Communications in Information Science and Management Engineering     Open Access   (Followers: 7)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 3)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 9)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Composite Structures     Hybrid Journal   (Followers: 37)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 29)
Composites Part B : Engineering     Hybrid Journal   (Followers: 26)
Composites Science and Technology     Hybrid Journal   (Followers: 34)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 11)
Computational Optimization and Applications     Hybrid Journal   (Followers: 5)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 6)
Computer Science and Engineering     Open Access   (Followers: 8)
Computers & Geosciences     Hybrid Journal   (Followers: 6)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 4)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 5)
Computing and Visualization in Science     Hybrid Journal   (Followers: 3)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 10)
Conciencia Tecnologica     Open Access   (Followers: 1)
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 4)
Control Engineering Practice     Hybrid Journal   (Followers: 12)
Control Theory and Informatics     Open Access   (Followers: 4)
Corrosion Science     Hybrid Journal   (Followers: 19)
Corrosion Series     Full-text available via subscription   (Followers: 5)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 2)
Design Journal     Full-text available via subscription   (Followers: 15)
Designed Monomers and Polymers     Hybrid Journal   (Followers: 2)
Designs, Codes and Cryptography     Hybrid Journal   (Followers: 4)
Developments in Clay Science     Full-text available via subscription  

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover AIChE Journal
   Journal TOC RSS feeds Export to Zotero [20 followers]  Follow    
   Hybrid Journal Hybrid journal (It can contain Open Access articles)
     ISSN (Print) 0001-1541 - ISSN (Online) 1547-5905
     Published by John Wiley and Sons Homepage  [1604 journals]   [SJR: 0.889]   [H-I: 94]
  • Synthesis of optimal thermal membrane distillation networks
    • Authors: Ramón González‐Bravo; Madhav Nyapathi, Nesreen Elsayed, Fabricio Nápoles‐Rivera, José María Ponce‐Ortega, Mahmoud M. El‐Halwagi
      Pages: n/a - n/a
      Abstract: Thermal membrane distillation (TMD) is an emerging separation method which involves simultaneous heat and mass transfer through a hydrophobic semi‐permeable membrane. Traditionally, studies of this technology have focused on the performance of individual modules. Because of purity and recovery requirements, multiple TMD modules may be used in various configurations including series, parallel, and combinations. Furthermore, there may be a need to reroute streams from one module to another or to recycle a stream to the same unit. The objective of this paper is to develop a systematic approach to synthesize an optimal TMD network. A structural representation is developed to embed potential configurations of interest. A mathematical formulation is developed to transform the design problem into an optimization task that seeks to minimize the cost of the system. Two case studies are presented to illustrate the applicability of the developed approach and its merit over conventional design scenarios. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-16T04:33:40.242184-05:
      DOI: 10.1002/aic.14652
       
  • Sustainable chemical engineering: Dealing with “wicked”
           sustainability problems
    • Authors: Adisa Azapagic; Slobodan Perdan
      Pages: n/a - n/a
      PubDate: 2014-10-16T04:12:33.963518-05:
      DOI: 10.1002/aic.14650
       
  • Membrane reactor immobilized with palladium‐loaded polymer nanogel
           for continuous‐flow Suzuki coupling reaction
    • Authors: Hirokazu Seto; Tamami Yoneda, Takato Morii, Tatsuya Murakami, Yu Hoshino, Yoshiko Miura
      Pages: n/a - n/a
      Abstract: A catalytic membrane reactor, which was immobilized with palladium‐loaded nanogel particles, was developed for continuous‐flow Suzuki coupling reaction. Palladium‐loaded membranes were prepared by immobilization of nanogel particles, adsorption of palladium ions, and reduction into palladium(0). The presence of palladium in the membrane was confirmed by the scanning electron microscopy; palladium aggregation was not observed. The catalytic activity of the membrane reactor in continuous‐flow Suzuki coupling reaction was approximately double that of a comparable reactor in which palladium ions were directly adsorbed onto an aminated membrane. This was attributed to the formation of small palladium particles. The reusability in the continuous‐flow system was higher than that in a batch system, and the palladium‐loaded membrane reactor had high long‐term stability. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-16T04:12:33.189128-05:
      DOI: 10.1002/aic.14653
       
  • Motion and stability of cones in a yield stress fluid
    • Authors: Fiacre Ahonguio; Laurent Jossic, Albert Magnin
      Pages: n/a - n/a
      Abstract: This experimental study focuses on the creeping flow of a shear thinning yield stress fluid around conical obstacles. The flow has been analyzed in steady state and with adherence conditions. Firstly, the influences of the cone apex angle and of the Oldroyd number, i.e. the ratio between plastic and viscous effects, on the drag coefficient have been analyzed. Correlations have been proposed to model the evolution of this coefficient as a function of these two parameters. The analysis provides a new alternative for measuring the yield stress. Then, the kinematic fields around the cones have been analyzed. These fields enable to describe the rigid zones and the sheared zone developing around the lateral edge of the cones as a function of the cone apex angle. Moreover, the wall shear stresses estimated from the PIV measurements have enabled to quantify the contribution of the lateral drag force in the drag force. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-14T22:11:44.952325-05:
      DOI: 10.1002/aic.14651
       
  • Comparative study on electrical properties of copper
           nanowire/polypropylene and carbon nanotube/polypropylene composites
    • Authors: Yan Li; Uttandaraman Sundararaj
      Pages: n/a - n/a
      Abstract: Nanocomposites using copper nanowires (CuNWs) or carbon nanotubes (CNTs) as fillers with polypropylene (PP) as matrix were prepared by miscible solution mixing and precipitation method. Comparative studies on electrical conductivity and electromagnetic interference shielding properties were reported. On the conductivity curve, a plateau was found for both CuNW/PP composite and CNT/PP composite. The plateaus are located at a different concentration range for each composite type: for CuNW/PP composite, it is between 0.8 and 1.7 vol %, while for CNT/PP composite the plateau occurs in a narrower range between 0.4 and 0.6 vol %. The shielding effectiveness (SE) increases with increased concentration of fillers. CNT/PP composite has higher SE at concentrations less than 2 vol %; the two curves cross near 10 dB at this point and at concentrations higher than 2 vol %, CuNW/PP composite has higher SE. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-10T10:23:41.968034-05:
      DOI: 10.1002/aic.14646
       
  • Sensor network design for maximizing process efficiency: An algorithm and
           its application
    • Authors: Prokash Paul; Debangsu Bhattacharyya, Richard Turton, Stephen E. Zitney
      Pages: n/a - n/a
      Abstract: Sensor network design is a constrained optimization problem requiring systematic and effective solution algorithms for determining where best to locate sensors. In this work, a sensor network design (SND) algorithm is developed for maximizing plant efficiency for an estimator‐based control system while simultaneously satisfying accuracy requirements for the desired process measurements. The SND problem formulation leads to a mixed integer nonlinear programming (MINLP) optimization that is difficult to solve for large‐scale system applications. Therefore, a sequential approach is developed to solve the MINLP problem where the integer problem for sensor selection is solved using the genetic algorithm while the nonlinear programming problem including convergence of the ‘tear stream' in the estimator‐based control system is solved using the direct substitution method. The SND algorithm is then successfully applied to a large‐scale, highly integrated chemical process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-10T03:14:10.892507-05:
      DOI: 10.1002/aic.14649
       
  • Hydrodynamics, mass transfer and photocatalytic phenol selective oxidation
           reaction kinetics in fixed TiO2 microreactor
    • Authors: M. Krivec; A. Pohar, B. Likozar, G. Dražić
      Pages: n/a - n/a
      Abstract: Photocatalytic phenol dissociation was studied in a microreactor, with a TiO2 layer immobilized on the reactor inner walls. Experiments were conducted for various residence times, initial concentrations, pH values and UV light irradiation intensities. The intermediates and products (catechol, hydroquinone and resorcinol) were quantitatively investigated in order to determine the predominant reaction pathways for the investigated anatase catalyst. A 3D mathematical model was used to simulate the heterogeneous photocatalysis reaction conditions with Langmuir–Hinshelwood mechanism, considering the adsorption/desorption thermodynamic equilibria, and for kinetic parameter estimation via regression analysis. The effectiveness factor, Thiele modulus and the correction function were calculated to determine the pore diffusion effects. The value of pH had the dramatic effect of lowering the reaction rate due to the competitive adsorption of hydroxide ions and protons on the catalyst surface. A phenol conversion of 79.5% was achieved at the residence time of 7.22 min, but without total mineralization. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-07T10:03:11.572969-05:
      DOI: 10.1002/aic.14648
       
  • Air‐promoted adsorptive desulfurization of diesel fuel over
           Ti‐Ce mixed metal oxides
    • Authors: Jing Xiao; Siddarth Sitamraju, Yongsheng Chen, Shingo Watanabe, Mamoru Fujii, Michael Janik, Chunshan Song
      Pages: n/a - n/a
      Abstract: This work investigates air‐promoted adsorptive desulfurization (ADS) of commercial diesel fuel over a Ti‐Ce mixed oxide adsorbent in a flow system. The fresh/spent adsorbents were characterized using X‐ray absorption near edge structure spectroscopy. Results show that sulfoxide species are formed during air‐promoted ADS over Ti0.9Ce0.1O2 adsorbent. Adsorption selectivity of various compounds in fuel follows the order of dibenzothiophene sulfone > dibenzothiophene ≃ benzothiophene > 4‐methyldibenzothiophene > 4,6‐dimethyldibenzothiophene > phenanthrene > methylnaphthalene > fluorene > naphthalene. The high adsorption affinity of sulfoxide/sulfone is attributed to stronger Ti‐OSR2 than Ti‐SR2 interactions, resulting in significantly enhanced ADS capacity. Adsorption affinity was calculated using ab initio methods. For Ti‐Ce mixed oxides, reduced surface sites lead to O‐vacancy sites for O2 activation for oxidizing thiophenic species. Low temperature is preferred for air‐promoted ADS, and the Ti‐Ce adsorbent can be regenerated via oxidative air treatment. This study paves a new path of designing regenerable adsorbents. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-07T10:02:53.762758-05:
      DOI: 10.1002/aic.14647
       
  • An improved methodology for outlier detection in dynamic data sets
    • Authors: Shu Xu; Michael Baldea, Thomas F. Edgar, Willy Wojsznis, Terrence Blevins, Mark Nixon
      Pages: n/a - n/a
      Abstract: A time series Kalman filter (TSKF) is proposed that successfully handles outlier detection in dynamic systems, where normal process changes often mask the existence of outliers. The TSKF method combines a time series model fitting procedure with a modified Kalman filter to deal with additive outlier (AO) and innovational outlier (IO) detection problems in dynamic process data set. Compared with current outlier detection methods, the new method enjoys the following advantages: (a) no prior knowledge of the process model is needed; (b) it is easy to tune; (c) it can be applied to both univariate and multivariate outlier detection; (d) it is applicable to both on‐line and off‐line operation; (e) it cleans outliers while maintains the integrity of the original data set. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T03:18:46.156664-05:
      DOI: 10.1002/aic.14631
       
  • Modeling of continuous self‐classifying spiral jet mills part 2:
           Powder‐dependent parameters from characterization experiments
    • Authors: Derek Starkey; Cathy Taylor, Sunil Siddabathuni, Jinit Parikh, Spyros Svoronos, John Mecholsky, Kevin Powers, Ron Iacocca
      Pages: n/a - n/a
      Abstract: The milling model described in Part 1 has been expanded to a three‐level model with the addition of powder‐dependent parameter function models with simple material characterization measurements as inputs.1 This allows the determination of these parameters with minimal consumption of powder. Specifically, the powder‐dependent parameters are related to material hardness from microindentation or to a breakage measure from single‐impact milling. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the described material characterization techniques and expanded milling model. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T01:37:29.789531-05:
      DOI: 10.1002/aic.14643
       
  • A new drag correlation from fully resolved simulations of flow past
           monodisperse static arrays of spheres
    • Authors: Y. Tang; S.H.L. Kriebitzsch, E.A.J.F. Peters, M.A. van der Hoef, J.A.M. Kuipers
      Pages: n/a - n/a
      Abstract: We performed fully resolved simulations of flows past fixed assemblies of monodisperse spheres using an iterative Immersed Boundary (IB) Method, for both face‐centered‐cubic (FCC) array and random configurations. For the latter, a methodology has been applied such that the computed gas‐solid force is almost independent of the grid resolution. Simulations in this work extend the previously similar studies to a wider range of solids volume fraction (φЄ[0.1, 0.6]) and Reynolds number (ReЄ[50, 1000]). We propose a new drag correlation combining the existed drag correlations for low‐Re flows and single‐sphere flows, which fits the entire data set with an average relative deviation of 4%. This correlation is so‐far the best possible expression for the drag force in monodisperse static arrays of spheres, and is the most accurate basis to introduce the particle mobility for dynamic gas‐solid systems, such as in fluidized beds. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-06T01:15:58.54105-05:0
      DOI: 10.1002/aic.14645
       
  • A multiple radioactive particle tracking technique to investigate
           particulate flows
    • Authors: Majid Rasouli; Francois Bertrand, Jamal Chaouki
      Pages: n/a - n/a
      Abstract: Radioactive particle tracking is a nonintrusive technique that has been successfully employed to study the flow dynamics in a wide range of reactors and blenders. However, it is still limited to the tracking of only one tracer at a time. This article introduces a multiple radioactive particle tracking technique (MRPT) that can determine the trajectory of two free or restricted (attached to the same particle) moving tracers in a system. The accuracy (
      PubDate: 2014-10-06T01:15:45.07222-05:0
      DOI: 10.1002/aic.14644
       
  • Modeling of Continuous Self‐Classifying Spiral Jet Mills Part 1:
           Model Structure and Validation Using Mill Experiments
    • Authors: Derek Starkey; Cathy Taylor, Nathan Morgan, Katie Winston, Spyros Svoronos, John Mecholsky, Kevin Powers, Ron Iacocca
      Pages: n/a - n/a
      Abstract: The objective of this work is to develop a milling model for a continuous self‐classifying spiral air jet mill.1 Its foundation is a population balance model with selection and breakage distribution functions that have been related to a minimal number of mill‐dependent and powder‐dependent parameters. Initially, experimentation is required to determine the mill‐dependent parameters for a specific mill, by milling a “base” powder at multiple operating conditions. Powder‐dependent parameters can be determined from either mill experiments or from material characterization measurements that require small amounts of powder (presented in Part 2). Ultimately, the milling model presented successfully predicts the product particle size using as inputs the feed particle size distribution and mill operating conditions. Three crystalline powders, sodium bicarbonate, lactose monohydrate, and sucrose, have been used to test the proposed milling model. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-04T03:29:30.11227-05:0
      DOI: 10.1002/aic.14642
       
  • Novel Co‐Mn‐O nanosheet catalyst for CO preferential oxidation
           toward hydrogen purification
    • Authors: Zhongkui Zhao; Jinhan Lin, Guiru Wang, Turghun Muhammad
      Pages: n/a - n/a
      Abstract: Co‐Mn‐O composite oxide nanosheet catalyst was successfully prepared by using a facile urea‐assisted one‐step hydrothermal method in the absence of organic or organic templating reagent. Co‐Mn‐O nanosheet catalyst was optimized by varying hydrothermal process parameters such as molar ratio of Co‐Mn to urea, hydrothermal temperature, and hydrothermal time. Various characterization techniques including scanning electron microscopy, X‐ray diffraction, nitrogen adsorption, X‐ray photoelectron spectroscopy, Raman spectroscopy and H2 temperature‐programmed reduction were employed to reveal the relationship between catalyst nature and catalytic performance in CO preferential oxidation in excess H2. The developed Co‐Mn‐O nanosheet catalyst have demonstrated much superior catalytic performance to Co‐Mn‐O nanoparticle, particularly in the low temperature range, and 100% CO conversion over the developed Co‐Mn‐O nanosheet can be achieved in temperature range of 50 to 150 oC at 10,000 ml g‐1 h‐1 of gas hourly space velocity in the standard feed. Furthermore, the almost complete CO removal over Co‐Mn‐O nanosheet at 125 oC of low temperature with 94.9% selectivity can be achieved even in the simulated reformed gas. The excellent catalytic performance is ascribed to nanosheet morphology, more surface Co3+, smaller average crystallite size, higher reducibility, and strong Co‐Mn interaction. Catalytic stability investigation indicates the developed nanostructured catalyst exhibits high catalytic stability for CO PROX reaction in simulated gas. The developed Co‐Mn‐O nanosheet catalyst can be a potential candidate for catalytic elimination of trace CO from H2‐rich gas for PEMFC applications. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-10-04T03:09:13.155962-05:
      DOI: 10.1002/aic.14641
       
  • Protic ionic liquids for the selective absorption of H2S from CO2:
           Thermodynamic analysis
    • Authors: Kuan Huang; Xiao‐Min Zhang, Yun Xu, You‐Ting Wu, Xing‐Bang Hu
      Pages: n/a - n/a
      Abstract: The solubilities of H2S and CO2 in four protic ionic liquids (PILs) ‐ methyldiethanolammonium acetate, methyldiethanolammonium formate, dimethylethanolammonium acetate and dimethylethanolammonium formate were determined at 303.2~333.2K and 0~1.2bar. It is shown PILs have higher absorption capacity for H2S than normal ILs and the Henry's law constants of H2S in PILs (3.5~11.5bar at 303.2K) are much lower than those in normal ILs. In contrast, the solubility of CO2 in PILs is found to be a magnitude lower than that of H2S, implying these PILs have both higher absorption capacity for H2S and higher ideal selectivity of H2S/CO2 (8.9~19.5 at 303.2K) in comparison with normal ILs. The behavior of H2S and CO2 absorption in PILs is further demonstrated based on thermodynamic analysis. The results illustrate that PILs are a kind of promising absorbents for the selective separation of H2S/CO2 and believed to have potential use in gas sweetening. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T07:03:00.090805-05:
      DOI: 10.1002/aic.14634
       
  • APOD‐based control of linear distributed parameter systems under
           sensor/controller communication bandwidth limitations
    • Authors: Davood Babaei Pourkargar; Antonios Armaou
      Pages: n/a - n/a
      Abstract: The synthesis of a model‐based control structure for general linear dissipative distributed parameter systems (DPSs) is explored in this manuscript. Discrete‐time distributed state measurements (called process snapshots) are employed by a continuous‐time regulator to stabilize the process. The main objective of this paper is to identify a criterion to minimize the communication bandwidth between sensors and controller (snapshots acquisition frequency) using linear systems analysis and still achieve closed‐loop stability. This objective is addressed by adding a modeling layer to the regulator. Theoretically DPSs can be well described by low dimensional ODE models when represented in functional spaces; practically, the model accuracy hinges on finding basis functions for these spaces. Adaptive proper orthogonal decomposition is employed to identify statistically important basis functions and establish locally accurate reduced order models which are then used in controller design. The proposed approach is successfully applied towards thermal regulation in a tubular chemical reactor. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:34:05.396465-05:
      DOI: 10.1002/aic.14640
       
  • Kinetic Study of the Competitive Hydrogenation of Glycolaldehyde and
           Glucose on Ru/C with or without AMT
    • Authors: Junying Zhang; Baolin Hou, Aiqin Wang, Zhenlei Li, Hua Wang, Tao Zhang
      Pages: n/a - n/a
      Abstract: The competitive hydrogenation of glycolaldehyde and glucose over 1%Ru/C catalyst was studied in a batch reactor at 373‐403 K and 6 MPa hydrogen pressure, with or without the presence of ammonium metatungstate (AMT). It was found that the presence of AMT retarded significantly the hydrogenation of both aldoses, and this suppressing effect was more pronounced on the glucose hydrogenation. The hydrogenation of glycolaldehyde occurred always preferentially to the glucose hydrogenation, with or without the presence of AMT. The kinetic data in the absence of AMT were well modeled based on Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) kinetics assuming the surface reaction being rate‐determining and non‐competitive adsorption of dissociatively chemisorbed hydrogen and aldose. However, in the presence of AMT, the complexing between AMT and aldose and the strong adsorption of AMT on Ru surface must be considered in the development of new kinetic model. The as‐modified model described the data satisfactorily. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:33:12.979792-05:
      DOI: 10.1002/aic.14639
       
  • Kinetic modeling of Fe‐BEA as NH3‐SCR catalyst – Effect
           of Phosphorous
    • Authors: Soran Shwan; Jonas Jansson, Louise Olsson, Magnus Skoglundh
      Pages: n/a - n/a
      Abstract: The focus of this work is to investigate whether a previously developed micro‐kinetic deactivation model for hydrothermally treated Fe‐BEA as NH3‐SCR catalyst can be applied to describe chemical deactivation of Fe‐BEA due to phosphorous exposure. The model describes the experiments well for Fe‐BEA before and after phosphorous exposure by decreasing the site density, representing deactivation of sites due to formation of metaphosphates blocking the active iron sites, while the kinetic parameters are kept constant. Furthermore, the results show that the activity for low‐temperature SCR is very sensitive to loss of active monomeric iron species due to phosphorous poisoning compared to high‐temperature SCR. Finally, the ammonia inhibition simulations show that exposure to phosphorous may affect the internal transport of ammonia between ammonia storage sites buffering the active iron sites which results in a lower SCR performance during transient conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-30T03:31:23.081017-05:
      DOI: 10.1002/aic.14638
       
  • Development of a Fluidized Bed Thermo‐Gravimetric Analyzer
    • Authors: Said Samih; Jamal Chaouki
      Pages: n/a - n/a
      Abstract: A new fluidized bed thermo‐gravimetric analyzer (FB‐TGA) was developed that introduces two major particularities: the pseudo variation of the weight of the reactor and the special strategy for gas flow rate adjustment according to temperature. A momentum balance was performed on the reactor and the pseudo variation of the reactor weight was evaluated by measuring the pressure drop through the gas distributor and filter. The real weight loss of the reactor was obtained by subtracting the pseudo variation of the weight from the total weight loss measured by the load cell. In addition, a special program for the gas flow rate as a function of temperature was developed and used; so the minimum fluidization regime is maintained throughout all of the experiments. The validation test of the Fluidized Bed TGA was carried out on calcium hydroxide decomposition and the results were compared with those obtained from the conventional TGA. Diffusion control was suppressed by the application of the Fluidized Bed TGA, which was confirmed by the X‐Ray Diffraction (XRD) analysis on the treated samples. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-27T03:34:36.379465-05:
      DOI: 10.1002/aic.14637
       
  • Spouting behaviors of binary mixtures of cylindroid and spherical
           particles
    • Authors: Xuejiao Liu; Wenqi Zhong, Xiaofeng Jiang, Baosheng Jin
      Pages: n/a - n/a
      Abstract: Spouting behaviors of cylindroid and spherical particles in a spouted bed are experimentally investigated. The characteristics of flow pattern and pressure drop of the binary mixtures are figured out and three kinds of cylindroid particles with different sizes and shapes are involved in experiments to discuss effects of particle size and shape on the spouting behaviors in beds. The emphasis is laid on the influence of the volume fraction of cylindroid particles, Xc, on the spouting phenomena, including the total pressure drop, the minimum spouting velocity and fountain height. Results show that, the shapes and sizes of cylindroid particles, mainly including equi‐volume diameter and aspect ratio, significantly affect the spouting behaviors. There is a maximum volume fraction, Xc,max, for each kind of cylinders to maintain the stable fountain at a certain gas velocity. With the same gas velocity, Xc,max is lower for the cylinders with higher aspect ratio. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-26T03:17:39.249733-05:
      DOI: 10.1002/aic.14636
       
  • Systematic study on heat transfer and surface hydrodynamics of a vertical
           heat tube in a fluidized bed of FCC particles
    • Authors: Xiuying Yao; Xiao Han, Yongmin Zhang, Chunxi Lu
      Pages: n/a - n/a
      Abstract: Bed‐to‐wall heat transfer properties of a vertical heat tube in a fluidized bed of fine FCC particles are measured systematically using a specially designed heat tube. Two important surface hydrodynamic parameters, i.e. the packet fraction (δpa) and mean packet residence time (τpa) based on the packet renewal theory, are determined by an optical fiber probe and a data processing method. The experimental results successfully reveal the axial and radial profiles of heat transfer coefficient, the effects of superficial gas velocity and static bed height on heat transfer coefficient, most of which can be explained successfully by the measured τpa, an indicator of packet renewal frequency. τpa is found to play a more dominant role than δpa on bed‐to‐wall heat transfer. With a fitted correction factor, the modified Mickley & Fairbanks model is able to predict the heat transfer coefficients with enough accuracy based on the determined packet parameters. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-26T03:16:27.713727-05:
      DOI: 10.1002/aic.14635
       
  • Role of block copolymer on the coarsening of morphology in polymer blend:
           Effect of micelles
    • Authors: Chongwen Huang; Wei Yu
      Pages: n/a - n/a
      Abstract: The reactive compatibilization of polystyrene/ ethylene‐α‐octene copolymer (PS/POE) blend via Friedel‐Crafts alkylation reaction was investigated by rheology and electron microscope. It was found that the graft copolymer formed from interfacial reaction reduced the domain size and decreased the coarsening rate of morphology. The reduction of the interfacial tension is very limited according to the mean field theory even assuming that all block copolymer stays on the interface. With the help of self‐consistent flied theory and rheological constitutive models, the distribution of graft copolymer was successfully estimated. It was found that large amount of copolymer had detached from the interfaces and formed micelles in the matrix. Both the block copolymer micelles in matrix and the block copolymers at the interface contribute to the suppression of coarsening in polymer blend, but play their roles at different stages of droplet coalescence. In droplet morphology, the micelles mainly hinder the approaching of droplets. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-25T04:46:23.069886-05:
      DOI: 10.1002/aic.14633
       
  • Reaction Kinetics and Mechanism of Catalyzed Hydrolysis of Waste PET Using
           Solid Acid Catalyst in Supercritical CO2
    • Authors: Xue‐Kun Li; Hui Lu, Wen‐Ze Guo, Gui‐Ping Cao, Hong‐Lai Liu, Yun‐Hai Shi
      Pages: n/a - n/a
      Abstract: Hydrolysis of waste PET using solid acid catalyst in SCCO2 is presented in this work for the first time. The mechanism of PET chains scission was proved to be a combination of chain end and random chain scission by FT‐IR and titration analysis. A new reaction kinetics model of PET hydrolysis in SCCO2 was set up by introducing the Arrhenius equation into an ordinary reaction rate equation, the frequency factor and apparent activation energy were expressed in terms of temperature and CO2 pressure, respectively. With this reaction kinetics model, the effects of temperature, and pressure were investigated. An interesting mechanism was proposed to describe the reaction process that both water molecules and hydroniums were carried and penetrated into the amorphous regions of the swollen PET by SCCO2, subsequently hydrolysis reaction preferentially took place in the amorphous regions of both surface and bulk of PET matrix. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-24T01:54:52.62141-05:0
      DOI: 10.1002/aic.14632
       
  • Integrated solvent and process design exemplified for a Diels‐Alder
           reaction
    • Authors: Teng Zhou; Kevin McBride, Xiang Zhang, Zhiwen Qi, Kai Sundmacher
      Pages: n/a - n/a
      Abstract: A new kind of solvent descriptor obtained from quantum chemical calculations is introduced. Group contributions to each solvent descriptor are regressed for 71 UNIFAC groups. A reaction kinetic model is built by correlating a set of experimentally determined reaction rate constants in various solvents with the corresponding theoretical solvent descriptors. Based on the kinetic model and the developed group contribution method, a computer‐aided molecular design (CAMD) problem is formulated and optimal solvents to achieve highest reaction rates are identified. For considering the multiple and complicated effects of solvents on a chemical process, an integrated solvent and process design is performed. Solvent molecular structures and process operations are simultaneously optimized by the formulation and solution of a mixed integer nonlinear program (MINLP). The proposed design methodology is exemplified for a selected Diels‐Alder reaction. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-22T10:05:45.556199-05:
      DOI: 10.1002/aic.14630
       
  • Effect of Particle Size on Flow and Mixing in a Bladed Granular Mixer
    • Authors: Avik Sarkar; Carl R. Wassgren
      Pages: n/a - n/a
      Abstract: A number of studies have modeled flow and mixing of granular materials using the discrete element method (DEM). In an attempt to reduce computational costs, many of these DEM studies model particles larger than the actual particle size without investigating the implications of this assumption. Using DEM, the influence of the modeled particle size on flow and mixing in a bladed granular mixer is studied. The predicted flow microdynamics, including mixing rates, are strongly dependent on the particle diameter. The effect of particle size on macroscopic advective flow also is significant, particularly for dilute flow regions. These results suggest that the influence of particle size needs to be taken into consideration when using larger particles in DEM mixing simulations. To guide scale‐up efforts, particle‐size‐based scaling relationships for several key flow measurements are presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-19T03:07:17.654639-05:
      DOI: 10.1002/aic.14629
       
  • Engineering Acidithiobacillus ferrooxidans growth media for enhanced
           electrochemical processing
    • Authors: Xiaozheng Li; Roel Mercado, Sarah Berlinger, Scott Banta, Alan C. West
      Pages: n/a - n/a
      Abstract: The chemolithoautotroph A. ferrooxidans has been proposed as a potential electrofuel synthetic platform, and its growth medium is engineered to increase its conductivity and energy density, thereby improving viability of the process. The ion V3+ is used as an indirect electron supplier together with Fe2+ to grow A. ferrooxidans to increase the energy density of the medium, overcoming the Fe3+ solubility limit. A medium containing 10 mM Fe2+ with 60 mM V3+ was able to support cell growth to a final cell concentration very similar to medium of 70 mM Fe2+. Integration of the biological process with an electrochemical reactor requires, for economical operation, a medium with high ionic conductivity. This is achieved by the addition of salt, and Mg2+ was found to be least toxic to the bacterium. A concentration of 500 mM Mg2+ is optimal considering constraints on bacterial growth and electrochemistry. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T03:48:54.727058-05:
      DOI: 10.1002/aic.14628
       
  • A General and Robust Approach for Defining and Solving Microkinetic
           Catalytic Systems
    • Authors: Gabriel S. Gusmão; Phillip Christopher
      Pages: n/a - n/a
      Abstract: Recent approaches for the rational design of heterogeneous catalysts have relied on first‐principles based microkinetic modeling to efficiently screen large phase spaces of catalytic materials for optimal activity and selectivity. Microkinetic modeling allows the calculation of catalytic rate and selectivity under a given set of conditions without a priori assumptions of rate or selectivity controlling steps by simultaneously solving non‐linear algebraic equations comprising species mass balances bound by the pseudo steady state approximation. We introduce a general approach to define and solve microkinetic systems that relies solely on its stoichiometric matrix and kinetic parameters of considered reaction steps. Our approach relies on linearization of the microkinetic system, enabling analytical calculation of system derivatives for use in quasi‐Newton solution schemes that exhibit excellent robustness and efficiency with minimal dependence on initial conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-17T02:00:55.601826-05:
      DOI: 10.1002/aic.14627
       
  • Introducing vapor recompression mechanism in heat integrated distillation
           column (HIDiC): Impact of internal energy driven intermediate and bottom
           reboiler
    • Authors: Bandaru Kiran; Amiya K. Jana
      Pages: n/a - n/a
      Abstract: This work proposes a novel combination of internally heat integrated distillation column (HIDiC) and vapor recompression column (VRC) with intermediate reboiler (IR). Supplying heat at the highest temperature point (i.e., column bottom) of the VRC scheme is not thermodynamically favorable and therefore, we aim to install the IR for better distribution of heat along the column length, thereby reducing the compressor work. Introducing IR in the combined HIDiC‐VRC system, the present work formulates an open‐loop variable manipulation policy to evaluate the comparative impact of internal and external heat sources on bottom liquid reboiling. With internal energy driven bottom reboiler, we further investigate the hybrid HIDiC‐VRCIR column with proposing the two modes of compressor arrangement, namely parallel and series. Finally, a multicomponent distillation system is exampled to show the promising potential of the proposed HIDiC‐VRCIR configurations in improving the energetic and economic performance over the HIDiC‐alone and HIDiC‐VRC schemes with reference to a conventional standalone column. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T11:20:40.502851-05:
      DOI: 10.1002/aic.14620
       
  • 1H‐ and 13C‐NMR Spectroscopic Study of Chemical Equilibria in
           the System Acetaldehyde + Water
    • Authors: Andreas Scheithauer; Thomas Grützner, Christiaan Rijksen, Daniel Zollinger, Erik von Harbou, Werner R. Thiel, Hans Hasse
      Pages: n/a - n/a
      Abstract: Acetaldehyde is an important intermediate in the chemical industry and often used in mixtures with water. These mixtures are reactive multicomponent systems, as acetaldehyde forms oligomers with water. Quantitative studies of the resulting speciation are scarce in the literature and limited to the formation of the smallest oligomer, ethane‐1,1‐diol. Therefore, in the present work, a comprehensive study of chemical equilibria in mixtures of acetaldehyde and water was carried out by quantitative 1H‐ and 13C‐NMR spectroscopy. The study covers temperatures between 275 and 338 K and overall acetaldehyde mole fractions between about 0.05 and 0.95 mol/mol. The peak assignment is given for both the 1H‐ and 13C‐NMR spectra. From the speciation data, obtained from the peak area fractions, numbers for the chemical equilibrium constants of the oligomer formation are obtained and a correlation is presented. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T04:06:19.379465-05:
      DOI: 10.1002/aic.14623
       
  • Kinetics of formation of oil‐in‐water emulsions using in situ
           rheo‐optical measurements
    • Authors: Rudy Covis; Christophe Baravian, Emmanuelle Marie, Alain Durand
      Pages: n/a - n/a
      Abstract: The kinetics of mechanical emulsification in vane geometry was investigated using an original rheo‐optic device. Hexadecane‐in‐water micronic emulsions were prepared using a nonionic polymeric surfactant (Brij700®) as stabilizer. The viscosity of aqueous phase was adjusted using a commercial viscosifier (Emkarox®) which ensured Newtonian behavior to the continuous phase. The influences of two variables (rotational speed and oil volume fraction) on the kinetics of droplet fragmentation were examined in detail. Rotational speed was varied between 50 and 100 rad.s‐1 and had a strong effect on the kinetics of emulsion formation which was discussed on the basis of droplet fragmentation by shear forces. On the contrary, oil volume fraction (between 20 and 60 % v/v) showed no marked effect, which appeared as an important result for scale up considerations. A theoretical description of fragmentation mechanism was proposed and experimental results were compared to calculated values. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-16T03:58:15.289281-05:
      DOI: 10.1002/aic.14626
       
  • The generation of hydroxyl radicals by hydrogen peroxide decomposition on
           FeOCl/SBA‐15 catalysts for phenol degradation
    • Authors: Xue‐jing Yang; Peng‐fei Tian, Xiao‐man Zhang, Xin Yu, Ting Wu, Jing Xu, Yi‐fan Han
      Pages: n/a - n/a
      Abstract: Iron oxychloride (FeOCl) supported on mesoporous silica (SBA‐15), as a Fenton‐like solid catalyst for phenol degradation, showed supreme activity for production of hydroxyl radical (HO·) by H2O2 decomposition, and the generation capacity was comparable to the conventional Fenton reagent (Fe2++H2O2). The structure of FeOCl was characterized with multi spectroscopies. The generation of HO· species during the reaction was detected using 5,5‐ dimethyl‐1‐pyrroline N‐ oxide (DMPO) trapped electron paramagnetic resonance (EPR). Furthermore, the kinetics in detail was driven for the creation and diffusion of HO· by H2O2 decomposition over FeOCl, which follows a first‐order rate through a two‐step reaction. With the combination of the catalyst structure and kinetic parameters, the plausible mechanism for H2O2 decomposition during the oxidative degradation of phenol was rationalized. As a Fenton‐like solid catalyst, FeOCl/SBA‐15 is a promising alternative for the removal of low‐level organic contaminates from water. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-12T12:13:28.25-05:00
      DOI: 10.1002/aic.14625
       
  • Continuum approximation of large reaction mixtures in reactors with
           backmixing
    • Authors: Teh C. Ho; Benjamin S. White
      Pages: n/a - n/a
      Abstract: The growing need to produce ultra‐clean fuels from hydrocarbon mixtures such as petroleum fractions and residues has put increasing pressure on refiners to achieve deep conversions. It is imperative to be able to predict the behavior of such mixtures at high conversions as functions of their properties and reactor type. To this end, treating the reaction mixture as a continuum greatly simplifies the analysis and modeling of the conversion process. However, the continuum approximation can become invalid at very high conversions. Previously, we examined the validity of the approximation for various reactions in plug flow reactors. The present work develops validity conditions for first‐order reaction mixtures in reactors with different mixing intensities. In general, backmixing widens the range of validity. In certain cases the continuum approximation is valid at arbitrarily high conversions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T09:47:24.673548-05:
      DOI: 10.1002/aic.14624
       
  • Quality assurance of Chinese herbal medicines: Procedure for
           multiple‐herb extraction
    • Authors: Yeuk T. Lau; Na Chen, David T. W. Lau, Kam M. Ko, Ka M. Ng, Ping C. Leung, Christianto Wibowo
      Pages: n/a - n/a
      Abstract: A quality assurance (QA) procedure for multiple‐herb extraction, which takes into account the existence of common chemical markers and multiple‐herb‐extraction effects, has been developed for producing Chinese herbal medicines (CHMs) of consistent quality. The experimental method for determining related correlation function of the multiple‐herb‐extraction effect was designed. A systematic solution strategy was also developed to appropriately decompose the multiple‐herb extraction system into several subsystems for obtaining solution(s) and determining the overall behavior of the system. An example of quality assurance of Danshen‐Gegen (DG) decoction was used to demonstrate the QA procedure. An H9c2 cell assay was used to test the efficacy of consistent quality DG decoctions prepared by different herb combinations with different material costs of herbs. It was observed that a multiple‐herb‐extraction effect was present in the aqueous extraction of Danshensu and this effect was depended on the extraction solvent. The possible mechanism of this multiple‐herb‐extraction effect in the aqueous DG extraction was speculated to be the change of initial pH value of the aqueous extraction solvent by an unknown component from Gegen. The experimental chemical marker concentrations fell within ±10% of the specified chemical marker compositions by using the amount of herb from each herb class as predicted by the QA model. Furthermore, an H9c2 cell assay was used to test the efficacy of three consistent quality DG extracts, which were produced by different herb combinations with different material costs of herbs. The results showed that the three DG extracts provided consistent biological efficacy against menadione‐induced toxicity. This study extended a recently developed QA procedure of single‐herb extraction to multiple‐herb extraction. It provides a solution of quality assurance in extraction, which is one of the most important unresolved problems in the modernization of traditional Chinese medicines. With this modified model and the companion experiments, the amount of herbs needed from different quality classes to produce a multiple‐herb formula CHM product decoction with consistent quality can be exactly determined. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:34:42.636755-05:
      DOI: 10.1002/aic.14619
       
  • Multi‐scale modeling of protein adsorption and transport in
           macroporous and polymer‐grafted ion exchangers
    • Authors: Joseph E. Basconi; Giorgio Carta, Michael R. Shirts
      Pages: n/a - n/a
      Abstract: A multi‐scale model is presented to elucidate protein adsorption and transport behaviors in ion‐exchange chromatography (IEC) adsorbent particles that have either an open pore structure or charged dextran polymers grafted into the pores. Molecular dynamics (MD) simulation is used to determine protein diffusion and partitioning in different regions of the adsorbent pore, and these outputs are used in numerical simulations of mass transfer to determine the intraparticle protein concentration profile and the mass transfer rate. Modeling results indicate that, consistent with experimental observations, protein transport can be faster in the polymer‐grafted material compared to the open pore case. This occurs when favorable partitioning of protein into the polymer‐filled pore space is combined with relatively high protein mobility within this region. The modeling approach presented here should be applicable to proteins and adsorbents with different properties, and could help elucidate the factors that control adsorption and transport in various IEC systems. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:30:19.56178-05:0
      DOI: 10.1002/aic.14621
       
  • Number density of turbulent vortices in the entire energy spectrum
    • Authors: Farideh Ghasempour; Ronnie Andersson, Donald J. Bergstrom, Bengt Andersson
      Pages: n/a - n/a
      Abstract: In coalescence and break‐up modeling, vortex number density and size distributions of turbulent vortices are required in order to calculate the rate of interaction between continuous and dispersed phases. Existing number density models are only valid for the inertial subrange of the energy spectrum and no model of the vortex number density, valid for the entire energy spectrum, is available. In the present study, the number density of the turbulent vortices were studied and modeled for the entire energy spectrum including the dissipative, inertial and energy containing subranges. It was observed that the new number density model depends on vortex size, local turbulent kinetic energy and dissipation rate. Moreover, the new number density model was validated by the number density distributions quantified in a turbulent pipe flow. The turbulent vortices of the pipe were identified and labeled using a vortex‐tracking algorithm that was developed recently by the authors. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-11T08:26:23.384187-05:
      DOI: 10.1002/aic.14622
       
  • Phenomenological model‐based analysis of lithium batteries.
           Discharge, charge, relaxation times studies and cycles analysis
    • Authors: E.R. Henquín; P.A. Aguirre
      Pages: n/a - n/a
      Abstract: This work addresses the operation of lithium ion batteries in discharge and charge processes. A simple phenomenological model is developed in order to predict all variables values. A set of algebraic and differential equations is derived taking into account salt and Lithium balances in electrodes, in the separator, and in particles. Balances are developed for finite volumes and appropriate average values of several variables such as concentrations, current densities, and electrochemical reaction rates are introduced. Definitions of current densities as volume fraction functions are critical issues in the computations. Experimental values taken from the literature for discharge processes are predicted very accurately. Constant salt concentration in the separator can be assumed and consequently the model can be analytically solved. Charge and discharge times, initial cell capacity, lost capacity and relaxation times are easily estimated from simple equations and cell parameters. The limiting processes taking place during cell discharge can be determined. Energy efficiency and capacity usage are quantified for cycles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-08T07:20:21.635278-05:
      DOI: 10.1002/aic.14618
       
  • Experimental study of oscillation behaviors in confined impinging jets
           reactor under excitation
    • Authors: Wei‐Feng Li; Wen‐Wei Qian, Guang‐Suo Yu, Hai‐Feng Liu, Fu‐Chen Wang
      Pages: n/a - n/a
      Abstract: Dynamic behaviors in a three‐dimensional confined impinging jets reactor (CIJR) under excitation were experimentally studied by a flow visualization technique at 75≤Re≤150. The effects of inlet Reynolds numbers (Re), excitation frequencies and excitation amplitudes on the oscillation behaviors in CIJR have been investigated by a Particle Image Velocimetry (PIV) and a high‐speed camera. Results indicate that the excitation in the inflow of the opposed jets can induce periodic oscillation of the impingement plane along the axis, whose oscillation frequency is equal to the excitation frequency. At Re≤100, the induced axial oscillation can further cause a deflective oscillation with a frequency nearly equal to the excitation, and the scale of the vortex in the impingement plane is well regulated by the excitation frequency. At Re=150, the excitation of amplitude less than 20% has insignificant effect on the deflective oscillation existing in CIJR. A semiempirical formula has been proposed to predict the oscillation amplitude of the impingement plane in CIJR under excitation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-05T04:38:52.435156-05:
      DOI: 10.1002/aic.14617
       
  • Synthesis of sustainable integrated biorefinery via reaction pathway
           synthesis: Economic, incremental enviromental burden and energy assessment
           with multi‐objective optimization
    • Authors: Viknesh Andiappan; Andy S. Y. Ko, Veronica W. S. Lau, Lik Yin Ng, Rex T. L. Ng, Nishanth G. Chemmangattuvalappil, Denny K. S. Ng
      Pages: n/a - n/a
      Abstract: With the increasing attention toward sustainable development, biomass has been identified as one of the most promising sources of renewable energy. In order to convert biomass into value‐added products and energy, an integrated processing facility, known as an integrated biorefinery is needed. To date, various biomass conversion systems such as gasification, pyrolysis, anaerobic digestion, fermentation, etc. are well established. Due to a large number of technologies available, systematic synthesis of a sustainable integrated biorefinery which simultaneously considers economic performance, environmental impact and energy requirement is a challenging task. In order to address this issue, multi‐objective optimization approaches are used in this work to synthesize a sustainable integrated biorefinery. In addition, a novel approach (incremental environmental burden) to assess the environmental impact for an integrated biorefinery is presented. To illustrate the proposed approach, a palm‐based biomass case study is solved. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-05T04:31:36.584805-05:
      DOI: 10.1002/aic.14616
       
  • Evolving trends in chemical engineering education
    • Authors: Arvind Varma; Ignacio Grossmann
      Pages: n/a - n/a
      PubDate: 2014-09-04T07:36:27.981856-05:
      DOI: 10.1002/aic.14613
       
  • Dynamic CO2 adsorption performance of internally cooled silica supported
           poly(ethylenimine) hollow fiber sorbents
    • Authors: Yanfang Fan; Ying Labreche, Ryan P. Lively, Christopher W. Jones, William J. Koros
      Pages: n/a - n/a
      Abstract: The dynamic adsorption behavior of CO2 under both non‐isothermal and nearly isothermal conditions in silica supported poly(ethylenimine) (PEI) hollow fiber sorbents (Torlon®‐S‐PEI) is investigated in a rapid temperature swing adsorption (RTSA) process. A maximum CO2 breakthrough capacity of 1.33 mmol/g‐fiber (2.66 mmol/g‐silica) is observed when the fibers are actively cooled by flowing cooling water in the fiber bores. Under dry CO2 adsorption conditions, heat released from the CO2‐amine interaction increases the CO2 breakthrough capacity by reducing the severity of the diffusion resistance in the supported PEI. This internal resistance can also be alleviated by prehydrating the fiber sorbent with a humid N2 feed. The CO2 breakthrough capacity of prehydrated fibers is adversely affected by the release of the adsorption enthalpy (unlike the dry fibers); however, active cooling of the fiber results in a constant CO2 breakthrough capacity even at high CO2 delivery rates (i.e., high adsorption enthalpy delivery rates). In full RTSA cycles, a purity of 50% CO2 is achieved and the adsorption enthalpy recovery rate can reach ˜ 72%. Studies on the cyclic stability of uncooled fiber sorbents in the presence of SO2 and NO contaminants indicate that exposure to NO at 200 ppm over 120 cycles does not lead to a significant degradation of the sorbents, but SO2 exposure at a similar high concentration of 200 ppm causes 60% loss in CO2 breakthrough capacity after 120 cycles. A simple amine re‐infusion technique is successfully demonstrated to recover the adsorption capacity in poisoned fiber sorbents after deactivation by exposure to impurities such SO2. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:36:31.449898-05:
      DOI: 10.1002/aic.14615
       
  • Experimental study on the reaction rate of a second‐order chemical
           reaction in a planar liquid jet
    • Authors: T. Watanabe; Y. Sakai, K. Nagata, O. Terashima
      Pages: n/a - n/a
      Abstract: Instantaneous concentrations of reactive species are simultaneously measured in a planar liquid jet with a second‐order chemical reaction A + B → R in order to investigate the statistical properties of the chemical reaction rate and the validity of models which have been proposed for concentration correlation. The jet flow contains the reactant A and the ambient flow contains the reactant B. The results show that the concentration correlation of the reactants makes a negative contribution to the mean reaction rate, and this contribution is important in the downstream direction. The concentration correlation changes owing to the chemical reaction. The effects of the chemical reaction on the concentration correlation change with the flow location and the Damköhler number. The concentration correlation predicted by the Toor’s model and the three‐environment (3E) model are compared with the experimental results. The results show that these models fail to accurately estimate the concentration correlation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:25:43.51534-05:0
      DOI: 10.1002/aic.14610
       
  • Facile fabrication of spherical architecture of Ni/Al layered double
           hydroxide based on in situ transformation mechanism
    • Authors: Fazhi Zhang; Yue Zhang, Caili Yue, Rong Zhang, Yanmin Yang
      Pages: n/a - n/a
      Abstract: Spherical architectures of nickel‐aluminum layered double hydroxide (NiAl‐LDH) with hydrotalcite‐like nanoflakes as building blocks were facilely fabricated by precipitation reaction in aqueous solution without any surfactants and organic solvents. Growth of such unique structure undergoes preorganization of primary nanospheres of colloidal amorphous aluminum hydroxide (AAH) in solution, followed by nucleation and crystallizaion of LDH from exterior to interior of AAH spheres by an in situ transformation mechanism. The structure and morphology of LDH spheres depend on both starting raw materials and synthetic parameters including reaction time, reaction temperature and aqueous ammonia dosage. NiAl‐LDH sphere as positive electrode material delivers improved rechargeable and discharge‐capacity, with the highest discharge capacity of 173 mAh g‐1 at a current density of 30 mA g‐1 within a potential range from ‐0.1 to 0.45 V in 10 mol L‐1 KOH solution, due to the faster diffusion processes in the spherical architecture than the powder sample. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:45.291152-05:
      DOI: 10.1002/aic.14609
       
  • Wet dispersion mechanism of fine aggregates in multiphase flow with solid
           beads under simple shear
    • Authors: Daisuke Nishiura; Atsuko Shimosaka, Hide Sakaguchi
      Pages: n/a - n/a
      Abstract: Clarifying the disintegration mechanism of aggregates in multiphase fluid flow coupled with beads and particulates is important for the optimum design of a wet dispersion process using a stirred media mill. Thus, we develop a numerical method for simulating multiphase flow with beads and particulates using a discrete element method and computational fluid dynamics, and we employ the four‐way coupling simulation to study the fluid‐bead‐particulate‐coupled phenomenon that occurs in a simple shear box. The results show that the dominant force causing aggregate disintegration is the fluid force, rather than the bead contact force, because aggregates rarely collide with beads, contact force of which is too small to disintegrate aggregates. Furthermore, aggregates with strong aggregation force are effectively disintegrated by the fluid flow with a dominant high pure‐shear rate induced near the bead surfaces by the expansive force, rather than the compressive force. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:24:31.247714-05:
      DOI: 10.1002/aic.14614
       
  • Natural Giesekus fluids: Shear and extensional behavior of food gum
           solutions in the semi‐dilute regime
    • Authors: M.D. Torres; B. Hallmark, L. Hilliou, D.I. Wilson
      Pages: n/a - n/a
      Abstract: The shear and extensional behavior of two aqueous gum solutions, namely (i) 1‐20 g/L guar gum 1and (ii) κ/ι‐hybrid carrageenan solutions (5‐20 g/L), are shown to exhibit Giesekus‐fluid behaviour when in the semi‐dilute regime. In this regime a common set of Giesekus fluid parameters described both shear and extensional behavior. A new analytical result describing the extension of a Giesekus fluid in the filament stretching geometry is presented. This also gave reasonable predictions of the Trouton ratio. Higher concentration guar solutions, in the entangled regime, yielded different Giesekus fluid parameters for extension to those for simple shear. The extensional data for all concentrations of both gums collapsed to a common functional form, similar to that reported for cake batters2; the limits of the new filament thinning expression provide insight into this behaviour. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T03:05:38.926095-05:
      DOI: 10.1002/aic.14611
       
  • Influence of unsteady mass transfer on dynamics of rising and sinking
           droplet in water: Experimental and CFD study
    • Authors: Abhijit Rao; Rupesh K Reddy, Kalliat T Valsaraj, Krishnaswamy Nandakumar, Shashank Pandey, C. L. Wu
      Pages: n/a - n/a
      Abstract: Experimental and numerical investigations were conducted to study the effect of unsteady mass transfer on the dynamics of an organic droplet released in quiescent water. The situation is important and relevant to deep sea oil spill scenario. The droplet contains two components, one is heavier (immiscible) than water and other is lighter (miscible). When released, with an initial mixture density (890‐975 kg/m3) lower than that of surrounding water, droplet rises in the column. The mass transfer of lighter solute component into water causes the droplet density to increase and droplet sinks when the density exceeds that of water. A mass transfer correlation accounting for the loss of the solute, based on Reynolds, Grashoff and Schmidt numbers was developed. A 2D axisymmetric CFD model accounting for species transport was developed to emulate the experimental observations. The study also helped in identifying dominant mass transfer mechanisms during different stages of droplet motion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-04T02:56:12.35339-05:0
      DOI: 10.1002/aic.14612
       
  • Orbitally Shaken Bioreactors ‐ Viscosity effects on flow
           characteristics
    • Authors: Andrea Ducci; Weheliye Hashi Weheliye
      Pages: n/a - n/a
      Abstract: Phase resolved PIV measurements were carried out to assess the flow dynamics occurring in orbitally shaken bioreactors of cylindrical geometry when working fluids of increasing viscosity are considered. Study of the phase‐resolved flow characteristics allowed to built a Re‐Fr map, where four quadrants associated to different flow regimes are identified: in‐phase toroidal vortex (low Fr, high Re), out‐of‐phase precessional vortex (high Fr, high Re), in‐phase single vortex (low Fr, low Re), out‐of‐phase counter‐rotating toroidal vortex (high Fr, low Re). Turbulence levels are found to be significant only in the top right quadrant (high Fr, low Re) and scaling of the turbulent kinetic energy obtained with fluid of varying viscosity is obtained by employing the ratio of the operating Froude number to the critical Froude number associated to the mean flow transition, Fr/Frc. Estimates of the mean flow strain deformation as well as of the flow dissipative scale are provided, while a comparison is made between the flow circulation times obtained for different regimes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-09-01T07:25:40.810259-05:
      DOI: 10.1002/aic.14608
       
  • Enhanced performance of supercritical fluid foaming of natural‐based
           polymers by deep eutectic solvents
    • Authors: Marta Martins; Ivo Aroso, Rita Craveiro, Rui L. Reis, Alexandre Paiva, Ana Rita C. Duarte
      Pages: n/a - n/a
      Abstract: Natural deep eutectic solvents are defined as a mixture of two or more solid or liquid components, which at a particular composition present a high melting point depression becoming liquids at room temperature. NADES are constituted by natural molecules and fully represent the green chemistry principles. For these reasons the authors believe that the submitted manuscript is a highly valuable contribution to the field of green chemistry and chemical engineering. In this work we reveal for the first time the possibility to use NADES as enhancers of supercritical fluid technology. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-30T03:34:16.650527-05:
      DOI: 10.1002/aic.14607
       
  • UNIFAC model for ionic liquid‐CO (H2) systems: An experimental and
           modeling study on gas solubility
    • Authors: Zhigang Lei; Chengna Dai, Qian Yang, Jiqin Zhu, Biaohua Chen
      Pages: n/a - n/a
      Abstract: The UNIFAC model for ionic liquids (ILs) has become notably popular because of its simplicity and availability via modern process simulation softwares. In this work, new group binary interaction parameters (αmn and αnm) between CO (H2) and IL groups were obtained by correlating the solubility data in pure ILs at high temperatures (above 273.2 K) collected from the literature. We also measured the solubility of CO in [BMIM]+[BF4]‐, [OMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, as well as that of H2 in [EMIM]+[BF4]‐, [BMIM]+[BF4]‐, [OMIM]+[Tf2N]‐ and their mixtures, at temperatures from 243.2 to 333.2 K and pressures up to 6.0 MPa. The UNIFAC model was observed to well predict the solubility in pure and mixed ILs at both high (above 273.2 K) and low (below 273.2 K) temperatures. Moreover, the selectivity of CO (or H2) to CO2 in ILs increases with decreasing temperature, indicating that low temperatures favor for gas separation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-28T02:12:45.692518-05:
      DOI: 10.1002/aic.14606
       
  • Magnetic nanowire synthesis: A Chemical Engineering approach
    • Authors: Ouar Nassima; Farhat Samir, Hinkov Ivaylo, Wang Guillaume, Ricolleau Christian, Mercone Silvana, Zighem Fatih, Schoenstein Frédéric, Jouini Noureddine
      Pages: n/a - n/a
      Abstract: Bimetallic one‐dimensional (1‐D) cobalt‐nickel magnetic nanowires capped on both sides with conical heads were synthesized using the polyol process. Then, the process was scaled up to produce magnetic nanowires in sample aliquots of ˜20 grams. The scale‐up strategy involved improving the mixing reagents using either axial or radial mixing configurations and was experimentally validated by comparing the structural and magnetic properties of the resulting nanowires. The results indicated a connection between the flow patterns and the size and shape of the nanowires. When a Rushton turbine was used, shorter nanowires with unconventional small heads were obtained. Because the demagnetizing field is strongly localized near or inside these heads, the coercive field was enhanced nearly twofold. These results were confirmed by micromagnetic simulations using isolated nanowires. In addition, the development of flow patterns at the small and pilot scales was predicted and compared using three‐dimensional (3‐D) turbulent computational fluid dynamics simulations. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-28T02:06:40.893947-05:
      DOI: 10.1002/aic.14605
       
  • Modeling of turbulent cross flow microfiltration of pomegranate juice
           using hollow fiber membranes
    • Authors: Sourav Mondal; Sirshendu De, Alfredo Cassano, Franco Tasselli
      Pages: n/a - n/a
      Abstract: A mathematical analysis of the permeate flux decline during microfiltration of fruit juice with hollow fibers under turbulent flow is presented. Impact of complex fluid flow phenomena on mass transfer is analyzed. A comprehensive analytical model for developing concentration boundary layer was formulated from first principles using integral method. Attempts to model the system considering constant boundary layer thickness (film theory) is inaccurate for developing boundary layer. Gel resistance parameter depending on juice characteristics has significant impact on permeate flux. Specific gel layer concentration has insignificant effect on system performance under total recycle mode but important for batch mode. Theoretical results were compared with experiments in clarification of pomegranate juice with poly(ether ether ketone) and polysulfone hollow fiber membranes. The physical parameters of complex mixture were evaluated by optimizing of the flux profiles in total recycle mode of operation and were successfully applied for prediction of batch mode performance. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T14:31:54.531115-05:
      DOI: 10.1002/aic.14594
       
  • An integrated qualitative and quantitative modeling framework for
           computer‐assisted HAZOP studies
    • Authors: Jing Wu; Laibin Zhang, Jinqiu Hu, Morten Lind, Xinxin Zhang, Sten Bay Jørgensen, Gürkan Sin, Niels Jensen
      Pages: n/a - n/a
      Abstract: The article proposes a novel practical framework for computer‐assisted hazard and operability (HAZOP) that integrates qualitative reasoning about system function with quantitative dynamic simulation in order to facilitate detailed specific HAZOP analysis. The practical framework is demonstrated and validated on a case study concerning a three‐phase separation process. The multilevel flow modeling (MFM) methodology is used to represent the plant goals and functions. First, means‐end analysis is used to identify and formulate the intention of the process design in terms of components, functions, objectives, and goals on different abstraction levels. Based on this abstraction, qualitative functional models are constructed for the process. Next MFM‐specified causal rules are extended with systems specific features to enable proper reasoning. Finally, systematic HAZOP analysis is performed to identify safety critical operations, its causes and consequences. The outcome is a qualitative hazard analysis of selected process deviations from normal operations and their consequences as input to a traditional HAZOP table. The list of unacceptable high risk deviations identified by the qualitative HAZOP analysis is used as input for rigorous analysis and evaluation by the quantitative analysis part of the framework. To this end, dynamic first‐principles modeling is used to simulate the system behavior and thereby complement the results of the qualitative analysis part. The practical framework for computer‐assisted HAZOP studies introduced in this article allows the HAZOP team to devote more attention to high consequence hazards. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T14:17:12.861552-05:
      DOI: 10.1002/aic.14593
       
  • Numerical simulation of rapid expansion of supercritical carbon dioxide
    • Authors: Jiewei Liu; Minh Do‐Quang, Gustav Amberg
      Pages: n/a - n/a
      Abstract: This paper investigates axisymmetric rapid expansion of supercritical carbon dioxide. The extended generalized Bender equation of state is used to give a good description of the fluids over a wide range of pressure and temperature conditions. The location of Mach disks are analyzed and compared with an experimental correlation for the case where there is no plate positioned in front of the nozzle exit. It is found that the disagreement between our numerical results and the experimental formula is very small when the pressure ratio is small, and increases as the pressure ratio increases. It is also found that with different equations of state, the predicted positions of Mach disks do not differ a lot, but the temperature profiles in the chamber differ a lot. This paper has also studied the case where there is a plate positioned in front of the nozzle exit. A universal similarity solution is obtained. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T10:58:59.874008-05:
      DOI: 10.1002/aic.14603
       
  • A novel fluorinated polymeric product for photo‐reversibly
           switchable hydrophobic surface
    • Authors: Yin‐Ning Zhou; Jin‐Jin Li, Qing Zhang, Zheng‐Hong Luo
      Pages: n/a - n/a
      Abstract: In this work, a new chemical product, i.e. photo‐reversibly switchable hydrophobic surface coating, was synthesized by atom transfer radical polymerization (ATRP) and graft‐from method based on molecular design. Focusing on the strategy of new product development from the chemical product engineering perspective, the product characterization, switching mechanism analysis, performance evaluation and model interpretation were carried out to confirm the new product manufacture and to ensure the product application with a following aging test. The results show that the product enables surfaces to have reversibly switchable wettability and excellent stability after a month‐long test with eight irradiation cycles. Additionally, the wetting behavior of silicon surface can be tuned between hydrophilicity and hydrophobicity based on blank sample using the surface engineering technique (decorated with functional film and surface roughening). The product presented here can be utilized for constructing a hydrophobic surface with photo‐induced controllable wettability in moisture‐resistance, and it also offers a new technique for the manipulation of liquids in microfluidic devices. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T09:37:47.887919-05:
      DOI: 10.1002/aic.14602
       
  • Cake properties of nano‐colloid evaluated by variable pressure
           filtration associated with reduction in cake surface area
    • Authors: Eiji Iritani; Nobuyuki Katagiri, Ryota Nakajima, Kuo‐Jen Hwang, Tung‐Wen Cheng
      Pages: n/a - n/a
      Abstract: A potential method has been developed for evaluating simultaneously both the average specific resistance and average porosity of the filter cake formed in unstirred dead‐end ultrafiltration of nano‐colloids such as BSA solution and silica sol. The method consists of variable pressure filtration followed by constant pressure filtration. The relation between the average specific cake resistance and the pressure drop across the cake was determined from the evolution of the filtration rate with time in the course of the variable pressure filtration period, based on the compressible cake filtration model. The average porosity was evaluated from the significant flux decline caused by a sudden reduction in the cake surface area in the middle of the constant pressure filtration period. The pressure dependences of both the average specific cake resistance and average cake porosity were obtained from only two runs which differed from each other in the pressure profiles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T09:36:26.606692-05:
      DOI: 10.1002/aic.14601
       
  • Hybrid FSC Membrane for CO2 Removal from Natural Gas: Experimental,
           Process Simulation and Economic Feasibility Analysis
    • Authors: Xuezhong He; Taek‐Joong Kim, May‐Britt Hägg
      Pages: n/a - n/a
      Abstract: The novel fixed‐site‐carrier (FSC) membranes were prepared by coating carbon nanotubes (CNTs) reinforced polyvinylamine (PVAm)/polyvinylalcohol (PVA) selective layer on top of ultrafiltration polysulfone support. Small pilot‐scale modules with membrane area of 110‐330cm2 were tested with high pressure permeation rig. The prepared hybrid FSC membranes show high CO2 permeance of 0.084~0.218 m3 (STP) / (m2.h.bar) with CO2/ CH4 selectivity of 17.9‐34.7 at different feed pressures up to 40 bar for a 10% CO2 feed gas. Operating parameters of feed pressure, flow rate and CO2 concentration were found to significantly influence membrane performance. HYSYS simulation integrated with ChemBrane and cost estimation was conducted to evaluate techno‐economic feasibility of a membrane process for natural gas sweetening. Simulation results indicated that the developed FSC membranes could be a promising candidate for CO2 removal from low CO2 concentration (10%) natural gases with a low natural gas sweetening cost of 5.73E‐3 $ / Nm3 sweet NG produced. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T02:01:53.588201-05:
      DOI: 10.1002/aic.14600
       
  • CFD Modeling of LPG Vessels under Fire Exposure Conditions
    • Authors: Arianna D’aulisa; Gabriele Landucci, Alessandro Tugnoli, Valerio Cozzani, Albrecht Michael Birk
      Pages: n/a - n/a
      Abstract: Fire exposure of tanks used for the storage and transportation of liquefied gases under pressure may cause complex heat and mass transfer phenomena that may contribute to compromise the integrity of the vessels in accident scenarios. Heat transfer through vessel lading results in the heat‐up of the internal fluid and the increase of vessel internal pressure. However, local temperature gradients in the liquid phase cause liquid stratification phenomena that result in a more rapid vaporization and pressure build‐up in the liquid phase. These fundamental phenomena were analyzed by a Computational Fluid Dynamic (CFD) model. The model was specifically focused on the early steps of vessel heat‐up, when liquid stratification plays a relevant role in determining the vessel internal pressure. A two‐dimensional transient simulation was set up using ANSYS FLUENT in order to predict the evolution of the liquid and vapor phases during the tank heat up. The model was validated against available large scale experimental data available for liquefied petroleum gas (LPG) vessels exposed to hydrocarbon fires, and was applied to case studies derived from recent accidental events in order to assess the expected time of pressure build‐up in different fire scenarios. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-27T01:54:41.674435-05:
      DOI: 10.1002/aic.14599
       
  • Boundary conditions for collisional granular flows of frictional and
           rotational particles at flat walls
    • Authors: Yunhua Zhao; Yingjie Zhong, Yurong He, H. Inaki Schlaberg
      Pages: n/a - n/a
      Abstract: Collisions between frictional particles and flat walls are determined using Coulomb friction and both tangential and normal restitution, and pseudothermal states of particles are described by both the translational and rotational granular temperatures. Then, new models for the stresses and the fluxes of fluctuation energy for the collisional granular flows at the walls are derived. These new models are tested and compared with the literature data and models. The ratio of rotational to translational granular temperatures is shown to be crucial on accurately predicting the shear stress and energy flux and is dependent on the normalized slip velocity as well as the collisional parameters. Using a theoretical but constant value for this ratio, predictions by the new models could still agree better with the literature data than those by the previous models. Finally, boundary conditions are developed to be used within the framework of kinetic theory of granular flow. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-25T21:08:42.042732-05:
      DOI: 10.1002/aic.14596
       
  • Measurement of particle concentration in a Wurster fluidized bed by
           electrical capacitance tomography sensors
    • Authors: Ruihuan Ge; Jiamin Ye, Haigang Wang, Wuqiang Yang
      Pages: n/a - n/a
      Abstract: It is essential to measure and monitor the particle flow characteristics in a Wurster fluidized bed to understand and optimize the coating processes. In this article, two electrical capacitance tomography (ECT) sensors are used to measure the particle concentration in different regions in a Wurster fluidized bed for the “cold” particle flows. One ECT sensor has a 12‐4 internal‐external electrodes and another has eight electrodes. The 12‐4‐electrode ECT sensor is used to measure the particle concentration in the annular fluidization region (outside of the Wurster tube) and the eight‐electrode ECT sensor is used to measure the particle flow in the central region (inside the Wurster tube). The effect of particle type, particle moisture, fluidization velocity, and geometrical parameters on the Wurster fluidization process is studied based on the two ECT measurements. The radial particle concentration profiles in the annular fluidization and central flow regions with different operation parameters are given. Fast Fourier Transform analysis of the particle concentration in the Wurster tube is performed with different superficial air velocities. The optimum operating ranges of the Wurster fluidization process for different particles are given. In the end of the article, computational fluids dynamics simulation results are given and used to compare with the measurement results by ECT for a typical Wurster fluidized bed. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-25T20:59:06.104639-05:
      DOI: 10.1002/aic.14595
       
  • Minimum entropy generation for isothermal endothermic/exothermic reactor
           networks
    • Authors: Paul G. Ghougassian; Vasilios Manousiouthakis
      Pages: n/a - n/a
      Abstract: In our earlier work, it was shown that entropy generation and energy (hot utility or cold utility) consumption of isothermal, isobaric reactor networks depend only on the network’s inlet and outlet stream compositions and flow rates and are not dependent on the reactor network structure, as long as the universe of realizable reactor units and network outlet mixing units are either all endothermic interacting with a single hot reservoir, or all exothermic interacting with a single cold reservoir respectively. In this work, it is shown that when the universe of realizable reactor/mixer units, of isothermal, isobaric, continuous stirred tank reactor networks, consists of both endothermic units interacting with a single hot reservoir and exothermic units interacting with a single cold reservoir, the network’s net (hot minus cold) utility consumption depends only on the network’s inlet and outlet stream compositions and flow rates (and does not depend on the network’s structure). In contrast, the network’s entropy generation depends on the network’s inlet and outlet stream compositions and flow rates, and the network’s hot utility (or cold utility) consumption. The latter, in general, depends on the network structure, thus making entropy generation also, in general, depend on network structure. Thus the synthesis of isothermal, isobaric reactor networks, with fixed inlet and outlet stream specifications, is equivalent to the synthesis of minimum hot (or cold) utility consuming such networks. The Infinite DimEnsionAl State‐space (IDEAS) conceptual framework is employed for the problem’s mathematical formulation, which is then used to rigorously establish the above equivalence. A case study involving Trambouze kinetics demonstrates the findings. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-21T10:56:53.104694-05:
      DOI: 10.1002/aic.14598
       
  • A mechanistic growth model for inorganic crystals: Solid‐state
           interactions
    • Authors: Preshit Dandekar; Michael F. Doherty
      Pages: n/a - n/a
      Abstract: Growth shapes of inorganic crystalline solids govern material properties such as catalytic activity and selectivity, solar cell efficiency, etc. A systematic understanding of the crystal growth process and the solid‐state interactions within inorganic crystals should help to engineer crystal shapes. We present a general model that identifies periodic bond chains in inorganic crystals while accounting for the long‐range electrostatic interactions. The variation in the electronic structure and the partial charges of growth units on the inorganic crystal surfaces has been captured using the bond valence model. The electrostatic interaction energies in the kink sites of inorganic crystals were calculated using a space partitioning method that is computationally efficient. This model provides a quantitative explanation for the asymmetric growth spirals formed on the surface of calcite. This methodology studying solid‐state interactions can be used with a mechanistic growth model to predict the morphology of a wide variety of inorganic crystals. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-21T02:29:25.776293-05:
      DOI: 10.1002/aic.14597
       
  • Global optimality properties of total annualized and operating cost
           problems for compressor sequences
    • Authors: Jeremy A. Conner; Vasilios I. Manousiouthakis
      Pages: n/a - n/a
      Abstract: In this work, the minimum total annualized cost problem is studied for a series of non‐isentropic compressors and coolers that brings a gas with constant compressibility factor from a specified initial pressure and temperature to a specified final pressure and the same temperature. It is established analytically that at the global optimum, the cooler outlet temperatures are equal to the minimum allowable temperature. For constant heat capacity, constant compressibility factor gases, additional properties of the globally optimal compressor sequence are analytically established for the minimum operating cost case. The aforementioned properties permit development of a solution strategy that identifies the globally‐minimum operating cost. Several case studies are presented to illustrate the developed theorems and solution strategies. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T09:40:36.178594-05:
      DOI: 10.1002/aic.14580
       
  • Distributed Lyapunov‐based model predictive control with
           neighbor‐to‐neighbor communication
    • Authors: Su Liu; Jinfeng Liu
      Pages: n/a - n/a
      Abstract: We consider distributed predictive control of large‐scale nonlinear systems with neighbor‐to‐neighbor communication. This work fulfills the gap between the existing centralized Lyapunov‐based MPC (LMPC) and the cooperative distributed LMPC and provides a balanced solution in terms of implementation complexity and achievable performance. We focus on a class of nonlinear systems with subsystems interacting with each other via their states. For each subsystem, an LMPC is designed based on the subsystem model and the LMPC only communicates with its neighbors. At a sampling time, a subsystem LMPC optimizes its future control input trajectory assuming that the states of its upstream neighbors remain the same as (or close to) their predicted state trajectories obtained at the previous sampling time. Both non‐iterative and iterative implementation algorithms are considered. The performance of the proposed designs are illustrated via a chemical process example. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T06:12:03.418863-05:
      DOI: 10.1002/aic.14579
       
  • Modified gas‐translation model for prediction of gas permeation
           through microporous organosilica membranes
    • Authors: Hiroki Nagasawa; Takuya Niimi, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
      Pages: n/a - n/a
      Abstract: A modified gas‐translation (GT) model was applied for the theoretical analysis of gas permeation through microporous organosilica membranes derived from bis(triethoxysilyl)ethane (BTESE) via a sol‐gel method using different water/alkoxide molar ratios. The pore sizes of BTESE‐derived membranes were quantitatively determined by Normalized Knudsen‐based Permeance (NKP) analysis, which was based on a modified‐GT model, using experimentally obtained permeances of He, H2, N2, C3H8, and SF6. The pore sizes of BTESE‐derived membranes were successfully controlled from 0.65 to 0.46 nm by increasing the H2O/BTESE ratio from 6 to 240. Furthermore, theoretical correlations of all possible pairs of permeance ratios were calculated based on the modified‐GT model. The experimental data were in good agreement with the theoretical correlation curves, indicating that the modified‐GT model can clearly explain gas permeation mechanisms through microporous membranes, and, thus, can be used to predict the gas permeation properties for these membranes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T06:06:22.375282-05:
      DOI: 10.1002/aic.14578
       
  • Mechanism and kinetic modeling for steam reforming of toluene on
           La0.8Sr0.2Ni0.8Fe0.2O3 catalyst
    • Authors: Usman Oemar; Ang Ming Li, Kus Hidajat, Sibudjing Kawi
      Pages: n/a - n/a
      Abstract: Reaction mechanism for steam reforming of toluene is proposed for La0.8Sr0.2Ni0.8Fe0.2O3 (LSNFO) perovskite catalyst. The proposed mechanism was derived from various characterization results such as TPD and TPSR water, TPSR toluene, TPD O2 and in‐situ DRIFT of toluene decomposition and steam reforming of toluene. Five kinetic models were developed based on the proposed dual‐site reaction mechanism using Langmuir‐Hinshelwood (LH) approach. Subsequently, the parameters of the kinetic models were estimated by non‐linear least square regression. A good agreement was obtained between experimental and model predicted results for the rate determining step (RDS) based on reaction between adsorbed aldehyde and adsorbed oxygen. The adsorbed aldehyde species is produced from the reaction between adsorbed C2H2 or CH2 and adsorbed oxygen while the adsorbed oxygen species can come from the oxygen from water activation, lattice oxygen species, and/or the redox property of some metals such as Fe. This shows that the adsorbed oxygen species plays important role in this reaction. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-11T05:36:59.473292-05:
      DOI: 10.1002/aic.14573
       
  • A numerical study of dynamic capillary pressure effect for supercritical
           carbon dioxide‐water flow in porous domain
    • Authors: Diganta B. Das; Bhupinder S. Gill, Luqman K. Abidoye, Kamal Khudaida
      Pages: n/a - n/a
      Abstract: Numerical simulations for core‐scale capillary pressure (Pc)–saturation (S) relationships have been conducted for a supercritical carbon dioxide‐water system at temperatures between 35°C and 65°C at a domain pressure of 15 MPa as typically expected during geological sequestration of CO2. As the Pc‐S relationships depend on both S and time derivative of saturation (∂S / ∂t) yielding what is known as the ‘dynamic capillary pressure effect’ or simply ‘dynamic effect’, this work specifically attempts to determine the significance of these effects for supercritical carbon dioxide‐water flow in terms of a coefficient, namely dynamic coefficient (τ). The coefficient establishes the speed at which capillary equilibrium for supercritical CO2‐water flow is reached. The simulations in this work involved the solution of the extended version of Darcy’s law which represents the momentum balance for individual fluid phases in the system, the continuity equation for fluid mass balance, as well as additional correlations for determining the capillary pressure as a function of saturation, and the physical properties of the fluids as a function of temperature. The simulations were carried for 3D cylindrical porous domains measuring 10 cm in diameter and 12 cm in height. τ was determined by measuring the slope of a best‐fit straight line plotted between (i) the differences in dynamic and equilibrium capillary pressures (Pc,dyn – Pc,equ) against (ii) the time derivative of saturation (dS/dt), both at the same saturation value. The results show rising trends for τ as the saturation values reduce, with noticeable impacts of temperature at 50% saturation of aqueous phase. This means that the time to attain capillary equilibrium for the CO2‐water system increases as the saturation decreases. From a practical point view, it implies that the time to capillary equilibrium during geological sequestration of CO2 is an important factor and should be accounted for while simulating the flow processes, e.g., to determine the CO2 storage capacity of a geological aquifer. In this task, one would require both the fundamental understanding of the dynamic capillary pressure effects for supercritical CO2‐water flow as well as τ values. These issues are addressed in this article. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-08T11:58:12.148498-05:
      DOI: 10.1002/aic.14577
       
  • Near‐wall convection in a sedimenting suspension of fibres
    • Authors: Feng Zhang; Katarina Gustavsson, Fredrik Lundell, Anders A. Dahlkild
      Pages: n/a - n/a
      Abstract: The sedimentation of a fibre suspension near a vertical wall is investigated numerically. Initially, the near‐wall convection is an upward backflow, which originates from the combined effects of the steric‐depleted layer and a hydrodynamically‐depleted region near the wall. The formation of the hydrodynamically‐depleted region is elucidated by a convection‐diffusion investigation, in which fibres are classified according to the different directions in which they drift. For fibres with sufficiently large aspect ratio, the initial near‐wall backflow keeps growing. However, the backflow reverses to downward flow at later times if the aspect ratio is small. This is due to the fibre‐wall interactions which rotate fibres to such angles that make fibres drift away from the wall, inducing a dense region and a correspondingly downward flow outside the initial backflow. Moreover, the steric‐depleted boundary condition is of secondary importance in the generation and evolution of the near‐wall convection. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-08T11:35:18.80853-05:0
      DOI: 10.1002/aic.14576
       
  • Analysis of plug flow reactors with variable mass density
    • Authors: J. S. Vrentas; C. M. Vrentas
      Pages: n/a - n/a
      Abstract: The design of plug flow reactors with variable mass density is examined. Equations which include a two‐term constitutive equation for the reaction rate are derived for the flow of liquids and for the flow of ideal gases in steady plug flow reactors. It is shown that the addition of the second term in the constitutive equation can have a significant effect on the calculation of the reactor volume needed to carry out a specific conversion of the reactant. Published experimental plug flow reactor data support the observation that a reaction rate constitutive equation with two terms can provide a good representation of the experimental data for variable mass density reactors. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-06T07:35:05.487258-05:
      DOI: 10.1002/aic.14574
       
  • Influence of loading rate and pre‐loading on the mechanical
           properties of dry elasto‐plastic granules under compression
    • Authors: Alexander Russell; Peter Müller, Hao Shi, Jürgen Tomas
      Pages: n/a - n/a
      Abstract: In order to ensure high quality of granular products post‐industrial operations, it is necessary to precisely define their micro‐macro mechanical properties. However, such an endeavor is arduous, owing to their highly inhomogeneous, anisotropic and history‐dependent nature. In this article, we present the distributed granular micro‐ and macro‐mechanical, energetic and breakage characteristics using statistical distributions. We describe the material behavior of elasto‐plastic zeolite 4AK granules under uniaxial compressive loading until primary breakage, and localized cyclic loading up to different maximum force levels, at different displacement‐controlled loading rates. The observed force‐displacement behavior had been approximated and further evaluated using well‐known contact models. The results provide the basis for a detailed analysis of the viscous behavior of zeolite 4AK granules in the moist and wet states, indicating that higher compressive loads are required at higher displacement‐controlled loading rates to realize equivalent deformation and breakage probability achieved by loads at lower displacement‐controlled loading rates. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-04T06:00:36.692376-05:
      DOI: 10.1002/aic.14572
       
  • Continuous flow characterization of solid biomass in a
           reciprocating/rotating scraper tube: An experimental study
    • Authors: Kamelia V.K. Boodhoo; Lily Smith, Juan Pedro Solano, Mark Gronnow, James Clark
      Pages: n/a - n/a
      Abstract: The performance of reciprocating/rotating scrapers has been assessed in a visualization study of the continuous flow hydrodynamics of air‐fluidized solid biomass under varying conditions of air flow rate and scraping velocities. A combination of low air flow rates and high scraping velocities result in more uniform flow of both types of biomass investigated. Power consumed by the reciprocating action of the scrapers increases with the scraping velocity but typically represents no more than 20% of the overall power consumption at the highest air flow rate applied. We also demonstrate that rotation of the scrapers superimposed on their reciprocating action gives higher flow rate of biomass and better mixing within the bulk solid compared to reciprocating action alone. The application of the reciprocating/rotating scraper technology described in this study represents a viable step forward in developing a continuous, large‐scale process for the microwave‐assisted decomposition of solid biomass to produce bio‐oils. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-04T05:20:37.661511-05:
      DOI: 10.1002/aic.14571
       
  • Analytical models of penetration depth during slot die coating onto porous
           media
    • Authors: Xiaoyu Ding; Zhuo Li, Joshua Prince Ebin, Thomas F. Fuller, Tequila A.L. Harris
      Pages: n/a - n/a
      Abstract: A series of analytical models have been developed to predict the penetration depth during slot die coating on porous media. Analytical models for both Newtonian and non‐Newtonian fluids were derived based on Lubrication Theory, Darcy’s law, and a modified Blake‐Kozeny equation. Using these models, the penetration depth can be quickly solved and the effects of material properties and processing conditions on penetration depth can be easily investigated. Experiments of coating Newtonian glycerin and non‐Newtonian blackstrap molasses onto Toray series carbon paper were conducted to validate developed models. The overall relative error between the predicted and measured penetration depth was found to be typically lower than 20%, which demonstrates the relative accuracy of developed models. Furthermore, based on a parametric study, it was found that the effect of capillary pressure on penetration depth is less than 10% when the ratio of coating bead pressure and capillary pressure is larger than 10. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-01T10:49:24.54136-05:0
      DOI: 10.1002/aic.14570
       
  • Experimental investigation of continuous single‐phase rimming flow
           in a horizontal rotating cylinder
    • Authors: Saravanan Suppiah Singaram; Roshan J Jachuck, Himanshu Lodha
      Pages: n/a - n/a
      Abstract: Rimming flow of water that leads to a thin film onto the inner surface of a horizontally rotating cylinder is studied in this work. At higher rotational speeds, axial flow of uniform thin film is established inside the rotating cylinder. Film thickness measurements under different flow conditions were performed in the annular flow regime using an optical interferometric technique. Dimensional analysis was also performed to understand the parametric dependence of key parameters involved in the rimming flow of water inside a horizontal rotating cylinder and expressions to determine average film thickness and average residence time are also presented. This current study will provide a basis to estimate the transport characteristics in the thin film inside the horizontal rotating cylinder. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-08-01T05:36:07.46609-05:0
      DOI: 10.1002/aic.14569
       
  • Formation of defect-free polyetherimide/PIM-1 hollow fiber membranes for
           gas separation
    • Authors: Lin Hao; Jian Zuo, Tai-Shung Chung
      Pages: n/a - n/a
      Abstract: Dual-layer hollow fiber membranes were produced from blends of Ultem and polymer of intrinsic microporosity (PIM-1) with enhanced gas permeance. The effects of spinning parameters (take-up speed and air gap distance) on gas separation performance were investigated based on the pristine Ultem. Selected spinning conditions were further adopted for the blend system, achieving defect-free and almost defect-free hollow fibers. Adding PIM results in a higher fractional free volume, 50% increments in gas permeance were observed for Ultem/PIM-1 (95/5) and more than 100% increments for Ultem/PIM-1 (85/15). Both O2/N2 and CO2/CH4 selectivities remained the same for Ultem/PIM-1 (95/5) and above 80% of their respective intrinsic values for Ultem/PIM-1 (85/15). The selective layer thickness ranges from 70 to 120 nm, indicating the successful formation of ultrathin dense layers. Moreover, minimum amounts of the expensive material were consumed, that is, 0.88, 1.7, and 2.3 wt % PIM-1 for Ultem/PIM-1 (95/5), (90/10), and (85/15), respectively. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-28T14:09:07.6357-05:00
      DOI: 10.1002/aic.14565
       
  • Model reduction for linear simulated moving bed chromatography systems
           using Krylov-subspace methods
    • Authors: Suzhou Li; Yao Yue, Lihong Feng, Peter Benner, Andreas Seidel-Morgenstern
      Pages: n/a - n/a
      Abstract: Simulated moving bed (SMB) chromatography is a well-established technology for separating chemical compounds. To describe an SMB process, a finite-dimensional multistage model arising from the discretization of partial differential equations is typically employed. However, its relatively high dimension poses severe computational challenges to various model-based analysis. To overcome this challenge, two Krylov-type model order reduction (MOR) methods are proposed to accelerate the computation of the cyclic steady states (CSSs) of SMB processes with linear isotherms. A “straightforward method” that carefully deals with the switching behavior in MOR is first proposed. Its improvement, a “subspace-exploiting method,” thoroughly exploits each reduced model to achieve further acceleration. Simulation studies show that both methods achieve high accuracy and significant speedups. The subspace-exploiting method turns out to be computationally much more efficient. Two challenging analyses of SMB processes, namely uncertainty quantification and CSS optimization, further demonstrate the accuracy, efficiency, and applicability of the proposed methods. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-28T14:03:09.521068-05:
      DOI: 10.1002/aic.14561
       
  • Experimental validation of a flexible modeling approach for distillation
           columns with packings
    • Authors: Christoph Ehlers; Georg Fieg
      Pages: n/a - n/a
      Abstract: The two main concepts for the modeling of distillation columns are the equilibrium-stage (EQ) and the nonequilibrium-stage (NEQ). A model is presented which combines decisive features of both conventional concepts. Based on the idea of a reduced nonequilibrium-stage (RNEQ), this model can be used for the simulation of distillation columns with packings. In contrast to the conventional NEQ approach, this model neglects the influence of liquid side mass-transfer coefficients, which ultimately allows to come up with only one empirical equation describing the overall mass transfer. Thus, a considerable reduction in model complexity is reached, which allows for an efficient consideration of new experimental distillation results. Fitted to experimental data, the model is able to predict, how different pressures and chemical systems might affect the separation efficiency. By comparing calculation results with experimentally determined separation efficiencies for three different packing types, these valuable RNEQ qualities are illustrated. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T13:22:23.478698-05:
      DOI: 10.1002/aic.14560
       
  • Mixing potential: A new concept for optimal design of hydrogen and water
           networks with higher disturbance resistance
    • Authors: Zuwei liao; Junyi Lou, Jingdai Wang, Binbo Jiang, Yongrong Yang
      Pages: n/a - n/a
      Abstract: During the last decade, the design methods of hydrogen and water networks have been improved greatly. Since the resulting network structure featuring minimum utility consumption is not unique, other properties such as disturbance resistance have drawn more and more attention. In this article, a novel concept, Mixing Potential, is proposed to improve the disturbance resistance ability of the networks in the design stage. This concept originates from measuring the concentration fluctuation of a single sink, and could be calculated by its graphical and algorithmic definition, respectively. In addition, a sufficient condition for minimizing the Mixing Potential of a single sink has been proved. Based on this sufficient condition, a graphical and its corresponding algorithmic method are proposed to design the hydrogen and water networks with minimum utility consumption. Literature examples illustrate that the disturbance resistance ability of the network can be improved by adjusting the satisfying order of sinks. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T13:22:01.598619-05:
      DOI: 10.1002/aic.14556
       
  • Impact of separator’s solid phase ion conductivity parameter on
           convection battery performance and modeling
    • Authors: R. Hilton; M. Gordon, D. Dornbusch, G. J. Suppes
      Pages: n/a - n/a
      Abstract: A solid phase ion conductivity parameter has been added to the separator of a porous electrode theory description of a convection battery performance to increase the accuracy of this model. With the addition of the ion conductivity parameter, the variances between the model and experimental data have been reduced by 80-85% in both the convection cell and the diffusion cell. The parameter is fundamentally consistent with solid phase mechanisms by which ions can transport through separators in parallel with liquid phase transport, and the improved modeling results substantiate the importance of solid or surface ion transport mechanisms at high current fluxes. Modeling was supplemented with dimensionless analysis to lump fundamental parameters that are inherently coupled in the underlying equations. From this analysis, a global parameter has been developed describing the ratio of convective charge transfer to diffusive charge transfer that characterizes the transition from diffusive to convective cell behavior. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T01:02:05.521355-05:
      DOI: 10.1002/aic.14568
       
  • Equation-oriented flowsheet simulation and optimization using
           pseudo-transient models
    • Authors: Richard C. Pattison; Michael Baldea
      Pages: n/a - n/a
      Abstract: Tight integration through material and energy recycling is essential to the energy efficiency and economic viability of process and energy systems. Equation-oriented steady state process simulation and optimization are key enablers in the optimal design of integrated processes. In this paper a new process modeling and simulation concept based on pseudo-transient continuation is introduced. We present an algorithm for reformulating the steady-state models of process unit operations as differential-algebraic equation (DAE) systems that are statically equivalent with the original model. We show that these pseudo-transient models improve the convergence of equation-oriented process flowsheet simulations by expanding the convergence basin. We use this concept to build a library of pseudo-transient models for common process unit operations, and show that this modeling concept seamlessly integrates with a previously developed time-relaxation optimization algorithm. Two design case studies are presented to validate the proposed framework. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-24T00:28:29.260326-05:
      DOI: 10.1002/aic.14567
       
  • Phase Equilibria and Structural Properties of Thiophene/[Bmim][BF4]: A
           Molecular Insight from Monte Carlo Simulations
    • Authors: Yongping Zeng; Chunfeng Wang, Yueyang Xu, Junmei Hu, WenLin Xu, Shengui Ju
      Pages: n/a - n/a
      Abstract: The phase equilibria of thiophene in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim][BF4]) is calculated by Monte Carlo simulation in Gibbs ensemble using a united atom force field. The liquid density of studied ionic liquid and the vapor pressure of thiophene in [Bmim][BF4] were compared with corresponding experimental data reported in the literature, and a good agreement was obtained. In order to describe the solubility of thiophene in this ionic liquid, we have calculated the radial distribution functions and spatial distribution functions of thiophene/IL mixtures to study the interaction of thiophene with cations and anions of [Bmim][BF4] in the liquid phase. The local composition concept in fluid was also examined to give further insight into the liquid structure. The results show that thiophene is well organized around the terminal carbon atom of the butyl or methyl chain attached to the imidazolium ring of cations and tends to adopt a symmetrically distribution on the anions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-21T05:24:07.325795-05:
      DOI: 10.1002/aic.14566
       
  • A lattice Boltzmann simulation of mass transport through composite
           membranes
    • Authors: Li-Zhi Zhang
      Pages: n/a - n/a
      Abstract: Composite membranes with a porous support layer and a dense skin layer have been extensively used in gas separation processes. In this study, a new approach, a meso-scale Lattice Boltzmann Simulation approach (LBM), is proposed and used to model the pore-scale gas flow and mass transfer in the inhomogeneous membrane matrixes. Only physical forces are considered. Chemical forces are equivalently converted to physical forces through the relaxation time. Selective permeation of moisture through a composite membrane is modeled. The overall permeability is evaluated. It is found that mass transfer inhomogeneity exists not only in the porous media, but also in the seemingly uniform dense skin layer. Increasing the diffusivity in the skin layer is more effective than decreasing the skin layer thickness in optimizing the overall membrane performance. The new approach gives more detailed insights into the directions for future design of composite membranes for gas separations like air dehumidification. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-19T06:59:00.05676-05:0
      DOI: 10.1002/aic.14564
       
  • The adjustable synergistic effects between acid-base coupling bifunctional
           ionic liquid extractants for rare earth separation
    • Authors: Xiaoqi Sun; Kristian E Waters
      Pages: n/a - n/a
      Abstract: Two of the most widely used industrial extractants for rare earth elements (REEs), i.e., di(2-ethylhexyl)phosphoric acid (HDEHP) and 2-ethyl(hexyl) phosphonic acid mono-2-ethylhexyl ester (HEH[EHP]) were developed into [DEHP]- type acid-base coupling bifunctionalized ionic liquids (ABC-BILs) and [EHEHP]- type ABC-BILs, respectively. The combinations of ABC-BIL extractants revealed obviously synergistic effects for REEs. Seven different combinations of ABC-BILs and five kinds of REEs confirmed the novel synergistic extraction. Some synergy coefficients of the combined ABC-BILs were bigger than those of mixed HDEHP and HEH[EHP] by two orders of magnitude. This paper reports the first synergistic extraction produced by ionic liquid extractants in the field of solvent extraction. The novel synergistic extraction from combined ABC-BILs extractants revealed highly efficient and environmentally friendly potential in both of academic research and industrial application for REEs separation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-19T03:06:18.682879-05:
      DOI: 10.1002/aic.14563
       
  • Microwave assisted flow synthesis: Coupling of electromagnetic and
           hydrodynamic phenomena
    • Authors: Narendra G. Patil; Faysal Benaskar, Jan Meuldijk, Lumbertus A. Hulshof, Volker Hessel, Jaap C. Schouten, Erik D. C. Esveld, Evgeny V. Rebrov
      Pages: n/a - n/a
      Abstract: This article describes the results of a modeling study performed to understand the microwave heating process in continuous-flow reactors. It demonstrates the influence of liquid velocity profiles on temperature and microwave energy dissipation in a microwave integrated milli reactor-heat exchanger. Horizontal cocurrent flow of a strong microwave absorbing reaction mixture (ethanol + acetic acid, molar ratio 5:1) and a microwave transparent coolant (toluene) was established in a Teflon supported quartz tube (i.d.: 3 × 10−3 m and o.d.: 4 × 10−3 m) and shell (i.d.: 7 × 10−3 m and o.d.: 9 × 10−3 m), respectively. Modeling showed that the temperature rise of the highly microwave absorbing reaction mixture was up to four times higher in the almost stagnant liquid at the reactor walls than in the bulk liquid. The coolant flow was ineffective in controlling the outlet reaction mixture temperature. However, at high flow rates it limits the overheating of the stagnant liquid film of the reaction mixture at the reactor walls. It was also found that the stagnant layer around a fiber optic temperature probe, when inserted from the direction of the flow, resulted in much higher temperatures than the bulk liquid. This was not the case when the probe was inserted from the opposite direction. The experimental validations of these modeling results proved that the temperature profiles depend more on the reaction mixture velocity profiles than on the microwave energy dissipation/electric field intensity. Thus, in flow synthesis, particularly where a focused microwave field is applied over a small tubular flow reactor, it is very important to understand the large (direct/indirect) influence of reactor internals on the microwave heating process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-07-18T13:35:33.306397-05:
      DOI: 10.1002/aic.14552
       
  • A mechanistic growth model for inorganic crystals: Growth mechanism
    • Authors: Preshit Dandekar; Michael F. Doherty
      First page: 3720
      Abstract: Inorganic crystals grown from solution find wide application. We present a mechanistic growth model based on the spiral growth mechanism that operates at low supersaturation on inorganic crystal surfaces. The long-range electrostatic interactions on inorganic crystal surfaces are captured by methods developed in our previous paper1. The interactions of kink site growth units with the solvent molecules partially determine the growth kinetics. Relevant experimental parameters are systematically accounted for in the expression for the kink incorporation rate along step edges on the crystal surfaces. The growth model accurately predicts the asymmetric growth spirals on the (101¯4) surface of calcite crystals. The effect of supersaturation and ionic activity ratio on the step velocities of the acute and obtuse spiral edges is correctly captured. This model can be used to predict the shapes of solution grown inorganic crystals and to engineer the growth process to design inorganic solids with functionally desirable shapes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-05-28T08:30:09.968276-05:
      DOI: 10.1002/aic.14513
       
  • A novel hybrid feedstock to liquids and electricity process: Process
           modeling and exergoeconomic life cycle optimization
    • Authors: Chang He; Fengqi You, Xiao Feng
      Pages: 3739 - 3753
      Abstract: This article proposes a novel hybrid low‐rank coal (LRC)/biomass/natural gas process for producing liquid fuels and electricity. The hybrid process highlights coexistence of indirect and direct liquefaction technologies, cogasification of char and biomass, and corefinery of LRC syncrude and Fischer–Tropsch syncrude. A process simulation based on detailed chemical kinetics is present to illustrate its feasibility. In addition, we propose an exergoeconomic life cycle optimization framework that seeks to maximize the primary exergy saving ratio, primary total overnight cost saving ratio, life cycle waste emissions avoidance ratio, and primary levelized cost saving ratio by comparing the proposed hybrid process to its reference stand‐alone subsystems. From the results, we can determine four optimal designs which yield competitive breakeven oil prices ranging from $1.87/GGE to $2.13/GGE. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3739–3753, 2014
      PubDate: 2014-07-18T13:32:34.589941-05:
      DOI: 10.1002/aic.14551
       
  • Reconstruction of transcription factor profiles from fluorescent protein
           reporter systems via dynamic optimization and Tikhonov regularization
    • Authors: Wei Dai; Juergen Hahn, Jia Kang
      Pages: 3754 - 3761
      Abstract: This work presents a generally applicable technique for reconstructing transcription factor (TF) profiles from fluorescence microscopy images of green fluorescent protein reporter systems. The approach integrates dynamic optimization and a Tikhonov regularization to avoid over‐fitting caused by the highly ill‐conditioned structure of this inverse problem. The advantage that the presented approach has over existing methods is that no assumptions are made about the TF profile, the linearity, or lack thereof, of the dynamic model used, and the sampling time of the measurements. Moreover, the method allows to use discretization times for the model different from the measurement sampling times and can also deal with state constraints. The technique has been applied to both simulated and experimental data where the profile of the TFs NF‐κB and STAT3 are reconstructed. In both of the case studies, the presented approach exhibits excellent performance while fewer assumptions are needed than for existing techniques. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3754–3761, 2014
      PubDate: 2014-07-18T11:04:28.555781-05:
      DOI: 10.1002/aic.14559
       
  • Kinetics of CO2 absorption by aqueous 3‐(methylamino)propylamine
           solutions: Experimental results and modeling
    • Authors: Juliana G. M.‐S. Monteiro; Saddam Hussain, Hammad Majeed, Emmanuel O. Mba, Ardi Hartono, Hanna Knuutila, Hallvard F. Svendsen
      Pages: 3792 - 3803
      Abstract: Experimental data and a model for the initial kinetics of CO2 into 3‐(methylamino)propylamine (MAPA) solutions are presented in work. MAPA has been tested as an activator for tertiary amines with encouraging results. The measurements were performed in a string of discs contactor and, as no initial kinetics data are available in literature, additional measurements were carried out and in a wetted wall column. The obtained overall mass‐transfer coefficients from both apparatuses are in reasonable agreement. To obtain values for the observed kinetic constant, kobs, the experimental results were interpreted using a two‐film mass‐transfer model and invoking the pseudo‐first order assumption. Needed experimental values for density, viscosity, and Henry's law coefficient for CO2 were measured and are given. The results indicate that MAPA is almost twice as fast as piperazine, eight times faster than 2‐(2‐aminoethyl‐amino)ethanol (AEEA), and 15 times faster than monoethanolamine, when comparing unloaded 1 M solutions at 25°C. The observed kinetic constant was modeled using the direct mechanism. The final expression for kobs can be applied for any concentration and temperature within the experimental data range, and, together with the presented physical data, comprises a complete model for calculating absorption fluxes. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3792–3803, 2014
      PubDate: 2014-07-09T17:38:37.973748-05:
      DOI: 10.1002/aic.14546
       
  • Kinetic study of retro‐aldol condensation of glucose to
           glycolaldehyde with ammonium metatungstate as the catalyst
    • Authors: Junying Zhang; Baolin Hou, Aiqin Wang, ZhenLei Li, Hua Wang, Tao Zhang
      Pages: 3804 - 3813
      Abstract: The kinetics of the retro‐aldol condensation of glucose to glycolaldehyde was studied in a batch reactor at 423–453 K using ammonium metatungstate (AMT) as the catalyst. Three consecutive reactions were considered: retro‐aldol condensation of glucose to erythrose and glycolaldehyde (R1), retro‐aldol condensation of erythrose to two moles of glycolaldehyde (R2), and further conversion of glycolaldehyde to side products (R3). Fitting of the experimental data showed that R1 was first‐order reaction while R2 and R3 were 1.7th‐ and 2.5th‐order reaction, respectively. Conversely, the reaction rate of R1 was 0.257th‐order dependence on the concentration of AMT catalyst. The apparent activation energies for R1, R2, and R3 were 141.3, 79.9, and 52.7 kJ/mol, respectively. The high activation energy of R1 suggests that a high temperature is favorable to the formation of glycolaldehyde. The experimental C–t curves at different temperatures and initial glucose concentrations were well predicted by the kinetic model. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3804–3813, 2014
      PubDate: 2014-07-15T14:08:43.897286-05:
      DOI: 10.1002/aic.14554
       
  • Comparison of wash‐coated monoliths vs. microfibrous entrapped
           catalyst structures for catalytic VOC removal
    • Authors: Sabrina Wahid; Donald R. Cahela, Bruce J. Tatarchuk
      Pages: 3814 - 3823
      Abstract: Head‐to‐head experimental performance comparisons for flow through pleated microfibrous structures (flat‐, V‐, and W‐shaped) were made with wash‐coated monolith of different cells per square inch (230 and 400). Microfibrous entrapped catalyst (MFEC) was prepared by entrapping support particles (γ‐Al2O3, 150–250 μm diameter) into nickel microfibers. Pleated structures of MFECs and wash‐coated monoliths containing Pd‐Mn/γ‐Al2O3 were investigated systematically for volatile organic compound (e.g., ethanol) removal at various face velocities (ca. 3–30 m/s) and at low temperatures (≤473 K). The experimental studies showed that pleated MFEC (W‐shaped) had shown significantly improved performance in VOC removal in terms of conversion and pressure drop than tested monolith for high face velocity system. The flexibility of pleating lowered the effective velocity inside the media that resulted lower pressure drop and higher conversion. Furthermore, a reaction kinetic model was developed for pleated MFEC considering the Peffer's model to substantiate the experimental results. © 2014 American Institute of Chemical Engineers AIChE J, 60: 3814–3823, 2014
      PubDate: 2014-07-15T16:16:32.634213-05:
      DOI: 10.1002/aic.14555
       
 
 
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