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  Subjects -> ENGINEERING (Total: 1957 journals)
    - CHEMICAL ENGINEERING (150 journals)
    - CIVIL ENGINEERING (146 journals)
    - ELECTRICAL ENGINEERING (84 journals)
    - ENGINEERING (1124 journals)
    - ENGINEERING MECHANICS AND MATERIALS (284 journals)
    - HYDRAULIC ENGINEERING (43 journals)
    - INDUSTRIAL ENGINEERING (53 journals)
    - MECHANICAL ENGINEERING (73 journals)

ENGINEERING (1124 journals)            First | 1 2 3 4 5 6 7 8 | Last

Biointerphases     Open Access  
Biomaterials Science     Full-text available via subscription   (3 followers)
Biomedical Engineering     Hybrid Journal   (9 followers)
Biomedical Engineering and Computational Biology     Open Access   (12 followers)
Biomedical Engineering Letters     Hybrid Journal   (3 followers)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (14 followers)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (11 followers)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (4 followers)
Biomedical Microdevices     Hybrid Journal   (7 followers)
Biomedizinische Technik - Biomedical Engineering     Full-text available via subscription  
Biomicrofluidics     Open Access   (2 followers)
BioNanoMaterials     Full-text available via subscription   (1 follower)
Biotechnology Progress     Hybrid Journal   (21 followers)
Boletin Cientifico Tecnico INIMET     Open Access  
Boundary Value Problems     Open Access   (2 followers)
Broadcasting, IEEE Transactions on     Hybrid Journal   (5 followers)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (1 follower)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (3 followers)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (10 followers)
Canadian Journal of Remote Sensing     Full-text available via subscription   (12 followers)
Case Studies in Engineering Failure Analysis     Open Access   (3 followers)
Case Studies in Thermal Engineering     Open Access   (1 follower)
Catalysis Communications     Hybrid Journal   (3 followers)
Catalysis Letters     Hybrid Journal  
Catalysis Reviews: Science and Engineering     Hybrid Journal   (3 followers)
Catalysis Science and Technology     Free   (3 followers)
Catalysis Surveys from Asia     Hybrid Journal   (3 followers)
Catalysis Today     Hybrid Journal   (4 followers)
CEAS Space Journal     Hybrid Journal  
Cellular and Molecular Neurobiology     Hybrid Journal   (2 followers)
Central European Journal of Engineering     Hybrid Journal   (1 follower)
CFD Letters     Open Access  
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (1 follower)
Chaos, Solitons & Fractals     Hybrid Journal   (1 follower)
Chinese Journal of Catalysis     Full-text available via subscription   (1 follower)
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   (9 followers)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (10 followers)
City, Culture and Society     Hybrid Journal   (16 followers)
Clay Minerals     Full-text available via subscription   (3 followers)
Clean Air Journal     Full-text available via subscription   (2 followers)
Clinical Science     Full-text available via subscription   (4 followers)
Coal Science and Technology     Full-text available via subscription   (2 followers)
Coastal Engineering     Hybrid Journal   (6 followers)
Coastal Engineering Journal     Hybrid Journal   (2 followers)
Coatings     Open Access   (1 follower)
Cognitive Computation     Hybrid Journal   (4 followers)
Color Research & Application     Hybrid Journal   (1 follower)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (4 followers)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (8 followers)
Communications Engineer     Hybrid Journal  
Communications in Information Science and Management Engineering     Open Access   (7 followers)
Communications in Numerical Methods in Engineering     Hybrid Journal   (4 followers)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (7 followers)
Composite Interfaces     Hybrid Journal   (3 followers)
Composite Structures     Hybrid Journal   (33 followers)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (23 followers)
Composites Part B : Engineering     Hybrid Journal   (21 followers)
Composites Science and Technology     Hybrid Journal   (29 followers)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access  
Computational Geosciences     Hybrid Journal   (11 followers)
Computational Optimization and Applications     Hybrid Journal   (4 followers)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (1 follower)
Computer Applications in Engineering Education     Hybrid Journal   (6 followers)
Computer Science and Engineering     Open Access   (5 followers)
Computers & Geosciences     Hybrid Journal   (6 followers)
Computers & Mathematics with Applications     Full-text available via subscription   (4 followers)
Computers and Electronics in Agriculture     Hybrid Journal   (3 followers)
Computers and Geotechnics     Hybrid Journal   (6 followers)
Computing and Visualization in Science     Hybrid Journal   (3 followers)
Computing in Science & Engineering     Full-text available via subscription   (10 followers)
Conciencia Tecnologica     Open Access   (1 follower)
Concurrent Engineering     Hybrid Journal   (3 followers)
Continental Journal of Applied Sciences     Open Access   (3 followers)
Continental Journal of Engineering Sciences     Open Access   (1 follower)
Continuum Mechanics and Thermodynamics     Hybrid Journal   (3 followers)
Control and Dynamic Systems     Full-text available via subscription   (4 followers)
Control Engineering Practice     Hybrid Journal   (10 followers)
Control Theory and Informatics     Open Access   (3 followers)
Corrosion Science     Hybrid Journal   (18 followers)
Corrosion Series     Full-text available via subscription   (5 followers)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (4 followers)
Dams and Reservoirs     Hybrid Journal   (2 followers)
Data Handling in Science and Technology     Full-text available via subscription   (2 followers)
Design Journal     Full-text available via subscription   (12 followers)
Designed Monomers and Polymers     Hybrid Journal   (1 follower)
Designs, Codes and Cryptography     Hybrid Journal   (4 followers)
Developments in Clay Science     Full-text available via subscription  

  First | 1 2 3 4 5 6 7 8 | Last

AIChE Journal    [18 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  [1594 journals]   [SJR: 0.889]   [H-I: 94]
  • Graph reduction of complex energy‐integrated networks: Process
           systems applications
    • Authors: Seongmin Heo; Srinivas Rangarajan, Prodromos Daoutidis, Sujit S. Jogwar
      Pages: n/a - n/a
      Abstract: We illustrate the application of a graph reduction method developed recently to analyze complex energy‐integrated process networks. The method uses information on the energy flow structure of the network and the orders of magnitude of the different energy flows to generate, automatically, information on the time scales where the process units evolve, canonical forms of the reduced models in each time scale, and controlled variables and potential manipulated inputs available in each time scale. Representative examples of reactor‐heat exchanger and distillation column networks are considered to illustrate the method and develop insights on effective control strategies for these processes. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T16:00:05.873452-05:
      DOI: 10.1002/aic.14341
       
  • Kinetic study of higher alcohol synthesis directly from syngas over
           CoCu/SiO2 catalysts
    • Authors: Junjie Su; Wei Mao, Xin‐Chao Xu, Zhen Yang, Honglin Li, Jing Xu, Yi‐Fan Han
      Pages: n/a - n/a
      Abstract: Higher alcohol synthesis (HAS) directly from syngas is one of the most promising approaches for utilizing nonoil resources cleanly and efficiently. A series of bimetallic CoCu catalysts with different Co/Cu ratios were prepared using a SiO2 support. The structure of Cu modified Co catalysts was characterized using HRTEM, in/ex situ X‐ray diffraction, and temperature‐programmed reduction. It was evidenced that nanoscale metal particles were formed and the reduction of Co oxide at above 673 K. Meanwhile, the interaction between Co and Cu on the surface was assumed to be responsible for the enhanced selectivity to HAS. The intrinsic kinetics for this reaction was performed over a CoCu/SiO2 catalyst under realistic conditions. The kinetic parameters, including apparent activation energies and reaction orders, were calculated through power‐law models. With the combination of chain growth probability and kinetics, the effect of temperatures on the reaction mechanism and the Cu promotional effects on Co catalysts were elaborated. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T14:44:12.98799-05:0
      DOI: 10.1002/aic.14354
       
  • Multi‐objective optimization under uncertainty of the economic and
           life cycle environmental performance of industrial processes
    • Authors: Nagore Sabio; Carlos Pozo, Gonzalo Guillén‐Gosálbez, Laureano Jiménez, Ramkumar Karuppiah, Venkatesh Vasudevan, Nicolas Sawaya, John T. Farrell
      Pages: n/a - n/a
      Abstract: The combined use of multi‐objective optimization and LCA has recently emerged as a useful tool for minimizing the environmental impact of industrial processes. The main limitation of this approach is that it requires large amounts of data that are typically affected by several uncertainty sources. We propose herein a systematic framework to handle these uncertainties that takes advantage of recent advances made in modeling of uncertain LCA data and in optimization under uncertainty. Our strategy is based on a stochastic multi‐objective and multi‐scenario mixed‐integer nonlinear programming (MINLP) approach in which the uncertain parameters are described via scenarios. We investigate the use of two stochastic metrics: (i) the environmental impact in the worst case; and (ii) the environmental downside risk. We demonstrate the capabilities of our approach through its application to a generic complex industrial network in which we consider the uncertainty of some key life cycle inventory (LCI) parameters. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T11:06:54.416577-05:
      DOI: 10.1002/aic.14385
       
  • Foam electrospinning: A multiple jet, needle‐less process for
           nanofiber production
    • Authors: Alina K. Higham; Christina Tang, Alexandra M. Landry, Monty C. Pridgeon, Esther M. Lee, Anthony L. Andrady, Saad A. Khan
      Pages: n/a - n/a
      Abstract: We present a multiple jet, needle‐less process to fabricate electrospun nanofibers from foamed columns, produced by injecting compressed gas through a porous surface into polymer solutions, capable of circumventing syringe electrospinning shortcomings such as needle clogging and restrictions in production rate. Using polyvinyl alcohol and poly‐ethylene oxide as model systems, we identify key design, processing, and solution parameters for producing uniform fibers. Increasing electrode surface area produces thicker mats, suggesting charge distribution through the bulk foam facilitates electrospinning. Similar trends between foam and syringe electrospinning are observed for collection distance, electric field strength, and polymer concentration. Interestingly, the empirical correlation between polymer entanglement and fiber formation are found to be similar for both foam and traditional needle electrospinning, but the fiber crystallinity shows enhancement with foam electrospinning. In addition, foam electrospinning with a PEO‐non‐ionic surfactant system yields two orders of magnitude increase in production rate compared to syringe electrospinning. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T11:02:27.829891-05:
      DOI: 10.1002/aic.14381
       
  • Reduction of nonspecific binding for cellular imaging using quantum dots
           conjugated with Vitamin E
    • Authors: Jie Pan; Dong Wan, Yuxia Bian, Fengmin Jin, Tuo Wang, Yugao Guo, Jinlong Gong
      Pages: n/a - n/a
      Abstract: Quantum dots (QDs) as luminescence probes play an important role in the field of life sciences and medicine in recent decades. However, hydrophobic QDs have many limitations in applications for biological imaging such as insolubility in aqueous solutions and nonspecific binding to cellular membranes and so on. This paper describes the design and synthesis of D‐□‐tocopheryl polyethylene glycol 3350 succinate (TPGS3350) ‐conjugated QDs (TPGS3350‐QDs) NPs for effective reduction of nonspecific cellular binding of QDs for biological imaging. TPGS3350 with PEG3350 group was used in order to enhance the stabilization and water solubility of QDs, and reduce nonspecific cellular binding of NPs with the function of long‐chain PEG3350. We have demonstrated that TPGS3350‐QDs NPs show good stability and dispersion in aqueous solutions and that small amount of TPGS3350‐QDs NPs were nonspecific bound with MCF‐7 cells in comparison of MAA‐coated QDs NPs, which confirmed TPGS3350 can efficiently reduce nonspecific cellular binding due to the effect of PEG3350 in TPGS3350. The nonspecific binding of TPGS3350‐QDs NPs was also found to be much lower than that of TPGS‐QDs NPs. The developed TPGS3350‐QDs NPs in this study could be a promising tool for molecular imaging such as in vivo cell trafficking studies. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T10:57:04.939946-05:
      DOI: 10.1002/aic.14382
       
  • Global sensitivity analysis applied to drying models for one or a
           population of granules
    • Authors: Séverine Thérèse F.C. Mortier; Krist V. Gernaey, Thomas De Beer, Ingmar Nopens
      Pages: n/a - n/a
      Abstract: The development of mechanistic models for pharmaceutical processes is of increasing importance due to a noticeable shift towards continuous production in the industry. Sensitivity analysis is a powerful tool during the model building process. A Global Sensitivity Analysis (GSA), exploring sensitivity in a broad parameter space, is performed to detect the most sensitive factors in two models, i.e. one for drying of a single granule and one for the drying of a population of granules (using PBM), which was extended by including the gas velocity as extra input compared to our earlier work. β2 was found to be the most important factor for the single particle model which is useful information when performing model calibration. For the PBM‐model, the granule radius and gas temperature were found to be most sensitive. The former indicates that granulator performance impacts drying behavior, the latter is informative with respect to the variables that primarily need to be controlled during continuous operation. In addition, several GSA techniques are analyzed and compared with respect to the correct conclusion and computational load. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T10:56:59.545255-05:
      DOI: 10.1002/aic.14383
       
  • Simulations of solid‐liquid scalar transfer for a spherical particle
           in laminar and turbulent flow
    • Authors: J.J. Derksen
      Pages: n/a - n/a
      Abstract: Scalar transfer from a solid sphere to a surrounding liquid has been studied numerically. The simulation procedure involves full hydrodynamic resolution of the solid‐liquid interaction, and the flow (laminar and turbulent) of the carrier fluid by means of the lattice‐Boltzmann method. Scalar transport is solved with a finite volume method on Coupled Overlapping Domains (COD): an outer domain discretized with a cubic grid, and a shell around the solid sphere with a spherical grid with fine spacing in the radial direction. The shell is needed given the thin scalar boundary layer around the sphere that is the result of high Schmidt numbers (up to Sc=1,000). After assessing the COD approach for laminar benchmark cases, it is applied to a sphere moving through homogeneous isotropic turbulence with the sphere radius larger (by typically a factor of 10) than the Kolmogorov length scale so that it experiences an inhomogeneous hydrodynamic environment. This translates in pronounced scalar concentration variations and transfer rates over the sphere's surface. Overall scalar transfer coefficients are compared to those derived from classical Sherwood number correlations. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-23T10:45:31.756883-05:
      DOI: 10.1002/aic.14384
       
  • Control of the permeability of a porous media using a thermally sensitive
           polymer
    • Authors: Alexis Tran‐Viet; Alexander F. Routh, Andrew W. Woods
      Pages: n/a - n/a
      Abstract: Experiments explore the reduction in permeability of a porous bead pack when a suspension of thermally responsive polymer is injected and the temperature then increased above the thermal activation temperature. The change in permeability is greater with higher polymer concentration, provided that the ionic concentration of the solution is sufficient for floc formation. The time for activation of the blocking effect is within tens of seconds to minutes of when the polymer solution is heated. This is consistent with the timescale for diffusion‐limited aggregation, although the detailed value depends on the geometry and polymer concentration. Dynamical experiments demonstrate that once the porous media is blocked, adding additional polymer has no effect. The mechanism for permeability reduction may be modeled in the context of a pore‐network model, and we build a simple model to illustrate the permeability reduction as a function of the fraction of pores links which are blocked. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T12:05:34.427453-05:
      DOI: 10.1002/aic.14352
       
  • Oscillatory shear rheology of dilute solutions of flexible polymers
           interacting with oppositely charged particles
    • Authors: Rangarajan Radhakrishnan; Patrick T. Underhill
      Pages: n/a - n/a
      Abstract: Fluids with both attractions and repulsions among its constituents can exist in multiple states depending on nature of the interactions. An external flow can induce such systems to transition between the different states, such as the globule‐stretch transition for polymers in poor solvents. In this study, we perform Brownian dynamics simulations of a dilute solution of polymers and colloids interacting via short‐ranged potentials. For some values of the strength and range of interactions, compact structures of polymers and colloids are formed. An external flow is capable of pulling these globules apart, causing the polymers to stretch at a critical shear rate. In oscillatory shear, the shear rate can cycle between being above and below this critical shear rate leading to interesting dynamics. These dynamics are quantified using the rheological response in large amplitude oscillatory shear (LAOS). © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T07:17:32.290097-05:
      DOI: 10.1002/aic.14380
       
  • Influence of ash agglomerating fluidized bed reactor scale‐up on
           coal gasification characteristics
    • Authors: Yuncai Song; Jie Feng, Yalong Jia, Wenying Li, Yitian Fang
      Pages: n/a - n/a
      Abstract: To study the influence of fluidized‐bed reactor scale‐up on coal gasification characteristics, a model of the ash agglomerating fluidized bed reactor has been developed using an equivalent reactor network method. With the reactor network model, the scale‐up effects of a gasifier were studied in terms of the characteristics of the chemical reactions in the jet zone, the annulus dense‐phase zone and the freeboard zone. Results showed that the changes occurred in the inequality proportion of the volume of the jet zone during the reactor scale‐up. Taking into consideration the utilization of a portion of the backflow gas, the expansion of the jet zone volume and the coal particle residence time, the temperature of the jet zone was increased from 1592 K to 1662 K. Also, both the annulus dense‐phase zone temperature and the freeboard zone temperature decreased, causing subsequent decrease in the carbon conversion efficiency. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T07:17:22.817994-05:
      DOI: 10.1002/aic.14379
       
  • Production of aromatics by catalytic fast pyrolysis of cellulose in a
           bubbling fluidized bed reactor
    • Authors: Pranav U. Karanjkar; Robert J. Coolman, Michael T. Blatnik, Saba Almalkie, Stephen M. BruynKops, T. J. Mountziaris, William C. Conner, George W. Huber
      Pages: n/a - n/a
      Abstract: Catalytic Fast Pyrolysis (CFP) of cellulose was studied at 500°C using a ZSM‐5 catalyst in a bubbling fluidized bed reactor constructed from a 4.92‐cm ID pipe. Inert gas was fed from below through the distributor plate and from above through a vertical feed tube along with cellulose. Flowing 34% of the total fluidization gas through the feed tube led to the optimal mixing of the pyrolysis vapors into the catalyst bed, which experimentally corresponded to 29.5% carbon aromatic yield. Aromatic yield reached a maximum of 31.6% carbon with increasing gas residence time by changing the catalyst bed height. Increasing the hole‐spacing in the distributor plate was shown to have negligible effect on average bubble diameter and hence did not change the product distribution. Aromatic yields of up to 39.5% carbon were obtained when all studied parameters were optimized. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T07:06:04.31723-05:0
      DOI: 10.1002/aic.14376
       
  • Modeling and Control of Solar Grade Silicon Production in a Fluidized Bed
           Reactor
    • Authors: Juan Du; Soham Dutta, B. Erik Ydstie
      Pages: n/a - n/a
      Abstract: A multi‐scale model predicts silicon production yield and powder loss in a fluidized bed reactor for solar silicon production. The reaction module calculates the silicon vapor deposition and powder scavenging rates. A computational fluid dynamics model predicts temperature and bed density. A population balance model calculates the particle mass distribution functions on silicon yield. The model results are validated against industrial data. Furthermore, we conduct a sensitivity analysis to investigate the effect of gas flow rate and inlet silane concentration. Finally a control strategy is proposed to maintain the process at the desired operating point. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T06:42:43.782157-05:
      DOI: 10.1002/aic.14378
       
  • Hydrodynamic feedback on bubble breakup at a T‐junction within an
           asymmetric loop
    • Authors: Taotao Fu; Youguang Ma, Huai Z. Li
      Pages: n/a - n/a
      Abstract: This article presents bubble breakup at a microfluidic T‐junction by taking into consideration the hydrodynamic feedback at the downstream channels. Experiments are conducted in square microchannels with 400 μm in width. The splitting ratio of the bubble size in the bifurcations varies non‐monotonically with the flow rate ratio of gas/liquid phases, and it is also affected by the liquid viscosity. A critical size of the mother bubble determines the variation trend of the splitting ratio of bubble size with flow rates of both phases and the liquid viscosity, which is related to the different breakup mechanisms for long and short bubbles at the junction and the different additional resistances induced by long and short bubbles in downstream channels. A theoretical model is proposed to predict the tailoring size of bubbles at the T‐junction by taking into account of the additional resistance in the presence of bubbles in downstream channels. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-20T06:30:24.878699-05:
      DOI: 10.1002/aic.14377
       
  • Simulations of scalar dispersion in fluidized solid‐liquid
           suspensions
    • Authors: J.J. Derksen
      Pages: n/a - n/a
      Abstract: Direct, particle‐resolved simulations of solid‐liquid fluidization with the aim of quantifying dispersion have been performed. In addition to simulating the multiphase flow dynamics (that is dealt with by a lattice‐Boltzmann method coupled to an event‐driven hard‐sphere algorithm), a transport equation of a passive scalar in the liquid phase has been solved by means of a finite‐volume approach. The spreading of the scalar □ as a consequence of the motion of the fluidized, monosized spherical particles that agitate the liquid □ is quantified through dispersion coefficients. Particle self‐diffusivities have also been determined. Solids volume fractions were in the range 0.2 □ 0.5, whereas single‐sphere settling Reynolds numbers varied between approximately 3 and 20. The dispersion processes are highly anisotropic with lateral spreading much slower (by one order of magnitude) than vertical spreading. Scalar dispersion coefficients are of the same order of magnitude as particle self‐diffusivities. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-18T02:54:53.798371-05:
      DOI: 10.1002/aic.14372
       
  • Effect of fiber structure on yield stress during enzymatic conversion of
           cellulose
    • Authors: Emilio J. Tozzi; David M. Lavenson, Maria Cardona, Nardrapee Karuna, Tina Jeoh, Michael J. McCarthy, Robert L. Powell
      Pages: n/a - n/a
      Abstract: Enzymatic hydrolysis of cellulose for conversion to chemicals or fuels presents engineering challenges due to the large changes in suspension viscosity and yield stress that occur. A flow reactor with an on‐line rheometer was used to investigate the role of changes in fiber structure on rheology. The evolution of the suspension yield stress was compared to amount of soluble sugars released and changes in fiber length and width. A model was constructed that links the yield stress, conversion and fiber shape. These results provide insights into the relationship between fiber structure and transport properties during the early stages of hydrolysis of cellulosic biomass. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-17T02:19:22.579439-05:
      DOI: 10.1002/aic.14374
       
  • A model‐based approach to the automatic diagnosis of Von Willebrand
           disease
    • Authors: Federico Galvanin; Massimiliano Barolo, Roberto Padrini, Alessandra Casonato, Fabrizio Bezzo
      Pages: n/a - n/a
      Abstract: Von Willebrand disease (VWD) is the most common inherited coagulation disorder to be seen in humans. It originates from a deficiency and/or dysfunction of the von Willebrand factor (VWF), a large multimeric glycoprotein playing a central role in the hemostasis process. VWD occurs in a large variety of forms, and its symptoms may range from sporadic nosebleeds and mild bleeding from small lesions in skin, to acute thrombocytopenia or prolonged bleeding episodes. Diagnosing VWD may be complicated because of the heterogeneous nature of the disorder. Two mechanistic models of VWD are proposed in this paper, and their performance is assessed using clinical data. Models allow for the automatic detection of the disease, as well as for a quantitative assessment of VWF multimer distribution patterns, thus elucidating the critical pathways involved in the disease recognition and characterisation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-17T02:14:10.522764-05:
      DOI: 10.1002/aic.14373
       
  • Obtaining model‐independent growth rates from experimental data of
           dry thermal oxidation of silicon
    • Authors: Y Leong Yeow; Jong‐Leng Liow, Yee‐Kwong Leong
      Pages: n/a - n/a
      Abstract: Empirical time‐oxide layer thickness data of dry thermal oxidation of silicon were converted numerically into instantaneous growth rates by Tikhonov regularization. These growth rates are independent of any assumed kinetics of oxidation or functional form of the original data and can therefore be used in model testing of this important industrial process. A number of numerical issues in the Tikhonov regularization computation, e.g. the expected monotonic decrease in growth rate with time and the large time span of some of the data sets, are addressed. Numerical results indicate that kinetic data presented in the form of growth rate‐oxide layer thickness plots are more sensitive than the traditional time‐oxide thickness plots for use in model testing and for parameter determination. The advantages of this new approach are demonstrated by three case studies covering the complete oxide thickness spectrum of interest to the microelectronic industry. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-17T02:01:24.133771-05:
      DOI: 10.1002/aic.14375
       
  • Photochemical and acoustic interactions of biochar with CO2 and H2O:
           Applications in power generation and CO2 capture
    • Authors: Wei‐Yin Chen; Daniell L. Mattern, Eneruvie Okinedo, James Corbett Senter, Alec A. Mattei, Connor W. Redwine
      Pages: n/a - n/a
      Abstract: A critical literature review suggests that carbonaceous compounds react with (CO2 +H2O) mixture through thermal, photochemical, and sonochemical/sonophysical routes. A biochar was selected for studying these effects at 60°C and 1 atm for its potential benefits on power generation and CO2 capture. All treatments remove sizable minerals (K, Na, and Si) detrimental in power generation, and introduce carbon (up to 16% of original carbon in biochar) into the biochar matrix. Most treatments show increased hydrogen (up to 24%). Treatments lead to notable increased heating value of biochar (up to 50%). Treated biochars show increase (up to 19 fold) in internal surface area. The ultrasound energy output is a fraction of the increased heating value. Thus, pretreatment is potentially attractive for increasing the energy efficiency in combustion and gasification. Moreover, better understandings of the salient reactions of these processes will be advantageous for the development of advanced adsorbents for CO2 capture. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T22:34:16.320297-05:
      DOI: 10.1002/aic.14347
       
  • Visualization study of flow condensation in hydrophobic microchannels
    • Authors: Yongping Chen; Chaoqun Shen, Mingheng Shi, George P. Peterson
      Pages: n/a - n/a
      Abstract: A visualization study on flow condensation in hydrophobic rectangular silicon microchannels with hydraulic diameter of approximately 150 μm is conducted. Thin Au film with thickness of 200 nm is sputtered on channel surfaces to create a hydrophobic surface with an equilibrium contact angle of approximately 96°. In addition to traditional droplet flow, droplet‐annular compound flow, droplet‐injection compound flow, and droplet‐bubble/slug compound flow are also observed. The results indicate that injection location is postponed, and injection frequency increases with increasing inlet vapor Reynolds number and condensate Weber number. An empirical correlation of the injection location and injection frequency are presented and discussed. In particular, for a larger inlet vapor Reynolds number, the injection flow is closer to the channel outlet and the condensation heat transfer is enhanced. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T22:10:28.639777-05:
      DOI: 10.1002/aic.14319
       
  • Robust and high performance pressure retarded osmosis hollow fiber
           membranes for osmotic power generation
    • Authors: Gang Han; Tai‐Shung Chung
      Pages: n/a - n/a
      Abstract: Novel fabrication perspectives have been demonstrated to molecularly construct robust hollow fiber membrane supports for high performance thin‐film composite (TFC) pressure retarded osmosis (PRO) membranes. For the first time, we found that the desirable hollow fiber supports should possess high stretch resistance and acceptable ductility. The microstructure strength of the hollow fiber support may have more weights on overall robustness of the TFC PRO membranes than the apparent cross‐section morphology. Effectively manipulating the kinetics of phase inversion during spinning by maneuvering bore fluid chemistry, and polymer solution composition is a promising method to tailor the strength of hollow fiber supports. Prestabilization of the TFC membranes at elevated lumen pressures can significantly improve their PRO performance. The newly developed TFC PRO hollow fiber membranes exhibit a power density as high as 16.5 W/m2 and a very low specific reverse salt flux (Js/Jw) of 0.015 mol/L at a hydraulic pressure of 15 bar using synthetic seawater brine (1.0 M NaCl) as the draw solution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T21:47:41.877362-05:
      DOI: 10.1002/aic.14342
       
  • Speed of sound of ionic liquids: Database, estimation, and its application
           for thermal conductivity prediction
    • Authors: Ke‐Jun Wu; Qiao‐Li Chen, Chao‐Hong He
      Pages: n/a - n/a
      Abstract: Speed of sound is an important thermodynamic property of ionic liquids (ILs) and always chosen as a source to determine other properties. A database for the speed of sound of pure ILs created by collecting experimental data from literature covering the period from 2005 to 2013 is presented. The effects of temperature and the alkyl chain length on the speed of sound are discussed and a second‐order corresponding states group contribution method is developed to estimate the speed of sound. An average absolute deviation (AAD) of 2.34% has been obtained. This method offers a simple but reliable approach to estimate the speed of sound of new ILs. Finally, the speed of sound is used to determine the thermal conductivity of ILs based on the Bridgman theory. The calculated values of thermal conductivity show a good agreement with the experimental ones with an AAD of 3.91%. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T17:32:44.47199-05:0
      DOI: 10.1002/aic.14346
       
  • Sustainable process design and synthesis of hydrocarbon biorefinery
           through fast pyrolysis and hydroprocessing
    • Authors: Qiao Zhang; Jian Gong, Matthew Skwarczek, Dajun Yue, Fengqi You
      Pages: n/a - n/a
      Abstract: The process design and synthesis of hydrocarbon biorefinery, which is composed of fast pyrolysis, biocrude collection, hydroprocessing and hydrogen production sections, under economic and environmental considerations are concerned. A superstructure is developed that includes multiple process alternatives in each stage of the process flow diagram. A bi‐criteria mixed integer nonlinear programming model is proposed to maximize the economic performance measured by the net present value and minimize the global warming potential according to life cycle assessment procedures. The bi‐criteria mixed integer nonlinear programming model is solved with the ε‐constraint method, and the resulting Pareto curve reveals the trade‐off between the economic and environmental performance of the process. The two selected “good choice” optimal designs indicate net present values of 573 and 93.6 $MM (unit costs of $3.43 and $5.26 per gallon of gasoline equivalent), corresponding to global warming potentials of 100 and 53 kton CO2 equivalent per year (unit greenhouse emissions of 1.95 and 2.04 kg CO2 per gallon of gasoline equivalent), respectively. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T17:00:53.444569-05:
      DOI: 10.1002/aic.14344
       
  • A bilevel NLP sensitivity‐based decomposition for dynamic
           optimization with moving finite elements
    • Authors: Weifeng Chen; Zhijiang Shao, Lorenz T. Biegler
      Pages: n/a - n/a
      Abstract: Optimal control has guided numerous applications in chemical engineering, and exact determination of optimal profiles is essential for operation of separation and reactive processes, and operating strategies and recipe generation for batch processes. Here, a simultaneous collocation formulation based on moving finite elements is developed for the solution of a class of optimal control problems. Novel features of the algorithm include the direct location of breakpoints for control profiles and a termination criterion based on a constant Hamiltonian profile. The algorithm is stabilized and performance is significantly improved by decomposing the overall nonlinear programming (NLP) formulation into an inner problem, which solves a fixed element simultaneous collocation problem, and an outer problem, which adjusts the finite elements based on several error criteria. This bilevel formulation is aided by a NLP solver (the interior point optimizer) for both problems as well as an NLP sensitivity component, which provides derivative information from the inner problem to the outer problem. This approach is demonstrated on 11 dynamic optimization problems drawn from the optimal control and chemical engineering literature. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T16:45:00.823423-05:
      DOI: 10.1002/aic.14339
       
  • Kinetic modeling of hemicellulose hydrolysis in the presence of
           homogeneous and heterogeneous catalysts
    • Authors: Tapio Salmi; Dmitry Yu. Murzin, Päivi Mäki‐Arvela, Bright Kusema, Bjarne Holmbom, Stefan Willför, Johan Wärnå
      Pages: n/a - n/a
      Abstract: Kinetic models were developed for the hydrolysis of O‐acetyl‐galactoglucomannan (GGM), a hemicellulose appearing in coniferous trees. Homogeneous and heterogeneous acid catalysts hydrolyze GGM at about 90°C to the monomeric sugars galactose, glucose, and mannose. In the presence of homogeneous catalysts, such as HCl, H2SO4, oxalic acid, and trifluoroacetic acid, the hydrolysis process shows a regular kinetic behavior, while a prominent autocatalytic effect was observed in the presence of heterogeneous cation‐exchange catalysts, Amberlyst 15 and Smopex 101. The kinetic models proposed were based on the reactivities of the nonhydrolyzed sugar units and the increase of the rate constant (for heterogeneous catalysts) as the reaction progresses and the degree of polymerization decreases. General kinetic models were derived and special cases of them were considered in detail, by deriving analytical solutions for product distributions. The kinetic parameters, describing the autocatalytic effect were determined by nonlinear regression analysis. The kinetic model described very well the overall kinetics, as well as the product distribution in the hydrolysis of water soluble GGM by homogeneous and heterogeneous catalysts. The modelling principles developed in the work can be in principle applied to hydrolysis of similar hemicelluloses as well as starch and cellulose. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T14:47:00.180376-05:
      DOI: 10.1002/aic.14311
       
  • Just‐in‐time reorganized PCA integrated with SVDD for chemical
           process monitoring
    • Authors: Qingchao Jiang; Xuefeng Yan
      Pages: n/a - n/a
      Abstract: Although principal component analysis (PCA) is widely used for chemical process monitoring, improvements in the selection of principal components (PCs) are still needed. Given that the determination of complicated and changing fault information is not guaranteed using offline‐selected PCs, this study proposes a just‐in‐time reorganized PCA model that objectively selects the PCs online for process monitoring. The importance of the PCs is evaluated online by kernel density estimation. The PCs indicating more varied information are then selected to reorganize the PCA model. Given that the most useful fault information is concentrated, support vector data description is used to replace traditional statistics, thereby relaxing the Gaussian assumption of the process data. The monitoring performances of the proposed method are evaluated under three cases. Compared with conventional PCA methods, more varied information is captured online, and the monitoring performances are improved. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T14:07:30.247447-05:
      DOI: 10.1002/aic.14335
       
  • Distribution of large biomass particles in a sand‐biomass fluidized
           bed: Experiments and modeling
    • Authors: Farzam Fotovat; Jamal Chaouki, Jeffrey Bergthorson
      Pages: n/a - n/a
      Abstract: The axial distribution of large biomass particles in bubbling fluidized beds comprised of sand and biomass is investigated in this study. The global and local pressure drop profiles are analyzed in mixtures fluidized at superficial gas velocities ranging from 0.2 to 1 m/s. In addition, the radioactive particle tracking technique is used to track the trajectory of a tracer mimicking the behavior of biomass particles in systems consisting of 2, 8, and 16% of biomass mass ratio. The effects of superficial gas velocity and the mixture composition on the mixing/segregation of the bed components are explored by analyzing the circulatory motion of the active tracer. Contrary to low fluidization velocity (U = 0.36 m/s), biomass circulation and distribution are enhanced at U = 0.64 m/s with increasing the load of biomass particles. The axial profile of volume fraction of biomass along the bed is modeled on the basis of the experimental findings. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-16T12:29:38.146074-05:
      DOI: 10.1002/aic.14337
       
  • Effects of 3D microwell culture on initial fate specification in human
           embryonic stem cells
    • Authors: Cheston Hsiao; Matthew Tomai, Jeremy Glynn, Sean P. Palecek
      Pages: n/a - n/a
      Abstract: Several studies have demonstrated that 3D culture systems influence human embryonic stem cell (hESC) phenotypes and fate choices. However, the effect that these microenvironmental changes have on signaling pathways governing hESC behaviors is not well understood. Here, we have used a 3D microwell array to investigate differences in activation of developmental pathways between 2D and 3D cultures of both undifferentiated hESCs and hESCs undergoing initial differentiation in embryoid bodies (EBs). We observed increased induction into mesoderm and endoderm and differences in expression of genes from multiple signaling pathways that regulate development, including Wnt/β‐catenin, TGF‐β superfamily, Notch and FGF during EB‐mediated differentiation, in 3D microwells as compared with the 2D substrates. In undifferentiated hESCs, we also observed differences in epithelial‐mesenchymal transition phenotypes and the TGFβ/BMP pathway between cultures in 3D and 2D. These results illustrate that 3D culture influences multiple pathways that may regulate the differentiation trajectories of hESCs. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2014-01-16T07:47:05.796498-05:
      DOI: 10.1002/aic.14351
       
  • Rheological predictions of network systems swollen with entangled solvent
    • Authors: Maria Katzarova; Marat Andreev, Yelena R. Sliozberg, Randy A. Mrozek, Joseph L. Lenhart, Jan W. Andzelm, Jay D. Schieber
      Pages: n/a - n/a
      Abstract: The mechanical properties of a cross‐linked polydimethylsiloxane (PDMS) network swollen with non‐reactive entangled PDMS solvent was previously studied experimentally [Mrozek et al. Polymer 2011, 52, 3422‐3430]. In this paper we use the discrete slip‐link model (DSM) to predict its linear and non‐linear rheology. Model parameters are obtained from the dynamic modulus data of pure solvent. Network rheology predictions also require an estimate of the fraction and architecture of dangling or inactive strands in the network, which is not directly measurable. The active strand fraction is estimated from dynamic modulus measurements and the molecular weight is adjusted to fit the dynamic modulus data. Then the non‐linear rheology can be predicted without adjustments. These successful predictions strongly suggest that the observed rheological modification in the swollen blend arises from the constraint dynamics between the network chains and the dangling ends. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-15T15:30:09.947994-05:
      DOI: 10.1002/aic.14370
       
  • Single step ultrasonic synthesis of biodiesel from crude Jatropha curcas
           oil
    • Authors: Hanif A. Choudhury; Pulkit Srivastava, Vijayanand S. Moholkar
      Pages: n/a - n/a
      Abstract: This paper reports investigation of a novel single‐step process with chlorosulfonic acid catalyst for ultrasonic biodiesel synthesis using feedstock with high FFA content. Jatropha curcas oil has been used as the model feedstock with methanol as alcohol. The distinct merit of chlorosulfonic acid is that it catalyzes both esterification and transesterification reactions. Moreover, chlorosulfonic acid also counteracts inhibition caused by water formed during esterification, which is the cause for very slow kinetics of acid catalyzed transesterification. In addition, sonication of the reaction mixture also causes strong micro‐mixing and emulsification that enhances the transesterification kinetics. Statistical optimization of the process shows 93% yield for 8.5 wt% catalyst, 20:1 alcohol to oil molar ratio and temperature of 333 K. Peculiar feature of this process is that high yield is seen at moderate temperature and molar ratio, which are much smaller than that for conventional sulphuric acid catalyzed processes. The activation energy for the process (57 kJ/mol) is at least 3× lower than the energy for sulphuric acid catalyzed transesterification. The thermodynamic analysis reveals that the net Gibbs energy change for the single step process is almost same as that for sulphuric acid catalyzed process. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-15T15:30:04.701604-05:
      DOI: 10.1002/aic.14371
       
  • Effects of excluded volume and hydrodynamic interactions on the behavior
           of isolated bead‐rod polymer chains in shearing flow
    • Authors: Indranil Saha Dalal; Chih‐Chen Hsieh, Alex Albaugh, Ronald G. Larson
      Pages: n/a - n/a
      Abstract: A detailed study of the effects of hydrodynamic interaction (HI) and excluded volume (EV), on isolated bead‐rod chains in shear flows, where the “rods” are mimicked by stiff Fraenkel springs is presented. It is observed that the deformation behavior at weak and intermediate shear rates is qualitatively similar to that observed for polymer chains in the absence of EV and HI, while that at high‐shear rates is sensitive to modeling details and chain resolution. Our simulations with varying degrees of resolution reveal universality in chain behavior in the presence of EV (without HI), while the onset of the transition to a compressed chain in the presence of HI (without EV) shifts to higher shear rates with increasing chain resolution. The results also highlight the success of the bead‐spring models in predicting the chain behavior in shear flows in the presence of HI, when the HI parameter is appropriately chosen. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T17:00:36.458104-05:
      DOI: 10.1002/aic.14317
       
  • Effect of reaction conditions on supercritical hexanes mediated higher
           alcohol synthesis over a CuCoZn catalyst
    • Authors: Rui Xu; Sihe Zhang, Charlotte Stewart, Ed Durham, Mario R. Eden, Christopher B. Roberts
      Pages: n/a - n/a
      Abstract: Higher alcohol synthesis (HAS) from syngas over a CuCo based catalyst was investigated under supercritical hexanes conditions. The effects of hexanes/syngas molar ratio, H2/CO molar ratio, and gas hourly space velocity (GHSV) on gas‐phase HAS and supercritical hexanes‐phase HAS (SC‐HAS) were investigated. The CO conversion remained relatively constant with increases in the hexanes/syngas molar ratio, whereas the CH4 selectivity decreased. Higher alcohol productivity was found to increase monotonically with an increase in the hexanes/syngas molar ratio. Productivity of higher alcohols increased with an increase in the H2/CO ratio under the gas‐phase conditions. An opposite trend in higher alcohol productivity with H2/CO was observed in SC‐HAS. Further experiments were performed using argon as the reaction medium for comparison with the supercritical hexanes medium results. The enhanced higher alcohol productivity observed in this system can be attributed to improved extraction of alcohol products from the catalyst pores under the supercritical conditions. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T16:49:06.647605-05:
      DOI: 10.1002/aic.14333
       
  • CO2 capture by pyrrolidine: Reaction mechanism and mass transfer
    • Authors: Alicia García‐Abuín; Diego Gómez‐Díaz, José M. Navaza, Antonio Rumbo
      Pages: n/a - n/a
      Abstract: A new carbon dioxide capture process by means of gas–liquid absorption using pyrrolidine aqueous solutions in a bubble column reactor obtaining suitable results in comparison with other commonly used amines is analyzed. The influence of several operation variables such as amine concentration and gas flow rate has been studied. Carbon dioxide mass‐transfer rate data have shown a different behavior than other amine‐based systems because a constant value in absorption rate was observed in the middle of batch experiments. 13C and 1H NMR spectroscopy studies were performed to analyze the species present during the experiments. These data and the carbon dioxide loading allowed to explain the reaction mechanism existed between these reagents. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T16:34:41.420083-05:
      DOI: 10.1002/aic.14343
       
  • The viscous drag on solids moving through solids
    • Authors: Joe D. Goddard
      Pages: n/a - n/a
      Abstract: An extension of the theory of Ornstein (1906) and Nye (1967) for the drag force on circular wires and other solid bodies creeping through ice by means of pressure‐melting and regelation is provided. Nye's theory leads to a form of Stokes law, with rates controlled by heat conduction and lubrication flow in a thin water layer between ice and solid body. New analytical solutions are given for the corresponding drag force and torque on elliptical cylinders and spheroids for the special case of thermally thin water layers and for certain special forms of uncoupled translation and rotation that allow for single‐harmonic temperature fields. The present results differ from those proposed by Nye for general body shapes in the limit of negligible thermal resistance of the water layer. Also, the present results for the drag force on elliptic cylinders do not agree with the formulae derived by Tyvand and Bejan (1992) for small ellipticity. A brief review is given for various effects that might account for certain departures of the Nye theory from experiment on circular wires, in the hope that the present results may suggest simpler experiments aimed at systematic modification of the theory to account for such anomalies. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T16:05:50.563641-05:
      DOI: 10.1002/aic.14334
       
  • Distributed dissipative model predictive control for process networks with
           imperfect communication
    • Authors: Michael James Tippett; Jie Bao
      Pages: n/a - n/a
      Abstract: Results are developed to ensure stability of a dissipative distributed model predictive controller in the case of structured or arbitrary failure of the controller communication network; bounded errors in the communication may similarly be handled. Stability and minimum performance of the process network is ensured by placing a dissipative trajectory constraint on each controller. This allows for the interaction effects between units to be captured in the dissipativity properties of each process, and thus, accounted for by choosing suitable dissipativity constraints for each controller. This approach is enabled by the use of quadratic difference forms as supply rates, which capture detailed dynamic system information. A case study is presented to illustrate the results. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T14:08:57.999547-05:
      DOI: 10.1002/aic.14369
       
  • Electrohydrostatics of capillary switches
    • Authors: Krishnaraj Sambath; Osman A. Basaran
      Pages: n/a - n/a
      Abstract: A capillary switch is a system of two liquid drops, one sessile and the other pendant, obtained by overfilling a hole of radius R in a plate. When surface tension dominates gravity, the equilibrium shapes of the drops are spherical sections of equal radii. If the combined volume of the top VT and bottom VB drops exceeds 4πR3/3, the system has three equilibrium states of which two are stable. This bistability is exploited in applications by toggling the system between its two stable states. Here, we examine the effectiveness of using an electric field for toggling. Bifurcation diagrams are obtained that depict how the system's response varies with applied field strength E, and show loss of stability at turning points and the possibility of hysteresis. A phase diagram in E–(VT + VB) space is presented to readily infer when an electric field is an effective means for toggling. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-13T14:08:23.214367-05:
      DOI: 10.1002/aic.14367
       
  • The impact of shale gas in the chemical industry
    • Authors: Jeffrey J. Siirola
      Pages: n/a - n/a
      PubDate: 2014-01-13T08:18:08.895748-05:
      DOI: 10.1002/aic.14368
       
  • Characteristic scales of two‐dimensional turbulence in polymer
           solutions
    • Authors: Ruri Hidema; Hiroshi Suzuki, Shion Hisamatsu, Yoshiyuki Komoda
      Pages: n/a - n/a
      Abstract: An experimental study has been performed in order to investigate the relationship between the extensional viscosity of polymers and the turbulent drag reduction. Self‐standing flowing soap film was used to generate two‐dimensional (2D) turbulent flow in order to eliminate shear stress. Two types of polymers having different flexibilities were added to the 2D turbulence. The effects of these polymers were visualized by the interference pattern of flowing soap films. The vortex deformation by adding polymers was analyzed by Fourier transformation and wavelet transformation. The scaling exponents of the power spectrum of interference patterns indicate that the mechanism of turbulence laminarization due to the extensional viscosity is anisotropic. A wavelet analysis reveals the high and low fluctuations of the polymer added flow. Results from wavelet analysis indicate disappearing of original vortices, and appearing of new structures in low frequency in 2D flow. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-10T17:18:51.798059-05:
      DOI: 10.1002/aic.14364
       
  • Separation of ultrasonic contributions and energy utilization
           characteristics of ultrasonic regeneration
    • Authors: Kun Yang; Ye Yao, Shiqing Liu, Beixing He
      Pages: n/a - n/a
      Abstract: The method of applying ultrasound to silica gel regeneration process has been proved to be able to improve regeneration efficiency and reduce regeneration temperature. The average regeneration rate can be increased by 10% and the benefits should owe to the special ‘vibration effect’ and ‘heating effect’ induced by ultrasound. In this paper, a dynamic one‐dimensional mathematical model, validated by experiments, has been developed. It is then used to investigate energy utilization efficiency of the ultrasonic regeneration and respective contribution ratio of the two ultrasonic effects. The results show that the contribution ratio of ‘vibration effect’ dominates and the energy utilization efficiency of silica gel regeneration with ultrasound can be 1% higher. The ultrasonic regeneration is more energy‐saving when the contribution ratio of ‘vibration effect’ is greater. The results also show that the enhancement of regeneration brought by ultrasound is not a simple sum of their respective contribution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-09T14:02:13.087372-05:
      DOI: 10.1002/aic.14360
       
  • Moving horizon approach of integrating scheduling and control for
           sequential batch processes
    • Authors: Yunfei Chu; Fengqi You
      Pages: n/a - n/a
      Abstract: Online integration of scheduling and control is crucial to cope with process uncertainties. We propose a new online integrated method for sequential batch processes, where the integrated problem is solved to determine controller references rather than process inputs. Under a two‐level feedback loop structure, the integrated problem is solved in a frequency lower than that of the control loops. To achieve the goal of computational efficiency and rescheduling stability, a rolling horizon approach is developed. A reduced integrated problem in a re‐solving horizon is formulated, which can be solved efficiently online. Solving the reduced problem only changes a small part of the initial solution, guaranteeing rescheduling stability. The integrated method is demonstrated in a simulated case study. Under uncertainties of the control system disruption and the processing unit breakdown, the integrated method prevents a large loss in the production profit compared with the simple shifted rescheduling solution. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-01-09T13:51:24.020011-05:
      DOI: 10.1002/aic.14359
       
  • Hydrophobic Coating of Silicate Phosphor Powder Using Atmospheric Pressure
           Dielectric Barrier Discharge Plasma
    • Authors: Quang Hung Trinh; Sang Baek Lee, Young Sun Mok
      Pages: n/a - n/a
      Abstract: A stable super‐hydrophobic coating was successfully deposited on commercial silicate‐based orange phosphor by using atmospheric pressure dielectric barrier discharge plasma with hexamethyldisiloxane (HMDSO) and HMDSO/toluene mixture as precursors. Owning to the good optical properties, the deposited film acts not only as a hydrophobic protective layer but also as an anti‐reflection optical thin film capable of improving the phosphor photoluminescence efficiency. The plasma‐polymerized film based on Si‐O‐Si backbone containing methyl and phenyl non‐polar functional groups exhibited high water‐repellent characteristics. It was found that the water contact angle gradually increased with increasing the aging time and remained unchanged at about 140o after 1‐month aging. Besides, the thermal stability of the coated phosphor under high temperature condition was substantially enhanced by the aging. The findings of this work can contribute to improving the durability and reliability of the phosphor, eventually the long‐term stability of phosphor‐based light emitting diodes in practical applications. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2014-01-06T04:14:36.385301-05:
      DOI: 10.1002/aic.14356
       
  • Dependence of shear and concentration on fouling in a membrane bioreactor
           with rotating membrane discs
    • Authors: Mads K. Jørgensen; Malene T. Pedersen, Morten L. Christensen, Thomas R. Bentzen
      Pages: n/a - n/a
      Abstract: Rotating ceramic membrane discs were fouled with lab‐scale membrane bioreactors (MBR) sludge. Sludge filtrations were performed at varying rotation speeds and in different concentric rings of the membranes on different sludge concentrations. Data showed that the back transport expressed by limiting flux increased with rotation speed and distance from membrane center as an effect of shear. Further, the limiting flux decreased with increasing sludge concentration. A model was developed to link the sludge concentration and shear stress to the limiting flux. The model was able to simulate the effect of shear stress and sludge concentration on the limiting flux. The model was developed by calculating the shear rate at laminar flow regime at different rotation speeds and radii on the membrane. Furthermore, through the shear rate and shear stress, the non‐Newtonian behavior of MBR sludge was addressed. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2013-12-31T21:52:18.155584-05:
      DOI: 10.1002/aic.14302
       
  • Nanostructured high‐energy xLi2MnO3·(1‐x)LiNi0.5Mn0.5O2
           (0.3 ≤ x ≤ 0.6) cathode materials
    • Authors: Xiaofeng Zhang; Miklos Lengyel, Richard L. Axelbaum
      Pages: n/a - n/a
      Abstract: Nanostructured lithium‐manganese‐rich nickel‐manganese‐oxide xLi2MnO3·(1‐x)LiNi0.5Mn0.5O2 (0.3 ≤ x ≤ 0.6) composite materials were synthesized via spray pyrolysis using mixed nitrate precursors. All the materials showed a composite structure consisting of Li2MnO3 (C2/m) and LiNi0.5Mn0.5O2 (R3¯m) components, and the amount of Li2MnO3‐phase appeared to increase with x, as observed from XRD analysis. These composite materials showed a high‐discharge capacity of about 250 mAhg−1. In the range of x considered, the layered 0.5Li2MnO3·0.5LiNi0.5Mn0.5O2 materials displayed the highest capacity and superior cycle stability. Nonetheless, voltage suppression from a layered‐spinel phase transition was observed for all the composites produced. This voltage suppression was dependent of the amount of Li2MnO3 phase present in the composite structure. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2013-12-19T13:55:22.803125-05:
      DOI: 10.1002/aic.14287
       
  • Impact of gravity on the bubble‐to‐pulse transition in packed
           beds
    • Authors: Paul Salgi; Vemuri Balakotaiah
      Pages: n/a - n/a
      Abstract: A model based on two‐phase volume‐averaged equations of motion is proposed to examine the gravity dependence of the bubble‐to‐pulse transition in gas‐liquid cocurrent down‐flow through packed beds. As input, the model uses experimental correlations for the frictional pressure drop under both normal gravity conditions and in the limit of vanishing gravity, as well as correlations for the liquid‐gas interfacial area per unit volume of bed in normal gravity. In accordance with experimental observations, the model shows that, for a given liquid flow, the transition to the pulse regime occurs at lower gas‐flow rates as the gravity level or the Bond number is decreased. Predicted transition boundaries agree reasonably well with observations under both reduced and normal gravity. The model also predicts a decrease in frictional pressure drop and an increase in total liquid holdup with decreasing gravity levels. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2013-12-19T13:05:23.005002-05:
      DOI: 10.1002/aic.14300
       
  • Computational fluid dynamics based design of finned steam cracking
           reactors
    • Authors: Carl M. Schietekat; David J. Van Cauwenberge, Kevin M. Van Geem, Guy B. Marin
      Pages: n/a - n/a
      Abstract: The use of one‐dimensional reactor models to simulate industrial steam cracking reactors has been one of the main limiting factors for the development of new reactor designs and the evaluation of existing 3D reactor configurations. Therefore a three‐dimensional computational fluid dynamics approach is proposed in which the detailed free‐radical chemistry is for the first time accounted for. As a demonstration case the application of longitudinally and helicoidally finned tubes as steam cracking reactors was investigated under industrially relevant conditions. After experimental validation of the modeling approach, a comprehensive parametric study allowed to identify optimal values of the fin parameters, i.e. fin height, number of fins and helix angle to maximize heat transfer. Reactive simulations of an industrial Millisecond propane cracker were performed for four distinct finned reactors using a reaction network of 26 species and 203 elementary reactions. The start‐of‐run tube metal skin temperatures could be reduced by up to 50 K compared to conventionally applied tubular reactors when applying optimal fin parameters. Implementation of a validated coking model for light feedstocks shows that coking rates are reduced up to 50%. However, the increased friction and inner surface area lead to pressure drops higher by a factor from 1.22 to 1.66 causing minor but significant shifts in light olefin selectivity. For the optimized helicoidally finned reactor the ethene selectivity dropped, while propene and 1,3‐butadiene selectivity increased with a similar amount. The presented methodology can be applied in a straightforward way to other 3D reactor designs or can be extended to more complex feedstocks such as naphtha. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2013-12-18T05:56:06.791489-05:
      DOI: 10.1002/aic.14326
       
  • Continuous and scale‐up synthesis of high purity H2O2 by safe
           gas‐phase H2/O2 plasma reaction
    • Authors: Yanhui Yi; Juncheng Zhou, Jialiang Zhang, Tianlong Gao, Hongchen Guo
      Pages: n/a - n/a
      Abstract: This Letter reports a new generation of double dielectric barrier discharge (DDBD) reactor featured by a metal powder (MP) high voltage electrode. The MP high voltage electrode not only has excellent homogeneous discharge performance but also has the advantage of without regular maintenance. Therefore, the MP‐DDBD reactor was proved to be suitable for the uninterrupted and safe synthesis of high purity H2O2 aqueous solution with up to 65 wt% concentration from the H2/O2 mixture. The scale‐up synthesis of H2O2 was sucessfully attempted in an integrated device based on the MP‐DDBD reactor. The future practical H2O2 synthesizer based on the MP‐DDBD reactor will be small and movable, and therefore be convenient to supply high purity H2O2 on site for small scale users like semiconductor industry. © 2013 American Institute of Chemical Engineers AIChE J, 2013
      PubDate: 2013-12-18T05:46:49.129993-05:
      DOI: 10.1002/aic.14327
       
  • A globally convergent method for finding all steady‐state solutions
           of distillation columns
    • Authors: Ali Baharev; Arnold Neumaier
      Pages: 410 - 414
      Abstract: A globally convergent method is proposed that either returns all solutions to steady‐state models of distillation columns or proves their infeasibility. Initial estimates are not required. The method requires a specific but fairly general block‐sparsity pattern; in return, the computational efforts grow linearly with the number of stages in the column. The well‐known stage‐by‐stage (and the sequential modular) approach also reduces the task of solving high‐dimensional steady‐state models to that of solving a sequence of low‐dimensional ones. Unfortunately, these low‐dimensional systems are extremely sensitive to the initial estimates, so that solving them can be notoriously difficult or even impossible. The proposed algorithm overcomes these numerical difficulties by a new reparameterization technique. The successful solution of a numerically challenging reactive distillation column with seven steady‐states shows the robustness of the method. No published software known to the authors could compute all solutions to this difficult model without expert tuning. © 2013 American Institute of Chemical Engineers AIChE J 60: 410–414, 2014
      PubDate: 2013-12-11T12:24:13.653284-05:
      DOI: 10.1002/aic.14305
       
  • Turning wine (waste) into water: Toward technological advances in the use
           of constructed wetlands for winery effluent treatment
    • Authors: Craig Sheridan; Diane Hildebrand, David Glasser
      Pages: 420 - 431
      Abstract: The research presented in this article describes an investigation into the use of vegetated submerged reedbeds (VSR) as a practicable alternative for effluent treatment for small‐scale wine producers. In this study, we found that the hydraulic processes occurring within the VSR display significantly nonideal behavior. If the feed to the VSR was located on the surface the dead volume accounted for approximately 25% of the nonideal behavior of the system and bypass accounted for a further 6%. A preferential flow pattern was found within the VSR with the greatest flow occurring closest the surface and in the center, and the least at the sidewalls. We propose that the flow profile can be conceptualized as being hull shaped and found that this profile was the same for irregularly shaped gravel and for spherically shaped gelatinous beads. We, therefore, hypothesize that it is not dependent on the geometry of the VSR or the packing medium. © 2013 American Institute of Chemical Engineers AIChE J 60: 420–431, 2014
      PubDate: 2013-12-04T10:45:19.762552-05:
      DOI: 10.1002/aic.14297
       
  • Biomimetic biphasic 3‐D nanocomposite scaffold for osteochondral
           regeneration
    • Authors: Nathan J. Castro; Christopher M. O'Brien, Lijie Grace Zhang
      Pages: 432 - 442
      Abstract: Scaffold‐based interfacial tissue engineering aims to not only provide the structural and mechanical framework for cellular growth and tissue regeneration, but also direct cell behavior. Due to the disparity in composition of the osteochondral (cartilage and bone) interface, this work has developed a novel biomimetic biphasic nanocomposite scaffold integrating two biocompatible polymers containing tissue‐specific growth factor‐encapsulated core–shell nanospheres. Specifically, a poly(caprolactone) (PCL)‐based bone layer was successfully integrated with a poly(ethylene glycol) (PEG) hydrogel cartilage layer. In addition, a novel nanosphere fabrication technique for efficient growth factor encapsulation and sustained delivery via a wet coaxial electrospray technique was developed. Human bone marrow mesenchymal stem cell (hMSC) adhesion, osteogenic, and chondrogenic differentiation were evaluated. Our in vitro results showed significantly improved hMSC adhesion and differentiation in bone and cartilage layers, respectively. Studies have demonstrated promising results with novel biphasic nanocomposite scaffold for osteochondral tissue regeneration, thus, warranting further studies. © 2013 American Institute of Chemical Engineers AIChE J 60: 432–442, 2014
      PubDate: 2013-12-10T11:00:37.100255-05:
      DOI: 10.1002/aic.14296
       
  • Electrophoresis of pH‐regulated particles in the presence of
           multiple ionic species
    • Authors: Chien Hsu; Duu‐Jong Lee, Jyh‐Ping Hsu, Nan Wang, Shiojenn Tseng
      Pages: 451 - 458
      Abstract: An electrophoresis model taking account of the pH‐regulated nature of particles and the presence of multiple ionic species is proposed for arbitrary surface potential and double‐layer thickness. It successfully simulated the electrophoretic behavior of Fe3O4 nanoparticles in an aqueous NaCl solution with pH adjusted by HCl and NaOH. The estimated zeta potential is compared with those from the conventional models, Smoluchowski's, Hückel's, and Henry's formulas. Due to the violation of the assumption of low and constant surface potential, these formulas yielded appreciable deviations (e.g., 23–30 mV at pH 9). With the surface charge density measured by titration and the zeta potential by electrophoresis, the true surface potential is estimated through a triple‐layer model. The estimated true potential is typically 1.5–10 times larger than the zeta potential, implying that using the latter in relevant calculations (e.g., stability and critical coagulation concentration) might yield appreciable deviation. © 2013 American Institute of Chemical Engineers AIChE J 60: 451–458, 2014
      PubDate: 2013-11-08T16:57:14.69478-05:0
      DOI: 10.1002/aic.14276
       
  • Large‐eddy simulation modeling of turbulent flame synthesis of
           titania nanoparticles using a bivariate particle description
    • Authors: Yonduck Sung; Venkat Raman, Heeseok Koo, Maulik Mehta, Rodney O. Fox
      Pages: 459 - 472
      Abstract: Flame‐based synthesis of nanoparticles is an important chemical process used for the manufacturing of metal oxide particles. In this aerosol process, nanoparticle precursors are injected into a high‐temperature flame that causes precursor oxidation, nucleation, and subsequent growth of solid particles through a variety of processes. To aid computational design of the aerosol process, a large‐eddy simulation (LES) based computational framework is developed here. A flamelet‐based model is used to describe both combustion and precursor oxidation. The solid phase nanoparticle evolution is described using a bivariate number density function (NDF) approach. The high‐dimensional NDF transport equation is solved using a novel conditional quadrature method of moments (CQMOM) approach. Particle phase processes such as collision‐based aggregation, and temperature‐induced sintering are included in this description. This LES framework is used to study an experimental methane/air flame that used titanium tetrachloride to generate titania particles. The simulation results show that the evolution process of titania nanoparticles is largely determined by the competition between particle aggregation and sintering at downstream locations in the reactor. It is shown that the bivariate description improves the prediction of particle size characteristics, although the large uncertainty in inflow and operating conditions prevent a full scale validation. © 2013 American Institute of Chemical Engineers AIChE J 60: 459–472, 2014
      PubDate: 2013-11-19T12:23:17.106972-05:
      DOI: 10.1002/aic.14279
       
  • The effect of cohesive forces on the fluidization of aeratable powders
    • Authors: Janine E. Galvin; Sofiane Benyahia
      Pages: 473 - 484
      Abstract: The effects of cohesive forces of van der Waals type in the fluidization/defluidization of aeratable type A powders in the Geldart classification are numerically investigated. The effects of friction and particle‐size distribution (PSD) on some design‐significant parameters, such as minimum fluidization and bubbling velocities, are also investigated. For these types of particles, cohesive forces are observed as necessary to fully exhibit the role friction plays in commonly observed phenomena, such as pressure overshoot and hysteresis around minimum fluidization. This study also shows that a full‐experimental PSD consisting of a dozen particle sizes may be sufficiently represented by a few particle diameters. Reducing the number of particle types may benefit the continuum approach, which is based on the kinetic theory of granular flow, by reducing computational expense, while still maintaining the accuracy of the predictions. Published 2013 American Institute of Chemical Engineers AIChE J 60: 473–484, 2014
      PubDate: 2013-12-12T12:11:07.078417-05:
      DOI: 10.1002/aic.14307
       
  • A quality relevant non‐Gaussian latent subspace projection method
           for chemical process monitoring and fault detection
    • Authors: Junichi Mori; Jie Yu
      Pages: 485 - 499
      Abstract: Partial least‐squares (PLS) method has been widely used in multivariate statistical process monitoring field. The goal of traditional PLS is to find the multidimensional directions in the measurement‐variable and quality‐variable spaces that have the maximum covariances. Therefore, PLS method relies on the second‐order statistics of covariance only but does not takes into account the higher‐order statistics that may involve certain key features of non‐Gaussian processes. Moreover, the derivations of control limits for T2 and squared prediction error (SPE) indices in PLS‐based monitoring method are based on the assumption that the process data follow a multivariate Gaussian distribution approximately. Meanwhile, independent component analysis (ICA) approach has recently been developed for process monitoring, where the goal is to find the independent components (ICs) that are assumed to be non‐Gaussian and mutually independent by means of maximizing the high‐order statistics such as negentropy instead of the second‐order statistics including variance and covariance. Nevertheless, the IC directions do not take into account the contributions from quality variables and, thus, ICA may not work well for process monitoring in the situations when the quality variables have strong influence on process operations. To capture the non‐Gaussian relationships between process measurement and quality variables, a novel projection‐based monitoring method termed as quality relevant non‐Gaussian latent subspace projection (QNGLSP) approach is proposed in this article. This new technique searches for the feature directions within the measurement‐variable and quality‐variable spaces concurrently so that the two sets of feature directions or subspaces have the maximized multidimensional mutual information. Further, the new monitoring indices including I2 and SPE statistics are developed for quality relevant fault detection of non‐Gaussian processes. The proposed QNGLSP approach is applied to the Tennessee Eastman Chemical process and the process monitoring results of the present method are demonstrated to be superior to those of the PLS‐based monitoring method. © 2013 American Institute of Chemical Engineers AIChE J 60: 485–499, 2014
      PubDate: 2013-10-28T10:17:18.148152-05:
      DOI: 10.1002/aic.14261
       
  • Minimization of the nonrenewable energy consumption in bioethanol
           
    • Authors: Robert Brunet; Gonzalo Guillén‐Gosálbez, Laureano Jiménez
      Pages: 500 - 506
      Abstract: The multiobjective optimization of a corn‐based bioethanol plant coupled with a solar‐assisted steam generation system with heat storage is described. Our approach relies on the combined use of process simulation, rigorous optimization tools, and economic and energetic plant analysis. The design task is posed as a bicriteria nonlinear programming problem that considers the simultaneous optimization of the plant profitability and the energy consumption. The capabilities of the proposed methodology are illustrated through a 120,000,000 kg/year corn‐based bioethanol plant considering weather data of Tarragona (Spain). © 2013 American Institute of Chemical Engineers AIChE J 60: 500–506, 2014
      PubDate: 2013-10-28T10:47:03.038351-05:
      DOI: 10.1002/aic.14267
       
  • Economic model predictive control with time‐varying objective
           function for nonlinear process systems
    • Authors: Matthew Ellis; Panagiotis D. Christofides
      Pages: 507 - 519
      Abstract: Economic model predictive control (EMPC) is a control scheme that combines real‐time dynamic economic process optimization with the feedback properties of model predictive control (MPC) by replacing the quadratic cost function with a general economic cost function. Almost all the recent work on EMPC involves cost functions that are time invariant (do not explicitly account for time‐varying process economics). In the present work, we focus on the development of a Lyapunov‐based EMPC (LEMPC) scheme that is formulated with an explicitly time‐varying economic cost function. First, the formulation of the proposed two‐mode LEMPC is given. Second, closed‐loop stability is proven through a theoretical treatment. Last, we demonstrate through extensive closed‐loop simulations of a chemical process that the proposed LEMPC can achieve stability with time‐varying economic cost as well as improve economic performance of the process over a conventional MPC scheme. © 2013 American Institute of Chemical Engineers AIChE J 60: 507–519, 2014
      PubDate: 2013-11-08T02:51:34.621143-05:
      DOI: 10.1002/aic.14274
       
  • Optimal design of split partial second pass reverse osmosis network for
           desalination applications
    • Authors: Yousef Saif; Ali Almansoori, Ali Elkamel
      Pages: 520 - 532
      Abstract: Reverse osmosis (RO) network design problem is presented in this study for seawater desalination. The RO pressure vessel is multiple spiral wound modules connected in series. We exploit in this study the RO pressure vessel operation by considering stream property variations within the pressure vessel itself. The design problem allows extraction of high‐quality permeates from different locations along the pressure vessel length. Superstructure optimization is adopted to model the RO network in order to find: (1) optimal arrangement of the process units, (2) optimal permeate extraction locations, and (3) production of several permeate streams with different qualities. Several case studies are presented to show the applications of the proposed mathematical programming model. In general, lower treatment cost and higher permeate recovery can be achieved by allowing permeate extraction streams from the RO pressure vessels. © 2013 American Institute of Chemical Engineers AIChE J 60: 520–532, 2014
      PubDate: 2013-11-08T02:53:28.563501-05:
      DOI: 10.1002/aic.14271
       
  • Mixture semisupervised principal component regression model and soft
           sensor application
    • Authors: Zhiqiang Ge; Biao Huang, Zhihuan Song
      Pages: 533 - 545
      Abstract: Traditionally, data‐based soft sensors are constructed upon the labeled historical dataset which contains equal numbers of input and output data samples. While it is easy to obtain input variables such as temperature, pressure, and flow rate in the chemical process, the output variables, which correspond to quality/key property variables, are much more difficult to obtain. Therefore, we may only have a small number of output data samples, and have much more input data samples. In this article, a mixture form of the semisupervised probabilistic principal component regression model is proposed for soft sensor application, which can efficiently incorporate the unlabeled data information from different operation modes. Compared to the total supervised method, both modeling efficiency and soft sensing performance are improved with the inclusion of additional unlabeled data samples. Two case studies are provided to evaluate the feasibility and efficiency of the new method. © 2013 American Institute of Chemical Engineers AIChE J 60: 533–545, 2014
      PubDate: 2013-11-09T23:52:32.786628-05:
      DOI: 10.1002/aic.14270
       
  • Modeling and validation of the iodine‐sulfur hydrogen production
           process
    • Authors: Hanfei Guo; Ping Zhang, Songzhe Chen, Laijun Wang, Jingming Xu
      Pages: 546 - 558
      Abstract: The iodine‐sulfur thermochemical water‐splitting cycle (I‐S process) is one of the highly efficient, CO2‐free, massive hydrogen production methods. We simulated the I‐S process through commercial software programs Aspen Plus and OLI database with the aid of self‐developed models to analyze the overall running status of the process and to decrease the investment and time consumption of experiments. A two‐phase separator model operating at 353 K and an electro‐electrodialysis (EED) cell model working at 338 K were built on the basis of experimental data. The entire flow sheet of the I‐S process was modeled based on the two self‐developed models. The simulation models were validated through the experimental results obtained from the closed cycle I‐S facility (IS‐10) in our laboratory. By employing the simulation program, sensitivity analyses of the important parameters in the process were carried out, including the ratio of the distillate to the feed rate of the H2SO4 distillation column, reflux ratio of the H2SO4 column, H2SO4 conversion ratio, HI molality in the EED cathode outlet stream, and HI mole fraction in the liquid and vapor distillates of the HI distillation column. The key parameters significantly affecting the input duty were determined; that is, the ratio of the distillate to the feed rate of the H2SO4 distillation column and the HI molality in the EED cathode outlet stream. The optimal values of the analyzed parameters were also discussed. The simulation program we developed is a useful tool that can evaluate and optimize the I‐S process. © 2013 American Institute of Chemical Engineers AIChE J 60: 546–558, 2014
      PubDate: 2013-11-16T00:39:50.222661-05:
      DOI: 10.1002/aic.14285
       
  • Concurrent phase partition and between‐mode statistical analysis for
           multimode and multiphase batch process monitoring
    • Authors: Chunhui Zhao
      Pages: 559 - 573
      Abstract: The exiting automatic phase partition and phase‐based process monitoring strategies are in general limited to single‐mode multiphase batch processes. In this article, a concurrent phase partition and between‐mode statistical modeling strategy (CPPBM) is proposed for online monitoring of multimode multiphase batch processes. First, the time‐varying characteristics of batch processes are concurrently analyzed across modes so that multiple sequential phases are simultaneously identified for all modes. The feature is that both time‐wise dynamics and mode‐wise variations are considered to get the consistent phase boundaries. Then within each phase, between‐mode statistical analysis is performed where one mode is chosen for the development of reference monitoring system and the relative changes from the reference mode to each alternative mode are analyzed. From the between‐mode perspective, each of the original reference monitoring subspaces, including systematic subspace and residual subspace, are further decomposed into two monitoring subspaces for each alternative mode, which reveal two kinds of between‐mode relative variations. The part which shows significant increases represents the variations that will cause alarm signals if the reference models are used to monitor the alternative modes, whereas the part that shows no increases will not issue alarms. By modeling and monitoring different types of between‐mode relative variations, the proposed CPPBM method can not only efficiently detect faults but also offer enhanced process understanding. It is illustrated with a typical multiphase batch process with multiple modes. © 2013 American Institute of Chemical Engineers AIChE J 60: 559–573, 2014
      PubDate: 2013-11-16T00:35:55.110924-05:
      DOI: 10.1002/aic.14282
       
  • Online prediction of subcutaneous glucose concentration for type 1
           diabetes using empirical models and frequency‐band separation
    • Authors: Chunhui Zhao; Eyal Dassau, Howard C. Zisser, Lois Jovanovič, Francis J. Doyle, Dale E. Seborg
      Pages: 574 - 584
      Abstract: Online glucose prediction which can be used to provide important information of future glucose status is a key step to facilitate proactive management before glucose reaches undesirable concentrations. Based on frequency‐band separation (FS) and empirical modeling approaches, this article considers several important aspects of on‐line glucose prediction for subjects with type 1 diabetes mellitus. Three issues are of particular interest: (1) Can a global (or universal) model be developed from glucose data for a single subject and then used to make suitably accurate on‐line glucose predictions for other subjects? (2) Does a new FS approach based on data filtering provide more accurate models than standard modeling methods? (3) Does a new latent variable modeling method result in more accurate models than standard modeling methods? These and related issues are investigated by developing autoregressive models and autoregressive models with exogenous inputs based on clinical data for two groups of subjects. The alternative modeling approaches are evaluated with respect to on‐line short‐term prediction accuracy for prediction horizons of 30 and 60 min, using independent test data. © 2013 American Institute of Chemical Engineers AIChE J 60: 574–584, 2014
      PubDate: 2013-11-18T11:20:44.170943-05:
      DOI: 10.1002/aic.14288
       
  • Dynamic pH model for autotrophic growth of microalgae in photobioreactor:
           A tool for monitoring and control purposes
    • Authors: George A. Ifrim; Mariana Titica, Guillaume Cogne, Lionel Boillereaux, Jack Legrand, Sergiu Caraman
      Pages: 585 - 599
      Abstract: A dynamic model for the photoautotrophic growth of microalgae in photobioreactor that describes the main variables of the system and allows the precise prediction of the pH in the culture was proposed and validated. The dynamic behavior of the biological system was expressed through a multistate model in continuous‐time formulation, based on mass‐balance equations and local photosynthetic responses of the anisotropic medium, further associated with a set of algebraic equations that describes the thermodynamic properties of the ammonia—carbon dioxide—water ternary solute system. The global photoautotrophic growth model was validated on experimental data acquired from a torus reactor inoculated with Chlamydomonas reinhardtii cells. The model response was studied in simulation for all identified input variables (dilution rate, incident light intensity, temperature, and flow rates of input gases). © 2013 American Institute of Chemical Engineers AIChE J 60: 585–599, 2014
      PubDate: 2013-11-29T00:03:38.95129-05:0
      DOI: 10.1002/aic.14290
       
  • Application of online support vector regression for soft sensors
    • Authors: Hiromasa Kaneko; Kimito Funatsu
      Pages: 600 - 612
      Abstract: Soft sensors have been widely used in chemical plants to estimate process variables that are difficult to measure online. One of the crucial difficulties of soft sensors is that predictive accuracy drops due to changes in state of chemical plants. Characteristics of adaptive soft sensor models such as moving window models, just‐in‐time models and time difference models were previously discussed. The predictive accuracy of any traditional models decreases when sudden changes in processes occur. Therefore, a new soft sensor method based on online support vector regression (SVR) and the time variable was developed for constructing soft sensor models adaptive to rapid changes of relationships among process variables. A nonlinear SVR model with the time variable is updated with the most recent data. The proposed method was applied to simulation data and real industrial data, and achieved higher predictive accuracy than traditional ones even when time‐varying changes in process characteristics happen. © 2013 American Institute of Chemical Engineers AIChE J 60: 600–612, 2014
      PubDate: 2013-12-19T12:08:07.856071-05:
      DOI: 10.1002/aic.14299
       
  • Hydrogenation of CO2 and CO in a high temperature gradient field between
           catalyst surface and opposite inert cool plate
    • Authors: David Perko; Andrej Pohar, Janez Levec
      Pages: 613 - 622
      Abstract: Methanol synthesis was carried out at 25 bar in slit formed by two parallel plates 5 mm apart. Upper plate was covered by catalyst layer and heated up to 250°C, whereas lower one was kept at about 30°C. Reaction stream in laminar flow consisted of H2, CO2, and CO in concentration range usually encountered in industrial processes. Catalyst layer was prepared by spraying CuO/ZnO/Al2O3/V2O3 slurry on SS‐plate. Continuous removal of methanol and water by condensation on the cool surface shifted equilibrium toward products formation. At isothermal conditions with no temperature gradient in slit, total carbon conversion approached the thermodynamic equilibrium when residence time was long enough. Experiments with high temperature difference showed total carbon conversion much larger compared to the thermodynamic one calculated at plate‐catalyst temperature. Three‐dimensional model predicted total carbon conversion for both isothermal and high temperature gradient operation reasonably well. © 2013 American Institute of Chemical Engineers AIChE J 60: 613–622, 2014
      PubDate: 2013-11-15T18:50:19.026291-05:
      DOI: 10.1002/aic.14280
       
  • Revisiting the steady states of NO/O2/C3H6 on monolithic Pt/BaO/Al2O3
           using bifurcation analysis
    • Authors: Wei Xu; Meng‐Long Lai, Wei‐Fang Yu, Jin Xu
      Pages: 623 - 634
      Abstract: While NOx storage and reduction is periodically operated, steady‐state studies have been widely carried out to investigate the involved reaction mechanisms and effects of operating parameters. Due to the complex reaction chemistry and its coupling with transport phenomena, multiplicity may exist. A steady‐state monolith reactor model accounting for microkinetics and reaction heat effects was proposed in this study to avoid the evaluation of enthalpies of microreaction steps. Three simplified versions of the monolith model were developed based on various assumptions of the axial gradients. Steady‐state behaviors of NO/O2/C3H6 system were investigated. A predictor‐corrector (PC) continuation method that does not require explicit evaluation of Jacobian Matrix was developed to solve the nonlinear system with a variable parameter of feed temperature. Model predictions were compared with experimental results. © 2013 American Institute of Chemical Engineers AIChE J 60: 623–634, 2014
      PubDate: 2013-11-16T00:03:44.015171-05:
      DOI: 10.1002/aic.14263
       
  • Steam reforming of ethanol over skeletal Ni‐based catalysts: A
           temperature programmed desorption and kinetic study
    • Authors: Chengxi Zhang; Shuirong Li, Gaowei Wu, Zhiqi Huang, Zhiping Han, Tuo Wang, Jinlong Gong
      Pages: 635 - 644
      Abstract: An investigation on reaction scheme and kinetics for ethanol steam reforming on skeletal nickel catalysts is described. Catalytic activity of skeletal nickel catalyst for low‐temperature steam reforming has been studied in detail, and the reasons for its high reactivity for H2 production are attained by probe reactions. Higher activity of water gas shift reaction and methanation contributes to the low CO selectivity. Cu and Pt addition can promote WGSR and suppress methanation, and, thus, improve H2 production. A reaction scheme on skeletal nickel catalyst has been proposed through temperature programmed reaction spectroscopy experiments. An Eley‐Rideal model is put forward for kinetic studies, which contains three surface reactions: ethanol decomposition, water gas shift reaction, and methane steam reforming reaction. The kinetics was studied at 300–400°C using a randomized algorithms method and a least‐squares method to solve the differential equations and fit the experimental data; the goodness of fit obtained with this model is above 0.95. The activation energies for the ethanol decomposition, methane steam reforming, and water gas shift reaction are 187.7 kJ/mol, 138.5 kJ/mol and 52.8 kJ/mol, respectively. Thus, ethanol decomposition was determined to be the rate determining reaction of ethanol steam reforming on skeletal nickel catalysts. © 2013 American Institute of Chemical Engineers AIChE J 60: 635–644, 2014
      PubDate: 2013-11-20T17:19:23.490923-05:
      DOI: 10.1002/aic.14264
       
  • Production and examination of oxygen‐carrier materials based on
           manganese ores and Ca(OH)2 in chemical looping with oxygen uncoupling
    • Authors: Nasim M. Pour; Golnar Azimi, Henrik Leion, Magnus Rydén, Anders Lyngfelt
      Pages: 645 - 656
      Abstract: This study concerns production of oxygen‐carrier particles using six different manganese ores. The ores were made to react with Ca(OH)2 at elevated temperature, forming calcium manganite. The method utilized to manufacture particles was extrusion. Methane and syngas conversion and oxygen release of the samples in inert atmosphere were investigated. The oxygen carrier based on South African (B) manganese ore, showed good methane conversion and was able to transfer oxygen corresponding to 1.5% of its mass during reduction with gaseous fuel. All examined oxygen carriers were capable of converting syngas completely. The ability to release gaseous oxygen was examined by adding wood char in a stream of nitrogen for four selected samples sintered at 1300°C/6 h. These samples released an amount of oxygen corresponding to 0.37–0.68% of their mass. The reactivity of all the ores was improved after the proposed treatments. Reactivity results of the oxygen carrier made from South African (B) ore and Ca(OH)2, sintered at 1300°C for 6 h were the most promising. Attrition measurements with a jet cup of the oxygen carriers sintered at 1300°C/6 h showed that all the samples made from ores were at least three times more resistant to mechanical attrition compared to particles made from synthetic Mn2O3. Producing feasible oxygen carriers directly from ores could potentially cut the cost of chemical looping with oxygen uncoupling and have a significant impact on its competitiveness among other carbon capture technologies. © 2013 American Institute of Chemical Engineers AIChE J 60: 645–656, 2014
      PubDate: 2013-11-09T23:36:46.498753-05:
      DOI: 10.1002/aic.14273
       
  • Comprehensive modeling and CFD simulation of absorption of CO2 and H2S by
           MEA solution in hollow fiber membrane reactors
    • Authors: Seyyed Mohammad Hossein Hashemi Amrei; Saber Memardoost, Asghar Molaei Dehkordi
      Pages: 657 - 672
      Abstract: A comprehensive mathematical model has been developed for the simulation of simultaneous chemical absorption of carbon dioxide and hydrogen sulfide by means of Monoethanolamine (MEA) aqueous solution in hollow fiber membrane reactors is described. In this regard, a perfect model considering the entrance regions of momentum, energy, and mass transfers was developed. Computational Fluid Dynamics (CFD) techniques were applied to solve governing equations, and the model predictions were validated against experimental data reported in the literature and excellent agreement was found. Effects of different disturbances on the dynamic behavior of the reactor were investigated. Moreover, effects of various parameters such as wetting fraction, gas and liquid inlet velocities, inlet temperature of the solvent, MEA concentration, and CO2 and H2S compositions were carefully studied. It was found that for large values of gas velocity or small values of liquid velocity, the thermal energy equation can play an important role in the model predictions. © 2013 American Institute of Chemical Engineers AIChE J 60: 657–672, 2014
      PubDate: 2013-11-18T11:48:34.779948-05:
      DOI: 10.1002/aic.14286
       
  • The role of water on postcombustion CO2 capture by vacuum swing
           adsorption: Bed layering and purge to feed ratio
    • Authors: Gang Li; Penny Xiao, Jun Zhang, Paul A. Webley, Dong Xu
      Pages: 673 - 689
      Abstract: The influence of water vapor on the adsorption of CO2 in carbon capture by vacuum swing adsorption (VSA) was described. VSA experiments with single and multilayered columns using alumina and zeolite 13X were conducted to understand the migration of water. The penetration depth of water in the column could be controlled by maintaining the purge‐to‐feed ratio above a critical value. At high water content in the feed (>4%), employment of a water adsorbing prelayer was essential to prevent failure of the carbon capture process. A simple axial working capacity model predicts the penetration depth of water in the column for a given feed temperature and adsorption isotherm, and the layering ratio can be selected accordingly. Although water is detrimental to CO2 capture with polar adsorbents, long‐term recovery of CO2 is still possible by appropriate layering and ensuring an adequate purge‐to‐feed ratio. © 2013 American Institute of Chemical Engineers AIChE J 60: 673–689, 2014
      PubDate: 2013-11-21T16:55:54.646437-05:
      DOI: 10.1002/aic.14281
       
  • Investigation of flow parameters and efficiency of mixture separation on a
           structured packing
    • Authors: Аleksandr Pavlenko; Vladimir Zhukov, Nikolay Pecherkin, Vladimir Chekhovich, Oleg Volodin, Alexey Shilkin, Christoph Grossmann
      Pages: 690 - 705
      Abstract: Results of experimental study of the effect of initial maldistribution of structured packing irrigation on efficiency of binary mixture separation are presented in this article. The studies were carried out in the experimental distillation column with the diameter of 0.9 m using the R114 and R21 freon mixture. Experiments were performed on the structured Mellapak 350.Y packing of stainless steel 316L, containing 19 layers with the total height of 4.016 m at the ratio of mole liquid and vapor flow rates L/V = 1 and 1.7, respectively, and the pressure in the upper part of the column ptop = 3 bars. Nonuniformity at the packing inlet was generated via the blocking of some holes in the liquid distributor. Here, we present some results on efficiency of mixture separation, pressure drop on the packing, distribution of local liquid flow rate under the packing over the cross‐section and on the column wall within the range of vapor loading factor (0.69 
      PubDate: 2013-12-05T10:50:52.336102-05:
      DOI: 10.1002/aic.14298
       
  • UNIFAC model for ionic liquid‐CO2 systems
    • Authors: Zhigang Lei; Chengna Dai, Wei Wang, Biaohua Chen
      Pages: 716 - 729
      Abstract: The new group binary interaction parameters of UNIFAC model (anm and amn) between CO2 and 22 ionic liquid (IL) groups were obtained by means of correlating the solubility data of CO2 in pure ILs at different temperatures (>273.2 K). We measured the CO2 solubility at low temperatures down to 243.2 K in pure ILs, i.e., [OMIM]+[BF4]− and [OMIM]+[Tf2N]−, and their equimolar amount of mixture, in order to fill the blank of solubility data at low temperatures and also to justify the applicability of UNIFAC model over a wider temperature range. It was verified that UNIFAC model can be used for predicting the CO2 solubility in pure ILs and in the binary mixture of ILs both at high (>273.2 K) and low temperatures (
      PubDate: 2013-11-26T10:30:27.893242-05:
      DOI: 10.1002/aic.14294
       
  • Bubble point pressures of binary methanol/water mixtures in
           fine‐mesh screens
    • Authors: Jason Hartwig; J. Adin Mann
      Pages: 730 - 739
      Abstract: Binary methanol/water mixture bubble point tests involving three samples of fine‐mesh, stainless steel screens as porous liquid acquisition devices are presented in this article. Contact angles are measured as a function of methanol mass fraction using the Sessile Drop technique. Pretest predictions are based on a Langmuir isotherm fit. Predictions and data match for methanol mole fractions greater than 50% when pore diameters are based on pure liquid tests. For all three screens, bubble point is shown to be a maximum at a methanol mole fraction of 50%. Model and data are in disagreement for mole fractions less than 50%, which is attributed to variations between surface and bulk fluid properties. A critical Zisman surface tension value of 23.2 mN/m is estimated, below which contact angles can be assumed to be zero. Solid/vapor and solid/liquid interfacial tensions are also estimated using the equation of state analysis from Neumann and Good. Published 2013 American Institute of Chemical Engineers AIChE J 60: 730–739, 2014
      PubDate: 2013-12-19T11:09:09.571253-05:
      DOI: 10.1002/aic.14293
       
  • Multiphase hydrodynamics and distribution characteristics in a monolith
           bed measured by optical fiber probe
    • Authors: Yuan Zhou; Milorad P. Dudukovic, Muthanna H. Al‐Dahhan, Hui Liu
      Pages: 740 - 748
      Abstract: The optical fiber probe has been for the first time applied to investigate the hydrodynamics and gas‐phase distribution at high gas/liquid ratios in a two‐phase flow monolith bed with 0.048 m diameter and 400 cpsi. Local hydrodynamic parameters including gas holdup, bubble frequency, bubble velocity, and bubble length in single channels were measured by 16 inserted single‐point optical fiber probes within the bed under a nozzle as the liquid distributor. The following findings are reported. (1) The optical fiber probe can be used as an efficient and convenient technique for measuring local hydrodynamic parameters inside the channels of a monolith bed; (2) within the range of high gas/liquid ratios under which experiments were conducted, churn flow regime occurred. In this regime, the monolith bed radial distribution of gas holdup, bubble frequency, bubble velocity, and bubble length is nonuniform in nature. © 2013 American Institute of Chemical Engineers AIChE J 60: 740–748, 2014
      PubDate: 2013-10-30T10:49:37.592221-05:
      DOI: 10.1002/aic.14269
       
  • Numerical derivation of dispersion coefficients for flow through
           three‐dimensional randomly packed beds of monodisperse spheres
    • Authors: Amir Jourak; J. Gunnar I. Hellström, T. Staffan Lundström, Vilnis Frishfelds
      Pages: 749 - 761
      Abstract: The longitudinal (DL) and transverse (DT) dispersion coefficients for flow through randomly packed beds of discrete monosized spherical particles are studied. The three‐dimensional (3‐D) porous‐medium model consists of thousands of spherical particles that are divided into cells using Voronoi diagrams. The relationship between the variation of the dual stream function and the vorticity between neighboring particles is derived using Laurent series. The whole flow pattern at low particle Reynolds number is then obtained by minimization of the dissipation rate of energy with respect to the dual stream function. The DL is obtained by fitting the resulting effluent curve to a 1‐D solution of a continuous model. The DT is obtained by fitting the numerical concentration profile to an approximate 2‐D solution. The derived DL and DT values are in agreement with 3‐D experimental data from the literature enabling a study of the effects of pore structure and porosity on DL and DT. © 2013 American Institute of Chemical Engineers AIChE J 60: 749–761, 2014
      PubDate: 2013-11-15T10:38:07.908839-05:
      DOI: 10.1002/aic.14284
       
  • Analysis of superheated loop heat pipes exploiting nanoporous wick
           membranes
    • Authors: I‐Tzu Chen; Amit Pharkya, Abraham D. Stroock
      Pages: 762 - 777
      Abstract: The design and analysis of plant‐inspired loop heat pipes (LHPs) that would exploit nanoporous membranes to allow for operation with large capillary pressures and superheated liquid are presented. The operating concepts of this superheated loop heat pipe (SHLHP) resemble the transpiration process in vascular plants: reduction of pressure in leaves drives sap flow up from the roots and overcomes gravity, viscous drag, and reduced chemical potential of water in subsaturated soils. We present a model for steady‐state operation and a linear response analysis of both the conventional and superheated designs. Our analysis shows that these SHLHPs could: (1) extend the limitations of conventional LHPs imposed by thermodynamic properties of the working fluid, (2) provide efficient heat transfer over long distances and against large accelerations, and (3) allow for operation in a subsaturated state that would eliminate the thermal resistance and entrainment effect of the liquid film of conventional designs. © 2013 American Institute of Chemical Engineers AIChE J 60: 762–777, 2014
      PubDate: 2013-12-17T11:04:25.872978-05:
      DOI: 10.1002/aic.14303
       
 
 
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