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  Subjects -> ENGINEERING (Total: 2070 journals)
    - CHEMICAL ENGINEERING (171 journals)
    - CIVIL ENGINEERING (161 journals)
    - ELECTRICAL ENGINEERING (88 journals)
    - ENGINEERING (1148 journals)
    - ENGINEERING MECHANICS AND MATERIALS (320 journals)
    - HYDRAULIC ENGINEERING (52 journals)
    - INDUSTRIAL ENGINEERING (52 journals)
    - MECHANICAL ENGINEERING (78 journals)

ENGINEERING (1148 journals)            First | 1 2 3 4 5 6 7 8 | Last

Bharatiya Vaigyanik evam Audyogik Anusandhan Patrika (BVAAP)     Open Access  
Biointerphases     Open Access  
Biomaterials Science     Full-text available via subscription   (Followers: 4)
Biomedical Engineering     Hybrid Journal   (Followers: 10)
Biomedical Engineering and Computational Biology     Open Access   (Followers: 13)
Biomedical Engineering Letters     Hybrid Journal   (Followers: 5)
Biomedical Engineering, IEEE Reviews in     Full-text available via subscription   (Followers: 16)
Biomedical Engineering, IEEE Transactions on     Hybrid Journal   (Followers: 14)
Biomedical Engineering: Applications, Basis and Communications     Hybrid Journal   (Followers: 5)
Biomedical Microdevices     Hybrid Journal   (Followers: 7)
Biomedical Science and Engineering     Open Access   (Followers: 1)
Biomedizinische Technik - Biomedical Engineering     Full-text available via subscription  
Biomicrofluidics     Open Access   (Followers: 2)
BioNanoMaterials     Full-text available via subscription   (Followers: 1)
Biotechnology Progress     Hybrid Journal   (Followers: 21)
Boletin Cientifico Tecnico INIMET     Open Access  
Botswana Journal of Technology     Full-text available via subscription  
Boundary Value Problems     Open Access   (Followers: 1)
Brazilian Journal of Science and Technology     Open Access  
Broadcasting, IEEE Transactions on     Hybrid Journal   (Followers: 5)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 1)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 3)
Bulletin of the Crimean Astrophysical Observatory     Hybrid Journal  
Calphad     Hybrid Journal  
Canadian Geotechnical Journal     Full-text available via subscription   (Followers: 15)
Canadian Journal of Remote Sensing     Full-text available via subscription   (Followers: 13)
Case Studies in Engineering Failure Analysis     Open Access   (Followers: 4)
Case Studies in Thermal Engineering     Open Access   (Followers: 1)
Catalysis Communications     Hybrid Journal   (Followers: 4)
Catalysis Letters     Hybrid Journal   (Followers: 1)
Catalysis Reviews: Science and Engineering     Hybrid Journal   (Followers: 6)
Catalysis Science and Technology     Free   (Followers: 4)
Catalysis Surveys from Asia     Hybrid Journal   (Followers: 4)
Catalysis Today     Hybrid Journal   (Followers: 6)
CEAS Space Journal     Hybrid Journal   (Followers: 1)
Cellular and Molecular Neurobiology     Hybrid Journal   (Followers: 2)
Central European Journal of Engineering     Hybrid Journal   (Followers: 1)
CFD Letters     Open Access   (Followers: 2)
Chaos : An Interdisciplinary Journal of Nonlinear Science     Hybrid Journal   (Followers: 1)
Chaos, Solitons & Fractals     Hybrid Journal   (Followers: 1)
Chinese Journal of Catalysis     Full-text available via subscription   (Followers: 1)
Chinese Journal of Engineering     Open Access  
Chinese Science Bulletin     Open Access  
Ciencia e Ingenieria Neogranadina     Open Access  
Ciencia en su PC     Open Access  
Ciencias Holguin     Open Access  
Cientifica     Open Access  
CIRP Annals - Manufacturing Technology     Full-text available via subscription   (Followers: 10)
CIRP Journal of Manufacturing Science and Technology     Full-text available via subscription   (Followers: 8)
City, Culture and Society     Hybrid Journal   (Followers: 20)
Clay Minerals     Full-text available via subscription   (Followers: 11)
Clean Air Journal     Full-text available via subscription   (Followers: 2)
Clinical Science     Full-text available via subscription   (Followers: 5)
Coal Science and Technology     Full-text available via subscription   (Followers: 3)
Coastal Engineering     Hybrid Journal   (Followers: 8)
Coastal Engineering Journal     Hybrid Journal   (Followers: 1)
Coatings     Open Access   (Followers: 2)
Cogent Engineering     Open Access   (Followers: 1)
Cognitive Computation     Hybrid Journal   (Followers: 3)
Color Research & Application     Hybrid Journal   (Followers: 1)
COMBINATORICA     Hybrid Journal  
Combustion Theory and Modelling     Hybrid Journal   (Followers: 5)
Combustion, Explosion, and Shock Waves     Hybrid Journal   (Followers: 10)
Communications Engineer     Hybrid Journal  
Communications in Information Science and Management Engineering     Open Access   (Followers: 7)
Communications in Numerical Methods in Engineering     Hybrid Journal   (Followers: 3)
Components, Packaging and Manufacturing Technology, IEEE Transactions on     Hybrid Journal   (Followers: 12)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Composite Structures     Hybrid Journal   (Followers: 72)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 53)
Composites Part B : Engineering     Hybrid Journal   (Followers: 72)
Composites Science and Technology     Hybrid Journal   (Followers: 54)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 11)
Computational Optimization and Applications     Hybrid Journal   (Followers: 6)
Computational Science and Discovery     Full-text available via subscription  
Computational Water, Energy, and Environmental Engineering     Open Access   (Followers: 2)
Computer Applications in Engineering Education     Hybrid Journal   (Followers: 7)
Computer Science and Engineering     Open Access   (Followers: 8)
Computers & Geosciences     Hybrid Journal   (Followers: 6)
Computers & Mathematics with Applications     Full-text available via subscription   (Followers: 4)
Computers and Electronics in Agriculture     Hybrid Journal   (Followers: 3)
Computers and Geotechnics     Hybrid Journal   (Followers: 6)
Computing and Visualization in Science     Hybrid Journal   (Followers: 3)
Computing in Science & Engineering     Full-text available via subscription   (Followers: 13)
Conciencia Tecnologica     Open Access   (Followers: 1)
Concurrent Engineering     Hybrid Journal   (Followers: 3)
Conference Proceedings - Lucian Blaga University Sibiu     Open Access  
Continuum Mechanics and Thermodynamics     Hybrid Journal   (Followers: 3)
Control and Dynamic Systems     Full-text available via subscription   (Followers: 4)
Control Engineering Practice     Hybrid Journal   (Followers: 22)
Control Theory and Informatics     Open Access   (Followers: 4)
Corrosion Science     Hybrid Journal   (Followers: 21)
Corrosion Series     Full-text available via subscription   (Followers: 7)
CT&F Ciencia, Tecnologia y Futuro     Open Access  
Current Applied Physics     Full-text available via subscription   (Followers: 4)
Dams and Reservoirs     Hybrid Journal   (Followers: 3)
Data Handling in Science and Technology     Full-text available via subscription   (Followers: 2)

  First | 1 2 3 4 5 6 7 8 | Last

Journal Cover   AIChE Journal
  [SJR: 0.889]   [H-I: 94]   [22 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  [1606 journals]
  • Adaptive model predictive inventory controller for multiproduct batch
           plant
    • Authors: Gyeongbeom Yi; Gintaras V. Reklaitis
      Pages: n/a - n/a
      Abstract: An inventory control system was developed for multiproduct batch plants with an arbitrary number of batch processes and storage units. Customer orders are received by the plant at order intervals and in order quantities that are subject to random fluctuations. The objective of the plant operation is to minimize the total cost while maintaining inventory levels within the storage or warehouse capacity by adjusting the startup times, the quantities of raw material orders, and production batch sizes. An adaptive model predictive control algorithm was developed that uses a periodic square wave model to represent the flows of the material between the processes and the storage units. The boundedness of the control output and the convergence of the estimated parameters in implementations of the proposed algorithm were mathematically proven under the assumption that disturbances in the orders are bounded. The effectiveness of this approach was demonstrated by performing simulations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-28T03:39:12.715973-05:
      DOI: 10.1002/aic.14783
       
  • Model‐based analysis of a gas/vapor‐liquid micro‐channel
           membrane contactor
    • Authors: A. Lautenschleger; A. Voigt, K. Sundmacher, E. Y. Kenig
      Pages: n/a - n/a
      Abstract: A comprehensive numerical investigation on membrane distillation of methanol and water in a micro‐separator was carried out. The focus was to investigate the impact of the apparatus geometry on the separation performance and to develop alternative designs for process intensification. To describe the process, a CFD‐based model was developed and validated against experimental data from literature. Based on this model, parametric studies were performed to gain a deeper understanding of the microchannel geometry influence. Furthermore, two geometry modifications were suggested and analysed, a miniaturisation of the channel and an implementation of baffles. The modification with baffles was chosen for a new separator design which was studied experimentally, and the obtained experimental data were used for another model validation, this time for the baffle arrangement. A subsequent comprehensive simulations were performed to investigate mass transfer enhancement by the modified geometry. Generally, the baffles revealed a considerable potential for the process intensification. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-28T02:56:45.277685-05:
      DOI: 10.1002/aic.14784
       
  • Design and screening of ionic liquids for C2H2/C2H4 separation by
           COSMO‐RS and experiments
    • Authors: Xu Zhao; Qiwei Yang, Dan Xu, Zongbi Bao, Yi Zhang, Baogen Su, Qilong Ren, Huabin Xing
      Pages: n/a - n/a
      Abstract: Ionic liquids (ILs) have been proposed as promising solvents for separating C2H2 and C2H4, but screening an industrially attractive IL with high capacity from numerous available ILs remains challenging. In this work, a rapid screening method based on COSMO‐RS was developed. We also present an efficient strategy to improve the C2H2 capacity in ILs together with adequate C2H2/C2H4 selectivity with the aid of COSMO‐RS. The essence of this strategy is to increase molecular free volume of ILs and simultaneously enhance hydrogen‐bond basicity of anions by introducing flexible and highly asymmetric structures, which is validated by a new class of tetraalkylphosphonium ILs featuring long‐chain carboxylate anions. At 298.1K and 1 bar, the solubility of C2H2 in ILs reaches 0.476 mole per mole IL, very high for a physical absorption, with a selectivity of up to 21.4. The separation performance of tetraalkylphosphonium ILs to the mixture of C2H2/C2H4 was also evaluated. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-27T01:51:20.509619-05:
      DOI: 10.1002/aic.14782
       
  • Shear‐rate‐dependent rheology effects on mass transport and
           surface reactions in biomicrofluidic devices
    • Authors: Arman Sadeghi; Younes Amini, Mohammad Hassan Saidi, Hadi Yavari
      Pages: n/a - n/a
      Abstract: Consideration is given to shear‐rate‐dependent rheology effects on mass transport in a heterogeneous microreactor of rectangular cross section, utilizing both numerical and analytical approaches. The carrier liquid obeys the power‐law viscosity model and is actuated primarily by an electrokinetic pumping mechanism. It is discovered that, considering the shear‐thinning biofluids to be Newtonian fluids gives rise to an overestimation of the saturation time. The degree of overestimation is higher in the presence of large Damkohler numbers and EDL thicknesses. It is also increased by the application of a favorable pressure gradient, whereas the opposite is true when an opposed pressure gradient is applied. In addition, a channel of square cross section corresponds to the maximum fluid rheology effects. Finally, the numerical results indicate the existence of a concentration wave when employing long channels. This is confirmed by analytical solutions, providing a closed form solution for wave propagation speed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-27T01:50:37.000629-05:
      DOI: 10.1002/aic.14781
       
  • Modeling segregation of bidisperse granular materials using physical
           control parameters in the quasi‐2D bounded heap
    • Authors: Conor P. Schlick; Yi Fan, Austin B. Isner, Paul B. Umbanhowar, Julio M. Ottino, Richard M. Lueptow
      Pages: n/a - n/a
      Abstract: Quantitatively predicting segregation of size‐disperse granular materials is of potential value in many industrial applications. We consider granular segregation of size‐bidisperse particles in quasi‐2D bounded heaps, a canonical granular flow, using an advection‐diffusion transport equation with an additional term to account for particle segregation. The equation is characterized by two dimensionless parameters that are functions of control parameters (flow rate, system size, and particle sizes) and kinematic parameters (flowing layer depth, diffusion coefficient, and percolation length scale). As the kinematic parameters are usually difficult to measure in practice, their dependence on the control parameters is determined directly from discrete element method (DEM) simulations. Using these relationships, it is possible to determine which values of the control parameters result in a mixed or segregated heap. The approach used here is broadly applicable to a wide range of other flow geometries and particle systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-25T17:19:35.424837-05:
      DOI: 10.1002/aic.14780
       
  • Evaporation of pinned droplets containing polymer ‐ an examination
           of the important groups controlling final shape
    • Authors: Adam D. Eales; Nick Dartnell, Simon Goddard, Alexander F. Routh
      Pages: n/a - n/a
      Abstract: Controlling the final shape resulting from evaporation of pinned droplets containing polymer, is important in the fabrication of P‐OLED displays by inkjet printing. Typically a coffee‐ring shape arises, due to the pinning and associated outward capillary flow. For operational reasons, this is undesirable ‐ a flat topography is required. We wish to understand the important groups governing the shape, to provide a practical guide to ink selection. The theory presented is based on a thin‐film lubrication model. We solve the governing equations numerically and continuously track the lateral progression of a liquid/gel front. A large capillary number or large ratio of initial to maximal polymer volume fraction can suppress the coffee‐ring. White light interferometry is used to confirm these findings experimentally. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-25T03:43:02.757351-05:
      DOI: 10.1002/aic.14777
       
  • Gas absorption into a wavy two‐layer falling film
    • Authors: G. Çekiç; G. M. Sisoev
      Pages: n/a - n/a
      Abstract: Absorption of a weakly soluble gas into a two‐layer film flowing down a vertical wall is studied in the framework of an approximate long‐wave model. It is shown that wavy regimes in the film strongly affect the absorption rate. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-25T03:42:43.53357-05:0
      DOI: 10.1002/aic.14778
       
  • Anatomy of a rapid pressure swing adsorption (RPSA) process performance
    • Authors: Vemula Rama Rao; Mayuresh V. Kothare, Shivaji Sircar
      Pages: n/a - n/a
      Abstract: A detailed numerical study of the individual and cumulative effects of various mass, heat and momentum transfer resistances, which are generally present inside a practical adiabatic adsorber, on the overall separation performance of a rapid pressure swing adsorption (RPSA) process is carried out for production of nearly pure helium gas from an equi‐molar binary (N2 + He) gas mixture using 5 A zeolite. Column bed size factor (BSF) and helium recovery (R) from the feed gas are used to characterize the separation performances. All practical impediments like column pressure drop, finite gas‐solid mass and heat transfer resistances, mass and heat axial dispersions in the gas phase, and heats of ad(de)sorption causing non‐isothermal operation have detrimental impacts on the overall process performance, which are significantly accentuated when the total cycle time of a RPSA process is small and the product gas helium purity is high. These impediments also prohibit indefinite lowering of BSF (desired performance) by decreasing process cycle time alone. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-24T18:56:33.028039-05:
      DOI: 10.1002/aic.14779
       
  • A CO2‐stable hollow‐fiber membrane with high hydrogen
           permeation flux
    • Authors: Yan Chen; Yanying Wei, Qing Liao, Zhong Li, Armin Feldhoff, Juergen Caro, Haihui Wang
      Pages: n/a - n/a
      Abstract: A Mo‐substituted lanthanum tungstate mixed proton‐electron conductor, La5.5W0.6Mo0.4O11.25‐δ (LWM04), was synthesized using solid state reactions. Dense U‐shaped LWM04 hollow‐fiber membranes were successfully prepared using wet‐spinning phase‐inversion and sintering. The stability of LWM04 in a CO2‐containing atmosphere and the permeation of hydrogen through the LWM04 hollow‐fiber membrane were investigated in detail. A high hydrogen permeation flux of 1.36 ml/min·cm2 was obtained for the U‐shaped LWM04 hollow‐fiber membranes at 975 °C when a mixture of 80% H2‐20% He was used as the feed gas and the sweep side was humidified. Moreover, the hydrogen permeation flux did not significantly decrease over 70 h of operation when fed with a mixture containing 25% CO2, 50% H2, and 25% He, indicating that the LWM04 hollow‐fiber membrane has good stability under a CO2‐containing atmosphere. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-24T06:00:55.500767-05:
      DOI: 10.1002/aic.14772
       
  • Co‐gasification of Blended Coal‐Biomass in an Air/Steam BFB
           Gasifier: Experimental Investigation and Model Validation
    • Authors: Qixiang Xu; Shusheng Pang, Tana Levi
      Pages: n/a - n/a
      Abstract: In this study, a series of co‐gasification experiments were performed at a 100 kW bubbling fluidized bed (BFB) gasifier to gasify the blended pellets made from two types of coals and woody biomass, with biomass‐to‐fuel mass ratios of 0‐30%. In the co‐gasification, a mixture of air and steam was fed from the BFB gasifier bottom as gasification agent and the blended biomass‐coal pellets were fed into the bed layer. Impacts of biomass mass fraction in the binary pellets and gasification operation temperature on producer gas composition were experimentally investigated. The experimental results have been used to validate a mathematical model developed in this study. From both experimental observation and model prediction, it was found that adding biomass into coal has overall negative impact on producer gas quality in terms of combustible substance contents, and the extents of the blending effect were different among fuel types which have different properties. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-24T05:43:48.357452-05:
      DOI: 10.1002/aic.14773
       
  • Template‐free synthesis of single‐/double‐walled TiO2
           nanovesicles: Potential photocatalysts for engineering application
    • Authors: Gongde Chen; He Cheng, Weixin Zhang, Zeheng Yang, Maoqin Qiu, Xiao Zhu, Min Chen
      Pages: n/a - n/a
      Abstract: Single‐ and double‐walled anatase TiO2 nanovesicles have been respectively prepared by a template‐free hydrothermal treatment of Ti(SO4)2 with H2O2 and urea. Photocatalytic degradation of Rhodamine B indicates that double‐walled TiO2 nanovesicles have an initial lower but a final higher photocatalytic efficiency than single‐walled ones. All nanovesicles have significantly lower performance than commercially available P25 TiO2. The enhanced capacity for UV light absorption and •OH radicals production, large specific surface area, and unique hierarchical hollow architectures contributes to the enhanced photocatalytic activity and improved feasibility of anatase TiO2 nanovesicles for engineering applications. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-23T18:47:35.582832-05:
      DOI: 10.1002/aic.14774
       
  • Mathematical modeling of polyethylene terephthalate (PET) pyrolysis in a
           spouted bed
    • Authors: Arezou Niksiar; Amir Hasan Faramarzi, Morteza Sohrabi
      Pages: n/a - n/a
      Abstract: A model has been developed for pyrolysis of PET in a spouted bed reactor based on the conservation equations for heat, mass, and momentum transports. A spouted bed has been constructed and the kinetic parameters have been obtained within the temperature range of 723‐833 K, using two particle size ranges, (0.1‐1.0)×10‐3 and (1.0‐3.0)×10‐3 m. The model’ predictions for the radial distributions of temperature and concentration confirm the excellent mixing of particles. Thus, spouted beds are appropriate equipments for performing kinetic studies of PET pyrolysis. The inlet gas temperature and the mass of PET highly affect PET conversion. The amount of inert particles has a negligible effect on the conversion and it can be reduced as far as a stable spouting is preserved. The gas flow suffices to eliminate the external heat and mass transfer limitations. It can be reduced to the minimum value in order to decrease the energy consumption. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-23T18:47:18.747821-05:
      DOI: 10.1002/aic.14775
       
  • Effects of axial circulation and dispersion geometry on the scale‐up
           of ultrasonic extraction of polysaccharides
    • Authors: Ibrahim Alzorqi; Sivakumar Manickam
      Pages: n/a - n/a
      Abstract: The ultrasonic‐assisted extraction (UAE) of polysaccharides (PS) from Ganoderma lucidum, was subjected to a scale‐up study. 0.25 L extractor was employed to optimize the extraction conditions toward maximum yield of PS. The extracted PS was observed to be reduced by increasing the scale from 1 to 6 L. To intensify the extraction, axial circulation at different stirring rates was induced and optimized in a 3L U‐tube extractor. Although circulation at 300 rpm improved the yield of PS for 3 L, introducing dispersion geometry (conical funnel) and adjusting the radiation distance in a 6 L U‐tube extractor further intensified the extraction efficiency. A radiation distance of 4 cm and circulation induced using 600 rpm enhanced the PS as compared to the conventional 6 L extractor. Overall, the scale‐up from 0.25 to 6 L was successful and introducing circulation and dispersion geometry intensified the extraction efficiency under similar dissipation of ultrasonic power. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-23T18:41:45.975699-05:
      DOI: 10.1002/aic.14776
       
  • “Perspective: AIChE 2014 alpha chi sigma award”
    • Authors: Paula T. Hammond; David H. Koch
      Pages: n/a - n/a
      PubDate: 2015-02-22T23:47:30.419326-05:
      DOI: 10.1002/aic.14770
       
  • Practical improvements to autocovariance least‐squares
    • Authors: Megan A. Zagrobelny; James B. Rawlings
      Pages: n/a - n/a
      Abstract: Identifying disturbance covariances from data is a critical step in estimator design and controller performance monitoring. We examine here the autocovariance least‐squares (ALS) method for this identification. For large industrial models with poorly observable states, the process noise covariance is high dimensional and the optimization problem is poorly conditioned. Also, weighting the least‐squares problem with the identity matrix does not provide minimum variance estimates. Here we modify ALS method to resolve these two challenges. We identify and remove poorly observable states using the SVD of the observability matrix, thus decreasing the computational time. Using a new feasible generalized least‐squares estimator that approximates the optimal weighting from data, we significantly reduce the variance of the estimates. We successfully demonstrate the new approach on industrial data sets provided by Praxair. The disturbance model identified by the ALS method produces an estimator that performs optimally over a year‐long period. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-22T23:46:57.965434-05:
      DOI: 10.1002/aic.14771
       
  • Freeze‐drying of initially unsaturated material frozen with
           pre‐built pores
    • Authors: Wei Wang; Dapeng Hu, Yanqiu Pan, Yanqiang Zhao, Guohua Chen
      Pages: n/a - n/a
      Abstract: In order to save drying time and increase productivity, a novel idea was proposed for freeze‐drying of liquid materials by creating an initially unsaturated frozen structure. An experimental investigation was carried out aiming at verifying the idea using a multifunctional freeze‐drying apparatus. Mannitol was selected as the primary solute in aqueous solution. Liquid nitrogen ice‐cream making method was employed to prepare the frozen materials with different initial porosities. Results show that freeze‐drying can be significantly enhanced with the initially unsaturated frozen material, and substantial drying time can be saved compared with conventional freeze‐drying of the initially saturated one. Drying time was found to decrease with the decrease in the initial saturation. The drying time for the initially unsaturated frozen sample (S0=0.28 or 0.69 of initial porosity) can be at best 32% shorter than that required for the saturated one (S0=1.00 or zero porosity). This unique technique is easy to implement and improves the freeze‐drying performance of liquid materials. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-17T16:06:45.317032-05:
      DOI: 10.1002/aic.14769
       
  • DEM‐CFD modelling of particle systems with long‐range
           electrostatic interactions
    • Authors: Chunlei Pei; Chuan‐Yu Wu, David England, Stephen Byard, Harald Berchtold, Michael Adams
      Pages: n/a - n/a
      Abstract: To investigate dynamic behaviours of mono‐charged particle systems, a direct truncation (DT) method and a hybrid particle‐cell (HPC) method are implemented into the discrete element method coupled with computational fluid dynamics (DEM‐CFD) with defined cut‐off distances. The DT method only considers electrostatic interactions between particles within the cut‐off distance while the HPC method computes electrostatic interactions in the entire computational domain. The deposition process of mono‐charged particles in a container in air was simulated using the developed DEM‐CFD. It was found that, using DT method, the macrostructure, evolution of granular temperature and radial distribution function of the particle system are sensitive to the specified cut‐off distance. In contrast, using HPC method, these results were independent of the specified cut‐off distance, as expected. This implies that, although electrostatic interactions between particles with large separation distances are weak, they should be considered in DEM‐CFD for accurate modelling of charged particle systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-16T02:29:37.106827-05:
      DOI: 10.1002/aic.14768
       
  • The Role of Wall Deposition and Re‐Entrainment in Swirl Spray Dryers
    • Authors: Víctor Francia; Luis Martín, Andrew E. Bayly, Mark J.H. Simmons
      Pages: n/a - n/a
      Abstract: This article outlines a new experimental method to study fouling in spray dryers and similar devices. In essence, it makes the deposits traceable so that one can quantify the material that comes off the walls, how long it remains there and how the deposits agglomerate with particles in the air. This work focus in a counter‐current swirl spray dryer of detergent, and provides sound evidence that fouling is a dynamic process: clusters form and break at the walls renewing an active layer of deposits. Remarkably, the wall generates >20% of the product and most of the large granules, and increases drastically the residence time of the powder. The assumptions of current numerical models are clearly invalid (i.e. particles rebound at the wall or deposit indefinitely). This article identifies several re‐entrainment mechanisms and their times scales, and accordingly, it proposes a new general framework to describe fouling in a spray dryer. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-16T01:47:19.525483-05:
      DOI: 10.1002/aic.14767
       
  • Multistream Heat Exchangers: Equation‐Oriented Modeling and
           Flowsheet Optimization
    • Authors: Richard C. Pattison; Michael Baldea
      Pages: n/a - n/a
      Abstract: Multistream heat exchangers (MHEXs), typically of the plate‐fin or spiral‐wound type, are a key enabler of heat integration in cryogenic processes. Equation‐oriented modeling of MHEXs for flowsheet optimization purposes is challenging, especially when streams undergo phase transformations. Boolean variables are typically used to capture the effect of phase changes, adding considerable difficulty to solving the flowsheet optimization problem. In this paper, we present a novel optimization‐oriented MHEX modeling approach that uses a pseudo‐transient approach to rapidly compute stream temperatures without requiring boolean variables. The model also computes an approximate required heat exchange area in order to determine the optimal tradeoff between operating and capital expenses. Subsequently, we show that this model seamlessly integrates in a previously‐introduced pseudo‐transient process modeling and flowsheet optimization framework. We illustrate our developments with two optimal design case studies, an MHEX representative of air separation operation and a natural gas liquefaction process. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-16T01:06:59.127739-05:
      DOI: 10.1002/aic.14766
       
  • Bubble Generation Rules in Microfluidic Devices with Micro‐Sieve
           Array as Dispersion Medium
    • Authors: C. Zheng; B.C. Zhao, K. Wang, G.S. Luo
      Pages: n/a - n/a
      Abstract: Microfluidic devices with micro‐sieve array as the dispersion medium have been well recognized. However, few studies have been made on gas‐liquid two‐phase flow in micro‐sieve dispersion devices. In this work, the bubble generation rules with single‐pore, radial‐array pores, axial‐array pores and square‐array pores were systematically investigated. The rules of pore activation have been suggested by considering the capillary force, flow resistances of both dispersed phase and continuous phase. An empirical equation and a theoretical equation to predict the activation of pores in microfluidic devices were developed. An equation to correlate the average bubble diameter with parameter of channel structure, phase ratio and Ca number of continuous phase was also developed. We proposed the strategy of design and scaling up for micro‐sieve devices. Meanwhile we designed a device with dual‐size pores according to the rules derived in this work. This device achieved much better dispersion performance. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-16T01:01:50.321749-05:
      DOI: 10.1002/aic.14765
       
  • Issue information
    • Pages: i - i
      Abstract: “A transmission electron microscope image of redblood‐cell‐membranecoated polymeric nanoparticles. The characteristic spherical core ‐shell structure reflects the enclosure of each polymeric core in a thin membrane shell. The image is obtained after staining the sample with uranyl acetate.” Courtesy of Liangfang Zhang laboratory at UC San Diego. 10.1002/aic.14735
      PubDate: 2015-02-13T14:46:36.098137-05:
      DOI: 10.1002/aic.14582
       
  • John M. Prausnitz: Bridging abstractions and realities
    • Authors: John P. O'Connell
      Pages: n/a - n/a
      Abstract: This Founders Tribute issue honors John Prausnitz as an exceptional intellectual leader, scholar, and educator. This article summarizes how John has impacted chemical engineering. His early vision of connecting fundamental molecular theory to practical thermodynamic applications with Molecular Thermodynamics was an essential element in our profession's paradigm shift from empiricism to engineering science. John's writings and lectures have transformed our core knowledge and guided its utilization into areas well outside traditional engineering bounds. Further, he has vigorously advocated for technology to be considered in the context of all of life and as a human enterprise. Finally, John's personal interactions across generations and disciplines have inspired the personal and professional development of a vast community of students, coworkers, and colleagues. In countless ways, John Prausnitz has influenced the contemporary foundation and functioning of chemical engineering and of realms beyond. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-12T19:13:32.180393-05:
      DOI: 10.1002/aic.14761
       
  • Viscosity and density of isobutane measured in wide ranges of temperature
           and pressure including the near‐critical region
    • Authors: Sebastian Herrmann; Egon Hassel, Eckhard Vogel
      Pages: n/a - n/a
      Abstract: Accurate ηρpT data for isobutane were measured for nine isotherms between 298.15 K and 498.15 K using simultaneously a vibrating‐wire viscometer and a single‐sinker densimeter. The maximum pressure was 93 % of the saturated for subcritical isotherms and 30 MPa for supercritical isotherms. The density measurements are generally characterized by an uncertainty of ≤ 0.1 %. Allocation errors for temperature and pressure influence significantly their uncertainty in the near‐critical region. A comparison with the equation of state by Bücker and Wagner shows agreement normally within ±0.1 %. The near‐critical isotherm 410.15 K reveals differences to –3.7 % exceeding the uncertainty of 1.9 %. The uncertainty in viscosity is ≤ 0.3 %. The comparison with the correlation of Vogel et al. yields deviations exceeding the uncertainty of the correlation (3 %). The critical enhancement becomes evident for the near‐critical isotherm amounting to 1.4 %. The new data will improve the viscosity surface correlation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-12T19:13:24.063718-05:
      DOI: 10.1002/aic.14759
       
  • Methylcyclohexane dehydrogenation for hydrogen production via a bimodal
           catalytic membrane reactor
    • Authors: Lie Meng; Xin Yu, Takuya Niimi, Hiroki Nagasawa, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
      Pages: n/a - n/a
      Abstract: The dehydrogenation of methylcyclohexane (MCH) to toluene (TOL) for hydrogen production was theoretically and experimentally investigated in a bimodal catalytic membrane reactor, that combined Pt/Al2O3 catalysts with a hydrogen‐selective organosilica membrane prepared via sol‐gel processing using bis(triethoxysilyl) ethane (BTESE). Effects of operating conditions on the membrane reactor performance were systematically investigated, and the experimental results were in good agreement with those calculated by a simulation model with a fitted catalyst loading. With H2 extraction from the reaction stream to the permeate stream, MCH conversion at 250°C was significantly increased beyond the equilibrium conversion of 0.44 to 0.86. Because of the high H2 selectivity and permeance of BTESE‐derived membranes, a H2 flow with purity higher than 99.8% was obtained in the permeate stream, and the H2 recovery ratio reached 0.99 in a pressurized reactor. A system that combined the catalytic membrane reactor with a fixed‐bed pre‐reactor was proposed for MCH dehydrogenation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-11T18:11:31.764028-05:
      DOI: 10.1002/aic.14764
       
  • Modelling of a membrane reactor system for crude palm oil
           transesterification. Part II: Transport phenomena
    • Authors: Pin Pin Oh; Mei Fong Chong, Harrison Lik Nang Lau, Junghui Chen, Yuen May Choo
      Pages: n/a - n/a
      Abstract: The mechanistic modeling of biodiesel production process in membrane reactor with the consideration of chemical reaction, phase equilibrium and ultrafiltration is important for the membrane reactor design. In part II of this work, the chemical and phase equilibrium model (CPE) for crude palm oil transesterification reaction in the membrane reactor developed in part I is extended to an integration of CPE with modified Maxwell‐Stefan model, which considers multicomponent mass transport phenomena of concentration polarization and intra‐membrane. A good fit of simulated permeate fluxes and apparent solute rejection to the experimental data shows that the model has a good prediction capability. Reversible fouling was found to be the major fouling and no pore plugging was observed. Simulation results verified that micelles were retained by the membrane at CPO:MEOH molar ratio of 1:24 and catalyst concentration of 0.5wt%. However, phase inversion happened when catalyst concentration of 0.05wt% and 0.1wt% were used. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-11T18:01:00.962081-05:
      DOI: 10.1002/aic.14763
       
  • Uncertainty Quantification of Property Models: Methodology and Its
           Application to CO2‐Loaded Aqueous MEA Solutions1
    • Authors: Joshua C. Morgan; Debangsu Bhattacharyya, Charles Tong, David C. Miller
      Pages: n/a - n/a
      Abstract: Uncertainties in property models can significantly affect the results obtained from process simulations. If these uncertainties are not quantified, optimal plant designs based on such models can be misleading. With this incentive, a systematic, generalized uncertainty quantification (UQ) methodology for property models is developed in this work. Starting with prior beliefs about parametric uncertainties, a Bayesian method is used to derive informed posteriors by using the experimental data. To reduce the computational expense, surrogate response surface models are developed. For down‐selecting the parameter space, a sensitivity matrix‐based approach is developed. The methodology is then deployed to the property models for an MEA‐CO2‐H2O system. The UQ analysis is found to provide interesting information about uncertainties in the parameter space. The sensitivity matrix approach is also found to be a valuable tool for reducing computational expense. Finally, the effect of the estimated parametric uncertainty on CO2 absorption and MEA regeneration is analyzed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-11T10:08:20.996547-05:
      DOI: 10.1002/aic.14762
       
  • State of Health Estimation of Lithium‐ion Batteries: A Multiscale
           Gaussian Process Regression Modeling Approach
    • Authors: Yi‐Jun He; Jia‐Ni Shen, Ji‐Fu Shen, Zi‐Feng Ma
      Pages: n/a - n/a
      Abstract: This investigation studies accurate state of health (SOH) estimation in lithium‐ion batteries, which plays a significant role not only in state of charge (SOC) estimation but also in remaining useful life (RUL) prognostics. SOC estimation and RUL prognostics often require one‐step‐ahead and long‐term SOH prediction respectively. In this study, a systematic multiscale Gaussian process regression (GPR) modeling method is proposed to tackle accurate SOH estimation problems. Wavelet analysis method is utilized to decouple global degradation, local regeneration and fluctuations in SOH time series. GPR with the inclusion of time index is utilized to fit the extracted global degradation trend, and GPR with the input of lag vector is designed to recursively predict local regeneration and fluctuations. The proposed method is validated through experimental data from lithium‐ion batteries degradation test. Both one‐step‐ahead and multi‐step‐ahead SOH prediction performances are thoroughly evaluated. The satisfactory results illustrate that the proposed method outperform GPR models without trend extraction. It is thus indicated that the proposed multiscale GPR modeling method can not only be greatly helpful to both RUL prognostics and SOC estimation for lithium‐ion batteries, but also provide a general promising approach to tackle complex time series prediction in health management systems. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-09T07:54:12.818072-05:
      DOI: 10.1002/aic.14760
       
  • Gas/Liquid/Liquid Three‐Phase Flow Patterns and Bubble/Droplet Size
           Laws in a Double T‐Junction Microchannel
    • Authors: Kai Wang; Kang Qin, Yangcheng Lu, Guangsheng Luo, Tao Wang
      Pages: n/a - n/a
      Abstract: The double T‐junction microchannel is a classical microstructured chemical device used to generate gas/liquid/liquid three‐phase microflows. An experimental study that focused on the three‐phase flow phenomena and bubble/droplet generation rules in a double T‐junction microchannel was introduced. Based on the published knowledge of gas/liquid and liquid/liquid two‐phase microflows, new flow patterns were carefully defined: bubble cutting flow, spontaneous break‐up and bubble cutting coupling flow, and bubble/droplet alternate break‐up flow. According to the classical correlations of bubble and droplet volumes and their generation frequency ratio, the operating criteria for creating different three‐phase flow patterns were established and a model for the dimensionless average bubble and droplet volumes in the three‐phase microflows was developed. These various three‐phase microflows have great application potential in material science and flow chemistry synthesis. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-06T03:46:51.819818-05:
      DOI: 10.1002/aic.14758
       
  • Twenty‐One New Theoretically‐Based Cubic Equations of State
           for Athermal Hard‐Sphere Chain Pure Fluids and Mixtures
    • Authors: Arthur S. Gow; Robert B. Kelly
      Pages: n/a - n/a
      Abstract: Eight new hard‐sphere equations of state (EOS's) were obtained from molecular simulation data for the pair correlation function gHS(σ) versus packing fraction η and combined with three theoretical schemes to obtain twenty‐one new cubic EOS's for athermal hard‐sphere chains (AHSC's). The eight new hard‐sphere EOS models successfully reproduced isotropic fluid compressibility factor ZHS and gHS(σ) versus η simulation data and predicted metastable liquid ZHS versus η and virial coefficients up through B10. Moreover, calculated Z versus η and reduced second‐virial coefficient versus chain length m were compared with molecular simulation data for chains up to m=201 for a set of representative (eight of twenty‐one) chain equations. Z versus η for three AHSC binary mixtures was also successfully predicted. The results indicate that the new cubic EOS's give a satisfactory representation of simulation data for chain fluids and can be used to develop theoretically‐based cubic EOS's for “real” fluids including attractive effects. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-06T02:51:46.315332-05:
      DOI: 10.1002/aic.14757
       
  • Suspending a Solid Sphere in Laminar Inertial Liquid Flow –
           Experiments and Simulations
    • Authors: Junyuan Mo; Zhengming Gao, Zhipeng Li, Yuyun Bao, J.J. Derksen
      Pages: n/a - n/a
      Abstract: The critical conditions for the suspension of single, spherical solid particles by a liquid flow in a square container driven by a rotating disk have been determined. In the experiments, the motion of the sphere has been visualized quantitatively. The conditions are such that the flow in the container is laminar (Reynolds numbers based on the rotating disk characteristics are in the range 10 – 40). The Archimedes numbers of the spheres are of order 1. The suspension process has also been numerically simulated with full resolution of the liquid flow, including the flow around the sphere, and the translational and rotational motion of the sphere. The simulations recover the critical conditions to within 3% in terms of the rotational speed of the disk. Also the sphere's trajectory in the container is reproduced well by the simulations. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-06T02:45:29.967645-05:
      DOI: 10.1002/aic.14756
       
  • Analysis of slot coating flow under tilted die
    • Authors: Semi Lee; Jaewook Nam
      Pages: n/a - n/a
      Abstract: Slot coating is a high precision coating method used to control the film thickness using the flow rate fed to the die and the speed of the substrate or web. The range of desirable operating conditions for uniform coating is limited by the shape and locations of upstream and downstream menisci, which are controlled by the pressure gradient within the coating flow. The gradient can be controlled by the shape and orientation of the slot coating die, i.e., die configuration. Here, we considered the tilted die, the so‐called angle‐of‐attack configuration. The configuration is similar to underbite and overbite configurations, but it has a sloped die lip due to tilting. Coating flows with such a configuration are examined by computer‐aided analysis using the Galerkin/finite element method. Using steady‐state analysis, the effect of the angle of attack on the upstream meniscus location is discussed. In transient analysis, the amplitude of the thickness variation is predicted under different types of disturbances, namely flow rate and gap oscillations. The analysis shows that die lip configurations affect the thickness uniformity under periodic disturbances. The effect of die tilting can be similar to or different from the underbite/overbite configurations, depending on the type of oscillation. During the analysis, we found that the flow rate apportioning inside the coating flow and decomposing thickness variations into two separating oscillations are useful in understanding the results. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-03T02:30:01.245893-05:
      DOI: 10.1002/aic.14752
       
  • Experimental determination of maximum effective hydrodynamic stress in
           multiphase flow using shear sensitive aggregates
    • Authors: Thomas K. Villiger; Massimo Morbidelli, Miroslav Soos
      Pages: n/a - n/a
      Abstract: Maximum effective hydrodynamic stress, τmax, responsible for the breakup of aggregates with size comparable to Kolmogorov eddies, was experimentally determined in an aerated stirred tank. The proposed method is based on the measurement of the maximum stable aggregates size consisting of poly(methyl methacrylate) nanoparticles. The fractal aggregates were broken under various operating conditions in an aerated stirred tank and calibrated with known flow conditions using contracting nozzles to convert the measured aggregate sizes into hydrodynamic stress. It was found that τmax can vary substantially among studied conditions and its magnitude depends on the controlling mechanism including gas jet during bubble formation, bubble rise, bubble burst at the gas‐liquid interface or the turbulence generated by the impeller. The measured values are in good agreement with literature data which supports the applicability of this method to characterize the maximum effective hydrodynamic stress in complicated multiphase flow. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-02T12:50:52.950001-05:
      DOI: 10.1002/aic.14753
       
  • Simple control structure for a compression purification process in an
           oxy‐combustion power plant
    • Authors: William L. Luyben
      Pages: n/a - n/a
      Abstract: The composition of the stack gas from an oxy‐combustion power plant is about 75 mol% carbon dioxide. The stream must be purified to about 95 mol% by removing light inerts such as nitrogen, oxygen and argon. The product stream must be compressed to 110 bar for sequestration. This paper presents a simple control structure for the double‐flash compression and purification process to achieve these objectives. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-02T12:50:32.302691-05:
      DOI: 10.1002/aic.14754
       
  • Renewable fuels from biomass: Technical hurdles and economic assessment of
           biological routes
    • Authors: Daniel Klein‐Marcuschamer; Harvey W. Blanch
      Pages: n/a - n/a
      Abstract: Lignocellulosic biomass is an abundant, renewable source of polysaccharides that could be available in amounts sufficient to provide a source of sugars for carbon neutral biofuel production. We review the background to biofuels production in the US from corn sugars and subsequent R and D efforts to saccharify plant biomass to provide an alternative sugar source. Research efforts and programs have generally not addressed the key technical hurdles in providing a commodity‐scale supply of biomass and in developing biological routes to saccharify it at high yields. Techno‐economic analyses of proposed processes highlight the importance of biomass cost and the role of pretreatment on both inhibitor generation and the contribution of enzyme costs to saccharification. Alternatives, such as the production of fatty acids by microalgae, have comparable technical hurdles. Although there is a regulatory framework for biofuels, which is discussed, a credible biological process for large‐scale, cost‐effective production of lignocellulosic biofuels remains elusive. This article is protected by copyright. All rights reserved.
      PubDate: 2015-02-02T12:50:14.240399-05:
      DOI: 10.1002/aic.14755
       
  • Catalytic hydrothermal liquefaction of D. tertiolecta for the production
           of bio‐oil over different Acid/base catalysts
    • Authors: Yu Chen; Yulong Wu, Ranran Ding, Pan Zhang, Ji Liu, Mingde Yang
      Pages: n/a - n/a
      Abstract: In this paper, two acid catalysts (ZrO2/SO42‐ and HZSM‐5) and two base catalysts (MgO/MCM‐41 and KtB) were employed in catalytic hydrothermal liquefaction (HTL) of D. tertiolecta for the production of bio‐oil. The results indicated that the acid/base property of the catalyst plays a crucial role in the catalytic HTL process, and the base catalyst is conducive to the improvement of conversion and bio‐oil yield. When KtB was used as the catalyst, the maximum conversion and bio‐oil yield was 94.84 and 49.09 wt.%, respectively. The detailed compositional analysis of the bio‐oil was performed using TGA, EA, FT‐IR, and GC‐MS. The compositional analysis results showed that the introduction of catalyst is beneficial for reducing the fixed carbon content in the bio‐oil, and the structure of catalyst influences on the bio‐oil composition and boiling point distribution. Based on our results and previous studies, the probable catalytic HTL microalgae model over various catalysts can be described that the main chemical reactions include ketonization, decarboxylic, dehydration, ammonolysis, etc. with HZSM‐5 and MgO/MCM‐41 as the catalyst; the cyclodimerization, decomposition, Maillard reaction and ketonization are the main reactions with ZrO2/SO42‐ as the catalyst; the dehydration, ammonolysis, Maillard reaction and ketonization can occur with KtB as the catalyst. Therefore, a plausible reaction mechanism of the main chemical component in D. tertiolecta is proposed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-30T02:41:42.587022-05:
      DOI: 10.1002/aic.14740
       
  • Mean Drop Size Correlations and Population Balance Models for Liquid
           – Liquid Dispersion
    • Authors: Mohd Izzudin Izzat Zainal Abidin; Abdul Aziz Abdul Raman, Mohamad Iskandr Mohamad Nor
      Pages: n/a - n/a
      Abstract: Reliable models are required for accurate estimation of drop sizes which govern the interfacial area and rate of mass transfer in a system where various correlations and models have been improved for better accuracy and wider application breath. In this paper, relevant semiempirical equations and population balance equation models are reviewed. Semi‐empirical correlations are highly system dependent and limited to prediction of steady‐state drop size while population balance equation models could estimate transient drop size with considerations of inhomogeineity and flow spatial variation during drop size evolution. With appropriate model parameters determination, different population balance equation models can be used to reproduce experimental data for a similar system. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-29T06:04:26.175193-05:
      DOI: 10.1002/aic.14751
       
  • Ammonia synthesis enhanced by magnesium chloride absorption
    • Authors: Heath H. Himstedt; Mark S. Huberty, Alon V. McCormick, Lanny D. Schmidt, E. L. Cussler
      Pages: n/a - n/a
      Abstract: Conversion to ammonia with Haber–Bosch catalysts can be increased above 95% by selective absorption of ammonia by MgCl2. The maximum conversion depends on reaction and absorption equilibria. At very short times, the measured conversion rate is the same with and without absorption by the MgCl2 salt; the overall rate constants are comparable to those in the literature. At larger times, conversion to ammonia can be over seven times greater with MgCl2 than without. However, the overall rate constants can be over 10 times slower because they are controlled by ammonia diffusion in the solid salt. An approximate, pseudosteady state theory consistent with these results provides a strategy for improving the overall rate while keeping the conversion over 90%. For example, the absorption rates might be increased using smaller particles of absorbent on a porous inert absorbent support. The results provide part of the basis for designing small scale ammonia plants. © 2015 American Institute of Chemical Engineers AIChE J, 2015
      PubDate: 2015-01-27T12:57:42.884983-05:
      DOI: 10.1002/aic.14733
       
  • A Fan‐Equipped Reactor for Dust Explosion Tests
    • Authors: Almerinda Di Benedetto; Paola Russo, Roberto Sanchirico, Valeria Di Sarli
      Pages: n/a - n/a
      Abstract: A CFD model was developed with the aim at simulating the turbulent flow field and associated dust dispersion in an agitated spherical explosion vessel. Simulations were performed in the presence of two counter‐rotating fans and also after having switched‐off the fans. Numerical results have shown that the dust mainly accumulates at the center of the sphere in the space left by the four vortices formed. After the switch‐off of the fans, the dust particles start filling the empty volumes inside the sphere, reaching a quite uniform distribution (with concentration equal to the nominal value) and simultaneously ensuring a controlled value of turbulent kinetic energy. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-23T21:56:16.3167-05:00
      DOI: 10.1002/aic.14750
       
  • A novel Induction Heating Fluidized Bed Reactor for Screening Tests of
           Solid Feedstocks
    • Authors: Mohammad Latifi; Jamal Chaouki
      Pages: n/a - n/a
      Abstract: A novel mini induction heating fluidized bed reactor (IHFBR) is introduced which was developed to carry out screening tests of high temperature reactions up to 1500 °C particularly for solid feedstocks. Despite conventional mini reactors, this reactor mimics real scenario of solid feeding in industrial reactors: cold feedstock is injected within one second from a lift tube, then particles reach reaction temperature in less than 5 seconds in a reaction zone. The lift tube (9.5 cm diameter) is also gas distributor of the fluidized bed (2.5 cm diameter) so that the bed is completely fluidized with uniform gas distribution. Beside facilities to perform tests in a fluidized bed, another important feature of this reactor is prediction of the defluidization state in the bed. Not only reproducible data are generated, but also many tests can be conveniently carried out i.e. one test per hour. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-23T21:31:05.541822-05:
      DOI: 10.1002/aic.14749
       
  • Combined Generative Topographic Mapping and Graph Theory unsupervised
           approach for non‐linear fault identification
    • Authors: Matheus S. Escobar; Hiromasa Kaneko, Kimito Funatsu
      Pages: n/a - n/a
      Abstract: Identifying anomalies in chemical processes is highly desirable. Usually, one relies on previous knowledge of normal and faulty samples, excluding anomalies from model training and associating deviations to faults. How reliable is such knowledge, however, is questionable, especially during atypical scenarios. Unsupervised approaches, using no labels, provide an unbiased analysis. A Generative Topographic Mapping (GTM) and Graph Theory combined approach, then, is proposed for unsupervised fault identification. GTM, given its probabilistic nature, highlights system features, reducing variable dimensionality. With this information, correlation between samples is calculated. Graph Theory, then, generates a network, clustering similar samples. Two anomaly cases are analyzed: an artificial data set and Tennessee Eastman Process. Principal Component Analysis (PCA) and Dynamic PCA indexes Q and T2 along GTM and Graph Theory independent monitoring methodologies are used for comparison, considering supervised and unsupervised approaches. The proposed method performed similarly to all supervised methodologies, motivating its application and developments. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-23T17:12:30.944479-05:
      DOI: 10.1002/aic.14748
       
  • Influence of heat transfer across the wall of dividing wall columns on
           energy demand
    • Authors: Christoph Ehlers; Moritz Schröder, Georg Fieg
      Pages: n/a - n/a
      Abstract: The implementation of a vertical dividing wall into a distillation column is a well‐known concept which can result in considerable energy savings for the separation of multicomponent mixtures. It is commonly known that heat streams across the dividing wall, which are present due to temperature differences between both sides, may either increase or decrease the energy demand for a certain separation task. However, no work has been published so far which explains the maximum influence on energy demand. This paper derives the maximum extent to which the minimum energy demand for a given column design can change due to heat transfer across the dividing wall. Additionally, it is illustrated how energy‐efficient column operation can be assured even if the total amount of transferred heat is unknown. These results show that the phenomenon of heat transfer across the dividing wall can be handled very well with a suitable control strategy. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-22T16:06:51.730331-05:
      DOI: 10.1002/aic.14747
       
  • Moving ion fronts in mixed ionic‐electronic conducting polymer films
    • Authors: Sarah E. Feicht; George D. Degen, Aditya S. Khair
      Pages: n/a - n/a
      Abstract: We analyze moving front dynamics of ions and holes in a planar, mixed ionic‐electronic conducting polymer film. As cations invade the film, holes evacuate; thus, an ionic current is converted to an electronic signal. Recent experiments [1] show that the location of the advancing ion front increases as the square‐root of time, a scaling typically associated with diffusive transport, which is surprising given the large driving voltages utilized. We model the ionic and electronic transport via the drift‐diffusion equations. A similarity transformation reduces the governing partial differential equations to ordinary differential equations that are solved numerically. The similarity transformation elucidates the origin of the square‐root‐of‐time front scaling. We compare the similarity solution to the numerical solution of the full drift‐diffusion equations, finding excellent agreement. When compared to experimental data, our model captures the front location; however, qualitative differences between the ion profiles are observed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-22T16:06:32.513578-05:
      DOI: 10.1002/aic.14746
       
  • Crystallization of Selective Polymorph Using Relationship between
           Supersaturation and Solubility
    • Authors: Kwang‐Joo Kim; Michael F. Doherty
      Pages: n/a - n/a
      Abstract: For polymorph screening, the plot of ΔCmet/Cc against C*/Cc in nucleation kinetics was investigated. The polymorph screening for forms I and II, and amorphous form of clopidogrel hydrogen sulfate (CHS) was carried out according to the nucleation kinetics expressed by this plot. The stability order of polymorphs for famotidin were also predicted successfully by this model. This model was used in the expectation of supersaturation level for polymorphic formation. Two types of polymorphic crystallization; transformation from metastable form to stable form, and nucleation and growth of polymorphic form without trnsformation can be explained. Amorphous form was also expected by this model. Even though polymorphs depend on lots of crystallization parameters such as solvent, temperature, concentration, cooling rate, etc., plot of ΔCmet/Cc and the C*/Cc in various nucleation kinetics gives a guide line for screening of polymorph. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-22T09:45:32.615941-05:
      DOI: 10.1002/aic.14745
       
  • Experimental and theoretical study of the intrinsic kinetics for dimethyl
           ether synthesis from CO2 over Cu‐Fe‐Zr/HZSM‐5
    • Authors: Zu‐zeng Qin; Tong‐ming Su, Yue‐xiu Jiang, Rui‐wen Liu, Hong‐bing Ji, Jian‐hua Chen
      Pages: n/a - n/a
      Abstract: An intrinsic kinetics model was established for CO2 hydrogenation to dimethyl ether (DME) with a Cu–Fe–Zr/HZSM‐5 catalyst based on H2/CO2 adsorption, simulation and calculation of methanol synthesis from CO2 intermediates, and experimental data. H2/CO2–temperature programmed desorption results show a dissociative H2 adsorption on Cu site; CO2 was linearly adsorbed on Fe3O4 weak base sites of the catalyst; the adsorbing capacity of H2 and CO2 increased after Zr doping. Density functional theory analysis of methanol synthesis from CO2 and H2 revealed a formate pathway. Methanol synthesis was the rate‐limiting step (173.72 kJ·mol−1 activation energy) of the overall CO2 hydrogenation reaction, and formation of H2CO is the rate‐determining step of methanol synthesis. Relative errors between calculated and experimental data of partial pressures of all components were less than 10%. Therefore, the kinetics model may be an accurate descriptor of intrinsic kinetics of CO2 hydrogenation to DME. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-19T17:49:04.763641-05:
      DOI: 10.1002/aic.14743
       
  • An experimental investigation on the influence of phenol on the solubility
           of CO2 in aqueous solutions of NaOH
    • Authors: Michael Jödecke; Jianzhong Xia, Álvaro Pérez‐Salado Kamps, Gerd Maurer
      Pages: n/a - n/a
      Abstract: Experimental results are presented for the solubility of CO2 in an aqueous solution of phenol and NaOH (molalties in water: phenol: 0.5; NaOH: 1.0) at (314, 354, and 395) K and pressures up to 10 MPa. The experimental work extends recent investigations on the influence of phenol as well as of (phenol + NaCl) on the solubility of CO2 in water. In contrast to those previous investigations the strong electrolyte reacts with carbon dioxide and also with phenol. The experimental results are compared with predictions from a thermodynamic model. That model combines a model for the “chemical” solubility of CO2 in aqueous solutions of NaOH with a model for the “physical” solubility of CO2 in aqueous solutions of phenol. An extension is introduced to account for the chemical reaction between the weak acid phenol and the strong base sodium hydroxide. The prediction results nicely agree with the new experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-19T17:48:45.54569-05:0
      DOI: 10.1002/aic.14742
       
  • Microscopic imaging of biphasic oil‐air flow in french fries using
           synchrotron radiation
    • Authors: Anna Patsioura; Jean‐Michaël Vauvre, Régis Kesteloot, Frédéric Jamme, Pamela Hume, Olivier Vitrac
      Pages: n/a - n/a
      Abstract: Spontaneous oil percolation in french fries was studied dynamically at cellular scale using deep‐UV synchrotron radiation enabling to image simultaneously the fluorescence of cell walls and of dyed oil. Experimental results report 75 oil filling kinetics of potato parenchyma cells previously emptied and equilibrated with superheated steam in conditions mimicking immersion frying. Counter‐current oil‐air flow was found the dominant factor controlling the kinetic of oil penetration, whereas trapped bubbles delay the passage of oil from the first to the second cell layer for additional several minutes. The frequency of occurrence of passages between layers was assessed much lower than the percolation threshold suggested by the hierarchical honeycomb arrangement of cells. A description relating microscopic oil‐air flow and oil uptake is detailed in a companion paper. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-19T17:48:29.160882-05:
      DOI: 10.1002/aic.14744
       
  • Understanding cubic equations of state: A search for the hidden clues of
           their success
    • Authors: G. Wilczek‐Vera; J.H. Vera
      Pages: n/a - n/a
      Abstract: This work investigates the hidden details that are responsible for the practical success of cubic equations of state in phase equilibrium calculations. A detailed consideration of the van der Waals method for evaluating the pure compound EOS parameters sheds new light on the reasons why the elimination of the actual critical volume as parameter was also adopted in the Redlich‐Kwong and the Peng‐Robinson frameworks. It is shown that an interesting relationship for the critical compressibility factor arising from the Martin‐Hou method opens a new door for future exploration of different frameworks. A consideration of the key steps of Soave's reasoning for determining the temperature dependence of the attractive parameter explains the larger success of the PRSV EOS over the Peng‐Robinson EOSs. A reference to the extension of cubic EOS to calculate liquid densities and enthalpies and a ready to use algorithm for the evaluation of the roots of a cubic equation are included for instructional purposes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-19T17:48:07.817975-05:
      DOI: 10.1002/aic.14741
       
  • Effect of bed size on hydrodynamics in 3D gas‐solid fluidized beds
    • Authors: Vikrant Verma; Johan T. Padding, Niels G. Deen, J.A.M. Kuipers
      Pages: n/a - n/a
      Abstract: It is well‐known that hydrodynamics observed in large scale gas‐solid fluidized beds are different from those observed in smaller scale beds. In this article, an efficient two‐fluid model based on kinetic theory of granular flow is applied, with the goal to highlight and investigate hydrodynamics differences between three‐dimensional fluidized beds of diameter 0.10, 0.15, 0.30, 0.60 and 1.0m, focusing on the bubble and solids flow characteristics in the bubbling regime. Results for the 0.30m diameter bed are compared with experimental results from the literature. The bubble size evolution closely follows a correlation proposed by Werther for small beds, and a correlation proposed by Darton for sufficiently large beds. The bubble size increases as the bed diameter is increased from 0.10 to 0.30m, and remains approximately constant for bed diameters from 0.30 to 1.0m. Concurrently, an increase in bubble rise velocity is observed, with a much high bubble rise velocity in the largest bed of diameter 1.0m due to gulf stream circulations. The dynamics in shallow and deep beds is predicted to be different, with marked differences in bubble size and solids circulation patterns. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-17T01:50:16.809874-05:
      DOI: 10.1002/aic.14738
       
  • Qualitative path estimation: A fast and reliable algorithm for qualitative
           trend analysis
    • Authors: Kris Villez
      Pages: n/a - n/a
      Abstract: Fault detection and identification is challenged by a lack of detailed understanding of process dynamics under anomalous circumstances as well as a lack of historical data concerning rare events in a typical process. Qualitative trend analysis (QTA) techniques provide a way out by focusing on a coarse‐grained representation of time series data. Such qualitative representations (QRs) are valid in a larger set of operating conditions and are thus provide a robust way to handle the detection and identification of rare events. Unfortunately, available methods fail when faced with moderate noise levels or result in rather large computational efforts. For this reason, this article provides a novel method for QTA. This leads to dramatic improvements in computational efficiency compared to the previously established shape constrained splines (SCS) method while the accuracy remains high. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-17T01:49:57.609894-05:
      DOI: 10.1002/aic.14736
       
  • Mixing strategies for zinc oxide nanoparticle synthesis via a polyol
           process
    • Authors: Mongia Hosni; Samir Farhat, Ivaylo Hinkov, Mounir Ben Amar, Andrei Kanaev, Noureddine Jouini
      Pages: n/a - n/a
      Abstract: We report on the effect of mixing on the morphology of ultrafine zinc oxide nanoparticles synthesized via a polyol process using zinc acetate and water in a diethylene glycol medium. Three mixing strategies were considered: stirred batch, T‐mixer, and impinging free jets. The particle granulometry was accessed using the transmission electron microscopy and X‐ray diffraction methods. The nanoparticle size and polydispersity decreased with an increase in the local dissipated energy. In particular, the polyol process conducted in the same chemical environment at 353K did not lead to the observation of nanoparticles in the stirred batch reactor but resulted in unconventionally small 6‐nm particles in the T‐mixer and impinging jet configurations. This result is apparently related to the micro‐mixing eddy geometry described by the Kolmogorov length. The hydrodynamic flow patterns and energy dissipation were obtained from computational fluid dynamics (CFD) simulations, which are essential in the design, optimization, and scale‐up of the polyol process. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-17T01:49:37.65736-05:0
      DOI: 10.1002/aic.14737
       
  • A class of exact solutions for population balances with arbitrary internal
           coordinates
    • Authors: Tony Saad; Alex W. Abboud, Sean T. Smith, Terry A. Ring
      Pages: n/a - n/a
      Abstract: We develop a novel transformation that maps the linear, non‐homogeneous, multidimensional population balance equation (PBE) into an advection equation that is readily solved using the method of characteristics. The PBEs targeted by this transformation exclude aggregation and breakage. In addition, internal coordinates are assumed to grow independently of each other. The ensuing general formulation is then used to recover closed‐form analytical solutions for problems with monosurface and bulk‐diffusion growth‐rates as well as Gaussian‐type nucleation. For completeness, we derive the multidimensional Green's functions for our approach. This is followed by a brief discussion on how the proposed framework may be used for code‐verification of moment methods such as the quadrature method of moments (QMOM) and the direct quadrature method of moments (DQMOM). Finally, a sample Mathematica code is provided to derive analytical solutions for the single‐internal‐coordinate case given user‐specified growth, birth, and death rates. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-17T01:49:18.583248-05:
      DOI: 10.1002/aic.14739
       
  • Experimental study of hydrodynamics and thermal behavior of a
           pseudo‐2D spout‐fluidized bed with liquid injection
    • Authors: Vinayak S. Sutkar; Niels G. Deen, Amit V. Patil, Elias A.J.F. Peters, J.A.M. Kuipers, Vitalij Salikov, Sergiy Antonyuk, Stefan Heinrich
      Pages: n/a - n/a
      Abstract: A novel nonintrusive technique is presented to investigate hydrodynamic and thermal behavior of gas–solid spout‐fluidized beds with liquid injection, by simultaneously capturing visual and infrared images. Experiments were performed in a pseudo‐2D bed with draft plates filled with glass or γ‐alumina particles to investigate the effect of liquid injection and particle properties on the flow characteristics. For the glass particles under dry and wet conditions, time‐averaged particle velocities show similar quasi‐steady‐state behavior. However, under wet conditions, lower particle velocities were observed in both spout and annulus as compared with the dry system. Whereas, γ‐alumina particles do not show considerable variation in the particle velocities under dry and wet conditions and fluidize well at higher liquid injection rates. Additionally, for the glass particles, the particle temperature significantly decreases as compared to the γ‐alumina particles. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2015-01-10T20:46:53.201407-05:
      DOI: 10.1002/aic.14719
       
  • Engineering red blood cell membrane‐coated nanoparticles for broad
           biomedical applications
    • Authors: Weiwei Gao; Liangfang Zhang
      Pages: n/a - n/a
      Abstract: Using red blood cell (RBC) membrane to coat synthetic nanoparticles has emerged as a robust and versatile approach of integrating natural and man‐made biomaterials to form functional nanostructures. The resulting RBC membrane‐coated nanoparticles (RBC‐NPs) have been garnering increased attention due to their unique capabilities of retaining complex antigenic information and harnessing many of the natural properties displayed by native RBCs. As a result, they have been increasingly applied toward the development of novel nanotherapeutics. In this perspective, we review our recent progress in developing RBC‐NPs as long‐circulating nanocarriers for drug delivery, biomimetic nanosponges for detoxification, and nanotoxoids for safe and effective toxin vaccination. We expect that this biomimetic nanoparticle platform will inspire and enable additional therapeutic advances for better disease intervention and healthcare. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-10T01:12:48.007336-05:
      DOI: 10.1002/aic.14735
       
  • Transient response of two‐layer slot coating flows to periodic
           disturbances
    • Authors: D. Maza; M. S. Carvalho
      Pages: n/a - n/a
      Abstract: Coating uniformity requirement is becoming more severe as new products come into the market. Coating processes have to be designed not only based on the steady state operation, but also taking into account how the flow responds to ongoing disturbances on process conditions. These disturbances may lead to thickness variation on the deposited liquid layers that may be unacceptable for product performance. This study extends available transient analysis of single layer slot coating to determine the amplitude of the oscillation of each individual coated layer in two layer slot coating process in response to small periodic perturbation on different operating parameters. The predictions were obtained by solving the complete transient Navier‐Stokes equations for free surface flows. The results show the most dangerous perturbations and how the deposited film thickness variations of each layer can be minimized by changing the geometry of the die lip and liquid viscosities. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-08T18:09:20.70155-05:0
      DOI: 10.1002/aic.14734
       
  • Modelling and simulation of an industrial‐scale parex process
    • Authors: Marta S. P. Silva; José P. B. Mota, Alírio E. Rodrigues
      Pages: n/a - n/a
      Abstract: The Parex unit for industrial‐scale purification of p‐xylene was studied through detailed simulation and the accuracy of the developed model tested against real industrial data. Starting from a comprehensive analysis of the construction and operation of the industrial unit, a simulation model was developed that incorporates the existing three major types of dead volumes: bed lines, which connect the beds to the rotary valve, circulation lines, which connect adjacent adsorbent chambers, and bed‐head dead volumes, which are located upstream of each bed due to the existence of internals. By gathering operation data and surveys in the pumparound line and in the extract stream, three case studies were defined and compared with simulation results. The model is capable of predicting the performance of the industrial unit. Further simulations were made and compared with plant data to assess the effect of adsorbent capacity loss on the long‐term performance of the unit. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-08T17:08:04.014638-05:
      DOI: 10.1002/aic.14732
       
  • Co‐production of liquid transportation fuels and C6_C8 aromatics
           from biomass and natural gas
    • Authors: Alexander M. Niziolek; Onur Onel, Josephine A. Elia, Richard C. Baliban, Christodoulos A. Floudas
      Pages: n/a - n/a
      Abstract: The co‐production of liquid transportation fuels and C6‐C8 aromatics from the thermochemical conversion of biomass and natural gas (BGTL+C6_C8) is investigated in this paper. An optimization‐based process synthesis framework incorporating multiple synthesis gas conversion technologies, such as Fischer‐Tropsch synthesis or methanol conversion, is described. Production of aromatics can proceed through several technologies, such as naphtha reforming and aromatization of hydrocarbons via a metal‐promoted H‐ZSM‐5 catalyst. This is the first paper in the literature to incorporate an aromatics complex for the co‐production of liquid fuels and C6‐C8 petrochemicals within a rigorous process synthesis and deterministic global optimization framework. The optimal process topologies across several case studies are discussed and the results indicate that the co‐production of aromatics with liquid fuels can significantly increase the profitability of these refineries. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-07T12:46:27.610834-05:
      DOI: 10.1002/aic.14726
       
  • Air separation with cryogenic energy storage: Optimal scheduling
           considering electric energy and reserve markets
    • Authors: Qi Zhang; Clara F. Heuberger, Ignacio E. Grossmann, Arul Sundaramoorthy, Jose M. Pinto
      Pages: n/a - n/a
      Abstract: The concept of cryogenic energy storage (CES) is to store energy in the form of liquid gas and vaporize it when needed to drive a turbine. Although CES on an industrial scale is a relatively new approach, the technology is well‐known and essentially part of any air separation unit (ASU) that utilizes cryogenic separation. In this work, we assess the operational benefits of adding CES to an existing air separation plant. We investigate three new potential opportunities: (1) increasing the plant's flexibility for load shifting, (2) storing purchased energy and selling it back to the market during higher‐price periods, (3) creating additional revenue by providing operating reserve capacity. We develop a mixed‐integer linear programming (MILP) scheduling model and apply a robust optimization approach to model the uncertainty in reserve demand. The proposed model is applied to an industrial case study, which shows significant potential economic benefits. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-07T12:16:55.894649-05:
      DOI: 10.1002/aic.14730
       
  • Countercurrent gas−solid trickle flow reactor with structured
           packing: Hydrodynamics and CaO−CO2 reaction
    • Authors: Ana Obradović; Janez Levec
      Pages: n/a - n/a
      Abstract: The sorption reaction CaO−CO2 was examined in a countercurrent gas−solid trickle flow reactor with regularly stacked packing at T = 500 − 600 °C, pCO2 = 40 − 50 kPa, solid‐phase fluxes S = 0.3 − 0.5kg m−2s−1, and CaO particles of 500 − 710 μm in size. Sorption kinetics was evaluated by thermogravimetric (TG) technique. The random pore model was used for the description of the carbonization reaction. Hydrodynamic characteristics of gas−solid trickle flow were estimated at room temperature and ambient pressure. Plug flow model of both gas and solid‐phase, with the parameters obtained from TG and hydrodynamics experiments, satisfactorily described the sorption process in countercurrent gas−solid trickle flow reactor. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-07T12:16:37.737433-05:
      DOI: 10.1002/aic.14731
       
  • On the use of the generalized autocatalytic models: The thermal
           decomposition of 3,5‐dinitro‐4‐methylbenzoic Acid
    • Authors: Roberto Sanchirico
      Pages: n/a - n/a
      Abstract: The thermal decomposition of 3,5‐dinitro‐4‐methylbenzoic acid is studied by means of differential calorimetric techniques (DSC). Its autocatalytic behaviour has been highlighted and the decomposition process has been described considering the generalized expression of the Šesták‐Berggren model. A new procedure for the optimization of the initiation parameter along with the other Arrhenius and kinetic exponents starting from the knowledge of the classic Šesták‐Berggren model is illustrated. Encouraging results point out the validity of the approach which has been verified considering both a series of numerical and real experiments. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-05T15:11:12.094277-05:
      DOI: 10.1002/aic.14729
       
  • Removal of Hg0 from flue gas using two homogeneous
           Photo‐Fenton‐Like reactions
    • Authors: Yangxian Liu; Jun Zhang, Yanshan Yin
      Pages: n/a - n/a
      Abstract: Removal of Hg0 using two homogeneous Photo‐Fenton‐Like reactions was firstly investigated in a photochemical reactor. Effects of process parameters on Hg0 removal were studied. Free radical and reaction products were analyzed. Removal pathways of Hg0 were discussed. Simultaneous removal of Hg0, NO and SO2 is also studied briefly. The results show that UV power, wavelength, H2O2 concentration and solution pH have great effects on Hg0 removal. Hg0 and SO2 concentrations, solution temperature, Fe3+, Cu2+, CO32‐ and HCO3‐ concentrations also have significant effects on Hg0 removal. However, concentrations of CO2, NO, O2, Cl‐, NO3‐, SO42‐, SiO2, Al2O3 and Fe2O3 only have slight effects on Hg0 removal. Hg0/NO/SO2 can be simultaneously removed by Photo‐Fenton‐Like reactions. ·OH was captured, and SO42‐/NO3‐/Hg2+ were also detected. Removals of Hg0 by photochemical oxidation and ·OH oxidation play a major role, and removal of Hg0 by H2O2 oxidation only plays a secondary role in removal of Hg0. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-05T15:09:53.940271-05:
      DOI: 10.1002/aic.14727
       
  • Experimental investigation of electrostatic effect on bubble behaviors in
           gas‐solid fluidized bed
    • Authors: Kezeng Dong; Qing Zhang, Zhengliang Huang, Zuwei Liao, Jingdai Wang, Yongrong Yang
      Pages: n/a - n/a
      Abstract: Electrostatics and hydrodynamics in the fluidized bed are mutually affected, and excess accumulation of electrostatic charges has a severe impact on hydrodynamics. However, there is a serious lack of experimental investigation of electrostatic effect on hydrodynamics. This work provides a first insight into the electrostatic effects on bubble behaviors experimentally by injecting a trace of liquid antistatic agents (LAA) into a fluidized bed. Different amounts of LAA (0~50 ppm) were injected to make the electrostatic charges vary in a wide range and the bubble behaviors were investigated simultaneously. Results showed that the charges on particles decreased with increasing amount of LAA, which resulted in larger bubble sizes, stronger fluctuations of dynamic bed height and less wall sheeting, respectively. The maximum reduction ratio of bubble sizes due to electrostatic effect was 21%. When particles were charged, the bubble sizes were significantly smaller than those estimated from the classical correlation. This discrepancy was attributed to the neglect of electrostatic effect in classical correlation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-05T15:09:36.087657-05:
      DOI: 10.1002/aic.14725
       
  • A comparison of flow development in high density gas‐solids
           circulating fluidized bed downer and riser reactors
    • Authors: Chengxiu Wang; Chunyi Li, Shahzad Barghi, Jesse Zhu
      Pages: n/a - n/a
      Abstract: Comparison of flow development in high density downer and riser reactors is experimentally investigated using FCC particles with very high solids circulation rate up to 700 kg/m2s for the first time. Results show that both axial and radial flow structures are more uniform in downers compared to riser reactors even at very high density conditions, although the solids distribution becomes less uniform in the high density downer. Solids acceleration is much faster in the downer compared to the riser reactor indicating a shorter length of flow development and residence time, which is beneficial to the chemical reactions requiring short contact time and high product selectivity. Slip velocity in risers and downers is also firstly compared at high density conditions. The slip velocity in the downer is much smaller than in the riser for the same solids holdup indicating less particle aggregation and better gas‐solids contacting in the downer reactors. This article is protected by copyright. All rights reserved.
      PubDate: 2015-01-05T15:09:18.728524-05:
      DOI: 10.1002/aic.14728
       
  • Impact of flue gas radiative properties and burner geometry in furnace
           simulations
    • Authors: Yu Zhang; Carl M. Schietekat, Feng Qian, Kevin M. Van Geem, Guy B. Marin
      Pages: n/a - n/a
      Abstract: Three fully coupled Computational Fluid Dynamics (CFD) simulations of a complete industrial steam cracking furnace equipped with floor burners are performed. The influence of the flue gas radiative properties and burner geometry on the flame front in the firebox, the heat transfer to the coils and the product selectivities has been investigated. A nine‐band model developed from the Exponential Wide Band Model (EWBM) is used as non‐gray gas radiation model to compare with the gray gas implementation of Weighted Sum of Gray Gas Model (WSGGM) for the evaluation of the flue gas radiative properties. The gray gas radiation model predicts a flue gas outlet temperature that is 70K lower than the temperature obtained with the non‐gray gas radiation model, resulting in a 3.6% higher thermal efficiency and 44K higher average Coil Outlet Temperature (COT). Important differences between the 22 reactors in the furnace are seen because of shadow effects with and without accounting for the detailed burner geometry. The maximum difference between the COT of different reactors in the furnace caused by shadow effects is about 29K which corresponds to a propene‐over‐ethene difference of 0.1. Full furnace CFD simulations prove thus to be essential in design and during debottlenecking, when aiming for a more uniform COT distribution to the reactors by feed or fuel distribution. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-30T14:07:09.156856-05:
      DOI: 10.1002/aic.14724
       
  • Semi‐analytical characterization of turbulence from radial
           impellers, with experimental and numerical validation
    • Authors: R. Ben‐Nun; B. Kysela, J. Konfršt, I. Fořt, M. Sheintuch
      Pages: n/a - n/a
      Abstract: We characterize turbulent flow from radial impellers in stirred tanks, formulating semi‐analytical predictions based on conventional turbulent‐jet theory and the general framework of scalar dispersion in turbulent shear flows. This work introduces a novel formulation of the radial‐discharge flow as two separate spatial regions along the radial axis: the zone of flow establishment (ZFE) and the zone of established flow (ZEF). We discover and analyze resulting critical improvements in the prediction of key parameters of turbulent kinetic energy and associated dissipation rate. Further, we derive and examine functional forms of the random turbulence in the ZFE region, based upon empirical inputs of averaged radial velocity as well as related calibration coefficients. Finally, we validate this new theoretical framework, both with laser Doppler anemometry (LDA) measurements, and with three‐dimensional numerical simulations using the standard k‐ε turbulent model. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-30T13:29:34.732504-05:
      DOI: 10.1002/aic.14723
       
  • An analytical relationship of concentration dependent interfacial solute
           distribution coefficient for aqueous layer freeze concentration
    • Authors: Xiao Dong Chen; Ping Chen, Duo Wu
      Pages: n/a - n/a
      Abstract: Freeze concentration (FC) is a sub‐zero temperature solute concentration procedure, favoring the retention of high quality compounds such as food ingredients and biological materials. It is known that modeling solute inclusion in the ice layers or ice crystals formed in a convective environment requires the solute distribution coefficient function. The fluid flow velocity, ice‐growth rate and solute concentration are influential on this function. Some literature has reported certain expressions of the function, which are relatively complex. Here, an explicit format of this function has been derived for single solute system, and found to be satisfactory in correlating a wide range of experimental data on sucrose solutions for both the controlled flow layer crystallization process (flow in between two cooling plates) as well as the falling film crystallization process. This expression has captured the fundamental aspects of mass transfer and it is relatively simple which should be very useful for correlating FC parameters and for simulating the layer freeze concentration processes. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-30T12:56:27.397096-05:
      DOI: 10.1002/aic.14722
       
  • Shear stability of inverse latexes during their polymerization process
    • Authors: Stefano Lazzari; Baptiste Jaquet, Hua Wu, Massimo Morbidelli
      Pages: n/a - n/a
      Abstract: We study the shear‐stability of inverse latexes (IL) during their polymerization process. The IL is made of water droplets containing a copolymer of acrylamide and dimethyl‐aminoethyl‐methylenechloride emulsified in a paraffin oil. It is found for the first time that the shear stability of the ILs is a non‐monotonic function of the monomer conversion. At low conversions the shear stability increases as the conversion increases, but at a certain conversion value it reaches a local maximum and then decreases with conversion. Moreover, at the final stage of the conversion, the shear stability can increase again. A proper interpretation of this behavior is proposed and related to the combined effects of the polymer properties, fractal aggregation and coalescence. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-30T12:21:41.307665-05:
      DOI: 10.1002/aic.14721
       
  • Synthesis and application of ethylenediamine tetrapropionic salt as a
           novel draw solute for forward osmosis application
    • Authors: Qingwu Long; Guangxian Qi, Yan Wang
      Pages: n/a - n/a
      Abstract: The development of suitable draw solutes for forward osmosis (FO) process is a big obstacle on the way of its real industrialization. In this work, a novel draw solute, ethylenediamine tetrapropionic (EDTP) acid (salt) is developed for FO application. The successful synthesis is confirmed by FTIR, NMR, and HRMS. By optimizing the pH of EDTP solution, its composition is varied and therefore its water solubility and osmotic pressure are effectively improved. The effects of EDTP concentration on the osmotic pressure and FO performance are also investigated. Its outstanding osmotic pressure and big molecular size result in a high water flux of 22.69 LMH and a low salt flux of 0.32 gMH with 0.8M EDTP draw solution (water as the feed solution, PRO mode). The good stability and easy recovery by nanofiltration of EDTP solution also demonstrate its great potential as the draw solute for future FO applications. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-30T12:02:29.598703-05:
      DOI: 10.1002/aic.14720
       
  • Impact of the Diffusion Limitation in Microphotoreactors
    • Authors: Tristan Aillet; Karine Loubière, Odile Dechy‐Cabaret, Laurent Prat
      Pages: n/a - n/a
      Abstract: This publication describes a model that aims (i) to predict the performances (conversion, photonic efficiency) of a photochemical reaction at the outlet of a microreactor. To achieve this, a set of equations that couple mass transport, radiative transfer and kinetic equations is established and solved, considering (i) a two dimensional geometry, and (ii) a simple monomolecular photoreaction , where the species A and B are in competition for absorbing incident photons. The model is expressed using classical dimensionless numbers, such as the Damköhler I and II numbers, the absorbance and the competitive absorption factor. The results show how and why, when competitive absorption exists, the occurrence of diffusion limitations ( DaII>1) can severely impact the conversion of the photochemical reaction and the photonic efficiency. Consequently, a diagram is proposed as a practical tool for selecting operating conditions subsequently avoiding these limitations. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-22T04:58:33.537006-05:
      DOI: 10.1002/aic.14718
       
  • Analysis and Optimization of Pressure Retarded Osmosis for Power
           Generation
    • Authors: Mingheng Li
      Pages: n/a - n/a
      Abstract: This work focuses on model‐based analysis and optimization of pressure retarded osmosis (PRO) for power generation. The effects of membrane properties (hydraulic permeability, mass transfer characteristics), design conditions (inlet osmotic pressures, inlet flows and membrane area) and operating condition (applied pressure) on power density and efficiency are systematically investigated. A dimensionless design parameter , originally developed in analysis and optimization of reverse osmosis, is used to quantify the effect of dilution in draw solution as water permeates through membrane. An optimization method is developed to maximize PRO performance. It is shown that dilution and concentration polarization significantly reduce the maximum power density, and the optimal ΔP shifts away from Δπ0/2 Moreover, power density and efficiency follow opposite trends when varying process conditions including draw solution flow rate and membrane area. Enhancing membrane properties is crucial to improve the economic feasibility of PRO. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-22T03:31:04.244934-05:
      DOI: 10.1002/aic.14715
       
  • Progression of Wet Granulation in a Twin Screw Extruder Comparing Two
           Binder Delivery Methods
    • Authors: H. Li; M.R. Thompson, K. P. O'Donnell
      Pages: n/a - n/a
      Abstract: The two available wetting methods for twin screw granulation, namely foam delivery and liquid injection, were studied in detail by examining granule development along the screws as powder formulation and screw design were varied. Granulation profiles were determined by particle size analysis of samples along the screws collected using the “screw pullout” technique. Analysis of the particle size and porosity of produced granules revealed only minor differences between the two methods of wetting despite the larger dropsize of liquid injection compared to foam delivery. Excipients like microcrystalline cellulose or hydroxypropyl methyl cellulose with poor spreading properties, quantified by their specific penetration time and nucleation ratio, made the differences more apparent. The general similarities in granulation independent of wetting method implied that binder dispersion in an extruder was dominated by mechanical dispersion. Screw design (i.e. location of kneading block) had the dominant effect on the granulation process in this study. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-20T01:17:43.309288-05:
      DOI: 10.1002/aic.14717
       
  • Engineering Biomass into Formaldehyde‐free Phenolic Resin for
           Composite Materials
    • Authors: Yongsheng Zhang; Zhongshun Yuan, Chunbao (Charles) Xu
      Pages: n/a - n/a
      Abstract: The use of formaldehyde to prepare phenol‐formaldehyde (PF) resins is one of the primary challenges for the world‐wide PF industry with respect to both sustainability and human health. This study reports a novel one‐pot synthesis process for phenol‐5‐Hydroxymethylfurfural (PHMF) resin as a formaldehyde‐free phenolic resin using phenol and glucose, and the curing of the phenolic resin with a green curing agent organosolv lignin (OL) or Kraft lignin (KL). Evidenced by 13C NMR, the curing mechanism involves alkylation reaction between the hydoxyalkyl groups of lignin and the ortho‐ and para‐ carbon of PHMF phenolic hydroxyl group. The curing kinetics was studied using differential scanning calorimetry (DSC) and the kinetic parameters were obtained. The OL/KL cured PHMF resins were tested in terms of thermal stability, and mechanical properties for their applications in fiberglass reinforced composite materials. The results obtained demonstrated that OL/KL can be promising curing agents for the PHMF resins. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-20T00:45:21.837433-05:
      DOI: 10.1002/aic.14716
       
  • Towards More Cost‐Effective and Greener Chemicals Production from
           Shale Gas by Integrating with Bioethanol Dehydration: Novel Process Design
           and simulation‐based Optimization
    • Authors: Chang He; Fengqi You
      Pages: n/a - n/a
      Abstract: This paper presents a novel process design for a more cost‐effective, greener process for making chemicals from shale gas and bioethanol. The oxidative coupling of methane (OCM) and co‐cracking technologies are considered for converting methane and light natural gas liquids (NGLs), into value‐added chemicals. Overall, the process includes four process areas: gas treatment, gas to chemicals, methane‐to‐ethylene, and bioethanol‐to‐ethylene. We develop a simulation‐optimization method based on the NSGA‐II algorithm for the life cycle optimization (LCO) of the process modelled in the Aspen HYSYS. An energy integration model is also fluidly nested using the mixed‐integer linear programming. The results show that for a “good choice” optimal design, the minimum ethylene selling price is $655.1/ton and the unit global‐warming potential of ethylene is 0.030 kg CO2‐eq/kg in the low carbon shale gas scenario, and $877.2/ton and 0.360 kg CO2‐eq/kg in the high carbon shale gas scenario. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-15T10:13:12.540377-05:
      DOI: 10.1002/aic.14713
       
  • Synthesis of C‐H‐O Symbiosis Networks
    • Authors: Mohamed M. B. Noureldin; Mahmoud M. El‐Halwagi
      Pages: n/a - n/a
      Abstract: This paper introduces the concept of synthesizing carbon, hydrogen, and oxygen (C‐H‐O) SYmbiosis Networks (CHOSYNs) for the design of eco‐industrial parks (EIPs). Within a CHOSYN, compounds containing C‐H‐O are exchanged, converted, separated, mixed, and allocated. The use of C‐H‐O as the basis for integration creates numerous opportunities for synergism because C, H, and O are the primary building blocks for many industrial compounds that can be exchanged and integrated. A particularly attractive feature of the CHOSYN framework is its ability to use atomic‐based targets to establish benchmarks for the design of macroscopic systems involving multiple processes. Several structural representations, benchmarking, and optimization formulations are developed to embed potential CHOSYN configurations of interest and to synthesize cost‐effective networks. A case study with several scenarios is solved to demonstrate the new concept and tools. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-15T10:12:51.415866-05:
      DOI: 10.1002/aic.14714
       
  • A Unified Theoretical Model for Breakup of Bubbles and Droplets in
           Turbulent Flows
    • Authors: Chutian Xing; Tiefeng Wang, Kunyu Guo, Jinfu Wang
      Pages: n/a - n/a
      Abstract: Pressure has a significant effect on bubble breakup, and bubbles and droplets have very different breakup behaviors. This work aimed to propose a unified breakup model for both bubbles and droplets including the effect of pressure. A mechanism analysis was made on the internal flow through the bubble/droplet neck in the breakup process, and a mathematical model was obtained based on the Young–Laplace and Bernoulli equations. The internal flow behavior strongly depended on the pressure or gas density, and based on this mechanism a unified breakup model was proposed for both bubbles and droplets. For the first time, this unified breakup model gave good predictions of both the effect of pressure or gas density on the bubble breakup rate and the different daughter size distributions of bubbles and droplets. The effect of the mother bubble/droplet diameter, turbulent energy dissipation rate and surface tension on the breakup rate and daughter bubble/droplet size distribution were discussed. This bubble breakup model can be further used in a population balance model (PBM) to study the effect of pressure on the bubble size distribution, and in a CFD‐PBM coupled model to study the hydrodynamic behaviors of a bubble column at elevated pressures. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-15T10:12:01.897265-05:
      DOI: 10.1002/aic.14709
       
  • Effects of Flow History on Oil Entrapment in Porous Media: An Experimental
           Study
    • Authors: Homa Khosravian; Vahid Joekar‐Niasar, Nima Shokri
      Pages: n/a - n/a
      Abstract: The effect of flow history on fluid phase entrapment during immiscible two‐phase flow in Hele‐Shaw cells packed with spherical and crushed glass beads is investigated. The wetting fluid is injected into an initially‐oil saturated cell at a well‐defined capillary number. It is observed that the size and shape of the trapped clusters strongly depend on the history of flooding such that less oil was trapped in the medium when the injecting capillary number gradually increased to the final maximum capillary number compared to the case when the injection was started and maintained constant at the maximum capillary number. In addition, a comprehensive series of experiments were conducted to delineate the effects of the capillary number on the phase entrapment. Contrary to previously published data, our experimental data reveals that the residual oil saturation depends on capillary number non‐monotonically. A physically based relationship to scale the capillary desaturation curve is proposed. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-15T10:11:43.560682-05:
      DOI: 10.1002/aic.14708
       
  • Fluidized‐bed CVD of unstacked double‐layer templated graphene
           and its application in supercapacitors
    • Authors: Gui‐Li Tian; Qiang Zhang, Meng‐Qiang Zhao, Hao‐Fan Wang, Cheng‐Meng Chen, Fei Wei
      Pages: n/a - n/a
      Abstract: Graphene is inclined to stack with each other that greatly hinders the full utilization of its intrinsic extraordinary properties. Introducing protuberant spacers is a straightforward strategy to avoid the stacking of graphene nanosheets, resulting in a novel unstacked double‐layer template graphene (DTG) structure. Herein, a family of layered double hydroxides (LDHs) were employed for the bulk chemical vapor deposition (CVD) of DTG in a fluidized‐bed reactor. A high specific surface area of 1554.2m2 g−1 and a large pore volume of 1.70cm3 g−1 were achieved. When employed as the electrode material for supercapacitors, the DTG afforded a specific capacitance of 65.5 F g−1 at a sweep rate of 5.0 mV s−1 and a capacitance retention of 77% when the sweep rate was increased to 500 mV s−1. Therefore, the DTG obtained via fluidized bed CVD is a promising electrode material for supercapacitor applications. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-12T03:10:39.495432-05:
      DOI: 10.1002/aic.14710
       
  • Multicomponent gas diffusion in non‐uniform tubes
    • Authors: Thomas Veltzke; Lars Kiewidt, Jorg Thöming
      Pages: n/a - n/a
      Abstract: In many technical processes gas multicomponent diffusion takes place in confinements that are rarely uniform in direction of their long axis (e.g., catalysts pores). Here we show that in conical tubes multicomponent diffusion is hindered. This effect increases with ratio of inlet to outlet cone radius Λ, indifferent of the orientation of the tube. Based on the Maxwell‐Stefan equations we developed a predictive analytical solution for ideal multicomponent diffusion in slightly tapered ducts. In Two Bulb Diffusion Experiments on a uniform tube the results of Duncan and Toor (1962) were reproduced. Comparison of model and experiment shows that the solution presented here provides a reliable quantitative prediction of the temporal change of H2, N2, and CO2‐concentration for both tube geometries, uniform and slightly conical. In the demonstrated case (Λ = 3.16) mass diffusion is 68% delayed. Thus, for gaseous diffusion in “real”, typically tapered pores the transport limitation is more serious than considered so far. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-12T03:10:22.574515-05:
      DOI: 10.1002/aic.14711
       
  • Optimal design and operations of water supply chain networks for shale gas
           production: MILFP model and algorithms for the water‐energy nexus
    • Authors: Jiyao Gao; Fengqi You
      Pages: n/a - n/a
      Abstract: The optimal design and operations of water supply chain networks for shale gas production is addressed. A mixed‐integer linear fractional programming (MILFP) model is developed with the objective to maximize profit per unit freshwater consumption, such that both economic performance and water‐use efficiency are optimized. The model simultaneously accounts for the design and operational decisions for freshwater source selection, multiple transportation modes, and water management options. Water management options include disposal, commercial centralized wastewater treatment (CWT), and onsite treatment (filtration, lime softening, thermal distillation). To globally optimize the resulting MILFP problem efficiently, three tailored solution algorithms are presented: a parametric approach, a reformulation‐linearization method, and a novel Branch‐and‐Bound & Charnes‐Cooper transformation method. The proposed models and algorithms are illustrated through two case studies based on Marcellus shale play, in which onsite treatment shows its superiority in improving freshwater conservancy, maintaining a stable water flow, and reducing transportation burden. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-12T02:57:40.621741-05:
      DOI: 10.1002/aic.14705
       
  • Bubble breakup with permanent obstruction in an asymmetric microfluidic
           T‐junction
    • Authors: Xiaoda Wang; Chunying Zhu, Taotao Fu, Youguang Ma
      Pages: n/a - n/a
      Abstract: Bubble breakup with permanent obstruction in an asymmetric microfluidic T‐junction is investigated experimentally. The breakup process of bubbles can be divided into three stages: squeezing, transition and pinch‐off stages. In the squeezing stage, the thinning of the bubble neck is mainly controlled by the velocity of the fluid flowing into the T‐junction, and the increase of the liquid viscosity can promote this process. In the transition stage, the minimum width of bubble neck decreases linearly with time. In the pinch‐off stage, the effect of the velocity of the fluid flowing into the T‐junction on the thinning of the bubble neck becomes weaker, and the increase of the liquid viscosity would delay this process. The evolution of the minimum width of the bubble neck with the remaining time before the breakup can be scaled by a power‐law relationship. The bubble length has little influence on the whole breakup process of bubbles. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-04T11:16:08.676803-05:
      DOI: 10.1002/aic.14704
       
  • Steady state behavior of liquid fuel hydrazine decomposition in packed bed
    • Authors: Baolin Hou; Xiaodong Wang, Tao Li, Tao Zhang
      Pages: n/a - n/a
      Abstract: A general theoretical model is presented to analyze the steady‐state decomposition process of liquid monopropellants in packed beds for thruster systems. Additionally, an experiment studying the decomposition of liquid hydrazine in a packed bed is employed to validate this model. The liquid droplet evaporation rate is determined through calculating the gas‐liquid mass transfer for the mixture temperatures lower than the liquid propellant boiling point and solving the gas‐liquid or liquid‐solid heat transfer equations at the temperature exceeding the boiling point. The process of liquid propellant decomposition in packed beds are simulated based on the Naive‐Stokes equation for the mixture model integrated with the developed liquid evaporation rate, in which both the heterogeneous catalytic reaction coupled with the diffusion of reactants in the pore of catalyst, and the homogenous decomposition reactions are considered. The calculated results for the axial distribution of the temperature are in good agreement with the experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-04T11:01:36.213364-05:
      DOI: 10.1002/aic.14703
       
  • Experimental study on oscillating feedback micromixer for miscible liquids
           using the coanda effect
    • Authors: Cong Xu; Yifeng Chu
      Pages: n/a - n/a
      Abstract: An oscillating feedback micromixer with no moving parts comprises an inlet channel, a diverging mixing chamber, a splitter, two feedback channels, and an outlet channel. Using the Coanda effect, two liquids are passively mixed in an oscillating feedback micromixer. Three oscillating feedback micromixers were experimentally investigated using two miscible liquids. The first had asymmetric feedback channels and a splitter, the second had symmetric feedback channels and a splitter, and the third had symmetric feedback channels and no splitter. Three chaotic mixing modes — vortex mixing, internal recirculation mixing, and oscillating mixing — were observed with increasing Reynolds numbers. The asymmetric oscillating feedback micromixer was determined to have the best mixing performance among the three micromixers. The splitter and asymmetric feedback channels can facilitate internal recirculation through feedback channels and fluidic oscillation, thereby enhancing the mixing efficiency. A completed mixing was achieved in the asymmetric micromixer. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-04T11:01:34.713062-05:
      DOI: 10.1002/aic.14702
       
  • Synthesis of butyl acrylate in a fixed‐bed adsorptive reactor over
           amberlyst 15
    • Authors: Dânia S.M. Constantino; Carla S.M. Pereira, Rui P. V. Faria, Alexandre F. P. Ferreira, José M. Loureiro, Alírio E. Rodrigues
      Pages: n/a - n/a
      Abstract: The butyl acrylate (BAc) synthesis from the esterification reaction of acrylic acid (AAc) with 1‐butanol in a fixed‐bed adsorptive reactor packed with Amberlyst 15 ion exchange resin was evaluated. Adsorption experiments were carried out with non‐reactive pairs at two temperatures (323 and 363 K). The experimental results were used to obtain multicomponent adsorption equilibrium isotherms of Langmuir type. Reactive adsorption experiments using different feed molar ratios and flow rates were performed, at 363 K, and used to validate a mathematical model developed to describe the dynamic behaviour of the fixed‐bed adsorptive reactor for the BAc synthesis. Due to the simultaneous reaction and separation steps, it was possible to obtain a BAc maximum concentration 38% higher than the equilibrium concentration (for an equimolar reactants ratio solution as feed at a flow rate of 0.9 mL.min‐1 and 363 K) showing that sorption enhanced reaction technologies are very promising for BAc synthesis. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-02T11:02:43.798377-05:
      DOI: 10.1002/aic.14701
       
  • Material properties and operating configurations of membrane reactors for
           propane dehydrogenation
    • Authors: Seung‐Won Choi; Christopher W. Jones, Sankar Nair, David S. Sholl, Jason S. Moore, Yujun Liu, Ravindra S. Dixit, John G. Pendergast
      Pages: n/a - n/a
      Abstract: A modeling‐based approach is presented to understand physically realistic and technologically interesting material properties and operating configurations of packed‐bed membrane reactors (PBMRs) for propane dehydrogenation (PDH). PBMRs composed of microporous or mesoporous membranes combined with a PDH catalyst are considered. The influence of reaction and membrane transport parameters, as well as operating parameters such as sweep flow and catalyst placement, are investigated to determine desired ‘operating windows' for isothermal and non‐isothermal operation. Higher Damköhler (Da) and lower Péclet (Pe) numbers are generally helpful, but are much more beneficial with highly H2‐selective membranes rather than higher‐flux, lower‐selectivity membranes. H2‐selective membranes show a plateau region of conversion that can be overcome by a large sweep flow or countercurrent operation. The latter shows a complex trade‐off between kinetics and permeation, and is effective only in a limited window. H2‐selective PBMRs will greatly benefit from the fabrication of thin (∼1μm or less) membranes. This article is protected by copyright. All rights reserved.
      PubDate: 2014-12-02T08:04:28.147766-05:
      DOI: 10.1002/aic.14700
       
  • Particle‐scale modeling of coal devolatilization behaviors for coal
           pyrolysis in thermal plasma reactors
    • Authors: Binhang Yan; Yan Cheng, Yi Cheng
      Pages: n/a - n/a
      Abstract: A generalized heat transfer and devolatilization model coupled with the thermal balance between the heating gas and particles was established to predict the complex coal pyrolysis behaviors in the practical plasma reactors. It was proved that this model could well describe the coal devolatilization behaviors in both the pilot‐scale and lab‐scale plasma reactors since the mechanisms of coal chemistry and particle‐scale physics were incorporated. The achieved understanding on the reactor energy balance demonstrated that the heat recovery of the quenching process was crucial to the thermal efficiency and economic benefit of the overall project. The in‐depth discussion of the influences of coal feed rate and particle size on the reactor performance revealed the dominant roles and presented the optimal values of these two factors. In particular, the simulation results of several coals could help to provide a simple, quick method of coal type selection for industrial plasma processes. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-25T10:59:00.653138-05:
      DOI: 10.1002/aic.14698
       
  • Transport processes at single droplets in micellar liquid/liquid systems
    • Authors: Niklas Paul; Sebastian Schön, Regine von Klitzing, Matthias Kraume
      Pages: n/a - n/a
      Abstract: In many industrial applications the knowledge of the occurring transport processes in liquid/liquid systems is of great interest to design a multiphase reactor or an extraction column, for instance. All transport processes in liquid/liquid systems are governed by the interface. In some processes surfactants are needed. Surfactants change many interfacial properties which affect the transport processes. In this work the influence of high surfactant concentrations (micellar systems) on transport processes is regarded. To understand the occurring reduction of the drop rise velocity and of mass transfer rates experimental investigations of the occurring interfacial phenomena are carried out. Therefore, interfacial tension measurements as well as colloidal probe atomic force measurements of liquid/liquid systems were conducted. It was proved that for high nonionic surfactant concentrations a change of the phase behavior must be taken into consideration to describe transport processes in micellar liquid/liquid systems. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-25T10:56:04.830817-05:
      DOI: 10.1002/aic.14699
       
  • A new mechanistic model to predict gas‐liquid interface shape of
           gas‐liquid flow through pipes with low liquid loading
    • Authors: A. Banafi; M.R. Talaei
      Pages: n/a - n/a
      Abstract: The present paper is concerned with devising a new mechanistic method to predict gas‐liquid interface shape in horizontal pipes. An experiment was conducted to find the pressure gradients of air‐water flow through a 1 inch pipe diameter. Comparing results of model with some experimental data available in the literature demonstrates that the model provides quite better predictions than existed models do. This model also predicts flow regime transition from stratified to annular flow better than ARS (Apparent Rough Surface) and MARS (Modified Apparent Rough Surface) models for both 1 and 2 inch pipe diameters. The model also leads to reliable predictions of wetted wall fraction experimental data. Although one parameter of new model was evaluated based on air‐water flow pressure loss experimental data for 1 inch pipe, it was considerably successful to predict pressure drop, liquid holdup, stratified‐annular transition and wetted wall fraction for other gas‐liquid systems and pipe diameters. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-20T00:09:43.93212-05:0
      DOI: 10.1002/aic.14696
       
  • A novel approach to determine wet restitution coefficients through a
           unified correlation and energy analysis
    • Authors: Vinayak S. Sutkar; Niels G. Deen, Johan T. Padding, Vitalij Salikov, Britta Crüger, Sergiy Antonyuk, Stefan Heinrich, J.A.M. Kuipers
      Pages: n/a - n/a
      Abstract: Wet particle interactions are observed in many applications e.g. pharmaceutical, food, agricultural, polymerization, agglomeration and coating, in which an accurate evaluation of the wet restitution coefficient (ewet) is crucial to understand the particle flowability, operating conditions and product size distribution. In this work, experiments were performed to measure the wet restitution coefficient by impacting a spherical particle on a stationary plate covered with a thin liquid layer of water or glycerol solution. Furthermore, novel approaches for estimation of ewet were developed using dimensional analysis (using the Buckingham π theorem and regression analysis) in combination with energy budget analysis. In the correlation development, the dominant physical properties of solid and liquid, particle impact velocity and liquid layer thickness are grouped into well‐known dimensionless numbers viz. Reynolds, Weber and Stokes. Whereas in the energy analysis, the energy dissipation rates were determined for five distinct collision phases i.e. dipping, dry collision, un‐dipping, formation and breakage of the liquid bridge, and added mass. The efficacy of the developed approaches was analysed by comparing obtained results with experiments and an elastohydrodynamic model, and a modified elastohydrodynamic model. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T22:35:07.223628-05:
      DOI: 10.1002/aic.14693
       
  • PEPT study of particle cycle and residence time distributions in a Wurster
           fluid bed
    • Authors: Liang Li; Anders Rasmuson, Andy Ingram, Mats Johansson, Johan Remmelgas, Christian von Corswant, Staffan Folestad
      Pages: n/a - n/a
      Abstract: Particle cycle and residence time distributions are critical factors in determining the coating quality in the Wurster process. In this work, PEPT experiments are performed to determine the cycle and residence times of particles in different regions of a Wurster fluid bed. The results show that particles tend to recirculate in and sneak out below from the Wurster tube. The experiments also show that a larger batch size leads to a shorter cycle time and a narrower cycle time distribution. It is possible to avoid recirculations and obtain a shorter cycle time and a narrower cycle time distribution by selecting the operating conditions appropriately or via equipment design. Experiments using binary mixtures of particles with a diameter ratio of 1.5 show that large particles have a longer cycle time than small particles and that the cycle time is shorter for mixtures with approximately equal amounts of small and large particles. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T10:33:42.763449-05:
      DOI: 10.1002/aic.14692
       
  • Blend uniformity and powder phenomena inside the continuous tumble mixer
           using DEM simulations
    • Authors: Miguel Florian‐Algarin; Rafael Méndez
      Pages: n/a - n/a
      Abstract: Powder mixing is an essential operation in pharmaceutical, food, and petrochemical industries. Pharmaceutical companies have been working in the implementation of continuous processes as an alternative to the batch process using the Food and Drug Administration (FDA) Process Analytical Technology (PAT) initiative. The main goal of this study was to understand the mixing phenomena inside the continuous tumble mixer and monitor blend uniformity using Discrete Element Method (DEM). Results demonstrated that the main mixing mechanism is convection similar to the common tumbling mixers. This mechanism is driven by the bulk flow of the particles, due to the mixer rotation. The simulations' results, demonstrated that the cohesion reduces the concentration variability due to the higher hold‐up, particle interactions and mean residence time. The blend uniformity at the exit of the system was measured and a relationship between relative standard distribution (RSD), cohesion, and the collision frequency was found. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-18T10:33:26.89043-05:0
      DOI: 10.1002/aic.14694
       
  • A fundamental model for valve tray vapor cross‐flow channeling
           calculation
    • Authors: Jun Wang; Yixin Leng, Hui Shao, Weimin Li, Bin Xue, Chunxiang Huang, Ping Yang, Qian Tan, Tianxing Chen
      Pages: n/a - n/a
      Abstract: An accurate prediction of tray hydraulics is very important for large diameter trays design, and vapor cross‐flow channeling is one of the key points that affect the hydraulics calculation. Therefore, in this article, a theoretical analysis was first conducted to reveal that the energy of gas‐liquid on the tray was closely related to its flow state. Then, a model was obtained on the basis of the principle of the lowest energy, which can be used to calculate vapor cross‐flow channeling. The model shows that the ratio of dry tray pressure drop to liquid height on a tray determines the gas distribution on the tray. Finally, the model was tested by comparisons with experimental results available in reference. The agreements are good. Furthermore, the effects of liquid load and fractional hole area on vapor cross‐flow channeling were studied. The results are consistent with the field experience summarized in literatures. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:38:08.64152-05:0
      DOI: 10.1002/aic.14691
       
  • 1‐Dimensional productivity assessment for on‐field methane
           hydrate production using co2/n2 mixture gas
    • Authors: Dong‐Yeun Koh; Yun‐Ho Ahn, Hyery Kang, Seongmin Park, Joo Yong Lee, Se‐Joon Kim, Jaehyoung Lee, Huen Lee
      Pages: n/a - n/a
      Abstract: The direct recovery of methane from methane hydrate bearing sediments is demonstrated, where a gaseous mixture of (CO2+N2) is used to trigger a replacement reaction in complex phase surroundings. A 1D high‐pressure reactor (8 m) was designed to test the actual aspects of the replacement reaction occurring in natural gas hydrate reservoir conditions. Natural Gas Hydrate (NGH) can be converted into CO2 hydrate by a ‘replacement mechanism,’ which serves double duty as a means of both sustainable energy source extraction and greenhouse gas sequestration. The replacement efficiency controlling totally recovered CH4 amount is inversely proportional to (CO2+N2) injection rate directly affecting contact time. A qualitative analysis on compositional profiles at each port reveals that the length more than 5.6 m is required to show noticeable recovery rate for NGH production. The present outcomes are expected to establish the optimized key process variables for near future field production tests. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-17T06:37:43.809754-05:
      DOI: 10.1002/aic.14687
       
  • Proposal and Verification of a Kinetic Mechanism Model for NOx Removal
           with Hydrazine Hydrate
    • Authors: L. Hong; L. J. Yin, D. Z. Chen, D. Wang
      Pages: n/a - n/a
      Abstract: In this study, a relatively precise kinetic mechanism of NOx reduction using N2H4·H2O in a selective non‐catalytic reduction (SNCR) process was proposed and verified by experiment. The dominant radicals and reactions were confirmed, and the proper ranges of key parameters were determined through sensitivity analysis. Both experiment and simulation results show that the effective temperatures exhibit a bimodal distribution with the optimum temperatures being approximately 893K and 1248K and the lower temperature window falling in the range of 848 to 973K. The optimum residence time of the reaction was 0.2~0.35s under the research conditions, and a longer residence time would lead to the re‐generation of NOx. The normalized stoichiometric ratio (NSR) of 3.0 corresponded to the lowest temperature window, and a higher NSR value would make the temperature window shift to a higher temperature range. This kinetic mechanism model for the N2H4·H2Obased De‐NOx process will serve its precise application. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T03:34:12.489072-05:
      DOI: 10.1002/aic.14688
       
  • Hydrogen and carbon dioxide adsorption with tetra‐n‐butyl
           ammonium semi‐clathrate hydrates for gas separations
    • Authors: Hiroyuki Komatsu; Masaki Ota, Yoshiyuki Sato, Masaru Watanabe, Richard L. Smith
      Pages: n/a - n/a
      Abstract: Gas adsorption rates of H2, CO2 and H2‐CO2 gas mixture (H2/CO2 = 3.4) with tetra‐n‐butyl ammonium salt (bromide, chloride and fluoride) semi‐clathrate hydrate particles were measured at 269 K to assess their properties for gas separation. Equilibrium gas occupancies in the S‐cages of the particles were in order of (high to low) for HS‐I, TS‐I and SCS‐I structures with the maximum fractional occupancy by CO2 being about 40 %. The CO2 diffusion rate depended on the anion size of the salt, which is attributed to distortion of the S‐cage that is close to the molecular size of CO2. Simulations of semi‐clathrate hydrate particles with theory showed that H2/CO2 selectivities could be as high as 36 (3.0 mol% TBAF) and that selectivities for an ideal membrane (3.3 mol% TBAF) could be greater than 100 (269 K, 0.3 – 4.5 MPa). Semi‐clathrate hydrates have wide application as separation media for gas mixtures. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T03:33:09.598354-05:
      DOI: 10.1002/aic.14689
       
  • Robust algorithms for the solution of the ideal adsorbed solution theory
           equations
    • Authors: Enzo Mangano; Daniel Friedrich, Stefano Brandani
      Pages: n/a - n/a
      Abstract: The Ideal Adsorbed Solution (IAS) theory has been shown to predict reliably multicomponent adsorption for both gas and liquid systems. There is a lack of understanding of the conditions which guarantee convergence for various algorithms used to solve the IAS theory equations and inconsistencies are present in the reported computational effort required for the different approaches. The original nested loop and the FastIAS technique are revisited. The resulting system of equations is highly nonlinear but both methods are shown to be robust if appropriate choices are made for the starting values of the unknown variables. New initial conditions are proposed and the resulting algorithms are compared in a consistent manner with the main methods available to solve the IAS theory equations. The algorithms are extended for the first time to all non‐type I isotherms. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-15T00:50:52.275943-05:
      DOI: 10.1002/aic.14684
       
  • Economic model predictive control of nonlinear process systems using
           empirical models
    • Authors: Anas Alanqar; Matthew Ellis, Panagiotis D. Christofides
      Pages: n/a - n/a
      Abstract: Economic model predictive control (EMPC) is a feedback control technique that attempts to tightly integrate economic optimization and feedback control since it is a predictive control scheme that is formulated with an objective function representing the process economics. As its name implies, EMPC requires the availability of a dynamic model to compute its control actions and such a model may be obtained either through application of first‐principles or through system identification techniques. In industrial practice, it may be difficult in general to obtain an accurate first‐principles model of the process. Motivated by this, in the present work, Lyapunov‐based EMPC (LEMPC) is designed with a linear empirical model that allows for closed‐loop stability guarantees in the context of nonlinear chemical processes. Specifically, when the linear model provides a sufficient degree of accuracy in the region where time‐varying economically optimal operation is considered, conditions for closed‐loop stability under the LEMPC scheme based on the empirical model are derived. The LEMPC scheme is applied to a chemical process example to demonstrate its closed‐loop stability and performance properties as well as significant computational advantages. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:45:52.076998-05:
      DOI: 10.1002/aic.14683
       
  • A conceptual model for chemical product design
    • Authors: Fernando P Bernardo; Pedro M. Saraiva
      Pages: n/a - n/a
      Abstract: The fundamental principles of chemical product design and associated systematic tools, within a broad domain of chemical products including molecules, formulations and devices, are still under development. In this paper, we propose a simple and fundamental conceptual model that defines the chemical product design problem as the inversion of three central design functions: quality, property and process functions. The classic iterative cycles of product design problems may be envisioned as alternating between inversion and evaluation of these three functions, or in other words alternating between synthesis and analysis of solutions. On top of the proposed basic structure of the overall design problem, we then discuss the formulation of some subproblems as optimization problems and describe some useful solution tools. Three application examples are provided, including a more detailed case of formulation of a pharmaceutical ointment. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:45:37.22391-05:0
      DOI: 10.1002/aic.14681
       
  • Effect of dielectric packing materials on the decomposition of carbon
           dioxide using DBD microplasma reactor
    • Authors: Xiaofei Duan; Zongyuan Hu, Yanping Li, Baowei Wang
      Pages: n/a - n/a
      Abstract: Carbon dioxide (CO2) decomposition was carried out at a normal atmosphere and room temperature in dielectric barrier discharge (DBD) microplasma reactors to reduce CO2 emissions and convert CO2 into valuable chemical materials. The outlet gases, including CO2, CO, and O2, were analyzed with gas chromatography. The results indicated that the conversions of CO2 in dielectric material‐packed reactors were all higher than that in non‐packed reactors. Particle size, dielectric constant, particle morphology, and acid‐base properties of the dielectric materials (including quartz wool, quartz sand, γ‐Al2O3, MgO, and CaO) all affected the CO2 decomposition process. The conversion of CO2 and energy efficiency achieved the highest values of 41.9 % and 7.1 % in a CaO‐packed reactor for the higher dielectric constant and basicity of CaO. Quartz wool was also an excellent dielectric packing material because its fiber structure provided rigid sharp edges. This article is protected by copyright. All rights reserved.
      PubDate: 2014-11-14T04:31:50.865139-05:
      DOI: 10.1002/aic.14682
       
  • n‐Butane Carbonylation to n‐Pentanal Using a Cascade Reaction
           of Dehydrogenation and SILP‐Catalyzed Hydroformylation†
    • Authors: Simon Walter; Marco Haumann, Hanna Hahn, Robert Franke, Peter Wasserscheid
      Pages: n/a - n/a
      Abstract: A novel gas‐phase process has been developed that allows direct two‐step conversion of butane into pentanals with high activity and selectivity. The process consists of alkane dehydrogenation over a heterogeneous Cr/Al2O3 catalyst followed by direct gas‐phase hydroformylation using advanced supported ionic liquid phase (SILP) catalysis. The latter step uses rhodium complexes modified with the diphosphite ligands biphephos (BP) and benzopinacol (BzP) to convert the butane/butene mixture from the dehydrogenation step efficiently into aldehydes. The use of the BP ligand results in improved yields of linear pentanal because SILP systems with this ligand are active for both isomerization and hydroformylation. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-12T03:44:45.864729-05:
      DOI: 10.1002/aic.14676
       
  • A Systematic Methodology for Kinetic Modeling of Chemical Reactions
           applied to n‐Hexane Hydroisomerization
    • Authors: K. Toch; J.W. Thybaut, G.B. Marin
      Pages: n/a - n/a
      Abstract: Kinetic modeling provides chemical engineers with a unique opportunity to better understand reaction kinetics in general and the underlying chemistry in particular. How to systematically approach a modeling assignment in chemical reaction kinetics is typically less clear, especially for novices in the field. The proposed modeling methodology pursues an adequate compromise between statistical significance and physical meaning of the kinetic model and the corresponding parameters and typically results in models of an appropriate complexity. It comprises the following activities: (i) data analysis, aiming at qualitative information on the reaction mechanism and corresponding rate equations, (ii) model regression to quantify this information via optimal parameter values and (iii) validation of the statistical significance and physical meaning of the parameter estimates. This methodology is successfully applied to n‐hexane hydroisomerization on a bifunctional catalyst. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-12T03:20:54.758957-05:
      DOI: 10.1002/aic.14680
       
  • CO2 removal by single and mixed amines in a hollow‐fiber membrane
           module ‐ Investigation of contactor performance
    • Authors: Ion Iliuta; Francis Bougie, Maria C. Iliuta
      Pages: n/a - n/a
      Abstract: This work investigates CO2 removal by single and blended amines in a hollow‐fiber membrane contactor (HFMC) under gas‐filled and partially liquid‐filled membrane pores conditions via a two‐scale, non‐isothermal, steady‐state model accounting for CO2 diffusion in gas‐filled pores, CO2 and amines diffusion/reaction within liquid‐filled pores and CO2 and amines diffusion/reaction in liquid boundary layer. Model predictions were compared with CO2 absorption data under various experimental conditions. The model was used to analyze the effects of liquid and gas velocity, CO2 partial pressure, single (primary, secondary, tertiary and sterically hindered alkanolamines) and mixed amines solution type, membrane wetting and concurrent/countercurrent flow orientation on the HFMC performance. An insignificant difference between the absorption in cocurrent and countercurrent flow was observed in the present study. The membrane wetting decreases significantly the performance of hollow‐fiber membrane module. The non‐isothermal simulations reveal that the hollow‐fiber membrane module operation can be considered as nearly isothermal. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T03:28:52.156508-05:
      DOI: 10.1002/aic.14678
       
  • Application of polyethylenimine‐Impregnated solid adsorbents for
           direct capture of low‐concentration CO2
    • Authors: Jitong Wang; Mei Wang, Wencheng Li, Wenming Qiao, Donghui Long, Licheng Ling
      Pages: n/a - n/a
      Abstract: A systematic study of CO2 capture on the amine‐impregnated solid adsorbents is carried out at CO2 concentrations in the range of 400‐5000 ppm, relating to the direct CO2 capture from atmospheric air. The commercially available polymethacrylate‐based HP2MGL and polyethylenimine are screened to be the suitable support and amine respectively for preparation of the adsorbent. The adsorbents exhibit an excellent saturation adsorption capacity of 1.96 mmol/g for 400 ppm CO2 and 2.13 mmol/g for 5000 ppm CO2. Moisture plays a promoting effect on CO2 adsorption but depends on the relative humidity. The presence of O2 would lead to the decrease of adsorption capacity, but do not affect the cyclic performance. The diffusion additive is efficient to improve the adsorption capacity and cyclic performance. Moreover, the adsorbents can be easily regenerated under a mild temperature. This study may have a positive impact on the design of high‐performance adsorbents for CO2 capture from ambient air. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T03:27:12.426087-05:
      DOI: 10.1002/aic.14679
       
  • Pyrolysis of Heavy Oil in the Presence of Supercritical Water: The
           Reaction Kinetics in Different Phases
    • Authors: Xue‐Cai Tan; Qing‐Kun Liu, Dao‐Qi Zhu, Pei‐Qing Yuan, Zhen‐Min Cheng, Wei‐Kang Yuan
      Pages: n/a - n/a
      Abstract: In the presence of supercritical water (SCW) and N2, the pyrolysis of heavy oil was investigated to distinguish the difference in the reaction kinetics between the upgrading in the SCW and oil phases. The pyrolysis in the SCW phase is faster than that in the oil phase, but the reaction in whichever phase is retarded by vigorous stirring. The pyrolysis can be preferably described by a four‐lump kinetic model consisting of the condensation of maltenes and asphaltenes in series. In the SCW phase, highly dispersed asphaltenes are isolated by water clusters from maltenes dissolved in SCW surroundings, by which the condensation of asphaltenes is drastically accelerated. Benefited from excellent mass transfer environments in SCW, the condensation of maltenes is promoted simultaneously. The introduction of SCW into the pyrolysis of heavy oil results in an effectively increased upgrading efficiency, but its influence on the properties of equilibrium liquid products is minor. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-11T02:47:42.114472-05:
      DOI: 10.1002/aic.14677
       
  • Analysis of Solar‐Driven Gasification of Biochar Trickling through
           an Interconnected Porous Structure
    • Authors: Michael Kruesi; Zoran R. Jovanovic, Andreas Haselbacher, Aldo Steinfeld
      Pages: n/a - n/a
      Abstract: The efficient transfer of high‐temperature solar heat to the reaction site is crucial for the yield and selectivity of the solar‐driven gasification of biomass. This work investigates the performance of a gas‐solid trickle‐bed reactor constructed from a high thermal conductivity porous ceramic packing. Beech char particles were used as the model feedstock. A two‐dimensional finite‐volume model coupling chemical reaction with conduction, convection, and radiation of heat within the packing was developed and tested against measured temperatures and gasification rates. The sensitivity of the gasification rate and reactor temperatures to variations of the packing's pore diameter, porosity, thermal conductivity, and particle loading was numerically studied. A numerical comparison with a moving bed projected a more uniform temperature distribution and higher gasification rates due to the increased heat transfer via combined radiation and conduction through the trickle bed. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-07T09:35:45.419313-05:
      DOI: 10.1002/aic.14672
       
  • Analysis of mass transfer in a corotating disks catalytic reactor
    • Authors: C.T. Gonzalez‐Hidalgo; J. Herrero, D. Puigjaner
      Pages: n/a - n/a
      Abstract: We analyze the flow and mass transfer in a discontinuous reactor configuration consisting of a pair of corotating enclosed disks with a chemical reaction taking place at the disk surfaces. The calculated mass transfer efficiencies do not follow the expected Sh = Sh(Re,Sc) dependence because the overall mass transfer process is not boundary–layer controlled, especially at high Schmidt numbers. It has been found in all of the cases investigated that despite the fact that the reactant concentration is continuously dropping with time its spatial distribution, relative to the volume–averaged value, becomes stationary after a short initial transient. This result implies that the mass transfer efficiency in the discontinuous reactor also becomes stationary and the resulting time–independent value, Sh∞, obtained either directly from calculation or from the fit of the collected results, provides a fairly good estimate of the reactor operation time needed to achieve the target reactant conversion. © 2014 American Institute of Chemical Engineers AIChE J, 2014
      PubDate: 2014-11-07T05:44:10.467164-05:
      DOI: 10.1002/aic.14668
       
 
 
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