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  Subjects -> ENGINEERING (Total: 2118 journals)
    - CHEMICAL ENGINEERING (179 journals)
    - CIVIL ENGINEERING (159 journals)
    - ELECTRICAL ENGINEERING (89 journals)
    - ENGINEERING (1163 journals)
    - ENGINEERING MECHANICS AND MATERIALS (341 journals)
    - HYDRAULIC ENGINEERING (54 journals)
    - INDUSTRIAL ENGINEERING (54 journals)
    - MECHANICAL ENGINEERING (79 journals)

ENGINEERING (1163 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: 3)
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: 6)
Bubble Science, Engineering & Technology     Hybrid Journal  
Bulletin of Canadian Petroleum Geology     Full-text available via subscription   (Followers: 2)
Bulletin of Engineering Geology and the Environment     Hybrid Journal   (Followers: 4)
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: 9)
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: 6)
Coal Science and Technology     Full-text available via subscription   (Followers: 4)
Coastal Engineering     Hybrid Journal   (Followers: 9)
Coastal Engineering Journal     Hybrid Journal   (Followers: 2)
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: 13)
Composite Interfaces     Hybrid Journal   (Followers: 3)
Composite Structures     Hybrid Journal   (Followers: 74)
Composites Part A : Applied Science and Manufacturing     Hybrid Journal   (Followers: 55)
Composites Part B : Engineering     Hybrid Journal   (Followers: 79)
Composites Science and Technology     Hybrid Journal   (Followers: 56)
Comptes Rendus Mécanique     Full-text available via subscription  
Computation     Open Access   (Followers: 1)
Computational Geosciences     Hybrid Journal   (Followers: 12)
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: 7)
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: 31)
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: 1.098]   [H-I: 104]   [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  [1608 journals]
  • Efficient tuning of microstructure and surface chemistry of nanocarbon
           catalysts for ethylbenzene direct dehydrogenation
    • Authors: Zhongkui Zhao; Yitao Dai, Guifang Ge, Guiru Wang
      Abstract: A facile and scalable approach to efficiently tune microstructure and surface chemical properties of N‐doped carbocatalysts through the controlled glucose hydrothermal treatment with diverse parameters and subsequent pyrolysis of pretreated carbonaceous materials with melamine (GHT‐PCM) was presented. Various characterization techniques including HRTEM, BET, XRD, XPS, Raman and FT‐IR were employed to investigate the effect of prior GHT on the microstructure and surface chemical properties of N‐doped carbocatalysts, as well as to reveal the relationship between catalyst nature and catalytic performance in oxidant‐ and steam‐free direct dehydrogenation of ethylbenzene (DDH) for styrene production. It was found that the GHT process and its conditions significantly affect microstructure and surface chemical properties of the N‐doped carbocatalysts, which subsequently influences their catalytic performance in DDH reaction dramatically. Interestingly, the prior GHT can remove the carbon nitride layer formed on parent nanocarbon in the process of melamine pyrolysis, produce structural defects and tune surface element component, through the “detonation” of polysaccharide coating on nanocarbon. The as‐prepared N‐doped CNT (M‐Glu‐CNT) by the established GHT‐PCM approach in this work demonstrates higher catalytic performance (4.6 mmol g−1 h−1 styrene rate with 98% selectivity) to the common N‐doped CNT (M‐CNT, 3.4 mmol g−1 h−1 styrene rate with 98.2% selectivity) as well as to pristine CNT (2.8 mmol g−1 h−1 styrene rate with 96.8% selectivity), mainly ascribed to increased structural defects, enriched surface ketonic C=O groups, and improved basic properties from N‐doping on the M‐Glu‐CNT, those strongly depend on GHT conditions. The excellent catalytic performance of the developed M‐Glu‐CNT catalyst endows it with great potential for future clean production of styrene via oxidant‐ and steam‐free conditions. Moreover, the directed GHT‐PCM strategy can be extended to the other N‐doped carbonaceous materials with enhanced catalytic performance in diverse reactions by tuning their microstructure and surface chemistry. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T17:40:02.013477-05:
      DOI: 10.1002/aic.14853
       
  • Control of spatially distributed processes with unknown
           transport‐reaction parameters via two layer system adaptations
    • Authors: Davood Babaei Pourkargar; Antonios Armaou
      Abstract: We consider the control problem of dissipative distributed parameter systems described by semilinear parabolic partial differential equations with unknown parameters and its application to transportreaction chemical processes. The infinite dimensional modal representation of such systems can be partitioned into finite dimensional slow and infinite dimensional fast and stable subsystems. A combination of a model order reduction approach and a Lyapunov‐based adaptive control technique is used to address the control issues in the presence of unknown parameters of the system. Galerkin's method is used to reduce the infinite dimensional description of the system where we apply adaptive proper orthogonal decomposition (APOD) to initiate and recursively revise the set of empirical basis functions needed in Galerkin's method to construct switching reduced order models. The effectiveness of the proposed APOD‐based adaptive control approach is successfully illustrated on temperature regulation in a catalytic chemical reactor in the presence of unknown transport and reaction parameters. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T17:39:37.56325-05:0
      DOI: 10.1002/aic.14852
       
  • Effect of ionic strength on bubble coalescence in inorganic salt and
           seawater solutions
    • Authors: J.M. Sovechles; K.E. Waters
      Abstract: Bubble size is of fundamental importance in the flotation process, as it provides the surface area for particle collection. Typically weak surfactants (frothers) are added to process water to reduce bubble coalescence. Certain inorganic electrolytes, which occur naturally in some flotation process water, have been shown to mimic the role of frothers. The concentration at which bubble coalescence is inhibited, the critical coalescence concentration, was determined in a 5.5 L mechanical flotation cell for a series of coalescence inhibiting inorganic salts. To mimic some industrial flotation process water, a synthetic sea salt solution was also tested. It was found that when the multi‐component sea salt solution was broken down into its constituent parts, the addition of the ionic strength of each ion correlated well with the overall ionic strength curve of all the salts tested. The critical coalescence ionic strength ranged from 0.22 to 0.35, with sea salt being 0.26. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T17:39:16.488239-05:
      DOI: 10.1002/aic.14851
       
  • A multi‐objective optimization framework for design of integrated
           biorefineries under uncertainty
    • Authors: A. Geraili; J.A. Romagnoli
      Abstract: A systematic approach for development of a reliable optimization framework to address the optimal design of integrated biorefineries in the face of uncertainty is presented. In the current formulation, we apply a distributed strategy which is composed of different layers including strategic optimization, risk management, detailed mechanistic modeling and operational level optimization. In the strategic model, a multi‐objective stochastic optimization approach is utilized to incorporate the tradeoffs between the cost and the financial risk. Then, Aspen Plus models are built to provide detailed simulation of biorefineries. In the final layer, an evolutionary algorithm is employed to optimize the operating condition. To demonstrate the effectiveness of the framework, a hypothetical case study referring to a multi‐product lignocellulosic biorefinery is utilized. The numerical results reveal the efficacy of the proposed approach; it provides decision makers with a quantitative analysis to determine the optimum capacity plan and operating conditions of the biorefinery. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T17:32:09.313775-05:
      DOI: 10.1002/aic.14849
       
  • Thermal conductivity of nanofluids: Effect of brownian motion of
           nanoparticles
    • Authors: Rachid Chebbi
      Abstract: We discuss the model of Xuan et al. (2003) for the thermal conductivity of nanofluids in which Brownian motion effect is added to the classical Maxwell's equation. The model is revised. Also a different model is given and found to yield the same expression for the effective thermal conductivity after amending Xuan et al.'s model. The findings do not support the claim that Brownian motion of nanoparticles has a significant impact on thermal conductivity. Also nanoparticles clustering is found to have a very minor effect on the effective thermal conductivity of nanofluids; however the analysis may not be appropriate to draw conclusions about the impact of clustering. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-22T17:31:46.779486-05:
      DOI: 10.1002/aic.14847
       
  • A letter to the editor
    • Authors: Yimin Xuan
      PubDate: 2015-04-22T17:31:27.819205-05:
      DOI: 10.1002/aic.14848
       
  • Modeling permporometry of mesoporous membranes using dynamic mean field
           theory
    • Authors: A. Rathi; J. R. Edison, D. M. Ford, P. A. Monson
      Abstract: Mesoporous inorganic membranes have significant potential for important small‐molecule separations like carbon dioxide recovery from stack emissions. However, tailoring materials for a given separation remains an outstanding problem. Preferential adsorption, layering and capillary effects, and surface flow are key mechanisms that determine permeation rates and are ultimately linked to the mesopore characteristics. To further the understanding of these systems we propose a modeling approach based on dynamic mean field theory, which has previously been used to study the dynamics of adsorption in mesoporous materials. This theory describes both relaxation dynamics and non equilibrium steady states in membranes and is fully consistent with a mean field density functional theory of the thermodynamics. We demonstrate the capabilities and promise of the approach by modeling a permporometry experiment, in which a light gas permeates through a mesopore in the presence of a condensable vapor at a controlled relative pressure. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-21T00:43:28.411103-05:
      DOI: 10.1002/aic.14846
       
  • Process synthesis for cascade refrigeration system based on exergy
           analysis†
    • Authors: Ha Dinh; Jian Zhang, Qiang Xu
      Abstract: Refrigeration system holds an important role in chemical/petrochemical processes. The traditional cascade refrigeration system (CRS) used in ethylene plants contains multiple refrigerants working at multiple temperature/pressure levels. In this study, a general methodology is developed for the optimal process synthesis of a CRS based on exergy analysis. This procedure involves four stages: i) refrigeration system exergetic analysis; ii) optimization model development for simultaneous synthesis of refrigeration system and heat exchanger network (HEN); iii) HEN configuration; and iv) final solution validation. The exergy‐temperature chart is employed to comprehensively analyze a CRS. A mathematical model is presented to minimize total compressor shaft work of the HEN‐considered CRS, where multiple recycling loops satisfying all cooling/heating demands are simultaneously addressed. The optimal solution is examined by rigorous simulations to verify its feasibility and consistency. The efficacy of the developed methodology is demonstrated by a case study of a propylene CRS in an ethylene plant. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-17T16:10:47.092361-05:
      DOI: 10.1002/aic.14843
       
  • Numerical study of pipeline restart of weakly compressible irreversibly
           thixotropic waxy crude oils
    • Authors: Lalit Kumar; Chris Lawrence, Yansong Zhao, Kristofer Paso, Brian Grimes, Johan Sjöblom
      Abstract: A 3D axisymmetric model is developed to predict pressure wave propagation processes during gelled waxy oil pipeline restart operations. A finite volume method is implemented on a staggered grid. An iterative predictor‐corrector algorithm provides solutions to the combined parabolic‐hyperbolic set of governing equations. A new shear‐history‐dependent thixotropic rheology model is proposed for pressure wave propagation computations. Moderate Reynolds number flows within the laminar regime are computed, demonstrating the impact of inertial effects. The results clearly illustrate the important mechanisms of pipeline restart. The nature of pressure wave propagation is governed by gel strength as well as overall fluid compressibility. Three sequential pressure wave propagation regimes are dominated by inertial, viscous and gel degradation phenomena, respectively. The viscous and gel degradation regimes are effectively coupled by imposed deformation conditions. For initially homogenous thixotropic gels, strain tends to localize near the pipeline wall, playing a central role in assuring the pipeline restart. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-17T16:10:12.461041-05:
      DOI: 10.1002/aic.14844
       
  • High‐throughput and comprehensive prediction of H2 adsorption in
           metal‐organic frameworks under various conditions
    • Authors: Yu Liu; Shuangliang Zhao, Honglai Liu, Ying Hu
      Abstract: High‐throughput prediction of H2 adsorption in MOF materials has been extended from a few specific conditions to the whole T, p space. The prediction is based on a classical density functional theory and has been implemented over 712 MOFs in 441 different conditions covering a wide range. Some testing materials show excellent behavior at low temperatures and obvious improvement at high temperatures compared to conventional MOFs. The structures of the best MOFs at high and low temperatures are totally different. Linear and nonlinear correlations between the two Langmuir parameters have been found at high and low temperatures, respectively. According to the analysis of the excess uptake, we found that the saturated pressure increases along with temperature in the low temperature region but decreases in the high temperature region. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-17T16:09:51.556324-05:
      DOI: 10.1002/aic.14842
       
  • Thermal transport model of a sorbent particle undergoing
           calcination–carbonation cycling
    • Authors: Lindsey Yue; Wojciech Lipiński
      Abstract: A numerical model coupling transient radiative, convective, and conductive heat transfer, mass transfer, and chemical kinetics of heterogeneous solid–gas reactions has been developed for a semi‐transparent, non‐uniform, and non‐isothermal particle undergoing cyclic thermochemical transformations. The calcination–carbonation reaction pair for calcium oxide looping is selected as the model cycle because of its suitability for solar‐driven carbon dioxide capture. The analyzed system is a single, porous particle undergoing thermochemical cycling in an idealized, reactor‐like environment. The model is used to investigate two cases distinguished by the length of the calcination and carbonation periods. The calcination–carbonation process for a single particle is shown to become periodic after three cycles. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-16T04:27:19.167469-05:
      DOI: 10.1002/aic.14840
       
  • Investigation of the Heat Transfer Intensification Mechanism for a New
           Fluidized Catalyst Cooler
    • Authors: Xiuying Yao; Xiao Han, Yongmin Zhang, Chunxi Lu
      Abstract: A small cold model was employed to investigate the heat transfer mechanism for a new fluidized catalyst cooler. Local heat transfer coefficients (h) and tube surface hydrodynamics were systematically measured by a specially designed heat tube and an optical fiber probe. The higher total h further validated the feasibility of the heat transfer intensification method employed in the new catalyst cooler, which indicated that the induced higher packet renewal frequency due to the non‐uniform gas distribution played a dominant role in its increased hs. Strongest heat transfer intensification effect was located at r/Rw>0.8 below the heat transfer intensification height. The changes of the mean packet residence time in the radial and axial directions and with superficial gas velocity were all agreeable with the measured hs according to the packet renewal theory. This further demonstrated the feasibility of the experimental method for tube surface hydrodynamics. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-15T00:41:02.872059-05:
      DOI: 10.1002/aic.14841
       
  • Aggregation of silica nanoparticles in an aqueous suspension
    • Authors: Lande Liu
      Abstract: Aggregation affects the stability of the nanoparticles in fluids. For hydrophilic particles in aqueous suspensions, zeta potential becomes a common measure to control the stability of the particles. However, it is not clear how zeta potential impacts on the interaction of the particles during their close range contact when the hydration repulsion arises strongly. This paper demonstrates a method that uses the kinetic theory of aggregation for an aggregation system of changing zeta potential to determine the hydration repulsion and the aggregation efficiency. It was found that the hydration repulsion has an equivalent electrical potential of 30 mV on the stem surface of the particles and an exponential decay length of 2.77 Å. This hydration potential is equivalent to 12 mV zeta potential and contributes 29% to the aggregation coefficient that is 5.5 × 10−6 for a 30 mV zeta potential stabilised silica particle suspension. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-09T16:14:21.241866-05:
      DOI: 10.1002/aic.14839
       
  • A robust mixed‐conducting multichannel hollow fiber membrane reactor
    • Authors: Jiawei Zhu; Shaobin Guo, Gongping Liu, Zhengkun Liu, Zhicheng Zhang, Wanqin Jin
      Abstract: To accelerate the commercial application of mixed‐conducting membrane reactor for catalytic reaction processes, a robust mixed‐conducting multichannel hollow fiber (MCMHF) membrane reactor was constructed and characterized in this work. The MCMHF membrane based on reduction‐tolerant and CO2‐stable SrFe0.8Nb0.2O3‐δ (SFN) oxide not only possesses a good mechanical strength, but also has a high oxygen permeation flux under air/He gradient, which is about four times that of SFN disk membrane. When partial oxidation of methane (POM) was performed in the MCMHF membrane reactor, excellent reaction performance (oxygen flux of 19.2 ml·min−1·cm−2, hydrogen production rate of 54.7 ml·min−1·cm−2, methane conversion of 94.6% and the CO selectivity of 99%) was achieved at 1173 K. And also, the MCMHF membrane reactor for POM reaction was operated stably for 120 h without obvious degradation of reaction performance. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-09T16:14:01.577761-05:
      DOI: 10.1002/aic.14835
       
  • Accuracy and optimal sampling in monte carlo solution of population
           balance equations
    • Authors: Xi Yu; Michael J Hounslow, Gavin K Reynolds
      Abstract: Implementation of a Monte Carlo simulation for the solution of population balance equations requires choice of initial sample number (N0), number of replicates (M) and number of bins for probability distribution reconstruction (n). It is found that Squared Hellinger Distance, H2, is a useful measurement of the accuracy of MC simulation, and can be related directly to N0, M and n. Asymptotic approximations of H2 are deduced and tested for both 1D and 2D PBEs with coalescence. The CPU cost, C, is found in a power‐law relationship, C= aMN0b, with the CPU cost index, b, indicating the weighting of N0 in the total CPU cost. n must be chosen to balance accuracy and resolution. For fixed n, M×N0 determines the accuracy of MC prediction; if b>1, then the optimal solution strategy uses multiple replications and small sample size. Conversely if 0
      PubDate: 2015-04-09T16:13:41.436584-05:
      DOI: 10.1002/aic.14837
       
  • A hierarchical method to integrated solvent and process design of physical
           CO2 absorption using the SAFT‐γ mie approach
    • Authors: J. Burger; V. Papaioannou, S. Gopinath, G. Jackson, A. Galindo, C. S. Adjiman
      Abstract: Molecular‐level decisions are increasingly recognised as an integral part of process design. Finding the optimal process performance requires the integrated optimisation of process and solvent chemical structure, leading to a challenging mixed‐integer nonlinear programming (MINLP) problem. We present the formulation of such problems when using a group contribution version of the statistical associating fluid theory (SAFT‐ γ Mie) to predict the physical properties of the relevant mixtures reliably over process conditions. To solve the challenging MINLP, a novel hierarchical methodology for integrated process and solvent design (HiOpt) is presented. Reduced models of the process units are developed and used to generate a set of initial guesses for the MINLP solution. The methodology is applied to the design of a physical absorption process to separate carbon dioxide from methane, using a large selection of ethers as the molecular design space. The solvents with best process performance are found to be poly(oxymethylene)dimethylethers. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-09T16:13:22.051972-05:
      DOI: 10.1002/aic.14838
       
  • Modeling heterogeneous photocatalytic inactivation of E.coli using
           suspended and immobilized TiO2 reactors
    • Authors: M. Kacem; G. Plantard, N. Wery, V. Goetz
      Abstract: A study was carried out to develop a kinetic model of the photocatalytic inactivation of E. coli using different TiO2 catalysts. The model developed is based on a reaction scheme that involves effectively coupling mass transfer fluxes between bacteria and catalyst surface on one hand and bacterial degradation reaction on the other. The photocatalytic results were derived from experiments led in a batch reactor under both dark and UV irradiation conditions. Using a reference catalyst the robustness of the developed model was tested under solar conditions. The experimental data validated the model as successfully able to reproduce evolutions in the viable bacteria concentration in the range of parameters studied without any further adjustment of the kinetic parameters. The model was used to simulate the bacterial degradation kinetics under different working conditions in order to describe the partitioning of both bacterial adhesion and photocatlaytic reaction in the solution to be treated This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-09T16:13:03.077146-05:
      DOI: 10.1002/aic.14834
       
  • Co‐gasification of woody biomass and sewage sludge in a
           fixed‐bed downdraft gasifier
    • Authors: Zhehan Ong; Yongpan Cheng, Thawatchai Maneerung, Zhiyi Yao, Yanjun Dai, Yen Wah Tong, Chi‐Hwa Wang
      Abstract: In this work, experimental and numerical studies of co‐gasification of woody biomass and sewage sludge have been carried out. The gasification experiments were performed in a fixed‐bed downdraft gasifier and the experimental results show that 20 wt. % dried sewage sludge in the feedstock was effectively gasified to generate producer gas comprising over 30 vol. % of syngas with an average lower heating value of 4.5 MJ/Nm3. Further increasing sewage sludge content to 33 wt. % leads to the blockage of gasifier, which is resulted from the formation of agglomerated ash. The numerical models were then developed to simulate the reactions taking place in four different zones of the gasifier (i.e. drying, pyrolysis, combustion and reduction zones) and to predict the producer gas composition and cold gas efficiency (CGE). The deviation between the numerical and experimental results obtained in this study was lower than 10%. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-09T16:12:30.486522-05:
      DOI: 10.1002/aic.14836
       
  • Erratum
    • PubDate: 2015-04-09T10:21:34.009885-05:
      DOI: 10.1002/aic.14811
       
  • Optimal distribution of temperature driving forces in
           low‐temperature heat transfer
    • Authors: Bjørn Austbø; Truls Gundersen
      Abstract: This paper provides a fairly extensive review of research on optimal distribution of driving forces in heat transfer processes. Four different guidelines for specifying the temperature profiles in heat exchangers have been compared. Not surprisingly, the irreversibilities due to heat transfer were found to be minimized when the temperature difference is proportional to the absolute temperature. Comparing a design with an optimal temperature profile and a design with a uniform temperature difference throughout the heat exchanger, sensitivity analyses illustrated that savings in irreversibilities increase with decreasing temperature level and increasing temperature span for the cooling load. Heat exchanger size was found to be of negligible importance. The results indicated that optimal utilization of heat exchanger area is of little importance for processes operating above ambient temperature, while significant savings can be obtained by optimal distribution of temperature driving forces in processes below ambient temperature. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:44:18.558876-05:
      DOI: 10.1002/aic.14832
       
  • Integration of scheduling, design and control of multi‐product
           chemical processes under uncertainty
    • Authors: Bhushan P. Patil; Eduardo Maia, Luis A. Ricardez‐Sandoval
      Abstract: This study focuses on the development of a methodology that addresses the simultaneous design, scheduling and control of multiproduct processes. The proposed methodology takes into account the influence of disturbances by the identification of their critical frequency, which is used to quantify the worst‐case variability in the controlled variables via frequency response analysis. The uncertainty in the demands of products has also been addressed by creating critical demand scenarios with different probabilities of occurrence, while the nominal stability of the system has been ensured. Two case studies have been developed as applications of the methodology. The first case study focuses on the comparison of classical semi‐sequential approach against the simultaneous methodology developed in this work, while the second case study demonstrates the capability of the methodology in application to a large‐scale nonlinear system. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:44:00.242568-05:
      DOI: 10.1002/aic.14833
       
  • Simulation study of the effect of wall roughness on the dynamics of
           granular flows in rotating semi‐cylindrical chutes
    • Authors: S.S. Shirsath; J.T. Padding, H.J.H. Clercx, J.A.M. Kuipers
      Abstract: A discrete element model (DEM) is used to investigate the behavior of spherical particles flowing down a semi‐cylindrical rotating chute. The DEM simulations are validated by comparing with Particle Tracking Velocimetry (PTV) results of spherical glass particles flowing through a smooth semi‐cylindrical chute at different rotation rates of the chute. The DEM model predictions agree well with experimental results of surface velocity and particle bed height evolution. The validated DEM model is used to investigate the influence of chute roughness on the flow behaviour of monodisperse granular particles in rotating chutes. To emulate different base roughnesses, a rough base is constructed out of a square close packing of fixed spherical particles with a diameter equal to, smaller, or larger than the flowing particles. Finally, the DEM model is used to study segregation in a binary density mixture for different degrees of roughness of the chute. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:43:42.997403-05:
      DOI: 10.1002/aic.14828
       
  • Consideration of low viscous droplet breakage in the framework of the wide
           energy spectrum and the multiple fragments
    • Authors: Luchang Han; Shenggao Gong, Yaowen Ding, Jin Fu, Ningning Gao, He'an Luo
      Abstract: An improved model for low viscous droplet breakage has been developed. Unlike the previous work that considered the inertia subrange and adopted the assumption of binary breakage, this work considered the breakage of droplets in the framework of the multiple fragments and the wide energy spectrum (i.e. including the dissipation range, the inertia subrange and the energy containing range simultaneously). The previous interactions between the droplet and the surrounding fluid have been considered through introducing the interaction forces. The effect of the surface deformation and oscillation resulting from these interactions on the constraints of multiple breakages has been accounted for. These factors have been neglected in the existing models. The wide energy spectrum distribution was found to have an important effect on the non‐monotone evolution of breakage frequency with increasing parent droplet size. The cumulative volume fractions predicted by this work showed a better agreement with the experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:42:51.464663-05:
      DOI: 10.1002/aic.14830
       
  • An electrolyte CPA equation of state for mixed solvent electrolytes
    • Authors: Bjørn Maribo‐Mogensen; Kaj Thomsen, Georgios M. Kontogeorgis
      Abstract: Despite great efforts over the past decades, thermodynamic modeling of electrolytes in mixed solvents is still a challenge today. The existing modeling frameworks based on activity coefficient models are data‐driven and require expert knowledge to be parameterized. It has been suggested that the predictive capabilities could be improved through the development of an electrolyte equation of state. In this work, the Cubic Plus Association (CPA) Equation of State is extended to handle mixtures containing electrolytes by including the electrostatic contributions from the Debye‐Hückel and Born terms using a self‐consistent model for the static permittivity. A simple scheme for parameterization of salts with a limited number of parameters is proposed and model parameters for a range of salts are determined from experimental data of activity and osmotic coefficients as well as freezing point depression. Finally, the model is applied to predict VLE, LLE, and SLE in aqueous salt mixtures as well as in mixed solvents. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:42:34.244232-05:
      DOI: 10.1002/aic.14829
       
  • Characterization of liquid‐liquid dispersions with variable
           
    • Authors: Michal Vonka; Miroslav Soos
      Abstract: Sustaining stable liquid‐liquid dispersion with the desired drop size still relies on experimental correlations, which do not reflect our understanding of the underlying physics and have limited prediction capability. The complex behaviour of liquid‐liquid dispersions inside a stirred tank, which is equipped with a Rushton turbine, was characterized by a combination of Computational Fluid Dynamics (CFD) and Population Balance Equations (PBE). PBE took into account both the drop coalescence and breakup. With increasing drop viscosity the resistance to drop breakage increases, which was introduced by the local criteria for drop breakup in the form of the local critical Webber number (). The dependency of on the drop viscosity was derived from the experimental data available in the literature. Predictions of Sauter mean diameter agree well with the experimentally measured values allowing prediction of mean drop size as a function of variable viscosity, interfacial tension and stirring speed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T17:42:21.164492-05:
      DOI: 10.1002/aic.14831
       
  • A generalized procedure for the prediction of multicomponent adsorption
           equilibria
    • Authors: Austin Ladshaw; Sotira Yiacoumi, Costas Tsouris
      Abstract: Prediction of multicomponent adsorption equilibria has been investigated for several decades. While there are theories available to predict the adsorption behavior of ideal mixtures, there are few purely predictive theories to account for non‐idealities in real systems. Most models available for dealing with non‐idealities contain interaction parameters that must be obtained through correlation with binary‐mixture data. However, as the number of components in a system grows, the number of parameters needed to be obtained increases exponentially. Here, a generalized procedure is proposed, as an extension of the Predictive Real Adsorbed Solution Theory, for determining the parameters of any activity model, for any number of components, without correlation. This procedure is then combined with the Adsorbed Solution Theory to predict the adsorption behavior of mixtures. As this method can be applied to any isotherm model and any activity model, it is referred to as the Generalized Predictive Adsorbed Solution Theory. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-07T11:11:06.966511-05:
      DOI: 10.1002/aic.14826
       
  • Pilot‐scale studies of process intensification by cyclic
           distillation
    • Authors: Bogdan V. Maleta; Alexander Shevchenko, Olesja Bedruk, Anton A. Kiss
      Abstract: Process intensification in distillation systems receives much attention with the aim of increasing both energy and separation efficiency. Several technologies have been investigated and developed, as for example: dividing‐wall column, HiGee distillation, or internal heat‐integrated distillation. Cyclic distillation is a different method based on separate phase movement – achievable with specific internals and a periodic operation mode – that leads to key advantages: increased column throughput, reduced energy requirements, and better separation performance. This article is the first to report the performance of a pilot‐scale distillation column for ethanol‐water separation, operated in a cyclic mode. A comparative study is made between a pilot‐scale cyclic distillation column and an existing industrial beer column used to concentrate ethanol. Using specially designed trays that truly allow separate phase movement, the practical operation confirmed that 2.6 times fewer trays and energy‐savings of about 30% are possible as compared to classic distillation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-06T23:55:29.612385-05:
      DOI: 10.1002/aic.14827
       
  • Experimental Studies and Modeling of CO2 Solubility in High Temperature
           Aqueous CaCl2, MgCl2, Na2SO4, and KCl Solutions
    • Authors: Haining Zhao; Robert M. Dilmore, Serguei N. Lvov
      Abstract: The phase equilibria of CO2 and aqueous electrolyte solutions are important to various chemical‐, petroleum‐ and environmental‐related technical applications. In this study, we measured CO2 solubility in aqueous CaCl2, MgCl2, Na2SO4 and KCl solutions at a pressure of 15 MPa, the temperatures from 323 to 423 K, and the ionic strength from 1 to 6 mol kg−1. Based on the measured experimental CO2 solubility, the previous developed fugacity‐activity thermodynamic model for the CO2‐NaCl‐H2O system was extended to account for the effects of different salt specieson CO2 solubility in aqueous solutions at temperatures up to 523 K, pressures up to 150 MPa, and salt concentrations up to saturation. Comparisons of different models against literature data reveal a clear improvement of the proposed PSUCO2 model in predicting CO2 solubility in aqueous salt solutions. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-04T03:21:25.36965-05:0
      DOI: 10.1002/aic.14825
       
  • A low‐disturbance nonequilibrium molecular dynamics algorithm
           applied to the determination of thermal conductivities
    • Authors: Filipe A. Furtado; Charlles R. A. Abreu, Frederico W. Tavares
      Abstract: A new nonequilibrium molecular dynamics algorithm is proposed for the determination of thermal conductivity and other transport properties. The proposed algorithm aims at diminishing the energy drift problem observed in this type of method while conserving linear momentum and being compatible with constrained molecules. The features of the proposed algorithm are evaluated by determining thermal conductivities of water at 323 K, n‐octane at 300 K, and argon close to its triple point, and by comparing these results with those obtained using established methods. The analysis of systems presenting diverse molecular characteristics allowed us to assess the usefulness of the proposed algorithm. The energy drift and temperature variation were reduced in the range of 10–80%, depending on the parameters of the proposed algorithm and the characteristics of the system. The determined thermal conductivities showed good agreement when compared to experimental and simulation data. © 2015 American Institute of Chemical Engineers AIChE J, 2015
      PubDate: 2015-04-03T10:17:58.709766-05:
      DOI: 10.1002/aic.14803
       
  • Thermodynamics of protein aqueous solutions: From the structure factor to
           the osmotic pressure
    • Authors: Luís Fernando Mercier Franco; Cristiano Luis Pinto de Oliveira, Pedro de Alcântara Pessôa Filho
      Abstract: An analytical expression for the structure factor for globular proteins in aqueous solution is presented in this work. This expression was obtained considering a potential given by the sum of a hard core, a van der Waals attractive and a screened Coulomb contribution. Experimental data of Small Angle X‐Ray Scattering for bovine serum albumin in aqueous solutions containing sodium salts at different protein concentrations and pH values are also presented. The developed expression for the structure factor describes accurately these experimental data provided a dependence of the attractive parameter on protein concentration is established. An expression for the osmotic pressure was derived from the structure factor. With attractive parameters adjusted from X‐ray scattering data, the osmotic pressure of bovine serum albumin aqueous solutions could be predicted with very good agreement with experimental data. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-03T06:21:32.372128-05:
      DOI: 10.1002/aic.14802
       
  • Towards economical purification of styrene monomers: Eggshell Mo2C for
           front‐end hydrogenation of phenylacetylene
    • Authors: Min Pang; Zhengfeng Shao, Wei Xia, Xinkui Wang, Changhai Liang
      Abstract: We describe an eggshell Mo2C catalyst which is designed from the rapid combination of molybdate with melamine. In contrast to Pd‐based catalysts, the eggshell Mo2C operates effectively with a wide concentration window in high‐temperature gas phase hydrogenation of phenylacetylene thus an economical and energy‐efficient front‐end purification of styrene monomers might be possible. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-02T18:47:16.789707-05:
      DOI: 10.1002/aic.14822
       
  • A generalized model to predict minimum particle transport velocities in
           multiphase air‐water horizontal pipes
    • Authors: Kamyar Najmi; Alan L. Hill, Selen Cremaschi, Brenton S. McLaury, Siamack A. Shirazi
      Abstract: A new model is proposed to predict minimum flow rates required to constantly move particles in both intermittent and stratified flow regimes. The new model consists of a single‐phase flow model along with an appropriate length scale to be extended to multiphase flow regime. A comparison of the new model with experimental data in a multiphase air‐water flow shows that the new model is able to predict minimum flow rates well for a wide range of operating conditions. The new model can capture the effects of particle size, particle concentration and pipe size as confirmed by experimental data. A comparison of the new model with previously proposed models in the literature shows that the new model improves critical velocity predictions significantly. Moreover, the new model is the only model that takes into account the effect of particle concentration and can predict critical velocity in both intermittent and stratified flow regimes. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-02T18:46:35.130779-05:
      DOI: 10.1002/aic.14824
       
  • Simultaneous integration of water and energy in heat‐integrated
           water allocation networks
    • Authors: Zuming Liu; Yiqing Luo, Xigang Yuan
      Abstract: This article proposes a new methodology for simultaneous integration of water and energy in heat‐integrated water allocation networks (WAHEN). A novel disjunctive model is first developed to determine an optimal water allocation network (WAN) where water and energy are integrated in one step. Based on the optimal WAN, a detailed heat exchanger network (HEN) to satisfy the utility target is then synthesized. Although the final network structure is obtained through two steps, the targets of freshwater and utility are optimized simultaneously. The proposed method has specific advantages. First of all, it can capture a trade‐off among freshwater usage, utility consumption and direct heat transfer by non‐isothermal mixing. Second, it can greatly reduce the complexity of subsequent HEN design. Finally, it is effective for simultaneous water and energy integration in large‐scale WAHEN systems. The advantages and applicability of this new method are illustrated by three examples from literature. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-02T18:46:09.148186-05:
      DOI: 10.1002/aic.14823
       
  • Numerical study of turbulent liquid‐liquid dispersions
    • Authors: A.E. Komrakova; D. Eskin, J.J. Derksen
      Abstract: A numerical approach is developed to gain fundamental insight in liquid‐liquid dispersion formation under well‐controlled turbulent conditions. The approach is based on a free energy lattice Boltzmann equation method, and relies on detailed resolution of the interaction of the dispersed and continuous phase at the microscopic level, including drop breakup and coalescence. The capability of the numerical technique to perform direct numerical simulations of turbulently agitated liquid‐liquid dispersions is assessed. Three‐dimensional simulations are carried out in fully‐periodic cubic domains with grids of size 1003‐10003. The liquids are of equal density. Viscosity ratios (dispersed phase over continuous phase) are in the range 0.3 to 1.0. The dispersed phase volume fraction varies from 0.001 to 0.2. The process of dispersion formation is followed and visualized. The size of each drop in the dispersion is measured in‐line with no disturbance of the flow. However, the numerical method is plagued by numerical dissolution of drops that are smaller than 10 times the lattice spacing. It is shown that to mitigate this effect it is necessary to increase the resolution of the Kolmogorov scales, such as to have a minimum drop size in the range 20‐30 lattice units [lu]. Four levels of Kolmogorov length scale resolution have been considered\eta_K=1, 2.5, 5 and 10 [lu]. In addition, the numerical dissolution reduces if the concentration of the dispersed phase is increased. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-02T18:45:43.104236-05:
      DOI: 10.1002/aic.14821
       
  • On the simultaneous description of h‐bonding and dipolar
           interactions with point charges in force field models
    • Authors: Kai Langenbach; Cemal Engin, Steffen Reiser, Martin Horsch, Hans Hasse
      Abstract: H‐bonding and polar interactions occur together in real fluids, but are of different nature and have different effects on macroscopic properties. Nevertheless, both are usually described by point charges in force field models. We show that, despite this, the two effects can be separated. We study a simple model fluid: a single Lennard‐Jones site with two opposing point charges q placed in the center of the Lennard‐Jones site and at a distance d. By suitably varying both d and q the dipole moment μ is kept constant. Both μ and d are systematically varied to study the properties of the resulting models, including H‐bonding, which is determined using a geometric criterion from literature. We show that d can be used for tuning the H‐bonding strength and, thus, polarity and H‐bonding can be adjusted individually. The study of a second related model with symmetrically positioned point charges does not reveal this separation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-02T18:45:17.356024-05:
      DOI: 10.1002/aic.14820
       
  • Enhanced gravimetric CO2 capacity and viscosity for ionic liquids with
           cyanopyrrolide anion
    • Authors: Paul Brown; Burcu E. Gurkan, T. Alan Hatton
      Abstract: “Ionic Liquids are considered as alternative solvents for the separation of CO2 from flue gas due mainly to their CO2 affinity and thermal stability. This paper systematically investigates the cation architecture in a matrix of ammonium and mostly phosphonium‐based ionic liquids with 2‐cyanopyrrolide as the anion to evaluate its impact on gravimetric CO2 absorption capacity, viscosity and thermal stability; the three fundamental properties vital for application realization. Among the investigated ILs, [P2,2,2,8][2‐CNpyr] demonstrated the lowest viscosity, 95 cP at 40 ºC, and highest CO2 uptake, 114 mg CO2/g IL at 40 ºC. Combined effects of asymmetry and the optimized chain lengths also resulted in improved thermal stability for [P2,2,2,8][2‐CNpyr], with a mass loss rate of 1.35 x 10−6 g h−1 (0.0067 mass % h−1) at 80 ºC.” This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-01T15:23:17.597522-05:
      DOI: 10.1002/aic.14819
       
  • Dew‐point measurements for water in compressed carbon dioxide
    • Authors: Christopher W. Meyer; Allan H. Harvey
      Abstract: When transporting CO2 for sequestration, it is important to know the water dew point in order to avoid condensation that can lead to corrosion. We have constructed a flow apparatus to measure the water content at saturation in a compressed gas. A saturator humidifies the flowing gas by equilibrating it with liquid water. Then, a gravimetric hygrometer measures the water mole fraction of the humid gas. We report dew‐point data for H2O in CO2 on six isotherms between 10 °C and 80 °C at pressures from 0.5 MPa to 5 MPa. Our uncertainties in water content at the dew point (expanded uncertainty with coverage factor k=2) are on average 0.3%, significantly smaller than in any previous work. The data have been analyzed to extract the interaction second virial coefficient; our values are consistent with the theoretical estimates of Wheatley and Harvey but have a much smaller uncertainty. This article is protected by copyright. All rights reserved.
      PubDate: 2015-04-01T15:19:24.165662-05:
      DOI: 10.1002/aic.14818
       
  • Delignification of intact biomass and cellulosic coproduct of
           acid‐catalyzed hydrolysis
    • Authors: Majid Soleimani; Lope G. Tabil, Catherine Niu
      Abstract: The kinetics of acid‐catalyzed hemicellulose removal and also alkaline delignification of oat hull biomass were investigated. All three operational parameters namely, catalyst concentration (0.10–0.55 N H2SO4), temperature (110–130°C), and residence time (up to 150 min) affected the efficiency of hemicellulose removal, with 100% of hemicellulose removed by appropriate selection of process parameters. Analysis of delignification kinetics (in the temperature range of 30–100°C) indicated that it can be expressed very well by a two‐phase model for the crude biomass and also for the hemicellulose‐prehydrolyzed material. The application of acid‐catalyzed prehydrolysis improved the capacity of lignin dissolution especially at lower temperatures (30 and 65°C) and accelerated the dissolution of lignin. This acceleration of delignification by prehydrolysis was possible at all levels of temperature in the bulk phase; however, results were more significant at the lower temperatures in the terminal phase. © 2015 American Institute of Chemical Engineers AIChE J, 2015
      PubDate: 2015-04-01T08:53:25.220682-05:
      DOI: 10.1002/aic.14794
       
  • Numerical study of laminar core‐annular flow in a torus and in a
           90° pipe bend
    • Authors: Gijs Ooms; Mathieu J. B. M. Pourquie, Jerry Westerweel
      Abstract: A numerical study has been made of laminar core‐annular through a torus. It is a follow‐up of the study by Picardo and Pushpavanam, AIChE J. 2013;59(12):4871–4886, who obtained an analytical solution for the case that the core is concentric and circular. In our study, we investigated the possibility of eccentric core‐annular flow and the deformation of the core‐annular interface. We found that a stable eccentric core position is possible, which is shifted in the direction of the inner or outer side of the torus depending on the balance of the normal stresses at the core‐annular interface. When these stresses are too far off from those for concentric and circular core‐annular flow, fouling of the wall occurs. We compared the results of core‐annular flow in a torus with those for a 90° pipe bend and found that the flow pattern in the torus is representative for the flow pattern in the bend. © 2015 American Institute of Chemical Engineers AIChE J, 2015
      PubDate: 2015-03-31T11:13:57.672037-05:
      DOI: 10.1002/aic.14796
       
  • A consecutive microreactor system for the synthesis of caprolactam with
           high selectivity
    • Authors: Kai Wang; Jisong Zhang, Chen Zheng, Chen Dong, Yangcheng Lu, Guangsheng Luo
      Abstract: A microreactor system containing two consecutive microreactors and a stirred vessel was developed for the improvement of selectivity of caprolactam (CPL) synthesis. The first microreactor was used to conduct the reaction of cyclohexanecarboxylic acid and oleum, and 97% selectivity for the intermediate product, named mixed anhydride, was obtained. The mixed anhydride then quickly reacted with nitroso‐sulfuric acid in the second microreactor, and the reaction was completed in the vessel, where CPL selectivity reached 93.9%, a much higher value than that achieved either in a control experiment with a batch reactor or in industrial process. The advantage of microreactors is that they can provide high‐quality mixed anhydride and can mix it quickly with the nitroso‐sulfuric acid prior to reaction in the vessel reactor, which, from an engineering standpoint, gives better performance than the traditional syringe‐fed method that is common in chemical synthesis. © 2015 American Institute of Chemical Engineers AIChE J, 2015
      PubDate: 2015-03-31T11:13:31.418275-05:
      DOI: 10.1002/aic.14797
       
  • The Future of the Lecture
    • Authors: E. L. Cussler
      PubDate: 2015-03-31T09:21:47.131094-05:
      DOI: 10.1002/aic.14807
       
  • Pore‐size evaluation and gas transport behaviors of microporous
           membranes: An experimental and theoretical study
    • Authors: Gang Li; Hye Ryeon Lee, Hiroki Nagasawa, Masakoto Kanezashi, Tomohisa Yoshioka, Toshinori Tsuru
      Abstract: A modified gas‐translation (GT) model based on a GT mechanism was successfully applied to the pore‐size evaluation and gas transport‐behavior analysis of microporous membranes with different pore‐size distributions. Based on the gas permeation results of three microporous membranes derived from different alkoxides, the effects of activation energy and the selection of a standard gas on the pore‐size evaluation were discussed in a comparative study. The presence of nano‐sized defects had an important influence on the gas permeation performance of microporous membranes, depending largely on the original pore size of the membrane in question. Moreover, the gas‐separation effect of the pore‐size distribution in a silica membrane was theoretically studied, and revealed a significant increase in gas permeance for relatively large gas species but not for small ones. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:39:19.505342-05:
      DOI: 10.1002/aic.14812
       
  • A compact photomicroreactor design for kinetic studies of gas‐liquid
           photocatalytic transformations
    • Authors: Yuanhai Su; Volker Hessel, Timothy Noël
      Abstract: A compact photomicroreactor assembly consisting of a capillary microreactor and small‐scale LEDs was developed for the study of reaction kinetics in the gas‐liquid photocatalytic oxidation of thiophenol to phenyl disulfide within Taylor flow. The importance of photons was convincingly shown by a suction phenomenon due to the fast consumption of oxygen. Mass transfer limitations were evaluated and an operational zone without mass transfer effects was chosen to study reaction kinetics. Effects of photocatalyst loading and light sources on the reaction performance were investigated. Reaction kinetic analysis was performed to obtain reaction orders with respect to both thiophenol and oxygen based on heterogeneous and homogeneous experimental results, respectively. The Hatta number further indicated elimination of mass transfer limitations. Reaction rate constants at different photocatalyst loadings and different photon flux were calculated. Furthermore, the advantages of this photomicroreactor assembly for studying gas‐liquid photocatalytic reaction kinetics were demonstrated as compared with batch reactors. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:33:46.117974-05:
      DOI: 10.1002/aic.14813
       
  • Emulation of gas‐liquid flow in packed beds for offshore floating
           applications using a swell simulation hexapod
    • Authors: Gnouyaro P. Assima; Amir Motamed‐Dashliborun, Faïçal Larachi
      Abstract: A laboratory‐scale packed column was positioned on a 6‐degree‐of‐freedom swell simulation hexapod to emulate the hydrodynamics of packed bed scrubbers/reactors onboard offshore floating systems. The bed was instrumented with wire mesh capacitance sensors to measure liquid saturation and velocity fields, flow regime transition, liquid maldistribution, and tracer radial and axial dispersion patterns while robot was subject to sinusoidal translation (sway, heave) and rotation (roll, roll + pitch, yaw) motions at different frequencies. Three metrics were defined to analyze the deviations induced by the various column motions, namely, coefficient of variation and degree of uniformity for liquid saturation fluctuating fields, and effective Péclet number. Non‐tilting oscillations led to frequency‐independent maldistribution while tilting motions induced swirl/zigzag secondary circulation and prompted non‐uniform maldistribution oscillations that deteriorated with decreasing frequencies. Regardless of excited degree of freedom, a qualitative loss of plug‐flow character was observed compared to static vertical beds which worsened as frequencies decreased. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:31:09.083555-05:
      DOI: 10.1002/aic.14816
       
  • Multi‐objective optimization for designing and operating more
           sustainable water management systems for a city in Mexico
    • Authors: Ma. Guadalupe Rojas‐Torres; Gonzalo Guillén‐Gosálbez, Fabricio Nápoles‐Rivera, José María Ponce‐Ortega, Laureano Jiménez‐Esteller, Medardo Serna‐González
      Abstract: This paper proposes a multi‐objective optimization model for the design of a macroscopic water system of a Mexican city that solves simultaneously the planning and scheduling of water storage and distribution tasks. The model, which considers rainwater harvesting and reclaimed water reusing as alternative water sources, maximizes the revenues from water sales and minimizes simultaneously the water consumption and land use. A case study based on the city of Morelia in Mexico was solved. It was found that the use of alternative water sources (such as harvested rainwater) along with an appropriate planning and scheduling of storage and distribution tasks have the potential to reduce the pressure over natural reservoirs significantly. Our approach considers simultaneously economic and environmental concerns, thereby contributing to the implementation of more sustainable alternatives in urban water distribution. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:30:12.812187-05:
      DOI: 10.1002/aic.14814
       
  • On‐line control of crystal properties in non‐isothermal
           antisolvent crystallization
    • Authors: Navid Ghadipasha; Jose A. Romagnoli, Stefania Tronci, Roberto Baratti
      Abstract: This paper deals with the issues regarding the design and implementation of on‐line optimal control strategies of crystal properties in non‐isothermal antisolvent crystallization processes to control particles' mean size and standard deviation. The one‐dimensional Fokker‐Planck equation (FPE) is used to represent the dynamic characteristics of the crystal growth and generate iso‐mean and iso‐standard deviation curves. Using controllability tools it is demonstrated that the system is ill conditioned in the whole operational range, posing limitations on the achievable control performance. To circumvent the problem, a control strategy is formulated by pairing crystals' mean size with antisolvent feed rate and manipulating temperature to control the standard deviation. A novel digital image texturing analysis approach is discussed and implemented to track crystals' size distribution along the experiment and providing the on‐line information for further feedback control action. Subsequently, alternative control strategies are implemented and tested to achieve a desired crystal size distribution (CSD). This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:27:59.122586-05:
      DOI: 10.1002/aic.14815
       
  • Aldol condensation of n‐butyraldehyde in a biphasic stirred tank
           reactor: Experiments and models
    • Authors: Shinbeom Lee; Arvind Varma
      Abstract: To model a biphasic stirred tank reactor, intrinsic reaction kinetics and interfacial area are required. In this study, reactor modeling for n‐butyraldehyde aldol condensation was investigated under industrially relevent conditions. The interfacial area in the reactor was directly measured using a borescope system under appropriate temperature, NaOH concentration and rpm conditions. To estimate the interfacial area, a semi‐empirical correlation was developed, which provides good estimates within ±15% error. The reactor model based on two‐film theory was developed, combining the interfacial area and intrinsic reaction kinetics reported in our prior work. The model was verified by reaction experiments in the range 0.05‐1.9M NaOH, 80‐130 oC and 600‐1000 rpm. The prediction errors using the interfacial area from direct measurements and the correlation were ±8% and ±15%, respectively, suggesting that the model accuracy may be improved with better interfacial area estimation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-30T17:25:03.729629-05:
      DOI: 10.1002/aic.14817
       
  • Modelling of a membrane reactor system for crude palm oil
           transesterification. Part I: Chemical and phase equilibrium
    • Authors: Pin Pin Oh; Mei Fong Chong, Harrison Lik Nang Lau, Junghui Chen, Yuen May Choo
      Abstract: Using a membrane reactor for reversible transesterification reaction involves reaction and product separation within a single unit. However, a pseudo‐homogeneous reaction and heterogeneous separation must be maintained for successful membrane reactor operation. Present research is aimed to develop an integrated model of chemical and phase equilibrium (CPE) and modified Maxwell‐Stefan equation that describes the simultaneous CPE and mass transport phenomena of biodiesel production from crude palm oil (CPO) by using a membrane reactor. In the first part of this work, a systematic approach describing simultaneous CPE of CPO transesterification in the membrane reactor was developed with the reconciliation of transesterification reaction and phase equilibrium that involves six‐component. The results revealed that regressed apparent equilibrium constant, Keq value of 17.557±1.51% was higher than the literatures. This indicates that forward reaction of the reversible CPO transesterification is much favored in the membrane reactor than the conventional reactor. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:19:34.541869-05:
      DOI: 10.1002/aic.14806
       
  • Developing intermolecular‐potential models for use with the
           SAFT‐VR Mie Equation of State
    • Authors: Simon Dufal; Thomas Lafitte, Amparo Galindo, George Jackson, Andrew J. Haslam
      Abstract: A major advance in the statistical associating fluid theory for potentials of variable range (SAFT‐VR) has recently been made with the incorporation of the Mie (generalized Lennard‐Jones) interaction between the segments comprising the molecules in the fluid. [Lafitte et al. J. Chem. Phys. 2013;139:154504] The Mie potential offers greater versatility in allowing one to describe the softness/hardness of the repulsive interactions and the range of the attractions, which govern fine details of the fluid‐phase equilibria and thermodynamic derivative properties of the system. In our current work, the SAFT‐VR Mie equation of state is employed to develop models for a number of prototypical fluids, including some of direct relevance to the oil and gas industry: methane, carbon dioxide and other light gases, alkanes, alkyl benzenes, and perfluorinated compounds. A complication with the use of more‐generic force fields like the Mie potential is the additional number of parameters that have to be considered to specify the interactions between the molecules, leading to a degree of degeneracy in the parameter space. A formal methodology to isolate intermolecular‐potential models and assess the adequacy of the description of the thermodynamic properties in terms of the complex parameter space is developed. Fluid‐phase equilibrium properties (the vapour pressure and saturated‐liquid density) are chosen as the target properties in the refinement of the force fields; the predictive capability for other properties such as the enthalpy of vaporization, single‐phase density, speed of sound, isobaric heat capacity, and Joule‐Thomson coefficient, is appraised. It is found that an overall improvement of the representations of the thermophysical properties of the fluids is obtained by using the more‐generic Mie form of interaction; in all but the simplest of fluids, one finds that the Lennard‐Jones interaction is not the most appropriate. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:19:08.693497-05:
      DOI: 10.1002/aic.14808
       
  • Investment optimization model for freshwater acquisition and wastewater
           handling in shale gas production
    • Authors: Linlin Yang; Meagan Mauter, Robert Dilmore, Ignacio E. Grossmann
      Abstract: Major challenges of water use in the drilling and fracturing process in shale gas production are large volumes required in a short‐period of time and the nonsteady nature of wastewater treatment. We present a new mixed‐integer linear programming (MILP) model for optimizing capital investment decisions for water use for shale gas production through a discrete‐time representation of the State‐Task Network. The objective is to minimize the capital cost of impoundment, piping, and treatment facility, and operating cost including freshwater, pumping, and treatment. The goal is to determine the location and capacity of impoundment, the type of piping, treatment facility locations and removal capability, freshwater sources, as well as the frac schedule. In addition, we examine the impact of several factors such as limiting truck hauling and increasing flowback volume on the solution. A case study is optimized to illustrate the application of the proposed formulation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:18:47.000691-05:
      DOI: 10.1002/aic.14804
       
  • Mesoscopic coarse‐grained simulations of hydrophobic charge
           induction chromatography (HCIC) for protein purification
    • Authors: Gaobo Yu; Jie Liu, Jian Zhou
      Abstract: Mesoscopic coarse‐grained simulations are adopted to investigate interfacial mechanisms of hydrophobic charged induction chromatography for protein purification by regulating pH. Simulations results indicate that: (i) lysozyme can be adsorbed mainly with “top end‐on” and “bottom end‐on” orientation on hydrophobic surfaces, dominated by the two hydrophobic regions located at both ends of lysozyme's long axis. Elution from the “top end‐on” orientation is more difficult than that from the “bottom end‐on” orientation; (ii) a higher ligand density can get a faster adsorption rate and stronger adsorption. Interestingly, the effect of ligand density on the desorption is mainly determined by the distribution probability of the positively charged groups of ligands; (iii) a higher ionic strength can lead to a wider orientation distribution, a stronger adsorption and a lower elution rate. This work might provide an efficient way to optimize the operating conditions and designing novel ligands. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:18:25.392627-05:
      DOI: 10.1002/aic.14805
       
  • A model‐based precipitation study of copper‐based catalysts
    • Authors: Martin A. J. Hartig; Nikolas Jacobsen, Alexander Leuthold, Wolfgang Peukert
      Abstract: Numerical methods of particle technology are used to model the formation of catalyst precursors with the purpose to control disperse properties. A multi‐component and multi‐phase population balance model is applied to the precipitation of catalyst precursors in a T‐mixer. Copper precursors are chosen to be investigated in detail as a basis for catalysts with a broad range of applications such as in methanol synthesis, water‐gas‐shift and hydrogenation reactions. The simulations results could be validated by ex‐situ measurements such as the pH of the suspension, the solid dry weight of the precipitate and the yield. Simulations show that dissociation reactions of copper and carbonate species in water control significantly the formation of Georgeite. Consumption of the copper component by solid formation can be controlled in a range of 20% to 100% by the adjustment of the pH of the copper nitrate reactant solution. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:13:56.500006-05:
      DOI: 10.1002/aic.14810
       
  • Solvent evaluation for desulfurization and denitrification of gas oil
           using performance and industrial usability indices
    • Authors: Sunil Kumar; Vimal Chandra Srivastava, S.M. Nanoti, Abhishek Kumar
      Abstract: In this paper, a new strategy for screening of solvents for sulfur, nitrogen and aromatic compounds removal from gas oil is presented. This ranking is based on comparative assessment of solvents' capacity, selectivity, performance and newly defined industrial usability index. Twenty eight solvents comprising of six most widely used industrially proven conventional solvents and twenty two imidazolium based ionic liquids solvents were selected to illustrate the strategy. The solvents were ranked for removal of benzothiophene, dibenzothiophene and their alkylated derivatives sulfur compounds, quinoline, indole and carbazole nitrogen compounds from gas oil. Performance index (PI) which combines the effect of both capacity and selectivity seems to be better index than individual capacity and selectivity indexes to rank the solvents. Industrial usability index (SIUI) of solvents which includes PI and process complexity factor of solvent recovery seems more practical and realistic criteria to be used for solvents assessment for a given separation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-27T00:13:36.150343-05:
      DOI: 10.1002/aic.14809
       
  • Rigorous design of distillation columns using surrogate models based on
           kriging interpolation
    • Authors: Natalia Quirante; Juan Javaloyes, José A. Caballero
      Abstract: The economic design of a distillation column or distillation sequences is a challenging problem that has been addressed by superstructure approaches. However, these methods have not been widely used because they lead to mixed‐integer nonlinear programs that are hard to solve, and require complex initialization procedures. In this paper, we propose to address this challenging problem by substituting the distillation columns by kriging‐based surrogate models generated via state of the art distillation models. We study different columns with increasing difficulty, and show that it is possible to get accurate kriging based surrogate models. The optimization strategy ensures that convergence to a local optimum is guaranteed for numerical noise‐free models. For distillation columns (slightly noisy systems), Karush‐Kuhn‐Tucker optimality conditions cannot be tested directly on the actual model, but still we can guarantee a local minimum in a trust region of the surrogate model that contains the actual local minimum. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:25:13.669651-05:
      DOI: 10.1002/aic.14798
       
  • Thermodynamic mechanism of free heme action on sickle cell hemoglobin
           polymerization
    • Authors: Anupam Aich; Weichun Pan, Peter G. Vekilov
      Abstract: For insights into the mechanisms of heme action on the rate of sickle cell hemoglobin polymerization, we determine the erythrocytic concentration of free heme by employing a novel method based on enzymatic catalysis and luminescence. We find in sickle cell patients 44±10 μM, in sickle trait individuals, 33±4 μM, and in healthy adults, 21±2 μM. We test the applicability of two mechanisms of heme action: a kinetic one, whereby heme aggregates serve as heterogeneous nucleation centers, and a thermodynamic pathway, in which free heme enhances the attraction between HbS molecules in solution. We show that the latter mechanism exclusively operates. The enhanced attraction leads to increase of the total volume of a population of dense liquid clusters by about two orders of magnitude. Since the dense liquid clusters serve as locations and precursors to the formation of the HbS polymer nuclei, their increased volume directly leads to faster polymer nucleation. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:25:12.125809-05:
      DOI: 10.1002/aic.14800
       
  • Modeling the permittivity of electrolyte solutions
    • Authors: Jørgen M. Mollerup; Martin P. Breil
      Abstract: Solution of a strong electrolyte in a high‐density polar fluid gives rise to a dielectric saturation that decreases the orientation polarizability of the solvent molecules in close proximity to the ions wherefore the relative permittivity in this region is determined solely by the atomic and electronic polarization. This causes a substantial decrease in the static permittivity of the solution. By considering the dielectric saturation, we have developed a model for the permittivity of an electrolyte solution and determined the parameters, the relative permittivities at dielectric saturation in close proximity to the ions, for 17 ions in water at 298.15K. By scaling these relative permittivities in proportion to the permittivity of the solvent, we were able to extend the model to calculate the permittivity of solutions of electrolytes in methanol and admixtures of water and ethanol. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:25:10.682099-05:
      DOI: 10.1002/aic.14799
       
  • Multiscale modeling of oil uptake in fried products
    • Authors: Jean‐Michaël Vauvre; Anna Patsioura, Régis Kesteloot, Olivier Vitrac
      Abstract: Oil‐air biphasic flow has been simulated at the scale of an entire potato tuber tissue using a Kinetic Monte‐Carlo (KMC) formulation parameterized on microscopic observations. Extrapolations to more general configurations are proposed by combining the proposed KMC framework with oil momentum equations integrated at microscopic scale. Branched percolation routes in 3D honeycomb arrangement of cells are explored using a first‐passage algorithm. Three major applications are presented. KMC simulations are first considered to homogenize sparse dynamic observations at the scale of isolated cells up to the scale of a full tissue. The second application investigates the effect of cell damages on oil uptake. Finally, our general KMC formulation was successfully compared with a diffusive model of oil uptake. Comprehensive rules to set the distribution parameters of all quantities (kinetic and structure parameters) from scarce observations or general assumptions are discussed. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:12:35.302834-05:
      DOI: 10.1002/aic.14801
       
  • Liquid li structure and dynamics: A comparison between OFDFT and second
           nearest‐neighbor embedded‐atom method
    • Authors: Mohan Chen; Joseph R. Vella, Frank H. Stillinger, Emily A. Carter, Athanassios Z. Panagiotopoulos, Pablo G. Debenedetti
      Abstract: The structure and dynamics of liquid lithium are studied using two simulation methods: orbital‐free first‐principles molecular dynamics, which employs orbital‐free density functional theory, and classical molecular dynamics utilizing a second nearest‐neighbor embedded‐atom method potential. The properties studied include the dynamic structure factor, the self‐diffusion coefficient, the dispersion relation, the viscosity, and the bond angle distribution function. We compare simulation results to available experimental data when possible. We find that each method has distinct advantages and disadvantages. For example, orbital‐free density functional theory gives better agreement with experimental dynamic structure factors, yet is more computationally demanding than classical simulations. Classical simulations can access a broader temperature range and longer time scales. We conclude that the combination of first‐principles and classical simulations is a powerful tool for studying properties of liquid lithium. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-21T09:12:32.212563-05:
      DOI: 10.1002/aic.14795
       
  • Issue information
    • Abstract: Top: Layerby‐layer coated nanoparticles designed for dual drug delivery imaged with cryo‐transmission electron microscopy (cryo‐TEM image taken by Erik Dreaden with assistance from Dr. Yun, MIT Koch Institute). Bottom: A degradable PLGA phase inversion membrane with top surface coated with a layer‐by‐layer film containing growth factors to promote bone formation (SEM image taken by Nisarg Shah and Nasim Hyder). 10.1002/aic.14770
      PubDate: 2015-03-18T13:44:18.218456-05:
      DOI: 10.1002/aic.14583
       
  • An old kinetic method for a new polymerization mechanism: Toward
           photochemically mediated ATRP
    • Authors: Yin‐Ning Zhou; Zheng‐Hong Luo
      Abstract: With the idea of “an old method for a new mechanism”, a detailed kinetic insight into photochemically mediated atom transfer radical polymerization (photo ATRP) was presented in this work through a validated comprehensive model. The simulation mimics the experimental results of the model system using optimized photochemically mediated radical generation rate coefficients. The activator and radical (re)generated from the photo‐mediated reactions endow the photo ATRP with unique features, such as rapid ATRP equilibrium and quick consumption of initiator with a small amount of residual. The effect of the reaction parameters on ATRP behaviors was also investigated. Results showed that the acceleration of polymerization rate follows the square root law in the following three cases: the overall photochemically mediated radical generation rate coefficients (kr), the free ligand concentration, and the initiator concentration. However, the independence of the apparent propagation rate coefficient () on the square root of catalyst concentration might be attributed to as the result of the synergy between the activators regenerated by electron‐transfer (ARGET) ATRP and the initiators for continuous activator regeneration (ICAR) ATRP mechanism. The photo ATRP is able to design and prepare various polymers by carefully tuning the conditions using the model‐based optimization approach. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T03:22:25.299832-05:
      DOI: 10.1002/aic.14792
       
  • Designing of anion‐functionalized ionic liquids for efficient
           capture of SO2 from flue gas
    • Authors: Kaihong Chen; Wenjun Lin, Xini Yu, Xiaoyan Luo, Fang Ding, Xi He, Haoran Li, Congmin Wang
      Abstract: Five kinds of anion‐functionalized ionic liquids with different basicity and substituent were selected, prepared and applied in the capture of SO2 from flue gas, where the concentration of SO2 is only 2000 ppm. The effect of the anion on SO2 absorption capacity, desorption residue, and available absorption capacity under 2000 ppm was investigated. The relationship between available absorption capacity and absorption enthalpy was also studied. Through a combination of thermodynamic analysis and quantum calculation, the results indicated that the effect of the cation in the ionic liquid on absorption enthalpy was significant. However, the effect of chain length in the cation was weak. Hence, a new ionic liquid with low molecular weight, [P4442][Tetz], was further designed and applied for the capture of SO2, which shows the high absorption capacity of 0.18g SO2 per g ionic liquid and excellent reversibility for 2000 ppm SO2. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T02:29:15.571995-05:
      DOI: 10.1002/aic.14793
       
  • Experimental and linear analysis for the instability of
           non‐newtonian liquid jets issuing from a pressurized vibrating
           nozzle
    • Authors: C. Rodríguez‐Rivero; E.M.M. Del Valle, M.A. Galán
      Abstract: We analyze experimentally and theoretically the laminar capillary breakup of viscoelastic jets to produce polymeric microcapsules. The phenomenon is based on subjecting a capillary jet to controlled disturbances so that it eventually breaks up forming individual droplets. We obtain a dispersion relation from a temporal linear analysis to describe and predict the system behavior that includes the Oldroyd‐B constitutive equation to take into account the viscoelasticity of the liquid. Dispersion curves relating growth rate and wavenumber of the perturbed jets are compared with experimental conditions and we found that the chosen mathematical approach fairly describes the system. The obtained dispersion relation eases the study of the effect of viscosity, elasticity ‐ through relaxation times ‐ and flow rate in the system. We conclude that the approach allows finding the best conditions to obtain homogeneous droplets and describe qualitatively the system. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T02:28:55.810412-05:
      DOI: 10.1002/aic.14790
       
  • Thermodynamic and kinetic studies of the
           MgCl2‐NH4Cl‐NH3‐H2O system for the production of high
           purity MgO from calcined low grade magnesite
    • Authors: Junfeng Wang; Ah‐Hyung Alissa Park, Camille Petit, Zhibao Li
      Abstract: In order to improve the overall sustainability of MgO‐based refractory production, a novel process to produce high purity MgO from calcined low grade magnesite in ammonium chloride solution was developed. The process was designed on the basis of the phase equilibria of the NH4Cl‐MgCl2‐NH3‐H2O system obtained using the Mixed Solvent Electrolyte (MSE) model embedded in OLI platform. The optimum calcination temperature of low grade magnesite was determined to be 650 °C in terms of the conversion ratio of magnesium and calcium in the leaching experiments. An apparent activation energy of Mg extraction was 30.98 kJ/mol, which is slightly lower than that of Ca leaching. An empirical kinetic model of magnesium extraction was also developed to describe the effects of NH4Cl concentration, particle size of calcined magnesite, and, solid‐to‐liquid ratio on the extent of extraction of magnesium. At leaching time of 10 min, the leachate with high Mg/Ca molar ratio was obtained. Then, MgO with a purity of 99.09% was produced through the decomposition of intermediate 4MgCO3·Mg(OH)2·4H2O. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T02:28:35.833408-05:
      DOI: 10.1002/aic.14789
       
  • A Model for gas transport in micro fractures of shale and tight gas
           reservoirs
    • Authors: Keliu Wu; Xiangfang Li, Chenchen Wang, Wei Yu, Zhangxin Chen
      Abstract: A model for gas transport in micro fractures of shale and tight gas reservoirs is established. Slip flow and Knudsen diffusion are coupled together to describe general gas transport mechanisms, which include continuous flow, slip flow, transitional flow and Knudsen diffusion. The ratios of the intermolecular collision frequency and the molecule‐wall collision frequency to the total collision frequency are defined as the weight coefficients of slip flow and Knudsen diffusion, respectively. The model is validated by molecular simulation results. The results show that: (1) the model can reasonably describe the process of the mass transform of different gas transport mechanisms; (2) fracture geometry significantly impacts gas transport. Under the same fracture aperture, the higher the aspect ratio is, the stronger the gas transport capacity, and this phenomenon is more pronounced in the cases with higher gas pressure and larger fracture aperture. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T02:28:17.000011-05:
      DOI: 10.1002/aic.14791
       
  • Intensification of convective heat transfer in a
           stator‐rotor‐stator spinning disc reactor
    • Authors: M.M. de Beer; J.T.F. Keurentjes, J.C. Schouten, J. van der Schaaf
      Abstract: A stator‐rotor‐stator spinning disc reactor is presented, which aims at intensification of convective heat transfer rates for chemical conversion processes. Single phase fluid‐rotor heat transfer coefficients hr are presented for rotor angular velocities rad s– 1 and volumetric throughflow rates m3s– 1. The values of hr are independent of and increase from 0.9 kWm– 2K– 1 at ω = 0 rad s– 1 to 34 kWm– 2K– 1 at ω = 157 rad s– 1. This is a factor 2‐3 higher than values achievable in passively enhanced reactor‐heat exchangers, due to the 1‐2 orders of magnitude larger specific energy input achievable in the stator‐rotor‐stator spinning disc reactor. Moreover, since hr is independent of , the heat transfer rates are independent of residence time. Together with the high mass transfer rates reported for rotor‐stator spinning disc reactors, this makes the stator‐rotor‐stator spinning disc reactor a promising tool to intensify heat transfer rates for highly exothermal chemical reactions. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-13T02:27:27.582864-05:
      DOI: 10.1002/aic.14788
       
  • Biofuel purification in GME zeolitic–imidazolate frameworks: From ab
           initio calculations to molecular simulations
    • Authors: Kang Zhang; Krishna M. Gupta, Yifei Chen, Jianwen Jiang
      Abstract: A multiscale modeling study is reported on the adsorption of ethanol/water in five zeolitic–imidazolate frameworks (ZIFs) for biofuel purification. The ZIFs (ZIF‐68, ‐69, ‐78, ‐79 and ‐81) have isoreticular GME topology, but differ in organic linkers. The simulated adsorption isotherms of ethanol and water in ZIF‐68 agree fairly well with experimental data. At a low pressure, ZIF‐78 exhibits the highest uptake due to strong hydrogen‐bonding between –NO2 groups and adsorbates. The heats of adsorption at infinite dilution largely follow the trend of binding energies estimated from ab initio calculations. At a high pressure, the uptake is governed primarily by free volume but also affected by hydrogen‐bonding. Among the five ZIFs, ZIF‐79 with hydrophobic –CH3 groups shows the highest adsorptive selectivity for ethanol/water mixtures. This study provides microscopic insights into the adsorption and separation of ethanol/water in ZIFs, and would facilitate the development of new ZIFs for biofuel purification. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-06T18:13:25.542039-05:
      DOI: 10.1002/aic.14787
       
  • Thermodynamic and kinetic studies on alkoxylation of camphene over cation
           exchange resin catalysts
    • Authors: Huiqin Nie; Gaodong Yang, Ruyin Xu, Feng Zhang, Zheng Zhou, Zhibing Zhang
      Abstract: The alkoxylation of camphene with 2‐methyl‐1,3‐propanediol was studied using anhydrous macroporous and strong acid cation exchange resins as catalysts. The effects of various parameters, such as catalyst type, solvent, molar ratio of reactants, reaction temperature and reusability of catalysts, were investigated in a 250mL stirred tank reactor to optimize the reaction conditions. The UNIFAC group contribution method was used to correct liquid nonideality, giving the thermodynamic equilibrium constant at 333‐370K. The enthalpy changes calculated by three different methods (Gaussian 03, constant, a function of temperature) were compared. The value (‐74.63.3 kJ/mol) calculated by the last method was closer to the theoretical value (‐75.73 kJ/mol) than that given by the second method (‐30.21.2 kJ/mol). A Langmuir‐Hinshelwood‐Hougen‐Watson (LHHW) model based on activity was used to fit experimental data and the activation energy was 29.14 kJ/mol. The optimized reaction conditions were also verified in a 5L reaction kettle. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-06T18:01:47.969474-05:
      DOI: 10.1002/aic.14786
       
  • An optimal planning for the reuse of municipal solid waste considering
           economic, environmental and safety objectives
    • Authors: José Ezequiel Santibañez‐Aguilar; Juan Martínez‐Gómez, José María Ponce‐Ortega, Fabricio Nápoles‐Rivera, J. Betzabe González‐Campos, Medardo Serna‐González, Mahmoud M. El‐Halwagi
      Abstract: This paper presents a mathematical programming model for the optimal planning of the reuse of municipal solid waste to maximize the economic benefit while simultaneously considering sustainability and safety criteria. The proposed methodology considers several phases of the supply chain including waste separation, distribution to processing facilities, processing to obtain useful products and distribution of products to consumers. Additionally, the safety criteria are based on the potential fatalities associated with waste management. The proposed optimization model is formulated as a multi‐objective optimization problem, which considers three different objectives including the maximization of the net annual profit, the maximization of the amount of reused municipal solid waste and the minimization of the social risk associated with the supply chain. The proposed model is applied to a case study in the central‐west region of Mexico. The results show the tradeoff between the social risk and the economic and environmental criteria. This article is protected by copyright. All rights reserved.
      PubDate: 2015-03-04T12:01:18.333035-05:
      DOI: 10.1002/aic.14785
       
  • Adaptive model predictive inventory controller for multiproduct batch
           plant
    • Authors: Gyeongbeom Yi; Gintaras V. Reklaitis
      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
      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
      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
      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
       
  • 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
      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
      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
      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
      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
       
  • Mathematical modeling of polyethylene terephthalate (PET) pyrolysis in a
           spouted bed
    • Authors: Arezou Niksiar; Amir Hasan Faramarzi, Morteza Sohrabi
      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
       
  • “Perspective: AIChE 2014 alpha chi sigma award”
    • Authors: Paula T. Hammond; David H. Koch
      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
      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
      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
      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
      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
      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
       
  • John M. Prausnitz: Bridging abstractions and realities
    • Authors: John P. O'Connell
      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
       
  • Suspending a Solid Sphere in Laminar Inertial Liquid Flow –
           Experiments and Simulations
    • Authors: Junyuan Mo; Zhengming Gao, Zhipeng Li, Yuyun Bao, J.J. Derksen
      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
       
  • 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
      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
      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
      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
       
  • Moving ion fronts in mixed ionic‐electronic conducting polymer films
    • Authors: Sarah E. Feicht; George D. Degen, Aditya S. Khair
      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
      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
       
  • 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
      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
       
  • 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
      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
       
  • Modelling and simulation of an industrial‐scale parex process
    • Authors: Marta S. P. Silva; José P. B. Mota, Alírio E. Rodrigues
      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
       
  • On the use of the generalized autocatalytic models: The thermal
           decomposition of 3,5‐dinitro‐4‐methylbenzoic Acid
    • Authors: Roberto Sanchirico
      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
      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
      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
      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
       
  • 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
      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
      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
      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
      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
      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
      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
       
  • Engineering Biomass into Formaldehyde‐free Phenolic Resin for
           Composite Materials
    • Authors: Yongsheng Zhang; Zhongshun Yuan, Chunbao (Charles) Xu
      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
      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
      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
       
  • Multicomponent gas diffusion in non‐uniform tubes
    • Authors: Thomas Veltzke; Lars Kiewidt, Jorg Thöming
      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
      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
       
  • 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: 1263 - 1274
      Abstract: The butyl acrylate synthesis from the esterification reaction of acrylic acid with 1‐butanol in a fixed‐bed adsorptive reactor packed with Amberlyst 15 ion exchange resin was evaluated. Adsorption experiments were carried out with nonreactive 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 behavior of the fixed‐bed adsorptive reactor for the butyl acrylate synthesis. Due to the simultaneous reaction and separation steps, it was possible to obtain a butyl acrylate 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 butyl acrylate synthesis. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1263–1274, 2015
      PubDate: 2014-12-16T13:20:45.066853-05:
      DOI: 10.1002/aic.14701
       
  • Effects of flow history on oil entrapment in porous media: An experimental
           study
    • Authors: Homa Khosravian; Vahid Joekar‐Niasar, Nima Shokri
      Pages: 1385 - 1390
      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 reveal that the residual oil saturation depends on capillary number nonmonotonically. A physically based relationship to scale the capillary desaturation curve is proposed. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1385–1390, 2015
      PubDate: 2014-12-21T00:21:47.031921-05:
      DOI: 10.1002/aic.14708
       
  • A unified theoretical model for breakup of bubbles and droplets in
           turbulent flows
    • Authors: Chutian Xing; Tiefeng Wang, Kunyu Guo, Jinfu Wang
      Pages: 1391 - 1403
      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 was 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 computational fluid dynamics‐population balance model (CFD‐PBM) coupled model to study the hydrodynamic behaviors of a bubble column at elevated pressures. © 2014 American Institute of Chemical Engineers AIChE J, 61: 1391–1403, 2015
      PubDate: 2014-12-21T00:23:46.212511-05:
      DOI: 10.1002/aic.14709
       
 
 
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