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  • One-dimensional model of entrained-flow carbonator for CO2 capture in cement kilns by Calcium looping process
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-21
    Maurizio Spinelli, Isabel Martínez, Matteo C. Romano
    更新日期:2018-06-22
  • Effect of Capillary Pressure Force on Local Liquid Distribution in a Trickle Bed
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-21
    David I.A. Dhanraj, Vivek V. Buwa
    更新日期:2018-06-22
  • Continuous Flow Synthesis of Ultrasmall Gold Nanoparticles in a Microreactor using Trisodium Citrate and their SERS Performance
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-19
    He Huang, Hendrik Du Toit, Maximilian O. Besenhard, Sultan Ben-Jaber, Peter Dobson, Ivan Parkin, Asterios Gavriilidis

    Ultrasmall gold nanoparticles were synthesized without strong capping agents by using a capillary-based continuous flow system. A mixture of gold (III) chloride trihydrate and trisodium citrate flowed through capillaries at elevated temperature. The effect of capillary material (polytetrafluoroethylene, fluorinated ethylene propylene, polyetheretherketone, fused silica), surface-to-volume ratio (capillary internal diameter 0.3-1 mm), average residence time (1.5-30 min) and temperature (70-100 oC) were investigated. At a flow rate of 0.006 ml/min (residence time 30 min), 100 °C, 275 kPa back pressure, citrate/gold molar ratio 3.15 and using PTFE capillary tubing with an inner diameter of 0.3 mm, very small (1.9 ± 0.2 nm) nanoparticles were obtained. For comparison, experiments were also performed under the same experimental conditions, but in slug flow using octane as segmenting fluid, thus isolating the reactants from the tubing wall. The synthesized particles were 17.4 ± 1.4 nm for segmented flow, demonstrating the important effect of the capillary wall surface. The performance of these citrate-capped gold nanoparticles was tested for Surface-Enhanced Raman Scattering (SERS). The average enhancement factor (AEF) of 2 nm gold nanoparticles capped by citrate from our work (AEF = 1.54 × 108) was nearly double when compared to 2 nm phosphate-capped commercial gold nanoparticles (AEF = 7.34 × 107). The adsorption of analyte molecules onto citrate-capped gold surface was easier due to the weaker binding strength of the carboxylate ligand and more hotspots formed with narrower gaps between neighbouring particles, giving rise to improved enhancement.

    更新日期:2018-06-20
  • 更新日期:2018-06-20
  • Development and verification of anisotropic drag closures for filtered Two Fluid Models
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Jan Hendrik Cloete, Schalk Cloete, Federico Municchi, Stefan Radl, Shahriar Amini

    Over the past decade, filtered Two Fluid Models (fTFMs) have emerged as a promising approach for enabling fluidized bed simulations at industrially relevant scales. In these models, the filtered drag force is considered to be the most important quantity that requires closure. To date, such closures have typically relied on an isotropic interphase momentum exchange coefficient by applying a drag correction factor to the microscopic drag closures commonly used in resolved simulations. In the present study, both isotropic and anisotropic closures are developed for predicting the filtered interphase forces. The relative performance of these two approaches is then evaluated by means of an a priori assessment, considering data obtained from simulations in which all flow variables are resolved, which were also used for closure derivation. Also, an a posteriori assessment, which compares coarse grid simulation results to a benchmark resolved simulation of a bubbling fluidized bed, is presented. The primary conclusion from the present study is that it is essential to account for the anisotropy of the filtered momentum exchange coefficient. It is shown that this can be done by employing a drift velocity formulation of the filtered drag force and by considering a gravitational contribution that only acts in the vertical direction. Furthermore, it is found that for the large computational grid sizes that are typically required in industrial scale fluidized bed simulations, a closure for the meso-scale interphase force is essential. Finally, also for coarse grids, a non-linearity correction factor, which accounts for assumptions in deriving the drift velocity-based form of the filtered drag force, requires closure. The present study therefore highlights multiple avenues for improving drag closures used in fTFMs. Hence, these results may critically strengthen the predictive capabilities of fTFMs, as well as guide future modelling efforts.

    更新日期:2018-06-19
  • Measurement of the Residence Time Distribution of a Cohesive Powder in a Flighted Rotary Kiln
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Ingrid J. Paredes, Bereket Yohannes, Heather N. Emady, Fernando J. Muzzio, Al Maglio, William G. Borghard, Benjamin J. Glasser, Alberto M. Cuitiño

    The rotary kiln is an essential device in chemical and metallurgical industries, with applications in a wide range of solids manufacturing processes. In particular, in the preparation of industrial chemical catalysts, the kiln has become a popular reactor for continuous calcination of catalysts ranging from millimeter-sized extrudates to micron-sized powders. As granular and powder flow behaviors are difficult to characterize, the design and scale-up of rotary calcination processes are often performed empirically. The goal of this research is to improve the fundamental understanding of powder flow in rotary kilns to aid in optimization of the continuous calcination process. For successful calcination to occur, the residence time of the particles must exceed the time required for heating and subsequent treatment. For uniform treatment of the feed, the particles must also exhibit low axial dispersion. In this work, the mean residence time and axial dispersion coefficient for a cohesive fluid catalytic cracking powder were determined in a pilot plant kiln by measuring the residence time distribution. This study utilized a pulse test developed by Danckwerts. Results were fit to the Taylor solution of the axial dispersion model and compared to the Sullivan prediction for mean residence time. It was found that the mean resident time decreases as the feed rate, kiln incline, and rotation rate increase. It was also found that the axial dispersion coefficient increases with speed of rotation and angle of incline. However, the axial dispersion coefficient decreases as the feed rate is increased.

    更新日期:2018-06-19
  • Reactive Distillation with Pervaporation Hybrid Configuration for Enhanced Ethyl Levulinate Production
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Felicia Januarlia Novita, Hao-Yeh Lee, Moonyong Lee
    更新日期:2018-06-19
  • In-situ Atomization and Flame Characteristics of Coal Water Slurry in an Impinging Entrained-Flow Gasifier
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Zhicun Xue, Qinghua Guo, Yan Gong, Yifei Wang, Guangsuo Yu

    Based on the bench-scale impinging entrained-flow gasifier with coal water slurry (CWS) as the feedstock and the development of advanced visualization techniques, the in-situ atomization and flame characteristics of CWS were investigated. A new imaging system was applied to capture the images around the burners in the operating condition. After image post-processing, the instantaneous flame, time-averaged flame and oscillation of the flame were discussed. With the statistical method, the droplet size distribution, oscillation of the droplet concentration and time-dependent droplet size were obtained to analyze the efficiency and stability of the atomization process. The instantaneous flame shows that the atomization and gasification process is turbulent. The time-average CWS flame shows that the atomization angle decreases with an increase in the ratio of elemental oxygen to elemental carbon (O/C ratio). The oscillation of the flame and the atomization process demonstrate that in-situ atomization is closely related to the CWS flame. The diameter and number of droplets after primary atomization decrease with the increase of the O/C ratio. The decreases in median diameter and unconsumed CWS rate demonstrate that the increase in O/C ratio improves the efficiency of the atomization process. The reduction in oscillation scopes of the droplet concentration and size demonstrates that the increase in O/C ratio improves the stability of the atomization process. In addition, the droplet concentration c in three different O/C conditions is 17.8 kg·m-3, 5.9 kg·m-3 and 1.6 kg·m-3 which demonstrates that the CWS is the dilute phase in the OMB gasifier.

    更新日期:2018-06-19
  • Discrete Element Method based analysis of mixing and collision dynamics in adhesive mixing process
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Xiaoliang Deng, Kai Zheng, Rajesh N. Davé
    更新日期:2018-06-19
  • A Model for the Formation of Gold Nanoparticles in the Citrate Synthesis Method
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Emmanuel Agunloye, Luca Panariello, Asterios Gavriilidis, Luca Mazzei

    This paper presents a new model for predicting the evolution of the particle size of gold nanoparticles (GNPs) in the citrate synthesis method. In this method, the precursor is an acid solution of tetrachloroauric acid, while the reducing agent is a base solution of sodium citrate. The acid-base properties of the solutions influence how the size of the particles evolves during the synthesis. In the literature, various mechanistic theories have been proposed to explain this evolution. Turkevich et al. (1951), who pioneered this synthesis method, suggested the “organizer theory”. This mechanistic description of the synthesis was modelled by Kumar et al. (2007), but recently Agunloye et al. (2017) showed that in several cases this model performed poorly, since it does not account for the acid-base properties of the reactants. In this work, we present a kinetic model based on the synthesis seed-mediated mechanistic description proposed by Wuithschick et al. (2015). In this description, the precursor concurrently reduces into gold atoms and hydroxylates into a passive form. The gold atoms then aggregate into seed particles, which finally react with the passive form of the precursor in a growth step. We validated the model using experimental data from the literature obtained for conditions in which the seed-mediated mechanism is valid. The predicted GNP final sizes closely agree with those obtained experimentally.

    更新日期:2018-06-19
  • Graphene oxide-modified zinc anode for rechargeable aqueous batteries
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-18
    Zhubo Zhou, Yamin Zhang, Peng Chen, Yutong Wu, Haochen Yang, Haoran Ding, Yi Zhang, Zhongzhen Wang, Xu Du, Nian Liu
    更新日期:2018-06-19
  • Analytical solutions of an isothermal two-dimensional model of a cathode flow channel in a proton exchange membrane fuel cell
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    Aniket U. Thosar, Ashish K. Lele

    Two key assumptions are usually made while deriving analytical solutions of coupled kinetics and transport equations in a single channel on the cathode plate of a proton exchange membrane fuel cell (PEMFC). These are: plug flow and uniform oxygen concentration along the depth of the channel. However these assumptions are not always valid under typical operating conditions of a PEMFC, and particularly so at high current density. In this article we relax these two assumptions and present approximate analytical solutions of the governing equations using the methodology of separation of variables followed by power series solution. Spatial profiles of oxygen concentration and current density were derived, which led to the final derivation of a comprehensive current-potential relationship (polarization curve) in the reaction-controlled regime of an operational PEMFC. We compare polarization curves predicted by the present model with predictions of the earlier analytical model and also with a complete 3D-simulation of the same flow geometry and operation conditions. The local profiles of oxygen concentration and the polarization curve predicted by the present model compare far better with the 3D simulations than the earlier analytical model. While this comparison highlights the importance of the effects of finite oxygen diffusion rate and velocity profile in the channel on the polarization curves, it also points to other important factors that affect the current-potential relation.

    更新日期:2018-06-15
  • A new design method for propeller mixers agitating non-Newtonian fluid flow
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    T. Reviol, S. Kluck, M. Böhle
    更新日期:2018-06-15
  • Quality prediction for multi-grade processes by just-in-time latent variable modeling with integration of common and special features
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    Jingxiang Liu, Tao Liu, Junghui Chen

    To cope with the difficulty of on-line quality prediction for multi-grade processes widely operated in process industries, a just-in-time latent variable modeling method is proposed based on extracting the common and special features of multi-grade processes. Considering the complicated nonlinear characteristics of multi-grade processes encountered in engineering applications, a just-in-time learning (JITL) strategy is developed to choose the relevant samples from different grades with respect to the query sample. A novel common feature extraction algorithm is proposed to determine the common directions shared by different grades of processes. After extracting the common features, a partial least-squares modelling algorithm is used to extract the special directions for each grade, respectively. Hence, product quality prediction can be simply conducted by integrating the common and special parts of each grade for model building in terms of a JITL strategy. A numerical case and an industrial polyethylene process are used to demonstrate the effectiveness and advantage of the proposed method.

    更新日期:2018-06-15
  • Two-step MILP/MINLP approach for the synthesis of large-scale HENs
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    Andreja Nemet, Adeniyi Isafiade, Jiří Jaromír Klemeš, Zdravko Kravanja

    Although different methodologies for the synthesis of heat exchanger network (HEN) problems have been introduced in the last forty years, there are still significant challenges to be addressed, such as solving large-scale problems. This study focuses on synthesizing large-scale HENs using mathematical programming to achieve near globally optimal solutions based on a two-step MILP/MINLP approach. In the first step a mixed-integer linear programming (MILP) model, TransHEN, is used that obtains a globally optimal solution at selected ΔTmin. By utilisation of this model, the most promising matches are selected based on feasibility and viability. The second step entails using the matches selected in the TransHEN of step 1 in a mixed-integer nonlinear programming (MINLP) model, HENsyn, using a reduced superstructure, to generate a feasible HEN. This study presents also a simultaneous Total Site synthesis with direct heat transfer between processes, and is the first step in the wider project of synthesizing an entire Total Site with direct and indirect heat transfer; and is the first step in the wider scope of synthesizing an entire Total Site with direct and indirect heat transfer; however, in order to attain this goal, a tool capable of an appropriately handling large number of streams is required. The newly developed procedure has been tested on several case studies, two of which are presented in this paper. For Case study 1 the results obtained lie within the range of best solutions obtained by other authors. Case study 2, consisting of 173 process stream and involving multiple hot utilities, shows the applicability of the developed method to handle large-scale HEN problems.

    更新日期:2018-06-15
  • Factors Influencing Separation Selectivity of Rare Earth Elements in Flat Sheet Supported Liquid Membranes
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    J. Martínez, R. Rodriguez Varela, K. Forsberg, Å. Rasmuson

    Separation selectivity of the mixture Yttrium-Neodymium-Dysprosium using Bis (2-ethylhexyl) hydrogen phosphate (D2EHPA) as extractant in a flat sheet supported liquid membrane was studied by simulations. A new definition of selectivity and a diffusional-kinetic transient model were used in the calculations. Resistance distribution between the phases, stripping phase pH, extractant concentration and initial feed concentration have great influence on selectivity and process time and their appropriate management would improve separation. The analysis of selectivity using the present model would be a useful tool to design a multistage process aimed at the separation of a multicomponent mixture of rare earth elements into its constituents.

    更新日期:2018-06-15
  • A new compressive scheme to simulate species transfer across fluid interfaces using the Volume-Of-Fluid method
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    Julien Maes, Cyprien Soulaine

    We present a new compressive scheme to simulate species transfer across fluid interfaces using the Volume-Of-Fluid method. We show that at high Péclet numbers, the standard Continuous Species Transfer (CST) generates large numerical diffusion in the phase concentration that can lead to inaccurate simulation of interface exchanges in a two-phase system. To solve this issue, the derivation of the concentration advection flux is revisited. We obtain an additional compressive term in the species concentration equation. This novel approach is labeled Compressive CST approach (C-CST). The method and the input of the compressive term are validated by comparison with analytical solutions of two-phase flow and species transport in a 1D tube. The C-CST approach reduces significantly the numerical errors. Then, the approach is used to investigate and upscale species transfer during drainage in 2D porous media.

    更新日期:2018-06-15
  • Approach for the characterization of industrial process tasks as basis for the generation and application of an equipment module database
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-15
    Martin Eilermann, Alexander Tebbe, Dorothea Schwarz, Stephan Leufke, Christian Bramsiepe, Gerhard Schembecker

    Module-based plant design opens up the opportunity for the (bio-)chemical industry to reduce lead times, which is crucial for future competitiveness. Equipment modules are designed once such that they can cover a wide range of process tasks and conditions. The time-consuming equipment design step is replaced by selecting the most suitable equipment module from an equipment module database so that engineering work is reused. It is the aim of this work to develop a structured approach for the determination of features to characterize industrial process tasks. On the one hand, these characteristic features determined are required for the generation of an equipment module database based on cluster analysis of industrial process tasks (Eilermann et al., 2017). On the other hand, the characteristic features are a measure for similarity of process tasks and support the selection of the same equipment module for similar tasks. Thereby, reuse of engineering is enabled. The approach for the determination of characteristic features presented is based on those used in data mining, whereas the quality of the characteristic features is traded off against the computational effort required. The approach developed is exemplarily applied to industrial liquid/liquid heat exchanger and condenser tasks kindly provided by Evonik.

    更新日期:2018-06-15
  • Mixing of non-Newtonian fluids in a cylindrical stirred vessel equipped with a novel side-entry propeller
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-14
    Peng Wang, Thomas Reviol, Stefan Kluck, Pascal Würtz, Martin Böhle

    A side-entry propeller was designed and introduced in this study. The mixing performance of shear thinning fluids in a cylindrical stirred vessel equipped with this propeller was experimentally investigated via an ultrasonic Doppler anemometer (UDA, experimental results were consistent with theoretical findings. The power number and Reynolds number of this propeller were evaluated by using Chhabra, Metzner and Reed equations. Results showed that the power number versus the Reynolds number curves were highly comparable with Metzner and Reed equations. The velocity jet vectors flow field of 320, 380, and 440 rpm were described in detail. These findings demonstrated that the circulation loops, cavern size, and shape were highly influenced by shear thinning parameters and operating conditions. The average of the velocity profiles from five sample lines in front of the propeller was utilized to analyze the effect of rheological properties and operating conditions on the propeller. The axial, radial and tangential 2D velocity profiles located at one sample line (200 mm) in front of the propeller at the design rotation speed were evaluated.

    更新日期:2018-06-14
  • A Model-Based Approach for Controlling Particle Size Distribution in Combined Cooling-Antisolvent Crystallization Processes
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-13
    N. Ghadipasha, J.A. Romagnoli, S. Tronci, R. Baratti

    This article focuses on the design and implementation of model-based control strategies for real time control of crystal size distribution (CSD) in semi batch crystallization processes. The objective of the feedback controller is to reach a desired particle mean size while the standard deviation is controlled in a feedforward fashion. Alternative model-based control strategies are formulated and implemented for a target mean size. An image processing technique based on wavelet-fractal and energy signature analysis is employed to determine online CSD status for controller corrective actions. To validate the proposed model-based control strategies, unseeded crystallization of sodium chloride in water using ethanol as antisolvent is performed in an experimental bench-scale semi-batch crystallizer.

    更新日期:2018-06-14
  • The dynamics of droplet impact on a heated porous surface
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-13
    P. Zhao, G.K. Hargrave, H.K. Versteeg, C.P. Garner, B.A. Reid, E.J. Long, H. Zhao

    In this paper, droplet impact on a porous surface is experimentally investigated over a wide range of Weber numbers and surface temperatures. Regime transition criteria have been deduced to determine droplet post-impingement behaviour as a function of the Weber number and surface temperature for which a droplet impacting on a porous surface. Based on the energy balance, an analytical model with improved boundary layer description is proposed to predict maximum spreading of droplet following impact on porous surfaces when the effect of heat transfer is negligible. The results of the model indicate that the spreading process after droplet impact on porous surfaces is governed by the viscous dissipation and matric potential. The maximum-spread model predictions agreed well with experimental measurements reported in this paper and the literature over a large range of Weber numbers and different porous surfaces.

    更新日期:2018-06-14
  • Applying image processing methods to study hydrodynamic characteristics in a rectangular spouted bed
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-08
    Jingsi Yang, Ronald W. Breault, Steven L. Rowan
    更新日期:2018-06-08
  • Melt-Front Propagation and Velocity Profiles in Packed Beds of Phase-Change Materials Measured by Magnetic Resonance Imaging
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-07
    Matt E. Skuntz, Dinal Perera, James E. Maneval, Joseph D. Seymour, Ryan Anderson
    更新日期:2018-06-07
  • A four-parameter cubic equation of state for pure compounds and mixtures
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-06
    Pradnya N.P. Ghoderao, Vishwanath H. Dalvi, Mohan Narayan
    更新日期:2018-06-07
  • Prediction of the best cosolvents to solubilise fatty acids in supercritical CO2 using the Hansen solubility theory
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-05
    Diego F. Tirado, María José Tenorio, Albertina Cabañas, Lourdes Calvo

    Cosolvents are employed to improve the extraction efficiency and modify the selectivity of the main solvent. However, choosing a proper cosolvent in supercritical extraction is an arduous task. This study aimed to predict the best cosolvents for the supercritical CO2 extraction of oleic and linoleic acids using the Hansen solubility theory. Calculations were performed for eight organic cosolvents used in food and pharmaceutical production. The best cosolvents for the solubilization of both fatty acids were short-chain alcohols, ethanol and methanol. The predictions were validated with bubble pressures of the mixtures with a 0.003 fatty acid molar fraction at temperatures of 313.2 K and 323.2 K. The experimental results agreed with the predictions. The effect of pressure was well predicted via the direct relationship between pressure and the solvent density. However, the impact of temperature was not properly foreseen because the variation of solute vapour pressure was not considered. The Hansen theory predicted that the miscibility enhancement of the solute in the supercritical mixture is maximum at low pressures and low cosolvent concentrations, as was experimentally confirmed.

    更新日期:2018-06-06
  • Modeling and simulation of CO2 capture in aqueous ammonia with hollow fiber composite membrane contactors using a selective dense layer
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-05
    Villeneuve Kévin, Albarracin Zaidiza David, Roizard Denis, Rode Sabine
    更新日期:2018-06-06
  • NH3-TPD methodology for quantifying hydrothermal aging of Cu/SSZ-13 SCR catalysts
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-05
    Jinyong Luo, Krishna Kamasamudram, Neal Currier, Aleksey Yezerets
    更新日期:2018-06-05
  • 更新日期:2018-06-05
  • Dual effects of water on the performance of copper complex conductive inks for printed electronics
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-04
    Wen Xu, Xiaofeng Dai, Teng Zhang, Tao Wang
    更新日期:2018-06-05
  • Catalytic processing of non-condensable pyrolysis gas from plastics: Effects of calcium supports on nickel-catalyzed decomposition of hydrocarbons and HCl sorption
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-04
    Andrei Veksha, Apostolos Giannis, Wen-Da Oh, Grzegorz Lisak

    Non-condensable pyrolysis gas is a suitable source of hydrocarbons for energy applications. The purpose of this study was to develop a catalytic process for selective decomposition of unsaturated hydrocarbons in the pyrolysis gas as these species compromise the operation of gas engines, gas turbines and fuel cells. The effect of different calcium supports, namely CaCO3, Ca(OH)2, CaO and their mixtures, on the performance of Ni-based catalytic sorbents during the decomposition of hydrocarbons and HCl sorption from non-condensable pyrolysis gas of mixed plastics was investigated. The plastic mixture containing low density polyethylene (40%), polypropylene (40%), polystyrene (10%) and polyvinyl chloride (10%) was initially pyrolyzed at 600 °C producing condensable oils and non-condensable gases. The non-condensable gases were further treated in a subsequent reactor at 700 °C in the presence of catalytic sorbents. All catalytic sorbents were effective for HCl sorption, decreasing the HCl concentration in the gas stream below detectable levels. However, the choice of calcium support had a substantial effect on the catalytic decomposition of hydrocarbons and the properties of produced carbon deposits. CaCO3, Ca(OH)2 and their mixture at 1:1 ratio by mass loaded with Ni showed higher catalytic activity towards the decomposition of hydrocarbons compared to CaO and a mixture containing CaO, CaCO3 and Ca(OH)2 at 1:1:1 ratio by mass. Furthermore, carbon deposits produced on the surface of Ni supported on CaCO3, Ca(OH)2 and their mixture contained multi-walled carbon nanotubes, whereas carbon deposits produced on Ni supported on CaO and the mixture containing CaO had non-filamentous morphology. The observed results can be attributed to the low BET specific surface areas and pore volumes of CaO-containing catalytic sorbents which could limit the dispersion of Ni resulting in low catalytic activity.

    更新日期:2018-06-05
  • Bubbly Flow in Stirred Tanks: Euler-Euler / RANS Modeling
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-04
    Pengyu Shi, Roland Rzehak

    Aerated stirred tanks are frequently used equipment in industries ranging from chemical engineering and biotechnology to minerals processing. In principle, CFD simulation of such equipment on industrial scales is feasible within the Euler-Euler framework of interpenetrating continua. Practical application, however, requires suitable closure models to account for phenomena on the scale of individual bubbles, which are not resolved in this approach. The present work applies a set of closure relations that was previously used with good success to describe bubbly flows in pipes and bubble columns. It turns out that model extensions are needed concerning turbulence and the drag force. To validate the model a comprehensive set of experimental data including gas fraction as well as liquid velocity and turbulence has been assembled from different literature sources. The finally proposed extended model compares reasonably well with this dataset.

    更新日期:2018-06-04
  • Lagrangian modeling of mass transfer from a single bubble rising in stagnant liquid
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-04
    Jannike Solsvik

    A Lagrangian model has been derived that describes the size, species composition and velocity of an individual gas bubble as it ascends through a vertical column with stagnant liquid and exchanges mass with the other phase. Various correlations for the liquid-side mass transfer coefficient for laminar flow have been implemented in the Lagrangian model and the predictions are compared with available experimental data in the literature. The predictability of the Lagrangian model is in general not acceptable due to the limitations of the available theoretical framework employed for deriving the existing correlations for the mass transfer coefficient. The various mass transfer coefficients give very different simulation results, and furthermore, the experimental data show a transient behavior in the change of bubble size due to mass transfer which is not captured by the Lagrangian model. An over- or underestimation of the interface mass transfer flux will give an erroneous change of bubble size, which may have significant influence on the predicted bubble rise velocity - in particular if the drag coefficient is very sensitive to the size of the bubble. It is emphasized that the cause of discrepancy between the simulation results and experimental data is not due to the Lagrangian model but mainly caused by the lack of good models for the mass transfer coefficient.

    更新日期:2018-06-04
  • Quantification of mixing efficiency in turbulent supercritical water hydrothermal reactors
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2011-01-06
    José Sierra-Pallares, Daniele L. Marchisio, Esther Alonso, María Teresa Parra-Santos, Francisco Castro, María José Cocero

    Abstract This paper presents a mathematical model able to quantify mixing efficiency in supercritical water hydrothermal reactors (SWHR) for the production of different types of nanoparticles. In fact, mixing plays a crucial role in determining the final particle size distribution and therefore the final product quality. In this work, mixing of supercritical water streams is studied with Computational Fluid Dynamics (CFD) by using the Reynolds Averaged Navier Stokes (RANS) approach coupled with an equation of state and a micromixing model, to take into account the effect of molecular mixing. The performance of the model is investigated in three different scenarios, corresponding to very different values of the Richardson number and very different mixer configurations. The main results show how mixing can be quantified by means of a global mixing time and how turbulence enhances the process, leading to better final product characteristics, especially in terms of lower mean particle size and narrower particle size distributions. This confirms previous research on this topic, highlighting the fact that both the mean particle size and the particle size distribution are strongly dependent on the mixing features of the SWHR

    更新日期:2018-06-03
  • Structural and kinetic insights into Pt/CNT catalysts during hydrogen generation from ammonia borane
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2017-06-01
    Wenyao Chen, Zijun Wang, Xuezhi Duan, Gang Qian, De Chen, Xinggui Zhou

    Unraveling the structural and kinetic consequences of catalyst properties, which vary with the catalyst preparation methods, on their catalytic behaviors is of prime scientific and industrial importance. Exemplified by Pt/CNT-catalyzed hydrolytic dehydrogenation of ammonia borane (AB), this work examines the origin of the crucial impacts of the catalyst reduction methods (i.e., in situ reduction with AB and ex situ reduction with H2) on the surface and electronic properties of the catalyst as well as the consequent hydrogen generation activity and durability. Kinetic and isotopic analyses reveal that the Pt/CNT-ex situ catalyst has low activation energy and a strong ability to activate water. The relationship between the catalyst structure and performance is established, and the unique surface (e.g., fewer PtO bonds) and electronic properties (e.g., higher Pt binding energy) of the Pt/CNT-ex situ catalyst are deemed to be responsible for the high activity and durability. The insights reported in this work highlight the importance of understanding the preparation-structure-performance relationship to guide the rational design of catalysts.

    更新日期:2018-06-03
  • The Effect of HCl and Steam on Cyclic CO2 Capture Performance in Calcium Looping Systems
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2017-08-14
    Robert T. Symonds, Dennis Y. Lu, Arturo Macchi, Robin W. Hughes, Edward J. Anthony

    Calcium looping is CO2 capture technology that is considered to be technically feasible at an industrial scale using a variety of fuels such as natural gas, coals, biomass, refuse derived fuels, and biofuels. Unfortunately, many of these fuels contain significant quantities of chlorine which principally converts to gaseous HCl during combustion or gasification. To date, very few studies have examined the effect of HCl on sorbent CO2 capture performance using calcium-based sorbents under realistic carbonation and calcination conditions. In this work, experiments were conducted using thermogravimetric analysis and fixed bed reactor testing to determine the effect of HCl addition during carbonation and calcination over repeated cycles using a Canadian limestone. The presence of HCl was found to increase sorbent reactivity towards CO2 capture when steam was injected during calcination. The resulting decomposition of CaCl2 to CaO during calcination caused changes in the particle morphology, which in turn decreased the CO2 diffusional resistance during carbonation. Fixed bed test results provided confirmation of full sorbent dechlorination under typical oxy-fuel calcination conditions. It was shown that both particle surface area and pore volume were higher during tests where HCl was present during carbonation and that greater than 99% HCl capture could be achieved without adversely affecting sorbent CO2 capture performance when steam was present during both carbonation and calcination.

    更新日期:2018-06-03
  • Comment on “Experimental investigation of Taylor vortex photocatalytic reactor for water purification”
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2017-11-13
    Sanjay Mittal, Tayfun E. Tezduyar

    Comment is provided on Dutta and Ray (2004) to identify the source of the two computational-analysis pictures included in the article.

    更新日期:2018-06-03
  • 更新日期:2018-06-03
  • Tungsten carbide hollow spheres flexible for charge separation and transfer for enhanced visible-light-driven photocatalysis
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-01-31
    Yun-Xiang Pan, Hua-Qiang Zhuang, Hui Ma, Jin Cheng, Jie Song
    更新日期:2018-06-03
  • Dynamic behaviors of feed jets and catalyst particles in FCC feed injection zone
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-01-31
    Zihan Yan, Yiping Fan, Xiaotao Bi, Chunxi Lu
    更新日期:2018-06-03
  • Silanol-rich Platelet Silica Modified with Branched Amine for Efficient CO2 Capture
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-02-13
    Xunan Hou, Linzhou Zhuang, Beibei Ma, Shuixia Chen, Hui He, Fengqin Yin
    更新日期:2018-06-03
  • The effect of the Cu+/Cu2+ ratio on the redox reactions by nanoflower CuNiOS catalysts
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-02-15
    Xiaoyun Chen, Dong-Hau Kuo, Albert Daniel Saragih, Zong-Yan Wu, Hairus Abdullah, Jinguo Lin
    更新日期:2018-06-03
  • Hydrogen storage properties of nanoconfined aluminium hydride (AlH3)
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-02-23
    Lei Wang, Aditya Rawal, Kondo-Francois Aguey-Zinsou
    更新日期:2018-06-03
  • Streamline-averaged mass transfer in a circulating drop
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-02-28
    Paul Grassia, Sebastián Ubal
    更新日期:2018-06-03
  • Determination of the interaction mechanism of 10 µm oil-in-water emulsion droplets using optical tweezers
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-03-06
    An Chen, Yu Jing, Fu-Ning Sang, Shao-Wei Li, Jian-Hong Xu
    更新日期:2018-06-03
  • 更新日期:2018-06-03
  • A review on microreactors: Reactor fabrication, design, and cutting-edge applications
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-03-16
    Prashant L. Suryawanshi, Sarang P. Gumfekar, Bharat A. Bhanvase, Shirish H. Sonawane, Makarand S. Pimplapure

    This review focuses on the latest trends and advancements in microstructured reactors. With the recent drive towards the production of miniaturized systems, microstructured reactors have gained significant prominence in the chemical and process industries. Herein, we describe the fabrication, commercial aspects, design principles, and cutting-edge applications of microreactors. An overview of the significant areas of application under broad categories such as biological and pharmaceutical applications, inorganic and noble metal nanoparticles, and organic chemicals and polymers is also included. Finally, the article discusses future research prospects and key issues on microstructured reactors.

    更新日期:2018-06-03
  • Hybrid graphene album with polysulfides adsorption layer for Li-S batteries
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-03-27
    Xiaodong Hong, Ji Liang, Xiaonan Tang, Huicong Yang, Feng Li
    更新日期:2018-06-03
  • Facet design promotes electroreduction of carbon dioxide to carbon monoxide on palladium nanocrystals
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-03-27
    Hao Dong, Lei Zhang, Piaoping Yang, Xiaoxia Chang, Wenjin Zhu, Xiaohong Ren, Zhi-Jian Zhao, Jinlong Gong
    更新日期:2018-06-03
  • Emulsification using a “Sonolator” liquid whistle: a new correlation for droplet size from pilot-scale experiments
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-02
    David J. Ryan, Michael R. Baker, Adam J. Kowalski, Mark J.H. Simmons

    Emulsification experiments have been carried out on a pilot-scale Model ACIP2 Sonolator liquid whistle device by examining the change in droplet size distributions of silicone oil in water emulsions, using SLES as a surfactant, before and after processing. The process variables considered were mass flow rate, pressure drop across Sonolator, oil viscosity (from 10 – 10,000 cSt), oil concentration (0.5 - 10 wt%), surfactant concentration (0.00003-0.5 wt%) and orifice size. All experiments were carried out in the turbulent flow regime. The oil phase was added as either a pure phase or as a pre-emulsion stabilised using SLES. The oil was injected just before the blade or mixed at a T-junction prior to the Sonolator; the pre-emulsion was exclusively introduced via the latter method. The resultant droplet size distributions were obtained from offline sampling using laser diffraction. The most significant parameters found to influence the drop size were found to be pressure drop, dispersed phase viscosity and surfactant (SLES) concentration, which formed the basis for an empirical power law correlation. Indices in this correlation were compared to findings in the literature for other emulsification devices, and to those predicted from the theories of droplet breakage in turbulent inertial flow. Despite an expected regime change from turbulent inertial to turbulent viscous break-up being common in the literature as the dispersed phase viscosity is increased, this phenomenon was not observed in the experimental data obtained, suggesting breakage in an intermediate regime.

    更新日期:2018-06-02
  • Multiphase processes with ionic liquids in microreactors: hydrodynamics, mass transfer and applications
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-02
    Chaoqun Yao, Yuchao Zhao, Guangwen Chen

    Microreaction technology is an important technology for process intensification and high efficient chemical synthesis. The use of ionic liquids (ILs) as novel reaction media is another rapidly developing orientation for process intensification considering their strong dissolubility, low vapor pressure and adaptable physicochemical properties. The combination of the two technologies has been emerging fast in various applications, due to the ability to intensify the utility of ILs in microreactors. This review presents a summary of the recent progress on the transport and reaction processes with ILs in microreactors. A typical characteristic of ILs is their higher viscosity, so the effects of fluid viscosity on the hydrodynamics and mass transfer are highlighted. In addition, new correlations considering both shear and inertial forces are proposed to predict the flow regime transitions in a wide range of fluid viscosity. With respect to mass transfer, the unit cell model for Taylor flow is modified to represent the effect of viscosity on flow topology inside droplets/slugs.

    更新日期:2018-06-02
  • Microwave-assisted fast and efficient dissolution of silkworm silk for constructing fibroin-based biomaterials
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-02
    Shouchuan Li, Chunyu Chen, Di Zhang, Xiaozhong Zhang, Baochang Sun, Shanshan Lv

    A microwave-assisted method was developed for extraction of water-soluble fibroin from silkworm silk. In order to explore enhancing effect of microwave, dissolution profiles of silk fibroin were monitored by protein concentration measurements, showing a faster extraction rate of the microwave-assisted method compared to the conventional methods. Meanwhile, characterization of the resultant silk fibroin regenerated by the microwave-assisted method indicated similarity to that by the conventional methods in that they exhibited similar molecular weight ranges, secondary structures and gelation capabilities. In contrast to traditional microwave-assisted methods, this study employed a laboratory microwave reactor equipped with a feedback temperature control system, which enabled easy control and maintenance of certain reaction temperature and temperature distribution. In this way, the present study, to an extent, resolved possible concerns that uncontrollable extreme high temperature under microwave would cause degradation of the silk fibroin chain. This new microwave-assisted method has demonstrated its advantages of significant reduction in time-consuming and energy cost, and thus stands for a promising economical and efficient method for regeneration of silkworm silk fibroin.

    更新日期:2018-06-02
  • Investigation and Simulation of the Transport of Gas Containing Mercury in Microporous Silica Membranes
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-02
    Guozhao Ji, Anthe George, Vicky Skoulou, Graham Reed, Marcos Millan, Kamel Hooman, Suresh K. Bhatia, João C. Diniz da Costa
    更新日期:2018-06-02
  • Improving particle dispersity and CO2 separation performance of amine-functionalized CAU-1 based mixed matrix membranes with polyethyleneimine-grafting modification
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-02
    Xiangyu Guo, Hongliang Huang, Dahuan Liu, Chongli Zhong

    Poor dispersity of filler particles always limits their application in mixed matrix membranes (MMMs), increasing the difficulties in membrane fabrication and restraining the full exploitation of the intrinsic separation ability of the fillers. Herein, polyethyleneimine (PEI), a functional branched polymer, was covalently bonded on the outer surface of CAU-1 nanoparticles to implement increased colloidal stability and improved CO2 affinity for MMMs preparation. As a result, the dispersity of CAU-1 particles in solvent and MMMs was greatly improved after surface functionalization. Meanwhile, the grafted PEI polymer chains can serve as CO2 carriers simultaneously, which benefits the CO2 transport in MMMs. The prepared MMMs based on modified CAU-1 exhibit largely improved CO2/CH4 separation performance, with a CO2 permeability of 546 Barrer and a CO2/CH4 separation factor of 27.8 at 30 wt% filler loading, showing 165% and 50% increases respectively compared with the pristine polymer membrane. The modification approach presented here is expected to extend the functionality of MOFs and facilitate the development of MMMs.

    更新日期:2018-06-02
  • 更新日期:2018-06-02
  • 更新日期:2018-06-01
  • Fractal analysis of the effect of rough surface morphology on gas slip flow in micro- and nano- porous media
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-01
    Qian Zheng, Jintu Fan, Xiangpeng Li, Chao Xu

    Gas slip flow in micro- and nano- porous media with rough surfaces is investigated by the fractal geometry theory with a focus on the effect of surface roughness of capillaries. Based on the assumption that the pore size distribution of the porous media and rough elements of the wall surfaces of capillaries follow the fractal scaling law, apparent gas permeability and gas slippage factor are derived. According to the Klinkenberg equation, the key to the calculation of apparent gas permeability is the determination of gas slippage factor. In this paper, we established an analytical relationship between the gas slippage factor and the structural parameters of porous media. We first validated the model with available experimental data, then analyzed the effect of the relative roughness, porosity, the tortuosity fractal dimension and the pore fractal dimension on the gas slippage factor. With our fractal model, the physical mechanisms of gas slip flow are better elucidated.

    更新日期:2018-06-01
  • From model compounds to applications: kinetic studies on the activation of dioxygen using an iron complex in a SuperFocus mixer
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-06-01
    Andreas Miska, Daniela Schurr, Günter Rinke, Roland Dittmeyer, Siegfried Schindler

    It was demonstrated previously that a system consisting of a dinuclear iron complex with the ligand HPTB (N,N,N’,N’-tetrakis[2-benzimidazolylmethyl]-1,3-diamino-2-propanol) reacts with dioxygen to form a peroxido complex that may be used for the oxidation of organic substrates. Detailed kinetic studies using stopped-flow techniques and a SuperFocus mixer clearly demonstrate that this complex has a high potential for future applications in catalytic selective oxidation processes in industry. Especially for that reason a reaction KIT system for easy handling was developed that allows to start with a stable iron(III) complex that is reduced (activated) prior to its oxidation with dioxygen.

    更新日期:2018-06-01
  • 更新日期:2018-06-01
  • 更新日期:2018-06-01
  • Simulation of a large methanol-to-olefins fluidized bed reactor with consideration of coke distribution
    Chem. Eng. Sci. (IF 2.895) Pub Date : 2018-05-30
    Jingyuan Zhang, Bona Lu, Feiguo Chen, Hua Li, Mao Ye, Wei Wang
    更新日期:2018-05-31
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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