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  • A novel semi-supervised pre-training strategy for deep networks and its application for quality variable prediction in industrial processes
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-26
    Xiaofeng Yuan; Chen Ou; Yalin Wang; Chunhua Yang; Weihua Gui

    Deep learning-based soft sensor has been a hot topic for quality variable prediction in modern industrial processes. Feature representation with deep learning is the key step to build an accurate and reliable soft sensor model from massive process data. To deal with the limited labeled data and abundant unlabeled data, a semi-supervised pre-training strategy is proposed for deep learning network in this paper, which is based on semi-supervised stacked autoencoder (SS-SAE). For traditional deep networks like SAE, the pre-training procedure is unsupervised and may discard important information in the labeled data. Different from them, SS-SAE automatically adjusts the training strategy according to the given data type. For unlabeled data, it learns the shape of the input distribution layer by layer. While for labeled data, it additionally learns quality-related features with the guidance of quality information. The proposed method is validated on two refining industries of a debutanizer column and a hydrocracking process. The results show that SS-SAE can utilize both labeled and unlabeled data to extract quality-relevant features for soft sensor modeling, which is superior to multi-layer neural network, traditional SAE and DBN.

    更新日期:2020-01-26
  • Axisymmetric granular flow on a bounded conical heap: Kinematics and size segregation
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-24
    Austin B. Isner; Paul B. Umbanhowar; Julio M. Ottino; Richard M. Lueptow
    更新日期:2020-01-24
  • Sustainable Product Design: A Life-Cycle Approach
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-24
    Xiang Zhang; Lei Zhang; Ka Yip Fung; Bhavik R. Bakshi; Ka Ming Ng

    A systematic framework is proposed for sustainable chemical product design. The product technical requirements are first identified as design constraints. Then, a base-case product is generated as a reference on top of which a more sustainable product is designed. To do so, the life cycle of base-case product (in particular, whether and how it should be recycled) is decided by using life cycle sustainability assessment (LCSA) or rule-based methods depending on the availability of life cycle inventory data. In addition, the hotspots (i.e., life cycle stages with major impact) are identified. Afterwards, to reduce the impact on hotspots, product design targets and design alternatives are generated using knowledge-base and heuristics. Lastly, LCSA or rule-based methods is applied to decide the most sustainable product from the generated product design alternatives. Two case studies – composite bumper beam and lithium ion battery – are provided to illustrate the framework.

    更新日期:2020-01-24
  • Kinetic Study of the Toluene Oxidation in Homogeneous Liquid Phase
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-23
    Sebastian Gast; Ute S. Tuttlies; Ulrich Nieken

    To better understand the interplay of fluid dynamics, mass transport, and chemical reactions in multi-phase reactors, each of these effects needs to be studied separately. In particular, reactions are hard to study separately from mass transport. In this work, using a new reactor concept a macroscopic reaction kinetics of the oxidation of toluene is determined in homogeneous liquid-phase. By operating at elevated pressure, mass transport limitations are avoided. The reactor concept requires the measurement of the oxygen concentration within the organic liquid phase, which further allows to setup an atomic oxygen balance. Running experiments at different oxygen flow rates, a kinetic model was parameterized, which describes the experimental results for oxygen flow rates in an industrially relevant range. Since the developed model has no mass transport limitations, it can be used in processes where independent modelling of mass transport and chemical reactions are combined, such as with computational fluid dynamics.

    更新日期:2020-01-23
  • Numerical Simulation of a 3D Full Loop iG-CLC System Including a Two-Stage Counter-Flow Moving Bed Air Reactor
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-22
    Yali Shao; Ramesh K. Agarwal; Xudong Wang; Baosheng Jin

    A three-dimensional two-fluid model is established for an in-situ gasification chemical looping combustion system to predict its dynamic characteristics and non-uniformity in gas-solid distribution. In the experiment, the fuel reactor (FR) and air reactor (AR) were designed as a high-velocity riser and a novel low-velocity moving bed, respectively. Simulations results show that the predicted pressure distributions agree reasonably well with the experimental data. AR operation did not show any obvious influence on oscillations in the full-loop particle circulation. Each stage of the moving bed AR is found to operate better at relatively lower gas fluidizing number, and the maximum allowable fluidizing number is estimated to be around 0.7. With increase in fluidizing number in AR, gas concentration, gas velocity and solid velocity uniformity index increase, while solid concentration uniformity index decreases. Compared to the parallel arrangement of gas distributors and exhausts, gas concentration and velocity uniformity indices are smaller except for the near-exhaust section under the vertical arrangement of gas distributors and exhausts. Increase in first-stage or second-stage AR outlet pressure has an opposite influence on gas leakage in both the first-stage AR and second-stage AR.

    更新日期:2020-01-22
  • Process of particles flow across staggered tubes in moving bed
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-21
    Shengan Deng; Zhi Wen; Guofeng Lou; Dengyu Zhang; Fuyong Su; Xunliang Liu; Ruifeng Dou
    更新日期:2020-01-22
  • Numerical investigation of the effect of three-dimensional modified parallel flow field designs on proton exchange membrane fuel cell performance
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-21
    B.H. Lim; E.H. Majlan; W.R.W. Daud; M.I. Rosli; T. Husaini

    Uneven flow resistance can cause a cell to have uneven distributions of temperature and current density. In this study, a three-dimensional (3-D) model with modified parallel flow field patterns is constructed, and simulation is performed to study the reactant distribution and cell performance. Two different modified parallel flow fields are applied to the cathode and anode. The flow characteristics and current density, temperature, and water distributions are analyzed with computational fluid dynamics (CFD). The results indicate that the hydrogen and air reactants are uniformly distributed in a gas diffusion layer (GDL) and gradually decrease from the inlet to the outlet for all channels. The numerical results show that modified parallel flow fields provide evenly distributed current density generation, where the reactant is uniformly distributed in the flow field. This property reduced the likelihood of forming hot spots and consequently enhanced the PEMFC performance.

    更新日期:2020-01-22
  • Identification of Gas-Liquid Two-Phase Flow Patterns in Dust Scrubber based on Wavelet Energy Entropy and Recurrence Analysis Characteristics
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-21
    Tao Wei; Xiaochuan Li; Dongxue Wang

    For a wet dust scrubber, dust collection efficiency is tightly connected with the gas-liquid two-phase flow pattern. Using the characteristic parameters selected by current flow pattern identification methods, regions of significant coincidence exist among different patterns, thereby leading to a decline in the identification efficiency. In this study, a new method for processing the wavelet decomposition signal of the dust collector pressure was proposed to obtain the characteristic parameters that distinguish the flow pattern. Firstly, detailed information regarding the different frequency bands of the pressure signal was extracted via wavelet analysis. Then, in combination with the information entropy theory, wavelet energy entropy (WEE) was proposed to evaluate the uniformity of energy distribution in different frequency bands. The results show that WEE is sensitive to the change in gas-liquid two-phase flow patterns, and the corresponding distinguishing efficiency of flow patterns is 92.5%. There was only a small amount of crossover between the shear liquid curtain and entrainment air bubble pattern. For this, using the recursive analysis method (RAM), the characteristic recurrence plots (RP) and recurrence quantification analysis (RQA) of the original pressure signals and the wavelet decomposition signal with different frequency bands were obtained. Results show that the RP characteristics can intuitively reflect the gas-liquid flow state of different flow patterns. Although RQA characteristics are not sensitive to the change in low-level gas/liquid resonance flow pattern in the dust scrubber, it exhibits strong distinction to the evolution of other flow patterns. It effectively compensates for the crossover at the flow pattern distinguish between the shear liquid curtain and entrainment of air bubble using the parameters of the wavelet energy entropy. It is the highlight of this article that the combination of WEE and recurrence characteristics can effectively address the problems of high coincidence of flow pattern features in the dust scrubber.

    更新日期:2020-01-22
  • Application of Machine Learning Methods to Understand and Predict Circulating Fluidized Bed Riser Flow Characteristics
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-21
    Jia Wei Chew; Ray A. Cocco

    Machine learning methods were applied to circulating fluidized bed (CFB) riser data. The goals were to (i) provide insights on various fluidization phenomena through determining the relative dominance of the process variables, and (ii) develop a model to provide predictive capability in the absence of first-principles understanding that remains elusive. The Random Forest results indicate radial position had the most dominant influence on local mass flux and species segregation, overall mass flux was the most dominant for local particle concentration, while no variable was particularly dominant or negligible for the local clustering characteristics. Furthermore, the Neural Network can be trained to provide good predictive capability without any mechanistic understanding needed if a sufficiently large dataset is used for training and if the input variables fully account for all the effects at play. This study underscores the value of machine learning methods in fluidization to advance understanding and provide adequate predictions.

    更新日期:2020-01-22
  • Development and confirmation of a simple procedure to measure solids distribution in fluidized beds using tracer particles
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-21
    Yupeng Xu; Tingwen Li; Liqiang Lu; Xi Gao; Sina Tebianian; John R. Grace; Jamal Chaouki; Thomas W. Leadbeater; Rouzbeh Jafari; David J. Parker; Jonathan Seville; Naoko Ellis

    The spatial distribution of solid particles is a key factor affecting the performance of fluidized bed reactors. Non-invasive techniques including radioactive particle tracking (RPT) and positron emission particle tracking (PEPT) are deployed to measure the solids distribution. Different methods to calibrate the particle tracking measurements have been developed to quantify mean solids concentration. In this paper, gas-solid flows in a traveling fluidized bed are simulated with CFD-DEM and the behavior of different particles, including bulk sand particles and tracer particles are investigated. The simulated hydrodynamics are compared with experimental measurements. Analyses are carried out to derive the mean solids concentration from the tracer particle data. Different calibration approaches are examined, and the simple calibration method is verified. It is shown that the mean solids concentration can be measured reliably using representative tracer particles. The experimental RPT data are then revisited with the new calibration method which yields more realistic results.

    更新日期:2020-01-22
  • Preparation of Microdispersed Droplets by Phase Inversion in Gas/Liquid/Liquid Microdispersion System
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-20
    Ya-Ni Ji; Wen-Jie Geng; Chun-Yang Ma; Jing Tan; Wen-Sheng Deng; Bin Liu; Yue-Feng Su
    更新日期:2020-01-21
  • Equivalent permeability of shale rocks: Simple and accurate empirical coupling of organic and inorganic matter
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-19
    Jiangfeng Cui; Keliu Wu

    Coupling the organic/inorganic permeabilities in shale is fundamental. Simple treatments, including the arithmetic/geometric average methods, are problematic and can lead to large errors. More complicated methods can generate reasonable results but are much more expensive. In this work, a simple and accurate empirical model for the equivalent permeability of shale considering permeability contrast between organic and inorganic matter and TOC is established. Geometric explanation of the parameters in the model is also provided. Afterwards, model validation against numerical data demonstrates the accuracy of the model in all realistic scenarios. Moreover, model comparison with arithmetic/geometric average methods shows the superiority of the model in accurate calculation while keeping the form simple. Finally, the model is applied to liquid flow in shale, and the results are analyzed. The model is highly recommended for theoretical studies in shale gas/oil that need coupling of the organic and inorganic permeabilities, including single-phase and multi-phase flows.

    更新日期:2020-01-21
  • Potential of flotation as alternative separation process in biotechnology with focus on cost and energy efficiency
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-18
    S.J. Gulden; C. Riedele; M.-H. Kopf; H. Nirschl

    Flotation is a density separation process which is influenced by physico-chemical interaction between a particle and a bubble. In biotechnology, it finds application in the solid-liquid separation of biomass. The process mechanism depends on the formation of stable microorganism-bubble-complexes by collision and adsorption. The difference in density of these complexes and the surrounding liquid medium causes them to rise to the liquid surface, where a foam develops. This microorganism enriched foam can then be removed. An economical comparison of the separation technologies centrifugation, cross-flow-filtration and flotation showed, that flotation is a financially and energetically interesting alternative process step for the harvest of microorganisms. In this work separation results with a model microorganism S. cerevisiae are presented. Experiments were conducted batch-wise in a 6L- laboratory dissolved air flotation setup, where bubble generation classically results from expanding air from supersaturated medium. Goal was the optimization of the flotation rate and the energy efficiency of the flotation process by adaptation of operational parameters, such as gas- and recycle flow rate and saturation pressure. Flotation models show proportional dependency between the flotation rate and the bubble size and bubble surface area flow rate. Therefore, the effect of operational parameters, such as saturation pressure, recycle and gas flow rate, on the bubble size and surface area flow rate was analyzed. The positive effect of an increasing bubble surface area was possible with increasing gas flow rate, recycle flow rate and saturation pressure. Decreasing bubble sizes were measured for increasing recycle flow rate and saturation pressure, meanwhile the contrary was the case with an increasing gas flow rate. Evaluation of the flotation rate and flotation energy efficiency showed, increasing the recycle flow rate and the saturation pressure both improved the flotation rate, but had low effect on the energy efficiency. Increasing the gas flow rate improved both flotation rate and energy efficiency. It is the most interesting operational parameter for enhancing the process efficacy.

    更新日期:2020-01-21
  • Incorporating nano-sized ZIF-67 to enhance selectivity of polymers of intrinsic microporosity membranes for biogas upgrading
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-17
    Chumei Ye; Xingyu Wu; Hong Wu; Leixin Yang; Yanxiong Ren; Yingzhen Wu; Yutao Liu; Zheyuan Guo; Rui Zhao; Zhongyi Jiang
    更新日期:2020-01-17
  • Dual-conductive N,S co-doped carbon nanoflowers for high-loading quasi-solid-state supercapacitor
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-17
    Ling Chen; Cheng Lian; Hao Jiang; Lingxue Chen; Jian Yan; Honglai Liu; Chunzhong Li

    To cope the challenges including the low areal energy density and interface engineering between electrode and electrolyte of quasi-solid-state supercapacitors. We herein demonstrate the rational design and synthesis of ion/electron dual-conductive carbon nanoflowers assembled by N,S co-doped two-dimension mesoporous nanosheets. Electronic density functional theory calculations suggest that the S doping could lead to an extra quantum capacitance and suppress the side reactions. The structure characterization suggests that the bigger S atoms could enlarge interlayer distance of carbon from 0.347 nm to 0.378 nm, accelerating ions diffusion kinetics. Consequently, the N,S-C nanoflowers deliver excellent electrochemical performances even the loading mass of N,S-C reaches 6.38 mg cm-2 owing to the good electrical conductivity and low charge transfer resistance. Furthermore, the a symmetrical quasi-solid-state supercapacitor is assembled and delivers a high specific capacitance of 52.5 F g-1 even at 13.5 mg cm-2 and a capacitance retention of 97.2% after 10000 cycles.

    更新日期:2020-01-17
  • 更新日期:2020-01-15
  • Prediction of gas holdup in partially aerated bubble columns using an EE-LES coupled model
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-14
    S.J. Zhu; A. Ooi; R. Manasseh; A. Skvortsov

    Transient gas-liquid flow dynamics in partially aerated square cross-sectioned bubble columns were studied using an Eulerian-Eulerian based large eddy simulation approach. The numerical model was validated with the interfacial closures evaluated for drag, lift and virtual mass forces. The simulation data showed good agreement with both numerical predictions and experimental measurements in the literature. The current model was also shown to be able to predict the global gas holdup in the bubble column up to a very high value. Further simulations were performed to study the influences of initial liquid phase height to width ratio and inlet area to column cross-sectional area ratio on the global gas holdup in the bubble column. The numerical results indicated that the global gas holdup increases linearly with the superficial gas velocity. Thus, an empirical multivariate regression model was proposed to predict the global gas holdup with an adjusted R-square value of 0.99.

    更新日期:2020-01-14
  • Experimental Study on Millimeter-scale W1/O/W2 Compound Droplets Formation in a Co-flowing Device with Two-step Structure
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-13
    Dawei Pan; Qiang Chen; Shufan Chen; Bo Li

    W1/O/W2 compound droplets generation in a co-flowing microfluidic device with two-step structure was observed through experiments, and the formation process is quantitatively studied. Further the effects of the flow rates of all phases as well as the viscosity of W2 phase on the geometric size are extensively investigated. The results indicate that the outer diameter of compound droplets mainly depends on the flow rate and viscosity of external phase. The core water droplet diameter can be controlled by adjusting the flow rates of both inner and middle phases, and it is more sensitive to inner phase. Generally, the inner diameter of compound droplets is not only relative to the core droplet diameter, but also influenced by the encapsulated core water droplet number. Finally, a prediction correlation for dimensionless outer diameter with several dimensionless numbers is obtained. The results could provide an experimental basis for controllably preparing millimeter-scale monodisperse compound droplets.

    更新日期:2020-01-14
  • 更新日期:2020-01-14
  • 更新日期:2020-01-13
  • A semi-empirical method to quantify the impact of mass transfer on lab-scale SCR deNOx catalyst activity testing
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-10
    J. Blondeau; T. Coppieters; F.A.G. Mercier

    Industrial denitrification catalyst monoliths are regularly tested in controlled lab-scale conditions to quantify their activity. As mass transfer phenomena occurring inside the channels of the monoliths have an important impact on the global denitrification kinetics, activity measurements must be conducted in well-known conditions in terms of sample geometry and gaseous flow regimes, among others. The lack of accurate mass transfer correlations for the complex flows at stake however prevents any accurate generalisation of the test results. In this paper, we propose a semi-empirical method for the quantification of contribution of mass transfer to the global denitrification kinetics for any given test bench. It is based on the experimental adjustment of mass transfer correlations presenting a suitable form. Mass transfer can therefore be decoupled from the intrinsic kinetics and large ranges of conditions can be covered by conducting a limited number of measurements.

    更新日期:2020-01-10
  • Dimensional-Analysis and Similitude for Scale-up of Solid-Liquid Extraction of Eurycoma Longifolia Roots
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-10
    Noor Hafiza Harun; Azila Abdul-Aziz; Roshanida A. Rahman; Harisun Yaakub; Ramlan Aziz; Ismail Ware
    更新日期:2020-01-10
  • Population balance modelling of aggregation of monoclonal antibody based therapeutic proteins
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-09
    Rohit Bansal; Pulkit Srivastava; Anurag S. Rathore; Paresh Chokshi

    Monoclonal antibodies (mAbs) are one of the most important class of therapeutic proteins. Their proteinaceous nature makes them labile towards aggregation, considered a critical quality attribute (CQA) as it affects safety and efficacy of a biotherapeutic product. Present study examines early stage aggregation behaviour of monoclonal antibodies experimentally. The process is also described using hybrid reaction and population balance model. Size exclusion chromatography and dynamic light scattering have been used to obtain kinetic parameters featuring in the mechanistic model. The aggregation process of two different mAbs in the presence of either acetate or citrate buffer is analysed at two temperatures. The rate of aggregation is found to be significantly influenced by the type of buffer medium (faster in citrate compared to acetate buffer). The enhanced aggregation in citrate buffer is attributed to the reduction in the net energy barrier for protein-protein interaction resulting in loss of stability of mAb species.

    更新日期:2020-01-09
  • Fabrication of highly efficient thermal energy storage composite from waste polystyrenes
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-08
    Changhui Liu; Xiaotian Ma; Peixing Du; Zhonghao Rao

    To high value-added utilization of waste polystyrene (PS) foam, an in-situ phase change material (PCM) encapsulation protocol was realized by using waste PS foam as a holding material for thermal energy storage with a shape-stabilization methodology. Mechanistic study suggested that the robust Lewis acid catalysed Friedel-Crafts reaction involved was the key to the success of this method owing to a simultaneous process of porous structure formation and PCM impregnation, by which the PCM encapsulation rate can attain to 68.7% without leakage. Lewis acid catalysts used in the process were able to be converted to their corresponding metal oxides via a simple alkali treatment, which not only diminished the tedious metal species isolation step but also made an external thermal conductivity enhancement that an utmost 61.0% thermal conductivity enhancement can be achieved compared with that of pristine paraffin wax. Additionally, the PCM composite preparation process can be facilely scaled up which strongly demonstrated its real application feasibility. Moreover, besides waste PS foam, other waste PS based materials were proven to be feasible towards PCM holding materials with the same approach.

    更新日期:2020-01-09
  • 更新日期:2020-01-08
  • Viscosity of molten CaO-K2O-SiO2 woody biomass ash slags in relation to structural characteristics from molecular dynamics simulation
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Charlie Ma; Nils Skoglund; Markus Carlborg; Markus Broström

    Molten compositions in the CaO-K2O-SiO2 system relevant to woody biomass ash slags were simulated with molecular dynamics to extract structural characteristics. Multivariate analysis elucidated correlations of these structural characteristics with viscosity measurements. The simulations show SiO4/silicate tetrahedral units (STUs) diffusing slowly and forming flexible networks via oxygen bridges. The degree of STU polymerization varies linearly with the (K2O + CaO)/SiO2 ratio. Ca depolymerises stronger than K, but K diffuses quicker. Depolymerization and diffusion cause network disruptions and agitations that promote collective atomic mobility of the system. This imposes structural characteristics in the slag that correlate with viscosity. The inter-STU Si-O-Si angle narrows with decreasing viscosity, while the Si-O bond length of these bridges increases. Attributes related to atomic mobility, such as the variations in the Si-O-Si angle and the distance of nearest Si–Si pairs, also correlate with viscosity. The discussion provides insight into the connection between structural characteristics and viscosity.

    更新日期:2020-01-07
  • BubCNN: Bubble detection using Faster RCNN and shape regression network
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Tim Haas; Christian Schubert; Moritz Eickhoff; Herbert Pfeifer
    更新日期:2020-01-07
  • Aggregating Thermodynamic Behavior of Amphiphilic Modified Xanthan Gum in Aqueous Solution and Oil-flooding Properties for Enhanced Oil Recovery
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Jingjing Huang; Chuanrong Zhong; Yan Yang

    Novel chloride-substituted octylphenoxy polyoxyethylene (COP20, polymerization degree: 20) was synthesized. Xanthan gum (XG) was then modified by using COP20 to produce XGP20. XGP20 could be expected to be applied in polymer flooding. Compared with XG, the XGP20 solutions exhibited lower interfacial tensions in additional to higher apparent viscosities and salt-thickening effect. Its critical micelle concentrations (CMC) were 0.3 g/L in water and 5 g/L NaCl at 30 °C, and the interface tension was 0.46 mN/m in the saline solution. Large associating structures formed in the XGP20 saline solution. The thermodynamic data of micellization revealed that the micelle formations were spontaneous from 30 to 50 °C. Both standard enthalpy and entropy increased clearly with temperature. Compared with XG, the resistance and residual resistance factors were evidently higher in 5.177 g/L salt for XGP20. Nuclear magnetic resonance images showed that the sweep efficiency of water was enhanced significantly after XGP20 polymer flooding.

    更新日期:2020-01-07
  • The War on Liquids: Disintegration and Reaction by Enhanced Pulsed Blasting
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Wayne Strasser

    Under certain conditions in preferred three-stream geometries, a non-Newtonian airblast atomization flowfield violently pulses (axially and radially) by self-generating and self-sustaining interfacial instability mechanisms. The pulsing is severe enough to send acoustic waves throughout feed piping networks. The most recent work on this system instructed that exothermic chemical reactions enhance this moderate Mach number atomization. Explored herein is the potential to further enhance reaction-assisted disintegration by independently superimposing both sinusoidal and randomized mass flow fluctuations of +/- 50% of the mean onto otherwise constant gas feed streams using surrogate models. Two nozzle geometries (low versus high prefilming distance) and multiple superimposed feed frequencies (ranging from below to above the naturally dominant tone) are considered for each gas stream, making twenty-one total long-running unsteady PLIC-VOF CFD models. Droplet size, plus nine other temporal measures, were considered for assessing atomizer performance in our energy production process. Results indicate that superimposed frequencies have potential to enhance chaotic atomization in a statistically significant manner. Depending on the geometry, the largest effect was about a 10% reduction in droplet size; however, some combinations experienced a droplet size increase. Only marginal differences were seen in the nine other measures, such as injector face heat exposure. In addition to the immediate industrial benefit from modulation, dramatic changes in acoustics were produced by imposed feed perturbations at frequencies lower than the natural tone. A detailed study of start-up flow reveals new mechanisms which explain performance differences.

    更新日期:2020-01-07
  • Gas-solid fluidized bed simulations using the filtered approach: Validation against pilot-scale experiments
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Wenchao Yu; Pascal Fede; Mahdi Yazdanpanah; Benjamin Amblard; Florian Euzenat; Olivier Simonin
    更新日期:2020-01-07
  • Gas-solid heat transfer in assemblies of cubes for ReV≤100
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-07
    Y. Chen; C.R. Müller
    更新日期:2020-01-07
  • Role of Salts in Performance of Foam Stabilized with Sodium Dodecyl Sulfate
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-03
    Ning Jiang; Xiaoyang Yu; Youjie Sheng; Ruowen Zong; Changhai Li; Shouxiang Lu

    Surface activity, foaming ability, and foam stability of SDS and salts mixtures are experimentally studied. It is shown that adding KCl or CaCl2 can increase the surface activity but decrease the foaming ability of SDS solution. The capacity to stabilize SDS foam decreases as KCl>CaCl2>NaCl. The SDS foam ageing is delayed due to the crystals blocked in the plateau borders and adsorbed on the surface of bubble films. When the SDS concentration is too high, the foam stability rises only if there are enough crystals in the plateau borders. The influence of crystal structure on foam stability has been investigated by using FESEM. The KDS crystals with lower random close-packing density stabilize SDS foam more efficiently than Ca(DS)2 crystals with higher random close-packing density. The understanding of this study is of great importance for the application of SDS foams in fire extinguishing and upstream petroleum industry.

    更新日期:2020-01-04
  • 更新日期:2020-01-04
  • Non–Decay of Complex Scalar Field Fluctuations in Isotropic Turbulence
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-03
    S. Wattananusorn

    In this paper two things are done. (1) It is shown that the concept of a direct energy cascade is possible to be violated under specific circumstances as a consequence of dissipation process which initially takes place at Taylor microscales of the inertial subrange. (2) This work predicts, for the first time, the existence of isotropic turbulence at length scales smaller than that of Kolmogorov scales and that it never decays with time as long as the fluid is in motion. It should be remarked that no comparison with experiments searching for the proposed length scales can be made at present.

    更新日期:2020-01-04
  • Breakup dynamics of low-density gas and liquid interface during Taylor bubble formation in a microchannel flow-focusing device
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-03
    Xingchen Li; Yiyong Huang; Xiaoqian Chen; Zan Wu

    This work aims to investigate the breakup dynamics of the low-density gas and liquid interface during bubble formation in a microchannel flow-focusing device. A high-contrast interface tracking method is developed. After the neck motion analysis in radial and axial directions, the time domain criterion between the liquid squeezing stage and the free pinch-off stage is proved to be two orders of magnitude less than the capillary time and is close to the viscous time of the liquid. Comparing to Nitrogen bubbles, the pinch-off point of Helium bubbles deflects downstream in viscous liquids and upstream in low surface tension liquids. Helium bubbles generate faster in viscous liquids and slower in low surface tension liquids. The power law exponents of thread diameter to the pinch-off remaining time in Helium experiments, which are larger than those in Nitrogen experiments, agree with previous studies in both ranges (1/3 to 1/2) and tendency.

    更新日期:2020-01-04
  • Roll-to roll Initiated Chemical Vapor Deposition of Super Hydrophobic Thin Films on Large-Scale Flexible Substrates
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-02
    Hüseyin Şakalak; Kurtuluş Yılmaz; Mehmet Gürsoy; Mustafa Karaman
    更新日期:2020-01-02
  • 更新日期:2020-01-02
  • Efficacy of Antifreeze Proteins from Clupea harangues and Anarhichas minor on Gas Hydrate Inhibition via Cell Surface Display
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-02
    Songlee Han; Murali Kannan Maruthamuthu; Wonhee Lee; Soon Ho Hong; Seong-Pil Kang
    更新日期:2020-01-02
  • Mechanism of surface morphology evolution in the reduction of fine iron ore in a conical fluidized bed reactor
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2020-01-02
    Xu Zhang; Shengyi He; Haoyan Sun; Qingshan Zhu; Jun Li; Hongzhong Li
    更新日期:2020-01-02
  • A Novel Bayesian Optimization for Flow Condensation Enhancement using Nanorefrigerant: A Combined Analytical and Experimental Study
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-31
    Behnoush Rezaeianjouybari; M. Sheikholeslami; Ahmad Shafee; Houman Babazadeh

    According to the recent researches, adding nanomaterial within the pure refrigerant can substantially enhance the heat transfer rate in phase change (boiling/condensing) flows. Therefore, for a given operating conditions, it is unclear whether the heat transfer is optimized at a certain mass fraction of nanoparticles. In the present study, an integrated analytical, and experimental approach was scrutinized to find the heat transfer optimization of flow condensation using nanorefrigerant. For the experiment, CuO nanoparticles were disperesed with varying mass fractions (0.5–3.5%) in the baseline refrigerant/oil (R600a/POE) to produce Nanorefrigerants (R600a/POE/CuO). The optimum nanomaterial concentration for maximum perfromance has been desiganted by a novel optimization method called two stage-Bayesian optimization (TS-BO), which replaces the expensive experimental process by a cheap surrogate model constructed by Kriging. It was proved that the optimum nanoparticle fraction is significantly depend on the mass velocity and vapor quality while at a fixed vapor quality, the optimum nanoparticle concentration increased with decreasing mass flux. The highest heat transfer enhancement was achieved by nanparticle concentrations of 1.5–2.2%.

    更新日期:2019-12-31
  • Energy–efficient mixing generated by prescribed crosswise oscillations of a square prism in highly confined flows
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-30
    A. Valeije; F. Sastre; E. Martín; A. Velázquez

    Mixing downstream of a moving square cylinder placed inside a square section channel was analyzed experimentally and numerically at blockage ratio 2/5 and Reynolds 200. Three frequencies were considered for the prescribed sinusoidal, constant amplitude, cylinder motion: 0.5f0,1f0 and 2f0, where f0 stands for the frequency of the first instability of the wake in the unmoving cylinder case. Mixing was quantified by computing the downstream standard deviation of the distribution of virtual particles seeded behind the cylinder. Experimental PIV frames were used to evaluate mixing at the channel symmetry plane. Numerical streak-lines were used to compute mixing at the full section of the channel. The power required to move the cylinder was computed as well. It was found that maximum mixing efficiency combined with minimum motion power occurred for the frequency 1f0, proving that optimum mixing does not necessarily require high frequencies and/or high input power.

    更新日期:2019-12-30
  • Dynamic optimization of natural gas pipeline networks with demand and composition uncertainty
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-29
    Kai Liu; Lorenz T. Biegler; Bingjian Zhang; Qinglin Chen

    Pipelines are one of the most efficient methods to transport large quantities of natural gas from gas reserves to main markets. However, because of the unsteady nature of gas flow, the operation of pipelines is always dynamic. Furthermore, the uncertainties in demand and the fluctuation of gas composition also make the efficient operation of these dynamic processes challenging. This study addresses the problem of determining the optimal operation to minimize compression costs, while considering demand and gas composition uncertainties. A dynamic pipeline network model is developed with rigorous thermodynamic equations, allowing accurate calculation of gas compressibility factor at any temporal and spatial point. The supply gas composition and demand nodes flow rates are assumed to be uncertain. To deal with these uncertainties, a robust optimization algorithm is applied using back-off constraints calculated from Monte Carlo simulation. Through successive iterations, the algorithm terminates at a solution that is robust to a specified level of process variability with minimal cost. We show from the case studies that the formulated model and the algorithm can successfully address the problem with acceptable computational cost.

    更新日期:2019-12-29
  • Modelling on space-domain surface waves of vertical low-Re falling film and the enhancement on mass transfer in halide-solution/air absorption
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-28
    Ronghui Qi; Chuanshuai Dong; Li-Zhi Zhang; Mingming Guo; Lin Lu

    Vertical falling film with low Reynolds number (Re) is widely used, but the influence of surface waves on mass transfer is still unclear. This paper theoretically described the wave structure along the flow direction, and evaluating the enhancement on mass transfer during halide-solution/air absorption. The effects of flow viscosity, surface tension gradient, liquid/air convective heat transfer, film thickness and flow distance are considered. Model validation were performed by comparing with the data from literatures and our experiments. For practical use, empirical correlations of wavelength and amplitude are provided, using Re, Marangoni and Nusselt numbers as variables. Wavelength increases proportionally with liquid Re, and amplitude mainly increases with the flow distance. When Re increases from 20 to 60, wave amplitude and wavelength increase by 10% and 40%. The enhancement effect is determined by the wavelength and frequency, and is more obvious under conditions of large liquid concentration or small liquid Re.

    更新日期:2019-12-29
  • Tortuosity of kerogen pore structure to gas diffusion at molecular- and nano-scales: A molecular dynamics simulation
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-28
    Jian He; Yang Ju; Laura Lammers; Karol Kulasinski; Liange Zheng

    The tortuosity of kerogen pore structures is a vital parameter in the quantification of the gas diffusion ability and production of shale reservoirs. In this study, we perform a molecular dynamics simulation on the gas diffusion in the molecular- and nano-scale pores of shale kerogen to evaluate the tortuosity of the kerogen pore structure to gas diffusion. A novel diffusion model is proposed to evaluate the tortuosity by considering gas adsorption affinity, transportation regime, and probe gas atomic size. The results indicate that the tortuosity of the kerogen pore structure to gas diffusion is not a constant; instead, it highly depends on the probe gas atomic size and gas adsorption ability. The diffusive tortuosity is overestimated when the effect of gas adsorption ability is ignored. We find that the electrical tortuosity is lower than the diffusive tortuosity. This confirms that the tortuosity is underestimated when considering a purely geometric effect.

    更新日期:2019-12-29
  • Effect of Cu modifier on the performance of CrOx/Al2O3 catalysts for isobutane dehydrogenation
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-28
    A.A. Salaeva; M.A. Salaev; G.V. Mamontov
    更新日期:2019-12-29
  • Incorporation of surface energy properties into general crystallization fouling model for heat transfer surfaces
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-28
    Amir Hossein Nikoo; Mohammad Reza Malayeri

    Crystallization fouling models for heat transfer surfaces are indispensable to provide reliable prediction of fouling behavior that would, in turn, facilitate the optimal design and operation of heat exchangers. Nonetheless, most previous models exclude surface properties in terms of surface energy and its components despite many studies confirmed otherwise. In this study, a general fouling model is developed which includes surface energy and its components. Primarily, the surface properties are incorporated into the work of adhesion. Thereafter, these properties, via a force balance, are corresponded to the shear strength of deposit in terms of removal rate. The model predicts that the shear strength of CaSO4 deposit and its adhesion on various coatings would be decreased up to 66% and 91% compared to the untreated surface, respectively. Finally, the validity of the proposed model is examined against the experimental results of CaSO4 crystallization fouling which resulted in good agreement.

    更新日期:2019-12-29
  • Wave characteristics of the falling liquid film in the development region at high Reynolds numbers
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-24
    Zongyao Wei; Yifei Wang; Ziwei Wu; Xin Peng; Guangsuo Yu

    The wave characteristics of the turbulent falling liquid film in the development region along the vertical Perspex plate were studied by using an Ultrasonic Doppler Velocimetry (a non-intrusive technique). The instantaneous thickness of the falling film at the center of the plate with axial distance ranges from 50 mm to 1300 mm was measured and the Rel (the liquid film Reynolds number) ranges from 2.28×103 to 1.43×104. The results show that the mean thickness, wave frequency and amplitude increase while the growth rate decreases with the increase of Rel. The Probability Density Function of the liquid film instantaneous thickness tends to an approximately normal distribution with increasing Rel. Furthermore, the Plateau-Rayleigh instability can cause the breakup of the liquid film surface and resist the increase of the liquid film thickness, which results in the fluctuation range of the liquid film approximate to a fixed value when the Rel>1.20×104.

    更新日期:2019-12-25
  • Universally applicable kinetic model for mixed ionic-electronic conducting membranes
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-24
    Yue Zhu; Wenping Li; Lili Cai; Xuefeng Zhu; Weishen Yang

    Kinetic model is significant for disclosing the oxygen permeation process through mixed ionic-electronic conducting (MIEC) membranes. However, current kinetic models are only applicable for certain materials. As a result, it is difficult to select a proper model to compare kinetic parameters of different membranes. In this paper, based on the dependence of oxygen vacancy concentration on oxygen partial pressure in the bulk of MIEC membrane, an extending of Zhu’s model was established for extensive MIEC membranes by revising one assumption in the original model. La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membranes with different thickness and coated/uncoated LSCF catalyst layers and La0.7Sr0.3CoO3-δ (LSC) membrane were chosen to verify the correctness of the extended model. The fitting results of LSCF and LSC are reasonable and exclusive compared to the original model and Xu-Thomson’s model. In a word, the extended model can be applied to various MIEC materials.

    更新日期:2019-12-25
  • A Temperature-dependent Potential Model for Mercury in the Description of Vapour-Liquid Equilibrium & Adsorption in Activated Carbon
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-23
    Xiu Liu; Chunyan Fan; D.D. Do; Vishnu Pareek; Peiyu Yang

    A practical potential equation for mercury was developed, by incorporating the long-ranged interaction and multi-body effects into the temperature-dependent dispersion parameters, to describe the thermodynamic properties of the liquid-vapour equilibrium and adsorption in carbonaceous materials. The collision diameter (σ) decreases and the well depth of interaction energy (ε) increases with temperature, with the product σ6ε (a measure of attraction) decreasing with temperature. The critical temperature derived from this model, 1745K, agrees well with the experimental value of 1751K, and the wetting temperature of mercury on graphite was found to be 1600K, supporting the fact that mercury does not wet carbon under ambient conditions. Furthermore, it was illustrated with mercury can fill ultrafine graphitic slit pores, whose widths less than 0.7nm, under ambient temperatures, because of the enhancement of the solid-fluid potential and the strong intermolecular interactions, and the simulation results qualitatively agree well with experimental data.

    更新日期:2019-12-23
  • Microscopic Insights into the Faradaic Reactions Effects on the Electric Double Layers
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-23
    Haiping Su; Cheng Lian; Alejandro Gallegos; Shengwei Deng; Yazhuo Shang; Honglai Liu; Jianzhong Wu
    更新日期:2019-12-23
  • EHD Effects on Periodic Bubble Formation and Coalescence in Ethanol under Non-uniform Electric Field
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-23
    Wei Zhang; Junfeng Wang; Bin Li; Hailong Liu; Christian Mulbah; Dongbao Wang; Piyaphong Yongphet

    This paper focus on the effects of electrohydrodynamic (EHD) on bubble dynamic characteristics generated on a submerged capillary in ethanol under non-uniform electric field, using high-speed photography and with a particular interest in the effect of electrical Bond number (BoE) on the bubble behaviors. The obtained results ranges of BoE from zero to 5.52 and Weber number (We) from 0.0006 to 0.1365 show that the bubble formation process associated with three stages at the low electric field strengths, including the nucleation, stable growth and necking stages, while the stable growth stage is absent for the high field strengths. With the increase of both We and BoE, the bubble period and waiting times are shortened rapidly, while the frequency is accelerated remarkably. The bubble dynamic behavior, which is characterized by the bubble volume and curvature radius, depends primarily on the BoE, and the increase in the We slightly raises the bubble volume and curvature radius at the departure time. Furthermore, it is found that with the increasing of BoE, bubbles coalescence evidenced at high We is weakened and eventually disappeared. Nevertheless, this phenomenon has the tendency to subsequently reappear at the higher We and BoE.

    更新日期:2019-12-23
  • Particle distributions in binary gas-fluidised beds: shape matters – but not much
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-23
    C.R.K. Windows-Yule; A. Moore; C. Wellard; D. Werner; D.J. Parker; J.P.K.S. Seville
    更新日期:2019-12-23
  • Continuum theory for dense gas-solid flow: A state-of-the-art review
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-21
    Junwu Wang

    Gas-solid fluidization technology has been commercialized in many industrial applications since its implementation in the fluid catalytic cracking process in the early 1940s, however, the understanding of the complex hydrodynamics of gas-solid flow inside fluidized beds is still far from satisfactory due to its dynamic and multiscale nature, especially, the critical role played by mesoscale structures. In recent decades, computational fluid dynamics (CFD) has become an important toolkit in understanding the physics of complex gas-solid flow and then for the scale-up, optimization and design of gas-solid fluidized bed reactors. This article presented a pedagogical and comprehensive review to the Navier-Stokes order continuum theory for CFD simulation of the hydrodynamics of gas-solid fluidization, without taking the effects of heat and mass transfer as well as chemical reactions into consideration. A concise introduction to the methods for multiscale CFD simulation of gas-solid fluidization was firstly provided, which include direct numerical simulation, (coarse-grained) discrete particle method, kinetic method, continuum method and mesoscale-structure-based multiscale method. The underlying postulates of homogeneous continuum theory that assume the structure inside each computational cell is (nearly) homogeneous were then examined, followed by an overview of the constitutive relationships available in literature, including the particle phase stress models, the interphase drag models and the models for particle-wall interactions. The importance of mesoscale structures that take the form of gas bubbles and/or particle clusters and streamers in the quantification of the hydrodynamics of gas-solid flows was then addressed, and the explicit resolution (or highly resolved) method and implicit modeling method for quantifying the effects of mesoscale structures in continuum modeling of gas-solid fluidization were highlighted. Coarse grid simulation of large scale fluidized beds with proper mesoscale, sub-grid scale or turbulent models for constitutive relationships were then reviewed, focusing on the filtered method, turbulence modelling and heterogeneity-based method where the energy-minimization multi-scale (EMMS) based method is a representative. Finally, the scope for the further research areas is described.

    更新日期:2019-12-21
  • Laminated superwetting aerogel/membrane composite with large pore sizes for efficient separation of surfactant-stabilized water-in-oil emulsions
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-20
    Xuejie Yue; Woyuan Li; Zhangdi Li; Fengxian Qiu; Jianming Pan; Tao Zhang

    Although superwetting filtration membranes have been widely used, they suffer from the disadvantages of lower flux and membrane fouling caused by the nanoscale pore size. Herein, a laminated cellulose aerogel/membrane composite with large pore size is fabricated via combining facile freeze-drying and hydrophobic modification using cellulose fibers as building blocks. An ultrathin silanization coating layer on cellulose fibers surface is constructed via directly coupling alkoxysilane and endows the composite with excellent superhydrophobicity (161o) and superoleophilicity (0o). Upon contact with a water-in-oil emulsion, the aerogel layer causes the micrometer-sized water droplets to coalesce. The coalesced water droplets are then repelled by the membrane layer with large pore size, achieving ultrafast gravity-driven separation with high separation efficiency (99.5%) and separation flux (12890 L m−2 h−1). Moreover, the composite exhibits ease to cycle and good usability. The outstanding performance of composite highlights its potential applications in the field of oil related industry.

    更新日期:2019-12-20
  • Mass transport in a partially filled horizontal drum: Modelling and experiments
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-19
    Érika Fernanda Rezendes Tada; Andreas Bück; Evangelos Tsotsas; João Cláudio Thoméo
    更新日期:2019-12-20
  • A Multiple-outlet Adaptive Boundary Condition for Eulerian- Eulerian Multiphase Numerical Simulation
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-19
    Dongdong Fan; Wei Tan; Guorui Zhu

    An adaptive algorithm was developed to handle some multiphase situations where outlet information is included in results or multiple inlets/outlets are implemented while only flow rates through inlets/outlets are known. This algorithm includes a first-order expanded Bernoulli equation and a mixed approximation algorithm. The expanded Bernoulli equation offers an initialization value for a concerned object for subsequent approximation processes. The mixed approximation algorithm completes final convergence via iteration and correction. The executed code was successfully compiled into a commercial computational fluid dynamics software. To test the algorithm, a series of corresponding experiments were performed. Three key parameters including the validity of the initialization condition from the expanded equation, convergence efficiency and reliability were evaluated and discussed. The results show that this boundary condition could accomplish the desired functions and maintain errors lower than 15% compared to experimental data, and in less rigorous applications, the error may be approximate to 5%.

    更新日期:2019-12-20
  • Large–eddy simulation in a Sonolator high–pressure homogeniser
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-19
    Ioannis Bagkeris; Vipin Michael; Robert Prosser; Adam Kowalski

    This paper examines the fluid dynamics of a pilot–scale high–pressure homogeniser using large–eddy simulation. The mixer consists of a non–planar elliptic jet released into a confined cylindrical chamber. The simulated results are validated by comparing mean quantities with published experimental data. The evolution of the shear layers in the jet near–field shows a localised region of high turbulent energy dissipation rate in the major plane, whereas in the minor plane the dissipation rate is of smaller magnitude and spreads over a wider region. The validity of the turbulence isotropy assumption, typically made in dispersed–phase modelling, is examined. Energy spectra exhibit an amplification close to the nozzle at frequencies associated with vortex shedding. Kolmogorovs classical 2/3 scaling in the second–order structure functions is found to be overshadowed by vortex shedding, resulting in steeper slopes in the jet near–field, where the rate of energy dissipation assumes the largest value in the mixer.

    更新日期:2019-12-20
  • 更新日期:2019-12-19
  • A Computational Tool for Parameter Estimation in EoS: New Methodologies and Natural Gas Phase Equilibria Calculations
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-19
    Samir S. Abunahman; Letícia C. dos Santos; Frederico W. Tavares; Georgios M. Kontogeorgis

    Brazilian pre-salt reservoirs represent the discovery of large amounts of light oil, but at high pressures and containing high concentration of CO2. Proper parameter estimation procedures are essential to perform more accurate predictions of their thermodynamic properties. Therefore, two new methodologies for such calculations have been implemented here: by applying simultaneously VLE and LLE to the metric; and by handling water content in dew point conditions. Utilizing the Cubic-Plus-Association (CPA) EoS, they were employed to obtain new parameters for water. Also, new parameters were obtained for H2O + CO2 mixtures, whose average absolute deviation in water content at high pressures fell from 24% to 3% compared to previous publications. The same procedure was performed for other aqueous mixtures containing H2S and light hydrocarbons. Finally, this study has been applied into a natural gas compressing simulation with CO2, studying streams properties comparing the parameters obtained in this work with the literature.

    更新日期:2019-12-19
  • Assessment of turbulence models for bubbly flows: toward a Five-Equation turbulence model
    Chem. Eng. Sci. (IF 3.372) Pub Date : 2019-12-18
    Ghazi Bellakhal Ghazi Bellakhal; Fathia Chaibina; Jamel Chahed

    The paper presents an assessment of turbulence models in dispersed bubbly flows based on an analysis of their application to uniform and uniformly sheared homogeneous turbulence. This analysis leads to the development of a five-equation model where the total turbulent fluctuations in bubbly flow is submitted to a double decomposition: First, the turbulent fluctuations are split into Shear-Induced-Turbulence (SIT) and Bubble-Induced-Turbulence (BIT) components. Secondly, The BIT contribution is split into two components corresponding to non-dissipative pseudo-turbulent part and dissipative turbulent part produced by local shear in bubble’s wake. Consequently, the total turbulent energy is split into three contributions : two dissipative quantities kt and ks produced respectively by gradient of mean velocity in the liquid phase and by local shear in bubble’s wake both are described by their modeled transport equations as well as their dissipation rates εt and εs; and a non-dissipative component kp attributed to fluctuations of potential flow around bubbles described by its modeled transport equation. This model was implemented in CFD code and validated in homogeneous bubbly turbulence situations. The numerical results show a satisfactory agreement with experimental data of turbulence.

    更新日期:2019-12-19
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