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Showing records 36670 to 36694 of 43292. [First] Page: 1 1464 1465 1466 1467 1468 1469 1470 1471 1472 Last
Non-Thermal Technologies Combined with Antimicrobial Peptides as Methods for Microbial Inactivation: A Review
Larissa Andaluz-Mejía, Daniela Ruiz-De Anda, César Ozuna
February 21, 2023 (v1)
Subject: Biosystems
Keywords: bacteriocin, chemical preservatives, high hydrostatic pressure, nisin, pulsed electric fields, ultrasound
Non-thermal technologies allow for the nutritional and sensory properties of foods to be preserved, something that consumers demand. Combining their use with antimicrobial peptides (AMPs) provides potential methods for food preservation that could have advantages over the use of chemical preservatives and thermal technologies. The aim of this review was to discuss the advances in the application of non-thermal technologies in combination with AMPs as a method for microbial inactivation. Published papers reporting studies on the combined use of power ultrasound (US), pulsed electrical fields (PEF), and high hydrostatic pressure (HHP) with AMPs were reviewed. All three technologies show a possibility of being combined with AMPs, generally demonstrating higher efficiency than the application of US, PEF, HHP, and AMPs separately. The most studied AMP used in combination with the three technologies was nisin, probably due to the fact that it is already officially regulated. However, the com... [more]
Particle Residence Time Distribution in a Concurrent Multiphase Flow Reactor: Experiments and Euler-Lagrange Simulations
Laura Unger, Juan Sebastián Gómez Bonilla, Dyrney Araújo dos Santos, Andreas Bück
February 21, 2023 (v1)
Keywords: axial flow structure, downer reactor, gas-particle flow, residence time distribution, thermal rounding
The present work focuses on investigating the residence time behavior of microparticles in a concurrent downer reactor through experiments and numerical simulations. For the numerical simulations, a three-dimensional multiphase model was developed using the Euler-Lagrange approach. The experiments were performed in a 0.8 m-long steel reactor with gravitational particle injection. The effects of different operating conditions, e.g., the sheath gas velocity on the particle residence time distribution were assessed. An increase in the sheath gas flow rate led to a decrease in the peak residence time, although the maximum residence time increased. Regarding the lowest sheath gas flow rate, the particles’ peak residence time was twice as high compared to the peak residence time within the highest flow rate. The particles’ residence time curves presented a broad distribution coinciding with the size distribution of the powder. The numerical results agreed with the experimental data; thus, th... [more]
Evaluation of Centrifugal Force, Erosion, Strain Rate, and Wall Shear in a Stairmand Cyclone
Sajed Naiemi Dizajyekan, Gholamhossein Shahgholi, Adel Rezvanivand Fanaei, Vahid Rostampour, Vali Rasooli Sharabiani, Mariusz Szymanek, Ryszard Kulig
February 21, 2023 (v1)
Keywords: centrifugal force, cyclone separator, Euler number, pressure drop, wheat conveying
In the present study, imperative parameters including centrifugal force, erosion, streamline, strain rate, and wall shear are evaluated in a cyclone separator. The flaw of the cyclone surface due to erosion is an acute problem in the industry. According to the great importance of the centrifugal force on the separation phenomenon, a comprehensive study is conducted. A computational fluid dynamics (CFD) simulation is realized by applying a Reynolds stress turbulence model (RSM), and particle−air interactions were modeled using a discrete phase model (DPM). The result shows a good agreement between the experimental data and CFD simulation on the tangential velocity and pressure drop. The maximum deviation of the validation process is 6.8%. It is found that the centrifugal force within the cyclone is increased with an enhancement in the inlet velocity. The separation efficiency indicates an increase−decrease treatment in various inlet velocities with inlet velocity up to 16 m⋅s−1 but decr... [more]
Natural Frequency Analysis of Horizontal Piping System Conveying Low Viscosity Oil−Gas−Water Slug Flow
Liedong Mi, Yunlong Zhou
February 21, 2023 (v1)
Keywords: critical gas velocity, natural frequency, slug flow, water cut
The water cut (WC) has a significant effect on the flow parameters, such as liquid holdup, liquid phase velocity, and flow regimes of the low-viscosity oil−gas−water slug flow, and it can change the vibration characteristics of piping systems. To study the effect of water cut on the vibration characteristics of piping systems conveying such internal flow, a new dynamic model is developed. Galerkin’s method is used to discretize the equation and determine the natural frequencies by solving for the eigenvalues of the equation coefficient matrix. The results show that in the range of 10−90% WC, the natural frequency increases and then decreases, and the turning point occurs near the phase inversion region (WC = 40−60%). The main reason is the highly effective viscosity in the phase inversion region, which leads to an increase in the liquid holdup. The natural frequency increases and then decreases with superficial gas velocity, and the inflection point decreases with the increase in water... [more]
Electric Drives: Complexes of Nonlinear Electromechanical Links Identified by Nonlinear Transfer Functions and Families of Frequency Characteristics
Vladimir L. Kodkin, Alexander A. Baldenkov, Maksim A. Grigoriev
February 21, 2023 (v1)
Keywords: electric drive, hyperstability, nonlinear systems
The article considers a generalized block diagram of electromechanical systems: electric drives. It is shown that all their elements have significant nonlinearities that cannot be neglected when designing systems with maximum accuracy and speed. A method for taking into account the influence of nonlinearities on the electric drive characteristics, the method of nonlinear transfer functions and families of frequency characteristics, is proposed. It is shown how these nonlinear transfer functions make it possible to form correction and control systems for electric drives in the modes of processing task signals and in the modes of parrying the load.
Real-Time Optimization of Wastewater Treatment Plants via Constraint Adaptation
Ahteshamul Haq, Babji Srinivasan, Dominique Bonvin
February 21, 2023 (v1)
Subject: Optimization
Keywords: BSM1, constraint adaptation, fast constraint adaptation, real-time optimization, WWTP
An important requirement of wastewater treatment plants (WWTPs) is compliance with the local regulations on effluent discharge, which are going to become more stringent in the future. The operation of WWTPs exhibits a trade-off between operational cost and effluent quality, which provides a scope for optimization. Process optimization is usually done by optimizing a model of the process. However, due to inevitable plant−model mismatch, the computed optimal solution is usually not optimal for the plant. This study represents the first attempt to handle plant−model mismatch via constraint adaptation (CA) for the real-time optimization of WWTPs. In this simulation study, the “plant” is a model adopted from the BSM1 benchmark, while a reduced-order “model” is used for making predictions and computing the optimal inputs. A first implementation uses steady-state measurements of the plant constraints to adjust the model in the optimization framework. A fast CA technique is also proposed, whic... [more]
Stochastic Stabilization for Discrete-Time System with Input Delay and Multiplicative Noise in Control Variable
Cheng Tan, Jianying Di, Mingyue Xiang, Ziran Chen, Binlian Zhu
February 21, 2023 (v1)
Keywords: critical stabilization, essential destabilization, input delay, spectrum technique, stochastic system
The stabilization problems for time-delay stochastic systems with multiplicative noise in the control variable are investigated in this paper. The innovative contributions are described as follows. Since the past work on stabilization is based on some delay-dependent algebraic Riccati equation (DARE), how to numerically calculate the stabilizing solution remains an unsolved and open problem. On the one hand, an iterative algorithm for computing the unique stabilizing solution of DARE is proposed, while the convergence property is also proved. On the other hand, the concepts of critical stabilization and essential destabilization are proposed as a supplement to stochastic stabilization in terms of spectrum technique. Moreover, the Lyapunov-based necessary and sufficient conditions are developed.
Exploring Key Decisive Factors in Manufacturing Strategies in the Adoption of Industry 4.0 by Using the Fuzzy DEMATEL Method
Fawaz M. Abdullah, Abdulrahman M. Al-Ahmari, Saqib Anwar
February 21, 2023 (v1)
Subject: Environment
Keywords: competitive capabilities, fuzzy DEMATEL method, industry 4.0 technologies, manufacturing strategies, smart manufacturing
Globalization has created a highly competitive and diverse market, an uncertain and risky business environment, and changing customer expectations. An effective manufacturing strategy reduces complexity and provides organizations with a well-organized manufacturing structure. However, existing research on manufacturing strategies appears scattered, lacking systematic understanding and finding no causal relationship between manufacturing strategies’ outputs (MSOs) and their importance. Therefore, this study is a pioneer in identifying the influential factors of MSOs in the adoption of Industry 4.0 (I4.0) technologies utilizing the decision-making trial and evaluation laboratory (DEMATEL) approach. This method is considered an effective method for identifying the cause-effect relationship of complex problems. It evaluates interdependent relationships among MSO factors from the perspective of academic and industry experts. Identifying cause and effect factors leads to increasing the marke... [more]
Exploring the Role of Initial Droplet Position in Coalescence-Induced Droplet Jumping: Lattice Boltzmann Simulations
Yuhao Zhu, Xiao Yan, Lei Ma, Zhichun Liu, Wei Liu
February 21, 2023 (v1)
Keywords: droplet jumping, Lattice Boltzmann method, superhydrophobic surface
Coalescence-induced droplet jumping on superhydrophobic surfaces with different initial positions was numerically simulated using the 2D multi-relaxation-time (MRT) Lattice Boltzmann method (LBM). Simulation results show that for coalesced droplets with radii close to the structure length scale, the change of initial droplet positions leads to a significant deviation of jumping velocity and direction. By finely tuning the initial droplet positions on a flat-pillared surface, perpendicular jumping, oblique jumping, and non-jumping are successively observed on the same structured surface. Droplet morphologies and vector diagrams at different moments are considered. It is revealed that the asymmetric droplet detachment from the structured surface leads to the directional transport of liquid mass in the droplet and further results in the oblique jumping of the coalesced droplet. In order to eliminate the influence of initial droplet position on droplet jumping probability, a surface with p... [more]
Flow Modeling in a Vortex Chamber of a Liquid−Steam Jet Apparatus
Iurii Merzliakov, Ivan Pavlenko, Marek Ochowiak, Vitalii Ivanov, Praveen Agarwal
February 21, 2023 (v1)
Keywords: Energy Efficiency, flow deflection angle, modified Euler number, oblique cut, process innovation, underheated liquid, vortex flow
The article investigated the flow of boiling streams through a nozzle with an oblique cut. Due to this flow organization, deviation from the nozzle axis at the vortex chamber inlet occurred. The study of flow modeling in the inlet section was carried out. The flow design and the calculation scheme of the vortex liquid−steam jet apparatus were proposed. Analytical expressions between the main operating parameters were obtained according to the developed mathematical model. A recommended oblique-cut angle for the active-flow nozzle was evaluated considering the transition through the first critical section based on the tangential velocity flow model. Validation of the mathematical model in the inlet section of the vortex chamber was provided based on the comparison with available experimental data. Flow visualization in the inlet section of the vortex chamber was obtained. The assumption of uneven flow distribution was confirmed experimentally. Overall, the boiling liquid flow was implem... [more]
Processing of Carob Kernels to Syrup by Ultrasound-Assisted Extraction
Maria Lisa Clodoveo, Pasquale Crupi, Marilena Muraglia, Filomena Corbo
February 21, 2023 (v1)
Subject: Biosystems
Keywords: Amele cv., carob pods, flavonols, green extraction, tannins
Carob syrup is one of the most important carob products, which can have applications in pastry and confectionery, as a fruit preservative, but also in the pharmaceutical field because of the antimicrobial activity due to its polyphenol content. Carob syrup is traditionally made through a very time-consuming process, involving solid−liquid extraction in boiling water and concentration at a high temperature (>100 °C), which potentially causes the degradation of the active compounds (i.e., procyanidins or flavonol glycosides). Therefore, in this work, an alternative and less drastic method based on ultrasound technology was proposed to produce carob syrup. Processing conditions (i.e., time, temperature, and liquid−solid ratio) influencing the extraction of total soluble solids (TSS) and total phenolic compounds (TPC) were optimized using a central composite design coupled to response surface methodology. Reliable mathematical models allowed us to predict the highest TSS (24 ± 2 °Brix) and... [more]
Development of Evaluation Methods for Anti-Glycation Activity and Functional Ingredients Contained in Coriander and Fennel Seeds
Akiyoshi Sawabe, Atsuyuki Yamashita, Mei Fujimatsu, Ryuji Takeda
February 21, 2023 (v1)
Keywords: AGEs (advance glycation end-products), anti-aging, coriander, evaluation method for anti-glycation activity, fennel, spice seed
Spices are known to have various physiological functions. We focused on the anti-glycation effects of spices, researched anti-glycation active ingredients in coriander (Coriandrum sativum L.) and fennel (Foeniculum vulgare) seeds, and conducted experiments using human skin-derived fibroblast TIG-110 cells as a model of glycation. We isolated 11 compounds from two spice seeds and found several substances that showed anti-glycation activity. A new compound (5,5′-diallyl-2,2′-diglucopyranosyl-3,3′-dimethoxy diphenyl ether) was isolated from fennel seeds and showed high anti-glycation activity with an IC50 value of 0.08 mM, thereby indicating a high anti-glycosylation activity. In this study, we established a glyoxal (GO)-induced glycation test method for human skin cells, confirmed the anti-glycation effect of spice seeds using this glycation induction model, and found that the exposure of TIG-110 human skin-derived fibroblast cells to GO reduced cell viability. The most stable conditions... [more]
Analysis of Grid Response Strategies for the Safety Behavior Risk Events of Transportation System Based on System Dynamics—“the Assistant Watchman Does Not Appear as Required”
Huafeng Zhang, Changmao Qi, Mingyuan Ma
February 21, 2023 (v1)
Keywords: grid theory, hazard factors, railway transportation system, risk response, system dynamics
Employees are the most important and dynamic elements in the railway transportation system. How to achieve accurate control of inertial violation of “key person, key matter, key period”, and formulate more personalized risk response strategy is a thorny problem that faced by safety managers. The existing risk response usually takes control measures from the perspective of the system as a whole, ignoring the heterogeneity of risk, and the selection of response strategies only considers the target risks to be dealt with, ignoring the secondary risks that may occur in the process of risk response, or the residual risks formed by changing the existing risk, coupled with the lack of quantitative evaluation of risk response effect, resulting in poor risk response effect. By introducing the grid theory and taking the risk event of “the assistant watchman does not appear as required” at Huangyangcheng station of Shenshuo Railway as an example, this study constructs a grid response model of the... [more]
Special Issue on “Soil and Sustainable Development: Challenges and Solutions”
David Fernández-Calviño, Manuel Arias-Estévez, Ruth Pereira, Joana Lourenço
February 21, 2023 (v1)
Subject: Environment
Food production is increasing year by year, with modern agriculture occupying high-fertility soils [...]
Effect of Bacillus Additives on Fermentation Quality and Bacterial Community during the Ensiling Process of Whole-Plant Corn Silage
Xiaojun Guo, Wei Guo, Ming Yang, Yuelong Sun, Yujing Wang, Yan Yan, Baocheng Zhu
February 21, 2023 (v1)
Keywords: Bacillus additive, bacterial community, deoxynivalenol, ensiling process, lignocellulose, whole-plant corn silage
The aim of this study was to evaluate the effects of a complex Bacillus subtilis additive on the fermentation quality and bacterial community during the ensiling process of whole-plant corn silage (WPCS). The pH values of WPCS treated with the B. subtilis inoculant decreased faster than those of the control without inoculant, and significantly higher contents of lactic acid (LA) and acetic acid (AA) were observed. After 45 days of ensiling, the LA contents reached 7.95% (w/w). In the treatment group, the neutral detergent fibre (NDF) and acid detergent fibre (ADF) contents decreased significantly compared to the control, and the degradation rates of the NDF and ADF were 26.52% and 27.34% after 45 days, respectively. The deoxynivalenol (DON) content in the treatment group decreased to 205.67 μg/kg, which was significantly lower than the content of 382.51 μg/kg in the control group. The results indicated the positive effect of the B. subtilis inoculant in improving WPCS fermentation, esp... [more]
Tech-Economic Assessment of Power Transmission Options for Large-Scale Offshore Wind Farms in China
Qin Jiang, Baohong Li, Tianqi Liu
February 21, 2023 (v1)
Keywords: China, economic evaluation, HVDC, offshore wind, opex
China is taking initiative in energy transition to cope with the long-term controversy of its enormous energy consumption, aiming to use less carbon. Wind power, especially offshore wind energy, has become a prevailing alternative due to its low carbon emissions, renewability, competitiveness, and operation security. The layout of a transmission channel is a key consideration in marine project implementation. This paper investigates the technical characteristics, application status, and viable advantages of a conventional AC transmission, voltage source converter-based high-voltage direct current (VSC-HVDC) transmission, gas-insulated line (GIL) transmission, and hybrid HVDC transmission. A component-resolved evaluation model was proposed to estimate the costs to be incurred of four electrical transmission options for offshore wind power along the coast of Eastern China, with technical feasibility and economical considerations. Cost comparisons and component sensitivity analyses were d... [more]
Study of the Impact of Tube Configurations on the Local Heat Transfer Coefficient in Mimicked Fischer-Tropsch Bubble Column Reactor
Abdulrazaq Nadhim Alzamily, Abbas J. Sultan, Amer A. Abdulrahman, Hasan Sh. Majdi
February 21, 2023 (v1)
Keywords: bubble column, bundle of heat exchanging tubes, Fischer-Tropsch process, heat transfer coefficient, sophisticated heat transfer technique, tube configurations
An experimental investigation was conducted to examine, for the first time, the influences of using different designs of tube arrangements on the local heat transfer coefficient (LHTC) in a bubble column (with a diameter of 0.13 m) equipped densely with a bundle of tubes. The effect of using two different designs of tube arrangements has been examined for a broad range of gas flow rates using a sophisticated heat transfer technique. The obtained results indicate that the LHTC increases significantly with increasing the gas velocity, regardless of the design and installation of the tubes in the column. Additionally, the shape of the LHTC’s profiles alters considerably by the presence of a bundle of tubes and their arrangements. Moreover, the results indicate that the square tube pitch arrangement provides uniform heat transfer profiles, which enhance the performance of the bubble column reactor by 30%. Furthermore, the heat transfer profiles were found to be varied with the axial height... [more]
Thermal Operation Maps for Lamm−Honigmann Thermo-Chemical Energy Storage—A Quasi-Stationary Model for Process Analysis
Elisabeth Thiele, Felix Ziegler
February 21, 2023 (v1)
Keywords: absorption storage, Carnot battery, control strategy, storage and conversion, storage capacity, storage efficiency, thermal operation map, thermochemical energy storage
The Lamm−Honigmann energy storage is a sorption-based storage that can be arbitrarily charged and discharged with both heat and electrical power. The mechanical charging and discharging processes of this storage are characterized by an internal heat transfer between the main components, absorber/desorber and evaporator/condenser, that is driven by the working-fluid mass transferred between those components with the help of an expansion or compression device, respectively. In this paper, thermal operation maps for the mechanical charging and discharging processes are developed from energy balances in order to predict power output and storage efficiency depending on the system state, which, in particular, is defined by the mass flow rate of vapor and the salt mass fraction of the absorbent. The conducted method is applied for the working-fluid pair LiBr/H2O. In a first step, a thermal efficiency is defined to account for second-order losses due to the internal heat transfer; e.g., for di... [more]
Thermogravimetric Study on Peat Catalytic Pyrolysis for Potential Hydrocarbon Generation
Mohammed A. Khelkhal, Semen E. Lapuk, Aleksey V. Buzyurov, Tatiana O. Krapivnitskaya, Nikolay Yu. Peskov, Andrey N. Denisenko, Alexey V. Vakhin
February 21, 2023 (v1)
Subject: Materials
Keywords: activation energy, Catalysis, enthalpy, entropy, Friedman, Gibbs free energy, KAS, peat, TG, transition metals
Peat has attracted considerable interest as a potential source of alternative fuel in terms of improving hydrocarbons production and satisfying market demand. The next decade is likely to witness a raise in its exploitation. Nevertheless, the characteristics of peat pyrolysis process, via which many experts expect a considerable generation of hydrocarbons, have not been dealt with in depth. In the present study we have applied thermal analysis combined with isoconversional and model methods for clarifying the kinetic and thermodynamic aspects of the process of generating hydrocarbons from peat via pyrolysis in the absence and presence of iron tallates as a catalytic agent. The obtained results showed a positive effect of the opted catalyst on the process of peat pyrolysis. It has been shown that the catalyst is able to reduce the energy of activation of peat pyrolysis process. Moreover, the Gibbs energy, enthalpy and entropy of complex formation values have been found lower in the pres... [more]
Estimation Parameters of Soil Solute Transport Processes by Using the Electric Resistivity Method
Debao Lu, Yinfeng Xia, Nan Geng, Hui Wang, Jinlin Qian, Cundong Xu
February 21, 2023 (v1)
Subject: Environment
Keywords: breakthrough curves, ERT, MIM, preferential solute transport
Preferential solute transport is a common phenomenon in soil, and it is of great significance to accurately describe the mechanism of pollutant transport and water and soil environmental governance. However, the description of preferential solutes still relies on applying solute breakthrough curves for model parameters fitting. At present, most of the solute breakthrough curves are obtained indoors, and with some limitations. Therefore, this study established a method for securing solute breakthrough curves based on the electrical resistivity method. The research results show that the change in soil concentration during the tracer infiltration process can be captured by establishing the fitting relationship between soil resistivity and solute concentration. Then the solute breakthrough curve can be found. Through a time moment analysis, the difference between the breakthrough curve parameters obtained by the traditional method and the resistivity method is slight; the average error is... [more]
Research on Mixing Behavior in a Combined Top−Bottom−Side Blown Iron Bath Gasifier
Mingfei Sun, Hongbin Zhang, Jieyu Zhang, Bo Wang
February 21, 2023 (v1)
Keywords: iron bath, mixing time, numerical simulation, physical model
The iron bath gasifier studied in this paper is a new type of reactor for handling organic solid waste, in which the complex transport phenomena comprising high temperature, the multiphase flow, mixing, and chemical reaction takes place. It is of great significance to study the melt’s flow and mass transfer behavior in this reactor. The influence of different process parameters on the mixing behavior of the molten pool was studied by the water modeling experiment and numerical simulation method. The experimental results show that the height of the water phase has a highly significant effect on the mixing time of the molten pool, followed by the horizontal angle of the side gun and the bottom blowing flow rate. As the height of the water increases, the mixing time decreases. When the horizontal angle of side lances increases, the mixing time decreases. With the increase in the flow rate of the bottom lance, the mixing time decreases. The results obtained by numerical simulation were com... [more]
Influence of Chromatographic Conditions on LOD and LOQ of Fluoxetine and Sertraline Analyzed by TLC-Densitometric Method
Wioletta Parys, Alina Pyka-Pająk
February 21, 2023 (v1)
Subject: Materials
Keywords: fluoxetine, limit of detection (LOD), limit of quantification (LOQ), NPTLC, RPTLC, sertraline
This research introduces the analysis of fluoxetine and sertraline by means of the TLC-densitometric method. They provide information on LOD and LOQ under various chromatographic conditions. The study used adsorption (NPTLC) and partition (RPTLC) thin-layer chromatography in combination with a densitometric analysis. Four types of chromatographic plates precoated with: silica gel 60 F254, silica gel 60, silanized silica gel 60 F254 (RP-2), and a mixture of silica gel 60 and kieselguhr F254, as well as three mobile phases: chloroform + methanol + ammonia (9:1:0.4, v/v/v), chloroform + methanol + glacial acetic acid (5:4:1, v/v/v), and acetone + toluene + ammonia (10:9:1, v/v/v), were used in NPTLC. RP-18F254 and silanized silica gel 60 F254 (RP-2) plates and four mobile phases: methanol + water (10:0 and 9:1, v/v), acetone + water (10:0 and 9:1, v/v), were used in RPTLC. The lowest LOD and LOQ values for fluoxetine were obtained using a silanized silica gel 60 F254 (RP-2) with acetone +... [more]
Edible Insects’ Transformation for Feed and Food Uses: An Overview of Current Insights and Future Developments in the Field
Rachelle El Hajj, Houcine Mhemdi, Colette Besombes, Karim Allaf, Victor Lefrançois, Eugène Vorobiev
February 21, 2023 (v1)
Subject: Biosystems
Keywords: biomolecules, chitin, chitosan, edible insects, Extraction, lipids, proteins
The integration of insect-derived extracts in feed and food products has become a field of growing interest in recent years. In this review, we collect different studies carried out on edible insects’ transformation processes and focus on the various treatment operations, extraction technologies, and solvents used in different processing steps. We include an overview of current insights into the different steps of the transformation process: insect reception, killing methods, pretreatments, storage, delipidation, protein extraction, as well as chitin and chitosan extraction. Finally, we reflect on the most important future challenges of this sector.
Improved Constrained Predictive Functional Control Using Extended Non-Minimal State Space Formulation for the Cement Production Process
Qiuwen Luo, Jianjun Bai, Feng Wu
February 21, 2023 (v1)
Keywords: constraint dealing method, denitration process, extended state space model, predictive functional control, relaxation factors
In this article, an improved constraint dealing method and an extended state space model-based constrained predictive functional control (PFC) approach is developed for the denitration process in cement production. To improve the control effect of the presented strategy, first, an enhanced form-based state space model in which the changes of the output predictions can be regulated to achieve smoother system dynamics is constructed. Then, a modified constraint dealing scheme, which integrates the relaxation factors to improve the success probability of solving the relevant optimization, is also introduced for the proposed method. On the basis of the two merits, better ensemble control performance is anticipated. Simulations on the regulation of the NOx concentration in the denitration process prove the validity of the proposed constrained PFC strategy.
Predicting Mass Transfer in Liquid−Liquid Extraction Columns
Alex Fells, Andrea De Santis, Marco Colombo, Daniel W. Theobald, Michael Fairweather, Frans Muller, Bruce Hanson
February 21, 2023 (v1)
Keywords: Computational Fluid Dynamics, droplet population balance, liquid–liquid extraction, mass transfer, multiphase flows, pulsed column, pulsed sieve-plate extraction column, rotating disc column, solvent extraction
In this work, the GEneralised Multifluid Modelling Approach (GEMMA) is applied to the simulation of liquid−liquid extraction in a Rotating Disc Column (RDC) and a Pulsed Sieve-plate Extraction Column (PSEC). A mass transfer modelling methodology is developed, in which the multiphase flows, droplet size distribution and dispersed phase holdup predicted with computational fluid dynamics are coupled to mass transfer correlations to predict the overall mass transfer. The numerical results for the stage-averaged dispersed phase holdup, Sauter mean droplet diameter and axial solute concentration in the RDC and PSEC agree with experimental observations. The proposed modelling method provides an accurate predictive tool for complex multiphase flows, such as those observed in intensified liquid−liquid extraction, and provides an alternative approach to column design using empirical correlations or pilot plant study.
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