Records with Subject: Modelling and Simulations
Showing records 1 to 25 of 5392. [First] Page: 1 2 3 4 5 Last
Study on the Influence of the Joint Angle between Blast Holes on Explosion Crack Propagation and Stress Variation
Xiangyang Wang, Xiantang Zhang, Jingshuang Zhang, Hongmin Zhou, Peng Zhang, Dan Li
February 19, 2024 (v1)
Keywords: crack propagation, effective stress, joint angle, numerical simulation, stress wave
The joints and fissures in a natural rock mass can affect the mechanical properties of the rock mass, the propagation of a blasting stress wave, and the blasting effect of the smooth surface of roadways. In the process of roadway drilling and blasting, there will inevitably be some joints between the two blast holes. Taking the joint angle as the starting point, this paper studies the rule of rock explosion crack propagation and stress variation when there are joints with different angles between two blast holes and analyzes the influence of joints on rock mechanical properties and blasting effects. The numerical simulation method and the software ANSYS/LS-DYNA are used to establish 7 rock mass models with various joint angles. When there is no joint between two holes and joints of 15°, 30°, 45°, 60°, 75°, and 90°, the propagation of explosive cracks and stress variations in the rock mass are discussed. The results show that the joints at different angles have obvious guiding and block... [more]
Computational Fluid Dynamics Simulation of Combustion and Selective Non-Catalytic Reduction in a 750 t/d Waste Incinerator
Hai Cao, Yan Jin, Xiangnan Song, Ziming Wang, Baoxuan Liu, Yuxin Wu
February 10, 2024 (v1)
Keywords: gas-solid two-phase combustion coupling, grate furnace, numerical simulation, SNCR
In this study, a Computational Fluid Dynamics (CFD) approach using Ansys Fluent 15.0 and FLIC software was employed to simulate the combustion process of a 750 t/d grate-type waste incinerator. The objective was to assess the performance of Selective Non-Catalytic Reduction (SNCR) technology in reducing nitrogen oxide (NOx) emissions. Two-stage simulations were conducted, predicting waste combustion on the bed and volatile matter combustion in the furnace. The results effectively depicted the temperature and gas concentration distributions on the bed surface, along with the temperature, velocity, and composition distributions in the furnace. Comparison with field data validated the numerical model. The findings serve as a reference for optimizing large-scale incinerator operation and parameter design through CFD simulation.
Research Regarding the Dimensional Precision of Electrical Steel Strips Machined by Waterjet Cutting in Multilayer Packages
Daniel Nasulea, Alexandru Catalin Filip, Silvia Zisu, Gheorghe Oancea
February 10, 2024 (v1)
Keywords: dimensional accuracy, electrical motor, electrical steel strip, multilayer package, waterjet machining
Manufacturing parts made of thin steel in small batches is a challenging task in terms of reaching the proper balance between the productivity, the cost, and the dimensional precision. This paper presents the results of experimental research about manufacturing electrical steel thin parts using abrasive waterjet cutting. For a certain increase of productivity and a more efficient process, the parts were cut using multilayer packages of steel strips. The main objective was to analyze the influence of the number of layers on the dimensional precision of parts. Preliminary tests were performed, followed by a full factorial experiment using two independent parameters, the number of layers and the traverse speed. The parts were measured on a noncontact vision measurement machine and mathematical models were determined to predict the parts deviations depending on the independent parameters used. A practical validation of the models was performed. The main conclusion is that the number of lay... [more]
Mathematical Modeling of Prediction of Horizontal Wells with Gravel Pack Combined with ICD in Bottom-Water Reservoirs
Shili Qin, Ning Zhang, Bobo Cao, Yongsheng An, Runshi Huo
February 10, 2024 (v1)
Keywords: bottom-water reservoir, gravel pack, horizontal wells, inflow control device
During the development of horizontal wells in bottom-water reservoirs, the strong heterogeneity of reservoir permeability leads to premature bottom-water breakthroughs at locations with high permeability in the horizontal wellbore, and the water content rises rapidly, which seriously affects production. To cope with this problem, a new technology has emerged in recent years that utilizes gravel filling to block the flow in the annulus between the horizontal well and the borehole and utilizes the Inflow Control Device (ICD) completion tool to carry out segmental water control in horizontal wells. Unlike conventional horizontal well ICD completions that use packers for segmentation, gravel packs combined with ICD completions break the original segmentation routine and increase the complexity of the production dynamic simulation. In this paper, the flow in different spatial dimensions, such as reservoirs, gravel-packed layers, ICD completion sections, and horizontal wellbores, is modeled... [more]
Adsorption of Multi-Collector on Long-Flame Coal Surface via Density Functional Theory Calculation and Molecular Dynamics Simulation
Gan Cheng, Yujie Peng, Yang Lu, Mengni Zhang
February 10, 2024 (v1)
Keywords: Adsorption, collector, long-flame coal, molecular dynamics, quantum chemistry
The quantum chemical properties of long-flame coal (LFC) and collectors (kerosene, diesel, diethyl phthalate (DEP), biodiesel collector (BDC), and emulsified biodiesel collector (EBDC)) were analyzed via the density functional theory (DFT). The molecular dynamics (MD) of the coal−collector−water system and the adsorption of collectors on LFC were conducted based on the first principles. The results showed that the frontier molecular orbitals of kerosene, diesel, DEP, and BDC were 0.38 eV, 0.28 eV, 0.27 eV, and 0.20 eV, respectively. The chemical reactivity order of the above mentioned collectors was BDC > DEP > diesel > kerosene. Kerosene, diesel, and DEP adsorbed with carbonyl, hydroxyl, and carboxyl groups in LFC, respectively. Carboxyl groups in BDC and carboxyl groups in LFC bilaterally adsorbed, while BDC repelled water molecules via hydrogen bonds on the LFC surface. In the systems of BDC and EBDC, the diffusion coefficients of a water molecule were 2.83 × 10−4 cm2/s and 3.73 × 1... [more]
A Review of Nano and Microscale Heat Transfer: An Experimental and Molecular Dynamics Perspective
Samyabrata Chatterjee, Paras, Han Hu, Monojit Chakraborty
February 10, 2024 (v1)
Keywords: force-fields, liquid thin-film, microelectronic devices, molecular dynamics, thermal transportation
Significant progress in the development of micro and nanoscale devices has been observed for the past three decades. The thermal transportation in these small-length scales varies significantly, and it is difficult to explain the underlying physics using the pre-existing theoretical formulations. When the bulk dimension of a system is comparable to or smaller than the mean free path (MFP) of the thermal carriers, classical theories, such as Fourier’s Law of heat conduction, are unable to accurately explain the system energy dynamics. The phenomena of energy transit and conversion at the micro to nanoscale is an interesting topic of research due to the substantial changes in behavior that are documented when compared to those at the macro size. This review article is broadly divided into two parts. Initially, the recent development in the field of molecular dynamic (MD) simulations is emphasized. Classical MD simulation is such a powerful tool that provides insight into the length scale... [more]
Design and Implementation of Defect Detection System Based on YOLOv5-CBAM for Lead Tabs in Secondary Battery Manufacturing
Jisang Mun, Jinyoub Kim, Yeji Do, Hayul Kim, Chegyu Lee, Jongpil Jeong
February 10, 2024 (v1)
Keywords: automatic defect detection, CBAM, computer vision, deep learning, lead tap, object detection, YOLOv5
According to QYResearch, a global market research firm, the global market size of secondary batteries is growing at an average annual rate of 8.1%, but fires and casualties continue to occur due to the lack of quality and reliability of secondary batteries. Therefore, improving the quality of secondary batteries is a major factor in determining a company’s competitive advantage. In particular, lead taps, which electrically connect the negative and positive electrodes of secondary batteries, are a key factor in determining the stability of the battery. Currently, the quality inspection of secondary battery lead tab manufacturers mostly consists of visual inspection after vision inspection with a rule-based algorithm, which has limitations on the types of defects that can be detected, and the inspection time is increasing due to overlapping inspections, which is directly related to productivity. Therefore, this study aims to automate the quality inspection of lead tabs of secondary batte... [more]
Exploring Partial Structural Disorder in Anhydrous Paraxanthine through Combined Experiment, Solid-State Computational Modelling, and Molecular Docking
Jolanta Natalia Latosińska, Magdalena Latosińska, Janez Seliger, Veselko Žagar
February 10, 2024 (v1)
Keywords: binding mode of paraxanthine with A2A receptor, disorder, hydrogen bonds, methyl rotation, molecular docking, molecular dynamics, non-covalent interactions, paraxanthine
Paraxanthine (PX), a major metabolite of caffeine, a protective agent against Alzheimer’s and Parkinson’s disease, and a promising drug for the treatment of post-COVID 2019 anosmia and ageusia, has been studied in the solid state and protein−ligand complex. Partial disorder in PX, caused by the methyl group at the N(7) position, has been modelled and discussed. The relationship between the unusual structural disorder and the propensity to form a specific system of non-covalent bonds was analyzed. Three 1H-14N NMR-NQR (nuclear magnetic resonance−nuclear quadrupole resonance) experimental techniques were used, namely multiple frequency sweeps, Larmor frequency scanning, and the two-frequency irradiation, followed by solid-state computational modelling (density functional theory, supplemented by quantum theory of atoms in molecules, 3D Hirshfeld surfaces, and reduced density gradient), and molecular docking approaches. New quantitative methods for estimating changes in the global pattern... [more]
Experimental and Computational Fluid Dynamic—CFD Analysis Simulation of Heat Transfer Using Graphene Nanoplatelets GNP/Water in the Double Tube Heat Exchanger
Carlos C. X. S. Lima, Alvaro A. V. Ochoa, José A. P. da Costa, Frederico D. de Menezes, João V. P. Alves, Julia M. G. A. Ferreira, Clara C. A. Azevedo, Paula S. A. Michima, Gustavo N. P. Leite
February 10, 2024 (v1)
Keywords: double tube heat exchangers, graphene, heat transfer, nanofluids
This study investigates and compares the experimental heat transfer performance and simulation via computational fluid dynamics (CFD) of graphene nanoplatelets (GNP) and water nanofluids GNP/water in the double-tube-type heat exchanger (DTHE). Tests were conducted with water/water and GNP/water fluids, with the nanofluid for the hot-fluid circuit and water for the cold-fluid circuit, with counterflow direction, varying the nanofluid concentrations by weight (wt%) at 0.0125%, 0.025%, and 0.050%, the operating temperature at 50 and 60 °C, and Reynolds numbers between 2000−6000. The results showed that 0.025 wt% GNP presented better thermal performance, with a 28% increase in the temperature gain. The 0.025 wt% GNP had slightly better performance for the Nusselt number (Nu), and the 0.05 wt% GNP had a slightly better thermal effectiveness. The comparison between the experimental values showed good agreement with those calculated by empirical correlations and the CFD model, with maximum an... [more]
Reducing the Environmental and Economic Consequences of Installing an Underground Collector and Increasing User Comfort with a New Geometry and Installation Method
Ľubomíra Gabániová, Dušan Kudelas
February 10, 2024 (v1)
Keywords: Computational Fluid Dynamics, ground collector, heat extraction, renewable energy sources
The installation of ground collectors often has several disadvantages for the user, despite future benefits in more ecological heating, namely the need for a large space for installation, which increases costs, and can also cause inconvenience later, for example, by keeping snow on the surface for a longer time. The goal of this paper was to find out with the help of simulations in ANSYS whether a collector with a different geometry and arrangement (vertical spiral with diameters of 6, 8 and 10 m), which would be more comfortable, cheaper, and also friendlier to the environment, would achieve performance similar to the classic geometry—meander. The initial results are relatively favorable and prove that there is room for optimization and improvement in this field. Verification of network sensitivity in all cases is 8% or less. In the current situation of the energy crisis, it is necessary to look for the possibilities of using heat pumps in cities and metropolises. The new geometry cou... [more]
Research on Data Collection Methods for Assembly Performance of Array Antennas in Digital Twin Workshops
Xuepeng Guo, Linyan Liu, Zhexin Wang, Huifen Wang, Xiaodong Du, Jiancheng Shi, Yue Wang
February 10, 2024 (v1)
Keywords: data collection, digital twin, multi-source heterogeneous data, OPC UA model
Aimed at the characteristics of multi-source heterogeneity and the rapid generation of data in digital twin workshops, as well as the current situation where communication protocols between equipment within the workshop vary greatly and are difficult to interconnect, a data integration method based on OPC UA is designed. Firstly, combining the process flow and data source characteristics of array antenna assembly, a data collection and transmission scheme based on OPC UA was designed. Secondly, a process information model of array antenna assembly was established to realize data perception and transmission and solve the difficulties of complex data structure, high real-time requirements, and heterogeneous data in digital twin workshop. Finally, the proposed method and model were applied to the performance prediction platform for an array antenna assembly process based on digital twins, achieving perception of process data during the assembly process of array antennas, and achieving per... [more]
Automated Shape and Process Parameter Optimization for Scaling Up Geometrically Non-Similar Bioreactors
Stefan Seidel, Fruhar Mozaffari, Rüdiger W. Maschke, Matthias Kraume, Regine Eibl-Schindler, Dieter Eibl
February 10, 2024 (v1)
Keywords: biochemical engineering, computational fluid dynamics (CFD), energy dissipation rate, HEK293, hydrodynamic stress, Kolmogorov length scale, open-source, Optimization, scale-up
Scaling bioprocesses remains a major challenge. Since it is physically impossible to increase all process parameters equally, a suitable scale-up strategy must be selected for a successful bioprocess. One of the most widely used criteria when scaling up bioprocesses is the specific power input. However, this represents only an average value. This study aims to determine the Kolmogorov length scale distribution by means of computational fluid dynamics (CFD) and to use it as an alternative scale-up criterion for geometrically non-similar bioreactors for the first time. In order to obtain a comparable Kolmogorov length scale distribution, an automated geometry and process parameter optimization was carried out using the open-source tools OpenFOAM and DAKOTA. The Kolmogorov−Smirnov test statistic was used for optimization. A HEK293-F cell expansion (batch mode) from benchtop (Infors Minifors 2 with 4 L working volume) to pilot scale (D-DCU from Sartorius with 30 L working volume) was carri... [more]
Using Adsorption Energy Distribution for Parameter Estimation of Competitive Cofactor Coupled Enzyme Reaction
Thomas Waluga, Mirko Skiborowski
January 12, 2024 (v1)
Keywords: adsorption energy distribution, alcohol dehydrogenase, kinetic modeling
The chemical and biotechnology industries are facing new challenges in the use of renewable resources. The complex nature of these materials requires the use of advanced techniques to understand the kinetics of reactions in this context. This study presents an interdisciplinary approach to analyze cofactor coupled enzymatic two-substrate kinetics and competitive two-substrate kinetics in a fast and efficient manner. By studying the adsorption energy distribution (AED), it is possible to determine the individual parameters of the reaction kinetics. In the case of a single alcohol reaction, the AED is able to identify parameters in agreement with the literature with few experimental data points compared to classical methods. In the case of a competitive reaction, AED analysis can automatically determine the number of competing substrates, whereas traditional nonlinear regression requires prior knowledge of this information for parameter identification.
Detection of Cotton Seed Damage Based on Improved YOLOv5
Zhicheng Liu, Long Wang, Zhiyuan Liu, Xufeng Wang, Can Hu, Jianfei Xing
January 12, 2024 (v1)
Keywords: algorithm, appearance inspection, crop seed sorting, deep learning, machine vision
The quality of cotton seed is of great significance to the production of cotton in the cotton industry. In order to reduce the workload of the manual sorting of cotton seeds and improve the quality of cotton seed sorting, this paper proposed an image-detection method of cotton seed damage based on an improved YOLOv5 algorithm. Images of cotton seeds with different degrees of damage were collected in the same environment. Cotton seeds of three different damage degrees, namely, undamaged, slightly damaged, and seriously damaged, were selected as the research objects. Labeling software was used to mark the images of these cotton seeds and the marked images were input into the improved YOLOv5s detection algorithm for appearance-based damage identification. The algorithm added the lightweight upsampling operator CARAFE to the original YOLOv5s detection algorithm and also improved the loss function. The experimental results showed that the mAP_0.5 value of the improved algorithm reached 99.5... [more]
Photo-Programmable Processes in Bithiophene−Azobenzene Monolayers on Gold Probed via Simulations
Vladyslav Savchenko, Moufdi Hadjab, Alexander S. Pavlov, Olga Guskova
January 12, 2024 (v1)
Keywords: azobenzene, charge transfer, chemisorbed monolayer, conjugated oligomer, molecular modeling, molecular switch, organic electronics, photoisomerization
In this study, we investigate the structural changes, electronic properties, and charge redistribution within azo-bithiophene (Azo-BT)-chemisorbed monolayers under different light stimuli using the density functional theory and molecular dynamics simulations. We consider two types of switches, Azo-BT and BT-Azo, with different arrangements of the Azo and BT blocks counting from the anchor thiol group. The chemisorbed monolayers of pure cis- and trans-isomers with a surface concentration of approximately 2.7 molecules per nm2 are modeled on a gold surface using the classical all-atom molecular dynamics. Our results reveal a significant shrinkage of the BT-Azo layer under UV illumination, whereas the thicknesses of the Azo-BT layer remain comparable for both isomers. This difference in behavior is attributed to the ordering of the trans-molecules in the layers, which is more pronounced for Azo-BT, leading to a narrow distribution of the inclination angle to the gold surface. Conversely,... [more]
Numerical Simulation Study on Vibration Reduction Effect of Flexible Cutting-Tooth Unit
Haitao Ren, Jingwei Xu, Xin Jia, Sheng Zhou, Chunxiao Zhou, Yingxin Yang, Qi Zhan
January 12, 2024 (v1)
Keywords: drilling speed, flexible cutting, impact dynamic load, PDC bit, rock breaking mechanism
Under the conditions of drilling in gravel-bearing and heterogeneous stratas, the movement and force of the PDC bit during drilling are highly unstable. Irregular impact loads often cause fatigue failures such as tooth fracture, tooth breakage and delamination of the composite sheet. Dynamic impact load is the main cause of fatigue failure of cutting-tooth, which seriously affects the rock-breaking performance of PDC bits. This paper proposes a flexible cutting tooth unit consisting of a central tooth, an elastic element, and a base. The technical concept of flexible-cutting rock breaking is to reduce the impact load amplitude suffered during the cutting process to a certain threshold range by setting elastic elements or reducing the support stiffness of the cutting tooth, so as to inhibit the expansion of micro defects caused by the impact dynamic load of cutting teeth and prolong the service life of drill bits. The finite-element models of flexible cutting teeth for rock cutting were... [more]
Boosting CO2 Uptake from Waste Concrete Powder Using Artificial Intelligence and the Marine Predators Algorithm
Hegazy Rezk, Ali Alahmer, Rania M. Ghoniem, Samer As’ad
January 12, 2024 (v1)
Keywords: ANFIS modeling, CO2 uptake, marine predators algorithm, mineral carbonation, waste concrete powder
Waste concrete powder (WCP) is emerging as a potential method of adoption for CO2 sequestration due to its ability to chemically react with carbon dioxide and trap it within its structure. This study explores the application of artificial intelligence (AI) and the Marine Predators Algorithm (MPA) to maximize the absorption of CO2 from waste concrete powder generated by recycling plants for building and demolition debris. Initially, a model is developed to assess CO2 uptake according to carbonation time (CT) and water-to-solid ratio (WSR), utilizing the adaptive neuro-fuzzy inference system (ANFIS) modeling approach. Subsequently, the MPA is employed to estimate the optimal values for CT and WSR, thereby maximizing CO2 uptake. A significant improvement in modeling accuracy is evident when the ANOVA method is replaced with ANFIS, leading to a substantial increase of approximately 19% in the coefficient of determination (R-squared) from 0.84, obtained through ANOVA, to an impressive 0.999... [more]
Simulation and Experimental Study on Vibrating Screen-Type Grain-Recovery Device with Upper Centrifugal Fan
Yanjun Li, Yanguang Gong, Yongtao Yu, Fuxiang Xie
January 12, 2024 (v1)
Keywords: CFD–EDEM, grain recovery, orthogonal experiment, virtual simulation
To solve the problem of grain loss caused by nibbling during the working process of the maize ear and stem harvesting machine, a vibrating screen-type grain-recovery device with an upper centrifugal fan was designed. The device mainly consists of a centrifugal fan and vibrating screen. The work process of the grain-recovery device is theoretically analyzed, and it is clarified that the turning of the bracts is the key to separating the bracts from the grains, and the design criteria of the vibrating screen are obtained. The CFD−EDEM coupled single-factor simulation experiment was carried out on the size of the vibrating screen sieve hole and the number of draft bars, and the motion posture of the bracts was simulated. Based on the previous CFD−EDEM coupled simulation study, the orthogonal experiment was carried out on the fan speed, vibration screen drive-shaft speed, and operation speed of the grain-recovery device. The orthogonal experimental results show that, when the fan speed is... [more]
Modeling of Continuous Slug Flow Cooling Crystallization towards Pharmaceutical Applications
Anne Cathrine Kufner, Michael Rix, Kerstin Wohlgemuth
January 12, 2024 (v1)
Keywords: active pharmaceutical ingredients, continuous crystallization, high-quality products, mechanistic modeling, slug flow crystallizer
The rising trend towards continuous production in the field of small-scale crystallization has generated many creative concepts for apparatuses for the production of active pharmaceutical ingredients. One of these promising apparatuses is the Slug Flow Crystallizer (SFC), which enables the adjustment of the particle size distribution and the achievement of high yields through its alternating slug flow. To realize and understand the crystallization inside the SFC, high experimental effort has been necessary until now. Therefore, a mechanistic model considering the hydrodynamics of slug flow, the energy and mass balances, and the crystallization phenomena of growth and agglomeration inside the apparatus was developed. Its purpose is to improve the understanding of the process, estimate the effects of operating parameters on target properties, and predict crystallization behavior for different substance systems with minimal experimental effort. Successful modeling was validated with exper... [more]
Design, Multi-Perspective Computational Investigations, and Experimental Correlational Studies on Conventional and Advanced Design Profile Modified Hybrid Wells Turbines Patched with Piezoelectric Vibrational Energy Harvester Devices for Coastal Regions
Janani Thangaraj, Senthil Kumar Madasamy, Parvathy Rajendran, Safiah Zulkifli, Rajkumar Rajapandi, Hussein A. Z. AL-bonsrulah, Beena Stanislaus Arputharaj, Hari Prasath Jeyaraj, Vijayanandh Raja
January 12, 2024 (v1)
Keywords: composite materials, Computational Fluid Dynamics, FEA, forced and free vibrations, FSI, hybrid energy, hydro-energy
This work primarily investigates the performance and structural integrity of the Wells turbines for power production in coastal locations and their associated unmanned vehicles. An innovative design procedure is imposed on the design stage of the Wells turbine and thus so seven different models are generated. In the first comprehensive investigation, these seven models underwent computational hydrodynamic analysis using ANSYS Fluent 17.2 for various coastal working environments such as hydro-fluid speeds of 0.34 m/s, 1.54 m/s, 12 m/s, and 23 m/s. After this primary investigation, the best-performing Wells turbine model has been imposed as the second comprehensive computational investigation for three unique design profiles. The imposed unique design profile is capable of enhancing the hydro-power by 15.19%. Two detailed, comprehensive investigations suggest the best Wells turbine for coastal location-based applications. Since the working environments are complicated, additional advance... [more]
Influence of Hydraulic Parameters on Multi-Stage Pulse Characteristics of Pressurized Pulsed Water Jet
Yangkai Zhang, Qian Li
January 12, 2024 (v1)
Keywords: dominant pulse, drive pressure, initial pressure of booster chamber, multi-stage pulse characteristics, pressurized pulsed water jet, recessive pulse
The multi-stage pulse competition of pressurized pulsed water jet becomes the initial pulse at the head tip, and hydraulic parameters are the key parameters that affect the characteristics of multiple pulses. Based on the ultra-high-speed imaging system, a pressurized pulsed water jet flow field capture system was constructed, and the effects of initial pressure and driving pressure of the pressurized chamber on the characteristics of multi-stage pulses were studied. The experimental results show that as the initial pressure of the booster chamber increases, the jet changes from a discontinuous state to a continuous state, and the multi-level pulse simultaneously changes from dominant multi-pulse to implicit multi-pulse; as the driving pressure increases, the initial spacing between the first pulse and the second pulse increases, and the peak velocity of the initial pulse gradually increases. At the same time, the location of the peak velocity also shifts away from the nozzle as the dr... [more]
Multiscale CFD Simulation of Multiphase Erosion Process in a Connecting Pipe of Industrial Polycrystalline Silicon Unit
Sheng Chen, Jiarui Shi, Jun Yuan, Meng He, Yongquan Li, Liyun Zhu, Juanbo Liu, Jiangyun Wang, Guoshan Xie
January 5, 2024 (v1)
Keywords: Computational Fluid Dynamics, energy-minimization multi-scale, erosion, multiphase, polycrystalline silicon
Severe erosion phenomena often occur in industrial polycrystalline silicon units, leading to hydrogen leakage accidents and affecting long-term operation. It is favorable to use a computational fluid dynamics (CFD) simulation with the dense discrete phase model (DDPM) and the sub-grid energy-minimization multi-scale (EMMS) drag model to improve the prediction accuracy of complex multiphase erosion phenomena in a connecting pipe of an industrial polycrystalline silicon unit. Furthermore, the effect of droplet the specularity coefficient on boundary conditions is thoroughly considered. The predicted erosion behaviors are consistent with industrial data. The effects of operations parameters were discussed with three-dimensional CFD simulation, including droplet size and hydrogen volume fraction on erosion behaviors. The results indicated that the non-uniform multiphase erosion flow behavior near the wall can be simulated accurately with the EMMS drag model in a coarse mesh. A suitable dro... [more]
Study on Sublimation Drying of Carrot and Simulation by Using Cellular Automata
Jiayuan Shao, Fan Jiao, Lili Nie, Ying Wang, Yihan Du, Zhenyu Liu
January 5, 2024 (v1)
Keywords: cellular automata, heat and mass transfer, sublimation drying
Vacuum freeze-dried products exhibit properties characteristic of porous media, rendering them superior in both drying and rehydration capabilities. However, the process of sublimation drying is constrained by its substantial time and energy costs. To comprehensively grasp its technological process and identify the optimal process parameters, the cellular automata method was employed for sublimation process simulation. Carrot slices, measuring 10 mm in thickness and 40 mm in radius, were selected for both simulation and experimentation. The sublimation process was characterized using a two-dimensional heat and mass transfer equation, inclusive of a dusty gas model. Additionally, a cellular automaton model was applied to simulate the mass transfer process, temperature, and moisture content changes in the sublimation drying stage. Then, the accuracy of the model was verified through experimentation. There was a remarkable alignment between simulation and experimental outcomes, with deter... [more]
Numerical Investigation of the Electro-Thermo Convection in an Inclined Cavity Filled with a Dielectric Fluid
Dalila Akrour, Mohamed Issam Elkhazen, Walid Hassen, Karim Kriaa, Chemseddine Maatki, Bilel Hadrich, Lioua Kolsi
January 5, 2024 (v1)
Keywords: buoyancy forces, cavity inclination, electric field, electro-thermo-convection, finite volume method, numerical simulation
The present work is a numerical analysis of electro-thermo convection, occurring in a square differentially heated cavity filled with a dielectric fluid. The cavity experiences the combined effects of viscous, electrical, and thermal forces. The equations modelling the physical problem are solved via the finite volume approach. The study focuses on the effect of cavity tilt on the fluid flow structure and thermal performance inside the enclosure under the action of an electric field. A parametric study was performed, where the tilt angle is getting varied between 0° and 90°, as well as the Rayleigh number (5000 ≤ Ra ≤ 250,000) and the electric field (0 ≤ T ≤ 800). Furthermore, the electric charge injection level C, the mobility M and the Prandtl Pr numbers were all adjusted to a value of 10. The obtained results demonstrate that the hydrodynamic and thermal fields are significantly impacted by the cavity inclination. In addition, regardless of the thermal Rayleigh’s number, high electr... [more]
Modeling of Oxidative Coupling of Methane for Manufacture of Olefins—Part I: CFD Simulations
Tahyná B. Fontoura, Normando J. C. De Jesus, José Carlos Pinto
January 5, 2024 (v1)
Keywords: Computational Fluid Dynamics, fixed-bed reactors, heat and mass transfer, Olefins, oxidative coupling of methane
This paper presents a comprehensive computational fluid dynamics (CFD) model for describing the oxidative coupling of methane (OCM) carried out in fixed-bed reactors for olefin production. Initially, a single pellet model was developed and implemented to describe the heat and mass transfer within the pellet and between the gaseous and solid phases. Subsequently, sensitivity analyses were performed to assess the impact of pellet arrangement and feed conditions on the heat and mass transfer rates, subsequently affecting concentration and temperature profiles. As indicated by the simulations, a high ethylene content could be obtained with the increase in the CH4/O2 ratio, aligning well with previous experimental studies. Furthermore, it was observed that pellet arrangement can significantly affect the reactor performance. Additionally, the behavior of temperature and concentration in the gaseous and solid phases can be very different, such that pseudo-homogeneous modeling approaches shoul... [more]
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