Records with Subject: Modelling and Simulations
Showing records 1 to 25 of 442. [First] Page: 1 2 3 4 5 Last
Phenomenological Analysis of Thermo-Mechanical-Chemical Properties of GFRP during Curing by Means of Sensor Supported Process Simulation
Robert Hein, Robert Prussak, Jochen Schmidt
May 22, 2020 (v1)
Keywords: dielectric sensors, fiber bragg grating, process simulation, process-induced distortions, process-induced strains, reaction kinetic, residual stresses, viscoelasticity
Inherent process-induced deformations (PID) and residual stresses impede the application of composite parts. PID lead to a geometrical mismatch in assemblies and require subsequent work for tolerance compensation. Unknown residual stresses cause overweighted structures resulting from unnecessary high safety factors. To counteract the deformations, the tool design needs to be modified until the component geometry meets the specifications. This process is mostly carried out empirically and is time and cost intensive. To improve the efficiency of the development process, an in-deep comprehension of the manufacturing processes is mandatory. Therefore, experimental and simulation-based methods are increasingly applied and enhanced. The object of this work is to investigate the development of process-induced strains as well as the material behaviour during the manufacturing for a GFRP plate. The process-induced strains are monitored by optical fiber Bragg grating (FBG) sensors. The change of... [more]
Finite Element Analysis in Setting of Fillings of V-Shaped Tooth Defects Made with Glass-Ionomer Cement and Flowable Composite
Tsanka Dikova, Tihomir Vasilev, Vesela Hristova, Vladimir Panov
May 22, 2020 (v1)
Keywords: FEA, fillings, flowable composite, glass-ionomer cement, V-shaped tooth defects
The aim of the present paper is to investigate the deformation−stress state of fillings of V-shaped tooth defects by finite element analysis (FEA). Two different materials are used—auto-cured resin-reinforced glass-ionomer cement (GIC) and flowable photo-cured composite (FPC). Two materials are placed into the cavity in one portion, as before the application of the composite the cavity walls are covered with a thin adhesive layer. Deformations and equivalent von Mises stresses are evaluated by FEA. Experimental study of micro-leakage is performed. It is established that there is an analogous non-homogeneous distribution of equivalent Von Mises stresses at fillings of V-shaped defects, made with GIC and FPC. Maximum stresses are generated along the boundaries of the filling on the vestibular surface of the tooth and at the bottom of the filling itself. Values of equivalent Von Mises stresses of GIC fillings are higher than that of FPC. Magnitude and character of deformation distribution... [more]
Steady-State Water Drainage by Oxygen in Anodic Porous Transport Layer of Electrolyzers: A 2D Pore Network Study
Haashir Altaf, Nicole Vorhauer, Evangelos Tsotsas, Tanja Vidaković-Koch
May 22, 2020 (v1)
Keywords: drainage invasion, electrolysis, pore network model, pore size distribution, porous transport layer
Recently, pore network modelling has been attracting attention in the investigation of electrolysis. This study focuses on a 2D pore network model with the purpose to study the drainage of water by oxygen in anodic porous transport layers (PTL). The oxygen gas produced at the anode catalyst layer by the oxidation of water flows counter currently to the educt through the PTL. When it invades the water-filled pores of the PTL, the liquid is drained from the porous medium. For the pore network model presented here, we assume that this process occurs in distinct steps and applies classical rules of invasion percolation with quasi-static drainage. As the invasion occurs in the capillary-dominated regime, it is dictated by the pore structure and the pore size distribution. Viscous and liquid film flows are neglected and gravity forces are disregarded. The curvature of the two-phase interface within the pores, which essentially dictates the invasion process, is computed from the Young Laplace... [more]
Studies on Influence of Cell Temperature in Direct Methanol Fuel Cell Operation
R. Govindarasu, S. Somasundaram
May 22, 2020 (v1)
Keywords: catalyst, direct methanol fuel cell, membrane electrode assembly, methanol crossover, power density
Directmethanol fuel cells (DMFCs) offer one of the most promising alternatives for the replacement of fossil fuels. A DMFC that had an active Membrane Electrode Assembly (MEA) area of 45 cm2, a squoval-shaped manifold hole design, and a Pt-Ru/C catalyst combination at the anode was taken for analysis in simulation and real-time experimentation. A mathematical model was developed using dynamic equations of a DMFC. Simulation of a DMFC model using MATLAB software was carried out to identify the most influencing process variables, namely cell temperature, methanol flow rate and methanol concentration during a DMFC operation. Simulation results were recorded and analyzed. It was observed from the results that the cell temperature was the most influencing process variable in the DMFC operation, more so than the methanol flow rate and the methanol concentration. In the DMFC, real-time experimentation was carried out at different cell temperatures to find out the optimum temperature at which... [more]
Impact of Varying Load Conditions and Cooling Energy Comparison of a Double-Inlet Pulse Tube Refrigerator
Muhammad Arslan, Muhammad Farooq, Muhamamd Naqvi, Umair Sultan, Zia-ur-Rehman Tahir, Saad Nawaz, Nazim Waheed, Salman Raza Naqvi, Qasim Ali, M. Suleman Tariq, Ijaz Ahmad Chaudhry, John M. Anderson, Anthony Anukam
May 22, 2020 (v1)
Keywords: boundary conditions, fluent, pressure user define function, regenerator, two-dimensional simulation
Modeling and optimization of a double-inlet pulse tube refrigerator (DIPTR) is very difficult due to its geometry and nature. The objective of this paper was to optimize-DIPTR through experiments with the cold heat exchanger (CHX) along the comparison of cooling load with experimental data using different boundary conditions. To predict its performance, a detailed two-dimensional DIPTR model was developed. A double-drop pulse pipe cooler was used for solving continuity, dynamic and power calculations. External conditions for applicable boundaries include sinusoidal pressure from an end of the tube from a user-defined function and constant temperature or limitations of thermal flux within the outer walls of exchanger walls under colder conditions. The results of the system’s cooling behavior were reported, along with the connection between the mass flow rates, heat distribution along pulse tube and cold-end pressure, the cooler load’s wall temp profile and cooler loads with varied bound... [more]
Dual Solutions and Stability Analysis of Magnetized Hybrid Nanofluid with Joule Heating and Multiple Slip Conditions
Liang Yan, Sumera Dero, Ilyas Khan, Irshad Ali Mari, Dumitru Baleanu, Kottakkaran Sooppy Nisar, El-Sayed M. Sherif, Hany S. Abdo
May 22, 2020 (v1)
Keywords: dual solution, hybrid nanofluid, Joule heating, slip conditions, stability analysis
This paper investigates the steady, two dimensional, and magnetohydrodynamic flow of copper and alumina/water hybrid nanofluid on a permeable exponentially shrinking surface in the presence of Joule heating, velocity slip, and thermal slip parameters. Adopting the model of Tiwari and Das, the mathematical formulation of governing partial differential equations was constructed, which was then transformed into the equivalent system of non-linear ordinary differential equations by employing exponential similarity transformation variables. The resultant system was solved numerically using the BVP4C solver in the MATLAB software. For validation purposes, the obtained numerical results were compared graphically with those in previous studies, and found to be in good agreement, as the critical points are the same up to three decimal points. Based on the numerical results, it was revealed that dual solutions exist within specific ranges of the suction and magnetic parameters. Stability analysi... [more]
Study of Activation Energy on the Movement of Gyrotactic Microorganism in a Magnetized Nanofluids Past a Porous Plate
Muhammad Mubashir Bhatti, Anwar Shahid, Tehseen Abbas, Sultan Z Alamri, Rahmat Ellahi
May 22, 2020 (v1)
Keywords: bio-convection, electro-conductive polymer processing, gyrotactic microorganisms, porous media
The present study deals with the swimming of gyrotactic microorganisms in a nanofluid past a stretched surface. The combined effects of magnetohydrodynamics and porosity are taken into account. The mathematical modeling is based on momentum, energy, nanoparticle concentration, and microorganisms’ equation. A new computational technique, namely successive local linearization method (SLLM), is used to solve nonlinear coupled differential equations. The SLLM algorithm is smooth to establish and employ because this method is based on a simple univariate linearization of nonlinear functions. The numerical efficiency of SLLM is much powerful as it develops a series of equations which can be subsequently solved by reutilizing the data from the solution of one equation in the next one. The convergence was improved through relaxation parameters in the study. The accuracy of SLLM was assured through known methods and convergence analysis. A comparison of the proposed method with the existing lit... [more]
Thermal Behavior of a Rod during Hot Shape Rolling and Its Comparison with a Plate during Flat Rolling
Joong-Ki Hwang
May 22, 2020 (v1)
Keywords: flat rolling, shape rolling, temperature distribution, wire rod
The thermal behavior of a rod during the hot shape rolling process was investigated using the off-line hot rolling simulator and numerical simulation. Additionally, it was compared with a plate during the flat rolling process to understand the thermal behavior of the rod during the hot rolling process in more detail. The temperature of the rod and plate during the hot rolling process was measured at several points with thermocouples using the rolling simulator, and then the measured temperature of each region of a workpiece was analyzed with numerical simulation. During hot rolling process, the temperature distribution of the rod was very different from the plate. The temperature deviation of the rod with area was much higher than that of the plate. The variation in effective stress of the rod along the circumferential direction can induce the temperature difference with area of the rod, whereas the plate had a relatively lower temperature deviation with area due to the uniform effecti... [more]
Multi-Agent Systems and Complex Networks: Review and Applications in Systems Engineering
Manuel Herrera, Marco Pérez-Hernández, Ajith Kumar Parlikad, Joaquín Izquierdo
May 18, 2020 (v1)
Keywords: agent-based control, complex networks, multi-agent systems, optimisation, processes systems engineering, systems engineering
Systems engineering is an ubiquitous discipline of Engineering overlapping industrial, chemical, mechanical, manufacturing, control, software, electrical, and civil engineering. It provides tools for dealing with the complexity and dynamics related to the optimisation of physical, natural, and virtual systems management. This paper presents a review of how multi-agent systems and complex networks theory are brought together to address systems engineering and management problems. The review also encompasses current and future research directions both for theoretical fundamentals and applications in the industry. This is made by considering trends such as mesoscale, multiscale, and multilayer networks along with the state-of-art analysis on network dynamics and intelligent networks. Critical and smart infrastructure, manufacturing processes, and supply chain networks are instances of research topics for which this literature review is highly relevant.
Multiobjective Combination Optimization of an Impeller and Diffuser in a Reversible Axial-Flow Pump Based on a Two-Layer Artificial Neural Network
Fan Meng, Yanjun Li, Shouqi Yuan, Wenjie Wang, Yunhao Zheng, Majeed Koranteng Osman
May 18, 2020 (v1)
Keywords: Computational Fluid Dynamics, multiobjective optimization, reversible axial-flow pump, Surrogate Model, two-layer ANN
This study proposed a kind of optimization design for a reversible axial-flow pump based on an ordinary one-way pump. Three-dimensional (3D) Reynolds-averaged Navier−Stokes (RANS) equations was used to predict the pump performance, and the optimized design was validated by an external characteristic test. Six main geometry parameters of an impeller and diffuser based on an orthogonal experiment were set as design variables. The efficiency and head under forward and reverse design conditions were set as the optimization objective. Based on 120 groups of sample designs obtained from Latin hypercube sampling (LHS), a two-layer artificial neural network (ANN) was used to build a non-linear function with high accuracy between the design variables and optimization objective. The optimized design was obtained from 300 groups of Pareto-optimal solutions using the non-dominated based genetic algorithm (NSGA) for multiobjective optimization. After optimization, there was a slight decrease in the... [more]
Identification of the Interfacial Surface in Separation of Two-Phase Multicomponent Systems
Ivan Pavlenko, Oleksandr Liaposhchenko, Vsevolod Sklabinskyi, Vitaly Storozhenko, Yakov Mikhajlovskiy, Marek Ochowiak, Vitalii Ivanov, Jan Pitel, Oleksandr Starynskyi, Sylwia Włodarczak, Andżelika Krupińska, Małgorzata Markowska
May 18, 2020 (v1)
Keywords: contact area ratio, fractional distribution, heat and mass transfer, multiphase flow, probabilistic approach, separation
The area of the contact surface of phases is one of the main hydrodynamic indicators determining the separation and heat and mass transfer equipment calculations. Methods of evaluating this indicator in the separation of multicomponent two-phase systems were considered. It was established that the existing methods for determining the interfacial surface are empirical ones, therefore limited in their applications. Consequently, the use of the corresponding approaches is appropriate for certain technological equipment only. Due to the abovementioned reasons, the universal analytical formula for determining the interfacial surface was developed. The approach is based on both the deterministic and probabilistic mathematical models. The methodology was approved on the example of separation of two-phase systems considering the different fractional distribution of dispersed particles. It was proved that the area of the contact surface with an accuracy to a dimensionless ratio depends on the v... [more]
Investigation of the Superposition Effect of Oil Vapor Leakage and Diffusion from External Floating-Roof Tanks Using CFD Numerical Simulations and Wind-Tunnel Experiments
Jie Fang, Weiqiu Huang, Fengyu Huang, Lipei Fu, Gao Zhang
May 18, 2020 (v1)
Keywords: external floating-roof tank, leakage and diffusion, numerical simulation, oil vapor superposition effect, wind tunnel
Based on computational fluid dynamics (CFD) and Realizable k-ε turbulence model, we established a numerical simulation method for wind and vapor-concentration fields of various external floating-roof tanks (EFRTs) (single, two, and four) and verified its feasibility using wind-tunnel experiments. Subsequently, we analysed superposition effects of wind speed and concentration fields for different types of EFRTs. The results show that high concentrations of vapor are found near the rim gap of the floating deck and above the floating deck surface. At different ambient wind speeds, interference between tanks is different. When the ambient wind speed is greater than 2 m/s, vapor concentration in leeward area of the rear tank is greater than that between two tanks, which makes it easy to reach explosion limit. It is suggested that more monitoring should be conducted near the bottom area of the rear tank and upper area on the left of the floating deck. Superposition in a downwind direction fr... [more]
Numerical Investigation of Centrifugal Blood Pump Cavitation Characteristics with Variable Speed
Teng Jing, Yujiao Cheng, Fangqun Wang, Wei Bao, Ling Zhou
May 18, 2020 (v1)
Keywords: cavitation, centrifugal blood pump, multi-scale modeling, variable speed assist
In this paper, the cavitation characteristics of centrifugal blood pumps under variable speeds were studied by using ANSYS-CFX and MATLAB software. The study proposed a multi-scale model of the “centrifugal blood pump—left heart blood circulation”, and analyzed the cavitation characteristics of the centrifugal blood pump. The results showed that the cavitation in the impeller first appeared near the hub at the inlet of the impeller. As the inlet pressure decreased, the cavitation gradually strengthened and the bubbles gradually developed in the outlet of the impeller. The cavitation intensity increased with the increase of impeller speed. The curve of the variable speeds of the centrifugal blood pump in the optimal auxiliary state was obtained, which could effectively improve the aortic pressure and flow. In variable speeds, due to the high aortic flow and pressure during the ejection period, the sharp increases in speeds led to cavitation. The results could provide a guidance for the... [more]
Cu-Al2O3 Water Hybrid Nanofluid Transport in a Periodic Structure
Aiman Alshare, Wael Al-Kouz, Waqar Khan
May 8, 2020 (v1)
Keywords: Cu-Al2O3, heat transfer augmentation, hybrid nanofluid, nanofluid, periodic, wavy channel
The present work is a computational investigation of nanofluid and hybrid nanofluid transport in a periodic structure. The governing equations for this work along with the appropriate boundary conditions are solved using the finite-volume method. The simulations are carried out using five wavy amplitudes of the channel shape for a range of Reynolds numbers from 102 to103. It is found that increasing the amplitude and increasing the nanoparticle volume fraction achieve enhancement of the heat transfer at the cost of increased pumping power. Correlations for the friction factor and the Nusselt number for both fluid types are provided.
Numerical Simulation of Cavitation Performance in Engine Cooling Water Pump Based on a Corrected Cavitation Model
Wei Li, Enda Li, Weidong Shi, Weiqiang Li, Xiwei Xu
May 8, 2020 (v1)
Keywords: cavitation model, engine cooling water pump, numerical simulation, thermodynamic effect, unsteady process
To analyze the internal flow of the engine cooling water pump (ECWP) under thermodynamic effect, Zwart cavitation model based on the Rayleigh-Plesset equation is corrected, and NACA0015 hydrofoil was selected to verify the corrected model. The cavitation performances of ECWP with different temperatures were numerically simulated based on a corrected cavitation model. Research results show that simulation values of pressure distribution coefficient in hydrofoil surface at 70 °C are in closest agreement with experimental values when the evaporation and condensation coefficients are 10 and 0.002, respectively. With the decrease of absolute pressure in pump inlet, bubbles firstly occurred at the blade inlet side near the suction surface and then gradually extended to the pressure surface, finally clogged the impeller passage. Compared to the inlet section, the cavitation degree is much more serious close to the trailing edge. With the temperature increases, the cavitation in ECWP occurs in... [more]
Oxidative Coupling of Methane in Membrane Reactors; A Techno-Economic Assessment
Aitor Cruellas, Jelle Heezius, Vincenzo Spallina, Martin van Sint Annaland, José Antonio Medrano, Fausto Gallucci
May 8, 2020 (v1)
Keywords: chemical processes, fuel-switching scenario, membrane reactors, methane coupling, Modelling, oxygen selective membrane, Technoeconomic Analysis
Oxidative coupling of methane (OCM) is a process to directly convert methane into ethylene. However, its ethylene yield is limited in conventional reactors by the nature of the reaction system. In this work, the integration of different membranes to increase the overall performance of the large-scale oxidative coupling of methane process has been investigated from a techno-economic point of view. A 1D membrane reactor model has been developed, and the results show that the OCM reactor yield is significantly improved when integrating either porous or dense membranes in packed bed reactors. These higher yields have a positive impact on the economics and performance of the downstream separation, resulting in a cost of ethylene production of 595−625 €/tonC2H4 depending on the type of membranes employed, 25−30% lower than the benchmark technology based on oil as feedstock (naphtha steam cracking). Despite the use of a cryogenic separation unit, the porous membranes configuration shows gener... [more]
Simulation of Solid Oxide Fuel Cell Anode in Aspen HYSYS—A Study on the Effect of Reforming Activity on Distributed Performance Profiles, Carbon Formation, and Anode Oxidation Risk
Khaliq Ahmed, Amirpiran Amiri, Moses O. Tadé
May 2, 2020 (v1)
Keywords: anode oxidation, carbon formation, internal reforming, Simulation, SOFC
A distributed variable model for solid oxide fuel cell (SOFC), with internal fuel reforming on the anode, has been developed in Aspen HYSYS. The proposed model accounts for the complex and interactive mechanisms involved in the SOFC operation through a mathematically viable and numerically fast modeling framework. The internal fuel reforming reaction calculations have been carried out in a plug flow reactor (PFR) module integrated with a spreadsheet module to interactively calculate the electrochemical process details. By interlinking the two modules within Aspen HYSYS flowsheeting environment, the highly nonlinear SOFC distributed profiles have been readily captured using empirical correlations and without the necessity of using an external coding platform, such as MATLAB or FORTRAN. Distributed variables including temperature, current density, and concentration profiles along the cell length, have been discussed for various reforming activity rates. Moreover, parametric estimation of... [more]
Research on Flow Characteristics of Straight Line Conjugate Internal Meshing Gear Pump
Hongqiang Chai, Guolai Yang, Guoguo Wu, Guixiang Bai, Wenqi Li
May 2, 2020 (v1)
Keywords: average flow rate, flow pulsation, gear pair’s geometric parameters, performance evaluations, simulation analysis, straight line conjugate internal meshing gear pump
The improvement of the overall performance of hydraulic pumps is the basis of intelligent hydraulics. Taking the straight line conjugate internal meshing gear pump as the research object, the theoretical flow rate and the geometric flow pulsation rate equations are established in this study through the volume change method. The change laws of the gear pair’s geometric parameters on the theoretical flow rate and the geometric flow pulsation rate are studied. The simulation model of the internal flow channel is established, and the influence factors and the influence degree of the flow pulsation and average flow rate are analyzed. The high-pressure positive displacement pump test system is also designed and built. The performance evaluations are conducted, and the experimental results are analyzed. The results show that the periodic change of the meshing point position is the root cause of the geometric flow pulsation. The theoretical flow rate and the geometric flow pulsation rate are 1... [more]
Numerical Analysis of High-Pressure Direct Injection Dual-Fuel Diesel-Liquefied Natural Gas (LNG) Engines
Alberto Boretti
May 2, 2020 (v1)
Keywords: compression ignition, cryogenic gas, diesel engines, direct injection, dual fuel engines, greenhouse gas emissions, Natural Gas, particulate matter
Dual fuel engines using diesel and fuels that are gaseous at normal conditions are receiving increasing attention. They permit to achieve the same (or better) than diesel power density and efficiency, steady-state, and substantially similar transient performances. They also permit to deliver better than diesel engine-out emissions for CO2, as well as particulate matter, unburned hydrocarbons, and nitrous oxides. The adoption of injection in the liquid phase permits to further improve the power density as well as the fuel conversion efficiency. Here, a model is developed to study a high-pressure, 1600 bar, liquid phase injector for liquefied natural gas (LNG) in a high compression ratio, high boost engine. The engine features two direct injectors per cylinder, one for the diesel and one for the LNG. The engine also uses mechanically assisted turbocharging (super-turbocharging) to improve the steady-state and transient performances of the engine, decoupling the power supply at the turbin... [more]
3D Magneto-Buoyancy-Thermocapillary Convection of CNT-Water Nanofluid in the Presence of a Magnetic Field
Lioua Kolsi, Salem Algarni, Hussein A. Mohammed, Walid Hassen, Emtinene Lajnef, Walid Aich, Mohammed A. Almeshaal
May 2, 2020 (v1)
Keywords: buoyancy thermocapillary convection, CNT-water nanofluid, flow control., magnetic field direction, Marangoni number
A numerical study is performed to investigate the effects of adding Carbon Nano Tube (CNT) and applying a magnetic field in two directions (vertical and horizontal) on the 3D-thermo-capillary natural convection. The cavity is differentially heated with a free upper surface. Governing equations are solved using the finite volume method. Results are presented in term of flow structure, temperature field and rate of heat transfer. In fact, results revealed that the flow structure and heat transfer rate are considerably affected by the magnitude and the direction of the magnetic field, the presence of thermocapillary forces and by increasing nanoparticles volume fraction. In opposition, the increase of the magnetic field magnitude leads to the control the flow causing flow stabilization by merging vortexes and reducing heat transfer rate.
Fluid−Solid Coupling Model and Simulation of Gas-Bearing Coal for Energy Security and Sustainability
Shixiong Hu, Xiao Liu, Xianzhong Li
April 14, 2020 (v1)
Keywords: coal containing gas, energy safety, fluid–solid coupling, permeability, Renewable and Sustainable Energy
The optimum design of gas drainage boreholes is crucial for energy security and sustainability in coal mining. Therefore, the construction of fluid−solid coupling models and numerical simulation analyses are key problems for gas drainage boreholes. This work is based on the basic theory of fluid−solid coupling, the correlation definition between coal porosity and permeability, and previous studies on the influence of adsorption expansion, change in pore free gas pressure, and the Klinkenberg effect on gas flow in coal. A mathematical model of the dynamic evolution of coal permeability and porosity is derived. A fluid−solid coupling model of gas-bearing coal and the related partial differential equation for gas migration in coal are established. Combined with an example of the measurement of the drilling radius of the bedding layer in a coal mine, a coupled numerical solution under negative pressure extraction conditions is derived by using COMSOL Multiphysics simulation software. Numer... [more]
Numerical Analysis on Velocity and Temperature of the Fluid in a Blast Furnace Main Trough
Yao Ge, Meng Li, Han Wei, Dong Liang, Xuebin Wang, Yaowei Yu
April 14, 2020 (v1)
Keywords: conjugate heat transfer, main trough, refractory, transient fluid of hot metal and molten slag, wall shear stress
The main trough is a part of the blast furnace process for hot metal and molten slag transportation from the tap hole to the torpedo, and mechanical erosion of the trough is an important reason for a short life of a campaign. This article employed OpenFoam code to numerically study and analyze velocity, temperature and wall shear stress of the fluids in the main trough during a full tapping process. In the code, a three-dimensional transient mass, momentum and energy conservation equations, including the standard k-ε turbulence model, were developed for the fluid in the trough. Temperature distribution in refractory is solved by the Fourier equation through conjugate heat transfer with the fluid in the trough. Change velocities of the fluid during the full tapping process are exactly described by a parabolic equation. The investigation results show that there are strong turbulences at the area of hot metal’s falling position and the turbulences have influence on velocity, temperature a... [more]
Isolated Taylor Bubbles in Co-Current with Shear Thinning CMC Solutions in Microchannels—A Numerical Study
Ana I. Moreira, Luís A. M. Rocha, João Carneiro, José D. P. Araújo, João B. L. M. Campos, João M. Miranda
April 14, 2020 (v1)
Keywords: carboxymethylcellulose solutions, Computational Fluid Dynamics, microfluidics, shear thinning fluids, Taylor bubbles, volume of fluid method
Slug flow is a multiphase flow pattern characterized by the occurrence of long gas bubbles (Taylor bubbles) separated by liquid slugs. This multiphase flow regime is present in many and diversified natural and industrial processes, at macro and microscales, such as in eruption of volcanic magmas, oil recovery from pre-salt regions, micro heat exchangers, and small-sized refrigerating systems. Previous studies in the literature have been mostly focused on tubular gas bubbles flowing in Newtonian liquids. In this work, results from several numerical simulations of tubular gas bubbles flowing in a shear thinning liquid in microchannels are reported. To simulate the shear thinning behavior, carboxymethylcellulose (CMC) solutions with different concentrations were considered. The results are compared with data from bubbles flowing in Newtonian liquids in identical geometric and dynamic conditions. The numerical work was carried out in computational fluid dynamics (CFD) package Ansys Fluent... [more]
Influence of Soil Particle Size on the Temperature Field and Energy Consumption of Injected Steam Soil Disinfection
Zhenjie Yang, Adnan Abbas, Xiaochan Wang, Muhammad Ameen, Haihui Yang, Shakeel Ahmed Soomro
April 14, 2020 (v1)
Keywords: energy consumption, soil particle size, soil steam disinfection, soil temperature, soil water content
Soil steam disinfection (SSD) technology is an effective means of eliminating soil borne diseases. Among the soil cultivation conditions of facility agriculture in the Yangtze River Delta region of China, the clay soil particles (SPs) are fine, the soil pores are small, and the texture is relatively viscous. When injection disinfection technology is applied in the clay soil, the diffusion of steam is hindered and the heating efficiency is substantially affected. To increase the heating efficiency of SSD, we first discretized the continuum model of Philip and De Vries into circular particle porous media of different sizes and random distribution. Then with Computational Fluid Dynamics (CFD) numerical simulation technology, a single-injection steam disinfection model for different SP size conditions was constructed. Furthermore, the diffusion pattern of the macro-porous vapor flow and matrix flow and the corresponding temperature field were simulated and analyzed. Finally, a single-pipe... [more]
A Mathematical Model Combined with Radar Data for Bell-Less Charging of a Blast Furnace
Meng Li, Han Wei, Yao Ge, Guocai Xiao, Yaowei Yu
April 14, 2020 (v1)
Keywords: blast furnace, burden distribution, charging system, mathematical model, radar data
Charging directly affects the burden distribution of a blast furnace, which determines the gas distribution in the shaft of the furnace. Adjusting the charging can improve the distribution of the gas flow, increase the gas utilization efficiency of the furnace, reduce energy consumption, and prolong the life of the blast furnace. In this paper, a mathematical model of blast furnace charging was developed and applied on a steel plant in China, which includes the display of the burden profile, burden layers, descent speed of the layers, and ore/coke ratio. Furthermore, the mathematical model is developed to combine the radar data of the burden profile. The above model is currently used in Nanjing Steel as a reference for operators to adjust the charging. The model is being tested with a radar system on the blast furnace.
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