EFFECTS OF OPERATING CONDITIONS ON THE DEPOSITION OF GaAs IN A VERTICAL CVD REACTOR

2008 ◽  
Vol 15 (01n02) ◽  
pp. 111-116 ◽  
Author(s):  
JAE-SANG BAEK ◽  
JIN-HYO BOO ◽  
YOUN-JEA KIM
Keyword(s):  
Fluid Transport ◽  
Numerical Study ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Rotation Velocity ◽  
Operating Conditions ◽  
Deposition Condition ◽  
Three Dimensional Model ◽  
Trimethyl Gallium ◽  
Vertical Cvd Reactor

A numerical study is needed to gain insight into the growth mechanism and improve the reactor design or optimize the deposition condition in chemical vapor deposition (CVD). In this study, we have performed a numerical analysis of the deposition of gallium arsenide ( GaAs ) from trimethyl gallium (TMG) and arsine in a vertical CVD reactor. The effects of operating parameters, such as the rotation velocity of susceptor, inlet velocity, and inlet TMG fraction, are investigated and presented. The three-dimensional model which is used in this investigation includes complete coupling between the thermal-fluid transport and species transport with chemical reaction.

Fabrication of GaN Films in a Chemical Vapor Deposition Reactor

2013 ◽  
Author(s):  
J. Meng ◽  
Y. Jaluria ◽  
S. Wong
Keyword(s):  
Growth Rate ◽  
Film Growth ◽  
Numerical Study ◽  
Three Dimensional ◽  
Chemical Vapor ◽  
Rotating Disk ◽  
Transport Processes ◽  
Operating Conditions ◽  
Fluid Loss ◽  
Flow Recirculation

A three-dimensional numerical study has been carried out on the rotating disk GaN MOCVD process, and it is also coupled with an experimental study on the flow and thermal transport processes in the system. An impingement type reactor, with a rotating base, is considered. The dependence of the thin film growth rate and uniformity on operating conditions such as inflow velocity, rotational speed, and susceptor temperature are investigated in detail. Similarly, the effect of the geometry and configuration of the reactor are studied. The study also considers the effect of thermal and solutal buoyancy on the resulting flow. The flow and the associated transport processes are discussed in detail on the basis of the results obtained to suggest approaches to improve the uniformity of the film, minimize fluid loss and reduce flow recirculation that could affect growth rate and uniformity.

Numerical Simulation of Gas Flow and Heat Transfer in Cross-Wavy Primary Surface Channel for Microtubine Recuperators

2005 ◽  
Author(s):  
H. X. Liang ◽  
Q. W. Wang ◽  
L. Q. Luo ◽  
Z. P. Feng
Keyword(s):  
Heat Transfer ◽  
Numerical Simulation ◽  
Gas Turbine ◽  
Numerical Study ◽  
High Reliability ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Flow And Heat Transfer ◽  
High Heat Transfer ◽  
The Cross

Three-dimensional numerical simulation was conducted to investigate the flow field and heat transfer performance of the Cross-Wavy Primary Surface (CWPS) recuperators for microturbines. Using high-effective compact recuperators to achieve high thermal efficiency is one of the key techniques in the development of microturbine in recent years. Recuperators need to have minimum volume and weight, high reliability and durability. Most important of all, they need to have high thermal-effectiveness and low pressure-losses so that the gas turbine system can achieve high thermal performances. These requirements have attracted some research efforts in designing and implementing low-cost and compact recuperators for gas turbine engines recently. One of the promising techniques to achieve this goal is the so-called primary surface channels with small hydraulic dimensions. In this paper, we conducted a three-dimensional numerical study of flow and heat transfer for the Cross-Wavy Primary Surface (CWPS) channels with two different geometries. In the CWPS configurations the secondary flow is created by means of curved and interrupted surfaces, which may disturb the thermal boundary layers and thus improve the thermal performances of the channels. To facilitate comparison, we chose the identical hydraulic diameters for the above four CWPS channels. Since our experiments on real recuperators showed that the Reynolds number ranges from 150 to 500 under the operating conditions, we implemented all the simulations under laminar flow situations. By analyzing the correlations of Nusselt numbers and friction factors vs. Reynolds numbers of the four CWPS channels, we found that the CWPS channels have superior and comprehensive thermal performance with high compactness, i.e., high heat transfer area to volume ratio, indicating excellent commercialized application in the compact recuperators.

On the numerical study of thermohydrodynamics and biochemistry of inland water bodies

2021 ◽  
Author(s):  
Daria Gladskikh ◽  
Evgeny Mortikov ◽  
Victor Stepanenko
Keyword(s):  
Mixed Layer ◽  
Numerical Study ◽  
Three Dimensional ◽  
Water Bodies ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
One Dimensional ◽  
Lake Model ◽  
Upper Mixed Layer ◽  
The One

<p>The study of thermodynamic and biochemical processes of inland water objects using one- and three-dimensional RANS numerical models was carried out both for idealized water bodies and using measurements data. The need to take into account seiche oscillations to correctly reproduce the deepening of the upper mixed layer in one-dimensional (vertical) models is demonstrated. We considered the one-dimensional LAKE model [1] and the three-dimensional model [2, 3, 4] developed at the Research Computing Center of Moscow State University on the basis of a hydrodynamic code combining DNS/LES/RANS approaches for calculating geophysical turbulent flows. The three-dimensional model was supplemented by the equations for calculating biochemical substances by analogy with the one-dimensional biochemistry equations used in the LAKE model. The effect of mixing processes on the distribution of concentration of greenhouse gases, in particular, methane and oxygen, was studied.</p><p>The work was supported by grants of the RF President’s Grant for Young Scientists (MK-1867.2020.5, MD-1850.2020.5) and by the RFBR (19-05-00249, 20-05-00776). </p><p>1. Stepanenko V., Mammarella I., Ojala A., Miettinen H., Lykosov V., Timo V. LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes // Geoscientific Model Development. 2016. V. 9(5). P. 1977–2006.<br>2. Mortikov E.V., Glazunov A.V., Lykosov V.N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure-strain correlations // Russian Journal of Numerical Analysis and Mathematical Modelling. 2019. 34(2). P. 119-132.<br>3. Mortikov, E.V. Numerical simulation of the motion of an ice keel in stratified flow // Izv. Atmos. Ocean. Phys. 2016. V. 52. P. 108-115.<br>4. Gladskikh D.S., Stepanenko V.M., Mortikov E.V. On the influence of the horizontal dimensions of inland waters on the thickness of the upper mixed layer // Water Resourses. 2021.V. 45, 9 pages. (in press) </p>

Strength Analysis and Optimization Methods for Four Cylinder Engine Crankshaft Based on CATIA and ANSYS

2014 ◽  
Vol 592-594 ◽  
pp. 1789-1793
Author(s):  
Amarjeet Singh ◽  
Vinod Kumar Mittal ◽  
Surjit Angra
Keyword(s):  
Static Analysis ◽  
Material Selection ◽  
Three Dimensional ◽  
Optimization Methods ◽  
Operating Conditions ◽  
Strength Analysis ◽  
Three Dimensional Model ◽  
Ic Engine ◽  
Stress Zone ◽  
Engine Crankshaft

Crankshaft is one of the most important components of an IC engine. Crankshaft should be checked carefully to ensure that its design is fully optimized. The main objective of this paper is to perform the static analysis on four cylinder engine crankshaft to find out its static strength and the maximum stress zone and analyzing the different methods for the optimization of crankshaft in terms of weight, stress and cost reduction. A three dimensional model of four cylinder engine crankshaft is prepared corresponding to actual conditions in Catia V5 software, static analysis is performed using Ansys under extreme operating conditions and the improvement methods for the optimum design are analyzed in terms of geometric improvement, appropriate material selection and methods used for manufacturing of crankshaft.

Experimental and Numerical Study of Cold Gas-Solid Flow Regimes in a Fluidized Bed Gasifier

2017 ◽  
Author(s):  
Anton Pylypenko ◽  
Yevgenii Rastigejev ◽  
Lijun Wang ◽  
Abolghasem Shahbazi
Keyword(s):  
Fluidized Bed ◽  
Numerical Study ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Silica Sand ◽  
State University ◽  
Solid Flow ◽  
Fluidized Bed Gasifier ◽  
Isothermal Gas ◽  
Cold Gas

The objective of this work is to analyze the dynamics and regimes of cold gas-solid flow in a biomass gasifier that is built at North Carolina Agricultural and Technical State University and to identify its corresponding ranges of operating conditions. The value of the minimum fluidization velocity Umf ≈ 8 cm/s has been found experimentally in a series of measurements of a pressure drop in the fluidized bed filled with Gledart type-B silica sand for the range of superficial gas velocities between 0 and 40 cm/s. To complement the experimental results, a set of three-dimensional numerical simulations of the isothermal gas-solid flow based on Eulerian-Eulerian approach has been performed. The analysis of the fluidization characteristics such as axial void fraction distributions has allowed us to evaluate the dependence of the bed expansion ratios from the flow superficial velocity. Good agreement between experimental and numerical results for the considered operating conditions of the gasifier has been observed.

scholarly journals Hydrodynamic Effects Produced by Submerged Breakwaters in a Coastal Area with a Curvilinear Shoreline

2019 ◽  
Vol 7 (10) ◽  
pp. 337 ◽  
Author(s):  
Francesco Gallerano ◽  
Giovanni Cannata ◽  
Federica Palleschi
Keyword(s):  
Coastal Area ◽  
Stokes Equations ◽  
Numerical Study ◽  
Three Dimensional ◽  
Integral Form ◽  
Navier Stokes ◽  
Hydrodynamic Effect ◽  
Riemann Solver ◽  
Three Dimensional Model ◽  
Navier Stokes Equations

A three-dimensional numerical study of the hydrodynamic effect produced by a system of submerged breakwaters in a coastal area with a curvilinear shoreline is proposed. The three-dimensional model is based on an integral contravariant formulation of the Navier-Stokes equations in a time-dependent curvilinear coordinate system. The integral form of the contravariant Navier-Stokes equations is numerically integrated by a finite-volume shock-capturing scheme which uses Monotonic Upwind Scheme for Conservation Laws Total Variation Diminishing (MUSCL-TVD) reconstructions and an Harten Lax van Leer Riemann solver (HLL Riemann solver). The numerical model is used to verify whether the presence of a submerged coastal defence structure, in the coastal area with a curvilinear shoreline, is able to modify the wave induced circulation pattern and the hydrodynamic conditions from erosive to accretive.

Numerical modelling of a microreactor for thermocatalytic decomposition of toxic compounds

2011 ◽  
Vol 32 (3) ◽  
pp. 215-227 ◽  
Author(s):  
Paweł Jóźwik ◽  
Michał Karcz ◽  
Janusz Badur
Keyword(s):  
Numerical Modelling ◽  
Knudsen Diffusion ◽  
Three Dimensional ◽  
Operating Conditions ◽  
Three Dimensional Model ◽  
Toxic Compounds ◽  
Slip Boundary ◽  
Standard Models ◽  
Thermocatalytic Decomposition

Numerical modelling of a microreactor for thermocatalytic decomposition of toxic compounds In this paper a three-dimensional model for determination of a microreactor's length is presented and discussed. The reaction of thermocatalytic decomposition has been implemented on the base of experimental data. Simplified Reynolds-Maxwell formula for the slip velocity boundary condition has been analysed and validated. The influence of the Knudsen diffusion on the microreactor's performance has also been verified. It was revealed that with a given operating conditions and a given geometry of the microreactor, there is no need for application of slip boundary conditions and the Knudsen diffusion in further analysis. It has also been shown that the microreactor's length could be practically estimated using standard models.

On the modeling of thermohydrodynamic and biogeochemical processes in the inland water objects

2020 ◽  
Author(s):  
Daria Gladskikh ◽  
Evgeny Mortikov ◽  
Victor Stepanenko
Keyword(s):  
Carbon Dioxide ◽  
Numerical Study ◽  
Three Dimensional ◽  
Measurement Data ◽  
Dimensional Model ◽  
Three Dimensional Model ◽  
Inland Water ◽  
One Dimensional ◽  
Biochemical Processes ◽  
Dimensional Models

<p>Currently, one-dimensional and three-dimensional models are widely used to model thermohydrodynamic and biochemical processes in lakes and water rеreservoirs. One-dimensional models are highly computationally efficient and are used to parameterize land water bodies in climate models, however, when calculating large lakes and reservoirs with complex geometry, such models may incorrectly reproduce processes associated with horizontal heterogeneity. This becomes especially important for the prediction of water quality and euthrophication.</p><p>A three-dimensional model of thermohydrodynamics and biochemistry of an inland water obect is presented, which is based on the hydrostatic RANS model [1-3], and the parameterization of biochemical processes is implemented by analogy with the scheme for calculating biochemistry in the one-dimensional LAKE model [4]. Thus, the three-dimensional model is supplemented by a description of the transport of substances such as oxygen (O<sub>2</sub>), carbon dioxide (CO<sub>2</sub>), methane (CH<sub>4</sub>), as well as phyto- and zooplankton. The effect of turbulent diffusion and large-scale water movements on the distribution of a methane concentration field is studied.</p><p>To verify the calculation results, idealized numerical experiments and comparison with the measurement data on Lake Kuivajärvi (Finland) were used.</p><p>The work was supported by grants of the RF President’s Grant for Young Scientists (MK-1867.2020.5, MD-1850.2020.5) and by the RFBR (18-05-00292, 18-35-00602, 20-05-00776). <br><br>References:<br>[1] Mortikov E.V. Numerical simulation of the motion of an ice keel in stratified flow // Izv. Atmos. Ocean. Phys. 2016. 52. P. 108-115.<br>[2] Mortikov E.V., Glazunov A.V., Lykosov V.N. Numerical study of plane Couette flow: turbulence statistics and the structure of pressure-strain correlations // Russian Journal of Numerical Analysis and Mathematical Modelling. 2019. V. 34, N 2. P. 119-132.<br>[3] D.S. Gladskikh, V.M. Stepanenko, E.V. Mortikov, On the influence of the horizontal dimensions of inland waters on the thickness of the upper mixed layer. // Water Resourses. 2019. 18 pages. (submitted)<br>[4] Victor Stepanenko, Ivan Mammarella, Anne Ojala, Heli Miettinen, Vasily Lykosov, and Vesala Timo. LAKE 2.0: a model for temperature, methane, carbon dioxide and oxygen dynamics in lakes. Geoscientific Model Development, 9(5): 1977–2006, 2016.</p>

Numerical Simulation of a Mini-Channel Three-Way Catalytic Converter

2010 ◽  
Author(s):  
M. H. Akbari ◽  
R. Roohi ◽  
S. A. Asaee
Keyword(s):  
Conversion Efficiency ◽  
Single Channel ◽  
Heterogeneous Reaction ◽  
Catalytic Converter ◽  
Three Dimensional ◽  
Space Velocity ◽  
Kinetic Mechanism ◽  
Operating Conditions ◽  
Three Dimensional Model ◽  
Different Temperatures

A three-dimensional model is developed to simulate the behavior of a single-channel three-way catalytic converter. The flow regime is assumed to be steady and laminar, and the channel walls are considered as isothermal. A multi-step, global heterogeneous reaction mechanism with 16 reactions and 11 species is used in this investigation to enhance the accuracy of the results. The chemical reactions are assumed to occur only on the reactor walls. The developed model is validated against available experimental data for stoichiometric operating conditions. The effect of the feed temperature on the conversion efficiency of the main pollutant components is studied. The light-off temperature for the stoichiometric A/F is found to be about 530 K for CO, NO and UHC, and 425 K for H2 conversion. The model is also applied to predict the effect of reactor length and inlet mixture space velocity on the conversion efficiency at two different temperatures. By using the same kinetics a well-stirred, unsteady model is also developed to identify the sensitivity of the multi-step kinetic mechanism to the mixture composition. The effect of mole fraction variation of each species on the conversion of other mixture components is investigated.

scholarly journals Numerical study of dispersion and hydrodynamic connectivity of near-surface waters in Lake Huron

2012 ◽  
Vol 47 (3-4) ◽  
pp. 238-251 ◽  
Author(s):  
Jun Zhao ◽  
Yerubandi R. Rao ◽  
Jinyu Sheng
Keyword(s):  
Surface Waters ◽  
Numerical Study ◽  
Three Dimensional ◽  
Coastal Region ◽  
Lake Huron ◽  
Physical Parameters ◽  
Three Dimensional Model ◽  
Near Surface ◽  
Georgian Bay ◽  
Main Lake

A nested-grid hydrodynamic modeling system is used to examine the circulation and dispersion in Lake Huron and adjacent areas with specific attention to physical parameters pertinent to the estimation of hydrodynamic connectivity of near-surface waters. The nested system is forced by monthly mean surface heat flux and 12-hourly wind stress computed from wind speeds extracted from the National Centers for Environmental Prediction of the National Center for Atmospheric Research (NCEP/NCAR) 40-year reanalysis data. The three-dimensional model currents are used to calculate the retention and dispersion of conservative, near-surface particles carried by the currents. The near-surface dispersion is relatively low in Saginaw Bay, eastern Georgian Bay and the eastern North Channel; and relatively high over the western part of the main lake and the coastal region of south Lake Huron. The hydrodynamic connectivity in the surface water and connectivity matrices are calculated from particle movements carried passively by model currents superposed by a random walk process. The model results demonstrate that the hydrodynamic connectivity in the North Channel and Georgian Bay (ranging from 0.9 to 2.2%) is much weaker than those in the main lake (5.3 to 21.9%).

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