A Modelling Approach to the Design Optimization of Catalytic Converters of I.C. Engines

2003 ◽  
Author(s):  
Ming Chen ◽  
Karen Schirmer
Keyword(s):  
Design Optimization ◽  
Catalytic Converter ◽  
Plug Flow ◽  
Perforated Plate ◽  
Catalytic Converters ◽  
Screening Process ◽  
Perforated Plates ◽  
Semi Empirical ◽  
Modelling Approach ◽  
Catalyst Model

In this paper, a modelling approach to the design optimization of catalytic converters is presented. The first step of the optimization is the model-assisted sizing of catalysts. For a given inlet exhaust condition, a semi-empirical, experimentally calibrated, 0-D steady state catalyst model is employed to sort through a data base of catalysts under given restraints, yielding few successful candidates. Following this screening process, a 1-D transient plug-flow catalyst model is used to analyze the species concentrations and the temperature variation across the catalyst. The second step deals with the flow optimization of the catalyst converter under the given geometric restraints. A commercially available CFD package is employed to simulate isothermal flow and to evaluate flow uniformity characteristics in the catalytic converter. The substrate is modelled as porous media, where viscous and initial resistances are specified via empirical formula. With the help of the CFD tool, the flow in the converter can be optimized using appropriate boundary layer control methods. In a specific example, the effects of perforated plate on the flow separation in a wide-angle diffuser are demonstrated. This paper also addresses the issue of flow resistance of perforated plates.

Fluid Dynamic Aspects of Electrostatic Precipatators: Turbulence Characteristics in Scale Models

2003 ◽  
Vol 125 (4) ◽  
pp. 694-700 ◽  
Author(s):  
Aldo Coghe ◽  
Michele Mantegna ◽  
Giorgio Sotgia
Keyword(s):  
Fluid Dynamic ◽  
Perforated Plate ◽  
Hot Wire ◽  
Perforated Plates ◽  
Downstream Distance ◽  
Turbulence Decay ◽  
Scale Models ◽  
Electrostatic Precipitators ◽  
Semi Empirical ◽  
Good Agreement

The present work originated in an investigation on fluid dynamic aspects of electrostatic precipitators performed on scale models of an industrial apparatus. The experimental analysis of velocity and turbulence distribution, performed by hot-wire anemometry, confirmed that significant turbulence levels are found inside particle collectors. In fact, components used to spatially smooth the flow and lower its velocity peaks, such as hoods with wide divergence angles, turning vanes, and perforated plates, may also act as sources of turbulence and reduce the efficiency of electrostatic precipitators. These observations prompted a deeper analysis, both analytical and experimental, of the turbulence decay downstream perforated screens. A new simple semi-empirical model of turbulence decay is proposed, which has shown reasonably good agreement with experimental data, even at short downstream distance from the perforated plate, 50 to 250 hydraulic diameters.

High Speed Flow through Perforated Plates

1960 ◽  
Vol 64 (590) ◽  
pp. 103-105
Author(s):  
P. G. Morgan
Keyword(s):  
Pressure Drop ◽  
High Speed ◽  
Perforated Plate ◽  
Wire Mesh ◽  
Flow Conditions ◽  
High Speed Flow ◽  
Perforated Plates ◽  
Speed Flow ◽  
Flow Through ◽  
Points Of View

The flow through porous screens has been widely studied from both the theoretical and experimental points of view. The most widely used types of screen are the wire mesh and the perforated plate, and the majority of the literature has been concerned with the former. Several attempts have been made to correlate the parameters governing the flow through such screens, i.e. the pressure drop, the flow conditions and the geometry of the mesh.

scholarly journals THE STUDY OF ACOUSTIC CHARACTERISTICS OF THE PERFORATED AND HOMOGENOUS PLATES WITH SIMILAR GEOMETRICAL DIMENSIONS

Akustika ◽  
2019 ◽  
Vol 32 ◽  
pp. 79-82
Author(s):  
Valery Kirpichnikov ◽  
Lyudmila Drozdova ◽  
Alexei Koscheev ◽  
Ernst Myshinsky
Keyword(s):  
Resonant Frequency ◽  
Acoustic Radiation ◽  
Perforated Plate ◽  
Acoustic Characteristics ◽  
Resonant Frequencies ◽  
Perforated Plates ◽  
Resonance Frequencies ◽  
Flexural Vibrations ◽  
Geometrical Dimensions

The resonance frequencies of the flexural vibrations, input vibration excitability and acoustic radiation of the homogeneous and perforated plates were investigated. It is established that the average reduction range of the lower resonant frequency of flexural vibrations of the tested plates with the holes virtually coincides with the predictive estimate. The levels of the input vibration excitability of the perforated plate at the lower resonant frequencies exceeded the levels at the corresponding frequencies of the homogeneous plates greater than the calculated value. The levels of resonance acoustic radiation of the perforated plate were significantly less than of the homogeneous one.

The Aerodynamic Drag of Perforated Plates at Zero Incidence

1958 ◽  
Vol 62 (568) ◽  
pp. 301-303 ◽  
Author(s):  
P. Minton ◽  
J. R. D. Francis
Keyword(s):  
Pipe Flow ◽  
Aerodynamic Drag ◽  
Perforated Plate ◽  
Perforated Plates ◽  
Drag Forces ◽  
Flow Experiments

Perforated Plates have been used at large angles of incidence to produce drag forces and evidence on their properties has been published by de Bray. Less appears to be known about the drag forces on such surfaces at zero incidence, although they are usually considered to be aerodynamically rough. This has been confirmed by Ambrose, who carried out pipe flow experiments using perforated liners which fitted tightly in the bore of a pipe. Perforated plates used in this way do not allow flow completely through them and give “pitted” surfaces. If a perforated plate is mounted so that it is possible for cross flows to occur between the main flows on both sides of the plate the drag forces on it may be affected, and in this case the perforations will be referred to as “holes.”

Vibration Characteristics of a Perforated Plate Immersed in Fluid

2012 ◽  
Author(s):  
Tomohiro Ito ◽  
Atsuhiko Shintani ◽  
Chihiro Nakagawa
Keyword(s):  
Nuclear Power ◽  
Power Plants ◽  
Damping Ratio ◽  
Thermal Power ◽  
Perforated Plate ◽  
Vibration Characteristics ◽  
Chemical Plants ◽  
Perforated Plates ◽  
Stiffness Reduction ◽  
Test Models

Perforated plates are used in many mechanical structures in thermal power plants, nuclear power plants, or chemical plants etc. Cylindrical structures made by the perforated plates are also found in many places. However, vibration characteristics of the structures made by perforated plates are not fully clarified, especially for the structures immersed in liquid. The stiffness of the structures becomes smaller than that of ones made by simple plates with no holes, while the mass of the structures also becomes smaller. According to the balance between the stiffness reduction and mass reduction, natural frequencies will be decided. Moreover, added mass and added damping effects are very large in liquid, and are thought to largely change due to holes. In this study, as a fundamental step, a perforated plate is treated. The vibration characteristics such as natural frequency and damping ratio are studied for various hole numbers or various opening ratios by both numerical simulations and simple test models. Vibration tests are conducted in liquid as well as in air.

scholarly journals Recovery and Then Individual Separation of Platinum, Palladium, and Rhodium from Spent Car Catalytic Converters Using Hydrometallurgical Technique followed by Successive Precipitation Methods

2019 ◽  
Vol 2019 ◽  
pp. 1-7 ◽  
Author(s):  
Ahmed M. Yousif
Keyword(s):  
Contact Time ◽  
Catalytic Converter ◽  
Economic Value ◽  
Hydrogen Atmosphere ◽  
Catalytic Converters ◽  
Batch Experiments ◽  
Experimental Conditions ◽  
Leaching Process ◽  
Manufactured Products ◽  
Leaching Solution

Recovery of PGMs (especially rhodium, platinum, and palladium) from different spent manufactured products (like catalytic converters) is considered as an important task as they are rarely found in nature, and they possess high economic value. In this work, the honeycomb of a car catalytic converter was primarily processed by crushing, grinding, and then treating in a hydrogen atmosphere. In order to establish an economic and ecofriendly method for the recovery of studied PGMs, different experimental conditions of changing HCl/H2O2 (as a leaching solution) ratio, temperature, and contact time were studied through batch experiments to obtain the optimum leaching conditions. The use of 0.8 vol% H2O2 and 9.0 M HCl mixture at 60°C for a contact time of 2.5 hours during the leaching process may be considered as the best conditions to be followed to save chemicals, energy, and time (about 86%, 96%, and 98% of Rh, Pt, and Pd were recovered, respectively). Individual separation of PGM ions from each other using precipitation technique from their leaching liquor was performed where % purity values of 99.5, 99.3, and 95.5 were obtained for Pt, Pd, and Rh, respectively.

Interception of radionuclides by planophile crops: A simple semi-empirical modelling approach in case of nuclear accident fallout

2020 ◽  
Vol 266 ◽  
pp. 115308
Author(s):  
A. Cristina ◽  
R. Samson ◽  
N. Horemans ◽  
M. Van Hees ◽  
J. Wannijn ◽  
...  
Keyword(s):  
Nuclear Accident ◽  
Empirical Modelling ◽  
Semi Empirical ◽  
Modelling Approach

scholarly journals An Experimentally Validated Numerical Modeling Technique for Perforated Plate Heat Exchangers

2010 ◽  
Vol 132 (11) ◽  
Author(s):  
M. J. White ◽  
G. F. Nellis ◽  
S. A. Klein ◽  
W. Zhu ◽  
Y. Gianchandani
Keyword(s):  
Heat Transfer ◽  
Heat Exchanger ◽  
Numerical Model ◽  
Heat Exchangers ◽  
Perforated Plate ◽  
Plate Heat Exchanger ◽  
Internal Temperature ◽  
Perforated Plates ◽  
Axial Conduction ◽  
Plate Heat

Cryogenic and high-temperature systems often require compact heat exchangers with a high resistance to axial conduction in order to control the heat transfer induced by axial temperature differences. One attractive design for such applications is a perforated plate heat exchanger that utilizes high conductivity perforated plates to provide the stream-to-stream heat transfer and low conductivity spacers to prevent axial conduction between the perforated plates. This paper presents a numerical model of a perforated plate heat exchanger that accounts for axial conduction, external parasitic heat loads, variable fluid and material properties, and conduction to and from the ends of the heat exchanger. The numerical model is validated by experimentally testing several perforated plate heat exchangers that are fabricated using microelectromechanical systems based manufacturing methods. This type of heat exchanger was investigated for potential use in a cryosurgical probe. One of these heat exchangers included perforated plates with integrated platinum resistance thermometers. These plates provided in situ measurements of the internal temperature distribution in addition to the temperature, pressure, and flow rate measured at the inlet and exit ports of the device. The platinum wires were deposited between the fluid passages on the perforated plate and are used to measure the temperature at the interface between the wall material and the flowing fluid. The experimental testing demonstrates the ability of the numerical model to accurately predict both the overall performance and the internal temperature distribution of perforated plate heat exchangers over a range of geometry and operating conditions. The parameters that were varied include the axial length, temperature range, mass flow rate, and working fluid.

Local Heat/Mass Transfer Measurement on the Effusion Plate in Impingment/Effusion Cooling System

2000 ◽  
Author(s):  
Hyung Hee Cho ◽  
Dong Ho Rhee
Keyword(s):  
Mass Transfer ◽  
Heat Mass Transfer ◽  
Cooling System ◽  
Perforated Plate ◽  
Local Heat ◽  
Impinging Jets ◽  
Transfer Coefficients ◽  
Stagnation Region ◽  
Perforated Plates ◽  
Flow Acceleration

The present study is conducted to investigate the local heat/mass transfer characteristics for flow through perforated plates. A naphthalene sublimation method is employed to determine the local heat/mass transfer coefficients on the effusion plate. Two parallel perforated plates are arranged in two different configurations: staggered and shifted in one direction. The experiments are conducted for hole pitch-to-diameter ratios of 6.0, for gap distance between the perforated plates of 0.33 to 10 hole diameters, and for Reynolds numbers of 5,000 to 12,000. The result shows that the high transfer region is formed at stagnation region and at the mid-line of the adjacent impinging jets due to secondary vortices and flow acceleration to the effusion hole. For flows through the perforated plates, the mass transfer rates on the surface of the effusion plate are about six to ten times higher than for effusion cooling alone (single perforated plate). In general, higher heat/mass transfer is obtained with smaller gap distance between two perforated plates.

An Efficient Strategy for the Design Optimization of Combustor Exit Temperature Profile

2006 ◽  
Author(s):  
Oboetswe S. Motsamai ◽  
Jan A. Visser ◽  
Montressor Morris ◽  
Danie J. de Kock
Keyword(s):  
Design Optimization ◽  
Temperature Profile ◽  
Mathematical Optimization ◽  
Turbulent Diffusion Flame ◽  
Constrained Problems ◽  
Exit Temperature ◽  
Computational Fluid Dynamics Cfd ◽  
Semi Empirical ◽  
Mathematical Optimisation ◽  
Upstream Flow

A technique for design optimization of a combustor is presented in this study. The technique entails the use of Computational Fluid Dynamics (CFD) and mathematical optimization to minimize the combustor exit temperature profile. The empirical and semi-empirical correlations commonly used for optimizing Combustor Exit Temperature profile do not guarantee optimum. As experimental approach is time consuming and costly, use is made of numerical techniques. Using CFD without mathematical optimisation on a trial-and-error basis, however, does not guarantee optimal solutions. A better approach that is viewed as too expensive is a combination of the two approaches, thereby, incorporating the influence of the variables automatically. In this study the combustor exit temperature profile is optimised. The optimum (uniform) combustor exit temperature profile depends on mainly the geometric parameters. The combustor exit temperature profile is affected as soon as flow enters the combustor. However, in gas turbine applications where care has been taken on the influence of upstream flow related conditions, the combustor exit temperature profile is changed by dilution hole pattern and size. In this study dilution hole parameters have been used as optimization variables. The combustor in the study is an experimental liquid fuelled atmospheric combustor with turbulent diffusion flame. The CFD simulations uses the Fluent code with Standard k-ε model. The optimisation is carried out with Snyman’s Dynamic-Q algorithm, which is specifically designed to handle constrained problems where the objective or constraint functions are expensive to evaluate. The optimization leads to a more uniform combustor exit temperature profile as compared to the original.

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