Dynamic Response of Automotive Catalytic Converters to Variations in Air-Fuel Ratio

2003 ◽  
Vol 125 (2) ◽  
pp. 547-554 ◽  
Author(s):  
T. Shamim ◽  
V. C. Medisetty
Keyword(s):  
Dynamic Response ◽  
Coupling Effect ◽  
Chemical Mechanism ◽  
Catalytic Converters ◽  
Engine Exhaust ◽  
Fuel Ratio ◽  
Flow Through ◽  
Automotive Catalytic Converters ◽  
Conversion Efficiencies ◽  
The Mathematical Model

The automotive catalytic converters, which are employed to reduce engine exhaust emissions, operate in transient conditions under all modes of operation. The fluctuation in air-fuel ratio is a major contributor to these transients. The consideration of these transients is essential in accurate modeling of catalyst operation during actual driving conditions. In this work, a numerical investigation is carried out to comprehend the dynamic response of three-way catalytic converters subjected to changes in air-fuel ratio. The mathematical model considers the coupling effect of heat and mass transfer with the catalyst reactions as exhaust gases flow through the catalyst. The converter dynamic response is studied by considering a converter operating under steady conditions, which is suddenly subjected to air-fuel ratio variations. Two types of imposed fluctuations (sinusoidal and step changes) are considered. The catalyst response is predicted by using a detailed chemical mechanism. The paper elucidates the effect of air-fuel modulations on the catalyst HC, CO, and NO conversion efficiencies.

Dynamic Response of Automotive Catalytic Converters to Variations in Air-Fuel Ratio

2001 ◽  
Author(s):  
Tariq Shamim ◽  
Vishnu C. Medisetty
Keyword(s):  
Dynamic Response ◽  
Coupling Effect ◽  
Chemical Mechanism ◽  
Catalytic Converters ◽  
Engine Exhaust ◽  
Fuel Ratio ◽  
Flow Through ◽  
Automotive Catalytic Converters ◽  
Conversion Efficiencies ◽  
The Mathematical Model

Abstract The automotive catalytic converters, which are employed to reduce engine exhaust emissions, operate in transient conditions under all modes of operation. The fluctuation in air-fuel ratio is a major contributor to these transients. The consideration of these transients is essential in accurate modeling of catalyst operation during actual driving conditions. In this work, a numerical investigation is carried out to comprehend the dynamic response of three-way catalytic converters subjected to changes in air-fuel ratio. The mathematical model considers the coupling effect of heat and mass transfer with the catalyst reactions as exhaust gases flow through the catalyst. The converter dynamic response is studied by considering a converter operating under steady conditions, which is suddenly subjected to air-fuel ratio variations. Two types of imposed fluctuations (sinusoidal and step changes) are considered. The catalyst response is predicted by using a detailed chemical mechanism. The paper elucidates the effect of air-fuel modulations on the catalyst HC, CO, and NO conversion efficiencies.

Dynamic Response of Spiral Cantilever Undergoing Magnetic Coupling

2014 ◽  
Vol 14 (08) ◽  
pp. 1440021
Author(s):  
Xiaoling Bai ◽  
Yumei Wen ◽  
Ping Li ◽  
Jin Yang ◽  
Xiao Peng ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Cantilever Beam ◽  
Magnetic Force ◽  
Coupling Effect ◽  
Magnetic Coupling ◽  
Resonant Frequencies ◽  
Energy Harvesters ◽  
Magnetic Transducer ◽  
Underlying Mechanisms ◽  
Tip Mass

Cantilever beams have found intensive and extensive uses as underlying mechanisms for energy transduction in sensors as well as in energy harvesters. In magnetoelectric (ME) transduction, the underlying cantilever beam usually will undergo magnetic coupling effect. As the beam itself is either banded with magnetic transducer or magnets, the dynamic motion of the cantilever can be modified due to the magnetic force between the magnets and ME sensors. In this study, the dynamic response of a typical spiral cantilever beam with magnetic coupling is investigated. The spiral cantilever acts as the resonator of an energy harvester with a tip mass in the form of magnets, and a ME transducer is positioned in the air gap and interacts with the magnets. It is expected that this spiral configuration is capable of performing multiple vibration modes over a small frequency range and the response frequencies can be magnetically tunable. The experimental results show that the magnetic coupling between the magnets and the transducer plays a favorable role in achieving tunable resonant frequencies and reducing the frequency spacings. This will benefits the expansion of the response band of a device and is especially useful in energy harvesting.

The Effect of Engine Exhaust Temperature Modulations on the Performance of Automotive Catalytic Converters

2006 ◽  
Author(s):  
Tariq Shamim
Keyword(s):  
Single Channel ◽  
Catalytic Converter ◽  
Space Velocity ◽  
Operating Conditions ◽  
Gas Temperature ◽  
Engine Exhaust ◽  
Exhaust Temperature ◽  
Automotive Catalytic Converters ◽  
Exhaust Gas Temperature ◽  
Harmful Effects

This paper presents a computational investigation of the effect of exhaust temperature modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converter’s performance under transient driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies. The study employs a single-channel based, one-dimensional, non-adiabatic model. The transient conditions are imposed by varying the exhaust gas temperature sinusoidally. The results show that temperature modulations cause a significant departure in the catalyst behavior from its steady behavior, and modulations have both favorable and harmful effects on pollutant conversion. The operating conditions and the modulating gas composition and flow rates (space velocity) have substantial influence on catalyst behavior.

scholarly journals Study on the Stability of the Geogrids-Reinforced Earth Slope under the Coupling Effect of Rainfall and Earthquake

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Xijun Zhang ◽  
Liang Huang ◽  
Yujie Hou ◽  
Bo Wang ◽  
Binghan Xue ◽  
...  
Keyword(s):  
Dynamic Response ◽  
Coupling Effect ◽  
Calculation Model ◽  
Influential Factor ◽  
Construction Design ◽  
Reinforced Earth ◽  
Overall Stability ◽  
Earth Slope ◽  
Earth Slopes ◽  
The Stability

This paper focuses on understanding the dynamic response problem of flexible wrapped reinforced Earth slope under the coupling effect of earthquake and rainfall; a numerical calculation model of reinforced Earth slope considering the coupling effect of earthquake and rainfall was established. The dynamic response, pore pressure, and tensile stress distribution of the reinforcement under the rainfall before earthquake, the rainfall after the earthquake, and earthquake-rainfall are studied. The results show that the coupling effect of earthquake and rainfall is an influential factor in the dynamic analysis of reinforced Earth slopes, the analysis of which should be paid attention to and researched in the future. The combination of geogrid and soil effectively improves the deformation of the slope and the overall stability, reduces the secondary disaster of the slope, and provides a reference for the seismic construction design of the reinforced Earth slope.

scholarly journals Framing the MHD Micropolar-Nanofluid Flow in Natural Convection Heat Transfer over a Radiative Truncated Cone

Processes ◽  
2020 ◽  
Vol 8 (4) ◽  
pp. 379 ◽  
Author(s):  
Waqar A. Khan ◽  
A.M. Rashad ◽  
S.M.M. EL-Kabeir ◽  
A.M.A. EL-Hakiem
Keyword(s):  
Mathematical Model ◽  
Base Fluid ◽  
Transmission Rate ◽  
Convection Heat Transfer ◽  
Heat Transmission ◽  
Nanofluid Flow ◽  
Micropolar Nanofluid ◽  
Flow Through ◽  
The Mathematical Model ◽  
Linear Radiation

Recently, nanoparticles have supplied diverse challenges in the area of science. The nanoparticles suspended in several conventional fluids can convert the fluids flow and heat transmission features. In this investigation, the mathematical approach is utilized to explore the magnetohydrodynamics micropolar-nanofluid flow through a truncated porous cone. In this mathematical model, non-linear radiation and suction/injection phenomena are also scrutinized with the Tiwari-Das nanoliquid pattern. The designed system of the mathematical model of the boundary value problem is converted to a set of dimensionless non-similar equations applying convenient transformations. In this study, kerosene oil is selected as the base fluid, while the nanoparticles of Fe3O4 are utilized to promote the heat transmission rate. The problem is solved numerically using the Runge-Kutta-Fehlberg method (RKF45). It is demonstrated that an enhancement in the pertinent parameters improves the heat transmission rate.

Automotive catalytic converters: current status and some perspectives

2003 ◽  
Vol 77 (4) ◽  
pp. 419-449 ◽  
Author(s):  
Jan Kašpar ◽  
Paolo Fornasiero ◽  
Neal Hickey
Keyword(s):  
Current Status ◽  
Catalytic Converters ◽  
Automotive Catalytic Converters

scholarly journals Improper management of dams constructed with local materials, infiltration risk and wasted electric energy

2018 ◽  
Vol 178 ◽  
pp. 09009
Author(s):  
Victorita Radulescu
Keyword(s):  
Cross Sections ◽  
Electric Energy ◽  
Water Volume ◽  
Hydropower Plants ◽  
Flow Through ◽  
Different Dimensions ◽  
Study Case ◽  
The Mathematical Model ◽  
Local Materials ◽  
Reduced Water

The present paper presents a study case of improper dike rehabilitation and inefficient management of the water volume from two hydropower lakes, with dams built with local materials. In Romania, with its high hydrographic potential, this solution was adopted for construction of more than 600 hydropower plants, many of them now confronted with infiltration and erosion, and appeared into lateral sides of the dikes. The paper covers some theoretical and practical aspects referring to the functioning of hydropower lakes, establishing the cross-sections with problems in exploitation. Reduced water level produces less electric energy than initially estimated. The dam's construction was not correlated with the geomorphologic conditions and climatic parameters, being necessary supplementary measurements and data acquisition to calibrate the numerical model. There are mentioned some considerations referring at the mathematical model, based on new hypotheses of infiltration through sediments with different dimensions and characteristics. The flow through dikes is assumed non-permanent due to massive infiltration. Part of the numerical modeling, the obtained velocities of infiltration, and the streamlines are illustrated. The results of the tested solution prove its efficiency and allow illustrating and some other sections with possible risk in functioning. Some discussions, conclusions, and references are finally presented.

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