Dynamic behaviour of automotive catalytic converters subjected to variations in engine exhaust compositions

2005 ◽  
Vol 6 (6) ◽  
pp. 557-567 ◽  
Author(s):  
T Shamim
Keyword(s):  
Dynamic Behaviour ◽  
Single Channel ◽  
Catalytic Converter ◽  
Computational Investigation ◽  
Engine Exhaust ◽  
One Dimensional ◽  
Transient Behaviour ◽  
Fundamental Understanding ◽  
Automotive Catalytic Converters ◽  
Harmful Effects

This paper presents a computational investigation of the effect of composition modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converte's performance under actual driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies by exploiting the catalyst transient behaviour. The study employs a single-channel-based, one-dimensional, non-adiabatic model. Two types of imposed transients (sinusoidal and step changes) are considered. The results show that composition modulations cause a significant departure in the catalyst behaviour from its steady behaviour, and modulations have both favourable and harmful effects on pollutant conversion.

Dynamic Response of Automotive Catalytic Converters to Modulations in Engine Exhaust Compositions

2003 ◽  
Author(s):  
Tariq Shamim
Keyword(s):  
Single Channel ◽  
Catalytic Converter ◽  
Transient Behavior ◽  
Operating Conditions ◽  
Engine Exhaust ◽  
Co Conversion ◽  
Fundamental Understanding ◽  
Conversion Performance ◽  
Automotive Catalytic Converters ◽  
Harmful Effects

This paper presents a computational investigation of the effect of composition modulations on an automotive catalytic converter. The objective is to develop a better fundamental understanding of the converter’s performance under actual driving conditions. Such an understanding will be beneficial in devising improved emission control methodologies by exploiting the catalyst transient behavior. The study employs a single-channel based, one-dimensional, non-adiabatic model. Two types of imposed transients (sinusoidal and step changes) are considered. The results show that composition 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 departure is relatively significant for catalyst CO and HC conversion performance. The operating conditions and the modulating gas composition have substantial influence on catalyst behavior. Near stoichiometric condition, modulations of HC concentration have relatively greater effect and result in increased CO and HC conversions. Modulations of CO, on the other hand, result in a decrease of CO conversion. The effect of CO modulations on HC conversion is slightly positive. For the conditions studied, NO modulations generally do not result in any significant change in catalyst performance.

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.

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

2007 ◽  
Vol 130 (1) ◽  
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, nonadiabatic 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.

An Investigation on the Performance of an Oxidation Catalyst Using Two-dimensional Simulation with Detailed Reaction Mechanism

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Sreeharsh Nair ◽  
Mayank Mittal
Keyword(s):  
Single Channel ◽  
Catalytic Converter ◽  
Oxidation Catalyst ◽  
Low Temperature Combustion ◽  
Wide Range ◽  
Detailed Reaction Mechanism ◽  
Temperature Combustion ◽  
High Concentrations ◽  
Dimensional Simulation ◽  
Surface Reaction Kinetics

AbstractThe advent of stricter emission standards has increased the importance of aftertreatment devices and the role of numerical simulations in the evolution of better catalytic converters in order to satisfy these emission regulations. In this paper, a 2-D numerical simulation of a single channel of the monolith catalytic converter is presented by using detailed surface reaction kinetics aiming to investigate the chemical behaviour inside the converter. The model has been developed to study the conversion of carbon monoxide (CO) in the presence of propene (C3H6) for low-temperature combustion (LTC) engine application. The inhibition effect of C3H6 over a wide range of CO inlet concentrations is investigated. Considering both low and high levels of CO concentration at the inlet, the 2-D model predicted better results than their corresponding 1-D counterparts when compared with the experimental data from literature. It was also observed that C3H6 inhibition at high temperatures was significant, particularly for high concentrations of CO compared to low concentrations of CO at the inlet.

scholarly journals Slow light bimodal interferometry in one-dimensional photonic crystal waveguides

2021 ◽  
Vol 10 (1) ◽  
Author(s):  
Luis Torrijos-Morán ◽  
Amadeu Griol ◽  
Jaime García-Rupérez
Keyword(s):  
Photonic Crystal ◽  
Group Velocity ◽  
Communication Networks ◽  
Slow Light ◽  
Single Channel ◽  
Point Of Care ◽  
Semiconductor Industry ◽  
Optical Modulator ◽  
One Dimensional ◽  
Dimensional Photonic Crystal

AbstractStrongly influenced by the advances in the semiconductor industry, the miniaturization and integration of optical circuits into smaller devices has stimulated considerable research efforts in recent decades. Among other structures, integrated interferometers play a prominent role in the development of photonic devices for on-chip applications ranging from optical communication networks to point-of-care analysis instruments. However, it has been a long-standing challenge to design extremely short interferometer schemes, as long interaction lengths are typically required for a complete modulation transition. Several approaches, including novel materials or sophisticated configurations, have been proposed to overcome some of these size limitations but at the expense of increasing fabrication complexity and cost. Here, we demonstrate for the first time slow light bimodal interferometric behaviour in an integrated single-channel one-dimensional photonic crystal. The proposed structure supports two electromagnetic modes of the same polarization that exhibit a large group velocity difference. Specifically, an over 20-fold reduction in the higher-order-mode group velocity is experimentally shown on a straightforward all-dielectric bimodal structure, leading to a remarkable optical path reduction compared to other conventional interferometers. Moreover, we experimentally demonstrate the significant performance improvement provided by the proposed bimodal photonic crystal interferometer in the creation of an ultra-compact optical modulator and a highly sensitive photonic sensor.

Numerical exploration on snap buckling of a pre-stressed hemispherical gridshell

2021 ◽  
pp. 1-11
Author(s):  
Weicheng Huang ◽  
Longhui Qin ◽  
Qiang Chen
Keyword(s):  
Three Dimensional ◽  
Energy Functional ◽  
Elastic Rods ◽  
Geometrically Nonlinear ◽  
Local Response ◽  
Micro Electro Mechanical Systems ◽  
One Dimensional ◽  
Numerical Exploration ◽  
Planar Grid ◽  
Fundamental Understanding

Abstract Motivated by the observations of snap-through phenomena in pre-stressed strips and curved shells, we numerically investigate the snapping of a pre-buckled hemispherical gridshell under apex load indentation. Our experimentally validated numerical framework on elastic gridshell simulation combines two components: (i) Discrete Elastic Rods method, for the geometrically nonlinear description of one dimensional rods; and (ii) a naive penalty-based energy functional, to perform the non-deviation condition between two rods at joint. An initially planar grid of slender rods can be actuated into a three dimensional hemispherical shape by loading its extremities through a prescribed path, known as buckling induced assembly; next, this pre-buckled structure can suddenly change its bending direction at some threshold points when compressing its apex to the other side. We find that the hemispherical gridshell can undergo snap-through buckling through two different paths based on two different apex loading conditions. The first critical snap-through point slightly increases as the number of rods in gridshell structure becomes denser, which emphasizes the mechanically nonlocal property in hollow grids, in contrast to the local response of continuum shells. The findings may bridge the gap among rods, grids, knits, and shells, for a fundamental understanding of a group of thin elastic structures, and inspire the design of novel micro-electro-mechanical systems and functional metamaterials.

Theoretical and computational investigation of the electrochemical machining process for characteristic cases of a stepped moving tool eroding a plane surface

1997 ◽  
Vol 211 (3) ◽  
pp. 197-210 ◽  
Author(s):  
H Hardisty ◽  
A R Mileham ◽  
H Shirvani
Keyword(s):  
Plane Surface ◽  
Electrochemical Machining ◽  
Machining Process ◽  
Surface Erosion ◽  
Computational Investigation ◽  
Step Size ◽  
One Dimensional ◽  
Erosion Rates ◽  
Spatial Differences ◽  
The One

A theoretical and computational investigation into the electrochemical machining (ECM) process for the case of a moving stepped tool eroding an initially flat surface is presented. Five parametric variations of the basic geometry of the stepped tool machining process are possible, depending on the relative distance between the moving tool and eroded work. For each of the five cases, and based on one-dimensional theory, formulae have been developed to predict the minimum depth of working material that must initially be provided to enable a particular step size to be machined to a specified tolerance. The computer simulation of the ECM process which has been developed is based on the finite element method (FEM). The geometry of tool, electrolyte and work is simulated by means of a two-dimensional mesh of square elements. A system of macros has been developed which interact internally with an FE package to move component boundaries systematically to simulate both tool movement and surface erosion. Such boundary movements are accomplished automatically and continuously without user intervention during a simulation run. The algorithms employed to achieve characteristically different erosion rates are described. Results both from one-dimensional ECM theory and from the computer simulations of the characteristic cases are presented. Comparisons show that there is good agreement between computer predictions and theory. The differential erosion process is fundamental to all ECM processes. Complex shapes evolve because of spatial differences in erosion rates. Thus the one-dimensional results presented here for the formation of a step should provide a basis for comparisons between spatially separated regions of one-dimensional differential erosion on bodies of arbitrary shape.

Numerical Simulation of Thermal and Fluid-Dynamic Behaviour of Reciprocating Compressor

2000 ◽  
Author(s):  
Zhilong He ◽  
Xueyuan Peng ◽  
Pengcheng Shu
Keyword(s):  
Numerical Simulation ◽  
Fluid Flow ◽  
Heat Balance ◽  
Dynamic Behaviour ◽  
Fluid Dynamic ◽  
Reciprocating Compressor ◽  
One Dimensional ◽  
Compressor Design ◽  
Suction Line ◽  
Hermetic Compressor

Abstract This paper presents a numerical method for simulating the thermal and fluid-dynamic behavior of hermetic compressors in the whole compressor domain. The model of fluid flow is developed by integrating transient one-dimensional conservation equations of continuity, momentum and energy through all of the elements from suction line to discharge line. The model describing thermal behavior is based on heat balance in the components such as muffler, connecting tubes and orifices. The calculation of the thermodynamic and transport properties for different refrigerants at various conditions has been considered, and some numerical results for a hermetic compressor are presented. The present study has demonstrated that the numerical simulation is a fest and reliable tool for compressor design.

Hexaphosphaferrocene [Fe(η5-P3C2tBu2)2] as a Connecting Moiety in Oligomeric and Polymeric Compounds

2009 ◽  
Vol 64 (11-12) ◽  
pp. 1429-1437 ◽  
Author(s):  
Andrea Schindler ◽  
Manfred Zabel ◽  
John F. Nixon ◽  
Manfred Scheer
Keyword(s):  
Dynamic Behaviour ◽  
Stoichiometric Ratio ◽  
Ladder Structure ◽  
Polymeric Compound ◽  
One Dimensional ◽  
Polymeric Compounds

The hexaphosphaferrocene complex [Fe(η5-P3C2tBu2)2] (1) derived from the corresponding 1,2,4-triphosphospholyl anion reacts with CuX (X = Cl, Br, I) in a 1 : 1 stoichiometry to give the isostructural, one-dimensional polymeric compounds [{Cu(μ3-X)}4{Fe(μ,η5:η1-P3C2tBu2)2}2]n (X = Cl (2), Br (3), I (4)), which display a unique sinusoidal (CuX)n ladder structure. In the reaction with CuI a second one-dimensional polymeric compound [{Cu3(μ-I)(μ3-I)2}(CH3CN){Fe(μ,η5:η1- P3C2tBu2)(μ3,η5:η1-P3C2tBu2)}]n (5) is formed. The reaction of 1 with CuX (X= Cl, Br, I) in a 1 : 2 stoichiometric ratio leads only in the case of CuCl to the formation of the new, oligomeric compound [{Cu(μ3-Cl)}4(CH3CN)2{Fe(μ,η5:η1-P3C2tBu2)2}2] (6), whereas in the case of CuBr and CuI the polymeric compounds 3 and 5 were isolated. The reaction of 1 with Ag[Al{OC(CF3)3}4] in a 1:1 stoichiometric ratio results in the formation of [Ag{Fe(μ,η5:η1-P3C2tBu2)2}2][Al{OC(CF3)3}4] (7), which shows dynamic behaviour in solution

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