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

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.

ASME 2006 Internal Combustion Engine Division Spring Technical Conference (ICES2006) ◽

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

10.1115/ices2006-1413 ◽

2006 ◽

Author(s):

Tariq Shamim

Keyword(s):

Single Channel ◽

Catalytic Converter ◽

Space Velocity ◽

Operating Conditions ◽

Gas Temperature ◽

Engine Exhaust ◽

Exhaust Temperature ◽

Exhaust Gas Temperature ◽

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

Journal of Engineering for Gas Turbines and Power ◽

10.1115/1.2747256 ◽

2007 ◽

Vol 130 (1) ◽

Cited By ~ 3

Author(s):

Tariq Shamim

Keyword(s):

Single Channel ◽

Catalytic Converter ◽

Space Velocity ◽

Operating Conditions ◽

Gas Temperature ◽

Engine Exhaust ◽

Exhaust Temperature ◽

Exhaust Gas Temperature ◽

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.

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

International Journal of Engine Research ◽

10.1243/146808705x27705 ◽

2005 ◽

Vol 6 (6) ◽

pp. 557-567 ◽

Cited By ~ 7

Author(s):

T Shamim

Keyword(s):

Dynamic Behaviour ◽

Single Channel ◽

Catalytic Converter ◽

Computational Investigation ◽

Engine Exhaust ◽

One Dimensional ◽

Transient Behaviour ◽

Fundamental Understanding ◽

Modeling of Three-Way Catalyst Dynamics for a Compressed Natural Gas Engine during Lean–Rich Transitions

Applied Sciences ◽

10.3390/app9214610 ◽

2019 ◽

Vol 9 (21) ◽

pp. 4610 ◽

Cited By ~ 3

Author(s):

Dario Di Maio ◽

Carlo Beatrice ◽

Valentina Fraioli ◽

Pierpaolo Napolitano ◽

Stefano Golini ◽

...

Keyword(s):

Steady State ◽

Natural Gas ◽

Catalytic Converter ◽

Operating Conditions ◽

Oxygen Storage ◽

Continuous Control ◽

Engine Exhaust ◽

Compressed Natural Gas ◽

The Impact ◽

Three Way Catalyst

The main objective of the present research activity was to investigate the effect of very fast composition transitions of the engine exhaust typical in real-world driving operating conditions, as fuel cutoff phases or engine misfire, on the aftertreatment devices, which are generally very sensitive to these changes. This phenomenon is particularly evident when dealing with engines powered by natural gas, which requires the use of a three-way catalyst (TWC). Indeed, some deviations from the stoichiometric lambda value can interfere with the catalytic converter efficiency. In this work, a numerical “quasi-steady” model was developed to simulate the chemical and transport phenomena of a specific TWC for a compressed natural gas (CNG) heavy-duty engine. A dedicated experimental campaign was performed in order to evaluate the catalyst response to a defined λ variation pattern of the engine exhaust stream, thus providing the data necessary for the numerical model validation. Tests were carried out to reproduce oxygen storage phenomena that make catalyst behavior different from the classic steady-state operating conditions. A surface reaction kinetic mechanism concerning CH4, CO, H2, oxidation and NO reduction has been appropriately calibrated at different λ values with a step-by-step procedure, both in steady-state conditions of the engine work plan and during transient conditions, through cyclical and consecutive transitions of variable frequency between rich and lean phases. The activity also includes a proper calibration of the reactions involving cerium inside the catalyst in order to reproduce oxygen storage and release dynamics. Sensitivity analysis and continuous control of the reaction rate allowed evaluating the impact of each of them on the exhaust composition in several operating conditions. The proposed model predicts tailpipe conversion/formation of the main chemical species, starting from experimental engine-out data, and provides a useful tool to evaluate the catalyst’s performance.

ASME 2010 8th International Conference on Nanochannels, Microchannels, and Minichannels: Parts A and B ◽

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

10.1115/fedsm-icnmm2010-30239 ◽

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.

ASME 2005 Internal Combustion Engine Division Fall Technical Conference (ICEF2005) ◽

Simulation of an Automotive Catalytic Converter Internal Flow

10.1115/icef2005-1339 ◽

2005 ◽

Author(s):

Bassem H. Ramadan

Keyword(s):

Oxygen Sensor ◽

Catalytic Converter ◽

Internal Flow ◽

The United States ◽

Operating Conditions ◽

Current Status ◽

Reacting Flow ◽

Exhaust Manifold ◽

Catalytic Converters ◽

Engine Exhaust

Catalytic converters have been used for a number of years in the United States to control automotive pollution. A catalytic converter needs to reach a certain temperature before the chemical reactions take place (light-off). Recently, the new regulations on emission standards have prompted a reconsideration of the design of automotive catalytic converters in order to reduce the light-off period of the catalyst. The catalytic converter light-off period is very Important since almost 80% of the emissions from vehicles occur within the first three minutes after cold start in the FTP-75 test. In order to meet these new regulations, current studies have suggested that the catalyst should be “close-coupled”; that is fitted close to the engine exhaust manifold. In order to design “close-coupled” converters, the designer may have to resort to truncated inlet and outlet cones, or distorted inlet pipes due to space limitations. Hence, it is very difficult to achieve good mixing of the exhaust gas, and a good flow distribution at the inlet cross section of the monolith. Based on such a current status in the study of the catalytic converter, the present work focuses on the time-dependent flow patterns, both in the exhaust manifold and the catalytic converter using Computational Fluid Dynamics (CFD). A three-dimensional grid model of an engine exhaust manifold and a close-coupled catalytic converter was developed and analyzed. The flow simulations were performed using KIVA-3 for non-reacting flow fields. These simulations were performed with transient boundary conditions applied at the inlet to the exhaust runners to simulate the opening and closing of exhaust valves. The CFD results were used to study flow uniformity under different operating conditions and to identify the best location for the oxygen sensor.

A Three-Dimensional Transient Numerical Study of a Close-Coupled Catalytic Converter Internal Flow

Volume 2, Parts A and B ◽

10.1115/ht-fed2004-56545 ◽

2004 ◽

Author(s):

Bassem H. Ramadan

Keyword(s):

Oxygen Sensor ◽

Numerical Study ◽

Catalytic Converter ◽

Three Dimensional ◽

Internal Flow ◽

Operating Conditions ◽

Current Status ◽

Reacting Flow ◽

Exhaust Manifold ◽

Engine Exhaust

Recently, the new regulations on emission standards have prompted a reconsideration of the design of automotive catalytic converters in order to reduce the light-off period of the catalyst. The catalytic converter light-off period is very Important since almost 80% of the emissions from vehicles occur within the first three minutes after cold start in the FTP-75 test. In order to meet these new regulations, current studies have suggested that the catalyst should be “close-coupled”; that is fitted close to the engine exhaust manifold. In order to design “close-coupled” converters, the designer may have to resort to truncated inlet and outlet cones, or distorted inlet pipes due to space limitations. Hence, it is very difficult to achieve good mixing of the exhaust gas, and a good flow distribution at the inlet cross section of the monolith. Based on such a current status in the study of the catalytic converter, the present work focuses on the time-dependent flow patterns, both in the exhaust manifold and the catalytic converter using Computational Fluid Dynamics (CFD). A three-dimensional grid model of an engine exhaust manifold and a close-coupled catalytic converter was developed and analyzed. The flow simulations were performed using KIVA-3 for non-reacting flow fields. These simulations were performed with transient boundary conditions applied at the inlet to the exhaust runners to simulate the opening and closing of exhaust valves. The CFD results were used to study flow uniformity under different operating conditions and to identify the best location of the oxygen sensor.

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

Chemical Product and Process Modeling ◽

10.1515/cppm-2019-0115 ◽

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.

ASME 2013 11th International Conference on Fuel Cell Science, Engineering and Technology ◽

Transient Response of Polymer Electrolyte Membrane Fuel Cell to Variations in Operating Parameters

10.1115/fuelcell2013-18210 ◽

2013 ◽

Author(s):

A. Verma ◽

R. Pitchumani

Keyword(s):

Fuel Cell ◽

Transient Response ◽

Single Channel ◽

Rapid Change ◽

Transient Behavior ◽

Pem Fuel Cells ◽

Proton Exchange ◽

Operating Parameters ◽

Complex Species ◽

Cyclic Changes

Due to rapid change in loads during automotive applications, study of dynamic behavior of proton exchange membrane (PEM) fuel cells is of paramount importance for their successful deployment in mobile applications. Toward understanding the effects of changes in operating parameters on the transient behavior, this paper presents numerical simulations for a single channel PEM fuel cell undergoing cyclic changes in operating parameters. The objective is to elucidate the complex interaction between power response and complex species (water, hydrogen and oxygen) transport dynamics for applied cyclic changes. This study focuses on studying the transient response of fuel cell for specified changes in operating parameters — voltage, pressure and stoichiometry at the cathode and the anode. Numerical studies are carried out on single-channel PEMFC’s to illustrate the response of power as the operating parameters are subjected to specified changes. The operating parameters are further optimized using a one dimensional physics based model with an objective to match the power requirements of a drive cycle over a defined period of time.