Towards ECU-Executable Control-Oriented Models of a Three-Way Catalytic Converter

2015 ◽  
Author(s):  
Mario Santillo ◽  
Steve Magner ◽  
Mike Uhrich ◽  
Mrdjan Jankovic
Keyword(s):  
Catalytic Converter ◽  
Control Unit ◽  
Oxygen Storage ◽  
Exhaust Gas ◽  
Sensor Model ◽  
Vehicle Engine ◽  
Robust Model ◽  
Combined Models ◽  
Automated Optimization ◽  
Three Way Catalyst

The nonlinear dynamics of an automotive three-way catalyst (TWC) present a challenge to developing simple control-oriented models that are both useful for control and/or diagnostics and real-time executable within a vehicle engine-control unit (ECU). As such, we begin by developing a first-principles control-oriented TWC model and then proceed to apply simplifications. The TWC models are spatially discretized along the catalyst length to better understand and exploit the oxygen-storage dynamics. The TWC models also include the oxidation reaction of ceria by H2O, which is considered important since it represents the production of H2 within the catalyst. We present automated optimization routines to calibrate the TWC model along with a heated exhaust-gas oxygen (HEGO) sensor model using measured vehicle and emissions data. Finally, we demonstrate the combined models’ ability to accurately reproduce the measured HEGO voltage using engine feedgas constituent inputs, which is necessary for designing a robust model-based feedback controller.

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

2019 ◽  
Vol 9 (21) ◽  
pp. 4610 ◽  
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.

scholarly journals Control-oriented modelling of three-way catalytic converter for fuel-to-air ratio regulation in spark ignited engines

2019 ◽  
Vol 233 (14) ◽  
pp. 3758-3774
Author(s):  
Carlos Guardiola ◽  
Héctor Climent ◽  
Benjamín Pla ◽  
Marcelo Real
Keyword(s):  
Equivalence Ratio ◽  
Catalytic Converter ◽  
Model Performance ◽  
Oxygen Storage ◽  
Transient Dynamics ◽  
Gas Composition ◽  
Flow Temperature ◽  
Air Mass ◽  
The One ◽  
Three Way Catalyst

The purpose of this paper is to introduce a grey-box model of three-way catalytic converter, which is capable of estimating the oxygen storage level to aid the fuel-to-air ratio control in spark ignited engines. As it is well-known, the prime parameter that drives the transient dynamics in current three-way catalytic converter is their capability to store a certain amount of oxygen, then allowing to oxidize some pollutant species such as carbon monoxide or hydrocarbons even at rich conditions during short periods of time. Since oxygen storage level is considered a good indicator of the catalyst state but it cannot be directly measured, a model based real-time capable estimation like the one proposed in this paper could be valuable. The model accounts for oxygen storing as well as oxidation and reduction of the main species involved, taking as inputs fuel-to-air equivalence ratio, air mass flow, temperature and gas composition at three-way catalyst inlet. From these inputs, oxygen storage level and brick temperature are calculated as model states, which finally provide the gas composition downstream of the catalyst as output. In addition, a simplified model of narrowband [Formula: see text] sensor is included, it provides a voltage from gas composition at the outlet of the catalyst and allows to assess the model behaviour by comparison with the on-board [Formula: see text] sensor measurements. Finally, the validation of the model performance by means of experimental test as well as different practical cases, where the benefits of oxygen storage level estimation plays a key role, are introduced.

Nanostructured Cerium Oxide “Ecocatalysts”

MRS Bulletin ◽  
2001 ◽  
Vol 26 (11) ◽  
pp. 885-889 ◽  
Author(s):  
Maria Flytzani-Stephanopoulos
Keyword(s):  
Cerium Oxide ◽  
Catalytic Converter ◽  
Oxygen Storage Capacity ◽  
Industrial Applications ◽  
Oxygen Storage ◽  
Metal Catalyst ◽  
Fuel Ratio ◽  
Zirconium Oxides ◽  
Recent Compilation ◽  
Three Way Catalyst

Catalysts based on cerium oxide are now used as effective oxidation systems in numerous environmental applications. Cerium oxide was introduced into the catalysis field relatively recently, in 1976, and not as a catalyst initially. Rather, it was chosen as the key oxygen-storage component of the three-way catalyst (TWC) used in automotive exhausts. Accordingly, ceria is used to extend the air/fuel ratio window in the exhaust gas, releasing or accepting oxygen, respectively, under fuel-rich or fuellean conditions, so that the noble metal catalyst operates at the desirable stoichiometric air/fuel ratio, at which it effectively converts all three gaseous pollutants—CO, hydrocarbons, and NO—to innocuous products. A solid solution of cerium and zirconium oxides is used in today's catalytic converters because of its higher oxygen-storage capacity (OSC) compared with pure ceria. In the years that followed the introduction of ceria into the catalytic converter, many additional merits of cerium oxide were realized, first as an active catalytic component of the TWC and subsequently as a catalyst and sorbent in various industrial applications. A review article by Trovarelli on ceria-based catalysts is a good recent compilation.

Potential and Pitfalls in the Use of dual exhaust gas oxygen sensors for three-way catalyst monitoring and control

2003 ◽  
Vol 217 (6) ◽  
pp. 475-488 ◽  
Author(s):  
J C Peyton Jones ◽  
R A Jackson
Keyword(s):  
Catalyst Deactivation ◽  
Catalyst Activity ◽  
Oxygen Storage ◽  
Exhaust Gas ◽  
Strongly Correlated ◽  
Gas Composition ◽  
Monitoring And Control ◽  
Diagnostic Systems ◽  
And Control ◽  
Three Way Catalyst

Although it is known that exhaust gas oxygen (EGO) sensors are sensitive to gas composition, even at a constant air-fuel ratio (AFR), its significance in dual EGO sensor based catalyst control and on-board diagnostic systems has not been fully recognized. The (time varying) difference in gas composition across the catalyst gives rise to a dynamically changing bias component at the sensor output, which is not readily distinguishable from the oxygen storage and release effects the sensor is intended to monitor. Unless treated explicitly, this is likely to degrade the performance of dual EGO sensor based systems. However, the distortion itself also reflects catalyst activity and is strongly correlated with a reversible catalyst deactivation effect which dominates hydrocarbon and NO conversion efficiency under rich conditions. A method for exploiting the biased signal to obtain both improved estimates of the true AFR and an insight into the reversible deactivation effect is therefore outlined.

Calibration of the Oxygen Storage Reactions for the Modeling of an Automotive Three-Way Catalyst

2021 ◽  
Author(s):  
Augusto Della Torre ◽  
Gianluca Montenegro ◽  
Angelo Onorati ◽  
Stefano Paltrinieri ◽  
Federico Rulli ◽  
...  
Keyword(s):  
Oxygen Storage ◽  
Three Way Catalyst

Methodology to Evaluate the Fuel Economy of a Multimode Combustion Engine With Three-Way Catalytic Converter

2014 ◽  
Author(s):  
Sandro P. Nüesch ◽  
Anna G. Stefanopoulou ◽  
Li Jiang ◽  
Jeffrey Sterniak
Keyword(s):  
Fuel Economy ◽  
Combustion Engine ◽  
Catalytic Converter ◽  
Oxygen Storage ◽  
Nox Emissions ◽  
Combustion Mode ◽  
Mode Switch ◽  
Drive Cycle ◽  
Finite State ◽  
The Impact

Highly diluted, low temperature homogeneous charge compression ignition (HCCI) combustion leads to ultra-low levels of engine-out NOx emissions. A standard drive cycle, however, would require switches between HCCI and spark-ignited (SI) combustion modes. In this paper a methodology is introduced, investigating the fuel economy of such a multimode combustion concept in combination with a three-way catalytic converter (TWC). The TWC needs to exhibit unoccupied oxygen storage sites in order to show acceptable performance. But the lean exhaust gas during HCCI operation fills the oxygen storage and leads to a drop in NOx conversion efficiency. Eventually the levels of NOx become unacceptable and a mode switch to a fuel rich combustion mode is necessary in order to deplete the oxygen storage. The resulting lean-rich cycling leads to a penalty in fuel economy. In order to evaluate the impact of those penalties on fuel economy, a finite state model for combustion mode switches is combined with a longitudinal vehicle model and a phenomenological TWC model, focused on oxygen storage. The aftertreatment model is calibrated using combustion mode switch experiments from lean HCCI to rich spark-assisted HCCI and back. Fuel and emissions maps acquired in steady state experiments are used. Two depletion strategies are compared in terms of their influence on drive cycle fuel economy and NOx emissions.

Spatio-temporal dynamics of oxygen storage and release in a three-way catalytic converter

2014 ◽  
Vol 111 ◽  
pp. 180-190 ◽  
Author(s):  
Pankaj Kumar ◽  
Tian Gu ◽  
Karolos Grigoriadis ◽  
Matthew Franchek ◽  
Vemuri Balakotaiah
Keyword(s):  
Temporal Dynamics ◽  
Catalytic Converter ◽  
Oxygen Storage ◽  
Spatio Temporal

Estimation of Ethanol Content in Flex-Fuel Vehicles Using an Exhaust Gas Oxygen Sensor: Model, Tuning and Sensitivity

2008 ◽  
Author(s):  
Kyung-Ho Ahn ◽  
Anna G. Stefanopoulou ◽  
Mrdjan Jankovic
Keyword(s):  
Oxygen Sensor ◽  
Control Process ◽  
Engine Management System ◽  
Exhaust Gas ◽  
Fuel Blend ◽  
Analysis And Design ◽  
Sensor Model ◽  
Ethanol Content ◽  
Model Tuning ◽  
Adaptation Law

Throughout the history of the automobile there have been periods of intense interest in using ethanol as an alternative fuel to petroleum-based gasoline and diesel derivatives. Currently available flexible fuel vehicles (FFVs) can operate on a blend of gasoline and ethanol in any concentration of up to 85% ethanol. In all these FFVs, the engine management system relies on the estimation of the ethanol content in the fuel blend, which typically depends on the estimated changes in stoichiometry through an Exhaust Gas Oxygen (EGO) sensor. Since the output of the EGO sensor is used for the air-to-fuel ratio (AFR) regulation and the ethanol content estimation, several tuning and sensitivity problems arise. In this paper, we develop a simple phenomenological model of the AFR control process and a simple ethanol estimation law which can be representative of the currently practiced system in FFVs. Tuning difficulties and interactions of the two learning loops are then elucidated using classical control techniques. The sensitivity of the ethanol content estimation with respect to sensor and modeling errors is also demonstrated via simulations. The results point to an urgent need for model-based analysis and design of the AFR controller, the ethanol adaptation law and the fault detection issues in FFVs. Tuning and sensitivity issues are demonstrated via simulations and limitations are also discussed.

A low-dimensional model for describing the oxygen storage capacity and transient behavior of a three-way catalytic converter

2012 ◽  
Vol 73 ◽  
pp. 373-387 ◽  
Author(s):  
Pankaj Kumar ◽  
Imad Makki ◽  
James Kerns ◽  
Karolos Grigoriadis ◽  
Matthew Franchek ◽  
...  
Keyword(s):  
Storage Capacity ◽  
Catalytic Converter ◽  
Transient Behavior ◽  
Oxygen Storage Capacity ◽  
Oxygen Storage ◽  
Dimensional Model ◽  
Low Dimensional
Sign in / Sign up

Export Citation Format

Share Document