Computer aided assessment and optimization of catalyst fast light-off techniques

Konstantinidis, P.G.; Koltsakis, G. C.; Stamatelos, A. M.

doi:10.1243/0954407971526191

Cited by 15 publications

(3 citation statements)

References 17 publications

(25 reference statements)

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“…The output of the model is the respective second-bysecond variation in exhaust gas composition and temperature at the catalyst exit, as well as the catalyst bed temperatures [9]. In its present state, the model does not account for particulate matter oxidation in the catalyst.…”

Section: Application Of the Catalytic Converter Modelmentioning

confidence: 99%

Statistical uncertainty in automotive emissions testing

Kandylas

Stamatelos

Dimitriadis

1999

Proceedings of the Institution of Mechanical Engineers, Part D:

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Automotive exhaust emission testing according to legislated procedures and driving cycles is a routine process today in the United States, Europe and SE Asia. In practice, the selection of catalytic converters and the general design of exhaust aftertreatment systems are mainly aimed at the attainment of the legislated emissions limits with a reasonable safety margin. However, during the system optimization process, the catalyst and/or exhaust system manufacturer screens a large number of catalysts with a significant number of system design variations. In this process, certain levels of statistical uncertainty are present and must be seriously taken into account as stricter emissions standards are addressed and the safety margins become leaner. A methodology is developed and presented in this paper that is able to determine confidence levels in the attainment of specific emissions limits. This methodology combines results from experimental assessment of the distributions of engine-out emissions and catalyst activity by employing a previously developed and extensively validated model of a diesel oxidation catalyst. In this way, the emissions control system optimization is substantially aided and the required experimental effort is considerably reduced.

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Section: Application Of the Catalytic Converter Modelmentioning

confidence: 99%

Statistical uncertainty in automotive emissions testing

Kandylas

Stamatelos

Dimitriadis

1999

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…Methods to reduce the light-off time in catalysts are generally classified into active or passive systems. Typical active systems include electrically heated catalysts [16], fuel burners [17], secondary air injection [18], and after-burners [19], all of which require an extra energy supply. In contrast, passive systems rely mainly on thermal management of the energy obtained from exhaust gases (e.g.…”

Section: Introductionmentioning

confidence: 99%

Experimental study of exhaust temperature variation in a homogeneous charge compression ignition engine

Shahbakhti¹,

Ghazimirsaied

Koch

2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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Homogeneous charge compression ignition (HCCI) engines have low nitrogen oxide and particulate matter engine-out emissions but have higher unburned hydrocarbon and carbon monoxide emissions than the conventional spark ignition (SI) and diesel engines do. Only for sufficiently high exhaust gas temperatures can an exhaust after-treatment be used; thus a low exhaust gas temperature in certain operating conditions can limit the operating range in HCCI engines. The influences of the engine conditions on the exhaust gas temperature in a single-cylinder experimental engine are investigated at 340 steady state operating points. The variation in the exhaust gas temperature is also studied under transient conditions and during mode switching between SI and HCCI combustion. For the conditions tested, a significant number of data have an exhaust gas temperature below 300°C which is below the light-off temperature of typical catalytic converters on the market. Three different categories of engine variables are recognized and classified by how the exhaust temperature is affected by changing that variable. The first category is defined as the primary variables (e.g. the intake pressure and the fuel octane number) for which the location of ignition timing is the dominant factor in influencing the exhaust temperature. The other groups include compounding variables such as the engine speed and opposing variables such as the intake temperature, the coolant temperature, and the equivalence ratio. In addition, experimental results show that the exhaust temperature for HCCI engines is not strongly dependent on the engine load, unlike that for SI engines where the engine load is a main factor in determining the exhaust temperature.

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“…For any given journey, the first 150 s after the engine start will account for a large proportion of the total emissions produced. A study by Konstantinidis et al 1 found that, for a vehicle equipped with a 2.0 l spark ignition engine and a three-way catalytic converter, the initial 150 s of the urban portion 800 s long of the New European Drive Cycle produced approximately 71% of the CO emissions and 55% of the HC emissions. This is due to the time taken for the catalyst to attain 'light-off', which is signified by the point at which the catalyst reaches a sufficiently high temperature to allow chemical reactions to occur.…”

Section: Introductionmentioning

confidence: 99%

Analysis and empirical modelling to assess and predict the impact of catalyst light-off strategies on the exhaust gas temperatures of spark ignition engines

Bannister

Taylor

2014

Proceedings of the Institution of Mechanical Engineers, Part D:

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In order to conform to stringent emissions legislation, three-way catalysts have been routinely fitted to gasolinepowered vehicles in order to reduce the emissions of carbon monoxide, unburned hydrocarbons and nitrogen oxides. In Europe the majority of all personal car journeys are less than 4 km in length, with the emissions produced in the first kilometre accounting for 80% of the total emissions produced in that journey. This is due to the time taken for the catalyst to attain 'light-off' signified by the point at which a catalyst reaches a sufficiently high temperature to allow chemical reactions to occur. There are a number of methods used to reduce the light-off time such as retarded spark timing, higher idle speeds, artificial loading of the engine, secondary air injection and l control. While numerous studies have investigated light-off strategies in isolation, or in limited combinations, this study is the first in the open literature to examine all the above factors simultaneously and to assess how their impacts on the exhaust gas temperatures varies with the distance away from the exhaust ports. Experimental work was undertaken in order to generate empirical models to predict the effects of the catalyst heating strategies of gasoline engines on the light-off times of the production three-way catalyst and the exhaust gas temperatures at various distances along the exhaust system up to, and including, the inlet to the catalyst. The empirical model demonstrated good accuracy with errors in the temperature predictions, when compared with experimental data, found to be, on average, less than 20.6% at the pre-catalyst location.

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Computer aided assessment and optimization of catalyst fast light-off techniques

Cited by 15 publications

References 17 publications

Statistical uncertainty in automotive emissions testing

Statistical uncertainty in automotive emissions testing

Experimental study of exhaust temperature variation in a homogeneous charge compression ignition engine

Analysis and empirical modelling to assess and predict the impact of catalyst light-off strategies on the exhaust gas temperatures of spark ignition engines

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