Methods for Fast Catalytic System Warm-Up During Vehicle Cold Starts

Bernhardt, W; Hoffmann, E.

doi:10.4271/720481

Cited by 8 publications

(1 citation statement)

References 1 publication

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“…Reducing the heat capacity of the exhaust system between the engine and the catalyst, reducing the heat capacity of the catalyst itself, mounting the catalyst very near to the engine exhaust valves have been well-known standard design concepts. 1 To shorten the light-off time of the catalyst, many novel concepts have been proposed; secondary air injection for the catalyst combined with rich combustion, 1,2 the burner/catalyst system for fast warm-up, 3 application of an electric heater 4 and so on. Engine operation conditions also have a large impact on the light-off time of the catalyst, and the effect of retarded ignition on the emissions 5–7 and on the cyclic variations 6,8 are investigated in detail.…”

Section: Introductionmentioning

confidence: 99%

Effects of injection parameters on the amount of wall-wet fuel in a port-fuel-injected spark-ignition engine during cold start

Araki

Sakairi

Kuribara

et al. 2019

International Journal of Engine Research

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In a four-stroke cycle port-fuel-injected spark-ignition engine, a significant portion of unburned hydrocarbons is exhausted during the short period of cold start. The aim of this study is to investigate the physics behind the wall-wet phenomena and its determining parameter as simply as possible even though qualitative to some extent. The test engine is driven at a constant speed of 350 r/min. The fuel injection starts at a certain cycle, and the cycles required for the first ignition is counted. Three gasoline injectors having different atomization characteristics are used for port fuel injection, and the droplet size, the spray angle and the spray velocity are varied independently. The fuel transport phenomena from the injector to the cylinder are characterized by only two parameters, α and β, the mass fraction of the fuel without wall-wet and the mass fraction of the evaporated fuel from liquid films on walls. They are determined so that all the first ignition cycles observed experimentally are consistently reproduced by the model. The value of α is successfully determined for every single injector, and it increases monotonously with the decrease in the Stokes number.

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Section: Introductionmentioning

confidence: 99%

Effects of injection parameters on the amount of wall-wet fuel in a port-fuel-injected spark-ignition engine during cold start

Araki

Sakairi

Kuribara

et al. 2019

International Journal of Engine Research

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Studies on NOx Reduction and Three-Component Catalysts

Bernhardt

1975

The Catalytic Chemistry of Nitrogen Oxides

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Effect of Standard Tuning Parameters on Mixture Homogeneity and Combustion Characteristics in a Hydrogen Direct Injection Engine

LOW-KAME¹,

Oung²,

Meissonnier³

et al. 2023

SAE Technical Paper Series

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<div class="section abstract"><div class="htmlview paragraph">Dihydrogen, as a zero CO2 fuel, is a strong candidate for internal combustion engine to limit global warming. This study shows the impact of standard tuning parameters on mixture homogeneity and combustion characteristics. A 2.2L Diesel engine on which the head was reworked to allow side mounted direct injector and central mounted spark plug was selected. The discussed tests were made at low engine speed and partial load. A spark advance sweep at different air-fuel ratios (λ) was conducted. The exponential relation between λ and NOx emissions is highly marked and extremely low NOx emissions up to 1.7 g/kWh at minimum spark advance for maximum brake torque can be measured. A λ sweep was performed at different starts of injection (SOI). The results show that, depending on the engine speed, a later SOI might lead to lower NOx emissions. For a λ setpoint of 1.8, at 1500 rpm, late SOI leads to 30% higher NOx emissions where at 2500 rpm these emissions are 26% lower. This assessment is explained by the cycle-to-cycle variations. Finally, the second λ sweep, where the rail pressure (Prail) was varied, reveals that maximizing the Prail does not necessarily lower down NOx emissions. At 2500 rpm of engine speed, for richer mixtures than λ = 1.8, the higher Prail leads to higher NOx emissions. Having a lower Prail might lead to a slightly leaner mixture near the spark plug at spark timing. This effect extends the ignition delay thus lower the NOx emissions.</div></div>

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Methods for Fast Catalytic System Warm-Up During Vehicle Cold Starts

Cited by 8 publications

References 1 publication

Effects of injection parameters on the amount of wall-wet fuel in a port-fuel-injected spark-ignition engine during cold start

Effects of injection parameters on the amount of wall-wet fuel in a port-fuel-injected spark-ignition engine during cold start

Studies on NOx Reduction and Three-Component Catalysts

Effect of Standard Tuning Parameters on Mixture Homogeneity and Combustion Characteristics in a Hydrogen Direct Injection Engine

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