The Effect of an External Fuel Injection on the Control of LNT System; the Diesel Nox Reduction System

Nam, Gun-Woo; Park, Jin-Woo; Lee, Jin Ha; Yeo, Gwon-Koo

doi:10.4271/2007-01-1242

Cited by 9 publications

(7 citation statements)

References 7 publications

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“…Among factors affecting the NO x conversion efficiency, the spray SMD might be the most dominant, and it had a vital influence on the NO x conversion efficiency in comparison with other studies. 15,16 Therefore, injector 2 employed in this study was found to be more suitable for the secondary injector in the HC-LNT system since injector 2 could cause the reductant to be more atomized and uniformly distributed in the system.…”

Section: Nox Reduction Characteristicsmentioning

confidence: 98%

“…They reduced NO x emissions from a diesel engine by up to 90% with an approximately 2-3% increase in fuel consumption. 15 A secondary reductant injection system is usually employed to maximize the NO x conversion efficiency in SCR or LNT systems. As for the secondary injection system, while an outwardly pintle-type injector or nozzle has been developed in SCR systems to avoid the deposit of solid urea, a jetspray-type or outwardly pintle-type injector has been developed in LNT systems in which the deposit is not normally an issue.…”

Section: Introductionmentioning

confidence: 99%

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Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

Kim

Lee

2012

Proceedings of the Institution of Mechanical Engineers, Part D:

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Among emission reduction technologies, a hydrocarbon lean nitrogen oxide trap is a cost-effective solution for nitrogen oxide emission control in light-duty vehicles. However, the hydrocarbon lean nitrogen oxide trap leads to high fuel consumption because diesel fuel is normally used as a reducing agent (i.e. a reductant). It is necessary to establish injection conditions corresponding to the maximum nitrogen oxide conversion in the hydrocarbon lean nitrogen oxide trap system. A uniform distribution of the reducing agent is desirable, and the spray characteristics of the reductant, such as atomization and penetration, must be well understood in order to establish a good performance of the hydrocarbon lean nitrogen oxide trap. With this goal in mind, the spray characteristics and behaviour of a port fuel injector with four holes were analysed using visualization and r.m.s. image-processing techniques. The Sauter mean diameter distribution of the injector was measured using a Malvern system. The liquid agents employed in this study were ISO 4113 and n-heptane, which have properties similar to those of diesel and gasoline fuels respectively. These results elucidated the feasibility of a secondary injection system for the hydrocarbon lean nitrogen oxide trap.

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Section: Nox Reduction Characteristicsmentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

Kim

Lee

2012

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…The number of injection determines the total quantity of THC, and the injection frequency determines the concentration of injected reductant. High NOx conversion efficiency, low slip of THC and low reductant consumption can be achieved by optimizing two parameters above 6) . Figure 18 shows the effect of the injection pressure on the spray behavior characteristics in the exhaust gas flow.…”

Section: Distribution Characteristics In the Exhaust Pipe And Nox Redmentioning

confidence: 99%

“…The external injection approach to control the amount of HC agent has several prior benefits: it can be controlled independently without disturbing the engine control, can be adapted to various exhaust system layouts, and has no oil dilution problems 6) .…”

Section: Introductionmentioning

confidence: 99%

A Study on the Optimal Injection Conditions for an HC-LNT Catalyst System with a 12-Hole Type Injector

Lee

2008

JTST

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NOx catalytic converter systems periodically require rich or stoichiometric operating conditions to reduce NOx. The HC (hydrocarbon) concentration in a diesel engine is typically so low that the HC is not sufficient for NOx conversion. It was proposed that a rich air fuel ratio in a diesel engine could be realized via post fuel injection or supplemental fuel injection into the exhaust gas. A new method that optimizes the control of an external HC injection to diesel exhaust pipes for HC type LNT (Lean NOx Trap) catalyst systems has been developed. The external injection has other benefits: it can be controlled independently without disturbing engine control, it can be adapted to various layouts for exhaust systems, it has no oil dilution problems, among other benefits. In this study, the concentration and amount of HC can be controlled via control of the external injection. This research investigated the spray behavior of hydrocarbons injected into the transparent exhaust pipe. From this experiment, we obtained useful information about the optimal injection conditions for the HC-LNT catalyst system with an MPI injector.

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“…In order to make exhaust gas lean or rich, fuel injection into the exhaust gas was used in parallel to engine control [20]. There are two ways to add a reducing agent into exhaust gas.…”

Section: Introductionmentioning

confidence: 99%

Effect of Hydrogen-Enriched Gas as a Reductant on the Performance of a Lean NO_x Trap Catalyst for a Light-Duty Diesel Engine

Park

Kim

Choi

et al. 2010

Proceedings of the Institution of Mechanical Engineers, Part D:

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Direct-injection diesel engines have become prime candidates for future transportation needs owing to their high thermal efficiency. However, the increase in nitrogen oxides (NO x) within local high-temperature regions and the increase in particulate matter within the diffusion flame region during diesel combustion are problematic and must be resolved. The utilization of NO x-absorbing catalysts, based on the concept of NO x storage and release, is one of the most promising techniques able to reduce NO x emissions within net oxidizing gas conditions. This type of NO x removal system, called the lean NO x trap (LNT) catalyst, absorbs NO x under lean exhaust gas conditions and releases NO x under rich conditions. This technology provides the advantage of high NO x conversion efficiency; however, the correct amount of reducing agent must be supplied within the catalytic converter under appropriate conditions in order to guarantee a high NO x reduction efficiency. In this research, the performance characteristics of an LNT, using a hydrogen-enriched gas as a reductant, were examined via various injection strategies and rich exhaust gas conditions. Although the hydrogen concentration of hydrogen-enriched gas also affects the LNT performance, the composition of hydrogen-enriched gas was fixed as a similar composition to that for the ideal re-forming of diesel fuel. The NO x reduction efficiency is closely connected to the injection timing and duration of reductant flow. When the injection was introduced 1.5 s after throttling, the LNT NO x conversion was maximized. However, the LNT NO x conversion decreased when the injection timing was earlier or later than 1.5 s. Because the actual rich duration of the exhaust gas is limited at a specific point during the rich operation for 3 s, the LNT NO x conversion was maximized when the hydrogen-enriched gas was injected at the minimum air-to-fuel ratio observed at the LNT inlet. By optimizing the control of this flow, the system encounters only a 1.9 per cent fuel penalty while maintaining a 90 per cent NO x reduction efficiency.

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The Effect of an External Fuel Injection on the Control of LNT System; the Diesel Nox Reduction System

Cited by 9 publications

References 7 publications

Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

A Study on the Optimal Injection Conditions for an HC-LNT Catalyst System with a 12-Hole Type Injector

Effect of Hydrogen-Enriched Gas as a Reductant on the Performance of a Lean NO_x Trap Catalyst for a Light-Duty Diesel Engine

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The Effect of an External Fuel Injection on the Control of LNT System; the Diesel Nox Reduction System

Cited by 9 publications

References 7 publications

Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

Spray characteristics of four-hole injectors used for a hydrocarbon lean nitrogen oxide catalyst system in a diesel engine

A Study on the Optimal Injection Conditions for an HC-LNT Catalyst System with a 12-Hole Type Injector

Effect of Hydrogen-Enriched Gas as a Reductant on the Performance of a Lean NOx Trap Catalyst for a Light-Duty Diesel Engine

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Product

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Effect of Hydrogen-Enriched Gas as a Reductant on the Performance of a Lean NO_x Trap Catalyst for a Light-Duty Diesel Engine