The Influence of NO on the Combustion Phasing in an HCCI Engine

Risberg, Per; Johansson, David; Andrae, Johan C. G.; Kalghatgi, Gautam; Björnbom, Pehr; Ångström, Hans-Erik

doi:10.4271/2006-01-0416

Cited by 44 publications

(41 citation statements)

References 24 publications

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“…The change is clear at an addition of 10,000 ppm. These calculations show clearly that the addition of CO delays the ignition and thus decreases the overall reactivity as is one of the observations found in the literature [7,15]. It is worth mentioning, though, that a concentration of 10,000 ppm of CO in the inlet of an engine is less likely to occur.…”

Section: The Effect Of Co On the Auto-ignition Processmentioning

confidence: 47%

“…At pressures higher than 5 atm and at fuel-lean conditions (which are for the major part the conditions of an HCCI engine), CO decreased the laminar flame speed. A contradicting observation was made by Subramanian et al [7]. In their work they compared three different kinetic mechanisms in order to find out the influence of CO addition on the auto-ignition delay of mixtures dedicated to HCCI engines.…”

Section: The Global Effects Of Co No and Ch 2 O On The Auto-ignitionmentioning

confidence: 75%

“…CO is formed in, among others, the following reactions and Subramanian et al [7], CO does not have any effect. The reason could well be that the addition concentration is not high enough in order to observe any difference.…”

Section: The Effect Of Co On the Auto-ignition Processmentioning

confidence: 99%

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An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

Machrafi

Cavadias

Guibert

2008

Combustion and Flame

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In order to contribute to the solution of controlling the auto-ignition in a Homogeneous Charge Compression Ignition (HCCI) engine, parameters linked to External Gas Recirculation (EGR) seem to be of particular interest. Experiments performed with EGR present some difficulties in interpreting results using only the diluting and thermal aspect of EGR. Lately, the chemical aspect of EGR is taken more into consideration, because this aspect causes a complex interaction with the dilution and thermal aspects of EGR. This paper studies the influence of EGR on the auto-ignition process and particularly the chemical aspect of EGR.The diluents present in EGR are simulated by N 2 and CO 2 , with dilution factors going from 0 to 46 vol%. For the chemically active species that could be present in EGR, the species CO, The fuels used for the auto-ignition are n-heptane and PRF40. It appeared that CO, in the investigated domain, did not influence the ignition delays, while NO had two different effects.At concentrations up until 45 ppm, NO advanced the ignition delays for the PRF40 and at higher concentrations, the ignition delayed. The influence of NO on the auto-ignition of nheptane seemed to be insignificant, probably due to the higher burn rate of n-heptane. CH 2 O seemed to delay the ignition. The results suggested that especially the formation of OH radicals or their consumption by the chemical additives determine how the reactivity of the auto-ignition changed.

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Section: The Effect Of Co On the Auto-ignition Processmentioning

confidence: 47%

Section: The Global Effects Of Co No and Ch 2 O On The Auto-ignitionmentioning

confidence: 75%

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An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

Machrafi

Cavadias

Guibert

2008

Combustion and Flame

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“…Both of which are significantly dependent on the critical in-cylinder HCCI engine conditions as autoignition is a kinetics dependent phenomenon. The control on the precise start of autoignition under HCCI operation is investigated using different control strategies (Sjoberg and Dec, 1999;Hardy, and Reitz ,2006) and one of the strategies involved in the experimental program is trapping of the burned gas so as to use the controlled unburned gas temperature and use of NO inside it (Risberg et al ,2006).…”

Section: Effects Of Start Of Ignition (Soi)mentioning

confidence: 99%

NOx formation inside HCCI engines

Abdelghaffar¹

2010

AJSIR

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A multizones modeling of the combustion characteristics of the spark assisted homogeneous charge compression ignition (HCCI) engine is performed. The main aim of this work is to deduce the simulation to reveal the in-cylinder conditions prevailing during the spark assisted HCCI combustion which is difficult to obtain experimentally. Conditions such as in-cylinder burned gas temperature, NOx formation, and mean in-cylinder charge temperature and pressure conditions. The second aim of the present work is the mapping of the influence of NO doping on the incylinder conditions. Recent experimental studies have shown that NO has significant impact on hydrocarbon autoignition and the NO formed inside the burned gas can be used for autoignition control of HCCI engine combustion. The tuning of a zero-dimensional multizones phenomenological model is performed separately using experimental data for SI and HCCI operation keeping the same engine parameters, engine speed and air-fuel ratio to maintain simulation similarity. Variation of the burned gas temperatures inside the individual zones due to recompression effects and the formation of NOx inside these zones in a single engine stroke for different engine speed conditions are investigated. The mean unburned gas temperature and pressure conditions before the start of ignition are obtained for different operating conditions. The effect of NO on in-cylinder conditions is done by doping it in the order of one magnitude up.

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“…However, there are two critical problems associated with the HCCI engines: control of the autoignition timing and the combustion rate. There are a number of strategies that have been currently investigated to address the above two critical problems, such as a variable compression ratio (Haraldsson et al, 2002;Sjoberg and Dec, 2003;Diaz and Prasad, 2010;AlKhairi et al, 2011;Risberg et al, 2006) variable valve timing (Kaahaaina et al, 2001) variable intake charge temperature or hot exhaust gas recirculation study (Christensen et al, 1999). The exhaust gas injection in the intake port changes the intake temperature thereby giving a good control on the combustion phasing inside the HCCI engine.…”

Section: Introductionmentioning

confidence: 99%

An Investigation of Compressed Natural Gas Engine for Nitrogen Oxides Reduction

Nasser¹

2012

American Journal of Applied Sciences

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Problem statement:This study describes the use of Reformer Gas (RG) to alter NO x emission in a CNG-fueled HCCI engine. Comparison with diesel, natural gas has a very high octane number (≈120) and high auto-ignition temperature (≈600°C). Composed mostly of methane, natural gas is the only common fuel to manifest relatively pure, single-stage combustion. Other fuels have stronger low-temperature reaction and the required entropy for main stage combustion can be obtained from the low temperature heat release as a result of compression to moderate pressure and temperature. In deviation, the methane molecule resists destruction by free radicals and produces negligible heat release at low temperature. In consequences, in CNG-fueled HCCI engines the activation energy required for auto-ignition must be obtained by extreme levels of charge heating and compression. This causes inherently to a high rate of heat release. HCCI operation with pure CNG fuel was attained but not really practical due to very high NO x production. While HCCI operation is usually described as a low NO x technique, the knocking behavior when running with pure CNG raised the peak combustion temperature to a value well above normal combustion and the critical Zeldovich NO x production threshold, giving very high indicated NO x emissions. Approach: One approach to improving these properties is to convert part of the base CNG fuel to Reformer Gas (RG). In this study, modified COMET engine was operated in HCCI mode using a mixture of CNG fuel and simulated RG (75% H 2 and 25% CO) can be produced on-board from CNG using low current and non-thermal plasma boosted fuel converter. Results: This study shows that despite of having various RG mass fractions, λ was the dominant factor in reducing NO x production and increasing RG mass fraction had only a small effect on increasing NO x . This disconnect between the overall equivalence ratio and RG fraction shows that the real benefit of the RG blending was to enable lean (high) operation. Higher λ also effectively reduced maximum pressure and maximum pressure rate. Conclusion: Note that due to the low achievable power levels, the NO x emissions continue to be high and further combustion enhancements and more controlled combustion would be needed to make the CNG-fuelled HCCI engine practical.

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The Influence of NO on the Combustion Phasing in an HCCI Engine

Cited by 44 publications

References 24 publications

An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

An experimental and numerical investigation on the influence of external gas recirculation on the HCCI autoignition process in an engine: Thermal, diluting, and chemical effects

NOx formation inside HCCI engines

An Investigation of Compressed Natural Gas Engine for Nitrogen Oxides Reduction

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