Smoothing HCCI Heat-Release Rates Using Partial Fuel Stratification with Two-Stage Ignition Fuels

Sjöberg, Magnus; Dec, John E.

doi:10.4271/2006-01-0629

Cited by 216 publications

(102 citation statements)

References 34 publications

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“…Subsequent direct injections occur during the compression stroke to create slight levels of fuel stratification in an attempt to create sequential autoignition events while maintaining ultra-low NOx and soot emissions. [15][16][17][18][19][20][21][22][23][24][25][26][27][28] MFS increases the stratification level by reducing to the amount of premixed fuel and typically features all direct injections during the compression stroke. In addition, MFS strategies typically feature a fuel injection event near top dead center (TDC) of the compression stroke to trigger combustion.…”

Section: Fuel Stratification Levels For Ltgcimentioning

confidence: 99%

A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

Dempsey

Curran

Wagner

2016

International Journal of Engine Research

140

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Many research studies have shown that low temperature combustion in compression ignition engines has the ability to yield ultra-low NOx and soot emissions while maintaining high thermal efficiency. To achieve low temperature combustion, sufficient mixing time between the fuel and air in a globally dilute environment is required, thereby avoiding fuel-rich regions and reducing peak combustion temperatures, which significantly reduces soot and NOx formation, respectively. It has been demonstrated that achieving low temperature combustion with diesel fuel over a wide range of conditions is difficult because of its properties, namely, low volatility and high chemical reactivity. On the contrary, gasoline has a high volatility and low chemical reactivity, meaning it is easier to achieve the amount of premixing time required prior to autoignition to achieve low temperature combustion. In order to achieve low temperature combustion while meeting other constraints, such as low pressure rise rates and maintaining control over the timing of combustion, in-cylinder fuel stratification has been widely investigated for gasoline low temperature combustion engines. The level of fuel stratification is, in reality, a continuum ranging from fully premixed (i.e. homogeneous charge of fuel and air) to heavily stratified, heterogeneous operation, such as diesel combustion. However, to illustrate the impact of fuel stratification on gasoline compression ignition, the authors have identified three representative operating strategies: partial, moderate, and heavy fuel stratification. Thus, this article provides an overview and perspective of the current research efforts to develop engine operating strategies for achieving gasoline low temperature combustion in a compression ignition engine via fuel stratification. In this study, computational fluid dynamics modeling of the in-cylinder processes during the closed valve portion of the cycle was used to illustrate the opportunities and challenges associated with the various fuel stratification levels.

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Section: Fuel Stratification Levels For Ltgcimentioning

confidence: 99%

A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

Dempsey

Curran

Wagner

2016

International Journal of Engine Research

140

View full text Add to dashboard Cite

show abstract

“…Fuel is injected into the cylinder during the compression process and combustion behavior is affected by the injection timing [1,2]. The incomplete mixing of the injected fuel provides a stratification which could relax the maximum pressure rise rate (MPRR) encountered in homogeneous charge compression ignition (HCCI) engines under high load [3,4]. The nature of heat release in these PPCI engine, however, has not been well defined.…”

Section: Introductionmentioning

confidence: 99%

“…Gasoline engines running in the partially premixed compression ignition mode have the potential of high efficient and low emissions at high load [1][2][3][4]. Fuel is injected into the cylinder during the compression process and combustion behavior is affected by the injection timing [1,2].…”

Section: Introductionmentioning

confidence: 99%

The Nature of Heat Release in Gasoline PPCI Engines

Sang¹,

Cheng²,

Maria³

2014

SAE Technical Paper Series

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The heat release characteristics in terms of the maximum pressure rise rate (MPRR) and combustion phasing in a partially premixed compression ignition (PPCI) engine are studied using a calibration gasoline. Early port fuel injection provides a nearly homogeneous charge, into which a secondary fuel pulse is added via direct injection (DI) to provide stratification which is affected by the timing of the start of injection (SOI). As the SOI the DI fuel is retarded from early compression, MPRR first decreases, then increases substantially, and decreases again. The MPRR correlates mostly with the combustion phasing. The SOI timing plays an indirect role. The observation is explained by a bulk heat release process of which the rate increases with temperature rather than by a sequential ignition process. Observations from compression ignition of representative homogeneous charges in a Rapid Compression Machine support this explanation.

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“…This combustion mode represents a transition between the conventional diffusioncontrolled combustion in CI engines and the Premixed Charge Compression Ignition (PCCI) concept, meaning that fuel and air are mixed before combustion, but the charge is not completely homogeneous [11]. Recently, Sjöberg et al [12] confirmed how partial fuel stratification might be a promising method to control the heat release rate in this combustion mode. Partially Premixed Combustion provides the potential of simultaneous reduction of NOx and soot for CI engines, while fuel consumption and efficiency are improved.…”

Section: Introductionmentioning

confidence: 90%

An investigation of partially premixed compression ignition combustion using gasoline and spark assistance

Benajes

García

Domenech

et al. 2013

Applied Thermal Engineering

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Abstract:Nowadays the automotive scientific community and companies are focusing part of their efforts on the investigation of new combustion modes in CI engines, mainly based on the use of locally lean air-fuel mixtures. This characteristic, combined with exhaust gas recirculation, provides low combustion temperatures that reduce pollutant formation. However these combustion concepts have some shortcomings, related to combustion phasing control and combustion stability under the light load engine operating range which must be overcome. The aim of this work is focused on the study of the integration of phasing and cycle-to-cycle repeatability control by means of an ignition spark plug system in a CI engine working under partially premixed charge (PPC) in order to overcome the lack of combustion stability in light load conditions when very low fuel reactivity is used. To achieve this objective, experimental tests have been carried out in a single cylinder optical engine combining broadband luminosity images with cylinder pressure derived heat release rate analysis. Research results reveals the spark assistance as a proper methodology to provide temporal and spatial control over the combustion process solving the lack of cycle to cycle control on the highly premixed compression ignition modes overall in light loads with high ON fuels. Additionally, different stages have been identified in the combustion mode. The process starts with the spark discharge, which produces a flame kernel around the spark plug that later evolves to a premixed flame front. This premixed flame front heats unburned mixture and progresses into an auto-ignition combustion that burns out the rest of the charge with higher light intensity and finally an extinction of combustion process. Finally, the effect of injected fuel mass in the combustion mode has been also tested. An increase in the injected fuel mass has a positive effect on the assistance of the spark at the combustion process for both, combustion stability and cycle to cycle control.

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Smoothing HCCI Heat-Release Rates Using Partial Fuel Stratification with Two-Stage Ignition Fuels

Cited by 216 publications

References 34 publications

A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

A perspective on the range of gasoline compression ignition combustion strategies for high engine efficiency and low NOx and soot emissions: Effects of in-cylinder fuel stratification

The Nature of Heat Release in Gasoline PPCI Engines

An investigation of partially premixed compression ignition combustion using gasoline and spark assistance

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