Development of a Fuel Injection Strategy for Diesel LTC

Ojeda, William De; Zoldak, Phil; Espinosa, Raul; Kumar, Rajesh

doi:10.4271/2008-01-0057

Cited by 45 publications

(21 citation statements)

References 10 publications

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“…With highly reactive fuels, like diesel, it is difficult to achieve sufficient premixing prior to autoignition, which has been shown in previous studies. 4,[9][10][11] Regardless of the fuel properties, PCCI combustion modes have been shown to have challenges associated with limited operable load range, poor combustion efficiency, combustion timing controllability, and high pressure rise rates leading to high combustion noise. In an effort to address these challenges while maintaining low NOx and soot emissions, researchers have been using various levels of in-cylinder fuel stratification (i.e.…”

Section: Ltc Operability and Fuel Properties: Gasoline And Diesel Fuelmentioning

confidence: 99%

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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

136

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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: Ltc Operability and Fuel Properties: Gasoline And Diesel Fuelmentioning

confidence: 99%

“…7 On the contrary, diesel fuels are highly reactive due to the long, saturated molecular structures (i.e. carbon number in the range of [10][11][12][13][14][15][16][17][18][19][20] and thus autoignite readily, making it difficult to achieve LTC.…”

Section: Ltc Operability and Fuel Properties: Gasoline And Diesel Fuelmentioning

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

136

View full text Add to dashboard Cite

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“…Recently reviewed by Musculus et al [1] and investigated for applications in both light-duty [2][3][4][5][6] and heavy-duty [7][8][9][10] engines, LTC uses a combination of greater dilution and premixing of reactant mixtures compared to conventional diesel combustion [11] to suppress formation of NO x and soot. One common method of dilution is exhaust gas recirculation (EGR), which introduces high-heat-capacity species such as CO 2 and H 2 O into the cylinder, reduces the flame temperature, * Corresponding author.…”

Section: Introductionmentioning

confidence: 99%

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

O’Connor

Musculus

Pickett

2016

Combustion and Flame

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a b s t r a c tThis work explores the mechanisms by which a post injection can reduce unburned hydrocarbon (UHC) emissions in heavy-duty diesel engines operating at low-temperature combustion conditions. Post injections, small, close-coupled injections of fuel after the main injection, have been shown to reduce UHC in the authors' previous work. In this work, we analyze optical data from laser-induced fluorescence of both CH 2 O and OH and use chemical reactor modeling to better understand the mechanism by which post injections reduce UHC emissions. The results indicate that post-injection efficacy, or the extent to which a post injection reduces UHC emissions, is a strong function of the cylinder pressure variation during the post injection. However, the data and analysis indicate that the pressure and temperature rise from the post injection combustion cannot solely explain the UHC reduction measured by both engine-out and optical diagnostics. The fluid-mechanic, thermal, and chemical interaction of the post injection with the main-injection mixture is a key part of UHC reduction; the starting action of the post jet and the subsequent entrainment of surrounding gases are likely both important processes in reducing UHC with a post injection.

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“…For example, low-temperature combustion (LTC) operation using high levels of exhaust gas recirculation (EGR) has been shown to significantly reduce PM and NOx emissions [5][6][7][8]. For example, low-temperature combustion (LTC) operation using high levels of exhaust gas recirculation (EGR) has been shown to significantly reduce PM and NOx emissions [5][6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Effect of Load on Close-Coupled Post-Injection Efficacy for Soot Reduction in an Optical Heavy-Duty Diesel Research Engine

O’Connor

Musculus

2014

Journal of Engineering for Gas Turbines and Power

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A s s is ta n t P ro fe sso r M e c h a n ic a l and N uclear E n g in e e rin g D epartm ent, C enter fo r C o m b u s tio n , P ow er and P ro p u ls io n , P e n nsylva nia State U nive rsity, 111 R esearch East B u ild in g , U n iv e rs ity Park, PA 1 6 8 0 2 e -m a il: jx o 2 2 @ e n g r.p s u .e d u M a rk M usculusT e ch n ica l S taff E n g in e C o m b u s tio n D epartm ent, C o m b u s tio n Research F a cility, S andia N ational Lab o ra to rie s, P.O. B ox 969 , M S 9 05 3 , L iv e rm o re , C A 94551 e -m a il: m p m u s c u @ s a n d ia .g o vThe use o f close-coupled post injections is an in-cylinder sOot-reduction technique that has much promise for high efficiency heavy-duty diesel engines. Close-coupled post injec tions, short injections o f fuel that occur soon after the end of the main fuel injection, have been known to reduce engine-out soot at a wide range of engine operating conditions, including variations in injection timing, exhaust gas recirculation (EGR) level, load, boost, and speed. While many studies have investigated the performance of post injections, the details of the mechanism by which soot is reduced remains unclear. In this study, we have measured the efficacy of post injections over a range of load conditions, at constant speed, boost, and rail pressure, in a heavy-duty optically-accessible research diesel engine. Here, the base load is varied by changing the main-injection duration. Measurements of engine-out soot indicate that not only does the efficacy of a post injection decrease at higher engine loads, but that the range of post-injection durations over which soot reduction is achievable is limited at higher loads. Optical measurements, including the natural luminescence of soot and planar laser-induced incandescence of soot, provide information about the spatiotemporal development of in-cylinder soot through the cycle in cases with and without post-injections. The optical results indicate that the post injection behaves similarly at different loads, but that its relative efficacy decreases due to the increase in soot resulting from longer main-injection durations.

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Development of a Fuel Injection Strategy for Diesel LTC

Cited by 45 publications

References 10 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

Effect of post injections on mixture preparation and unburned hydrocarbon emissions in a heavy-duty diesel engine

Effect of Load on Close-Coupled Post-Injection Efficacy for Soot Reduction in an Optical Heavy-Duty Diesel Research Engine

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