Methanol-gasoline Dual-fuel Spark Ignition (DFSI) combustion with dual-injection for engine particle number (PN) reduction and fuel economy improvement

Liu, Hui; Wang, Zhi; Yan, Linbo; Xiang, Shouzhi; Wang, Jianxin; Wagnon, Scott W.

doi:10.1016/j.energy.2015.06.051

Cited by 61 publications

(14 citation statements)

References 28 publications

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“…The extended Zel'dovich mechanism is used to predict the thermal NOx emissions [27]. Although the prediction of PM emissions is absent in this study, the previous studies [28,29] provide the confidence that the PM emissions would be kept at a very low level in methanol DISI engines.…”

Section: Numerical Modelmentioning

confidence: 94%

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Bai

Tunér

et al. 2019

Applied Thermal Engineering

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This paper reports an investigation of a highly stratified methanol direct injection spark ignition (DISI) engine with a high compression ratio. The effects of the start of injection (SOI), spray-included angle, injection pressure, and spark timing (ST) on in-cylinder flow, fuel distribution, flame propagation, and engine performance are evaluated in detail. The combustion process of methanol DISI engine is very sensitive to the variation of SOI, which is closely associated with the in-cylinder turbulence and the fuel/air mixing. It is found that retarding SOI shows the similar effects on combustion process as reducing spray-included angle, which indicates that the effects of SOI are more related to the spray target (i.e., fuel distribution). The injection pressure affects the combustion process mainly through the impact on the fuel distribution in the cylinder. The flame propagates from the spark plug towards the cylinder axis along the in-cylinder swirl direction, and more fuel mass in the piston bowl promotes the flame propagation. Thus, more retarded SOI, smaller spray-included angle, and lower injection pressure are suggested at low loads to enrich the fuel concentration in the bowl to achieve a stable combustion. Under medium load, indicated thermal efficiency (ITE), peak pressure rise rate (PPRR), and nitrogen oxides (NOx) emissions can be improved with advanced SOI. ITE can also be improved by advancing ST with a slight penalty on PPRR and NOx. This study demonstrates the potential of simultaneously optimizing fuel injection and ST to improve engine performance.

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Section: Numerical Modelmentioning

confidence: 94%

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Bai

Tunér

et al. 2019

Applied Thermal Engineering

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“…Gasoline with higher energy density is directly injected into the cylinder, forming the ideal mixture concentration distribution for fast load response and higher load. 24 Kim et al 25 studied the combustion and emission characteristics of dual-injection strategy with PI of ethanol and DI of gasoline on a direct-injection spark-ignition (DISI) engine. It was found that when the compression ratio varied from 9.5 to 13.3, more ethanol was needed to suppress the knock.…”

Section: Introductionmentioning

confidence: 99%

Co-effects of fuel research octane number and ethanol injection ratio on dual-fuel spark-ignition engine

Feng

Jiang

et al. 2019

International Journal of Engine Research

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The combustion and emission characteristics of a dual-fuel spark-ignition engine with direct injection of gasoline surrogates and port injection of ethanol were studied. Toluene reference fuel with different research octane number namely TRF#1, TRF#2, TRF#3, TRF#4 and TRF#5 were employed as gasoline surrogates, in which TRF#1 with high octane number was to simulate commercial gasoline under direct-injection spark-ignition mode as comparison. For dual-fuel spark-ignition mode, the ethanol port-injection ratios were 21%, 25%, 29%, 32% and 35%, respectively. The results demonstrated that with the increase of the ethanol ratio, the knock-limited spark timing was advanced gradually. The emissions of hydrocarbon, ethane, propylene, isopentane, cyclohexane and aromatic hydrocarbons reduced while CO, NOx, ethylene, acetaldehyde and ethanol increased. Compared to TRF#1 in direct-injection spark-ignition mode, the indicated thermal efficiencies of dual-fuel spark-ignition mode were slightly lower under most test conditions. When direct injection of TRF#3, TRF#4, TRF#5 and the ethanol ratio was higher than 29%, some of the indicated thermal efficiencies of the engine were consistent with or higher than that of TRF#1 in direct-injection spark-ignition mode. Based on dual-fuel spark-ignition mode and with the assistance of port injection of ethanol, the indicated thermal efficiency of low research octane number fuels was comparable to that of TRF#1 in direct-injection spark-ignition mode.

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“…Through previous studies, 10 the research of normal combustion, knock, and super-knock in highly boosted gasoline engine could be conducted on an RCM platform associated with optical methods to obtain the pressure traces and images of the whole combustion process. The RCM results show that the combustion process of normal combustion could be summarized as “spark ignition followed by flame propagation,” while knock is “spark ignition followed by deflagration which could induce end-gas auto-ignition followed by pressure oscillation.” 13–15 Furthermore, the detailed combustion process of super-knock includes several steps: 16 (1) pre-ignition before spark ignition; (2) flame propagation induced by pre-ignition; (3) auto-ignition induced by hot-spot in the unburned end-gas mixture, which results in rapid heat release and pressure rise; (4) shock wave induced by the strong end-gas auto-ignition; (5) detonation induced by shock wave and its interaction effects with the wall, the reaction front, or other shock waves; and (6) extremely high pressure oscillation induced by detonation wave propagation. From the process of super-knock, it could be seen that pre-ignition is the inducement of super-knock and detonation is the root of how super-knock could damage engines dramatically.…”

Section: Experimental Setup and Methodologymentioning

confidence: 99%

Super-knock suppression for highly turbocharged gasoline engines using lean mixture control strategy with the same energy density

Liu

Wang

et al. 2019

International Journal of Engine Research

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Super-knock has been the main obstacle to improve power density and engine efficiency of modern gasoline engines. Previous researches show that the key points of super-knock are composed of pre-ignition and detonation. The former is the inducement and the latter is the root reason why super-knock could damage engines dramatically. Lots of studies have been conducted to suppress super-knock by eliminating pre-ignition. Using a rapid compression machine, this work explores the lean mixture control strategy to eliminate detonation and thus suppressing super-knock. Furthermore, a one-dimensional simulation model was set up to investigate the mechanism of how lean mixture could suppress detonation and super-knock. The experimental and simulation results show that based on detonation and super-knock operating condition, adding 80% additional air while keeping the same fuel energy density could transfer combustion from detonation mode to super-sonic auto-ignitive deflagration mode. The peak pressure and pressure oscillation could be reduced significantly. This indicates that boosted lean burn could suppress detonation and thus suppress super-knock effectively, even if pre-ignition occurs. It could be an effective and practical control strategy to protect modern highly turbocharged gasoline engines.

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Methanol-gasoline Dual-fuel Spark Ignition (DFSI) combustion with dual-injection for engine particle number (PN) reduction and fuel economy improvement

Cited by 61 publications

References 28 publications

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Investigation on a high-stratified direct injection spark ignition (DISI) engine fueled with methanol under a high compression ratio

Co-effects of fuel research octane number and ethanol injection ratio on dual-fuel spark-ignition engine

Super-knock suppression for highly turbocharged gasoline engines using lean mixture control strategy with the same energy density

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