Challenges for Spark Ignition Engines in Heavy Duty Application: a Review

Mahendar, Senthil Krishnan; Erlandsson, Anders Christiansen; Adlercreutz, Ludvig

doi:10.4271/2018-01-0907

Cited by 25 publications

(9 citation statements)

References 71 publications

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“…To improve efficiency further in HD SI engines, some methods have been compiled and discussed in a previous publication. 49 EGR could potentially offer higher dilution level compared to excess air 36,41 thereby improving efficiency. Using EGR, dilution can be achieved at global stoichiometric air fuel ratio and a three way catalyst can be used thereby simplifying the after treatment architecture.…”

Section: Discussionmentioning

confidence: 99%

“…Mixed results for stability are reported comparing gasoline and ethanol 31,[45][46][47][48] and are elaborated in a previous work. 49 Ethanol, with a higher HOV, results in lower temperature at spark timing than gasoline and hence potentially lower stability. On the other hand, ethanol is more volatile and has a marginally higher laminar flame speed which should reduce instability.…”

Section: Introductionmentioning

confidence: 99%

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Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Mahendar

Larsson

Erlandsson

2020

International Journal of Engine Research

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Knock is the most crucial limitation in attaining the peak load required at high efficiency in heavy duty (HD) spark ignition (SI) engines. Renewable fuels such as ethanol and methanol have high resistance to autoignition and can help overcome this limitation. To reduce knock and improve efficiency further, dilution can be used to add specific heat capacity and reduce combustion temperature. This work studied diluted combustion and knock characteristics of gasoline, ethanol, and methanol on a HD SI single cylinder engine for a wide load range. Ethanol and methanol displayed excellent knock resistance which allowed a peak gross IMEP of 25.1 and 26.8 bar respectively, compared to gasoline which only reached 8.3 bar at [Formula: see text]1.4 with a compression ratio of 13. Over 18% increase in gross IMEP was possible for gasoline and ethanol when increasing air excess ratio from 1 to 1.4. Methanol achieved the target gross IMEP at [Formula: see text]1 and required no spark retard at [Formula: see text]1.6. A peak indicated efficiency above 48% was recorded for ethanol and methanol at [Formula: see text]1.6 and gross IMEP of approximately 21 bar. At part loads, stable operation was possible until [Formula: see text]1.8 for all fuels. Increase in intake temperature showed a marginal improvement in stability but no increase in lean limit. The concept shows promise as diluted combustion of ethanol and methanol reduced knock and achieved diesel baseline load. With optimization, there is potential to improve efficiency further and possible cost savings compared to commercial diesel engines.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Mahendar

Larsson

Erlandsson

2020

International Journal of Engine Research

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“…Yue et al [14] found that increasing flame speed shows a negative impact on knock mitigation, but provides improvement on thermal efficiency by shortening the combustion duration. However, some research [15,16] shows that relatively low turbulence intensity gives the longer residence time for end-gas auto-ignition occurrence, thus knock is intensified. This contrast manifests that the underlying mechanism of the effects of flame propagation speed on auto-ignition is unclear.…”

Section: Of 23mentioning

confidence: 99%

Effects of Flame Propagation Velocity and Turbulence Intensity on End-Gas Auto-Ignition in a Spark Ignition Gasoline Engine

et al. 2020

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Knocking is a destructive and abnormal combustion phenomenon that hinders modern spark ignition (SI) engine technologies. However, the in-depth mechanism of a single-factor influence on knocking has not been well studied. Thus, the major aim of the present study is to study the effects of flame propagation velocity and turbulence intensity on end-gas auto-ignition through a large eddy simulation (LES) and a decoupling methodology in a downsized gasoline engine. The mechanisms of end-gas auto-ignition as well as strong pressure oscillation are qualitatively analyzed. It is observed that both flame propagation velocity and turbulence have a non-monotonic effect on knocking intensity. The competitive relationship between flame propagation velocity and ignition delay of the end gas is the primary reason responding to this phenomenon. A higher flame speed leads to an increase in the heat release rate in the cylinder, and consequently, quicker increases in the temperature and pressure of the unburned end-gas mixture are obtained, leading to end-gas auto-ignition. Further, the coupling of a pressure wave and an auto-ignition flame front results in super-knocking with a maximum peak of pressure of 31 MPa. Although the turbulence indirectly influences the end-gas auto-ignition by affecting the flame propagation velocity, it can accelerate the dissipation of radicals and heat in the end gas, which significantly influences knocking intensity. Moreover, it is found that the effect of turbulence is more pronounced than that of flame propagation velocity in inhibiting knocking. It can be concluded that the intensity of the pressure oscillation depends on the unburned mixture mass as well as the local thermodynamic state induced by flame propagation and turbulence, with mutual interactions. The present work is expected to provide valuable perspective for inhibiting super-knocking of an SI gasoline engine.

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“…Stoichiometric SI engines are able to achieve the lowest overall emissions of NO x and unburned hydrocarbons (HC) because of the benefit of a three-way catalyst (TWC) and has been the preferred strategy to achieve Euro VI regulations. 9 A significant and perhaps prohibitive limitation of lean-burn strategies are excessive HC emissions, which are primarily methane 10,11 that cannot be easily treated with an oxidation catalyst due to low exhaust temperatures. 12,13 Catalysts are also unable to treat NO x due to high exhaust oxygen concentration.…”

Section: Introductionmentioning

confidence: 99%

The fundamental effects of in-cylinder evaporation of liquefied natural gas fuels in engines

Finneran

Garner

Nadal

2020

Proceedings of the Institution of Mechanical Engineers, Part D:

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Liquefied natural gas is emerging as viable and potentially sustainable transportation fuel with intrinsic economic and environmental benefits. Liquefied natural gas possesses thermomechanical exergy amounting to ∼1 MJ kg-1 which is currently wasted on liquefied natural gas vehicles, while it could be used to produce useful work. The present investigation proposes an indirect means of obtaining useful work from liquefied natural gas through charge cooling and also demonstrates additional benefits in terms of NOx emissions and power density. A thermodynamic engine model was used to quantify the performance benefits of such a strategy for a homogeneous-charge, spark-ignited, stoichiometric natural gas engine. Four fuelling strategies were compared in terms of fuel consumption, mean effective pressure and NOx emissions. Compared to the conventional port-injected natural gas engine (where gaseous fuel is injected), it was found that directly injecting the liquid phase fuel into the cylinder near the start of the compression stroke resulted in approximately -8.9% brake specific fuel consumption, +18.5% brake mean effective pressure and -51% brake specific NOx depending on the operating point. Port-injection of the fuel in the liquid phase carried similar benefits, while direct injection of the fuel in the gaseous phase resulted in minor efficiency penalties (∼+1.3% brake specific fuel consumption). This work highlights the future potential of liquefied natural gas vehicles to achieve high specific power, high efficiency and ultra-low emissions (such as NOx) by tailoring the fuel system to fully exploit the cryogenic properties of the fuel.

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Challenges for Spark Ignition Engines in Heavy Duty Application: a Review

Cited by 25 publications

References 71 publications

Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Alcohol lean burn in heavy duty engines: Achieving 25 bar IMEP with high efficiency in spark ignited operation

Effects of Flame Propagation Velocity and Turbulence Intensity on End-Gas Auto-Ignition in a Spark Ignition Gasoline Engine

The fundamental effects of in-cylinder evaporation of liquefied natural gas fuels in engines

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