A Continuous Discharge Ignition System for EGR Limit Extension in SI Engines

Alger, Terrence; Gingrich, Jess; Mangold, Barrett; Roberts, Charles E.

doi:10.4271/2011-01-0661

Cited by 117 publications

(35 citation statements)

References 41 publications

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“…It is well established that the addition of cooled external EGR increases efficiency. 19,21,34 The results presented in this study support previous findings on the effect of EGR. A GTE analysis is useful for determining how EGR impacts thermal losses and combustion processes.…”

Section: ■ Resultssupporting

confidence: 94%

Experimental Investigation of Spark-Ignited Combustion with High-Octane Biofuels and EGR. 1. Engine Load Range and Downsize Downspeed Opportunity

Splitter

Szybist

2014

Energy Fuels

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The present study experimentally investigates spark-ignited combustion with 87 AKI E0 gasoline in its neat form and in midlevel alcohol−gasoline blends with 24% vol/vol isobutanol−gasoline (IB24) and 30% vol/vol ethanol−gasoline (E30). A single-cylinder research engine was used with an 11.85:1 compression ratio, hydraulically actuated valves, laboratory intake air, and was capable of external exhaust gas recirculation (EGR). Experiments were conducted with all fuels to full-load conditions with λ = 1, using both 0% and 15% external cooled EGR. Higher octane number biofuel blends exhibited increased stoichiometric torque capability at this compression ratio, where the unique properties of ethanol enabled a doubling of the stoichiometric torque capability with E30 as compared to 87 AKI, up to 20 bar IMEPg (indicated mean effective pressure gross) at λ = 1. EGR provided thermodynamic advantages and was a key enabler for increasing engine efficiency for all fuel types. However, with E30, EGR was less useful for knock mitigation than gasoline or IB24. Torque densities with E30 with 15% EGR at λ = 1 operation were similar or better than a modern EURO IV calibration turbo-diesel engine. The results of the present study suggest that it could be possible to implement a 40% downsize + downspeed configuration (1.2 L engine) into a representative midsize sedan. For example, for a midsize sedan at a 65 miles/h cruise, an estimated fuel consumption of 43.9 miles per gallon (MPG) (engine out 102 g-CO 2 /km) could be achieved with similar reserve power to a 2.0 L engine with 87AKI (38.6 MPG, engine out 135 g-CO 2 /km). Data suggest that, with midlevel alcohol−gasoline blends, engine and vehicle optimization can offset the reduced fuel energy content of alcohol−gasoline blends and likely reduce vehicle fuel consumption and tailpipe CO 2 emissions. ■ INTRODUCTIONThe Energy Independence and Security Act 1 of 2007 requires that, by year 2022, 36 billion gallons per year of bioderived fuels need to be consumed in transportation. This uptake in bioderived fuels is a more than a 7-fold increase from the 4.7 billion gallons consumed per year when the law was enacted. The rules for complying with this mandate are specified by the U.S. Environmental Protection Agency (EPA) in the Renewable Fuel Standard II (RFS II). 2 When the total transportation energy consumption is analyzed, it is apparent that this legislation increases the usage of biofuels. In 2012 the United States consumed 27.97 quadrillion BTU of energy for transportation, and it is projected to consume 29.24 quadrillion BTU in 2022. 3 Assuming gasoline equivalent energy of 42.8 MJ/kg and density of 740 kg/m, 3 the RFS standard will require an increase in the percentage of transportation energy from biofuels to approximately 14% in 2022 from the approximate 2% in 2007. To date, the RFS II progress has seen more than a doubling of biofuel usage, with the annual recorded share of transportation energy from nonpetroleum sources totaling 4.3% in 2012. Although 2012 was the year wi...

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Section: ■ Resultssupporting

confidence: 94%

Experimental Investigation of Spark-Ignited Combustion with High-Octane Biofuels and EGR. 1. Engine Load Range and Downsize Downspeed Opportunity

Splitter

Szybist

2014

Energy Fuels

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“…9 The results from using this system with their high-efficiency dilute gasoline engine (HEDGE) concept show that 0%-50% mass fraction burned (MFB) duration decreases and combustion stability is improved for 0%-25% external EGR compared to the stock ignition system. 9 An alternative method to reduce knock while maintaining efficiency is to replace or blend gasoline with a higher octane fuel, such as ethanol. Previous work has shown that ethanol-gasoline blends can be used at MBT timing without knock even when the compression ratio and peak brake mean effective pressure (BMEP) are increased from the gasoline baseline.…”

Section: Introductionmentioning

confidence: 98%

Scaling and dimensional methods to incorporate knock and flammability limits in models of high-efficiency gasoline and ethanol engines

Lewis

Ortiz-Soto

Lavoie

et al. 2014

International Journal of Engine Research

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Recent work has shown the utility of using simplified models with prescribed burn rates to assess the potential of advanced combustion strategies to increase engine efficiency. However, this approach can be improved by incorporating knock and flammability limits. This work incorporates such limits using a combination of simplified conceptual models that are based on theoretical understanding of knock and flame phenomenon and calibration with experimental results. Using this method, the ideal (unconstrained) and feasible (constrained by knock and flammability) potential of a high efficiency gasoline and E85 engine are compared against a baseline naturally aspirated gasoline engine. Turbocharging, dilution with EGR, and higher compression ratios are used to increase the efficiency potential of the high efficiency gasoline and E85 engines. Results demonstrate the benefit of using this simplified approach in modeling high efficiency engines: the high efficiency gasoline engine is most limited by knock while the E85 engine is limited much less; also increased EGR can be used for the E85 engine due to the higher flame speeds of ethanol. Fuel economy maps are created for each engine/fuel strategy and evaluated in a vehicle model to obtain fuel economy results. Results comparing feasible engines show that peak brake thermal efficiency (BTE) is increased by 11.4% for the high efficiency gasoline engine and 17.8% for the E85 engine, as compared to the baseline gasoline engine. Projected vehicle fuel economy (energy equivalent) improvements are 30.1% for the high efficiency gasoline, and 40.9% for the E85 engine relative to baseline.

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“…Independent variables include compression ratio (9:1, 10.5:1, and 12:1); fuel water dilution by volume (0%, 20%, 30%, 40%); intake air temperature (22°C, 60°C); air/fuel ratio (stoichiometric to leanstability-limit); spark timing (advanced, maximum brake torque, retarded); and ignition strategy (spark only, spark with microwave). This paper demonstrates the extension of the stable engine operating operation at higher levels of EGR dilution than a traditional spark engine [8]. The increasingly-studied field of plasma-assisted ignition and combustion presents opportunities for a new generation of ignition technology, and will be discussed in the following section.…”

Section: Present Study Of Plasma-assisted Ignition In a Wet Ethanolfumentioning

confidence: 93%

Stability Limit Extension of a Wet Ethanol-fueled SI Engine using a Microwave-assisted Spark

Wolk¹

2015

Adv Automob Eng

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Advanced engines can achieve higher efficiencies and reduced emissions by operating in regimes with diluted fuel-air mixtures and higher compression ratios, but the range of stable engine operation is constrained by combustion initiation and flame propagation when dilution levels are high. An advanced ignition technology that reliably extends the operating range of internal combustion engines will aid practical implementation of nextgeneration high-efficiency engines. The microwave-assisted spark plug under development by Imagineering, Inc. of Japan has previously been shown to expand the stable operating range of gasoline-fueled engines through plasmaassisted combustion, but the factors limiting its operation were not well characterized. The present experimental study has two main goals: (1) to investigate the capability of the microwave-assisted spark plug towards expanding the stable operating range of wet-ethanol-fueled engines, and (2) to examine the factors affecting the extent to which microwaves enhance ignition processes. The stability range is investigated by examining the coefficient of variation of indicated mean effective pressure as a metric for instability, and indicated specific ethanol consumption as a metric for efficiency. Engine efficiency improved when the engine was run at slightly-lean air-fuel ratios, with the onset of instability eventually eliminating efficiency gains associated with lean-burn when mixtures become too dilute. Microwave-assisted ignition reduced dilution-triggered instability, improving efficiency compared to unstable spark-only operation at ultra-lean conditions. Microwave-assisted spark also promotes faster average early flame kernel development when un-enhanced flame kernel development is sufficiently slow. Correlations between microwave-assisted flame development enhancement and calculated in-cylinder parameters suggest a relation between enhancement and the amount of energy deposited into the flame kernel, but scatter prevented derivation of a unifying empirical correlation governing all tested cases.

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A Continuous Discharge Ignition System for EGR Limit Extension in SI Engines

Cited by 117 publications

References 41 publications

Experimental Investigation of Spark-Ignited Combustion with High-Octane Biofuels and EGR. 1. Engine Load Range and Downsize Downspeed Opportunity

Experimental Investigation of Spark-Ignited Combustion with High-Octane Biofuels and EGR. 1. Engine Load Range and Downsize Downspeed Opportunity

Scaling and dimensional methods to incorporate knock and flammability limits in models of high-efficiency gasoline and ethanol engines

Stability Limit Extension of a Wet Ethanol-fueled SI Engine using a Microwave-assisted Spark

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