Increasing EGR Tolerance using High Tumble in a Modern GTDI Engine for Improved Low-Speed Performance

Wheeler, Jennifer; Polovina, Dusan; Ramanathan, S.; Roth, Kevin D; Manning, Dennis M.; Stein, Joshua D.

doi:10.4271/2013-01-1123

Cited by 27 publications

(6 citation statements)

References 19 publications

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“…At highly diluted conditions, improving the control of FP is more important than that of AI. Wheeler et al 19 pointed out that the cooled exhaust gas recirculation (EGR) can cause slower FP, leading to poor engine stability and even misfires. Due to the dilution effect of EGR, both the FP speed and direction varied in continuous cycles of SCHC, which were observed by Xie et al 20 through chemiluminescence flame imaging.…”

Section: Introductionmentioning

confidence: 99%

Control and optimization of spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition

Chen

Wang

Zhao

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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Spark ignition–controlled auto-ignition hybrid combustion, also known as spark assisted compression ignition, is of considerable interest in gasoline engines because of its potential to enlarge the operating range of gasoline diluted combustion. However, it was found that the spark ignition–controlled auto-ignition hybrid combustion process was often characterized with large cycle-to-cycle variations. In this research, a new approach by combining the traditional second-order derivative method and Wiebe function fitting method was proposed to identify different heat release stages of spark ignition–controlled auto-ignition hybrid combustion. The heat release characteristics of the spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition strategy and its control methods were investigated in detail. The effect of control parameters, including spark timing, direct injection ratio and dilution strategy, on improving the thermal efficiency and decreasing the variation of heat release trace in spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition strategy was analysed. The advance of flame propagation ending point and the increase in the average heat release rate in flame propagation stage benefitted the fuel economy and reduced the variations of heat release in spark ignition–controlled auto-ignition hybrid combustion. Although the increase in direct injection ratio contributed to the stability of heat release in the spark ignition–controlled auto-ignition hybrid combustion based on the stratified flame ignition strategy, the thermal efficiency of spark ignition–controlled auto-ignition hybrid combustion cannot be effectively optimized due to the decrease in combustion efficiency. The application of exhaust gas recirculation and air dilution could decrease the variations of heat release process and increase the thermal efficiency of spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition strategy.

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Section: Introductionmentioning

confidence: 99%

Control and optimization of spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition

Chen

Wang

Zhao

et al. 2018

Proceedings of the Institution of Mechanical Engineers, Part D:

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“…However, EGR also slowed the flame kernel growth because of slowed reaction rates. Therefore, higher EGR levels in SI engines might require the incorporation of different higher turbulence combustion chamber flows to increase EGR tolerance, as shown by Wheeler at al., or through high-energy long spark systems, as shown by Alger et al These previous studies suggest that there are technical challenges that need to be addressed for implementation with current market fuels if EGR is to be used.…”

Section: Introductionmentioning

confidence: 99%

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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“…The amount of EGR dilution that can be used is limited, because of cycle-to-cycle combustion instability, thereby limiting the potential efficiency benefit of EGR. − The root cause of the cyclic instability with EGR has been linked to a decrease in flame speed, which elongates the initial flame kernel development process, making it more susceptible to stochastic turbulence variation. − While several technologies unrelated to fuel reforming are being developed to extend the EGR dilution limit, including high-energy long-duration ignition systems and incorporation of different higher turbulence combustion chamber flows, the focus of this work is to extend the EGR dilution limit by using the reformed products of the fuel to increase the EGR dilution tolerance.…”

Section: Introductionmentioning

confidence: 99%

Catalytic Exhaust Gas Recirculation-Loop Reforming for High Efficiency in a Stoichiometric Spark-Ignited Engine through Thermochemical Recuperation and Dilution Limit Extension, Part 1: Catalyst Performance

et al. 2018

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The use of fuel reformate from catalytic processes is known to have beneficial effects on the spark-ignited combustion process through enhanced dilution tolerance and decreased combustion duration, but, in many cases, reformate generation can incur a significant fuel penalty. In this two-part investigation, we demonstrate that efficient catalytic fuel reforming can result in improved brake engine efficiency while maintaining stoichiometric exhaust under the right conditions. In Part 1 of this investigation, we used a combination of thermodynamic equilibrium calculations and experimental fuel catalytic reforming measurements on an engine to characterize the best possible reforming performance and energetics over a range of equivalence ratios and O2 concentrations. Ideally, one might expect the highest levels of thermochemical recuperation for the highest catalyst equivalence ratios. However, reforming under these conditions is highly endothermic, and the available enthalpy for reforming is constrained. Thus, for relatively high equivalence ratios, more methane and less H2 and CO are produced. Our experiments revealed that this suppression of H2 and CO could be countered by adding small amounts of O2, yielding as much as 15 vol % H2 at the catalyst outlet for 4 < Φcatalyst < 7 under quasi-steady-state conditions. Under these conditions, the H2 and CO yields were highest and there was significant water consumption, confirming the presence of steam reforming reactions. Analyses of the experimental catalyst measurements indicated the possibility of both endothermic and exothermic reaction stages and global reaction rates sufficient to enable the utilization of higher space velocities than those employed in our experiments. In a companion paper detailing Part 2 of this investigation, we present results for the engine dilution tolerance and brake engine efficiency impacts of the reforming levels achieved.

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Increasing EGR Tolerance using High Tumble in a Modern GTDI Engine for Improved Low-Speed Performance

Cited by 27 publications

References 19 publications

Control and optimization of spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition

Control and optimization of spark ignition–controlled auto-ignition hybrid combustion based on stratified flame ignition

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

Catalytic Exhaust Gas Recirculation-Loop Reforming for High Efficiency in a Stoichiometric Spark-Ignited Engine through Thermochemical Recuperation and Dilution Limit Extension, Part 1: Catalyst Performance

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