Performance, Efficiency and Emissions Assessment of Natural Gas Direct Injection compared to Gasoline and Natural Gas Port-Fuel Injection in an Automotive Engine

The need to further reduce fuel consumption and decrease the output of emissions — in order to be within future emissions legislation — is still an ongoing effort for the development of internal combustion engines. Natural gas is a fossil fuel which is comprised mostly of methane and makes it very attractive for use in internal combustion engines because of its higher knock resistance and higher molar hydrogen-to-carbon ratio compared to gasoline. The current paper compares the combustion and emissions behavior of the test engine being operated on either a representative U.S. market gasoline or natural gas. Moreover, specific in-cylinder blend ratios with gasoline and natural gas were also investigated at part-load and wide open throttle conditions. The dilution tolerance for part-load operation was investigated by adding cooled exhaust gas recirculation. The engine used for these investigations was a single cylinder research engine for light duty application which is equipped with two separate fuel systems. Gasoline was injected into the intake port; natural gas was injected directly into the cylinder to overcome the power density loss usually connected with port fuel injection of natural gas. Injecting natural gas directly into the cylinder reduced both ignition delay and combustion duration of the combustion process compared to the injection of gasoline into the intake port. Injecting natural gas and gasoline simultaneously resulted in a higher dilution tolerance compared to operation on one of the fuels alone. Significantly higher net indicated mean effective pressure and indicated thermal efficiency were achieved when natural gas was directly injected after intake valve closing at wide open throttle, compared to an injection while the intake valves were still open. In general it was shown that the blend ratio and the start of injection need to be varied depending on load and dilution level in order to operate the engine with the highest efficiency or highest load.

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Combustion and Emissions Characteristics of Dual Fuel Premixed Charge Compression Ignition with Direct Injection of Synthetic FT Kerosene Produced from Natural Gas and Port Fuel Injection of n-Butanol

10.4271/2016-01-0787 ◽

2016 ◽

Cited By ~ 4

Author(s):

Valentin Soloiu ◽

Martin Muinos ◽

Spencer Harp ◽

Tyler Naes ◽

Remi Gaubert

Keyword(s):

Natural Gas ◽

Fuel Injection ◽

Direct Injection ◽

Dual Fuel ◽

Compression Ignition ◽

Port Fuel Injection

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Comparison of Gasoline Direct-Injection (GDI) and Port Fuel Injection (PFI) Vehicle Emissions: Emission Certification Standards, Cold-Start, Secondary Organic Aerosol Formation Potential, and Potential Climate Impacts

Environmental Science & Technology ◽

10.1021/acs.est.6b06509 ◽

2017 ◽

Vol 51 (11) ◽

pp. 6542-6552 ◽

Cited By ~ 89

Author(s):

Georges Saliba ◽

Rawad Saleh ◽

Yunliang Zhao ◽

Albert A. Presto ◽

Andrew T. Lambe ◽

...

Keyword(s):

Vehicle Emissions ◽

Fuel Injection ◽

Secondary Organic Aerosol ◽

Direct Injection ◽

Organic Aerosol ◽

Climate Impacts ◽

Gasoline Direct Injection ◽

Aerosol Formation ◽

Port Fuel Injection ◽

Certification Standards

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Comparison of primary aerosol emission and secondary aerosol formation from gasoline direct injection and port fuel injection vehicles

Atmospheric Chemistry and Physics ◽

10.5194/acp-18-9011-2018 ◽

2018 ◽

Vol 18 (12) ◽

pp. 9011-9023 ◽

Cited By ~ 18

Author(s):

Zhuofei Du ◽

Min Hu ◽

Jianfei Peng ◽

Wenbin Zhang ◽

Jing Zheng ◽

...

Keyword(s):

Volatile Organic Compounds ◽

Organic Compounds ◽

Fuel Injection ◽

Direct Injection ◽

Gasoline Direct Injection ◽

Vehicle Exhaust ◽

Port Fuel Injection ◽

Gasoline Vehicles ◽

Volatile Organic ◽

The Impact

Abstract. Gasoline vehicles significantly contribute to urban particulate matter (PM) pollution. Gasoline direct injection (GDI) engines, known for their higher fuel efficiency than that of port fuel injection (PFI) engines, have been increasingly employed in new gasoline vehicles. However, the impact of this trend on air quality is still poorly understood. Here, we investigated both primary emissions and secondary organic aerosol (SOA) formation from a GDI and a PFI vehicle under an urban-like driving condition, using combined approaches involving chassis dynamometer measurements and an environmental chamber simulation. The PFI vehicle emits slightly more volatile organic compounds, e.g., benzene and toluene, whereas the GDI vehicle emits more particulate components, e.g., total PM, elemental carbon, primary organic aerosols and polycyclic aromatic hydrocarbons. Strikingly, we found a much higher SOA production (by a factor of approximately 2.7) from the exhaust of the GDI vehicle than that of the PFI vehicle under the same conditions. More importantly, the higher SOA production found in the GDI vehicle exhaust occurs concurrently with lower concentrations of traditional SOA precursors, e.g., benzene and toluene, indicating a greater contribution of intermediate volatility organic compounds and semi-volatile organic compounds in the GDI vehicle exhaust to the SOA formation. Our results highlight the considerable potential contribution of GDI vehicles to urban air pollution in the future.

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Numerical Studies of Glow Plug Shield on Natural Gas Ignition Characteristics in a CI Engine

ASME 2016 Internal Combustion Engine Fall Technical Conference ◽

10.1115/icef2016-9445 ◽

2016 ◽

Author(s):

Kang Pan ◽

James S. Wallace

Keyword(s):

Natural Gas ◽

Ignition Delay ◽

Fuel Injection ◽

Numerical Study ◽

Direct Injection ◽

Fuel Mixture ◽

Injection Angle ◽

Glow Plug ◽

Gas Ignition ◽

Ignition And Combustion

This paper presents a numerical study on fuel injection, ignition and combustion in a direct-injection natural gas (DING) engine with ignition assisted by a shielded glow plug (GP). The shield geometry is investigated by employing different sizes of elliptical shield opening and changing the position of the shield opening. The results simulated by KIVA-3V indicated that fuel ignition and combustion is very sensitive to the relative angle between the fuel injection and the shield opening, and the use of an elliptical opening for the glow plug shield can reduce ignition delay by 0.1∼0.2ms for several specific combinations of the injection angle and shield opening size, compared to a circular shield opening. In addition, the numerical results also revealed that the natural gas ignition and flame propagation will be delayed by lowering a circular shield opening from the fuel jet center plane, due to the blocking effect of the shield to the fuel mixture, and hence it will reduce the DING performance by causing a longer ignition delay.

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Influence of Charge Motion and Compression Ratio on the Performance of a Combustion Concept Employing In-Cylinder Gasoline and Natural Gas Blending

Volume 1: Large Bore Engines; Fuels; Advanced Combustion ◽

10.1115/icef2017-3661 ◽

2017 ◽

Author(s):

James Sevik ◽

Michael Pamminger ◽

Thomas Wallner ◽

Riccardo Scarcelli ◽

Steven Wooldridge ◽

...

Keyword(s):

Natural Gas ◽

Carbon Dioxide Emissions ◽

Fuel Injection ◽

Direct Injection ◽

Peak Load ◽

Charge Motion ◽

Load Range ◽

Absolute Increase ◽

Efficient Operation ◽

Indicated Mean Effective Pressure

The present paper represents a small piece of an extensive experimental effort investigating the dual-fuel operation of a light-duty spark ignited engine. Natural gas (NG) was directly injected into the cylinder and gasoline was injected into the intake-port. Direct injection of NG was used in order to overcome the power density loss usually experienced with NG port-fuel injection as it allows an injection after intake valve closing. Having two separate fuel systems allows for a continuum of in-cylinder blend levels from pure gasoline to pure NG operation. The huge benefit of gasoline is its availability and energy density, whereas NG allows efficient operation at high load due to improved combustion phasing enabled by its higher knock resistance. Furthermore, using NG allowed a reduction of carbon dioxide emissions across the entire engine map due to the higher hydrogen-to-carbon ratio. Exhaust gas recirculation (EGR) was used to (a) increase efficiency at low and part-load operation and (b) reduce the propensity of knock at higher compression ratios (CR) thereby enabling blend levels with greater amount of gasoline across a wider operating range. Two integral engine parameters, CR and in-cylinder turbulence levels, were varied in order to study their influence on efficiency, emissions and performance over a specific speed and load range. Increasing the CR from 10.5 to 14.5 allowed an absolute increase in indicated thermal efficiency of more than 3% for 75% NG (25% gasoline) operation at 8 bar net indicated mean effective pressure and 2500 RPM. However, as anticipated, the achievable peak load at CR 14.5 with 100% gasoline was greatly reduced due to its lower knock resistance. The in-cylinder turbulence level was varied by means of tumble plates as well as an insert for the NG injector that guides the injection “spray” to augment the tumble motion. The usage of tumble plates showed a significant increase in EGR dilution tolerance for pure gasoline operation, however, no such impact was found for blended operation of gasoline and NG.

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