Abstract
This study examines the effects of ethanol and gasoline injection mode on the combustion performance and exhaust emissions of a twin cylinder port fuel injection (PFI) spark ignition (SI) engine. Generally, when using gasoline–ethanol blends, alcohol and gasoline are externally mixed with a specified blending ratio. In this activity, ethanol and gasoline were supplied into the intake manifold into two different ways: through two separated low pressure fuel injection systems (Dual-Fuel, DF) and in a blend (mix). The ratio between ethanol and gasoline was fixed at 0.85 by volume (E85). The initial reference conditions were set running the engine with full gasoline at the knock limited spark advance boundary, according to the standard engine calibration. Then E85 was injected and a spark timing sweep was carried out at rich, stoichiometric, and lean conditions. Engine performance and gaseous and particle exhaust emissions were measured. Adding ethanol could remove over-fueling with an increase in thermal efficiency without engine load penalties. Both ethanol and charge leaning resulted in a lowering of CO, HC, and PN emissions. DF injection promoted a faster evaporation of gasoline than in blend, shortening the combustion duration with a slight increase in THC and PN emissions compared to the mix mode.
Highlights
Ethanol can be considered a proper alternative fuel for spark ignition (SI) engines because it shows several physical and combustion properties similar to gasoline and it can be produced from renewable energy sources
DF injection promoted a faster evaporation of gasoline than in blend, shortening the combustion duration with a slight increase in THC and particles number (PN) emissions compared to the mix mode
Ethanol-gasoline blends were extensively studied in engine research [3,4], the results showed that ethanol-gasoline blended fuels provide higher engine efficiency, compared to neat gasoline
Summary
Ethanol can be considered a proper alternative fuel for spark ignition (SI) engines because it shows several physical and combustion properties similar to gasoline and it can be produced from renewable energy sources. Some researchers showed that PM emissions from DI engines can either increase or decrease with ethanol content depending on fuel injection timing [11] This result indicates that engine-out particles emissions from ethanol-blended gasoline are still not nearly as well understood as those for diesel or gasoline [12]. Even if the particle formation could be influenced by mixture formation, at the present time, no studies have been carried out on the influence of the injection strategy (port dual fuel and single injection) on particle emission The purpose of this investigation is to assess the effects of ethanol-gasoline injection mode on performance and exhaust emissions of a downsized PFI twin-cylinder turbocharged engine.
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