Particulate Formation in Gasoline Direct Injection Engines
This work presents experimental investigation of particulate emissions from a naturally aspirated single cylinder metal gasoline engine operated in a homogeneous configuration. The engine was modified to be capable of operating using DI, PFI, or both simultaneously. PFI was configured with a custom inlet manifold to inject about 50 cm upstream of cylinder head, forming a more homogeneous fuel-air mixture than would otherwise be possible. The experimental campaigns were structured to systematically isolate and study different PN formation mechanisms. Mixing quality was improved ubstantially by using a small amount of upstream injection together with direct injection and could be controlled by varying the mass split between the direct and upstream injectors. It was found that using a small upstream injection when operating in GDI mode could reduce PN emissions by up to a factor of 10 while only modestly increasing fuel consumption.
The chemical composition of the fuel could also strongly affect particulate emissions. Therefore, to find alternative ways of reducing PN emissions, experiments were conducted using a gasoline engine with fuel blends containing renewable oxygenates – either 10% (v/v) ethanol (EtOH) or 22% (v/v) ethyl tert-butyl ether (ETBE). It was observed that PN emissions was reduced using oxygenated fuels at low load for both PFI and DI operation, but not at higher loads where PN increased instead. Measurements of solid PN (SPN) emissions revealed that more soot was formed at high load along with an increase in emissions of volatile organic compounds (VOC).
PN measurements were conducted using a DMS500 fast particle spectrometer supplied by Cambustion. In addition, solid particulate measurements were performed by passing exhaust samples through a thermodenuder and a catalyst to remove most of the volatile organic compounds (VOCs) from the raw emissions. The results indicated that wall-wetting is the dominant particulate formation mechanism inside the cylinder: fuel-wall interactions with the piston, cylinder walls, and valves during the fuel injection period account for a significant fraction of the PN content of raw exhaust.
Gasoline Direct Injection
Förbränningsmotorer och framdrivningssystem
Particulate Emissions in a GDI with an Upstream Fuel Source
SAE Technical Papers,; Vol. 2019-01(2019)
Paper i proceeding
Etikyala, S., Sharma, N., Sjöblom. J., Karvo. A., Keskiväli. J., Kolehmainen.T., Koopmans, L., & Dahlander, P. "Particulate Emissions from GDI Engines fueled with Gasoline and Renewable Fuel Blends", submitted to Fuel Journal Elsevier
Innovation och entreprenörskap
Chalmers tekniska högskola
Gamma/Delta, Hörsalsvägen 7A
Opponent: Dr. Valery Chernoray, Chalmers, Sweden