Particulate Formation in GDI Engines
Doctoral thesis, 2022
emissions from GDI engines over a certification cycle. The mechanisms of PN formation during these stages must therefore be understood to identify solutions that reduce overall PN emissions in order to comply with increasingly strict emissions standards.
This work presents experimental studies on particulate emissions from a naturally aspirated single cylinder metal gasoline engine run in a homogeneous configuration. The engine was adapted to enable operation in both DI and PFI modes. In PFI mode, injection was performed through a custom inlet manifold about 50 cm from the cylinder head to maximize the homogeneity of the fuel-air mixture. The metal head was eventually modified by incorporating an endoscope that made it possible to visualize the combustion process inside the cylinder. The experimental campaigns were structured to systematically isolate and clarify PN formation mechanisms. Tests were initially performed in steady state mode to obtain preliminary insights and to screen operating conditions before conducting transient tests. Particulate emissions were measured and correlated with the
images obtained through endoscope visualization where possible.
Key objectives of these studies were to find ways of reducing PN formation by increasing combustion stability. It was found that by avoiding conditions that cause wall wetting with liquid fuel, PN emissions can be substantially reduced during both steady state operation and transients. Warming the coolant and injecting fuel at later timings reduced PN emissions during warmup and cold transient conditions. Additionally, experiments using fuel blends with different oxygenate contents showed that the chemical composition of the fuel strongly influences particulate formation under steady state and transient conditions, and that this effect is load-dependent.
Overall, the results obtained in this work indicate that wall wetting is the dominant cause of particulate formation inside the cylinder and that fuel-wall interactions involving the piston, cylinder walls, and valves during fuel injection account for a significant proportion of PN emissions in the engine raw exhaust.
PM
Alternate fuels
Gasoline Direct Injection
internal combustion engines
Particulate Number
Load transients
Author
Sreelekha Etikyala
Chalmers, Mechanics and Maritime Sciences (M2), Combustion and Propulsion Systems
Visualization of soot formation in load transients during GDI engine warm-up
International Journal of Engine Research,;Vol. 24(2023)p. 3073-3084
Journal article
Particulates in a GDI Engine and Their Relation to Wall-Film and Mixing Quality
SAE Technical Papers,;(2022)
Paper in proceeding
Particulates from a CNG DI SI Engine during Warm-Up
SAE Technical Papers,;Vol. 2021(2021)
Paper in proceeding
Soot Sources in Warm-Up Conditions in a GDI Engine
SAE Technical Papers,;Vol. 2021(2021)
Paper in proceeding
History Effect on Particulate Emissions in a Gasoline Direct Injection Engine
SAE International Journal of Engines,;Vol. 15(2021)
Journal article
Effect of Renewable Fuel Blends on PN and SPN Emissions in a GDI Engine
SAE Technical Papers,;(2020)
Journal article
Particulate Emissions in a GDI with an Upstream Fuel Source
SAE Technical Papers,;Vol. 2019-April(2019)
Journal article
These properties distinguish gasoline direct injection (GDI) engines run with renewable fuels (without any infrastructure changes), from all other efforts towards sustainable transportation. Certainly, there are disadvantages with solely depending on liquid fuel combustion that cannot be ignored when it comes to public health and climate goals, especially particulate emissions. Most recent technical advances in electrification will benefit the world and public health by getting rid of tail-pipe emissions. While the complete transition to electric drive is underway, this thesis aims to provide knowledge on how GDI engines can wield the power to stay relevant and efficient in the coming decade by employing sustainable solutions that profoundly reduce particulate emissions.
This thesis investigates the potential in studying soot formation at a fundamental level through images and experiments that provide adequate resources to formulate data-driven control strategies for reduction of particulate number (PN) emissions. This research also focusses on how such data- driven solutions translates to GDI engines run with fuel blends, multiple injection strategies and even renewable fuels like E85. The conclusion is that in a field that changes as rapidly as transportation, GDI engines have the potential to serve the purpose of easy transportation with almost zero emissions with certain control strategies in the coming years. Nonetheless, this thesis aims to be a delta contribution to reducing the crisis of transportation related environmental and public health damage.
Subject Categories
Mechanical Engineering
Other Mechanical Engineering
Applied Mechanics
Energy Engineering
Fluid Mechanics and Acoustics
Driving Forces
Sustainable development
Areas of Advance
Transport
Energy
Roots
Basic sciences
ISBN
978-91-7905-745-9
Doktorsavhandlingar vid Chalmers tekniska högskola. Ny serie: 5211
Publisher
Chalmers
EB, lecture hall, EDIT trappa C, D och H, Campus Johanneberg .
Opponent: Andre Boehman, professor, University of Michigan, USA