Sub-23 nm Particulate Emissions from a Highly Boosted GDI Engine

Abstract

Downsized, highly boosted, GDI engines are becoming the preferred gasoline engine technology to ensure that increasingly stringent fuel economy and emissions legislation are met. The Ultraboost project engine is a 2.0 L in-line 4-cylinder prototype engine, designed to have the same performance as a 5.0 L V8 naturally aspirated engine but with reduced fuel consumption. It is important to examine Particle Number (PN) emissions from such extremely highly boosted engines to ensure that they are capable of meeting current and future emissions legislation. The effect of such high boosting on PN emissions is reported in this paper for a variety of operating points and engine operating parameters. The effect of engine load, air fuel ratio, fuel injection pressure, fuel injection timing, ignition timing, inlet air temperature, EGR level, and exhaust back pressure have all been investigated. It is shown that PN emissions increase with increases in cooled, external EGR and engine load, and decrease with increases in fuel injection pressure and inlet air temperature. PN emissions are shown to fall with increased exhaust back pressure, a key parameter for highly boosted engines. The effects of these parameters on the particle size distributions from the engine have also been evaluated. Significant changes to the particle size spectrum emitted from the engine are seen depending on the engine operating point. Operating points with a bias towards very small particle sizes were noted.

The effect of oxygenate fuels on PN emissions from a highly boosted GDI engine

“…The results from this DMS using this sampling methodology have been shown to represent the legislatively compliant European PMP test procedure results closely [37]. The sampling and analysis methods used with the DMS in this work have been comprehensively described in [5] but are summarized here for convenience. Due to the very small accumulation mode particles observed, simply using the standard DMS fitting software was not a reliable method.…”

“…The particle mass contribution is dominated by the accumulation mode, with the nucleation mode having a minor effect on the mass emitted, as the largest particles have the highest mass. Such emissions have been well characterized [4], but only recently from GDI engines operating at high levels of boost [5].…”

Simulation of deep-bed filtration of a gasoline particulate filter with inhomogeneous wall structure under different particle size distributions

“…Chasapidis et al 17 developed a sampling and conditioning particle system designed for the measurement of sub-23 nm solid particles. The literature 18 suggests that PN emissions from GDI engines might increase 35%–50% by moving D50 to 10 nm. The stricter PM and PN limits of particulate emissions will bring broader application to GPFs, which are an inevitable choice for GDI engines that comply with the future regulations.…”

A case study on particulate emissions from a gasoline plug-in hybrid electric vehicle during engine warm-up, taking into account start–stop operation

“…25 In the meantime, numerous other studies show an existing and steadily increasing interest in these smallest particles, which can be emitted by vehicles with a GDI. 26–28…”

“…25 In the meantime, numerous other studies show an existing and steadily increasing interest in these smallest particles, which can be emitted by vehicles with a GDI. [26][27][28] As a result of the global emission regulations, hybridized electric vehicles (HEV), which combine a conventional internal combustion engine (ICE) and an electric machine (EM) with its corresponding energy storage systems (e.g. lithium-ion batteries), are expected to soon play a major role in the market.…”