Effects of a Catalytic Volatile Particle Remover (VPR) on the Particulate Matter Emissions from a Direct Injection Spark Ignition Engine

Abstract

Emissions of fine particles have been shown to have a large impact on the atmospheric environment and human health. Researchers have shown that gasoline engines, especially direct injection spark ignition (DISI) engines, tend to emit large amounts of small size particles compared to diesel engines fitted with diesel particulate filters (DPFs). As a result, the particle number emissions of DISI engines will be restricted by the forthcoming EU6 legislation. The particulate emission level of DISI engines means that they could face some challenges in meeting the EU6 requirement. This paper is an experimental study on the size-resolved particle number emissions from a spray guided DISI engine and the performance of a catalytic volatile particle remover (VPR), as the EU legislation seeks to exclude volatile particles. The performance of the catalytic VPR was evaluated by varying its temperature and the exhaust residence time. The effect of the catalytic VPR acting as an oxidation catalyst on particle emissions was also tested. The results show that the catalytic VPR led to a marked reduction in the number of particles, especially the smaller size (nucleation mode) particles. The catalytic VPR is essentially an oxidation catalyst, and when post three-way catalyst (TWC) exhaust was introduced to the catalytic VPR, the performance of the catalytic VPR was not affected much by the use of additional air, i.e., no significant oxidation of the PM was observed.

Physical, chemical, and toxicological characteristics of particulate emissions from current technology gasoline direct injection vehicles

“…Gasoline direct injection (GDI) vehicles are on the rise and are receiving increased attention by automotive manufacturers because of their improved fuel economy and hence lower greenhouse gas (GHG) emissions compared to their port-fuel injection (PFI) counterparts (Xu et al, 2011). GDI engines combined with turbocharging and lightweighting technologies are one of the very few viable engine platforms to meet the Corporate Average Fuel Economy (CAFE) standards that have specified fuel economy to exceed 55 miles/gal (4.2 L/100 km) in passenger cars by 2025.…”

Influence of Mileage Accumulation on the Particle Mass and Number Emissions of Two Gasoline Direct Injection Vehicles

“…But it similarly faces technical challenges to meet future PM emissions standards. 4,5 This technology has evolved considerably over the past decade and half, and is still undergoing development. Early versions of direct injection employed a stratified injection strategy which included late fuel injection and charge air motion to produce a stoichiometric air/fuel mixture in the vicinity of the spark plug and, thereby, avoid pumping losses from the need to throttle the engine at light load.…”

“…GDI is a strategy to improve fuel efficiency that can relatively easily replace existing port fuel injected (PFI) engines, and is already seeing widespread availability. But it similarly faces technical challenges to meet future PM emissions standards. , This technology has evolved considerably over the past decade and half, and is still undergoing development. Early versions of direct injection employed a stratified injection strategy which included late fuel injection and charge air motion to produce a stoichiometric air/fuel mixture in the vicinity of the spark plug and, thereby, avoid pumping losses from the need to throttle the engine at light load. , The drawback is that direct injection of fuel into the combustion cylinder risks liquid fuel impingement onto the piston and cylinder surfaces and inhomogeneous air fuel mixing; consequentially PM formation is higher than in conventional PFI gasoline engines. , This is difficult to avoid during late injection as the piston approaches the top of its stroke, therefore more recent development of GDI technology has focused on early injection, or so-called homogeneous operation. , …”