September 29, 2017
“Gasoline Particulate Filters” – a paper by W. Addy Majewski published September 5, 2017 on DieselNet – discusses an emerging aftertreatment technology.
Gasoline particulate filters (GPF) are an emission aftertreatment technology based on diesel particulate filters (DPF), developed to control particulate emissions from gasoline direct injection (GDI) engines. The population of GDI vehicles has been increasing, driven by CO2 and/or fuel economy requirements.
In 2016, an estimated 2/3 of new gasoline cars in Europe were GDI. The proportion of GDI vehicles has been also rapidly increasing in North America—within nine years after its first significant use in the market, GDI penetration has climbed to 48.5% of new light vehicle sales in the United States. Emissions from the growing GDI vehicle fleet are a public health concern and a potential major source of ambient particle pollution in highly populated urban areas.
GPFs are expected to be used primarily in the European Union and in China, to meet the particle number (PN) emission standards for GDI vehicles—passenger cars and light commercial vehicles—adopted in both jurisdictions. The Euro 6 and China 6 regulations set PN (as well as PM) limits for GDI vehicles that are equivalent to those for diesels. The European PN standards, both effective for new types of GDI cars from September 2017, are:
- A PN limit of 6.0×1011 km-1 over the NEDC / WLTC test cycle (Euro 6c)
- RDE testing for PN emissions with a conformity factor of 1.5, i.e., PNRDE = 9.0×1011 km-1 (Euro 6d-TEMP)
The above standards could also be met—at least in certain types of vehicles—via in-cylinder controls such as fuel injection strategies, without particulate filters. However, the GPF has several advantages compared to in-cylinder controls:
- Effectiveness under all operating conditions—While in-cylinder strategies tend to be more effective under certain modes of operation, the GPF provides PN emission control under all engine operating conditions—an advantage that is especially important in RDE testing.
- Control of emissions from engine faults—Increased PN emissions can occur as a result of engine faults and malfunction, such as increased lube oil consumption. These emissions can be effectively controlled by particulate filters.
- Control of unregulated emissions—The GPF can control certain unregulated emissions, including polynuclear aromatic hydrocarbons (PAH). GDI engines, even though equipped with three-way catalysts (TWC), may produce significant levels of toxic PAH emissions.
Most early GPF applications include an uncoated GPF positioned downstream of a three way converter catalyst . As the technology matures, GPFs may be coated with a three-way catalyst. This catalyst coated GPF configuration is sometimes referred to as the 4-way catalyst
What this means to you
Gasoline particulate filters (GPF) are an emission aftertreatment technology based on diesel particulate filters (DPF), developed to control particulate emissions from gasoline direct injection (GDI) engines.
MIRATECH can help
Contact MIRATECH to learn more about stationary engine emission controls.