Particulate matter emissions from flex-fuel vehicles with direct fuel injection

Abstract

Otto cycle vehicles with gasoline direct injection (GDI) can reduce fuel consumption by 5–20%. In compliance with current legislation in Brazil, this technology was introduced to the domestic market in the form of a first flex-fuel GDI vehicle in 2013. However, despite gains in efficiency, studies in the literature have shown that GDI engines tend to have higher particulate matter emissions than port fuel injection (PFI) engines. This paper provides measurements of the emissions of GDI flex-fuel vehicles fuelled with gasoline containing 22% anhydrous ethanol (E22), hydrous ethanol (E100) and a 50% mixture of both (E61). The blending fuels were tested in accordance with the recommendations made in the widely known FTP 75 and HWFET cycles. The particulate-matter emissions formed during the combustion process were closely linked to fuel-type properties. The results showed the particles that adhere to sampling filters have higher concentrations of fluorine and carbon and lower amounts of silicon and oxygen, as well as sizes of around 2 μm. The black carbon emissions tend to increase directly with the gasoline content in the fuel. The results also provided evidence that the HWFET test cycle showed a higher emission rate of total particulate matter than the FTP 75 test cycle, and that overall, there were higher emissions for E22 than E100.