| Popis: |
The increasing concerns of greenhouse gases and deprived air quality have compelled researchers and vehicle manufacturers to investigate more efficient vehicle powertrains. Gasoline direct injection (GDI) engines, as opposed to previous spark ignited technologies are capable of reducing fuel consumption, and therefore CO₂ emissions. However, the main drawback is the increased level of particulate matter (PM) emissions due to the more heterogeneous mixture formation in GDI engines. Therefore, upcoming emission standards will include gasoline engines in PM legislation. The aim of this investigation is to characterise PM (size, shape and composition), as the lung deposition rate, atmospheric residence time and soot oxidation patterns are highly dependent on PM characteristics. Understanding these properties will also aid in the design of more efficient aftertreatment devices targeting the specific features of PM present in GDI exhausts. In this work, on-board reforming has been used to generate a rich-in-hydrogen gas. Hydrogen combustion has been observed to reduce particle number concentration significantly without affecting the oxidation behaviour or the nanostructure properties of the soot whilst reducing CO₂ emissions. In addition to this, the performance of gasoline particulate filters has been assessed as well as the role of the three way catalyst in PM reduction. |
