The Analysis of Gasoline Transient Emissions Behaviour Using Fast Response Gas Analysers

For domestically produced passenger car gasoline fuelled vehicles, the forthcoming task of emissions compliance in India (Bharat-IV by 2010) may require a more detailed knowledge of transient engine behaviour by Indian engineers. Under steady state conditions and with reasonable fuel preparation, three-way catalytic converters can remove around 98% of legislated pollutants. However, during cold start and gear changes, the transient emissions are not fully converted by the catalyst; the cold start alone contributing typically 90% of the total Cycle Hydrocarbon (HC) emissions for the Euro- IV drive cycle [1].

This paper presents data measured pre and post the three-way catalyst on a EURO- III compliant European manufactured production Port-Fuel-Injection (PFI) gasoline engine running on a FTP drive cycle. The transient emissions were measured using fast response gas analyzers, with time response giving resolution at better than engine firing frequency. The paper examines in some detail, the different unsteady phenomena which produce significant emissions and demonstrates how such advanced instrumentation could be used to identify and subsequently improve emissions. It is concluded that transient emissions data will be a significant aid to meeting current and future emissions legislation.