Condensable and Gaseous Hydrocarbon Emissions and Their Speciation for a Real World SI Car Test

Condensable and gaseous hydrocarbon emissions and speciation of the hydrocarbons have been investigated using a EURO1 emissions compliant SI (Spark Ignition) car. Exhaust gas samples were simultaneously collected upstream and downstream of the catalyst using a system containing cold ice trap, resin, particulate filter block and Teflon gas sampling bag. GC (Gas Chromatography) was employed to analyze for hydrocarbons and 16 of the more significant hydrocarbons are reported. The test was carried out using both cold start and hot start driving cycles.

Results show that the benzene and toluene were major species emitted from the tailpipe under cold start conditions. Methylnaphthalene was a dominated hydrocarbon under hot start conditions. The cold start had significant influence on hydrocarbon emissions. The catalyst out benzene emissions for cold start was thirty times higher than that for hot start. The catalyst out toluene emissions was not detectable for hot start and 0.7 mg/km for cold start conditions. Catalyst efficiencies were also determined for each species. It was found that under cold start condition the catalyst had significant impact on butane, iso-butane, acetylene and methane emissions due to low temperature of the catalyst at cold start.