Gasoline Evaporative Emissions - Ethanol Effects on Vapor Control Canister Sorbent Performance

Tests were performed at the University of North Dakota Energy & Environmental Research Center (EERC) to compare the evaporation rate of 10 volume percent ethanol-blended gasoline (E10) with the evaporation rate of its base gasoline. Averaged results of the tests demonstrated that at 70°F (21.1 °C), the E10 fuel lost more total weight to evaporation than its base fuel, but less gasoline. The increased weight was due to ethanol, which was present in the E10 evaporative emissions at concentrations of about 13 weight percent. Subsequently, a test system was designed to investigate how the presence of ethanol in the evaporative emission affects the fuel evaporation canister sorbent performance. The system is equipped with a Fourier transform infrared spectrometer (FT-IR) to monitor sorbent breakthrough emission concentrations and compound types. Preliminary data obtained using sorbent from commercial canisters have shown that ethanol vapor breakthrough occurs significantly later than gasoline hydrocarbon vapor breakthrough.