Effects of commercial ethanol-blended gasoline on emissions of a blended plug-in hybrid electric vehicle

Plug-in hybrid electric vehicles (PHEVs) are a promising approach to reduce fuel consumption and carbon emissions but still face challenges in pollutant emission performance. Ethanol as a carbon-neutral fuel has been widely added to commercial gasoline and has the potential to reduce emissions. The objective of this study is to determine the effect of ethanol-blended gasoline on PHEV emissions. Firstly, a blended PHEV fueled with neat gasoline was tested over the worldwide harmonized light-duty vehicle test cycle. Enormous emissions of PN and NOx were observed, attributed to the high-power cold starts (HPCSs) and oxygen storage saturation in the threeway catalyst converter. Secondly, a cycle was designed to investigate the effect of coolant temperature on particle number (PN) emissions during HPCSs. In the designed cycle, three fuels with different ethanol fractions (0%, 10%, and 20% v/v), named E0, E10, and E20, were tested. It was found that both E10 and E20 could reduce PN emissions during HPCSs. The reduction at the coolant temperature of about 20 degrees C was marginal but became significant at the coolant temperature above 30 degrees C. Both E10 and E20 increased the NOx emissions during the HPCS and oxygen storage saturation. Based on the results, suggestions for reducing PN and NOx emissions of the PHEV fueled with ethanol-blended gasoline were provided.