A Study of Gasoline-Ethanol Blends Influence on Performance and Exhaust Emissions from a Light-Duty Gasoline Engine

摘要

This paper evaluates the possibility of using bioethanol blends (mixtures of gasoline fuel and ethanol derived from biomass) of varying strengths in an unmodified, small-displacement European Euro 5 light-duty gasoline vehicle. The influence of different proportions of bioethanol in the fuel blend (E5, E10, E25, E50 and E85) on the emission of gaseous pollutants, such as: carbon monoxide, hydrocarbons, oxides of nitrogen and carbon dioxide was tested at normal (22°C) and low (-7°C) ambient temperatures for a light-duty vehicle during the NEDC cycle on a chassis dynamometer. Engine performance metrics were also tested. All test results are presented in comparison to standard European gasoline (E5). Tailpipe emission data presented here suggest that modest improvements in air quality could result from usage of low-to-mid ethanol blends in the vehicle tested. In general, blends up to and including E50 were relatively unproblematic; emissions of regulated compounds and CO_2 were in some cases substantially lower for ethanol blends higher than E5 (standard European gasoline). This finding has potentially significant implications for air quality scenarios regarding potential greater usage of ethanol blends. However, the usage of two ambient temperatures in this study confirmed previous findings that such emissions reductions are in some cases strongly temperature dependent, and further testing is required in this area. Overall, no single blend emerged as a clear best or worst performer at either test temperature. Although maximum engine power and torque values for all blends were very similar, it was observed that for the E5 blend, engine power and torque were the highest, whereas for the blend E10 they were the lowest. The maximum power for the blend E10 was some 2% lower (significant at the 95% confidence level) in comparison to results obtained for the E5 blend. This paper represents a continuation of related research previously described elsewhere.