Emissions, fuel economy and energy consumption of a flex fuel vehicle in different driving cycles

摘要

Brazilian INOVAR-Auto program - the first vehicle fuel efficiency legislation held from 2013 to 2017 - encouraged improvements in vehicles energy efficiency with a significant reduction in the intensity of carbon emissions from passenger cars and light duty vehicles by the end of 2017: a minimum of 12% of fuel energy consumption in MJ/km with the corresponding emissions reduction of CO_2 in g/km, in comparison to 2012. An amendment to this program offered a specific tax rebate incentive for automakers whose Flex Fuel Vehicles (FFVs) met the Hydrous Ethanol (E100)/Gasohol (E22) fuel economy ratio above 0.75, without degrading gasoline consumption. Interesting to note that no FFV has been able to meet this criteria up to now. The new vehicle fuel efficiency legislation, currently under discussion and approval (ROTA 2030), considers now a less aggressive target of E100/E22 FE ratio for the tax benefit: 0.693, with an increasing proportional benefit for higher FE ratios. The incentive aims the development of technologies to improve the efficiency of Flex-fuel engines when using E100, which significantly contributes to the reduction of greenhouse gas (GHG) emissions. Other strategic factors for the local interest in higher E100 efficiency are the clean and sustainable solution for an increasing fuel demanding market by 2030 and the maintenance of local infrastructure of ethanol production, technological centers and installed automotive capacity. Stimulating higher E100 efficiency might allow a smoother transition to the full electric vehicle. A recent analysis of specific fuel consumption of a FFV engine demonstrates that there are working regions where E100/E22 FE ratio reaches 0.77. However, these regions are not reached when the vehicle is tested according to the ABNT NBR 6601 driving cycle. This fact motivated then a comparative review of current driving cycles of Brazilian fuel consumption and emissions regulations with other available regulations. This article aims to explore the differences between the driving cycles in Brazilian regulations compared to North American and European ones, which have among other characteristics complementary driving cycles that provide greater representativeness of real use conditions in external routes. It highlights the differences between gasohol (E22) and hydrous ethanol (E100) fuels regarding emissions and fuel economy in a normal production vehicle, tested in standard vehicle laboratory conditions according to these regulations and at real life using PEMS (Portable Emissions Measurement System) according to Euro 6D regulation. A practical method to evaluate the energy consumption (in MJ/km) and vehicle efficiency has been implemented in order to compare and analyze the results of different driving styles.