Comparação de ciclos de condução padrão aplicados a um veículo de passageiro operando com etanol

Abstract

The forecast scenarios regarding the environmental pollution raises a question whether the current vehicle emission certification is reliable enough to assure fleet agreement with the legal limits. Standardized procedures such as the FTP-75 proposed in the United States (currently incorporated in the Brazilian legislation) and the Worldwide harmonized Light vehicles Test Cycle (WLTC) are discussed in this paper. Both cycles were performed in a chassis dynamometer with the driver, vehicle and fuel kept constant so the comparison between the cycles would not be compromised. The vehicle chosen was a 1.4 dm³ displaced volume FIAT sedan with maximum power of 60 kW at 5500 rpm and maximum torque of 122 Nm at 2250 rpm. The five points estimated as the most representative of both tests were selected for steady-state investigations in terms of fuel consumption and air excess factor and conducted using hydrous-ethanol (E97W03) – ethanol blend available in Brazilian fuel stations. The results showed that the FTP-75 demanded greater average and maximum acceleration values, implying on more aggressive driving conditions. The WLTC presented a more homogeneous acceleration per speed diagram, providing higher average speed and speed standard deviation (i.e., more transient conditions). It could be seen that the WLTC covers a wider range of engine operation conditions holding more dispersed points than the FTP-75. In addition, the WLTC contained points with higher load, which made the results for fuel consumption to be higher compared to FTP-75. The engine operation points provided by the FTP-75 were excessively condensed. Therefore, it could be concluded that the FTP-75 can be a predictable test with repeated points of operation. Also, it could be observed that depending on the test specifications the driver can largely influence the performance of the vehicle.