Análise do aumento da razão volumétrica de compressão de um motor flexível multicombustível visando melhoria de desempenho

AUTOR(ES)
DATA DE PUBLICAÇÃO

2005

RESUMO

Multifuel spark ignition engines fuelled by gasoline and anhydrous ethanol are highly widespread in Brazilian market. Compressed natural gas is also increasing its marketshare due to the installation of adaptive kits in gasoline-fuelled or anhydrous ethanolfuelled engines. However, those adapted engines do not present the best performance for compressed natural gas because of the low compression ratio of the engines for this fuel. In this work, the performance of a multifuel engine running different compression ratios with gasoline, anhydrous ethanol and compressed natural gas is analyzed, and the development of an optimized flexible engine will be on the basis of the results. With this objective, a development programmable electronic control unit and a 5th generation multipoint compressed natural gas system are installed on the engine. The programmable unit is calibrated for the engine fuelled by gasoline, anhydrous ethanol and compressed natural gas running 11:1, 12,5:1 and 15:1 compression ratios. The modification of the compression ratios was made replacing the set of pistons. Firstly, the results are obtained for gasoline, anhydrous ethanol with the original electronic control unit and 11:1 compression ratio, in order to be a reference on the calibration. Lately, for the compression ratio of 11:1 and 12,5:1, the results for gasoline, anhydrous ethanol and compressed natural gas with the electronic control unit are compared with the original system results. Finally, for the compression ratio of 15:1, the results for anhydrous ethanol and compressed natural gas are analyzed. Fuel injection time maps, ignition advance maps a performance curves are compared for different compression ratios and different fuels. The results present the differences on the engine calibration maps for each fuel. Increasing the compression ratio to 12,5:1 and 15:1 only presented improvements for the engine running with compressed natural gas. Fuelled by gasoline and anhydrous ethanol, the engine performance was reduced. The ethanol and compressed natural gas ignition advance maps show that the ignition advances were reduced, but they are higher than the ignition advance for gasoline with 11:1 compression ratio.

ASSUNTO(S)

motores de combustão interna teses. engenharia mecânica teses.

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