Efeitos da razão volumétrica de compressão e do tipo de combustível na combustão, eficiência e emissões de um motor com injeção direta

Abstract

In this work, experimental results for a single cylinder research engine with compression ratios of 11.5:1 and 15:1 with direct injection of E22 (emissions standard Brazilian gasoline) and E100 (hydrous ethanol) are presented to evaluate the effects of compression ratio and fuel on combustion, efficiency and emissions. These experiments were made in an intermediate point of the engine operation range with speed of 2000 RPM and indicated mean effective pressure of 4 bar. Computational fluid dynamics simulations were conducted for the same operation conditions to validate an engine simulation methodology for direct injection engines. When analyzing fuel effects, an increase of efficiency of 2.7% and 2.0% were obtained using E100 compared to E22 for compression ratios of 11.5:1 and 15:1, respectively. When comparing E100 and E22 a specific emissions reductions of CO2 of 4.0% and 4.6%, of NOx of 42.9% and 50.9% and of unburned hydrocarbons of 17.9% and 28.0% were observed for compression ratio of 11.5:1 and 15:1 respectively. The compression ratio effect on efficiency resulted in an increase of 0.9% and 1.6% when using the compression ratio of 15:1 compared to compression ratio of 11.5:1 for E100 and E22, respectively. When comparing the compression ratios of 15:1 and 11.5:1 and a specific emissions reductions of CO2 of 7.6% and 7.0% and specific emissions increase of CO of 93.4% e 17.0% and unburned hydrocarbons of 56.5% and 78.6% were observed for ethanol and gasoline, respectively. When comparing gasoline with compression ratio of 11.5:1 with ethanol with compression ratio of 15:1 the biggest gain in efficiency was observed with a 3.6% increase. The numerical methodology was validated for these same cases and showed differences smaller than 6% in the indicated mean effective pressure for all cases.