Effect of Ignition Delay and Exhaust Gas Speed on Exhaust Odor in DI Diesel Engines

This study investigated the effect of ignition delay and exhaust gas speed on exhaust odor in DI diesel engines. From the investigation of many engine parameters like injection timing and injection pressure, it has been found that the optimum ignition start position is more important than the shorter ignition delay, but the optimum ignition start position along with the shorter ignition delay is the best scenario for minimum odor. Further, it has been found that good mixture formation is more important than shorter ignition delay in reducing odor, but the optimum mixture formation together with shorter ignition delay results in the lowest odorous emissions. From the investigation of various fuels in the diesel engine, it seems that the combustion pattern and the raw odor of fuel are more important than ignition delay. A fuel with low raw odor and high cetane number with optimum boiling point significantly improves the exhaust odor.

Exhaust gas speed is found to have a strong influence on odor sensation. The higher the gas speed, the higher the resulting exhaust odor seems to be for gases of similar odorous concentrations. Also the gases with higher odorous concentrations show lower exhaust odor in lower gas speed condition. The combination of lower odor-causing emissions concentrations, with low exhaust gas speed is favorable for the odor reduction.