Investigation of Odorous Components and Improvement in Odor Assessment Procedure in DI Diesel Engines 2002-01-2875
This study investigated the odorous components in the exhaust of DI diesel engines. The complete products of combustion are H2O and CO2, which have no odor. Therefore, other products of incomplete combustion like unburned fuel components, partially burned components, cracked products from thermal cracking and others are thought to be responsible for exhaust odor.
The THC in the exhaust is the result of incomplete combustion. This study measured THC in the exhaust, and a good correlation was found between THC and exhaust odor at different engine conditions. The low boiling point hydrocarbon components, especially CH4 in diesel exhaust were found to show a good correlation with exhaust odor.
Aldehydes in exhaust gases correlate with exhaust odor very well and among the aldehydes, formaldehyde is found to be the most important component in causing irritating odor.
The other part of this study is devoted to the improvement in the odor assessment used for DI diesel engines. Usually direct assessment is used in odor assessment. The direct assessment is where the human nose is directly exposed to the gas stream at the manifold or at the tail pipe, and is not capable of checking odors correctly in some types of engine conditions where the time for assessment is short or where there is a great change in the assessed gas speed and temperature. This study developed a new method of indirect assessment to overcome the shortcomings of direct assessment.