Effect of MTBE and DME on Odorous Emissions in a DI Diesel Engine

MTBE (Methyl Tertiary Butyl Ether) blended diesel fuel, and DME (Dimethyl Ether) with the homogeneous charge compression ignition (HCCI) system are very attractive for NOx and PM (particulate matters) reductions in DI diesel engines, while their effects on combustion and odorous emissions are not clear. In this study, a few percent MTBE blended in diesel fuel gives a lower HCHO (formaldehyde) and an improved exhaust odor than with neat diesel fuel, while over 10% blend, a very low boiling point MTBE forms an overlean mixture and diminishes the positive effect of the O2 content of MTBE. The study of DME achieved a 100% DME combustion, and hybrid combustion of DME and diesel fuel with HCCI system. Two peaks in heat release during combustion appear in DME and hybrid-operation under an ultra-lean engine operation. Although the homogeneous DME mixture allows the ultra-lean engine operation, It also gives a very strong exhaust odor together with higher HCHO and THC (total hydrocarbon).