Oxygenated Fuels for Particulate Emissions Reduction in Heavy-Duty DI-Diesel Engines with Common-Rail Fuel Injection 2000-01-2885
Oxygenated fuel additives are currently an important research topic for particulate emissions reduction in diesel engines with direct injection (DI) to meet future emission regulations.
In this work more than twenty oxygenated hydrocarbons from the literature were considered as diesel fuel additives. Butylal (an acetal compound, chemical formula C9H20O2) offers significant advantages over most other oxygenates in that its physical properties are very close to those of common diesel fuel.
Wear scar measurements were conducted to evaluate the lubricity characteristics of diglyme (C6H14O3), ethyldiglyme (C8H18O3), butylal and different diesel-butylal mixtures. The results reveal the low lubricity of all oxygenated compounds. Thus, for the engine tests, a lubricity improver has been added to the diesel-butylal mixtures.
Preliminary results from experiments performed on a single-cylinder research engine with a displacement of 2 liters and common-rail injection indicate that:
Butylal substantially lowers the exhaust gas opacity.
The opacity reduction with butylal mixtures depends on the combustion process conditions and the injection parameters, mainly on the injection pressure.
Butylal lowers the premix combustion rate and the combustion noise due to its high cetane number.
At constant injected fuel mass flow rate, the NOx emissions are not affected from the addition of butylal in diesel fuel.
Butylal is therefore a promising additive for an improvement in the NOx versus PM trade-off for DI-diesel engines.