Search Results

The properties of diesel fuels were investigated in terms of particulate emissions to clarify the specification of such a diesel fuel for minimizing particulate emissions. Diesel fuels were analyzed using thin layer chromatography (TLC), and gas chromatography/mass spectrometry (GC/MS). These analysis revealed the entire composition of hydrocarbons in diesel fuels according to molecular formula. The entire composition of hydrocarbons in diesel fuels could be expressd on a three-dimensional graph: the X-axis as carbon number, the Y-axis as H/C ratio and the Z-axis as the amount of hydrocarbons of identical molecular formula. By using the graph, the properties reported so far were investigated. Also, simplified images of the fuel sprayed into a cylinder and its flame were derived from the observational results previously reported.

The effects of diesel fuel properties (aromatic content, cetane index and T90), cetane improver, oxygenates, high boiling point hydrocarbons and aromatics distribution on diesel exhaust emissions were studied under the Japanese 10-15 test cycle and the ECE+EUDC test cycle. The test vehicle was a TOYOTA COROLLA with a natural aspirated, 2.0L displacement, IDI diesel engine. It was demonstrated that particulate emissions are highly correlated with T90 and that NOx is affected by the aromatic content of fuel. A reduction in particulates emissions was observed in fuel with a lower cetane number by adding cetane improver, but this reduction was limited. Cetane improver had no effect on NOx emissions in the 45 # 60 cetane number range. Oxygenates reduced particulate emissions remarkably but had little effect on NOx emissions. A decrease in the soot in particulates was particularly observed.

The effects of methanol/cosolvent/gasoline blends on hot weather driveability are surveyed. Results show that startability after engine-off soak drastically deteriorates in an EFI vehicle. By observing the behavior of the fuel in the delivery pipe during hot-start testing and the injected fuel spray shape at high fuel temperature, the authors confirmed that the main cause of this malfunction was the vapor lock in the injector nozzle. The relationship between hot weather driveability and fuel properties is discussed. The gasoline volatility expression commonly used to indicate deterioration in hot weather driveability was found to underestimate the increase in volatility of blended fuels at higher temperatures. A suggestion is made for a modification to the expression to include the effects of methanol blending on volatility characteristics at high temperatures so that EFI vehicle hot-startability may be predicted.