Advanced diesel fuels simulation in a modern DI diesel engine

摘要

Some results on the performance of a modern Common Rail Dl diesel engine, fed by different blends of an advanced diesel fuel with a high cetane number oxygenated fuel, are presented. The experimental characterisation on the FIAT M724 engine, installed on the Alfa Romeo 156 1.9 JTD, has assessed the great potential of modern diesel engine generation coupled with the fuel reformulation technology adopting synthetic fuels. The base fuel was a reformulated diesel fuel with low aromatic and sulphur content. Two blends with different volumetric percentages (10. and 20%) of Diethylene-Glycol-Dimethyl-Ether (diglyme) in the base fuel were tested. It was confirmed that, also in the case of modern injection systems, the use of diglyme as additive reduces simultaneously HC, CO and soot. On the other hand fuel oxygenation appears not so influencing as relative to NO{sub}x emissions. In fact, in the modern engine management NO{sub}x formation is controlled by the use of relatively high EGR ratio. Combustion simulations were performed with an in-house version of the Kiva3V code. The comparison between experimental and numerical data was made at different engine operating conditions but only one test point (2000 rpm. 2 bar b.m.e.p.) is reported as representative of the engine behaviour in the urban driving schedule of the European test procedure for exhaust emission ranking. Blends of the base fuel with diglyme were simulated. Results from C.F.D, simulations are reported in terms of in-cylinder combustion pressure and soot mass evolution showing an acceptable predictivity of the code. Numerical results, also in terms of in-cylinder soot distribution, confirm that fuel oxygenation with high cetane number products is an efficient way to realise drastic soot emission reduction.