Base designspecifications for the single-cylinder research engineare shown in Table 2.To obtain good air utilization, it was desirable toposition the fuel injector near the center of thechamber such that the spray would distribute itselfmore evenly in the cylinderical geometry.
The cooling by thefuel evaporation results in lower fuel-air mixturetemperature near TDC, thereby reducing the engine’sknocking tendency.The assumption that the fuel of the DISI engine isevaporated mainly by absorbing thermal energy fromthe air has been verified by other studies ofexperimentation [20] and 3-D numerical simulation[21].
However, the fact thatall part load data show a small DI fuel consumptionbenefit and the model indicates a similar level isstrong evidence that the difference exists.SUMMARY AND CONCLUSIONSAn approach for the design and development of aresearch single-cylinder direct-injection, spark-ignitioncombustion system is presented.
Nitrogen oxide emissionsare shown to be less than the base PI engine as aresult of charge cooling and the higher residualcontent of the system offsetting the effects of theincreased compression ratio.ACKNOWLEDGEMENTSThe authors recognize Mr. Paul Sleeman foroperating the test cell.
4, 360-64, 1931[20] Salters, D., Williams, P., Greig, A., and Brehob,D., “Fuel spray characterization within anoptically accessed gasoline direct injectionengine using a CCD imaging system,” SAEPaper 961149, 1996[21] Han, L, Reitz, R.D., Claybaker, P.J., Rutland,C.J., Yang, J. and Anderson, R.W.