SCANIA 6 cylinder, dualfuelled, turbocharged HCCI engine

1
Sources of CO emissions and the Effects of Octane
number in an HCCI Engine
S. S. Ahmed, F. Mauss Division of Combustion
Physics Lund Institute of Technology
A. Bhave, M. Kraft Department of Chemical
Engineering University of Cambridge
L. Montorsi Department of Mechanical
Engineering University of Modena and Reggio Emilia
Summary We investigate the factors which
influence a reliable prediction of CO emissions
in a dual-fuelled HCCI engine using a stochastic
reactor model (SRM) based engine cycle model.
Furthermore, the role of octane number in
controlling HCCI combustion and emissions is
studied. The model offers a reliable prediction
of combustion parameters, and CO, HC and NOx
emissions.

• SCANIA 6 cylinder, dual-fuelled, turbocharged
  HCCI engine

• Full cycle simulation SRM 1- D finite
  difference code
• Detailed kinetic mechanism iso-octane and
  n-heptane (S 157, R 1552)
• Turbulent mixing Coalescence dispersion model
• Stochastic convective heat transfer model

• Base case validation

• Effect of octane number

• CO emissions

• Mixing of cold and hot fluid parcels
• Convective heat loss to the cylinder wall
• Wall temperature

Reduction in octane number triggers the low
temperature heat release, in turn advancing the
high temperature auto-ignition.
Reliable prediction of auto-ignition timing,
in-cylinder pressure, CO, HC and NOx emissions.
Auto-ignition very sensitive to temperature
fluctuations during compression.

• References
• Bhave, A., Kraft, M., Montorsi, L. and Mauss,
  F., SAE Paper 2004-01-0561.
• Kraft, M., Maigaard, P., Mauss, F., Christensen,
  M., and Johansson, B. (2000) Proc. Combust.
  Inst., Vol. 28, 1195-1201.
• Olsson, J., Erlandsson, O. and Johansson, B.,
  SAE paper 2000-01-2867.

Acknowledgements Financial support from Centre
for Scientific Enterprise Ltd., Cambridge
Commonwealth Trust and EPSRC is gratefully
acknowledged.