Analysis of Surrogate Fuels Effect on Ignition Delay and Low Temperature Reaction during Partially Premixed Combustion
Fuel effects on ignition delay and low temperature reactions (LTR) during partially premixed combustion (PPC) were analyzed using Design of Experiments (DoE). The test matrix included seventeen mixtures of n-heptane, isooctane, toluene and ethanol covering a broad range of ignition quality and fuel chemistry. Experiments were performed on a light-duty diesel engine at 8 bar IMEPg, 1500 rpm with a variation in combustion phasing, inlet oxygen concentration and injection pressure. A single injection strategy was used and the start of injection and injection duration were adjusted to achieve the desired load and combustion phasing. The experimental data show that fuels with higher Research Octane Number (RON) values generally produced longer ignition delays. In addition, the alcohol content had significantly stronger effect on ignition delay than the aromatic content.