Abstract
Simultaneous reduction of smoke and NOx from diesel engines with ultra-high EGR (exhaust gas recirculation) is attributed to the lowered combustion temperature and the improved fuel-air mixing by the extended ignition delay. To independently analyze the two effects,the effects of various cetane number fuels on ultra-high EGR low temperature diesel combustion are systematically examined. Although smokeless and ultra-low NOx combustion can be realized regardless of mixture homogeneity as long as the temperature is sufficiently low, fuel-air mixing is vital for an acceptable combustion efficiency. Finally, the operating range of smokeless and ultra-low NOx diesel combustion with low compression ratio and low cetane number fuels are discussed.
