Without after-treatment, higher HC and CO emission level occur for HCCI fuel with ethanol and the highest HC (30g/kWh) and CO (300g/kWh) under lean mixture with equivalent ratio 0.11. Compared to EGR rate, the equivalent ration has more effect on HC and CO emission level.
The BUMP height and secondary wall-impingement distance were discovered to play an important role in producing a secondary space jet, reducing the quantity of fuel stuck on the wall and forming lean mixture, and their suitable values being 1.0-1.5mm and 0-2.0mm respectively.
A little amount of hydrogen supplemented to the gasoline-air mixture can extend the flammability limits of the mixture, increase the rate of flame propagation, accelerate the burning velocity of the lean mixture, thus improving the engine fuel economy and emissions.
The emissions characteristics at the idling condition and partial load conditions were studied by using MicroEFI system. The data show that, by applying the techniques of skip injection, ignition optimization and lean mixture combustion, the exhaust emissions of HC at idling condition can be reduced by 68%, CO by 60%, and at partial load condition HC can be reduced by 30%～40%, CO by 20%～60%, NOx by 35%～50%.
(An industrially important example of this situation would be the absorption of a gas from a lean mixture into a liquid-saturated ion exchange membrane.) The double Laplace transformation is applied to the system equations.
Laser-induced ignition of a very lean mixture can be controlled to provide local heat release and extinction in a flame.
When the piston reaches its highest point, this lean mixture spontaneously combusts from compression heating, as in a diesel engine.
The radiation effect is very small because of low-soot, low temperature combustion of the premixed lean mixture in a typical HCCI engine.
The low heat content of the lean mixture reduces the peak temperature of comb ustion, thus reduces NOx emissions.