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HC EMISSIONS FROM SI ENGINES
Main sources of hydrocarbon emissions in the four-stroke, homogeneous charge spark ignition engines are:
(i) |
Flame quenching on the cylinder walls |
(ii) |
Flame quenching in crevices |
(iii) |
Absorption and desorption in oil film on cylinder walls |
(iv) |
Absorption and desorption in carbon deposits in the chamber |
(v) |
Misfired combustion or bulk gas quenching |
(vi) |
Liquid fuel in the cylinder |
(vii) |
Exhaust valveleakage,and |
(viii) |
Crankcase blow by gases |
In the vehicles, fuel evaporation from fuel tank and fuel system is another source of unburned HC emissions.
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