Tutorial No - CI Final

1CYL-CI ENGINE ANALYSIS:

1.COMPARISON OF SI AND CI ENGINE:

* SI Engine is a spark ignition engine which uses spark plug for the ignition to attain the self ignition temperature whereas CI is a self ignition engine which attains the self ignition temperature during the compression.

*As gasoline consists of high octane number it is slow burning characteristics so it works on low compression ratio range ,whereas diesel consists of high cetane number and hence it is fast burning characteristics and so it operates in the high compression ratio range.

*Swirl motion is much important in case of SI engine whereas Tumble model is more important for CI engines.

*SI engines can be used with the fuels such as petrol,LPG,CNG ,whereas the CI engine uses diesel and biodiesel.

*SI engines are driving comfort and suitable for NVH purposes,whereas the CI engines are fuel efficient.

* "KNOCKING" is the phenomenon of SI engines and "DETONATION" is the phenomenon of CI engines.

* SI engine emissions are often "CO,HC,NOX" and CI engine emissions are often "NOX".

* SI engines are always tries to operate in the "equivalence ratio" of "1" and CI engines are always lean burn engines.

*SI engines uses the "3 way catalytic converters" whereas the CI engines uses the

"DOC(Diesel oxidation of carbon monoxides),DPF(for particulate filter),SCR(Selective Catalytic Reduction)

2. BRAKE SPECIFIC FUEL CONSUMPTION:(BSFC)

* Brake specific fuel consumption is the measure of "Fuel efficiency of IC engines"

with respect to the output shaft . It is reduced when the speed of the engine is increased for a particular range .

BSFC = r/P

r - fuel consumption rate in grams per second(g/s)

p- power produced in watts

BSFC FOR 1CYL DI ENGINE:

SO its explaining that ,at 3600 RPM BSFC is 238g/Kw-h . So the engine's fuel efficiency is calculated based on the BSFC value .

EXHAUST TEMPERATURE:

The exhaust temperature for CI engines are very high as it operates on lean band

and also the particulate matters and the soots formed are defining the exhaust temperature.

AIR FUEL RATIO:

* As mentioned before the diesel engines are lean burn engines ,as the diesel consists of high cetane number it burns at faster rate . The stiochiometric air fuel ratio for diesel engines

are 14.7 ,so the diesel engines always operates at the higher "AFR"

* Here in this case the AFR range is about 20.78