CI engine modelling

1. Following differences in different parameters can be seen when SI and CI engines are run at 3600 rpm :

Parameters	SI	CI
Bore	86 mm	100 mm
stroke	86.1 mm	100 mm
compression ratio	9.5	16.5
mean piston velocity	10.3 m/s	12 m/s
volumetric efficiency	93.50%	88.80%
exhaust pressure	1.023 bar	2.422 bar
intake pressure	0.995 bar	2.366 bar
intake temperature	325 K	367 K
Nox in ppm	180.72	1110.21
CO in ppm	514.74	2.33
HC ppm	0.16	0.07

2.

Following is the table having some details regarding the mentioned parameters to be discussed:

Parameters	SI	CI
BSFC	241.8 g/kw-h	238.2 g/kw-h
A/F ratio	14.51	20.78
exhaust temperature	1209 K	1039 K

As can be seen ,

• BSFC is less in case of CI in comparison to SI engine which indicates better fuel efficiency of CI efficiency.
• A/F ratio in case of SI is richer in comparison to CI engine which allows CI engines to be operated at higher compression ratios.
• Exhaust temperature in case of SI engine is more than CI engine .

3.Initially i took MB50 as 35 and i got the following performqance results:

Then i took MB50 as 45 and got the following performance from engine:

Then i took MB50 as 25 and got the following performance :