Week-4 : Basic Calibration of Single cylinder CI-Engine

Aim:- To compare the performances of the SI and CI engine on the basis of performance parameters.

Introduction:- 

• Spark Ignition (SI) Engine is a type of engine in which the combustion takes place by the spark generated by the spark plug.
• Compression Ignition (CI) Engine is an engine in which the combustion of fuel takes place by the heat of the compressed air.
• In this assignment we are going compare the performances of both the engine.

1)1-Cylinder DI Engine:-

2)1-Cylinder SI Engine:-

Question no.-01)

Answer:-

SI Engine:-

• Spark Ignition (SI) Engine is a type of engine in which the combustion takes place by the spark generated by the spark plug.
• It uses petrol as fuel and works on Otto cycle.
• Air-fuel mixture is inserted into the cylinder with help of carburetor.
• The compression of the fuel takes place but it has low compression ratio. 

CI Engine:-

• Compression Ignition (CI) Engine is an engine in which the combustion of fuel takes place by the heat of the compressed air.
• It uses diesel as fuel and works on the Diesel cycle.
• In the compressed ignition engine, only air enters into the cylinder during suction stroke.
• It has high compression ratio because of the high ignition temperature of the diesel fuel. The heat of the compressed air ignites the fuel. Due to the high compression ratio.

                                CI                                                                                       SI

    

      

2) Comments on following parameters

Both the engines are operated on the same RPM but due to the difference in their working operation, the results we are getting are different.

• BSFC:- In case of BSFC i.e. brake specific fuel consumtion, for CI engine it is 238.2 g/kW-h and for SI engine it is 0.397 g/kW-h, which are nearly the same values.

• Exhaust Temperature:- 
• CI max. temp.- 1033.5 K                                                                                           max. temp. for SI -1178.52 K                                                                                               

• The exhaust temperature profile for both engine is mostly similar but for CI engine its starting from around 900 K and end with same temperature.
• For SI engine it's starting from around 800K and end with same temperature.
• But the max. temp obtained at SI engine is higher than the CI engine.

• A/F Ratios :- For A/F Ratios, In CI engine it is 20.78 and for SI engine it is 14.51, which are having difference of 6.27, if we compare the values of CI & SI engine we can say that the A/F mixture is rich for SI engine. 

3) Change MFB 50 and observe impact on performance:-

In this we have taken 4 different values of the MFB (main duration)- 33, 40, 50, 60

 

The maximum power is obtained at the minimum value of the MFB i.e. 33. and power obtained is 49.4 HP. As we increase the MFB then the power of the engine is goes on decreasing.

• Conclusion:-

As the both engines are good for the vehicles on the basis of their respective operations, but if we see the volumetric effieciencies of both the engines SI engine(93.6%) is more efficient than that of CI engine(88.8%).