Assignment 2
1) The case simulation was done on a single-cylinder Spark Ignition Engine from the Tutorial at 1800 RPM.
The Results are:
Air Flow Rate: The amount of air entering into the cylinder through the Intake valve. It is a very important parameter while calculating the volumetric efficiency.
The Air Flow Rate of this simulation is: 26.64 kg/h
BMEP: Brake Mean Effective Pressure (BMEP) is the mean pressure that measures the actual output pressure that is acting on the crankshaft.
The BMEP of the simulation is: 10.6 bar
BSFC: The amount of fuel that is used to produce work at the crankshaft output. It is generally used to compare the efficiencies of an engine.
The BSFC of the simulation: 239.17 g/kW-hr
In cylinder Pressure: It indicates the maximum amount of pressure developed in the engine cylinder.
The maximum In-cylinder Pressure: 48.89bar.
2) Increase the power output at 3600 rpm by 10%?
ANS: We can increase the Power by 10% in the natural aspirated I.C engine with a constant rpm by altering these parameters of the engine.
- Increasing the stroke length of the engine.
- Increasing the bore of the engine.
- Increasing the Compression Ratio of the engine.
- Adjusting the Air-Fuel ratio.
Increasing the stroke length of the engine.
For increasing the Power the stroke length is changed from 86.07 to 94.677
The results
Case1: 16.69kW
case2: 18.324 kW
If we compare the Brake power in both cases it can be noticed that the power is increased by approximately 10%
Increasing the bore length of the engine.
For increasing the Power the bore is changed from 86 to 89.8
The results
Case1: 16.69kW
case2: 18.33 kW
If we compare the Brake power in both cases it can be noticed that the power is increased by approximately 10%
Increasing the Compression Ratio of the engine.
For increasing the Power the Compression ratio is changed from 86 to 89.8
The results
Case1: 16.69kW
case2: 17.28kW
Case3: 17.85kW
Case4: 18.33kW
If we compare the Brake power in all cases it can be noticed that the power is increased by approximately 10% in case4 for the compression ratio 15.5.
The S.I engine running at this compression ratio is not recommendable because the high compression ratio always leads to the Abnormal combustion of the engine.
The best way for increasing the power output for a constant rpm is by installing either supercharger or turbocharger it increases the mass of the airflow entering into the cylinder that leads to the high output of the engine.