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

Q1) Compare SI vs CI and list down differences

SI	CI
Otto cycle Compression Ratio 7 to 9 Level of Noise and Vibration is less due to compression ratio starting is easier due to requaire less cranking effort Specific fuel consumption is more The burning of fuel at Constant Volume Ignition of air-fuel by Spark Plug Operation speed range 3000 to 6000 Thermal Efficiency is low cheaper coust due to less compression Pressure range 6 to 12 bar, Temperature range 250 oC to 300 oC	Diesel Cycle Compression Ratio 15 to 19 Higth Level of Noise and Vibration because works in very high compression ratio It is heavier in wheig due to higth pressure developed Big efford to starting due high compression Less Specific fuel consumption The burning of fuel at Constant pressure Auto Ignition by injection of fuel into the hot compressed air Operation speed 400 to 3500 Thermal efficiency is high Pressure range 35 to 40 bar, Temperature range 600 oC to 700 oC

Q2) Comments on following parameters

• BSFC

Brake specific fuel consumption is also known by th power-specific fuel consumption or specific fuel consumption, Its literaly how much fuel the car uses compared by how much power it produces. To calculate brake specific fuel consumption you should get fuel consumption divided by power, the results are given in kilowatts per hour.

• Exhaust Temperature

It can be one of the most important gauge on a turbo-diesel-powered vehicle It can warn the driver of situations that are potentially damaging to the engine, and it can also be used as a guide for optimizing fuel economy. The knowledge of the exhaust gas temperature is necessary and very important for the management and diagnosis of the exhaust gas aftertreatment system.

• A/F ratios

Air-fuel ratio (A/F) is the ratio between the mass of air and mass fuel used by the engine when running. The AFR is the quantity of air over the quantity of fuel injected in each cylinder of the engine compared with stoichiometric condition. This variable is characterizes the quality of the combustion and the performances of the engine according to fuel consumption and gases emissions. For a gasoline engine, the stoichiometric air-fuel ratio is around 14.7:1 and for diesel engine it is 14.5:1.

Q3) Change MFB 50 and observe impact on performance

To open the cases we hed to declare MFB as variable and settled the parameter as needed.
case 1 MFB - 35 (standart) and case 2 MFB - 50.

We can see here that we`ve lost 6.6HP of power and also lost 13,2 N-m of torque.
The BSFC has increased 37,8 g/kW-h.

Here we can se on the plots that we`ve decreased the fraction of fuel burnt, and also as shown before we`ve increased the amount of fuel consumption (BSFC).

The conclusion is when you increse the MFB to 50, we`re burning more fuel with less power and torque. Also less efficiency.