Assignment 4

The single cylinder diesel engine tutorial was explored. Some of the important specs and performance results are provided below.

The engine is a 4-stroke single cylinder diesel engine. The engine is a square engine and in this tutorial there was no turbocharger used. This tutorial is the simplest representation of a diesel engine.

The image above shows the layout for the engine. The engine specs is as follows.

From th engine geometryical specs, we can conclude that this is a 700cc (0.7L) square engine.

Above image provides details of injector like amount of fuel injected, fuel temperature, injection duration etc,.

This image provides the details which tells the temperature at which the engine cylinder is operating. The operating temperature of cylinder head, piston and cylinder temperature can be seen here.

The chosed tutorial was run at only one case. The rpm was run at 3600 rpm and the max simulation cycle was set at 10 cycles. The results are provided below.

As we can see from the above image, performance of our engine is as folows.

Brake power= 36.3 KW (48.6 HP)

Torque= 96.2 Nm.

Air fuel ratio= 20.78

BSFC= 238.2 g/kWh.

BMEP= 15.4 bar.

The attached image provides the amount of pollutants in ppm.

NOx= 1110.21

HC= 0.07

CO= 2.33

CO2= 96724.4

We can also see the max in cylinder pressure= 117.1 bar.

The above plot represents the rise and fall of pressure inside the cylinder. The pressure reacehed maximum at 6 degree crank angle.

This plot represents temperature characteristics inside the cylinder. The temperature reached peak value at 43 degree crank angle.

This plot represents fuel burn rate.The injected fuel was burned alomst completely at 75 degree crank angle.

2) Some of the major differences are listed below after comparing above diesel engine with single cylinder 4-stroke petrol engine tutorial file.

(i)In this tutorial file the injector injects fuel inside port and not directly inside the cylider whereas it is the latter case with diesel engine. And after detailed comparison, both injectors requires data differently.

As it can be seen from the above image, injector for SI engine requires the user to give data for delivery rate and the required air-fuel ratio that is required to be maintained. Whereas for diesel injector, the user is required to provide approximate data for maximum mass of fuel to be injected. The software decides air-fuel ratio based on the methodology "TotalCompostion".

The above image represents engine geometry and after coparing with 1 cylinder diesel engine, this SI engine has smaller capacity.

The performance of this SI engine is also lower compared to the diesel engine.

3) Some of the major differences are listed below.

SI Engine CI Engine

Power output = 16.7 kW. Power output = 36.3 kW.

Torque output = 44.3 Nm Torque output = 96.2 Nm.

A/F ratio = 14.51 A/F ratio = 20.78.

Compression ratio = 9.5 Compression ratio = 16.5

BSFC = 241.8 g/kWh BSFC = 238.2 g/kWh

Max in cylinder pressure = 58.9 bar Max in cylinder pressure = 117.11 bar

Max temperature = 2623 K Max Temperature = 2042 k

Exhaust gas temperature = 1209 K Exhaust gas temperature = 1039 K

4) MFB50 was changed for the above SI engine from 8 to 20 and some of the major changes observed are listed below.

Power output dropped to 15.7 kW.

Torque output dropped to 41.7 Nm.

BSFC increased to 256.8 g/kWh.

Max pressure decreased to 42.61 bar.

Max temperature decreased to 2557 K

Huge increase in amount of CO emissions.

CO emissions increased from 514.74 ppm to 1149.27 ppm.