Challenge

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

RRamesh Arvind S30 Jan 2023

Aim:

Basic calibration of single cylinder CI engine.

Objectives:

1.Compare SI vs CI and list down differences (assignment no 2-SI)

2.Comments on following parameters

BSFC
Exhaust Temperature
A/F ratios

3.Change MFB 50 and observe impact on performance

SI and CI engine differences:

S.no	Spark Ignition Engine	Compression-Ignition Engine
1	SI engines are high-speed engines.	CI engines are low-speed engines.
2	SI engines have a low thermal efficiency	CI engines have high thermal efficiency.
3	Petrol is used as fuel, which has a high self-ignition temperature.	Diesel is used as fuel, it has a low self-ignition temperature.
4	Knocking takes place at the end of combustion.	Knocking takes place at the beginning of combustion.
5	SI engine works on the otto cycle.	CI engine works on the diesel cycle.
6	The homogeneous mixture of fuel, hence high pressure is generated.	A heterogeneous mixture of fuel, hence low pressure is generated.
7	Constant volume cycle.	Constant pressure cycle.
8	Spark plug is required	Spark plug is not required.
9	No fuel pump is used	Fuel pump is used to inject fuel
10	Engines are more compact and light.	Heavier and strong engines due to higher pressure involved
11	These engines have a smooth operation	Roughness in engine operation encountered, especially when the engine runs at high speed and low loads.
12	Compression ratio is low.	Compression ratio is high
13	Less Hydrocarbon is produced.	More hydrocarbon is produced.
14	The starting of SI engine is easy.	The starting of CI engine is difficult.
15	It is used in light commercial vehicles like motorcycle, cars etc.	It is used in heavy duty vehicles likes bus, trucks, ships etc.

BSFC:

BSFC is the measurement of efficiency of fuel by the engine that combusts the fuel air mixture and produces the rotational motion of the crankshaft. This is used for comparing the efficiency of the engine. BSFC is the ratio of the rate of fuel consumption and the effective power produced from the engine.

The BSFC calculation :-

BSFC [g/(kW⋅h)] = BSFC [g/J] × (3.6 × 10⁶) The conversion between metric and imperial units is: BSFC [g/(kW⋅h)] = BSFC [lb/(hp⋅h)] × 608.277.

Exhaust Temperature:

The exhuast temperature is the temperature of the gas after it leaves the combustion chamber.Exhaust gases normally discharges at a temperature of around 420°C (788°F).Diesel engine exhaust gases vary with speed and load. High loads and high speeds result in the highest temperatures. Generally, temperatures of 500–700°C (932–1293°F) are produced in the exhaust gases from diesel-cycle engines at 100% load to 200–300°C (392–572°F) with no load. Exhaust gases normally discharges at a temperature of around 420°C (788°F).

Exhaust gas treatment has a major influence on fuel consumption. Stringent regulations apply in relation to exhaust gas treatment with gasoline direct injection systems. It must be ensured that catalytic convertors also reach their activation temperature at low exhaust gas temperatures, particularly during part-load operation. Selective exhaust manifold heating strategies can be implemented by means of flexible multiple injection, thus effectively reducing hydrocarbon emissions during cold starts.

A/F ratio:

Air–fuel ratio is the mass ratio of air to a solid, liquid, or gaseous fuel present in a combustion process. The combustion may take place in a controlled manner such as in an internal combustion engine or industrial furnace, or may result in an explosion.

The ideal (theoretical) air-fuel ratio, for a complete combustion, is called stoichiometric air-fuel ratio. When the air-fuel ratio is higher than the stoichiometric ratio, the air-fuel mixture is called lean. When the air-fuel ratio is lower than the stoichiometric ratio, the air-fuel mixture is called rich. For a gasoline engine, the stoichiometric air-fuel ratio is around 14.7:1 and for diesel engine it is 14.5:1.

Procedure:

Open GT power console>> select engine performance>> select 1cyclDI engine

Engine cylinder geometry template:

The following table summarizes the major differences in their setup

Component	Parameter	1 cylinder SI	1 cylinder CI
Env-inlet	Pressure (bar)	1	2.4
	Temperature (K)	300	350
	Length (mm)	300	120
Intake Runner	Wall Temperature (K)	300	350
Cylinder	Bore (mm)	86	100
	Stroke (mm)	86.07	100
	Compression ratio	9.5	16.5
	Connecting Rod (mm)	175	220
	Clearance Height (mm)	1	0.5
Env-outlet	Pressure (bar)	1	2.4
Env-outlet	Temperature (K)	300	350

Injection duration parameters:

Combustion parameters:

Cylinder template:

Case setup for ci engine:

Report tables results:

Plots:

Pressure:

Temperature:

Comparing the SI engine performances:

Geometry dimensions of SI engine:

Combustionn chamber template:

GT post:

Pressure plot:

Temperature plot:

Changing MFB to 50:

Append the different cases in case setup and run the simulation.

Report table:

Plots:

Conclusion:

The CI engine is successfully designed with different speeds and observe the results of the different parameters.
Done the Comparison of the different parameters like BSFC,Air fuel Ratio,Exhaust Temperature of the SI and CI engines.
Change the main duration time and observe the performance of the engine.

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

Ship work like this
in your own course.

Talk to a career counsellor

Ship work like thisin your own course.

Talk to a career counsellor

Ship work like this
in your own course.