In the Previous articles, we have discussed the Different types of Engines, Internal combustion Engines, 4 Stroke and 2 Stroke with Spark Ignition and Compression ignition. In this article, we are going to discuss the comparison of the Spark Ignition Vs Compression Ignition Engines.

An Engine is a device which transforms one form of energy into another form of Energy. An internal combustion engine is a heat engine where it undergoes different cycles of operations in a sequent manner to convert the thermal energy into useful work.

Working Principle of Engines

IC engines work on either Spark ignition or the Compression Ignition working principle.

Spark Ignition: Usually a petrol engine, where the combustion process of the air-fuel mixture is ignited by a spark from a spark plug

compression ignition: Generally the Diesel Engines, where the combustion process is caused by the elevated temperature of the air in the cylinder due to the mechanical compression.

Both the 2 stroke engines and the 4 stroke engines can work with the spark ignition and the compression ignition system. Check the classification of the heat engines here.

Comparison of Spark Ignition Vs Compression Ignition

1.Thermodynamic Cycle

Spark Ignition engine works on the Otto cycle built by Nicholas A.Otto, in 1876. It is a constant volume (Explosion) cycle.

Where the Compression Ignition Engine works on the Diesel cycle invented by Rudolf Diesel in 1876. It is a constant pressure cycle.

2. Introduction of Fuel

In Spark-Ignition Engine, the Air -Fuel mixture will be introduced into the combustion chamber during the suction stroke. To mix the Fuel with the air we need additional equipment called carburettor. For the ignition, we need a spark plug.

In Compression Ignition Engine, the fuel will be injected directly into the combustion chamber with the help of fuel injecter at the end of the compression stroke.

3. Ignition

AS you know In spark Ignition Engines A spark plug is used for the combustion process. (Additional Electrical energy will be required to create a spark with the spark plug)

In compression Ignition Engine, Self Ignition is occurred due to the elevated temperature of the air, where the air is highly compressed.

4.Type of Fuel

In spark Ignition Engine, Petrol (gasoline) is used. It is highly volatile and the self-ignition temperature of petrol (Gasolene) is high so that it will not get self-ignited. and the spark plug will be used for combustion.

In compression Ignition Engine, the Diesel is used as the Combustion fuel. It is non-volatile fuel. self-ignition temperature is comparatively low than petrol. So that it can self-ignite with the elevated temperature in the cylinder created by the highly compressed air.

5. Compression Ratio

In Spark-Ignition Engines, we use compression ratio ranging from 6 to 10. The upper limit of this compression ratio will be changed according to the antiknock quality of the fuel used.

In compression Ignition Engine, we use the compression ratio ranging from 16 to 20. The upper limit of this compression ratio will be changed according to the increase in the weight of the engine.

6. Engine Speed

Spark Ignition Engine is a compact engine and lite weight so that can run at very high speeds.

Compression engines are heavy and robust in design so that they run at low speeds compared to the spark ignition engines.

7. Thermal Efficiency

Due to less compression ratio, the thermal efficiency is lower. and where is Compression Ignition Engines, the thermal efficiency is high due to the high compression ratio used.

Conclusion

So far we have discussed the Comparison of Spark-Ignition Vs Compression Ignition with different scenarios such as the thermal efficiency and the speed, fuel, compression ratio and thermodynamic cycle. If you have any thought please let us know in the comment section below.