Which is better SI or CI engine?

Introduction of the internal combustion engine

“Internal combustion engines are those types of engines in which combustion takes place with the help of an oxidizer like air, in the combustion chamber that is an integral part of the engine”.

A. Types of an internal combustion engine:

The internal combustion engine can be divided into two types on the basis of the ignition of fuel.

a) Spark-ignition engine (SI engine)

b) Compression ignition engine (CI engine)

a) Spark-ignition engine (SI engine):

Spark ignition engine also known as a petrol engine, are those type of internal combustion engine where combustion occurs through ignition Air- Fuel mixture with the help of a spark from the spark plug.

b) Compression ignition engine (CI engine):

“Compression ignition engine also known as a diesel engine, are those types of internal combustion engines where we would not require any spark system to burn the fuel mixture, infect the combustion occur through the heat that produces during compression of fuel at high temperature”.

Which engine is the most efficient?

Compression ignition engines are more reliable than Spark ignition engines.

I. Reason:

• Main reasons are:

• It uses low volatile fuel

• Low maintenance cost

• Produce less toxic exhaust to the environment

• More economical

• Most efficient

II. Explanation:

If we have a look at the ignition technologies of the Spark-ignition engine and the Compression engine we conclude that both work on the same ignition principle with few differences. As we know that CI engines run on diesel fuel which is a low volatile fuel. So it minimizes the chance of fire accidents due to its low volatility. It also reduces the maintenance cost of CI engines. CI engines have high thermal efficiency and durability as compared to SI engines. Environmental point of view, the exhaust system of CI engines is less harmful to the emission of CO2 in the environment. CI engines are more reliable and environmentally friendly and it is more economical as compared to SI engines. In the case of SI engines, there is a need to use a catalytic converter to reduce its toxic and harmful exhaust. Otherwise, it creates high pollution. This is a beneficial point in CI engines. It contributes less to pollution. Its ignition system runs automatically with the help of combustion temperature in engines.

Discuss the effect of the composition of the catalytic converter to reduce the emission of harmful gases from SI engine.

What is a catalytic converter?

The catalytic converter is a vehicle used in internal combustion engines to control or reduce the emission of harmful gases from the exhaust system and convert them into fewer hazardous gases through a chemical process. Catalytic converter controls the amount of toxic exhaust (NO, NO2, CO, CO2, O2, and SO2) from the SI engine. Therefore it is an important part of internal combustion engines.

Types of the catalytic converter:

a) Two-way catalytic converter

b) Three-way catalytic converter

The Catalytic converter in SI engines:

The catalytic converter works with the exhaust system of SI engines to remove harmful air pollutants like NOx, Cox, etc. It consists of an insulated chamber in which substrate, coated with catalytic material is present. Hot gas passes through it before being discharged into the air.

Catalyst: platinum or palladium metal oxides.

Working:

The activation energy of HC, CO, and NO can be lowered by the use of a reducing and oxidizing catalytic converter. During this process, the exhaust gas are reduced first, in this way we deplete oxides of nitrogen, and then this exhaust can be oxidized with the help of air to minimize the amount of carbon mono oxide. High internal porosity can be achieved by such activity. The engine runs with ideal speed and made stable conditions. By graphical representation, we noticed a decrease in the emission of harmful pollutants. It can only be possible through catalytic converters. The efficiency of SI engines can be increased, with minimum production of toxic pollutants. The graphical representation shows us the reduction of hydrocarbon content with the attachment of a catalytic converter. The harmful contents like CO2, CO, NO2, NO gradually becomes lower.

• It Significant lowers the amount of CO2.

• CO Increases Linearly With the Engine Speed.

• NO Emission improved, whether in less amount.

• Noticeable Improvement in SO2 Emission.

• Reduction in NO2 Emission with a Point Tends To Zero