1. What is an engine ?
An engine is a mechanical system which transforms heat energy into mechanical energy
using fuel.
There are generally two types of engine: internal and external combustion engines.
1.1 Internal combustion engines are divided based on the following :
1 Type of fuel - diesel, petrol and gas.
2 Stroke – four-stroke and two-stroke.
3 Cylinders - single and multiple cylinders.
4 Cooling system.
2. What is a diesel engine ?
The diesel engine is a type of internal combustion engine, more specifically, a
compression ignition engine, in which the fuel isignited by the high temperature of
compressed gas, rather than a separate source of energy (such as a spark plug).
How diesel engines work
When gas is compressed its temperature rises. A diesel engine exploits this property in
order to ignite the fuel. Air is drawn into the cylinder of a dieselengine, and compressed
by the rising piston. This happens at a much higher compression rate than in a spark-
ignition engine. At the top of the piston stroke diesel fuel is injected into the combustion
chamber at high pressure through an atomising nozzle. It mixes with the hot, pressurised