What is Engine?
An Engine is a machine with moving parts that converts power ito motion.
OR
An Engine is a machine that converts one form of energy into Mechanical energy.
Heat Engine
A heat engine is a system that converts heat or thermal energy into mechanical energy.
Classifications Of Heat Engine
Heat Engine may be classified into two main classes as follows -
1- External Combustion Engine
In this case , combustion of the fuel takes place outside the cylinder as in case of steam engine, where the heat of combustion is employed to generate steam which is used to move a piston in a cylinder.
Example - Hot Air Engine, Steam Turbine and closed gas turbine. These engine are generally used for driving locomotives, ships, generation of electric power etc.
Advantages of External Combustion Engine
• Starting torque is generally high.
• Almost any kind of fuel that is available can be used.
• Engine emission are also very low.
• very economical for huge power generation.
Disadvantages of External Combustion Engine
• Leakage of working fluid.
• Not suitable for low load requirments.
• Lubrication consumption.
• Size of engine is relatively big.
2 - Internal Combustion Engine
In this case combustion of the fuel with oxygen of the air occurs with in the cylinder of the engine.
Example - Gas engine, petrol engine, diesel engine
Advantages of Internal Combustion Engine
• Overall efficiency is high.
• Greater Mechanical Simplicity.
• lower initial cost.
• weight to power ratio is generally low.
• Easy starting from cold conditions.
• These units are compact and thus require less space.
• Starting time is very less.
Disadvantages of Internal Combustion Engine
• Fuel used is very costly like gasoline or diesel
• Engine emission are high compared to E.C. Engine.
• It is not suitable for large scale power
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