Introduction
The subject Internal Combustion (I.C.) Engine and Gas Turbine deals with the study of machines that convert chemical energy of fuel into mechanical power. These prime movers play a crucial role in transportation, power generation, aviation, and industrial applications. Understanding their principles, components, working cycles, and performance is essential for mechanical engineers.
1. Prime Movers
A prime mover is a machine that converts energy from natural sources into mechanical energy.
Examples:
- I.C. engines
- Gas turbines
- Steam turbines
- Hydraulic turbines
Among these, I.C. engines and gas turbines are widely used because of their high efficiency, compact size, and fast starting capability.
2. Introduction to Internal Combustion (I.C.) Engine
An Internal Combustion Engine is a heat engine in which the combustion of fuel takes place inside the engine cylinder, and the high-pressure gases produced directly act on the piston to produce mechanical work.
Definition
An I.C. engine is a device that converts the chemical energy of fuel into mechanical energy through combustion inside the engine.
3. Basic Principle of I.C. Engine
The working principle of an I.C. engine is based on:
- Combustion of fuel inside the cylinder
- Generation of high-pressure and high-temperature gases
- Expansion of gases pushing the piston
- Conversion of linear motion of piston into rotary motion of crankshaft
4. Main Components of an I.C. Engine
- Cylinder
- Piston
- Connecting rod
- Crankshaft
- Inlet valve
- Exhaust valve
- Spark plug (SI engine)
- Fuel injector (CI engine)
Each component plays a vital role in efficient power production.
5. Classification of I.C. Engines
5.1 Based on Type of Ignition
- Spark Ignition (SI) Engine – Petrol engine
- Compression Ignition (CI) Engine – Diesel engine
5.2 Based on Number of Strokes
- Two-stroke engine
- Four-stroke engine
5.3 Based on Fuel Used
- Petrol engine
- Diesel engine
- Gas engine (CNG, LPG)
5.4 Based on Cooling Method
- Air-cooled engine
- Water-cooled engine
6. Applications of I.C. Engines
- Automobiles (cars, bikes, trucks)
- Agricultural machines (tractors, pumps)
- Power generators
- Marine engines
- Construction equipment
7. Advantages of I.C. Engines
- High thermal efficiency
- Compact size
- Quick starting
- Low initial cost
- Suitable for mobile applications
Limitations
- More noise and vibration
- Exhaust pollution
- Limited power output compared to turbines
8. Introduction to Gas Turbine
A Gas Turbine is a rotary internal combustion engine that converts the energy of hot gases into mechanical work by expanding them through turbine blades.
Definition
A gas turbine is a power plant in which air is compressed, fuel is burned, and the resulting hot gases expand through a turbine to produce power.
9. Basic Components of a Gas Turbine
- Compressor – Compresses air
- Combustion Chamber – Burns fuel with compressed air
- Turbine – Produces mechanical power
- Exhaust system
10. Working Principle of Gas Turbine
The gas turbine works on the Brayton cycle:
- Atmospheric air enters the compressor
- Compressed air enters the combustion chamber
- Fuel is injected and burned at constant pressure
- Hot gases expand through the turbine
- Turbine rotates the compressor and produces useful work
11. Classification of Gas Turbines
11.1 Based on Application
- Power generation turbines
- Aircraft gas turbines
- Industrial gas turbines
11.2 Based on Cycle
- Open cycle gas turbine
- Closed cycle gas turbine
11.3 Based on Shaft Arrangement
- Single-shaft turbine
- Two-shaft turbine
12. Applications of Gas Turbines
- Aircraft propulsion (jet engines)
- Power plants
- Marine propulsion
- Oil and gas industries
- Peak load power generation
13. Advantages of Gas Turbines
- High power-to-weight ratio
- Smooth and continuous power output
- Fewer moving parts
- Suitable for large power generation
Limitations
- Lower efficiency at part load
- High initial cost
- Requires high-quality fuel
- Complex materials due to high temperatures
14. Comparison Between I.C. Engine and Gas Turbine
| I.C. Engine | Gas Turbine |
|---|---|
| Reciprocating type | Rotary type |
| Lower power output | Very high power output |
| Suitable for vehicles | Suitable for aircraft and power plants |
| Higher efficiency at small scale | Better for large-scale power |
15. Importance of Studying I.C. Engine and Gas Turbine
- Fundamental subject for mechanical engineers
- Essential for automotive and aerospace fields
- Helps understand power generation systems
- Basis for advanced subjects like thermal engineering
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