Component s of Diesel Power Plants–Lecture Notes

Component s of Diesel Power Plants


1. Engine

2. Air Intake System

3. Engine Starting system

4. Fuel System

5. Exhaust System

6. Cooling System

7. Lubricating System


· It’s the main component of plants which develops power.

· Types : Two stroke, Four strokes.

· Air is passed into the cylinder, fuel is also injected.

· The fuel is burned and bring gases expand and do work on piston.

· Shaft of engine is coupled to generator. Burned gases are exhaust to atmosphere.

Air intake system:

· Removes dust from atmospheric air & supplies fresh air to engine.

· Types of filters :

1. Dry or oil bath filter.

2. Oil immersed type of filter.

Precaution’s for location:

1. Should not be located inside engine room.

2. Air intake line should not be too small or too long.

3. Air should not be taken from a confined space.

Engine Starting System:

Used to start the engine in cold conditions by supplying air.

Starting methods:

1. Auxiliary engine.

2. Self-starters

3. Compressed air system.

Auxiliary engine:

Auxiliary engine located close to main engine and driven through clutch and gears. Clutch is disengaged and engine is started.


Used in small diesel engines. Motor draws heavy current & designed to work continuously for 30sec after which it is cooled.

Compressed Air System:

Used in large diesel engines.

Compressed air supplied from air tank.

Fuel System:


· Storage Tank

· Fuel pump

· Strainers

· Meters

· Day Tanks (Supplies daily fuel need of engines and contains min 8hours of oil requirement)

1.Fuel Injection system:


1. Filters fuel.

2. Measures correct quantity of fuel to be injected.

3. Time the fuel injection.


1. Individual pump injection system.

2. Common rail injection system.

3. Distributor.

Individual Pump Injection System:

· Individual pump is connected to each fuel nozzle.

· Nozzles contain delivery value actuated by oil pressure.

· High cost of manufacture.

Common rail injection system:

· Single pump supplies fuel to header.

· Control valve is present to set the amount & time of injection of fuel.

Distributor System:

There os a pressure pump which meters the fuel & time of injection. Fuel enters the distributor blocks. From there fuel is distributed to cylinders in correct order.

2.Fuel Pump :

· Measures & delivers correct quantity of fuel at high pressure to injector.

· It consists of plunger. When it moves down , oil comes into the barrel through ports SP & Y when it moves up, fuel gets compressed and lifts delivery value & fuel flows to injected through passage (p).

3.Fuel Injection:

· Delivers fuel into combustion chamber where fuel is mixed with air.

· Fuel from pump enters through passage and lifts nozzle value. Fuel travels down nozzle & injected to cylinder. The injection pressure can be adjusted by adjusting the screw present above the spring.

Exhaust System:

Discharge engine exhaust to atmosphere. Includes silencers & connecting ducts.

Lubricating System:

It is used to reduce friction of moving parts & reduce wear & tear of the engine.


· Oil pumps

· Oil tanks

· Filters

· Coolers & pipes.


1. Wet sump lubrication system

i)Splash System

ii)Semi pressure system

iii)Fuel pressure system

2. Dry sump lubrication system.

3. Mist sump lubrication system.

Splash System:

· Used in 4 stroke stationary engines.

· Bottom of sump contains lubricating oil. Scoop is located at the bottom which splashes oil from all the parts.

· Suitable for low & medium speed engines.

Semi pressure System:

· Combination of splash & pressure systems.

· Oil is pumped from the sump through a filter and fed to main bearings.

· Less cost.

Full pressure system:

· Oil is pumped from sump through filter under pressure to various parts for lubrication.

· Oil is supplied to big end & small end bearings.

Dry sump lubrication system:

· Used in two stroke cycle engines.

· Mixture of oil & fuel is induced through carburetor & is vaporized.

Cooling System:

Carries heat generated inside engine cylinder.


1. Air cooling

2. Liquid cooling

i)Thermo-syphon cooling

ii)Forced or pump cooling

iii)Cooling with thermostatic regulator.

iv)Pressurized water cooling.

Air cooling:

· Engine is cooled by atmospheric air, which flows around engine.

· Used in scooters , motor cycles.


1. No danger of coolant leakage.

2. Simple design.

3. Less weight.

4. Easy installation.


1. Non uniform cooling.

2. Less output.

3. More maintenance.

4. Used in small engines only.

5. Noisy operation.

6. More maintenance.

Liquid Cooling:

Thermo Siphon Cooling:

· Hot water goes up and cold water comes down due to density without any pump.

· Top of radiator is connected to top of water jacket by a pipe & bottom of radiator to bottom of water jacket.

· Water travels down the radiator across which air is passed to coal it. Simple, Cheap , but slow cooling.

Forced cooling by pump:

· Pump forces water to circulate to engine.

· It may cause over cooling which causes corrosion.

Thermostatic Cooling:

· Thermostat maintains desired temperature to increase heat transfer in radiator.

Pressurized water cooling:

High water pressure is maintained to increase heat transfer in radiator.

Evaporative Cooling:

Water is allowed to evaporate by absorbing latent heat of evaporation from the cylinder walls.

The temperature of cooling water is allowed to reach 100c.

Governing System:

It is used to regulate the speed of the engine. This is done by varying the fuel supply according to the engine load.