Various Definitions Related to the Mechanical Engineering Part 2

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1958

Entropy:
It is a thermodynamic property.

ds = dq/T

where, ds = change of entropy, dq = change of heat, T = Temperature.

In adiabatic process, entropy can not change. Actually,lacking or mal-adroitness of tranfering energy of a system is entropy.

Calorific Value of fuel:
It us the total amount of heat obtained from burning 1 kg solid or liquid fuel.

Boiler/Steam
Generator:
It is a closed vessel which is made of steel. Its function is to transfer heat to water to generate steam.

Economizer:
It is a part of boiler. Its function is to heat feed water which is supplied to boiler.

Superheater:
It is a part of boiler. Its function is to increase temperature of steam into boiler.

Air Preheater:
It is a part of boiler. Its function is to preheats the air to be supplied to furnace and it recover heat from exhaust gas.

Boiler Draught:
It is an important term for boiler. It is the difference of pressure above and below the fire grate. This pressure difference have to maintain very carefully inside the boiler. It actually maintained the rate of steam generation. This depends on rate of fuel burning. Inside the boiler rate of fuel burning is maintained with rate of entry fresh air. If proper amount of fresh air never entered into the boiler, then proper amount of fuel inside the boiler never be burnt. So, proper fresh air enters into the boiler only by maintaining boiler draught.

Nozzle:
Nozzle is a duct of varying cross-sectional area. Actually, it is a passage of varying cross-sectional area. It converts steam’s heat energy into mechanical energy. It is one type of pipe or tube that carrying liquid or gas.

Scavenging:
It is the process of removing burnt gas from combustion chamber of engine cylinder.

Supercharging:
Actually, power output of engine depends on what amount of air enter into the engine through intake manifold. Amount of entry any if increased, then must be engine speed will increased. Amount of air will be increased by increasing inlet air density. The process of increasing inlet air density is supercharging. The device which is used for supercharging is called supercharger. Supercharger is driven by a belt from engine crankshaft. It is installed in intake system.