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RANKINE CYCLE

The rankine cycle is a cycle that converts heatinto work . The heat is supplied externally to aclosed loop, which usually uses water.

By this cycle about 90 percent of electric power isproduced.

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Water is heated, turns into steam and spins a steam turbine which

drives an electrical generator. After it passes through the turbine, the

steam is condensed in a condenser and recycled to where it was

heated; this is known as a Rankine cycle.

STEAM CYCLES

RANKINE CYCLES:

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Process 1-2 :

Water from condenser at low pressure is pumpedinto boiler at high pressure. This process is reversibleadiabatic

Process 2-3:

Water is converted into steam at constant pressure

by addition of heat into boiler.

Process 3-4:

Reversible adiabatic expansion of steam in steam

boiler.

Process 4-1:

Constant pressure heat rejection in condenser toconvert condensate into water.

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EFFICIENCY OF RANKINE

CYCLE We know that efficiency is proportional to

1-T(L)/T(H)

That is, to increase efficiency one should increaseaverage temperature at which heat is transferred toworking fluid in boiler and decrease the temperatureat which heat is rejected from the working fluid incondenser.

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VARIOUS METHODS TO

INCRESE EFFICIENCY:

1)Decreasing the condenser pressure

2)superheating steam to higher temperatures

3)increasing the boiler pressure

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INTERNALLY IRREVERSIBLE

RANKINE CYCLE:

This is due to fluid friction.

That there is a loss of energy which we apply, sothis makes rankine cycle irreversible.

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EXTERNALLY IRREVERSIBLE

RANKINE CYCLE: DUE TO TEMPERATURE DIFFERENCES BETWEEN

COMBUSTION GASES AND WORKING FLUID ONSOURCE SIDE

TEMPERATURE DIFFERENCE BETWEEN CONDENSINGWORKING FLUID AND CONDENSER COOLINGWATER ON SINK SIDE.