What is actual Rankin Cycle?

Actual Rankin Cycle:

In actual Rankin cycle, the processes are deviated from those of Ideal Rankin cycle.
Solid lines are showing ideal processes and dotted lines are showing actual processes.

1’-2’: Actual adiabatic expansion of superheated steam in the turbine. Turbine is surrounded by insulating material such as fiber glass or asbestos to prevent heat loss.

2’-3’: Actual process of condensation.

3’-4’: Adiabatic rise in pressure in the pump.

S’2 is higher than S2 and S4 is higher than S4, showing that entropy is generated in these processes.

Isentropic Efficiency
= Actual work/ Ideal work when expansion is isentropic.

Unfortunately, the entropy is generated in cases, the expansion and the compression.

4’-5’: Heating in the economizer. 

5’-6’: Actual process of heating in the boiler.

6’-1’: Super-heating process in the super heater.

It must be mentioned here that all the process in the Rankin Cycle are control volume as mass is entering and leaving and also the heat and work.



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