Rankine Efficiency

A Rankine cycle can be regarded as a modified Carnot cycle. 

In a Carnot cycle steam from a turbine is condensed only partially to liquid - and a feed pump or compressor must compress a mixture of liquid and vapor to boiler pressure. For handling both liquid and vapor a large compressor is required.

In a Rankine cycle steam from a turbine is condensed completely to liquid - and the liquid can be compressed to boiler pressure with a relatively small feed pump.

The efficiency of the Rankine cycle can be expressed as

μ_R = H_i - H_e / H_i - h_c                                   (1)

where

μ_R = Rankine efficiency

H_i = heat at turbine inlet (kJ/kg)

H_e = heat at turbine outlet (kJ/kg)

h_c = sensible heat in exhaust (kJ/kg)