The Rankine cycle can be regarded as a modified Carnot cycle where the vapor out of the turbine is condensed completely before it is feed into a boiler with a relatively small feed pump. With the Carnot process the vapor from the turbine is very wet and a compression would require a large compressor dealing with a non-homogenous mixture.
The efficiency of the Rankine cycle can be expressed as
μR = Hi - He / Hi - hc (1)
μR = Rankine efficiency
Hi = heat at turbine inlet (kJ/kg)
He = heat at turbine outlet (kJ/kg)
hc = sensible heat in exhaust (kJ/kg)