What are the parameters required to calculate the overall efficiency of a steam turbine and how to calculate. Is there are certain assumptions to be made while calculating the overall efficiency of a steam turbine.
The objective of a stream turbine is to extract all the available latent heat in steam and convert it to mechanical power. In any energy transfer system it is nigh impossible to achieve 99.999% efficiency because of friction, inertia and uncontrollable energy creep due to entropy. A simplistic observation would suggest that energy input=energy output in a direct system but a turbine is a mechanical obstruction that introduces friction and inertia issues. To compound the initial issues are the aerodynamics of the turbine according to the methods of kinetic energy extraction from the steam.
Am example would be an initial pressure of 2700 psi and post extraction pressure of 0.17 psi. The thermal gradient may well drop from 300°C to ambient temperature before the fluid is cycled again. The formulae for the calculations you speak of are complex, requiring specific measurements and parameters.
Generally speaking, turbines only extract about 36% to 68% of their throughput.