Steam Turbine Efficiency calculator

[Kessels]

Hello Guys,
I wish to build a tool on our corporate website to calculate steam turbine efficiency based on a users requirements. It would be for the person (engineer) who knows Turbines and has realistic expectations and not a general school book efficiency calculator.
So what I seek from you experts is : What factors, inputs, and assumptions shall I take into account?

 

[CH5OH]

to calculate based on operating parameters:inlet pressure/temperature,outlet pressure/temperature,torque measurement,RPM,tensile strenght of shaft and its dimensions (to convert torque measurement to kW)steam tables/mollier diagram, understanding of basic thermodynamic cycles
to calculate based on assumptions would not grant you with much accuracy
you can estimate based on turbine manufacturer supplied technical documantation (performance curves)