The on-line calculation of exhaust steam's enthalpy for steam turbines is an important link in thermodynamic performance test and on-line supervision of thermal power units.At present

the calculation method of exhaust steam's enthalpy has certain limitations in varying degree

hence

it is necessary to analyse and compare the algorithms of exhaust steam's enthalpy.The commonly used calculation methods for exhaust steam's enthalpy are as follows:energy balancing method

curve's extrapolation method

equivalent enthalpy drop method

Fulugel formula's method

and relative internal efficiency method.By using these said methods

the exhaust steam's enthalpy of a N220-12.7 type steam turbine has been calculated respectively as concrete examples.Through analysis and comparison of the calculation results

the individual condition of application and measures of improvement for these said calculation methods have been obtained .