Steam enters an adiabatic turbine steadily at 7 MPa, 5008C, and 45 m/s, and leaves at 100 kPa and 75 m/s. If the power output of the turbine is 5 MW and the isentropic efficiency is 77 percent, determine (a) the mass flow rate of steam through the turbine, (b) the temperature at the turbine exit, and (c) the rate of entropy generation during this process.

a) , b) , c)

Explanation:

a) The turbine is modelled by means of the First Principle of Thermodynamics. Changes in kinetic and potential energy are negligible.

The mass flow rate is:

According to property water tables, specific enthalpies and entropies are:

State 1 - Superheated steam

State 2s - Liquid-Vapor Mixture

The isentropic efficiency is given by the following expression:

The real specific enthalpy at outlet is:

State 2 - Superheated Vapor

The mass flow rate is:

b) The temperature at the turbine exit is:

c) The rate of entropy generation is determined by means of the Second Law of Thermodynamics: