An insulated steam turbine receives steam at 8.0 MPa, 400°C, and a mass flow rate of 35 kg/s. For a steam exit pressure of 20 kPa, using your turbine model, plot the power produced for

Question

(a) exit qualities ranging from 0.85 to 1.0 and
(b) exit steam temperatures ranging from 65°C to 200°C.

Given: P1 = 8.0 MPa; T1 = 400°C; m?=35 kg/s; P2 = 20 kPa; Steam
State 1 is the inlet, state 2 is the outlet.
Assume: Q? = 0 (insulated) Also, for a turbine, assume steady-state, steady-flow, single-inlet, single-outlet flow, with ?KE = ?PE = 0

Answer 1

With these assumptions, the First Law for open systems reduces to W?=m?(h1?h2)

For steam, the following properties can be found:

h1 = 3138.3 kJ/kg

(a) Exit state enthalpy values depend on the quality



(b)



As the quality increases, and then as the exit temperature increases, less energy is removed by the turbine to produce power, and so the power production decreases.