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Unformatted text preview: the facility pays
$0.075/kWh for electricity. SOLUTION We take the turbine as the system (Fig. 7–30). This is a control volume since mass crosses the system boundary during the process. We note that
there is only one inlet and one exit and thus m 1 m 2 m .
Assumptions 1 This is a steady-flow process since there is no change with time
at any point and thus mCV 0, ECV 0, and SCV 0. 2 The turbine is adiabatic and thus there is no heat transfer. 3 The process is reversible. 4 Kinetic
and potential energies are negligible.
Analysis The assumptions above are reasonable since a turbine is normally
well-insulated and it must involve no irreversibilities for best performance and
thus maximum power production. Therefore, the process through the turbine
must be reversible adiabatic or isentropic. Then, s2 s1 and State 1: P1
T1 5 MPa
115 K State 2: P2
s2 1 MPa
1 h2 232.2 kJ/kg
4.9945 kJ/kg · K
222.8 kJ/kg Also, the mass flow rate of liquid methane is ·
r1V 1 (422.15 kg...
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This document was uploaded on 11/28/2012.
- Spring '09