Cen54261ch07qxd 111803 957 am page 314 314

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Unformatted text preview: tential energies are negligible. 3 The turbine is adiabatic. 1 h1 wa h2a h2s Actual process t Exi ure ess pr ws P2 2a 2s s2s = s1 Isentropic process s FIGURE 7–49 The h-s diagram for the actual and isentropic processes of an adiabatic turbine. cen54261_ch07.qxd 11/18/03 9:57 AM Page 314 314 FUNDAMENTALS OF THERMAL-FLUID SCIENCES T,°C P1 = 3 MPa Actual process T1 = 400°C 2 MW 1 400 Isentropic process 3 MPa STEAM TURBINE 50 kPa 100 2 2s FIGURE 7–50 Schematic and T-s diagram for Example 7–14. P2 = 50 kPa T2 = 100°C s s2s = s1 Analysis (a) The enthalpies at various states are State 1: P1 T1 State 2a: P2a T2a 3 MPa 400°C 50 kPa 100°C h1 s1 3230.9 kJ/kg 6.9212 kJ/kg · K h2a 2682.5 kJ/kg (Table A–6) (Table A–6) The exit enthalpy of the steam for the isentropic process h2s is determined from the requirement that the entropy of the steam remain constant (s2s s1): State 2s: sf 50 kPa → sg s1) P2s (s2s 1.0910 kJ/kg · K 7.5939 kJ/kg · K (Table A–5) Obviously, at the end of the isentropic process steam will exist as a...
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This document was uploaded on 11/28/2012.

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