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mixture since sf
sg. Thus we need to find the quality at state 2s first: x2s s2s sf
sfg 6.9212 1.0910
6.5029 0.897 and h2s hf x2s hfg 340.49 0.897 (2305.4) 2407.4 kJ/kg By substituting these enthalpy values into Eq. 7–61, the isentropic efficiency of
this turbine is determined to be hT h1
2407.4 0.666, or 66.6% (b) The mass flow rate of steam through this turbine is determined from the
energy balance for steady-flow systems: ·
Wa, out m h2a
m 1 h2a)
3.65 kg/s 2682.5) kJ/kg cen54261_ch07.qxd 11/18/03 9:57 AM Page 315 315
CHAPTER 7 Isentropic Efficiencies of Compressors and Pumps
The isentropic efficiency of a compressor is defined as the ratio of the work
input required to raise the pressure of a gas to a specified value in an isentropic manner to the actual work input:
hC Isentropic compressor work
Actual compressor work ws
wa (7–62) Notice that the isentropic compressor efficiency is defined with the isentropic
work input in the numerator instead of in t...
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This document was uploaded on 11/28/2012.
- Spring '09