Also notice that the inlet conditions and the exit

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Unformatted text preview: he denominator. This is because ws is a smaller quantity than wa, and this definition prevents hC from becoming greater than 100 percent, which would falsely imply that the actual compressors performed better than the isentropic ones. Also notice that the inlet conditions and the exit pressure of the gas are the same for both the actual and the isentropic compressor. When the changes in kinetic and potential energies of the gas being compressed are negligible, the work input to an adiabatic compressor becomes equal to the change in enthalpy, and Eq. 7–62 for this case becomes h2s h2a hC ws wa υ (P2 h2a (7–63) P1) h1 wt wa P2 h2a Actual process 2s h2s wa Isentropic process ws h1 1 Inlet state s2s = s1 s FIGURE 7–51 The h-s diagram of the actual and isentropic processes of an adiabatic compressor. (7–64) When no attempt is made to cool the gas as it is compressed, the actual compression process is nearly adiabatic and the reversible adiabatic (i.e., isentropic) process serves well as the ideal process. However, sometimes compressors are cooled intentionally by utilizing fins or a water jacket placed around the casing to red...
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This document was uploaded on 11/28/2012.

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