It is expressed for turbines compressors and nozzles

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Unformatted text preview: following results: Isentropic: Most steady-flow devices operate under adiabatic conditions, and the ideal process for these devices is the isentropic process. The parameter that describes how efficiently a device approximates a corresponding isentropic device is called isentropic or adiabatic efficiency. It is expressed for turbines, compressors, and nozzles as follows: (k 1)/k 1 (n 1)/n 1 (kJ/kg) The work input to a compressor can be reduced by using multistage compression with intercooling. For maximum savings from the work input, the pressure ratio across each stage of the compressor must be the same. or, in the rate form, as · · Sin Sout 14243 Rate of net entropy transfer by heat and mass · Sgen 123 · Ssystem 123 Rate of entropy generation Rate of change of entropy (kW/K) For a general steady-flow process it simplifies to · Sgen · m e se · m i si · Qk Tk cen54261_ch07.qxd 11/18/03 9:58 AM Page 334 334 FUNDAMENTALS OF THERMAL-FLUID SCIENCES REFERENCES AND SUGGESTED READINGS 1....
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This document was uploaded on 11/28/2012.

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