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Unformatted text preview: 2 at the end of the compression process (°C)? DO NOT ASSUME THAT THE SPECIFIC HEAT OF CO 2 IS INDEPENDENT OF TEMPERATURE. SOLUTION: Apply Eq. 5.74, Second Law for a control mass: Minimum T 2 will be if equality is used, so T 2 (using CO2 Tables for s o ) =[5.02924.9275)/(5.05604.9275)x50+50=89.6°C 3) (34%) A compressor for a fertilizer plant is to take 2 kg/s of ammonia at a pressure of 125 kPa and a temperature of 20°C, and compress it to a final pressure of 500 kPa. The compressor efficiency is 70%. The ammonia leaving the compressor is to be cooled to 40°C in a heat exchanger. ( Note: There are tables of thermodynamic data for ammonia in the text.) a) What power is required to drive the compressor (kW)? b) How much heat transfer must occur in the heat exchanger (kW)? SOLUTION: STATE TABLE: STATE P(kPa) T(°C) h(kJ/kg) s(kJ/kg•K) 1 125 20 (1534.2) (6.4588) 2s 500 (1764.2 6.5488 2a 500 (1862.8) 3 500 40 (1557.9) a) b)...
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 Spring '07
 Dr.Kinne
 Thermodynamics, Heat, CO2, entropy change, argon

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