A two-stage air compressor with intercooler shown in Fig. 6-25 compresses air (which is assumed dry)...

   
 
 
 

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A two-stage air compressor with intercooler shown in Fig. 6-25 compresses air (which is assumed dry) from 100 to 1200 kPa absolute. The following data apply to the components: m³/s Displacement rate = (0.05 m/s high-stage compressor Volumetric efficiency n. % = flow rate measured at compressor suction. m³/s displacement rate. m³/s (100) and for both compressors 1.4 Pdisch n. % = 104-4.0 Psuction The polytropic exponent nt in the equation piv=p₂v is 1.2. The intercooler is a counterflow heat exchanger receiving 0.09 kg/s of water at 22°C. The 12. P Intercooler UA= 0.3 kW/K 15. Pi 1200 kPa Air 100 kPa 1 = 26°C w kg/s Low stage Cooling water 22°C. 0.09 kg/s FIGURE 6-25 Two-stage air compression in Prob. 6.15. product of the overall heat-transfer coefficient and the area of this heat exchanger is UA= 0.3 kW/K. Assume that the air is a perfect gas. Use the Newton-Raphson method to simulate this system, determining at least the values of w.p..12 and 13. Use as a test for convergence that all variables change less than 0.001 during an iteration. Limit the number of iterations to 10. Ans.: w = 0.18 kg/s. 12 = 101.8°C. p. = 387.7 kPa, 13 = 43.84°C. High stage A two-stage air compressor with intercooler shown in Fig. 6-25 compresses air (which is assumed dry) from 100 to 1200 kPa absolute. The following data apply to the components: m³/s Displacement rate = (0.05 m/s high-stage compressor Volumetric efficiency n. % = flow rate measured at compressor suction. m³/s displacement rate. m³/s (100) and for both compressors 1.4 Pdisch n. % = 104-4.0 Psuction The polytropic exponent nt in the equation piv=p₂v is 1.2. The intercooler is a counterflow heat exchanger receiving 0.09 kg/s of water at 22°C. The 12. P Intercooler UA= 0.3 kW/K 15. Pi 1200 kPa Air 100 kPa 1 = 26°C w kg/s Low stage Cooling water 22°C. 0.09 kg/s FIGURE 6-25 Two-stage air compression in Prob. 6.15. product of the overall heat-transfer coefficient and the area of this heat exchanger is UA= 0.3 kW/K. Assume that the air is a perfect gas. Use the Newton-Raphson method to simulate this system, determining at least the values of w.p..12 and 13. Use as a test for convergence that all variables change less than 0.001 during an iteration. Limit the number of iterations to 10. Ans.: w = 0.18 kg/s. 12 = 101.8°C. p. = 387.7 kPa, 13 = 43.84°C. High stage