# City water at 15c is heated to 55c in an electric

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Unformatted text preview: g EES (or other) software, study the effect of varying the nozzle isentropic efficiency from 0.8 to 1.0 on both the exit temperature and pressure of the air, and plot the results. 7–108 Hot combustion gases enter the nozzle of a turbojet engine at 260 kPa, 747°C, and 80 m/s, and they exit at a pressure of 85 kPa. Assuming an isentropic efficiency of 92 percent and treating the combustion gases as air, determine (a) the exit velocity and (b) the exit temperature. Answers: (a) 728.2 m/s, (b) 786.3 K 260 kPa 747°C 80 m/s NOZZLE ηN = 92% 85 kPa FIGURE P7–108 Entropy Balance 7–109 Consider a family of four, with each person taking a 5-min shower every morning. The average flow rate through cen54261_ch07.qxd 11/18/03 9:58 AM Page 341 341 CHAPTER 7 the shower head is 12 L/min. City water at 15°C is heated to 55°C in an electric water heater and tempered to 42°C by cold water at the T-elbow of the shower before being routed to the shower head. Determine the amount of entropy generated by this family per year...
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