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
80 m/s NOZZLE
ηN = 92% 85 kPa FIGURE P7–108
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...
View Full Document