EXAMPLE 7.7-3 Hydraulic Power Generation Water fows from an elevated reservoir through a conduit to a turbine at a lower level and out of the turbine through a similar conduit. At a point 100 m above the turbine the pressure is 207 kPa. and at a point 3 m below the turbine the pressure is 124 kPa. What must the water flow rate be if the turbine output is 1.00 MW? 100m 100 MN 124 P

Nitrogen gas enters a 0.500 m diameter pipe at 31.0 °C, 2.50 atm (absolute), and 4.00 m/s. The pipe rises 31.0 ft and then falls 81.0 ft. The nitrogen gas exits the pipe at 31.0 °C and z, ft 1.60 atm (absolute). The ultimate goal is to find AÉk and AEp in the process. T, °C z, ft Assume N, behaves ideally. P, atm (absolute) и, m/s T, °C P, atm (absolute) и, т/s What is V 1, the volumetric flow rate of nitrogen gas into the pipe section? V1 = m³/s What is m, the mass flow rate into the pipe? m = kg/s What is u2 the average velocity of N2 leaving the pipe section? u2 = m/s What is AĖk, the change in kinetic energy of the gas between the end and the start of the pipe section? ΔΕΚ - J/s

Transport Phenomena Question

[1] Repeat Example 7.10 (pages 288-289) but with the following exceptions: water is discharged at 9,000 kPa, and n=0.8. Calculate the work of the pump and AT using steam tables and equation 7.25

Water is stored in an elevated reservoir. To generate power, water flows from this reservoir down through a large conduit to a turbine and then through a similar-sized conduit. At a point in the conduit 89.5 m above the turbine, the pressure is 172.4 kPa and at a level 5 m below the turbine, the pressure is 89.6 kPa. The water flow rate is 0.800ms. The output of the shaft the turbine is 658 kW. The water density is 1000 kg m. If the efficiency of the turbine in converting the mechanical energy given up by the fluid to the turbine shaft is 89 % (n = 0.89). a) Draw a schematic diagram for the process b) Calculate the frictional loss in the turbine in J kg %3D

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Q.3 A converging-diverging nozzle is supplied by a huge air reservoir. The nozzle has a throat area of 10 cm? and an exit area of 20 cm?. The reservoir conditions are P. = 300 kPa and To = 30 °C. Determine the range of the back pressure over which (a) shocks appear in the nozzle, (b) oblique shocks form at the exit, and (c) expansion waves form. (d) Calculate the mass flow rate through the nozzle for the case in which a normal shock appears at the exit plane.

For the system shown in the Figure, Reservoir 1 has a water depth of 6 m and Reservoir 2 has a water depth of 14 m. The bottom of Reservoir 2 is at an elevation of 19 m above the bottom of Reservoir 1. The pump is required to deliver 400 l/s of water from Reservoir 1 to Reservoir 2. Given that the total energy loss in the system is 1 J/N, how much power must the pump deliver? Give your answer in kW to one decimal place. Reservoir 2 pump Reservoir 1 Power (kW) Round your answer to 1 decimal place.

Question 2 A water pump driven by an 800 W electric motor is used to pump water from the ground level to a tank at the rate of 20000 L/hour. Water is being discharged into the tank at 10 meters above the ground; this is the maximum rise this pump can achieve. The water and the ambient temperatures are both 10 °C. The inlet and outlet pipe diameters for the pump are both 8 cm, respectively. Determine: (1)/ The average inlet linear flow velocity of the water; 2) Assuming the efficiency of the electric motor is 95%, calculate the efficieney-of the motor-pump unit; 3) The pressure difference between the inlet and the outlet of the pump.