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help please! and discharging it through a hose nozzle with a diameter of 2 inche

ID: 1920368 • Letter: H

Question

help please!

and discharging it through a hose nozzle with a diameter of 2 inches. The total irreversible head loss of the system is 10 feet% and the nozzle is 8 feet above sea level. For a pump efficiency of 60 percent, determine the required pump horsepower. Also, what is the water exit velocity? Water enters a hydraulic turbine through a 30-cm pipe at a rate of 0.6 m3/s and exits through a 25-cm pipe. The pressure drop in the turbine is measured to 1.2 m of mercury. For a combined turbine-generator efficiency of 83 percent, determine the net electric power output. Assume alpha =1 .0.

Explanation / Answer

Entrance velocity V1 = Q / A_entrance

= 0.6 / (3.14 / 4 * 0.3^2)

= 8.49 m/s

Entrance loss = alpha*V1 ^2 / (2g)

= 1 *8.49^2 / (2*9.81)

= 3.676 m

Exit velocty = Q / A_exit

= 0.6 / (3.14 /4 *0.25^2)

= 12.22 m/s

alpha*V^2 / (2g)

= 1*12.22^2 / (2*9.81)

= 7.622 m

Pressure loss = rho*g*h = 1000*9.81*7.622 = 74771.8 Pascals = 74.77 kPa

dP = 1.2 m of Hg = 159960 Pascals = 159.96 kPa

Net dP = 159.96 - 74.77 = 85.18 kPa

Power = dP*Q

= 85.18*0.6

= 51.1 kW

Actual power = 51.1*eff = 51.1*0.83 = 42.4 kW