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A 7-hp (shaft) pump is used to raise water to a 15-m
Chapter 5, Problem 75P(choose chapter or problem)
A 7-hp (shaft) pump is used to raise water to a 15-m higher elevation. I f the mechanical efficiency of the pump is 82 percent, determine the maximum volume flow rate of water.
Questions & Answers
QUESTION: Problem 75P
A 7-hp (shaft) pump is used to raise water to a 15-m higher elevation. I f the mechanical efficiency of the pump is 82 percent, determine the maximum volume flow rate of water.
ANSWER:
Solution 75P
A 7-hp (shaft) pump is used to raise water to a 15-m higher elevation which is as shown in the fig below. The mechanical efficiency of the pump is 82 percent. The maximum volume flow rate of water can be determined by solving the energy equation for steady incompressible flow through a control volume between the two points that includes the pump and the pipe.
Step 1 of 2
We choose points 1 and 2 at the free surfaces of the lower and upper reservoirs, respectively, and take the surface of the lower reservoir as the reference level ( = 0). Both points are open to the atmosphere (
) and the velocities at both locations are negligible (
= 0).
The energy equation reduces to
(
+
=
(
+
+
=
=
The useful pumpin power is
=
= (0.82) (7 ) = 5.74 hp = 4280.318 W