Question

Water is being pumped from a large lake to a reservoir 25 m above at a rate of 25 L/s by a 16-kW (shaft) pump. If the irreversible head loss of the piping system is 5 m, determine the mechanical efficiency of the pump.

Answer 1

efficiency = 73.6 %

Step-by-step explanation:

given data

height = 25 m

flow rate = 25 L/s = 0.025 m³/s

head loss = 5 m

power = 16-kW (shaft)

to find out

mechanical efficiency of the pump

solution

we first find total head that need to supply that is = 25 + 5

total head Hm = 30

so now water power due to Hm is

water power = wQHm

water power = 1000 × 0.025 × 9.8 × 30

water power = 9.36 kW

so

efficiency of pump will be

efficiency =
`(water \ power)/(given \ power)`

efficiency =
`(7.36)/(10)`

efficiency = 73.6 %