## An oil pump is drawing 44kW while pumping oil with a density of 860 kg/m3 at a rate of 0.1 m3/s. The inlet and outlet diameters of the pipe

Question

An oil pump is drawing 44kW while pumping oil with a density of 860 kg/m3 at a rate of 0.1 m3/s. The inlet and outlet diameters of the pipe are 8cm and 12cm, respectively. If the pressure increases by 500kPa going through the pump and the motoreffi ciency is 90%, determine the mechanical efficiency of the pump

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Physics
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2021-07-22T14:55:57+00:00
2021-07-22T14:55:57+00:00 1 Answers
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## Answers ( )

Answer:The mechanical efficiency of the pump is

91.8 %Explanation:Given;

input power, p = 44 kw

density of oil, ρ = 860 kg/m³

motor efficiency, η = 90 %

inlet diameter, d₁ = 8 cm

outlet diameter, d₂ = 12 cm

volume flow rate, V = 0.1 m³/s

pressure rise, P = 500kPa

output power = motor efficiency x input power

output power = 0.9 x 44 = 39.6 kW

Thus, the mechanical input power = 39.6 kW

The mechanical output power is given by change in mechanical energy;

The mechanical efficiency is given by

η = mechanical output power / mechanical input power

η = 36.347 / 39.6

η = 0.918

η = 91.8 %Therefore, the mechanical efficiency of the pump is

91.8 %