An oil pump is drawing 40 kW of electric power while pumping

An oil pump is drawing 40 kW of electric power while pumping oil with rho = 860 kg/m^3 at a rate of 0.10 m^3/s. The inlet and outlet diameters of the pipe are 8 cm and 12 cm. respectively. If the pressure rise of oil in the pump is measured to be 360 kPa and the motor efficiency is 89 percent, determine the mechanical efficiency of the pump. |%

Solution

change in pressure,dP=360Kpa

Rate of discharge,Q=0.1 m^3/sec

mechanical output from pump= dP*Q=0.1*360*10^3=36000 watts

mechanical i/p=electrical o/p=40000 watts

efficiency of pump=(o/p)/(i/p)=(36000/40000)*100=90%