Concept explainers
An oil pump is drawing 18 kW of electric power while pumping oil with p = 860 kg/m3 at a rate of 0.1 m3/s. The inlet and outlet diameters of the pipe are 8cm and 12 cm. respectively. If the pressure rise of oil in the pump is measured to be 250 kPa and the motor efficiency is 95 percent, determine the
The mechanical efficiency of the pump.
Answer to Problem 109P
The mechanical efficiency of the pump is
Explanation of Solution
Given information:
The input electric power is
Write the expression for the Bernoulli's equation.
Here, the pressure of the air before enter in the tunnel is
Write the expression for the mechanical efficiency of the pump.
Here, the work done by pump is
Write the expression for the mechanical efficiency of motor.
Here, the work done by motor is
Write the expression for the velocity at inlet.
Here, the volumetric flow rate is
Write the expression for the velocity at outlet.
Here, the outlet diameter is
Write the expression for the mass flow rate.
Calculation:
Substitute
Substitute
Substitute
Substitute
Substitute
The output power from the motor is used to drive the motor.
Substitute,
Conclusion:
The mechanical efficiency of the pump is
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Chapter 5 Solutions
Fluid Mechanics: Fundamentals and Applications
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