Problem Description


Mr. Williams has a small swimming pool in his backyard. The pump that pumps water from a well to the pool is broken. However, he found a used pump in a second-hand electric utility store. To insure that the pump matches his motor, he needs to figure out the power required to run the pump.

What is known:

  • The pump is capable of increasing the pressure of water up to 300 kPa.
  • The flow rate through the pump is 20 kg/min.
  • The pump has an isentropic efficiency of 85%.


What is the required power input to the pump?


  • Take the pump as a control volume.
  • Model the pump as an adiabatic pump.
  • Use the definition of isentropic efficiency of pump to calculate the enthalpy change of the process.
  • Use the energy balance to calculate the power input to the pump.