Turbines and Pumps or Compressors

EXAMPLE 2.19 You wish to pump 0.001 m /s of water from a well to your house on a mountain, 250 m above. 

Pump POWGT Calculate the minimum power needed by the pump, neglecting the friction between the flow- 

SOLUTION Can you draw a schematic of this process We need to write the energy balance. This system is at steady-state, with one stream in and one stream out. When working with macroscopic potential energy, it is often convenient to write the balance on a mass (rather than mole) basis. We will neglect the bulk kinetic energy of the water at the inlet and outlet and the heat loss through the pipe. Since there are no frictional losses, the exit temperature is the same as the inlet therefore, their enthalpy is equal. Thus, the first law simplifies to  

---