Recall the steam power plant of Example 4.1 in Chapter 4b. Assume that the pump is adiabatic and that the temperature of the water increases by 0.5°C due to friction as it passes through the pump, as in the following figure:
Under these conditions (10 MPa, 40°C) we normally treat liquid water as an incompressible liquid. Determine:the pump adiabatic efficiency (ηP) defined as the isentropic pump work divided by the actual pump work required to drive the pump. [ηP = 83%]
Note: In solving this problem we recall the following relations for an incompressible fluid:
= 4.18 kJ/kg.K and specific volume v = 0.001 m3/kg.
Thus for the isentropic process: (Δs = 0) ⇒ T2 = T1 (ΔT = 0).
Engineering Thermodynamics by Israel Urieli is licensed under a Creative Commons Attribution-Noncommercial-Share Alike 3.0 United States License