6.5 A centrifugal pump and a gear pump are operating in series in a closed loop to deliver a 20% ethylene glycol solution at an average temperature of 10°C through a long pipe system. In the capacity range up to 2 m3/s, the pump performance equations expressed in terms of pressure increase as a function of capacity are given by A detailed friction analysis reveals that the pressure drop through the closed-
loop system is given by P = 20V 2 In the pump performance equations and system curve equation, the pressure changes are in kPa and the capacity is in m3/s.

a. On the same plot, show the system curve, the performance curves for each pump, and the performance curve of the combined series pumps in terms of head (m) as a function of capacity (m3/s). Draw the curves from 0 to 2 m3/s.

b. Write a simulation of the system and determine its operating point.

c. If the economic velocity of the ethylene glycol for this system is 10 ft/s, specify the standard schedule steel pipe required for this application.