A counter flow double pipe heat exchanger has an outer pipe of 4-nom sch 40 commercial steel and an inner tube of 2-std type M copper. Hard water at an average temperature of 120°F flows in the tube at a flow rate of 80 gpm. City water flows in the annulus at a flow rate of 75 gpm and an average temperature of 50°F. The heat exchanger is a single DPHX with a length of 6 ft. After one year of service, the volumetric flow rates in the tube and annulus are estimated to experience a 2.5% reduction due to fouling. The fouling layer is primarily calcium carbonate.
Determine the pressure drop and the power required (watts) to move the water through the:

a. Inner tube for clean and fouled conditions

b. Annulus for clean and fouled conditions

c. Determine the increased power requirement (watts) due to fouling to move the water through the tube.

d. Determine the increased power requirement (watts) due to fouling to move the water through the annulus.

e. Based on your answers in Parts

(c) and (d), is fouling a concern from a hydraulic point of view?