The outer pipe in a double pipe heat exchanger is 4-nom sch 40 commercial steel.
The inner tube is 2-std type K copper. The fluid inside the inner tube is flowing at a volumetric rate of 20 gpm and the fluid in the annuls flows at 40 gpm. For this heat exchanger determine,

a. The hydraulic diameter of the annulus (ft)

b. The equivalent diameter of the annulus (ft)

c. The velocity of the fluid in the inner tube (ft/s)

d. The velocity of the fluid in the annulus (ft/s)