The hollow-fiber separator of Example 26.1 has 300 x 600 m fibers 1 m long and an

The hollow-fiber separator of Example 26.1 has 300 x 600 μm fibers 1 m long and an external area of 5.2 m². 

(a) With a permeate flow of 3.1 L. (STP)/min, what are the exit velocity and the pressure drop in the fiber lumen? 

(b) If a separator were made with the same membrane in the form of 150 x 300 μm fibers, what would be the pressure drop?

Example 26.1

A hollow-fiber separator with polysulfone membranes was arranged for counterflow and tested for air separation. At a feed rate of 20 L/min (STP), it gave 3.1 L/min of 19 percent O₂ as permeate and a residue with 17 percent O₂. The feed and residue gauge pressures were 40.0 and 39.5 lb_ƒ/in.² respectively: the membrane area was 5.2 m.