Question

Hemodialysis is performed using a dialysis cartridge containing 100 hollow membrane fibers as shown below to get rid of urea from the blood. Blood is pumped (0.25 litres/min, Urea concentration 5mM) to the inside of the fibers while dialysis solution is pumped on the outside as shown below. The diameter of each fiber in the cartridge is approximately 4 mm. The concentration of urea in the blood exiting the cartridge and subsequently returned to the patient needs to be 2mM. Calculate the length of the hollow fibers required for this process at steady state. State all assumptions. The permeance PM of the membrane is 8.73x10-6 m/s. The mass transfer coefficient on the blood side is estimated to be kc1= 1.25x10-5 m/s and that on the dialysis solution side as kc2=3.33x10-5 m/s.

1). Hemodialysis is performed using a dialysis cartridge containing 100 hollow membrane fibers as shown below to get rid of urea from the blood. Blood is pumped (0.25 litres/min, Urea concentration 5mM) to the inside of the fibers while dialysis solution is pumped on the outside as shown below. The diameter of each fiber in the cartridge is approximately 4 mm. The concentration of urea in the blood exiting the cartridge and subsequently returned to the patient needs to be 2mM. Calculate the length of the hollow fibers required for this process at steady state. State all assumptions. The permeance PM of the membrane is 8.73x106 m/s. The mass transfer coefficient on the blood side is estimated to be kc1-1.25x10-5 m/s and that on the dialysis solution side as ke2-3.33x10-5m/s. Blood Flow rate from patient 0.25 litres/min Dialysis solution to drain Fibers -Jacket Dialysis solution from hemodialysis machine Blood back to patient

Answer 1

3 -9 ms ←s. -5

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