Mass and momentum transport in extra-luminal flow (ELF) membrane devices for blood oxygenation

In this paper, we report on the characterisation of transport in membrane m odules for blood oxygenation where blood is circulated outside hollow fibre membranes arranged in double layer cross-laid mats at an angle with respec t to the main direction of blood flow. The effect of design and operating v ariables on module performance was investigated with respect to oxygen tran sfer into water, as gaseous oxygen and water are circulated counter-current ly, respectively inside the membrane lumen and through the membrane assembl y. Increasing water flow rates and membrane angles enhanced oxygen transfer ac ross the membrane and resulted in robust operation but also in high pressur e drops. Module pressure drop and oxygen transfer rate were correlated to module geo metry, fibre packing density, water how rate and membrane angle with respec t to the main direction of the liquid Row in non-dimensional equations that can be used by membrane module manufacturers for the design of optimal ELF blood oxygenators. The results suggest that an optimum membrane angle exis ts, beyond which module operation is not convenient in terms of energy. (C) 2001 Elsevier Science B.V. All rights reserved.