Measurement of hollow fiber membrane permeance in a gas-liquid environment

The primary goal of the research for this thesis was to develop and test a methodology for measuring the gas permeance of hollow fiber membranes (HFM) in a gas-liquid environment (gas phase inside membrane wall, liquid phase outside). Interest in such a methodology was generated by the development of a high efficiency HFM blood oxygenation device for which gas exchange capacity is potentially limited by membrane permeance, both acutely and chronically. A gas-liquid permeance measurement apparatus and methodology were developed and used to measure the oxygen and carbon dioxide permeance of three different hydrophobic microporous HFMs and four different polymer coated, or composite, HFMs all of which encompassed a wide range of permeance levels. The gas-liquid permeance measurements were compared with measurements made in a gas-gas environment to validate the methodology and to determine whether the permeance of a HFM in a gas-liquid environment is inherently different than in a gas-gas environment.; The methodology was based on measuring the overall system permeability for a range of liquid velocities and isolating the membrane resistance to gas flux from the liquid boundary layer resistance by regression of a nonlinear system model to the data. The success of the methodology in accurately estimating membrane permeance was found to depend on the maximum liquid velocity which the system could consistently generate past the fibers. It was conclusively shown for composite fibers with permeances less than these values, that the gas-liquid permeance was equal to the gas-gas permeance. The evidence suggested the same conclusion for high permeance microporous and coated fibers although this could not be demonstrated by exact measurements.; The methodology proved valuable for studying the long term permeance of HFMs in contact with blood. Such effects are difficult or impossible to study using gas-gas permeance measurements. Accordingly, the methodology was used to evaluate the potential role of condensation in the occurrence of plasma leakage, and the effect of cell free hemoglobin molecules on the boundary layer mass transfer coefficient of blood flowing over HFMs.