MASS-TRANSFER IN VARIOUS HOLLOW FIBER GEOMETRIES

Mass transfer coefficients in commercial modules, including blood oxygenators, agree with literature correlations at high flows but are smaller at low flows. The smaller values at low flows probably result from channelling in the hollow fiber bundle. For the special case of flow within the fibers, the slight polydispersity of the hollow fibers causing this channelling can be used to predict deviations from the Leveque limit. These deviations can not be predicted from extensions to the Leveque analysis, or the analysis by Graetz. For the special case of flow outside the fibers, the mass transfer coefficients in commercial modules of various geometries are surprisingly similar, and fall below those of carefully hand-made modules. These results can be used to develop still better membrane module designs.