A mass transfer device including a hollow fiber bundle wound on a core for radially outward flow of a first fluid. The core has an axis extending from one end to the other. The hollow fiber bundle has packing fractions which increase radially outward of the core's axis for a major portion of the bundle....http://www.google.de/patents/US5462619?utm_source=gb-gplus-sharePatent US5462619 - Mass transfer device having a hollow fiber bundle
