Chemical Absorption of CO2 in Helically Wound Hollow Fiber Membrane Contactors Hollow fiber membrane contactors have been already tested for the physical and chemical absorption of CO2. Due to their large surface to volume ratio contactors are a promising alternative to conventional equipment. Nevertheless, the overall mass transport in commercially available modules is limited. Due to the small inner diameters of the fibers and the respective low cross flow velocities only low Reynolds numbers can be realized, which leads to a laminar flow regime. In this study Dean vortices have been generated to enhance the mass transport in the boundary layer. Also the influence of the helical curvature diameters on the absorption performance has been studied. By means of the film theory and the dimensionless Dean number absorption rates for both straight and helically shaped hollow fibers have been successfully predicted.