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Item type:Publication, Access status: without files , Reaktive Absorption von Kohlenstoffdioxid in helikalen Hohlfasermembrankontaktoren [Chemical absorption of CO2 in helically wound hollow fiber membrane contactors](Wiley-VCH, 2013-03-06); ; ; ; 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 dimen-sionless Dean number absorption rates for both straight and helically shaped hollow fibers have been successfully predicted. © 2013 Wiley-VCH Verlag GmbH & Co. KGaA.Publicationtype: Journal Article126 - Some of the metrics are blocked by yourconsent settings
Item type:Publication, Access status: without files , Laminares Mischen in Miniatur-Hohlfasermembranreaktoren durch Ausnutzung von Sekundärströmungen (Teil 1)(Wiley-VCH, 2011-06-22); ; ; ; Miniaturization is a method of allowing defined reaction conditions in modern process engineering. It also allows a continuous operation mode, short diffusion paths and control of shear stress. An unfavorable consequence of miniaturization is the use of small flow rates and ineffective laminar mixing. Regarding processes that are well known in macro scale, problems arise when they are transferred to micro scale. In micro scale, transport mechanisms in boundary layers play a major role, but are widely unknown. Miniature hollow-fiber membrane reactors (mini HFMR) are developed to aim a defined adjustment of process parameters. Their conceptual characteristics are indirect aeration, integrated educt feed and product removal and controlled shear rate. Because secondary flows are appropriate to enhance mixing [1], their principles will be applied to the mini HFMR. Dean vortices on one side and the von Kármán vortex street on the other are applied to enhance the transport between membrane and liquid flow. To work straightforward, first numerical simulations are performed. Later on the results of the simulations will be validated by experiments. Based on two different reactor types it will be shown that secondary flows enhance the mass transfer significantly while keeping the shear stress low. This way miniaturization turns out to be an all appropriate method for various fields of bio process engineering. © 2011 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.Publicationtype: Journal Article20