The effect of Dean Flow in a tube flow fractionation device
Lukas Jagiello, Jakob Redlinger-Pohn, Wolfgang Fischer, Rene Eckhart and Wolfgang Bauer, Graz University of Technology, Graz, Austria
Fractionation in laboratory scale is a common way to evaluate size distributions of pulp samples. The method of interest in the present study, is the Tube Flow Fractionation (TFF) device. This device separates pulp samples according to their particle size based on the flow regime inside the tube. Longer particles such as fibres are dragged with the faster middle flow and concentrate at the front end of the flowing column. Smaller particles and fines are concentrated at the end of the flow. In the current work, a TFF similar to those described in the literature was set up to investigate the effect of secondary flow (Dean Flow) in the flow regime of a coiled tube on the fractionation performance. Centrifugal forces acting on the fluid generate a pressure difference between the inner and outer bend of the tube. This pressure difference in turn leads to the formation of a secondary flow. Based on a simple design of the tube flow fractionator, settings such as flow velocity or the curvature can be easily adjusted. Trials based on different pulp samples as well as fractions of these pulps show the influence of secondary flow on the fractionation performance in the tube flow.
Nordic Pulp & Paper Research Journal (NPPRJ) is an international scientific magazine covering science and technology for the areas of wood or bio-mass constituents, pulp and paper and including new fiber-based materials, recovery and by-products from pulping processes, bio-refining and energy issues. Articles meeting required scientific standards are accepted from any continent. Open Access: Articles not available through Gold Open Access may be purchased by credit card as a pdf file, to be downloaded within 24 h after ordering, at a price of 22 EUR per article. (Value added tax may apply depending on your location, which you enter at payment logout.) Such articles have Green Open Access, i.e. authors may share articles on their personal non-commerical homepage immediately after publication on the website and download them to non-commercial hosting platforms one year after publication in a full issue of NPPRJ. ISSN: 0283-2631