TY - JOUR
T1 - Angular segregation of fibres in pipe flow
T2 - floc formation and utilization for length-based fibre separation
AU - Redlinger-Pohn, Jakob D.
PY - 2020/9/1
Y1 - 2020/9/1
N2 - Cellulose fibres are prone to flocculate and form aggregates that are deformable by the hydrodynamic stress. In this work I document for coiled pipe flow, known to have secondary motion in the pipe cross-sectional plane, an accumulation of fibre flocs and fibre aggregates at the outer bend. That is the segregation into a section in the pipe cross-section and hence presents a case of angular segregation. The segregation was studied for non-coherent crowded fibre flocs. For that, segregation benefited from fibre concentration and suffered from increased hydrodynamic stress expressed by increasing Reynolds number. Based on the observed segregation of fibres a flow splitter was designed that separated the flow at 1/3 of the tube diameter measured from the inner bend. The outer bend suspension length-weighted fibre length was found to increase. For the best case in this work, the difference between outer and inner bend relative to the feed fibre length was 22%. As for radial and axial segregation, which are known, also angular segregation is fibre-length sensitive. As such it can be exploited for length fractionation of networking and aggregating elongated particles, for example fibres.
AB - Cellulose fibres are prone to flocculate and form aggregates that are deformable by the hydrodynamic stress. In this work I document for coiled pipe flow, known to have secondary motion in the pipe cross-sectional plane, an accumulation of fibre flocs and fibre aggregates at the outer bend. That is the segregation into a section in the pipe cross-section and hence presents a case of angular segregation. The segregation was studied for non-coherent crowded fibre flocs. For that, segregation benefited from fibre concentration and suffered from increased hydrodynamic stress expressed by increasing Reynolds number. Based on the observed segregation of fibres a flow splitter was designed that separated the flow at 1/3 of the tube diameter measured from the inner bend. The outer bend suspension length-weighted fibre length was found to increase. For the best case in this work, the difference between outer and inner bend relative to the feed fibre length was 22%. As for radial and axial segregation, which are known, also angular segregation is fibre-length sensitive. As such it can be exploited for length fractionation of networking and aggregating elongated particles, for example fibres.
KW - Coiled flow
KW - Fibre segregation
KW - Flocculation
KW - Fractionation
KW - Length-based fibre separation
KW - Size separation
UR - http://www.scopus.com/inward/record.url?scp=85087494069&partnerID=8YFLogxK
U2 - 10.1007/s10570-020-03290-8
DO - 10.1007/s10570-020-03290-8
M3 - Article
AN - SCOPUS:85087494069
SN - 0969-0239
VL - 27
SP - 7431
EP - 7446
JO - Cellulose
JF - Cellulose
IS - 13
ER -