Effect of shear rate on aggregate size and structure in the process of aggregation and at steady state

0384987 - ÚH 2013 RIV CH eng J - Journal Article
Bubáková, Petra - Pivokonský, Martin - Filip, Petr
Effect of shear rate on aggregate size and structure in the process of aggregation and at steady state.
Powder Technology. Roč. 235, February (2013), s. 540-549. ISSN 0032-5910. E-ISSN 1873-328X
R&D Projects: GA ČR GAP105/11/0247
Institutional support: RVO:67985874
Keywords : aggregation * aggregate size * fractal dimension * shear rate * steady state * time evolution
OECD category: Fluids and plasma physics (including surface physics)
Impact factor: 2.269, year: 2013
Method of publishing: Limited access
https://www.sciencedirect.com/science/article/pii/S0032591012007632?via%3Dihub

The paper deals with the dependence of aggregate properties on the shear rate (G) in the aggregation process and at steady state. Natural raw water and ferric sulphate were aggregated in a Taylor–Couette reactor. The methods of image and fractal analysis were used to determine the aggregate size and structure. It was observed that at the early phase of aggregation, the aggregate growth rate is higher for lower shear rates. At G≤150 s⁻¹, the time aggregation curve contains the local maximum before reaching the steady state. Moreover, the different extent of break-up and restructuring was proved for different values of shear rate. At G≥200 s⁻¹, the aggregation curve misses the local extreme completely. Itwas found thatwith increasing shear rate (G=21.2–347.9 s⁻¹), the aggregates are smaller (d=1504–56 μm),more compact (D₂=1.54–1.91) and more regular (D_pf=1.37–1.10). A relationship for the description of dependence of fractal dimension on the shear rate was also suggested.
Permanent Link: http://hdl.handle.net/11104/0214414