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Sonderseminar SFB 985:
"Funktionelle Mikrogele & Mikrogelsysteme"

Prof. Ruud van der Sman
Food & Biobased Research, Wageningen University, the Netherlands

begin
18.Mar.2014 10:30
end
18.Mar.2014 11:30
venue
Seminarraum A1-A3, Building 04.6

Microfiltration of bidisperse suspensions: from effective temperature theory to beer clarification applications

Abstract:

Our lab is involved in both theoretical work on confined, sheared suspensions and its application in practical microfiltration problems. Our research is motivated by the aim of fractionation of multicomponent food streams like milk into their constituent components. Crossflow membrane microfiltration has been our classical workhorse for that.

In microfiltration shear-induced diffusion is the dominant physical process for the growth of a cake layer above the membrane. Theory for shear-induced diffusion for monodisperse suspensions exists already for two decades. However, at the start of our research a physical theory for bidisperse suspensions was still absent. We have reformulated the theory of monodisperse suspensions into a theory using a non-equilibrium osmotic pressure as a driving force, using an effective temperature linear in the viscous stress [1]. With help of this concept we have been able to formulate the theory for bidisperse suspensions, and have shown it predicts quite well the non-uniform particle concentration profiles in confined microchannel flow [2].

 The theory has also been applied to the problem of beer microfiltration [3]. Non-clarified beer consists of yeast cells and aggregates of polyphenols and proteins, which differ one order of magnitude in size, and are subject to shear-induced diffusion. We will present some analysis of experiments by means of our simulation model.

 

[1] H. M. Vollebregt, R. G. M. van der Sman, and R. M. Boom. 
Suspension of modelling in particle migration and microfiltration. 
SOFT MATTER, 6(24):6052--6064, 2010.

[2] H.M. Vollebregt, R.G.M. van der Sman, and R.M. Boom. 
Model for particle migration in bidisperse suspensions by use of effective temperature.
Faraday Discussions, 158:89, 2012.

R.G.M. van der Sman and H.M. Vollebregt. 
Effective temperature for sheared suspensions: a route towards closures for migration in bidisperse suspension. 
Adv. Coll. Interface Sci., 138-139:1, 2012.

 [3] R.G.M. van der Sman and H.M. Vollebregt. 
Transient critical flux due to coupling of fouling mechanisms during crossflow microfiltration of beer.
Journal of Membrane Science, pages 21{37, 2013.

Contact

Prof. Dr. Gerhard Naegele
Phone: +49 2461 61-2504
Fax: +49 2461 61-2280
email: g.naegele@fz-juelich.de

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