2 edition of On the effects of viscoelasticity in stirred tanks found in the catalog.
On the effects of viscoelasticity in stirred tanks
N. GuМ€l OМ€zcan-TasМ§kin
Thesis (Ph.D) - University of Birmingham, School of Chemical Engineering.
|Statement||by N. Gül Özcan-Taşkin.|
Book Outline CRC Press, Book review. Viscoelastic Materials book 1 Introduction: Phenomena Viscoelastic phenomena Transient properties: creep and relaxation Solids and liquids; anelastic materials Dynamic response to sinusoidal load Demonstration of viscoelastic behavior Other works on viscoelasticity Stirred tanks agitated by an eccentrically located angled disc are a simple and cost effective system for laminar mixing applications. V C American Institute of Chemical Engineers AIChE J,
Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing s materials, like water, resist shear flow and strain linearly with time when a stress is applied. Elastic materials strain when stretched and immediately return to their original state once the stress is removed. Roman Grigoriev got his PhD at the California Institute of Technology and became a Research Associate at the University of Chicago before he moved to Georgia Tech. Professor Grigoriev's research on nonequilibrium systems such as fluids, lasers and living systems ranges from mixing in fluids, thin liquid films and wide aperture lasers to the heart muscle.
Dynamic viscoelasticity is the study of linear viscoelastic behavior of a solution, which represents the viscoelasticity of the solution without destroying its structural characteristics. In the dynamic mechanical test, the storage modulus can reflect the elasticity and the loss modulus can reflect the viscosity of viscoelastic fluid. The Effects of Viscoelastic Behavior on Coating 1. THE EFFECTS OF VISCOELASTIC BEHAVIOR ON COATING 2. VISCOELASTICITY • Viscosity (shear rate versus viscosity) • Elasticity (stress and velocity interaction) 3.
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Two major areas of interest of this research have been the effects of viscoelasticity in mechanically agitated vessels and the characterisation of the performance of a relatively new type of impeller in such systems. The mixing of viscous fluids that also exhibit other rheological properties, is commonly carried out in stirred tanks in many.
Mixing viscoelastic fluids is common to many chemical and biochemical process industries where the rheological properties of the bulk change considerably over the time course.
The objectives of this study were to investigate the effects of viscoelasticity in mechanically agitated vessels (on: i- the power consumption and flow patterns in single phase and gassed systems, ii- mixing time under Cited by: 2.
Model viscoelastic fluids prepared exhibited only slight shear thinning properties (Boger fluid type), hence the effects of viscoelasticity could be studied in the absence of other rheological properties.
Results obtained with these fluids were compared to those with viscous Newtonian glycerol covering the transitional flow regime ( Re Cited by: 2. Coating rubber bands is not easy. So when you look at coating liquids that have molecules already formed, or the fluid has a rubbery nature, care needs to be taken to consider the effects of viscoelastic behavior.
Viscoelasticity is the fluid’s reaction to being deformed both in viscosity and elasticity. The influence of polymer additives upon the gas‐liquid mass transfer in stirred tanks is examined.
While the addition of sodium carboxymethyl‐cellulose brings about a reduction of the overall liquid side mass transport coefficient which is in line with the predictions by earlier works, the reduction of k L a in polyacrylamide solutions of equal viscosity is much by: Four general classes of impellers are used in stirred tanks operating at low to medium viscosities in the turbulent regime.
Effects of T ank Size and Impeller. Type,” AIChE J., 43 (2), pp. The impeller Reynolds number for stirred tanks is defined as: (1) Re = ρ N D 2 η, where N is the impeller speed, D is the impeller diameter, ρ is the density, and η is the dynamic viscosity of the fluid.
Depending on the Reynolds number, different flow regimes, i.e., laminar, transitional and turbulent regime occur in tank.
Weheliye Hashi Weheliye, Giovanni Meridiano, Luca Mazzei, Panagiota Angeli, Experimental investigation of the solid-liquid separation in a stirred tank owing to viscoelasticity, Physical Review Fluids, /PhysRevFluids, 5, 6, ().
Whilst viscoelastic fluids have been the subject of much investigation over the years, beginning with Weissenberg׳s observation of rod-climbing phenomena (Weissenberg, ), there has been little in the way of investigation into their effect on processes, although stirred tank geometries are the most well developed area.
Flow visualization studies have been performed with viscoelastic fluids in three-liter and liter stirred tanks. The objectives were to determine the optimum agitator type, impeller diameter, impeller spacing, agitator speed, and feed location to minimize blend time and prevent formation of dead zones in the vessel for the blending of low viscosity materials into a viscoelastic fluid.
The interaction of yield stress and viscoelasticity on the Weissenberg effect. Author links open overlay panel T.P.
Elson 1 J. Solomon A.W. Nienow 2 G.W. Pace. G.C. Papanicolaou, S.P. Zaoutsos, in Creep and Fatigue in Polymer Matrix Composites, Introduction. Viscoelasticity is the property of materials that exhibit both viscous and elastic characteristics when undergoing deformation.
A viscous material exhibits time-dependent behavior when a stress is applied while under constant stress and deforms at a constant rate, and when the load is. The aim of this paper is to study the effect of agitator’s types on the turbulent flows in stirred tanks without and with baffles. The hydrodynamics behavior induced by four different agitator’s types: a Rushton turbine (RT), a circular blade turbine (CBT), a diverging triangular blade turbine (DTBT) and converging triangular blade turbine (CTBT) are numerically predicted by solving the.
High‐accuracy CFD results for laminar flow in a stirred tank agitated by three Rushton turbines are used as a starting point for an in‐depth analysis of mixing. Asymptotic mixing performance is investigated as a function of the Reynolds number by means of Poincaré sections, which reveal large segregated regions with sizes and shapes that.
For Reynolds numbers in the range –10, viscoelastic effects are taken into account up to a Deborah number De of and viscoelasticity and inertia cross-effects are studied.
We examine the effect of breaking spatial symmetry of shear‐thinning viscoplastic fluids in stirred tanks by placing the impeller shaft cm from the centerline. Eccentricity is defined as E = β/ R T where R T is the tank radius and β is the distance from the shaft to the centerline.
The effect of the first normal stress difference, N1, on the vortex sizes and circulation intensities was also examined, with both properties decreasing for increasing N1.
Finally, we observed that the clustering time of the solids in the vessel for viscoelasticity-induced migration was at least three orders of magnitude lower than that.
Viscoelasticity Basic Notions & Examples Formalism for Linear Viscoelasticity Simple Models & Mechanical Analogies Non-linear behavior. Viscoelastic Behavior Generic Viscoelasticity: exhibition of both viscous and elastic properties, depending on the time scale over which an external stress is applied Specific Effects.
Linear viscoelasticity 1. Creep test of a viscoelastic rod A rod of a polymer is held at a constant temperature, stress free, for a long time, so that its length no longer changes with time.
The rod is in a state of equilibrium. At time zero, we attach a weight to the. The effects of weight-average molecular weight (MW) and short and long chain branching on the linear viscoelastic behavior of polyethylene (and ethylene−α-olefin copolymers) are described.
Short chain branching had no effect up to a comonomer (butene) content of wt %. The zero shear viscosity of the linear polyethylenes scaled in the expected manner with MW. This work presents experimental results of the drawdown of floating solids in agitated vessels.
The effect of an agitator type, its location in the tank, and dispersed phase properties on minimum values of agitator speed and power requirements for floating solids suspension was investigated.
The results were processed as dimensionless correlations using the Froude number and .Both harmonic and earthquake-induced ground motions are considered. The response quantities examined are the dynamic wall pressures, the critical forces in the tank wall, and the forces exerted on the foundation.
The effects of tank wall flexibility are studied in a companion paper.Mixing geometries include static mixers [9,10], passive mixer , dough kneaders   , stirred tank reactors , and continuous mixers .