RHEOLOGICAL PROPERTIES OF NONCOHESIVE APPLE DISPERSION WITH HELICAL AND VANE IMPELLERS: EFFECT OF CONCENTRATION AND PARTICLE SIZE

Abstract

ABSTRACT The proportionality constant, k s , between shear rate, γ, and agitation velocity, N, for a helical ribbon‐screw (HRS) agitator was 17.8. Using the HRS agitator, values of consistency index K and the flow behavior index n of 14 apple pulp suspensions at seven different solids concentrations and two average particle diameters 0.71 mm and 1.21 mm were determined; in addition, values of the Casson viscosity η c and yield stress σ OC were also calculated. The magnitudes of K increased and of n decreased with increase in pulp concentration. Experimental values of the vane yield stress, σ Oν , measured with a six‐blade vane increased with increase in pulp content. The values of σ OC obtained using the Casson model were close to the experimental values σ Oν . The effect of particle size on the relative viscosity, η r , was correlated with Peclet number.