Rheological Properties of Noncohesive Apple Dispersion With Helical and Vane Impellers: Effect of Concentration and Particle Size

The proportionality constant, ks, 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 ηc and yield stress σOC were also calculated. The magnitudes of K increased and of n decreased with increase in pulp concentration. Experimental values of the vane yield stress, σOν, measured with a six‐blade vane increased with increase in pulp content. The values of σOC obtained using the Casson model were close to the experimental values σOν. The effect of particle size on the relative viscosity, ηr, was correlated with Peclet number.