Abstract

When a suspension of particles in a shear thinning fluid is pumped in a pipeline, friction losses differ from those where the carrier fluid is Newtonian. In this paper, the results of an experimental study of the friction losses generated in a circular pipe due to the laminar flow of a mixture of a pseudoplastic fluid and solid particles are presented. The experiments were carried out in a closed loop with a transparent test section 12 m long and 2 inches diameter. The shear thinning fluids corresponded to solutions of CMC in water at various concentrations. The rheology of the mixtures showed flow indexes between 0.42 and 0.83, and consistency coefficients in the range 0.13 to 3.34 Pa∙sn. Three groups of glass beads were used as solid particles, with mean diameters equal to 120, 300 and 600 µm. The criterion by Mishra and Tripathi (1971) was used to define the flow regime. Using the Metzner-Reed (1955) definition of the Reynolds number, it is verified that all the experiments were made within laminar flow. The results indicate that the friction factor of the mixture can be expressed in terms of the friction factor of the pseudoplastic fluid (without particles) plus a correction that depends on the solid concentration relative to the packing concentration , the flow Reynolds number, the particle Reynolds number, and the Archimedes number. The experimental results show a very good collapse with the proposed empirical correlation.