Flow of Slurries of Particles with Density Close to That of Water

ABSTRACT The purpose of this work is to investigate the friction factor for slurries of particles with density close to that of water. The use of particles with density close to that of ice aims to get explanations of new generation of liquid-solid coolant in adiabatic conditions. The solid particles are 3mmdiameter polypropylene sphere, of density 869 kg/m. The test section consists of horizontal transparent PVC pipes 22 and 45mm in diameter. Friction losses are measured using differential pressure transducers. Velocity distribution within the water layer is measured using Pitot tube. Flow pattern and particle behaviour are observed using visualisation device. Different flow pattern can be observed in fully turbulent conditions. The transition between the flow pattern depends on the Froude number. Three predicting models of pressure losses in pipe have been used. The first one consists in correlating experimental data using dimensional analysis. The second one uses rheological model: extended Reynolds number based on the empirical Bingham model is introduced. The Blasius law computed by replacing the classical Reynolds number with the extended Reynolds number is found to be applicable to the two-phase flow in its full range. The third one is a two-layer model that contains the effect of pipe diameter. The model treats the flow as being constituted of two layers: a stationary or a moving bed at the top of the pipe and a heterogeneous flow suspension below. The friction coefficient between the bed layer and the pipe is estimated by performing momentum balance using the experimental results (pressure drop, visualisation and distribution of the local velocity within the heterogeneous flow suspension. The validity of the hypothesis of the two-layer model are discussed.