Passage time distributions for high solid fraction solid-liquid food mixtures in horizontal flow: unimodal size particle distributions

The how of two phase, high solid concentration solid-liquid food mixtures is important in many food engineering operations. Prediction of the length of time spent by solid particles in holding tube flow is of vital importance for ensuring sterility and optimising product quality. Experimental work has been performed in solid-liquid flows with solids concentrations up to 55% v/v, with 5 or 10 mm spherical particles (0.1 < d* < 0.22), in different viscosity carrier fluids (0.3%, 0.5% and 0.8% w/w CMC). Particle passage times were measured visually and by Hall effect sensors, four different distributions were found at different solid concentrations and particle diameter corresponding to different patterns of particle flow. Data for the minimum, mean and maximum passage times are also expressed. When a region of slow moving particles existed near the tube wall, minimum passage times were found to be smaller because of channelling. (C) 1999 Elsevier Science Ltd. All rights reserved.