PARTICLE-VELOCITY PROFILES FOR SOLID-LIQUID FOOD FLOWS IN VERTICAL PIPES .1. SINGLE PARTICLES

Many food processing operations involve the flow of solid-liquid mixtu res, often with simultaneous heat transfer. Prediction of the effects of processing requires understanding of the heat transfer and flow pro perties of the two phases. The fluid mechanics literature contains muc h information on the radial migration of particles in vertical how, bu t it is not certain how this might apply to food processing. A series of experiments has been carried out to study the behaviour of single f ood simulant particles (5-10 mm) in carboxymethyl cellulose (CMC) solu tions, in 44 mm vertical pipes, to study whether migration occurs. Res ults confirm that migration can be significant in laminar flows of foo d fluids: effects are greater for larger particles of high density flo wing in low viscosity fluids.