Experimental Study of Heating of the Newtonian Suspensions made of Large Hard Spheres Based on the Glucose & Water Solutions Flowing in a Horizontal Duct
Résumé
In this paper we present the results of our research work. The current state of knowledge of Newtonian suspensions of heat flux does not fully understand the problems of flow of charged particles in the Agro-Food Industry. The influence of the hard spheres on the flow was studied. That determines the heat transfer in the mixture. This study highlights the interdependence of the dynamics and thermal of the suspensions of particles with an average diameter (D ≈ 4, 4 mm). Analyses of longitudinal and radial profiles of measured wall temperature permit to verify the convective effects of particles (perturbations of the boundary layer) in flows. Analysis of the heating of these suspensions show that the heat transfer increases with the concentration of particles. The organization of the carrier fluid in monophasic ring surrounding the area of the particles in the center of the pipe is relevant. This fluid ring is linked to the monophasic layer substantially free of particle ("monophasic'' layer). It is harmful because the particles migrate to the cold zone where sterilization is difficult and t his layer due to a layer quasi free particle ("monophasic" layer) that appears on the wall. This phenomenon raises the problem of regular sterilization of the solid liquid suspensions in the Agro Food Industries (AFI). The "effective medium" approach is validated for suspensions of large sized particles. This essential result served to validate the laws of heat transfer typically used for monophasic phase flow and show their implementation in case the two phase approach is made.