Steady-State Simulations of Liquid−Particle Food Flow in a Vertical Pipe

Abstract

Steady-state two-dimensional flow of food containing a liquid and particle mixture in a vertical pipe was simulated using the Lagrangian approach. The Fluent 5.4 computational fluid dynamic program was modified for liquid−particle food flow with the aid of user-defined subroutines and used in this simulation. The particle velocity profile and particle residence time were calculated at the outlet of the vertical pipe. The calculated results were compared with the experimental data of Lareo et al. (Powder Technol. 1997, 93, 23). Good agreement between calculation and experimental data indicates that numerical modeling has a good potential to predict the particle residence time and particle velocity profile, and, in turn, results in the potential reduction of costly experimentation in the food industry.

Effects of Particle Diameter and Position on Hydrodynamics around a Confined Sphere

“…In the particle force balance equation, expressions for drag and lift coefficient on the particle are required to describe its motion . Unluturk and Arastoopour numerically simulated single particle velocity profile in a pipe based on the experimental study of Lareo et al Tracer particles 9 mm in diameter were injected one at a time into a vertical tube of diameter 44 mm. This translates into a significant blockage ratio of BR = 0.21.…”

“…The simulation results were found to overpredict the velocity of the particles in the tube, and these were closer to the continuous phase velocity profile. Unluturk and Arastoopour used a carboxy methyl cellulose (CMC) solution as the carrier phase, which was found to obey the Ellis model.…”

“…In the Lagrangian particle tracking, where the particles are tracked for their position, velocity, and residence time, accurate expressions for drag and lift forces acting on the particles are required that take into account the particle’s diameter, relative to the tube, as well as it is position relative to the tube axis. Unluturk and Arastoopour estimated, through simulations, the residence times of spherical particles suspended in a 0.3% CMC solution flowing through a tube. They used drag coefficient correlations that were only functions of the Reynolds numbers.…”

“…This may constrain accurate design of industrially important processes. One important example is in the field of aseptic food processing, where the relatively slow-to-heat food particles are sterilized by heating the carrier fluid inside a holding tube. − In these applications, the kinetic parameter of microbial destruction is highly sensitive to temperature. Variations in heating duration and heating rate of the particle may significantly affect the outlet product sterility.…”