DETERMINATION OF FLUID-TO-PARTICLE HEAT TRANSFER COEFFICIENTS FOR ROTATING PARTICLES

Fluid-to-particle heat transfer coefficients (h fp ) were determined for stationary and rotating potato-alginate cubes heated by carboxymethylcellulose solutions in an aseptic processing system. Fluid temperature, fluid average velocity, CMC concentration, and particle size were varied. In the stationary particle case, the slip generalized Reynolds numbers (Regs) ranged from 1.3 to 6 7. For the rotating particles, Regs ranged from 0.91 to 5.0 and the generalized rotational Reynolds numbers (Re gr ) ranged from 6.0 to 33. The h fp ranged from 120 W/m 2 °C to 2400 W/m 2 °C and from 360 W/m 2 °C to 4300 W/m 2 °C for stationary and rotating particles, respectively. Particle rotation significantly increased h fp . Fluid temperature, particle size, fluid average velocity, and CMC concentration had significant effects on h fp for both stationary and rotating particles. Using Re gs in the dimensionless correlation gave a better prediction of h fp for the rotating particles than using Re gr .

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