Abstract
Convective heat transfer coefficients were evaluated during end-over-end rotation processing of cans filled with liquid and particle mixtures in a pilot-scale, overpressure water-immersion, rotary retort. Two modes of end-over-end agitation were employed, one involving a continuous and the other involving an oscillatory rotation of the cage containing cans. Nylon spheres of diameter 0.025 m were used as test particles and a high temperature bath oil was used as the test liquid. A lumped capacity approach was employed to determine the overall heat transfer coefficient, U, and an inverse heat transfer approach was used to determined the fluid to particle heat transfer coefficient, h fp. Effects of the two modes of rotation (continuous and oscillation) on the associated heat transfer coefficients were evaluated at three speeds (8, 16 and 24 rpm) and three radii of rotation (0,13 and 26 cm). An analysis of variance showed that the effects of rotation speed and mode of rotation on both U and h tp were significant (p < 0.05). However, the effect of radius of rotation was significant only with U. These factors also affected the calculated process times for achieving an accumulated lethality (F o) of 10 min at the particle center and in the can liquid in a similar fashion. In general, U and h fp values associated with continuous rotation were 10-40% higher than those associated with oscillatory rotation.
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