Abstract

In order to enhance heat transfer from a heated surface to a granular material, the surface is sometimes subject to vibration with the expectation that the oscillations will promote material renewal at the surface and result in increased heat transfer to the bed. Indeed, previous studies have shown that depending on the vibration parameters and bed depth, the bed of material will exhibit a variety of dynamic phenomena including side wall convection cells, surface waves, and kink waves; all of which influence the motion of particles within the bed. This paper investigates the time-averaged heat transfer coefficient from a vertically-vibrated, heated plate to a deep bed of granular material over a range of oscillation parameters. An experimental apparatus was designed consisting of a narrow plexiglass container with a heated copper base embedded in a Delrin jacket. The container was partially filled with soda lime glass spheres and mounted on an electromagnetic shaker which provided the vertical, sinusoidal oscillations with controllable amplitude and frequency. The resulting heat transfer coefficient measurements are presented as a function of the oscillation parameters for oscillation frequencies between 15–60 Hz and oscillation acceleration amplitudes between 0 and approximately 7.0g where g is the acceleration due to gravity. The steady state heat transfer coefficient is found to increase over 300% for an acceleration amplitude between one and two g.

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