Using CFD to simulate heat transfer in particle curtains

Afshar, Sepideh, and Sheehan, Madoc (2012) Using CFD to simulate heat transfer in particle curtains. In: Ninth International Conference on CFD in the Minerals and Process Industries. pp. 1-7. From: Ninth International Conference on CFD in the Minerals and Process Industries, 10-12 December 2012, Melbourne, Australia.

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Abstract

Particle curtains are very common in industrial drying, particularly in the minerals industry. Flighted rotary dryers are typical industrial unit operations in which particle curtains interact with hot air and undergo both convection and evaporation. Furthermore, there are many examples within industrial processing where streams of hot particles could be used to extract or reclaim energy. However, our understanding of heat transfer in falling curtains is limited by the complexity of curtain behaviour in comparison to the behaviour of single particles. Falling curtains exhibit convergent and divergent behaviour depending on inlet conditions and particle properties. The initial thickness of a curtain at discharge and the curtain flow rate have significant effects on the shapes of falling curtains and lead to varying rates of convective heat ransfer. In this work 3-D Eulerian-Eulerian CFD is used to simulate convective heat transfer in free falling particle curtains. Total heat loss for curtaining particles falling a fixed distance is compared to heat loss for isolated single particles. Hot spherical silica particles with density of 2634 kg/m3 at 400K (200 μm, 400 μm and 600μm) flow at approximately 0.041 kg/s to 0.2 kg/s through a narrow slot in a rectangular box (0.45m×0.9m×0.225 m) filled with ambient air. The slot sizes through which the particles enter the rectangular box were 10mm, 30mm, 60mm and 80mm. Mesh dependency was performed by comparing the average properties of the falling curtain such as total heat loss per unit mass, as a function of mesh size. Mesh dependency was found to be independent of convergence and divergence of particle curtains and a 4mm mesh size was selected. The results for total heat loss at different slot sizes in the particle curtain simulations were compared to commonly used single particle heat transfer models. The results showed that modifying the inlet slot width at 0.041kg/s for 400μm particles can lead to 13% increases in rates of convective heat transfer per unit mass.

Item ID: 26338
Item Type: Conference Item (Research - E1)
ISBN: 978-1-922173-01-0
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Date Deposited: 12 Apr 2013 06:17
FoR Codes: 09 ENGINEERING > 0915 Interdisciplinary Engineering > 091503 Engineering Practice @ 33%
09 ENGINEERING > 0915 Interdisciplinary Engineering > 091599 Interdisciplinary Engineering not elsewhere classified @ 34%
09 ENGINEERING > 0915 Interdisciplinary Engineering > 091504 Fluidisation and Fluid Mechanics @ 33%
SEO Codes: 85 ENERGY > 8507 Energy Conservation and Efficiency > 850703 Industrial Energy Conservation and Efficiency @ 100%
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