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Local Liquid Holdups and Hysteresis in a 2-D Packed Bed Using X-ray Radiography

Basavaraj, MG and Gupta, GS and Naveen, K and Rudolph, V and Bali, R (2005) Local Liquid Holdups and Hysteresis in a 2-D Packed Bed Using X-ray Radiography. In: AIChE Journal, 51 (8). pp. 2178-2189.

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Abstract

An X-ray visualization technique has been used for the quantitative determination of local liquid holdups distribution and liquid holdup hysteresis in a nonwetting twodimensional (2-D) packed bed. A medical diagnostic X-ray unit has been used to image the local holdups in a 2-D cold model having a random packing of expanded polystyrene beads. An aqueous barium chloride solution was used as a fluid to achieve good contrast on X-ray images. To quantify the local liquid holdup, a simple calibration technique has been developed that can be used for most of the radiological methods such as gamma ray and neutron radiography. The global value of total liquid holdup, obtained by X-ray method, has been compared with two conventional methods: drainage and tracer response. The X-ray technique, after validation, has been used to visualize and quantify the liquid hysteresis phenomena in a packed bed. The liquid flows in preferred paths or channels that carry droplets/rivulets of increasing size and number as the liquid flow rate is increased. When the flow is reduced, these paths are retained and the higher liquid holdup that persists in these regions leads to the holdup hysteresis effect. Holdup in some regions of the packed bed may be an order of magnitude higher than average at a particular flow rate.

Item Type: Journal Article
Additional Information: The copyright belongs to American Institute of Chemical Engineers.
Keywords: packed bed;x ray;holdups;liquid hysteresis;nonwetting flow
Department/Centre: Division of Mechanical Sciences > Materials Engineering (formerly Metallurgy)
Date Deposited: 22 Aug 2005
Last Modified: 19 Sep 2010 04:19
URI: http://eprints.iisc.ernet.in/id/eprint/3530

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