Bubbly-intermittent flow transition in helically coiled tubes

Li, Z, Jiang, S, Yang, X, Huang, Y, Zhu, G, Tu, J and Zhu, H 2017, 'Bubbly-intermittent flow transition in helically coiled tubes', Chemical Engineering Journal, vol. 323, pp. 96-104.

Document type: Journal Article
Collection: Journal Articles

Title Bubbly-intermittent flow transition in helically coiled tubes
Author(s) Li, Z
Jiang, S
Yang, X
Huang, Y
Zhu, G
Tu, J
Zhu, H
Year 2017
Journal name Chemical Engineering Journal
Volume number 323
Start page 96
End page 104
Total pages 9
Publisher Elsevier BV
Abstract This paper experimentally investigated the bubbly-intermittent flow (BI) transition in helically coiled tubes (HCT) with coil diameter of 20, 40 and 80 cm. A double sensor conductivity probe and a high-speed camera were used to obtain local phase distribution parameters and flow imagery. Because of the centrifugal force, buoyancy was redirected and enhanced, leading to a highly asymmetry and concentrated bubble distribution. As a result, BI transitions occurred at much lower gas flow rates in HCTs. Observation of the BI transition revealed two mechanisms: bubble accumulation in flow direction due to bubble velocity difference (liquid superficial velocity lower than 1.5 m/s), and bubble accumulation in radial and peripheral direction due to strong buoyancy (liquid superficial velocity higher than 1.5 m/s). The critical void fraction at which BI transition occurred (e.g., α = 0.065 for coil diameter of 40 cm) increased as the coil diameter increased, and was much lower than that of straight tubes (α = 0.25-0.51). A correlation predicting BI transition was established, covering both straight inclined tubes and HCTs; which met the experimental results well when the coil diameter was larger than 0.2 m.
Subject Philosophy and Religious Studies not elsewhere classified
Keyword(s) Bubbly flow
Centrifugal force
Flow regime transition
Helically coiled tube
Intermittent flow
DOI - identifier 10.1016/j.cej.2017.04.029
Copyright notice © 2017 Elsevier B.V. All rights reserved.
ISSN 1385-8947
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