Flow Structures of a Liquid Film Falling on Horizontal Tubes

• Published in: Chemical engineering & technology 2005-06, Vol.28 (6), p.684-694
• Main Author: Mitrovic, J.
• Format: Article
• Language: English
• Subjects: Applied sciences; Chemical engineering; Exact sciences and technology; Flow behavior; Hydrodynamics of contact apparatus; Liquid films; Tubes
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.200500064

Patterns of a liquid film falling across a vertical array of horizontal tubes change from droplet mode at low flow rates to liquid sheet at high flow rates. Between these limits, liquid columns form as a further stable flow pattern. The transition from one flow mode to another occurs via unstable structures consisting simultaneously of droplets and columns or of merging columns. The boundaries of the flow modes can be obtained from relationships expressing the flow rate as a function of physical properties, that is, the Reynolds number as a function of the Kapitza number. Correlations for the pattern boundaries recommended in the literature are compared with each other and found to be in acceptable agreement for practical purposes. Transitions between flow modes of a liquid film falling across a vertical array of horizontal tubes occur with changing flow rates. The boundaries of the flow modes can be obtained from relationships expressing the flow rate as a function of physical properties. Correlations for the pattern boundaries recommended in the literature are compared with each other and found to be in acceptable agreement for practical purposes.