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ISSN Online: 2377-424X

ISBN Print: 978-1-56700-421-2

International Heat Transfer Conference 15
August, 10-15, 2014, Kyoto, Japan

Effect of Velocity and Evaporation on Non-IsoThermal Meniscus in a Capillary

Get access (open in a dialog) DOI: 10.1615/IHTC15.mtr.009185
pages 5149-5163

Abstract

The problem of bubble displacement into confined spaces such as Hele-Shaw cells in capillary tubes has been addressed for over half a century now, starting with Saffman and Taylor (1958) and Bretherton (1961). The subject has recently gained another interest, as attempts are made to model the behavior of the Pulsating Heat Pipe (PHP). This fairly new heat transfer device uses bubble oscillations to transfer large heat fluxes with excellent thermal performance. However, many physical phenomena influence these oscillations, making these devices difficult to model accurately. This work is a contribution to understand even more such phenomena. To do so, we consider an axisymmetric vapor bubble translating at a constant velocity in a capillary tube filled with liquid and heated with a constant heat flux, generating evaporation at the liquid-vapor interface. An asymptotic expansion according to the capillary number (raised to the power of third) is performed. Criteria for the dry-out and the film thickness at the matching point between the meniscus and the deposited thin film are determined at the leading order as function of the bubble velocity and the heat flux load, among other parameters. The present analysis is therefore a generalization of the well-known Park and Homsy result, h0/a = 1.337Ca^(2/3) (where h0 is the thickness of the thin film deposited by – and just behind – the meniscus advancing in a capillary tube of radius a), to non-isothermal case by introducing the effect of the applied heat load in the calculation of the liquid-vapor interface position.