Two-phase distribution in the vertical flow line of a domestic wet central heating system

Fsadni, A.M. orcid iconORCID: 0000-0003-3047-2714 and Ge, Y.T. (2013) Two-phase distribution in the vertical flow line of a domestic wet central heating system. In: Experimental Fuild Mechanics, Hradec Kralove, Czech Republic.

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Official URL: http://dx.doi.org/10.1051/epjconf/20134501030

Abstract

The theoretical and experimental aspects of bubble distribution in bubbly two-phase flow are reviewed in the context of the micro bubbles present in a domestic gas fired wet central heating system. The latter systems are mostly operated through the circulation of heated standard tap water through a closed loop circuit which often results in water supersaturated with dissolved air. This leads to micro bubble nucleation at the primary heat exchanger wall, followed by detachment along the flow. Consequently, a bubbly two-phase flow characterises the flow line of such systems. The two-phase distribution across the vertical and horizontal pipes was measured through a consideration of the volumetric void fraction, quantified through photographic techniques. The bubble distribution in the vertical pipe in down flow conditions was measured to be quasi-homogenous across the pipe section with a negligible reduction in the void fraction at close proximity to the pipe wall. Such a reduction was more evident at lower bulk fluid velocities.


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