Variations of buoyancy-induced mass flux from single-phase to two-phase flow in a vertical porous tube with constant heat flux
- Hong Kong Univ. of Science and Technology, Kowloon (Hong Kong). Dept. of Mechanical Engineering
Buoyancy-induced convective fluid flow with and without phase-change heat transfer in a porous medium is frequently encountered in numerous important technological applications. Examples include thermal energy storage, nuclear waste isolation, geothermal systems, porous medium heat pipes, food drying, porous insulation moisture transport, and post-accident analysis of liquid-cooled nuclear reactors, electronic cooling, etc. This paper presents an experimental study of a buoyancy-induced flow of water with phase-change heat transfer in a vertical porous tube heated at a constant heat flux. Experiments were carried out from subcooled liquid flow to convective boiling by varying the imposed heat fluxes. At a prescribed heat flux the steady-state mass flux of water, as well as the temperatures along the tube wall and along the centerline of the packed tube, were measured. It is shown that for both single-phase flow and the two-phase flow with a rather low vapor fraction, the induced mass flux increased as the heat flux was increased. However, as the imposed heat flux was increased further, the induced mass flux dropped drastically, and remained relatively constant afterwards. The influences of various parameters such as the porous tube diameter, the particle sizes, and the hydrostatic head on the induced mass flux are also examined.
- Sponsoring Organization:
- USDOE
- OSTI ID:
- 687529
- Journal Information:
- Journal of Heat Transfer, Vol. 121, Issue 3; Other Information: PBD: Aug 1999
- Country of Publication:
- United States
- Language:
- English
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