The gravity-driven flashing of metastable water in a pool heated from below : an experimental study
(2023)
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- Authors
- Supervisors
- BARTOSIEWICZ, Yann
- Abstract
- The present research is focused on the gravity-driven flashing of metastable water, a phenomenon which may be encountered in any system being heated from below, where an uprising hot fluid experiences a significant decrease in hydrostatic pressure. For sufficiently large vertical systems, be they a deep pool or some long duct such as a geyser, the temperature of the flowing fluid may exceed its saturation value and reach a so-called superheated, metastable state. From that situation, the metastable liquid may spontaneously vaporize through the form of bubbles as a way to tend toward thermal saturation, a process referred to as flashing. Specifically in this research, the emphasis is put on the case of a water pool heated from below, motivated by the absence in the scientific literature of any known report of the phenomenon in this precise configuration. By means of an experimental device called Aquarius, specifically designed and constructed during this research, the phenomenon is first evidenced in a heated pool. Then, its main characteristics are highlighted: instead of observing a cyclic flashing as for geysers, the emergence of bubbles from the superheated liquid appears typically steady in the presented tests. In addition, those created bubbles do emerge within the liquid bulk itself, into the most superheated area of the pool: underneath the liquid free surface. The dependence of the bubble production process on the heating power, operating pressure, initial pool level and amount of dissolved gases in the pool is then investigated. At last, an experimental data reduction by means of a set of mathematical correlations is achieved and a simple thermodynamic modeling of the studied system is proposed.
- Affiliations
Citations
Martin, J. (2023). The gravity-driven flashing of metastable water in a pool heated from below : an experimental study. https://hdl.handle.net/2078.5/104101