Optical techniques for near-wall phenomena in nucleate boiling
Résumé
We report an experimental method consisting of high-speed and high-resolution optical techniques to investigate the near-wall phenomena in nucleate pool boiling. Our focus is on the micrometric liquid layer (microlayer) that can be formed between the wall and the vapor-liquid interface during the bubble growth. We also investigate the wall dewetting dynamics: the dry spot spreading. The installation performs simultaneous and synchronous measurements of the microlayer thickness profile, the wall temperature distribution and the bubble macroscopic shape by white-light interferometry, infrared thermography and sidewise shadowgraphy, respectively, at 4000 frames per second. The novelty is the white light interferometry, which provides precise data on microlayer thickness. The calibration and validation procedures of these optical techniques are discussed along with the post-processing techniques used for image treatment. We also show the results obtained for a nucleate boiling experiment on single bubble growth.
These advanced techniques aim at understanding the fundamental aspects of the near-wall phenomena in nucleate boiling heat transfer, in particular the physics of microlayer formation, its evaporation, the dewetting dynamics and the associated heat transfer. The experimental data can be used to support the development of novel physical models.
Domaines
Physique [physics]Origine | Fichiers produits par l'(les) auteur(s) |
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