CE30 - Physique de la matière condensée et de la matière diluée

Cavitation under extreme heat transfer – CASTEX

Submission summary

Liquid boiling is an out-of-equilibrium phase change phenomenon which is at the center of the technology of heat exchangers. Two types of boliling phenomena can happen: nucleate boiling occurs when a liquid is heated just above its normal boiling point (100 degrees Celsius for water) and explosive boiling corresponds to the crossing of the liquid/vapor spinodal line (300 degrees Celsius for water). Explosive boiling is at the origin of accidents in nuclear power plants and understanding its physics is therefore of primary importance to prevent such accidents. Explosive boiling can be triggered at the nanoscale by metallic nanoparticles in a liquid environment when they are irradiated by intense laser pulses. These experiments cannot be interpreted in the frame of classical nucleation theories, due to the different nanoscale energy effects that control small-scale boiling. In particular, near-field thermal radiation through the vapor nanobubble should play a leading role but this effect has been poorly characterized for an illuminated nano-object in a liquid/vapor environment.
The objective of the Castex project is to investigate the transition between explosive boiling and nucleate boiling by means of a combination of experimental observations and numerical modelling. To span the transition, we will successively consider nano-objects of various shapes and aggregates composed of nanoparticles that should enhance the transition to nucleate boiling as a result of their extended spatial dimensions. In particular, we will focus on the effect of the liquid environment and of near-field thermal radiation, which is strongly enhanced at the nanoscale. To reach this objective, the project gathers french experts in nano-optics, cavitation, liquid-state physics, and heat transfer at small scales. Specifically, the transition from explosive to nucleate boiling will be investigated based on the development of a phase field model, which yields already good description of the physics of boiling around small nanoparticles as observed experimentally. To explore boiling around different nanoparticle geometries, the ILM1 team will developed a 3D version of the code that will account for near-field thermal radiation that takes place between the hot nano-object and the liquid medium. The predictions of this model will be systematically assessed by direct comparison with shadowgraphy experiments realized by the ILM2 team. These latter experiments will allow us to characterize both boiling threshold and the nanobubble dynamics with micronic spatial and nanosecond time resolutions. To tackle environmental effects, a specific chamber will be designed to cover a broad range of pressures and to investigate the influence of dissolved gas. An important input to the phase field code will come from electromagnetism simulations as performed by team at CETHIL. Comparison between the simulation predictions with and without near-field thermal radiation will highlight the role of this effect in the nanobubble dynamics.
The project is structured around four interrelated workpackages in addition to the management workpackage. In the first workpackage, the effects of the nanoparticle shape will be highlighted through a combination of shadowgraphy experiments and phase field simulations. The same techniques will be employed in the second workpackage, which aims at probing the influence of the pressure and the dissolved gas on boiling. The third workpackage will be devoted to the near-field thermal radiation modeling across the nanobubble. The last workpackage aims as establishing the fundamental laws of boiling at the nanoscales taking into account in particular environmental effects as well as near field radiation thermal transfer. The fundamental knowledge gained during this project may be exploited in the prevention of nuclear power plants accidents and in the optimization of microscale heat exchangers.

Project coordination

Samy MERABIA (INSTITUT LUMIERE MATIERE)

The author of this summary is the project coordinator, who is responsible for the content of this summary. The ANR declines any responsibility as for its contents.

Partner

ILM INSTITUT LUMIERE MATIERE
CETHIL CENTRE D' ÉNERGÉTIQUE ET DE THERMIQUE DE LYON
ILM INSTITUT LUMIERE MATIERE

Help of the ANR 404,880 euros
Beginning and duration of the scientific project: December 2021 - 48 Months

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