Evaporation at microscopic scale and at high heat flux

Abstract : This thesis theoretically investigates the transport processes in the vicinity of the triple gas-liquid-solid contact line and its impact on macroscopic evaporation. In the first part of the thesis, the hydrodynamics close to the contact line at partial wetting is studied. Specifically, evaporation into the atmosphere of pure vapor driven by heating of the substrate is considered. The question of singularity relaxation is addressed. The main finding of the thesis is that the Kelvin effect (dependence of saturation temperature on pressure) is sufficient by itself to relax the hydrodynamic contact line singularity. The proposed microregion (the contact line vicinity) model for small interface slopes is solved numerically. Asymptotic solutions are found for some specific cases. The governing length scales of the problem are identified and the multiscale nature of the phenomenon is addressed. Parametric studies revealing the role of the thermal resistance of vapor-liquid interface, slip length, thermocapillary term, the vapor recoil and surface forces are also performed. An extension of the lubrication approximation for high slopes of the gas-liquid interface at evaporation is discussed. In the second part of the thesis, the previously established microregion model is coupled to a simplified single vapor bubble growth numerical simulation. The bubble departure from the heater at boiling is also studied. It was proposed in the thesis, that under high heat loads, the increase of the apparent contact angle causes the vapor bubble to spread over the heated substrate. Such a behavior may cause the heater dry-out that occurs during the boiling crisis.
Complete list of metadatas

Cited literature [163 references]  Display  Hide  Download

https://pastel.archives-ouvertes.fr/tel-00782517
Contributor : Vladislav Janecek <>
Submitted on : Tuesday, January 29, 2013 - 11:27:16 PM
Last modification on : Tuesday, May 14, 2019 - 11:06:02 AM
Long-term archiving on : Saturday, April 1, 2017 - 12:36:17 PM

Identifiers

  • HAL Id : tel-00782517, version 1

Citation

Vladislav Janecek. Evaporation at microscopic scale and at high heat flux. Other [cond-mat.other]. Université Pierre et Marie Curie - Paris VI, 2012. English. ⟨tel-00782517⟩

Share

Metrics

Record views

1028

Files downloads

1175