Personal web page : http://iramis.cea.fr/Pisp/vadim.nikolayev/
Laboratory link : http://iramis.cea.fr/spec/SPHYNX/
More : http://iramis.cea.fr/Phocea/Vie_des_labos/Ast/ast_visu.php?id_ast=2271&id_unit=9&id_groupe=214
The thermal management of the components of vehicles or electronic devices is necessary to prevent overheating of the heat-emitters (like engines, processors, etc.) and to recover the heat to use elsewhere. Increasingly effective means of transfer of heat are required. The Pulsating Heat Pipe (PHP) is a promising solution well suitable for the transfer of high powers. The PHP is an extremely simple system. It is a closed capillary tube filled with a two-phase liquid able to transfer heat from its hot part (evaporator) to the cold part (condenser). Neither wick nor internal complex structure are required. The internal diameter of the tube needs to be small so that the alternating liquid plugs and vapor bubbles form inside it. The tube meanders between the evaporator and condenser thus forming multiple branches (i.e. parallel tubes). It turns out that the self-sustained oscillating motion of bubbles and plugs begin in this system when the temperature difference between the condenser and evaporator is applied. Such a convective motion and caused by it convective heat transfer make PHP extremely efficient with respect to other types of heat pipes. However, contrary to them, its functioning is non-stationary and thus more difficult to understand and model. The aim of the thesis is two-fold. First, we need to theoretically understand the hydrodynamic flow of a Taylor bubble in the presence of oscillations and phase change. Second, the collective behavior of all the bubbles inside PHP will be studied with the methods of non-linear dynamics and the computer code CASCO (French abbreviation meaning Advanced Code of PHP Simulation) developed at CEA. This is essential for mastering different oscillation regimes in order to convert CASCO into a design tool for industrial applications. The work will be conducted in collaboration with experimental groups within national and international research projects.