AARDECO

The increase of power density is one of the main challenges from both industrial and societal points of view in all industrial applications. This trend lasts for decades in the aeronautic industry because of weight reduction objective. The automotive industry currently undergoes a profound mutation from energetic point of view. Indeed, the miniaturization of the vehicle and its components and the progressive electrification lead together to an increase of the energy fluxes which requires. The management of the corresponding heat fluxes, i.e. their evacuation (cooling) or redirection is a key of this transformation both in energetic and financial aspects. In this way, the Pulsating Heat Pipe (PHP), invented in the 90s, is a promising solution for controlling of extremely high heat fluxes (>200 W/cm2). Indeed, the PHP is a relatively simple structure: a capillary tube of circular section bent into many turns and partially filled with a two-phase fluid that form inside a sequence of liquid plug separated by vapor bubbles. One bend of each loop is in thermal contact with the hot source and the other with the cold one. In addition, the PHP is generally is more efficient than the other type of heat pipes: the liquid plugs movement from cold to hot source generate not only the latent heat exchange by phase transition (evaporation/condensation) but also a convective heat transfer. However, contrary to other types of heat pipes, is functioning is non-stationary, thus more difficult to understand and to model. Today, there is no tool to design a PHP. Numerous scientific problems are still to overcome: wall film effects on the dynamic behavior of the vapor bubbles (viscous friction), on the liquid pugs, on the heat transfer, the yet unknown vapor thermodynamic state, etc. For this purpose a part of the project tasks will focus on the understanding of the PHP’s elementary mechanisms, with minimal system complexity (single-bubble PHP). Within the project, these findings will help to improve the existing numerical code that will be used next to design the multi-bubble PHP for application in both automotive and aeronautic industries. These multi-bubbles PHP will be developed for validation of the code and also to obtain complementary information on transient behavior of the PHP and impact of perturbations (vibration). The project will be carried out by three academic laboratories whose expertise on the PHP is well established (CEA/SBT, CETHIL and Institute P’) and two industrial partners belonging to different industrial domains (Liebherr Aerospace Toulouse and PSA).