Manufacturing and thermohydraulic characterization of sintered capillary structure

International audienceIn many industrial applications, thermal issues affect electronic components. Indeed, they are smaller and smaller and dissipate higher heat fluxes. To solve these issues, heat pipes are very competitive and loop heat pipes (LHP) are among the most efficient systems as they enable to transfer the heat on long distances. The most important component of LHPs is certainly the evaporator. Indeed, the evaporator provides the force enabling the fluid to circulate in the entire system. Moreover, the characteristics of this component have a large influence on the evaporation of the working fluid and thus, on the thermal performance of the LHP. This work focuses on the fabrication and on the characterization of wicks specifically designed for LHPs. A model has shown that a double layer provides the best thermal and hydrodynamic performances. In the case of a flat evaporator, the bottom layer, in contact with the electronic component, necessitates a high thermal conductivity and the top layer, close to the reservoir, has to present a low thermal conductivity. The optimal wick characteristics being determined, several bottom layers are manufactured by partial sintering of a copper powder. A 2-level fractional factorial design is used in order to study the influence of the sintering parameters. These samples are characterized by means of two test benches designed in this purpose. They enable the determination of the permeability and of the effective pore radius. The main perspective of this this work is the improvement of the top layer. It is manufactured using freeze casting of ceria-stabilized zirconia powder. The preliminary results shows a high permeability and a pore radius being in the targeted range. A mechanical continuity must be obtained between the two layers in order to improve the global performance of a complete LHP