Geometrically unrestricted vapour chambers enabled by additive manufacturing
Efficient cooling and heating solutions are a crucial part to improve efficiencies and reduce thermal losses. But complex shapes and tight volumetric constraints complicate efficient solutions or make it impossible to exchange the heat directly where it needs to be. Therefore heat transfer devices are used, such as heat pipes and vapour chambers. These function by phase transitions and convection of a working fluid inside a hermetically closed space. The multilayered shell-structure, consisting of a dense outer shell an intermediate porous layer and an empty core, is quit complicated to manufacture especially for complex shapes. In this case the freedom in design capability of additive manufacturing is utilised to eliminate the geometrical limitations. The additive manufacturing technology which is used in this case is Laser Powder Bed Fusion. To create a porous intermediate layer, the laser parameters need to be adjusted in a particular way to melt the powder particles just partially together. The core is needed for the convection of the evaporated working fluid from the evaporating regions to condensing regions. The least flow resistance would mean the core is completely empty but a coarse lattice structure is also admissible. Using a lattice inside the vapour chamber allows us to produce the vapour chambers in any shape because we do not infringe any overhang constraints from the additive manufacturing process. To further enhance the freedom in design of these heat transfer devices we developed an automated design algorithm that just needs the desired outside geometry as an input. An example where this could be beneficial is a tool for injection moulding where a fast and uniform cooling of the part is crucial for quality and profitability. Because of the exceptionally thermal conductivity nearly the whole insert has the same temperature and therefore provides a homogeneous solidification of part without warping.