Development of Additive Manufactured Metal Wick Structures for Two-Phase Heat Transfer Applications

Additive manufacturing (AM) technologies offer the design freedom to create complex metal customizable structures with a remarkable increase in the area-to-volume ratios at minimal time and cost. This is enabling a new generation of two-phase exchangers, thermosyphons, and heat pipes. Wick design has been identified as the main parameter impacting the thermal performance of heat pipes and vapor chambers. Conventionally, these wicks are constructed by sintering metal powder or welding wire meshes to the inner wall of a heat pipe. The current work investigates using Laser Powder Bed Fusion (L-PBF) to build AM micro-structured wicks that are not amenable to fabricate using conventional methods. Four porous configurations are manufactured using the L-PBF: (i) body-centered cube (BCC), (ii) face-centered cube (FCC), (iii) simple cube (SC), and (iv) Voronoi. The porosity of each configuration was varied by changing the strut thickness from 0.25 mm to 0.35 mm. The capillary performance of these wicks was examined via the rate-of-rise experiment, in which the sample is dipped vertically in ethanol well, and the rate of the wicked mass is recorded using an accurate lab scale. The results showed that the SC configuration achieved the best hydraulic performance, with K/r eff up to 0.53 µm. Also, the rate-of-rise was higher when decreasing the unit cell size except for the Voronoi and the FCC. The current investigation is considered an important step toward the fabrication of high-performance one-piece AM two-phase heat sinks.