Ultrascalable Surface Structuring Strategy of Metal Additively Manufactured Materials for Enhanced Condensation

Abstract

Metal additive manufacturing (AM) enables unparalleled design freedom for the development of optimized devices in a plethora of applications. The requirement for the use of nonconventional aluminum alloys such as AlSi10Mg has made the rational micro/nanostructuring of metal AM challenging. Here, the techniques are developed and the fundamental mechanisms governing the micro/nanostructuring of AlSi10Mg, the most common metal AM material, are investigated. A surface structuring technique is rationally devised to form previously unexplored two-tier nanoscale architectures that enable remarkably low adhesion, excellent resilience to condensation flooding, and enhanced liquid-vapor phase transition. Using condensation as a demonstration framework, it is shown that the two-tier nanostructures achieve 6× higher heat transfer coefficient when compared to the best filmwise condensation. The study demonstrates that AM-enabled nanostructuring is optimal for confining droplets while reducing adhesion to facilitate droplet detachment. Extensive benchmarking with past reported data shows that the demonstrated heat transfer enhancement has not been achieved previously under high supersaturation conditions using conventional aluminum, further motivating the need for AM nanostructures. Finally, it has been demonstrated that the synergistic combination of wide AM design freedom and optimal AM nanostructuring method can provide an ultracompact condenser having excellent thermal performance and power density.

Advances in micro and nanoengineered surfaces for enhancing boiling and condensation heat transfer: a review

“…12D). Comparison of the jumping droplet condensation HTC of multi-tier cellular nanostructured surface (AM-EB) with previously reported superhydrophobic surfaces i.e., CuO nanostructures, 18 Cu hierarchical nanostructures, 219 Cu nanowire, 200 3D Cu nanowire, 195 Cu nanocone, 217 Cu nanograss, 199 Si nanowire, 202 Si micro/nanostructures, 220 and conventional Al nanostructures, 201 shows its signicantly improved performance at higher subcooling temperatures (Fig. 12E).…”

“…17A) were shown to enable a 33% to 45% improvement in ow condensation HTC of R410a when compared to smooth tubes. 201 For condensation heat transfer of R141b, implementation of copper oxide nanostructures was able to provide a 16.67% enhancement compared to the original copper channel with contact angle of 12.8°, which was attributed to the capillary force accelerating the condensate liquid when the mass ux was less than 400 kg (m 2 s) −1 . 273 For steam condensation applications, a tube with a metal foam internal surface (Fig.…”

“…Recent studies have focused on synergistic combination of micro and nanostructuring of AM metal surfaces along with its design exibility to further enhance condensation performance. 201,210,266 Due to signicantly different elemental composition of AM materials along with the AM laser melting and rapid solidication processes, as fabricated AM surfaces consist of unique sub-grain structures compared to conventionally manufactured metal surfaces. [267][268][269] Researchers have demonstrated that these unique sub-grains have unveiled the possibility of generating unique micro and nanostructures by varying heat and chemical treatment of AM surfaces.…”

Manipulation of droplets and bubbles for thermal applications

“…As such, scalable manufacturing methods such as chemical etching and oxidation 120 and sandblasting 121 have recently been developed to obtain required surface morphologies. Furthermore, an emerging area of interest is to utilize additive manufacturing to engineer micro‐ and macrostructures for thermal applications 122–125 …”

“…Furthermore, an emerging area of interest is to utilize additive manufacturing to engineer micro-and macrostructures for thermal applications. [122][123][124][125] While useful, static manipulation techniques lack real-time control and tunability which is often desired in practical applications.…”