Scalable and Resilient Etched Metallic Micro- and Nanostructured Surfaces for Enhanced Flow Boiling

Nithin Upot, Allison Mahvi, Kazi Rabbi, Jiaqi Li, Anthony Jacobi, Nenad Miljkovic

Research output: Contribution to journalArticlepeer-review

22 Scopus Citations

Abstract

Flow boiling and evaporation in tubes and channels occur in a wide variety of energy systems, such as refrigeration, air conditioning, power generation, electronics cooling, distillation, and purification. In this work, we demonstrate remarkably increased heat transfer coefficients of 270% during refrigerant flow boiling in scalable microstructured (~40 µm), industrial-scale (~1 m long) aluminum (Al) tubes, when compared to smooth unstructured Al tubes. To achieve scalable nanomanufacturing, we create highly conformal and durable structured surfaces by relying on hydrochloric acid Al etching. Flow boiling tests were conducted in 6.35 mm diameter Al tubes using R134a refrigerant as the working fluid. To benchmark our approach and to elucidate the effect of the structure length scale, we also fabricated ultrascalable boehmite (AlO(OH)) nanostructured (~300 nm) Al tubes, showing that etched microscale features are necessary and key to enhancement. Durability tests conducted using a 28 day long continual flow boiling experiment demonstrated negligible degradation of the etched surfaces. The scalable and cost-effective techniques used to create these durable, etched-Al microstructures may significantly reduce manufacturing cost when contrasted with current enhancement approaches such as extrusion, drawing, and welding.
Original languageAmerican English
Pages (from-to)6648-6658
Number of pages11
JournalACS Applied Nano Materials
Volume4
Issue number7
DOIs
StatePublished - 2021

NREL Publication Number

  • NREL/JA-5500-79233

Keywords

  • durable
  • enhancement
  • etching
  • flow boiling
  • heat transfer
  • microstructure
  • scalable

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