Superwetting Surface for Diminishing Leidenfrost Effect

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Superwetting Surface for Diminishing Leidenfrost Effect
Categories
Inventors
Professor Kripa Varanasi
Department of Mechanical Engineering, MIT
External Link (varanasi.mit.edu)
Christopher Love
Department of Mechanical Engineering, MIT
Adam Paxson
Department of Mechanical Engineering, MIT
Hyukmin Kwon
Department of Mechanical Engineering, MIT
Jonathan Smith
Department of Mechanical Engineering, MIT
Managed By
Christopher Noble
MIT Technology Licensing Officer - Clean and Renewable Energy
Patent Protection

Superwetting surfaces for diminishing leidenfrost effect, methods of making and devices incorporating the same

US Patent 8,983,019
Publications
Increasing Leidenfrost Point Using Micro-nano Hierarchical Surface Structures
Applied Physics Letters, 103, 201601 (2013)

Applications

Superwetting surfaces can increase heat transfer and efficiency in two-phase cooling devices (heat exchangers).

Problem Addressed

Heat exchangers use boiling to transfer heat away from a solid. However, boiling is limited by the critical heat flux (CHF), which occurs at the Leidenfrost point, where a vapor is generated between the droplet and solid surface. The vapor causes heat transfer via conduction, which leads to dry-out and slows down heat transfer. A superwetting surface reduces the effects of the Leidenfrost effect by preventing vapor formation and continuously rewetting the surface; therefore, improving overall heat transfer.

Technology

Surface roughness can be used to create a superwetting surface that can fundamentally alter droplet-surface interactions to continuously rewet the surface and prevent vapor film formation. Micro scale square posts are fabricated on silicon wafers with photolithography followed by a reactive ion etch. Silica particles with different diameters, 15-75nm, are spin-coated and sintered on the substrates already having micro scale square posts to create a hierarchical structure. The textured surfaces significantly enhance nucleate boiling and diminish the Leidenfrost limits, which increases heat transfer and reduces dryout.

Advantages

  • Increases critical heat flux
  • Increases boiling efficiency