Boiling and critical heat flux on surfaces of modified wettability and roughness

Joseph L. Bottini, Sabrina Hammouti, David Ruzic, Caleb S. Brooks

Research output: Contribution to conferencePaperpeer-review

Abstract

Boiling heat transfer is an effective method for transferring heat from system components, enabling high heat transfer rates from minimal surface superheats. While it is effective, two-phase heat transfer offers added complexities to single-phase heat transfer caused by the addition of deformable interfaces, dissimilar fluid properties, and phase transition. The critical heat flux (CHF) marks the upper limit of safe operation for many boiling heat transfer systems, and its prediction is essential to ensure safe operation. While much effort has been devoted to studying boiling heat transfer and CHF, the characteristics of the surface, such as wettability and roughness, influence the boiling heat transfer, but are not well understood. Heat transfer surfaces of varying wettability and roughness have been prepared, characterized, and subjected to flow experiments up to CHF to study the role the surface properties have in flow boiling heat transfer. The surfaces were prepared using a high-power laser to texture the surface altering the wettability and roughness. Increasing the roughness and decreasing the wettability are found to have competing effects on both the boiling curves and the CHF points. The onset of nucleate boiling (ONB) points are delayed for the less-wetting surfaces, and the CHF value is lower. An increase in roughness for the textured surface causes earlier ONB and increases CHF, but the CHF values are lower than for the original, polished surface. The roughness and wettability are demonstrated to be influential properties on both the boiling heat transfer and the CHF point, and are not well captured by the existing CHF models.

Original languageEnglish (US)
Pages440-448
Number of pages9
StatePublished - Jan 1 2018
EventInternational Topical Meeting on Advances in Thermal Hydraulics 2018, ATH 2018 - Held in conjunction with the 2018 American Nuclear Society (ANS) Winter Meeting - Orlando, United States
Duration: Nov 11 2018Nov 15 2018

Other

OtherInternational Topical Meeting on Advances in Thermal Hydraulics 2018, ATH 2018 - Held in conjunction with the 2018 American Nuclear Society (ANS) Winter Meeting
CountryUnited States
CityOrlando
Period11/11/1811/15/18

Keywords

  • Contact angle
  • Critical heat flux
  • Flow boiling
  • Roughness
  • Wettability

ASJC Scopus subject areas

  • Geotechnical Engineering and Engineering Geology
  • Nuclear Energy and Engineering
  • Nuclear and High Energy Physics

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