Enhancement of condensation heat transfer by hydrophobic and nano porous surface

Taeseok Kim, Yun Sik Cho, Sung Joong Kim, Jaemin Lee, Wonjoon Choi

Research output: Contribution to conferencePaper

Abstract

It has been well known that surface characteristics such as wettability, morphology, roughness influence on condensation heat transfer on the surface. Especially, hydrophobic and nano porous surfaces enhance condensation heat transfer performance to promote dropwise condensation. Few studies, however, have examined the effects of combined surface with hydrophobic and nano porous to the condensation heat transfer. In order to determine the combined surface effect, condensation heat transfer experiment using hydrophobic and nano porous surfaced was conducted. The nano porous surface was made using Layer-by-Layer (LbL) technique which uses electrically charged particle solutions. Whereas in the case of hydrophobic surface, Self-assembled monolayer (SAM) has been a good approach to control the surface wettability. The surface structure is left unchanged in the deposition of SAM because the particle size is almost small (~3nm), so it is great to make combined surface; nano porous and hydrophobic. In this study, the LbL assembled carbon nanotube (CNT) layers were fabricated to make nano porous surface. On the other hand, the hydrophobic coating is used as octadecyltrichlorosilane (OTS) which has hydrophobic functional group (-CH3). The condensation heat transfer experiment was carried out with four surfaces; bare, CNT, OTS, CNT+OTS. The experimental results indicated that the OTS surface has highest condensation heat transfer coefficient, and CNT+OTS, CNT in order and the bare is lowest. The hydrophobic surface enhances condensation heat transfer by promoting dropwise condensation, but these effects are decreased if it uses with nano porous surface

Original languageEnglish
Pages2447-2460
Number of pages14
StatePublished - 2019 Jan 1
Event18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019 - Portland, United States
Duration: 2019 Aug 182019 Aug 23

Conference

Conference18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019
CountryUnited States
CityPortland
Period19/08/1819/08/23

Keywords

  • Condensation heat transfer
  • Nano porous
  • Surface modification
  • Vertical tube
  • Wettability

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  • Cite this

    Kim, T., Cho, Y. S., Kim, S. J., Lee, J., & Choi, W. (2019). Enhancement of condensation heat transfer by hydrophobic and nano porous surface. 2447-2460. Paper presented at 18th International Topical Meeting on Nuclear Reactor Thermal Hydraulics, NURETH 2019, Portland, United States.