Premium
Pool boiling on a superhydrophilic surface
Author(s) -
Takata Y.,
Hidaka S.,
Masuda M.,
Ito T.
Publication year - 2003
Publication title -
international journal of energy research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.808
H-Index - 95
eISSN - 1099-114X
pISSN - 0363-907X
DOI - 10.1002/er.861
Subject(s) - superhydrophilicity , wetting , boiling , contact angle , materials science , heat transfer , heat flux , nucleate boiling , critical heat flux , composite material , chemical engineering , chemistry , thermodynamics , physics , organic chemistry , engineering
Titanium Dioxide, TiO 2 , is a photocatalyst with a unique characteristic. A surface coated with TiO 2 exhibits an extremely high affinity for water when exposed to UV light and the contact angle decreases nearly to zero. Inversely, the contact angle increases when the surface is shielded from UV. This superhydrophilic nature gives a self‐cleaning effect to the coated surface and has already been applied to some construction materials, car coatings and so on. We applied this property to the enhancement of boiling heat transfer. An experiment involving the pool boiling of pure water has been performed to make clear the effect of high wettability on heat transfer characteristics. The heat transfer surface is a vertical copper cylinder of 17 mm in diameter and the measurement has been done at saturated temperature and in a steady state. Both TiO 2 ‐coated and non‐coated surfaces were used for comparison. In the case of the TiO 2 ‐coated surface, it is exposed to UV light for a few hours before experiment and it is found that the maximum heat flux (CHF) is about two times larger than that of the uncoated surface. The temperature at minimum heat flux (MHF) for the superhydrophilic surface is higher by 100 K than that for the normal one. The superhydrophilic surface can be an ideal heat transfer surface. Copyright © 2002 John Wiley & Sons, Ltd.