Abstract
The pool boiling critical heat flux (CHF) performance of aqueous nanofluids was investigated using various nanoparticles of TiO2, Al2O3, and SiO2. The usage of a nanofluid as a working fluid can significantly enhance the pool boiling CHF, which was found to be strongly dependent on the kind of nanoparticle, as well as its concentration. A nanoparticle surface coating was observed on the heating surface after the experiment. The CHF of pure water on the nanoparticle-coated surface was higher than that of nanofluids for all cases. This revealed that the cause of the CHF enhancement using nanofluids is due to the fact that the heater surface is modified by the nanoparticle deposition. The mechanism of CHF enhancement due to the nanoparticle coating was discussed, relating it to surface wettability, surface roughness, and maximum capillary wicking height of the nanoparticle-coated surface.
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Abbreviations
- D :
-
Wire diameter (m)
- hfg :
-
Latent heat of vaporization (J kg−1)
- I :
-
Current passing through wire heater (A)
- L :
-
Wire heater length (m)
- L c :
-
Capillary wicking height (m)
- \( {\ifmmode\expandafter\dot\else\expandafter\.\fi{q}}\ifmmode{''}\else$''$\fi_{{{\text{CHF}}}} \) :
-
Critical heat flux (W m−2)
- \( {\ifmmode\expandafter\dot\else\expandafter\.\fi{q}}\ifmmode{''}\else$''$\fi_{{{\text{CHF}},Z}} \) :
-
Critical heat flux predicted by Zuber (W m−2)
- Ra:
-
Surface roughness (m)
- V:
-
Voltage applied to wire heater (V)
- μ:
-
Viscosity (N s m−2)
- ρ:
-
Density (kg m−3)
- σ:
-
Surface tension (N m−1)
- ϕ:
-
Nanoparticle volume concentration (%)
- f:
-
Saturated liquid
- g:
-
Saturated vapor
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Acknowledgments
This research was supported by the National Research Laboratory project of the Korean Ministry of Science and Technology.
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Kim, H., Kim, M. Experimental study of the characteristics and mechanism of pool boiling CHF enhancement using nanofluids. Heat Mass Transfer 45, 991–998 (2009). https://doi.org/10.1007/s00231-007-0318-8
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DOI: https://doi.org/10.1007/s00231-007-0318-8