Enhancement of critical heat flux using nano-fluids for Invessel Retention–External Vessel Cooling

This study investigated the pool boiling critical heat flux (CHF) of water-based nano-fluids under atmospheric pressure for Invessel Retention (IR)–External Vessel Cooling (EVC). The heated surface was a stainless steel foil inclined at different orientation angle from 0° (horizontal downward facing...

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Bibliographic Details
Published in:Applied thermal engineering 2012-03, Vol.35, p.157-165
Main Authors: Pham, Q.T., Kim, T.I., Lee, S.S., Chang, S.H.
Format: Article
Language:English
Subjects:
Applied sciences
Boiling
CHF
Contact angle
Cooling
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Heat flux
Heat transfer
IVR
Nano-fluids
Nanocomposites
Nanomaterials
Nanostructure
Orientation
Pool boiling
Roughness
Theoretical studies. Data and constants. Metering
Vessels
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Summary:This study investigated the pool boiling critical heat flux (CHF) of water-based nano-fluids under atmospheric pressure for Invessel Retention (IR)–External Vessel Cooling (EVC). The heated surface was a stainless steel foil inclined at different orientation angle from 0° (horizontal downward facing position) to 90° (vertical position). Three working nano-fluids with high suspension stability were selected by the zeta potential method to investigate the effect of each nano-fluid on CHF at the heated surface, which were 0.05% Alumine (Al2O3), 0.05% carbon nanotubes (CNT) + 10% boric acid and 0.05% Al2O3 + 0.05% CNT. It was observed that these nano-fluids enhanced CHF significantly (up to 220%) compared to deionized (DI) water. Furthermore, for all test fluids, CHF increased when the orientation angle increased. The surface characterization after boiling tests shows that the CHF enhancement with nano-fluids can be related to the increase of both surface roughness and wettability caused by nanoparticle deposition during the boiling processes. ▸ Selection of high suspension stability nano-fluids by zeta potential method (0.05% aluminum oxide (Al2O3); 0.05% carbon nanotubes (CNT) + 10% boric acid; and 0.05% Al2O3 + 0.05% CNT). ▸ Nano-fluids enhanced critical heat flux (CHF) significantly (up to 220%) compared to deionized (DI) water. ▸ CHF increased when the orientation angle increased. ▸ CHF enhancement with nano-fluids can be related to the increases of both surface roughness and wettability caused by nanoparticle deposition during the boiling processes.
ISSN:1359-4311
DOI:10.1016/j.applthermaleng.2011.10.017