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On the mechanism of pool boiling critical heat flux enhancement in nanofluids / Hyungdae Kim in Journal of heat transfer, Vol. 132 N° 6 (Juin 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 6 (Juin 2010) . - pp. [061501-1/11] Titre : On the mechanism of pool boiling critical heat flux enhancement in nanofluids Type de document : texte imprimé Auteurs : Hyungdae Kim, Auteur ; Ho Seon Ahn, Auteur ; Moo Hwan Kim, Auteur Article en page(s) : pp. [061501-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Critical  heat  flux  Evaporating  meniscus  Nanoparticle  deposition  Wetting Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pool boiling characteristics of water-based nanofluids with alumina and titania nanoparticles of 0.01 vol % were investigated on a thermally heated disk heater at saturated temperature and atmospheric pressure. The results confirmed the findings of previous studies that nanofluids can significantly enhance the critical heat flux (CHF), resulting in a large increase in the wall superheat. It was found that some nanoparticles deposit on the heater surface during nucleate boiling, and the surface modification due to the deposition results in the same magnitude of CHF enhancement in pure water as for nanofluids. Subsequent to the boiling experiments, the interfacial properties of the heater surfaces were examined using dynamic wetting of an evaporating water droplet. As the surface temperature increased, the evaporating meniscus on the clean surface suddenly receded toward the liquid due to the evaporation recoil force on the liquid-vapor interface, but the nanoparticle-fouled surface exhibited stable wetting of the liquid meniscus even at a remarkably higher wall superheat. The heat flux gain attainable due to the improved wetting of the evaporating meniscus on the fouled surface showed good agreement with the CHF enhancement during nanofluid boiling. It is supposed that the nanoparticle layer increases the stability of the evaporating microlayer underneath a bubble growing on a heated surface and thus the irreversible growth of a hot/dry spot is inhibited even at a high wall superheat, resulting in the CHF enhancement observed when boiling nanofluids. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] On the mechanism of pool boiling critical heat flux enhancement in nanofluids [texte imprimé] / Hyungdae Kim, Auteur ; Ho Seon Ahn, Auteur ; Moo Hwan Kim, Auteur . - pp. [061501-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 6 (Juin 2010) . - pp. [061501-1/11] Mots-clés : Critical  heat  flux  Evaporating  meniscus  Nanoparticle  deposition  Wetting Index. décimale : 536 Chaleur. Thermodynamique Résumé : The pool boiling characteristics of water-based nanofluids with alumina and titania nanoparticles of 0.01 vol % were investigated on a thermally heated disk heater at saturated temperature and atmospheric pressure. The results confirmed the findings of previous studies that nanofluids can significantly enhance the critical heat flux (CHF), resulting in a large increase in the wall superheat. It was found that some nanoparticles deposit on the heater surface during nucleate boiling, and the surface modification due to the deposition results in the same magnitude of CHF enhancement in pure water as for nanofluids. Subsequent to the boiling experiments, the interfacial properties of the heater surfaces were examined using dynamic wetting of an evaporating water droplet. As the surface temperature increased, the evaporating meniscus on the clean surface suddenly receded toward the liquid due to the evaporation recoil force on the liquid-vapor interface, but the nanoparticle-fouled surface exhibited stable wetting of the liquid meniscus even at a remarkably higher wall superheat. The heat flux gain attainable due to the improved wetting of the evaporating meniscus on the fouled surface showed good agreement with the CHF enhancement during nanofluid boiling. It is supposed that the nanoparticle layer increases the stability of the evaporating microlayer underneath a bubble growing on a heated surface and thus the irreversible growth of a hot/dry spot is inhibited even at a high wall superheat, resulting in the CHF enhancement observed when boiling nanofluids. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]