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Particle aspect-ratio and agglomeration-state effects on the effective thermal conductivity of aqueous suspensions of multiwalled carbon nanotubes / Anna S. Cherkasova in Journal of heat transfer, Vol. 132 N° 8 (Août 2010) 

Public ISBD [article]  in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp. [082402-1/11] Titre : Particle aspect-ratio and agglomeration-state effects on the effective thermal conductivity of aqueous suspensions of multiwalled carbon nanotubes Type de document : texte imprimé Auteurs : Anna S. Cherkasova, Auteur ; Jerry W. Shan, Auteur Article en page(s) : pp. [082402-1/11] Note générale : Physique Langues : Anglais (eng) Mots-clés : Nanofluid  Multiwalled  nonotubes  Thermal  conductivity  Aspect  ratio  Agglomeration  Interfacial  resistance  Effective  medium  theory Index. décimale : 536 Chaleur. Thermodynamique Résumé : The effective thermal conductivities of aqueous nanofluids containing surfactant-stabilized multiwalled carbon nanotubes were measured and compared with the predictions of effective medium theory (Nan, C.-W., et al., 1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys., 81(10), pp. 6692–6699). Detailed characterization of nanotube morphology was carried out through electron microscopy, while the nanotube agglomeration state was monitored through optical microscopy and absorption measurements. An optimum surfactant-to-nanotube mass ratio was found for the particular surfactant, sodium dodecylbenzene sulfonate, which resulted in the greatest increase in thermal conductivity. Taking into consideration the volume-weighted aspect ratio of the nanotubes, the measured thermal conductivities of the suspensions were shown to be in good agreement with calculations for a reasonable choice of interfacial resistance on the particle/liquid interface. The effect of particle aspect ratio on the suspension's thermal conductivity was further demonstrated and compared with theory by reducing the nanotube length through intense ultrasonication. The effect of particle aggregation on the thermal conductivity was also investigated by destabilizing previously stable suspensions with ethanol addition, which causes surfactant desorption and bundling of nanotubes. The measured thermal conductivities were correlated with absorption measurements and microscopic visualizations to show that particle aggregation decreases the thermal conductivity of the nanofluid by reducing the effective particle aspect ratio. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...] [article] Particle aspect-ratio and agglomeration-state effects on the effective thermal conductivity of aqueous suspensions of multiwalled carbon nanotubes [texte imprimé] / Anna S. Cherkasova, Auteur ; Jerry W. Shan, Auteur . - pp. [082402-1/11]. Physique Langues : Anglais (eng) in Journal of heat transfer > Vol. 132 N° 8 (Août 2010) . - pp. [082402-1/11] Mots-clés : Nanofluid  Multiwalled  nonotubes  Thermal  conductivity  Aspect  ratio  Agglomeration  Interfacial  resistance  Effective  medium  theory Index. décimale : 536 Chaleur. Thermodynamique Résumé : The effective thermal conductivities of aqueous nanofluids containing surfactant-stabilized multiwalled carbon nanotubes were measured and compared with the predictions of effective medium theory (Nan, C.-W., et al., 1997, “Effective Thermal Conductivity of Particulate Composites With Interfacial Thermal Resistance,” J. Appl. Phys., 81(10), pp. 6692–6699). Detailed characterization of nanotube morphology was carried out through electron microscopy, while the nanotube agglomeration state was monitored through optical microscopy and absorption measurements. An optimum surfactant-to-nanotube mass ratio was found for the particular surfactant, sodium dodecylbenzene sulfonate, which resulted in the greatest increase in thermal conductivity. Taking into consideration the volume-weighted aspect ratio of the nanotubes, the measured thermal conductivities of the suspensions were shown to be in good agreement with calculations for a reasonable choice of interfacial resistance on the particle/liquid interface. The effect of particle aspect ratio on the suspension's thermal conductivity was further demonstrated and compared with theory by reducing the nanotube length through intense ultrasonication. The effect of particle aggregation on the thermal conductivity was also investigated by destabilizing previously stable suspensions with ethanol addition, which causes surfactant desorption and bundling of nanotubes. The measured thermal conductivities were correlated with absorption measurements and microscopic visualizations to show that particle aggregation decreases the thermal conductivity of the nanofluid by reducing the effective particle aspect ratio. DEWEY : 536 ISSN : 0022-1481 En ligne : http://asmedl.aip.org/vsearch/servlet/VerityServlet?KEY=JHTRAO&ONLINE=YES&smode= [...]