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Title
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Size effect on thermal conductivity and stability of TiO 2/MWCNT-based hybrid nanofluids synthesized via probe ultrasonication
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Type
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JournalPaper
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Keywords
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Hybrid nanofluids, Thermal conductivity, Carbon nanotubes, Ultrasonication, Thermal management.
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Abstract
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This study reports the enhancement of thermal conductivity in hybrid TiO2 grafted onto multi-wall carbon nanotubes (MWCNTs) dispersed in an ethylene glycol nanofluid synthesized by a scalable probeultrasonication process. The hybrid nanofluids were formulated at ultra-low loadings; MWCNT = 0.001 wt% (fixed) and TiO2 = 0.001–0.01 wt% (15 nm and 30 nm). The 15 nm TiO2 sample at 0.01 wt% achieved 16.7% thermal conductivity enhancement at 70 °C while maintaining >4 weeks stability. To the best of our knowledge, this is the first report achieving double-digit conductivity improvement at #0.01 wt% solids using a surfactant-free, scalable probe-ultrasonication route. Homogeneous and stable TiO2/MWCNT nanofluids were produced using a surfactant-free approach, and their performance was validated through Raman spectroscopy, Zetasizer, TEM, and UV-Vis analyses. Formulations with ultra-low loadings, MWCNT = 0.001 wt% (fixed) and TiO2 = 0.001–0.01 wt% (15 or 30 nm), were investigated. The sample containing 15 nm TiO2 at 0.01 wt% exhibited a reproducible 16.7% thermal-conductivity enhancement at 70 °C and maintained colloidal stability for over four weeks. Such a high enhancement at extremely low solid content in an ethylene glycol matrix, achieved through a surfactant-free and scalable ultrasonication route, has not been previously reported.
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Researchers
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Malek Maaza (Not In First Six Researchers), Ahmad Hussein (Not In First Six Researchers), Shohreh Azizi (Fifth Researcher), Itani Madiba (Fourth Researcher), Shiva Shafiei (Third Researcher), Meisam Aligholami (Second Researcher), Sara Heshmatian (First Researcher)
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