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Nitrogen-doped carbon nanotubes for heat transfer applications: Enhancement of conduction and convection properties of water/N-CNT nanofluid

Bazmi, M ; Sharif University of Technology | 2019

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  1. Type of Document: Article
  2. DOI: 10.1007/s10973-019-08024-y
  3. Publisher: Springer Netherlands , 2019
  4. Abstract:
  5. In this research, it is aimed to enhance the heat transfer properties of the carbon nanotubes through nitrogen doping. To this end, nitrogen-doped multiwall carbon nanotubes (N-CNTs) were synthesized via chemical vapor deposition method. For supplying carbon and nitrogen during the synthesis of N-CNTs, camphor and urea were used, respectively, at 1000 °C over Co–Mo/MgO nanocatalyst in a hydrogen atmosphere. N-CNTs with three different nitrogen loadings of 0.56, 0.98, and 1.38 mass% were synthesized, after which, water/N-CNT nanofluids of these three samples with concentrations of 0.1, 0.2, and 0.5 mass% were prepared. To obtain a stable nanofluid, N-CNTs were functionalized by nitric acid followed by stabilizing in water by employing the ultrasonic bath. Investigation on the stability of the samples showed a high stability level for the prepared water/N-CNT nanofluids in which the zeta potential of − 43.5 mV was obtained for the best sample. Also for studying the heat transfer properties, the thermal conductivity in the range of 0.1–0.5 mass% and convection heat transfer coefficients of nanofluids in the range of 0.1–0.5 mass%, and Reynolds number in the range of 4000–9000 were evaluated. The results showed 32.7% enhancement of the convection heat transfer coefficients at Reynolds number of 8676 and 27% increase in the thermal conductivity at 0.5 mass% and 30 °C. © 2019, Akadémiai Kiadó, Budapest, Hungary
  6. Keywords:
  7. Heat transfer ; Nanofluid ; Nitrogen-doped carbon nanotubes ; Rheological properties ; Chemical vapor deposition ; Doping (additives) ; Heat conduction ; Heat convection ; Heat transfer coefficients ; Multiwalled carbon nanotubes (MWCN) ; Nanocatalysts ; Nanotubes ; Nitrogen ; Reynolds number ; Thermal conductivity ; Thermal conductivity of liquids ; Ultrasonic testing ; Urea ; Yarn ; Chemical vapor deposition methods ; Conduction and convections ; Heat transfer applications ; Heat transfer properties ; Hydrogen atmosphere ; Nanofluids ; Nitrogen doped carbon nanotubes ; Rheological property ; Nanofluidics
  8. Source: Journal of Thermal Analysis and Calorimetry ; Volume 138, Issue 1 , 2019 , Pages 69-79 ; 13886150 (ISSN)
  9. URL: https://link.springer.com/article/10.1007/s10973-019-08024-y