Nitrogen-doped carbon nanotubes for heat transfer applications

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-CN...

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Bibliographic Details
Published in:Journal of thermal analysis and calorimetry 2019-10, Vol.138 (1), p.69-79
Main Authors: Bazmi, Mohammad, Askari, Saeed, Ghasemy, Ebrahim, Rashidi, Alimorad, Ettefaghi, Ehsanollah
Format: Article
Language:English
Subjects:
Camphor
Carbon
Chemical synthesis
Chemical vapor deposition
Electric properties
Fluid flow
Heat conductivity
Heat transfer
Heat transfer coefficients
Multi wall carbon nanotubes
Nanofluids
Nanotubes
Nitric acid
Nitrogen
Organic chemistry
Reynolds number
Stability
Thermal conductivity
Urea
Zeta potential
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Summary: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.
ISSN:1388-6150
1588-2926
DOI:10.1007/s10973-019-08024-y