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Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?

Chiavazzo E, Asinari P - Nanoscale Res Lett (2011)

Bottom Line: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties.As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes.Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 W·m-2·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surfaces.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Energetics, Politecnico di Torino, Corso Duca degli Abruzzi, 10129 Torino, Italy. pietro.asinari@polito.it.

ABSTRACT

Background: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties. Nevertheless, it was proven that, due to modest dispersion of nanoparticles, such high expectations often remain unmet. In this article, by introducing the notion of nanofin, a possible solution is envisioned, where nanostructures with high aspect-ratio are sparsely attached to a solid surface (to avoid a significant disturbance on the fluid dynamic structures), and act as efficient thermal bridges within the boundary layer. As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes.

Results: Toward the end of implementing the above idea, we focus on single carbon nanotubes to enhance heat transfer between a surface and a fluid in contact with it. First, we investigate the thermal conductivity of the latter nanostructures by means of classical non-equilibrium molecular dynamics simulations. Next, thermal conductance at the interface between a single wall carbon nanotube (nanofin) and water molecules is assessed by means of both steady-state and transient numerical experiments.

Conclusions: Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 W·m-2·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surfaces.

No MeSH data available.


Related in: MedlinePlus

Color online. A (5, 5) SWNT (green) is surrounded by water molecules (blue, red). Nosé-Hoover thermostats with temperature Thot = 360 K are coupled to the nanotube tips, while water is kept at a fixed temperature Tw = 300 K. After a sufficiently long time (here 15 ns), a steady-state condition is reached. MD simulation results (in terms of both temperature profile and heat flux) are consistent with a continuous one-dimensional model as described by Equations (17) and (18). Image obtained using VEGA ZZ [47].
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Figure 6: Color online. A (5, 5) SWNT (green) is surrounded by water molecules (blue, red). Nosé-Hoover thermostats with temperature Thot = 360 K are coupled to the nanotube tips, while water is kept at a fixed temperature Tw = 300 K. After a sufficiently long time (here 15 ns), a steady-state condition is reached. MD simulation results (in terms of both temperature profile and heat flux) are consistent with a continuous one-dimensional model as described by Equations (17) and (18). Image obtained using VEGA ZZ [47].

Mentions: In this section, we investigate on the heat transfer between a carbon nanotube and a surrounding fluid (water). The latter represents a first step toward a detailed study of a batch of single CNTs (or small bundles) utilized as carbon nanofins to enhance the heat transfer of a surface when transversally attached to it. To this end, and limited by the power of our current computational facilities, we consider a (5, 5) SWNT (with a length L ≤ 14 nm) placed in a box filled with water (typical setup is shown in Figure 6). SWNT end temperatures are set at a fixed temperature Thot = 360 K, while the solvent is kept at Tw = 300 K. The carbon-water interaction is taken into account by means of a Lennard-Jones potential between the carbon and oxygen atoms with a parameterization (ϵCO, σCO) reported in Table 1. Moreover, non-bonded interactions between the water molecules consist of both a Lennard-Jones term between oxygen atoms (with ϵOO, σOO from Table 1) and a Coulomb potential:(13)


Enhancing surface heat transfer by carbon nanofins: towards an alternative to nanofluids?

Chiavazzo E, Asinari P - Nanoscale Res Lett (2011)

Color online. A (5, 5) SWNT (green) is surrounded by water molecules (blue, red). Nosé-Hoover thermostats with temperature Thot = 360 K are coupled to the nanotube tips, while water is kept at a fixed temperature Tw = 300 K. After a sufficiently long time (here 15 ns), a steady-state condition is reached. MD simulation results (in terms of both temperature profile and heat flux) are consistent with a continuous one-dimensional model as described by Equations (17) and (18). Image obtained using VEGA ZZ [47].
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211310&req=5

Figure 6: Color online. A (5, 5) SWNT (green) is surrounded by water molecules (blue, red). Nosé-Hoover thermostats with temperature Thot = 360 K are coupled to the nanotube tips, while water is kept at a fixed temperature Tw = 300 K. After a sufficiently long time (here 15 ns), a steady-state condition is reached. MD simulation results (in terms of both temperature profile and heat flux) are consistent with a continuous one-dimensional model as described by Equations (17) and (18). Image obtained using VEGA ZZ [47].
Mentions: In this section, we investigate on the heat transfer between a carbon nanotube and a surrounding fluid (water). The latter represents a first step toward a detailed study of a batch of single CNTs (or small bundles) utilized as carbon nanofins to enhance the heat transfer of a surface when transversally attached to it. To this end, and limited by the power of our current computational facilities, we consider a (5, 5) SWNT (with a length L ≤ 14 nm) placed in a box filled with water (typical setup is shown in Figure 6). SWNT end temperatures are set at a fixed temperature Thot = 360 K, while the solvent is kept at Tw = 300 K. The carbon-water interaction is taken into account by means of a Lennard-Jones potential between the carbon and oxygen atoms with a parameterization (ϵCO, σCO) reported in Table 1. Moreover, non-bonded interactions between the water molecules consist of both a Lennard-Jones term between oxygen atoms (with ϵOO, σOO from Table 1) and a Coulomb potential:(13)

Bottom Line: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties.As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes.Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 W·m-2·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surfaces.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Energetics, Politecnico di Torino, Corso Duca degli Abruzzi, 10129 Torino, Italy. pietro.asinari@polito.it.

ABSTRACT

Background: Nanofluids are suspensions of nanoparticles and fibers which have recently attracted much attention because of their superior thermal properties. Nevertheless, it was proven that, due to modest dispersion of nanoparticles, such high expectations often remain unmet. In this article, by introducing the notion of nanofin, a possible solution is envisioned, where nanostructures with high aspect-ratio are sparsely attached to a solid surface (to avoid a significant disturbance on the fluid dynamic structures), and act as efficient thermal bridges within the boundary layer. As a result, particles are only needed in a small region of the fluid, while dispersion can be controlled in advance through design and manufacturing processes.

Results: Toward the end of implementing the above idea, we focus on single carbon nanotubes to enhance heat transfer between a surface and a fluid in contact with it. First, we investigate the thermal conductivity of the latter nanostructures by means of classical non-equilibrium molecular dynamics simulations. Next, thermal conductance at the interface between a single wall carbon nanotube (nanofin) and water molecules is assessed by means of both steady-state and transient numerical experiments.

Conclusions: Numerical evidences suggest a pretty favorable thermal boundary conductance (order of 107 W·m-2·K-1) which makes carbon nanotubes potential candidates for constructing nanofinned surfaces.

No MeSH data available.


Related in: MedlinePlus