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Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes (nanofluids)

Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes (nanofluids)
Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes (nanofluids)
Titanate nanotubes of an aspect ratio of ~10 are synthesized, characterised and dispersed in water to form stable nanofluids containing 0.5, 1.0 and 2.5 wt.% of the nanotubes. Experiments are then carried out to investigate the effective thermal conductivity, rheological behaviour and forced convective heat transfer of the nanofluids. The results show a small thermal conductivity enhancement of ~3% at 25 °C and ~5% at 40 °C for the 2.5 wt.% nanofluid. The nanofluids are found to be non-Newtonian with obvious shear thinning behaviour with the shear viscosity decreasing with increasing shear rate at low shear rates. The shear viscosity approaches constant at a shear rate higher than ~100–1000 s?1 depending nanoparticle concentration. The high shear viscosity is found to be much higher than that predicted by the conventional viscosity models for dilute suspensions. Despite the small thermal conduction enhancement, an excellent enhancement is observed on the convective heat transfer coefficient, which is much higher than that of the thermal conductivity enhancement. In comparison with nanofluids containing spherical titania nanoparticles under similar conditions, the enhancement of both thermal conductivity and convective heat transfer coefficient of the titanate nanotube nanofluids is considerably higher indicating the important role of particle shape in the heat transfer enhancement. Possible mechanisms are also proposed for the observed enhancement of the convective heat transfer coefficient.
0032-5910
63-72
Chen, Haisheng
e0df3365-2195-4db8-9b6d-c67091d25aaf
Yang, Wei
bc603ec9-d646-46ae-ab12-a1aed3aea245
He, Yurong
f8c05c06-b438-4ae0-9dd1-86f67ee6395d
Ding, Yulong
c7a631db-2c0e-4db4-aa38-03de3706952c
Zhang, Lingling
ae17b729-620d-4480-a072-85ca978a39e8
Tan, Chunqing
e06c28d0-c97b-4167-a052-8e7040b504f1
Lapkin, Alexei A.
e5550045-9bdc-4cca-873a-16c2f37a64c8
Bavykin, Dmitry V.
1e9fabfc-d078-4585-876f-85ff33b7eed5
Chen, Haisheng
e0df3365-2195-4db8-9b6d-c67091d25aaf
Yang, Wei
bc603ec9-d646-46ae-ab12-a1aed3aea245
He, Yurong
f8c05c06-b438-4ae0-9dd1-86f67ee6395d
Ding, Yulong
c7a631db-2c0e-4db4-aa38-03de3706952c
Zhang, Lingling
ae17b729-620d-4480-a072-85ca978a39e8
Tan, Chunqing
e06c28d0-c97b-4167-a052-8e7040b504f1
Lapkin, Alexei A.
e5550045-9bdc-4cca-873a-16c2f37a64c8
Bavykin, Dmitry V.
1e9fabfc-d078-4585-876f-85ff33b7eed5

Chen, Haisheng, Yang, Wei, He, Yurong, Ding, Yulong, Zhang, Lingling, Tan, Chunqing, Lapkin, Alexei A. and Bavykin, Dmitry V. (2008) Heat transfer and flow behaviour of aqueous suspensions of titanate nanotubes (nanofluids). Powder Technology, 183 (1), 63-72. (doi:10.1016/j.powtec.2007.11.014).

Record type: Article

Abstract

Titanate nanotubes of an aspect ratio of ~10 are synthesized, characterised and dispersed in water to form stable nanofluids containing 0.5, 1.0 and 2.5 wt.% of the nanotubes. Experiments are then carried out to investigate the effective thermal conductivity, rheological behaviour and forced convective heat transfer of the nanofluids. The results show a small thermal conductivity enhancement of ~3% at 25 °C and ~5% at 40 °C for the 2.5 wt.% nanofluid. The nanofluids are found to be non-Newtonian with obvious shear thinning behaviour with the shear viscosity decreasing with increasing shear rate at low shear rates. The shear viscosity approaches constant at a shear rate higher than ~100–1000 s?1 depending nanoparticle concentration. The high shear viscosity is found to be much higher than that predicted by the conventional viscosity models for dilute suspensions. Despite the small thermal conduction enhancement, an excellent enhancement is observed on the convective heat transfer coefficient, which is much higher than that of the thermal conductivity enhancement. In comparison with nanofluids containing spherical titania nanoparticles under similar conditions, the enhancement of both thermal conductivity and convective heat transfer coefficient of the titanate nanotube nanofluids is considerably higher indicating the important role of particle shape in the heat transfer enhancement. Possible mechanisms are also proposed for the observed enhancement of the convective heat transfer coefficient.

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More information

Published date: 18 March 2008
Additional Information: Selected papers from the UK-China Particle Technology Forum; Leeds UK, 1-3 April 2007
Organisations: Engineering Mats & Surface Engineerg Gp

Identifiers

Local EPrints ID: 50993
URI: https://eprints.soton.ac.uk/id/eprint/50993
ISSN: 0032-5910
PURE UUID: ea9d7bf1-f98f-4b15-94a1-e8d778b25b94

Catalogue record

Date deposited: 14 May 2008
Last modified: 13 Mar 2019 20:49

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