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Technical Brief

Experimental Study on Convective Heat Transfer Performance of Iron Oxide Based Ferrofluids in Microtubes

[+] Author and Article Information
Evrim Kurtoğlu, Alihan Kaya

Mechatronics Engineering Program,
Sabancı University,
Tuzla, Istanbul 34956, Turkey

Devrim Gözüaçık

Biological Sciences and Bioengineering Program,
Sabancı University,
Tuzla, Istanbul 34956, Turkey

Havva Funda Yağcı Acar

Chemistry Department,
Koç University,
Sarıyer, Istanbul 34450, Turkey

Ali Koşar

Mechatronics Engineering Program,
Sabancı University,
Tuzla, Istanbul 34956, Turkey
e-mail: kosara@sabanciuniv.edu

1Corresponding author.

Contributed by the Heat Transfer Division of ASME for publication in the JOURNAL OF THERMAL SCIENCE AND ENGINEERING APPLICATIONS. Manuscript received January 17, 2013; final manuscript received January 7, 2014; published online March 17, 2014. Assoc. Editor: Arun Muley.

J. Thermal Sci. Eng. Appl 6(3), 034501 (Mar 17, 2014) (7 pages) Paper No: TSEA-13-1009; doi: 10.1115/1.4026490 History: Received January 17, 2013; Revised January 07, 2014

Ferrofluids are colloidal suspensions, in which the solid phase material is composed of magnetic nanoparticles, while the base fluid can potentially be any fluid. The solid particles are held in suspension by weak intermolecular forces and may be made of materials with different magnetic properties. Magnetite is one of the materials used for its natural ferromagnetic properties. Heat transfer performance of ferrofluids should be carefully analyzed and considered for their potential of their use in wide range of applications. In this study, convective heat transfer experiments were conducted in order to characterize convective heat transfer enhancements with lauric acid coated ironoxide (Fe3O4) nanoparticle based ferrofluids, which have volumetric fractions varying from 0% to ∼5% and average particle diameter of 25 nm, in a hypodermic stainless steel microtube with an inner diameter of 514 μm, an outer diameter of 819 μm, and a heated length of 2.5 cm. Heat fluxes up to 184 W/cm2 were applied to the system at three different flow rates (1 ml/s, 0.62 ml/s, and 0.36 ml/s). A decrease of around 100% in the maximum surface temperature (measured at the exit of the microtube) with the ferrofluid compared to the pure base fluid at significant heat fluxes (>100 W/cm2) was observed. Moreover, the enhancement in heat transfer increased with nanoparticle concentration, and there was no clue for saturation in heat transfer coefficient profiles with increasing volume fraction over the volume fraction range in this study (0–5%). The promising results obtained from the experiments suggest that the use of ferrofluids for heat transfer, drug delivery, and biological applications can be advantageous and a viable alternative as new generation coolants and futuristic drug carriers.

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Figures

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Fig. 1

(a) DLS result for aqueous solution of SPIONs. Nanoparticle size distribution just after preparation. (b) DLS result for aqueous solution of SPIONs. Nanoparticle size distribution 9 months after preparation. (c) Sample TEM images for pure nanofluid.

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Fig. 2

(a) Experimental setup and (b) detailed view of the heated section (TC: thermocouple)

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Fig. 3

Experimental Nusselt number data for pure water

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Fig. 4

Comparison between the experimental data and existing theory for pure water

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Fig. 5

Surface temperature rise (with respect to ambient temperature) at (a) Q = 0.36 ml/s, (b) Q = 0.62 ml/s, and (c) Q = 1 ml/s

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Fig. 6

Heat transfer coefficients as a function of applied heat flux at (a) Q = 0.36 ml/s, (b) Q = 0.62 ml/s, and (c) Q = 1 ml/s

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Fig. 7

Heat transfer coefficient enhancement (h/hpure water) at (a) Q = 0.36 ml/s, (b) Q = 0.62 ml/s, and (c) Q = 1 ml/s

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Fig. 8

Heat transfer enhancement (in %) as a function of dilution amount (with respect to the high concentration nanofluid)

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