Transcript Nanofluids TC Errors

Effective Thermal Conductivity Errors
by Assuming Unidirectional Temperature
and Heat Flux Distribution
Within Heterogeneous Mixtures (Nanofluids)
The 5th WSEAS International Conference on HEAT and MASS TRANSFER
(WSEAS - HMT'08)
Acapulco, Mexico, January 25-27, 2009
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
© M. Kostic <www.kostic.niu.edu>
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Nanofluids Research:
Critical Issues & Application Potentials
Advanced Flow and Heat Transfer Fluids
Resistively Heated
Crucible
Liquid
Cooling System
Deionized water prior to Oil prior to (left) and
Presented at: University of Hawaii at Manoa
after (right)and
evaporation
(left) and after (right)
of Cu
nanoparticles
Multifunctional Nanocomposite
Int.
Conference
dispersion of Al2006
2O3
nanoparticles
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
© M. Kostic <www.kostic.niu.edu>
080125
First NIU Nanofluids
© M. Kostic <www.kostic.niu.edu>
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Wet-Nanotechnology:
nanofluids’ applications
Advanced, hybrid nanofluids:
Heat-transfer nanofluids (ANL & NIU)
Tribological nanofluids (NIU)
Surfactant and Coating nanofluids
Chemical nanofluids
Process/Extraction nanofluids
Environmental (pollution cleaning) nanofluids
Bio- and Pharmaceutical-nanofluids
Medical nanofluids
(drug delivery and functional tissue-cell interaction)
© M. Kostic <www.kostic.niu.edu>
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Production of Copper
Nanofluids
Nanofluids with copper
nanoparticles have been produced
by a one-step method.
Copper is evaporated and
condensed into nanoparticles by
direct contact with a flowing and
cooled (low-vapor-pressure) fluid.
Resistively Heated
Crucible
Liquid
ANL produced for the first time
stable suspensions of copper
nanoparticles in fluids w/o
dispersants.
Cooling System
Schematic diagram of nanofluid
production system designed for
direct evaporation/condensation of
metallic vapor into low-vaporpressure liquids.
© M. Kostic <www.kostic.niu.edu>
For some nanofluids, a small
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amount of thioglycolic acid
(<1 vol.%) was added to stabilize
nanoparticle suspension and further
improve the dispersion, flow and HT
Enhanced Nanofluid Thermal
Conductivity
Thermal Conductivity Ratio knf/kbase
 Nanofluids containing <10 nm diameter
copper (Cu) nanoparticles show much higher
TC enhancements than nanofluids containing
metal-oxide nanoparticles of average
diameter 35 nm.
 Volume fraction is reduced by one order of
magnitude for Cu nanoparticles as compared
with oxide nanoparticles for similar TC
enhancement.
 The largest increase in conductivity (up to
Volume Fraction [%]
40% at 0.3 vol.% Cu nanoparticles) was seen
for a nanofluid that contained Cu
nanoparticles coated with thioglycolic acid.
Thermal conductivity enhancement of
copper, copper oxide, and alumina
particles in ethylene glycol.
Appl. Phys. Lett. 78, 718, 2001.
© M. Kostic <www.kostic.niu.edu>
 A German research group has also used metal
nanoparticles (NPs) in fluids, but these NPs
settled. The ANL innovation was depositing
small and stable metal nanoparticles into
base fluids by the one-step directevaporation method.
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Insulated and
vertically-adjustable boat-heater
evaporator
Rotating drum with
moving nanofluid film
Nitrogen
cooling plate with coils and fins
© M. Kostic <www.kostic.niu.edu>
FIG. 2: Proposed improvements for the one-step,
direct-evaporation nanofluid production apparatus
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Nanofluid’s TC: Errors
© M. Kostic <www.kostic.niu.edu>
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Nanofluid’s TC:
CFD & Limits
© M. Kostic <www.kostic.niu.edu>
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Objective:
© M. Kostic <www.kostic.niu.edu>
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Conclusion (1):
© M. Kostic <www.kostic.niu.edu>
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Conclusion (2)
© M. Kostic <www.kostic.niu.edu>
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For further Info
you may contact Prof. Kostic at:
[email protected]
or on the Web:
www.kostic.niu.edu
Prof. M. Kostic
Mechanical Engineering
NORTHERN ILLINOIS UNIVERSITY
© M. Kostic <www.kostic.niu.edu>
080125