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Micro
Micro
-
-
and Nano
and Nano
-
-
Scale
Scale
Heat Transfer
Heat Transfer
Research at UTA
Research at UTA
Prof. Seung M. You Prof. Seung M. You
Micro Micro- -Scale Heat Transfer Lab Scale Heat Transfer Lab
The University of Texas at Arlington The University of Texas at Arlington
Mechanical & Aerospace Engineering Department Mechanical & Aerospace Engineering Department
Laboratory Introduction
Laboratory Introduction
The Micro The Micro- -Scale Heat Transfer Scale Heat Transfer
Laboratory at UTA is fully Laboratory at UTA is fully
equipped for conducting equipped for conducting
experimental investigations of experimental investigations of
boiling/ condensation heat boiling/ condensation heat
transfer and two transfer and two- -phase flow. phase flow.
Investigations in both
fundamental and applied
research areas primarily
focus on the enhancement
of heat transfer using
phase-change phenomena.
Critical heat flux in saturated water
Faculty : Professor S. M. You
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Pool Boiling Test Section Pool Boiling Test Section
Flow Boiling Test Loop Flow Boiling Test Loop
Condensation Test Section Condensation Test Section
Micro Micro- -Channel Test Section Channel Test Section
Contact Resistance Test Section Contact Resistance Test Section
High Speed Digital Video Camera High Speed Digital Video Camera
Pool Boiling Test Section
Flow Boiling Test Loop Condensation Test Section
Laboratory Facilities
Laboratory Facilities
Fundamental Studies
N
u
c
l
e
a
t
e
b
o
il
in
g
H
e
a
t
F
l
u
x
Wall Superheat
Vapor Mushroom
Region
qDIB
qCHF
qDNB
Discrete Bubble
Region
qINC
First Transition
Region
Second Transition
Region
Natural Convection
Region
Critical Heat Flux
Ordered departures
Chaotic departures
Burnout
Fundamentals of Boiling
Fundamentals of Boiling
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Film Boiling Characteristics Film Boiling Characteristics - - Experimental & Numerical Analysis Experimental & Numerical Analysis
Fundamentals of Boiling
Fundamentals of Boiling
Microporous Coating
Microporous Coating
The excellent performance of microporous
coating results from an increase in both the
number of nucleation sites and bubble
departure frequency per site. These increases
were achieved by forming microscale cavities
on the surface.
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Microporous Coating (SEM)
Microporous Coating (SEM)
ABM CBM DOM
Top view
Side view
Conductive
Conductive
Microporous Coating
Microporous Coating
Multi-stage Electroplating Technique
High Current Flux Electroplating
Low Current Flux Electroplating
0 10 20 30
Superheat(K)
0
50
100
150
200
250
H
e
a
t
F
l
u
x
q
"
(
1
0
4
W
/
m
2
)
Plating0.33A/cm
2
15S
Plating0.33A/cm
2
20S
Plating0.33A/cm
2
25S
Plain
169.0
173.8175.9
141.2
Ideal for various fluids
including water
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SEM image for 8-12 m 40-60 m 100-150 m
Surface Images of
Conductive Microporous Coatings
Electroplated surfaces
Condensation Heat Transfer
Condensation Heat Transfer
Enhancement
Enhancement
Test apparatus to study the
condensation heat transfer of a
quiescent vapor
Effect of roughness
Effect of surface tension
Effect of extended surface
Effect of fluid flow
Combined effects
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Boiling Heat Transfer in
Boiling Heat Transfer in
Nanofluids
Nanofluids
10
0
10
1
10
2
10
3
10
0
10
1
10
2
10
3
10
4
Pure water 2.89 psi
Nanofluid (0.001 g/l)
Nanofluid (0.005 g/l)
Nanofluid (0.01 g/l)
Nanofluid (0.025 g/l)
Nanofluid (0.05 g/l)
T
sat
(C)
q
"
(
k
W
/
m
2
)
CHF (pure water)
CHF (nanofluid, 0.001g/l )
CHF ( >0.001 g/l )
Conducted by Argonne National Lab.
200 % increase in Critical Heat Flux
100 kW/m
2
200 kW/m
2
300 kW/m
2
100 kW/m
2
200 kW/m
2
3mm
3mm
300 kW/m
2
Boiling Heat Transfer in
Boiling Heat Transfer in
Nanofluids
Nanofluids
Water
Nanofluids
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10
0
10
1
10
2
10
3
T
sat
(C)
10
0
10
1
10
2
10
3
10
4
q
"
(
k
W
/
m
2
)
0 days
10, 20 &30 days
10 days -->1830 kW/m
2
20 days -->1820 kW/m
2
30 days -->1800 kW/m
2
0 days -->1530 kW/m
2
Reliability of Nanofluids
30-day reliability test shows
NO degradation of CHF
enhancement for nanofluids.
This means nanoparticles do
not sink or agglomerate once it
is fully dispersed.
Nanofluid Pure water
Micro
Micro
-
-
Channel Flow Boiling
Channel Flow Boiling
Cooling of Aircraft Phased-Array Radar
Micro-channel provides significant
improvement for the uniform
surface temperature distribution
and high-power heat dissipation
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Liquid Cooling for Future PC Liquid Cooling for Future PC s s
High efficiency cooling module for future high-heat-flux
electronic devices
~200 W was dissipated from
1 cm
2
chip at 100
o
C
Contact Resistance
Contact Resistance
Thermal Interface Resistance - due
to imperfect contact between the
mating two surfaces
Solid-solid contact is less
than 10% of true area.
