Experimental Study of Condensation on Micro Grooved Plates
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Transcript of Experimental Study of Condensation on Micro Grooved Plates
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Experimental Study of Condensation on Micro Grooved Plates
R. Barron-jimenez, H. Y. Hu, G. P. PetersonDepartment of Mechanical Engineering
Texas A&M University
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Overview
• Introduction• Experimental System
– Apparatus– Test Plates– Test Conditions
• Results– Overall Condensation Heat Transfer Coefficient– Condensate Removal
• Conclusions
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Micro Grooves
Scientific Interest• Optimum geometry to
take advantage of the surface tension
• Effect of vapor shear during condensation
• Role of gravitational body force during condensation
Applications• Condensate removal
– Thin film• Retain liquid
– Enhance capillary pumping in micro heat pipes
Better understanding of the condensation phenomena
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Experimental Apparatus
Rotameter
CondensateRemovalUnit
Direct -contactCondenser
Thermocouples
GroovedPlate
Observation WindowVapor Tunnel
Boiler
Cooling Base
Cooling Base
Heater
SuperHeater
Heater
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Experimental Apparatus
Grooved Plate
Cooling PassagesCondensateRemoval
Unit
ObservationWindow
VaporTunnel Micro Grooves
Capillary Paper
Thermocouples
Thermocouples
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Experimental Apparatus
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Experimental Apparatus
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Test Plates
L = 25.4 mm
H r
a aS W
I.D. 0 1 2 3 4 5 6W 0 0.41 0.41 0.33 0.63 0.67 0.69[º] 0 60 60 60 45 60 45
a 25.4 2.25 2.59 2.59 2.44 2.46 2.45S 0 0.95 1.79 1.47 1.17 1.13 1.11Hr 0 0.31 0.31 0.21 0.39 0.48 0.60n 0 16 10 12 12 12 12
Dh 0 0.20 0.20 0.14 0.21 0.32 0.33
Micro Grooves Geometry
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Test Plates
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Test Plates
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Test Conditions
• Vapor velocity : 4.14±0.64 m/s
• Re (transition regime) : 3.474*103
• System pressure : 101.35 kPa
• Plate orientation : Horizontal
• Cooling Temperature : 20, 35, 50, or 65ºC
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Test Conditions
20304050607080
Plate location [mm]
20
35
5065
Plate
temp
eratur
e [º
C]
13 44.75 76.5 108.25 137.20
T c [ºC]
Constant Plate Temperature Assumption
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Results
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
30 40 50 60 70 80Plate temperature, T s [ºC]
0
0.14
0.21
0.32
0.33
h [kW
/m2 K]
D h [mm]
Overall Condensation Heat Transfer Coefficient
Plate 5 vs. 3 (W) : 1.75 and 2.9 times larger = 60º vs. 45º : 1.55 better
hmC (T T )
A (T T )p c,out c,in
s v s
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Results
1.0
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
30 40 50 60 70 80Plate temperature [ºC]
0
0.14
0.21
0.32
0.33
h [kW
/m2 K]
D h [mm]
Overall Condensation Heat Transfer Coefficient
0
20
40
60
80
100
120
140
160
33.308 46.142 60.134 72.452Plate temperature [ºC]
0
0.2
0.2
0.14
0.21
0.32
0.33
Unce
rtaint
y [%
]0 0 0
11
1 1
2
2
2
23
3
3
3
4
4
4
45 5 5
56
66
6
Uh
100UC
Um
2 UT
2 U
T Th Cp
p
2
m2
T
c
2
T
v s
2
Average Uh: 52%
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Results
Condensate Removal
Micro grooves in plate 5 are better than smooth surface
0.05
0.1
0.15
0.2
0.25
0.3
0.35
30 40 50 60 70 80Plate temperature [ºC]
00.20.2
0.140.210.320.33
Mea
n con
dens
ate re
mova
l rate
[gr/s
]D h [mm]
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Conclusions
• Data is not conclusive. Further work is recommended
• Large micro grooves with 60º apex angles tend to work better (best performance: Plate 5)
• Tests conditions improve the micro grooves performance
• Micro grooves help to maintain a stable condensation pattern
• Eliminate “wall channel” effect and reduce heat losses
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Two-Phase Heat Transfer Laboratory
Texas A&M University
Questions?
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