Heat transfer coefficients and bubble motion characteristics are reported for two-phase water flow in an array of 13 equally spaced microchannels over an area of 1 cm2. Each channel has Dh = 451 ± 38 μm, W/H = 0.8, and L/Dh = 22.2. Uniform heat flux is applied through the base, and wall temperatures are determined from the thermocouple readings corrected for heat conduction effects. The upper surface is insulated and transparent. Single-phase heat transfer coefficients are in a good agreement with comparable trends of existing correlations for developing flow and heat transfer, although a difference is seen due to the insulated upper surface. Two-phase heat transfer coefficients and flow characteristics are determined for 221 < G < 466 kg/m2s and 250 < q < 1780 kW/m2. Heat transfer coefficients normalized with mass flux exhibit a trend comparable to that of available studies that use similar thermal boundary conditions. Flow visualization shows expanding vapor slug flow as the primary flow regime with nucleation and bubbly flow as the precursors. Analysis of bubble dynamics reveals ∼t1/3 dependence for bubble growth. Flow reversal is observed and quantified, and different speeds of the vapor phase fronts are quantified at the leading and trailing edges of vapor slugs once the bubble diameter equals the channel width. Bubble formation, growth, coalescence, and detachment at the outlet of the array are best characterized by the Weber number.

References

References
1.
Tuckerman
,
D. B.
, and
Pease
,
R. F. W.
, 1981, “
High-Performance Heat Sinking for VLSI
,”
IEEE Electron Device Lett.
,
EDL-2
(
5
), pp.
126
129
.
2.
Judy
,
J.
,
Maynes
,
D.
, and
Webb
,
B. W.
, 2002, “
Characterization of Frictional Pressure Drop for Liquid Flows Through Microchannels
,”
Int. J. Heat Mass Transfer
,
45
, pp.
3477
3489
.
3.
Qu
,
W.
,
Mudawar
,
I.
,
Lee
,
S. Y.
, and
Wereley
,
S. T.
, 2006, “
Experimental and Computational Investigation of Flow Development and Pressure Drop in a Rectangular Microchannel
,”
ASME J. Electron. Packag.
,
128
, pp.
1
9
.
4.
Harms
,
T. M.
,
Kazmierczak
,
M. J.
, and
Gerner
,
F. M.
, 1999, “
Developing Convective Heat Transfer in Deep Rectangular Microchannels
,”
Int. J. Heat Fluid Flow
,
20
, pp.
149
157
.
5.
Lee
,
P. S.
, and
Garimella
,
S. V.
, 2006, “
Thermally Developing Flow and Heat Transfer in Rectangular Microchannels of Different Aspect Ratios
,”
Int. J. Heat Mass Transfer
,
49
, pp.
3060
3067
.
6.
Plesset
,
M. S.
, and
Zwick
,
S. A.
, 1954, “
The Growth of Vapour Bubbles in Superheated Liquids
,”
J. Appl. Phys.
,
25
, pp.
493
500
.
7.
Kandlikar
,
S. G.
, 1990, “
A General Correlation for Two-Phase Flow Boiling Heat Transfer Coefficient Inside Horizontal and Vertical Tubes
,”
ASME J. Heat Transfer
,
102
, pp.
219
228
.
8.
Qu
,
W.
, and
Mudawar
,
I.
, 2002, “
Transport Phenomena in Two-Phase Micro-channel Heat Sinks
,”
ASME J. Electron. Packag.
,
126
, pp.
213
224
.
9.
Steinke
,
M.
, and
Kandlikar
,
S. G.
, 2004, “
An Experimental Investigation of Flow Boiling Characteristics of Water in Parallel Microchannels
,”
ASME J. Heat Transfer
,
126
, pp.
518
526
.
10.
Balasubramanian
,
P.
, and
Kandlikar
,
S. G.
, 2005, “
Experimental Study of Flow Patterns, Pressure Drop, and Flow Instabilities in Parallel Rectangular Microchannels
,”
Heat Transfer Eng.
,
26
, pp.
20
27
.
11.
Cortina Diaz
,
M.
, and
Schmidt
,
J.
, 2007, “
Experimental Investigation of Transient Boiling in Microchannels
,”
Int. J. Heat Fluid Flow
,
28
, pp.
95
102
.
12.
Thome
,
J. R.
,
Dupont
,
V.
, and
Jacobi
,
A. M.
, 2004, “
Heat Transfer Model for Evaporation in Microchannels. Part I: Presentation of the Model
,”
Int. J. Heat Mass Transfer
,
47
, pp.
3375
3385
.
13.
Dupont
,
V.
,
Thome
,
J. R.
, and
Jacobi
,
A. M.
, 2004, “
Heat Transfer Model for Evaporation in Microchannels. Part II: Comparison With the Database
,”
Int. J. Heat Mass Transfer
,
47
, pp.
3387
3401
.
14.
Kandlikar
,
S. G.
, and
Balasubramanian
,
P.
, 2004, “
An Extension of the Flow Boiling Correlation to Transition, Laminar, and Deep Laminar Flows in Minichannels and Microchannels
,”
Heat Transfer Eng.
,
25
, pp.
86
93
.
15.
Peters
,
K. H.
, and
Kulacki
,
F. A.
, 2005, “
Flow Boiling in Microchannels
,”
Proceedings, National Heat Transfer Conference
,
ASME
,
New York
, Paper No. HT2005-72036.
16.
Kandlikar
,
S.
, 2004, “
Heat Transfer Mechanisms During Flow Boiling in Microchannels
,”
ASME J. Heat Transfer
,
126
, pp.
8
16
.
17.
Lagus
,
T.
, 2007, “
Single- and Two-Phase Forced Convection in an Array of Parallel Microchannels
,” Master’s thesis in Mechanical Engineering, University of Minnesota, Minneapolis, MN.
18.
Hetsroni
,
G.
,
Gurevich
,
M.
,
Moysak
,
A.
,
Pogrebnyak
,
E.
,
Rozenblit
,
R.
, and
Yarin
,
L.
, 2003, “
Boiling in Capillary Tubes
,”
Int. J. Multiphase Flow
,
29
, pp.
1551
1563
.
19.
Thorncroft
,
G. E.
,
Klausner
,
J. F.
, and
Mei
,
R.
, 1998, “
An Experimental Investigation of Bubble Growth and Detachment in Vertical Upflow and Downflow Boiling
,”
Int. J. Heat Mass Transfer
,
41
, pp.
3857
3871
.
20.
Peles
,
Y.
, 2003, “
Two-Phase Flow in Microchannels—Instabilities Issues and Flow Regime Mapping
,”
ICCM2003-1059, Proceedings, First International Conference on Microchannels and Minichannels
,
S. G.
Kandlikar
, ed.,
ASME
,
New York
, Vol.
1
, pp.
559
566
.
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