Direct spraying of dielectric liquids has been shown to be an effective method of cooling high-power electronics. Recent studies have illustrated that even higher heat transfer can be obtained by adding extended structures, particularly straight fins, to the heated surface. In the current work, spray cooling of high-aspect-ratio open microchannels was explored, which substantially increases the total surface area and allows more residence time for the incoming liquid to be heated by the wall. Five such heat sinks were constructed, and their thermal performance was investigated. These heat sinks featured a projected area of 1.41×1.41cm2, channel width of 360μm, a fin width of 500μm, and fin lengths of 0.25mm, 0.50mm, 1.0mm, 3.0mm, and 5.0mm. The five enhanced surfaces and a flat surface with the same projected area were sprayed with a full cone nozzle using PF-5060 at 30°C and nozzle pressure differences from 1.364.08atm(69121mlmin). In all cases, the enhanced surfaces improved thermal performance compared to the flat surface. Longer fins were found to outperform shorter ones in the single-phase regime. Adding fins also resulted in the onset of two-phase effects (and higher-heat transfer) at lower wall temperatures than the flat surface. The two-phase regime was characterized by a balance between added area, changing flow flux, flow channeling, and added conduction resistance. Spray efficiency calculations indicated that a much larger percentage of the liquid sprayed onto the enhanced surface evaporated than with the flat surface. Fin lengths between 1mm and 3mm appeared to be optimum for heat fluxes as high as 124Wcm2 (based on projected area) and the range of conditions studied.

1.
Yang
,
J. D.
,
Chow
,
L. C.
, and
Pais
,
M. R.
, 1996, “
Nucleate Boiling Heat Transfer in Spray Cooling
,”
ASME J. Heat Transfer
0022-1481,
118
, pp.
668
671
.
2.
Chow
,
L. C.
,
Sehmbey
,
M. S.
, and
Pais
,
M. R.
, 1997, “
High-Heat-Flux Spray Cooling
,”
Annu. Rev. Heat Transfer
1049-0787,
8
, pp.
291
318
.
3.
Estes
,
K. A.
, and
Mudawar
,
I.
, 1995, “
Comparison of Two-Phase Electronic Cooling Using Free Jets and Sprays
,”
ASME J. Electron. Packag.
1043-7398,
117
, pp.
323
332
.
4.
Estes
,
K. A.
, and
Mudawar
,
I.
, 1995, “
Correlation of Sauter Mean Diameter and Critical Heat Flux for Spray Cooling of Small Surfaces
,”
Int. J. Heat Mass Transfer
0017-9310,
38
(
16
), pp.
2985
2996
.
5.
Horacek
,
B.
,
Kim
,
J.
, and
Kiger
,
K.
, 2004, “
Spray Cooling Using Multiple Nozzles: Visualization and Wall Heat Transfer Measurements
,”
IEEE Trans. Device Mater. Reliab.
1530-4388,
4
(
4
), pp.
614
625
.
6.
Horacek
,
B.
,
Kiger
,
K.
, and
Kim
,
J.
, 2005, “
Single Nozzle Spray Cooling Heat Transfer Mechanisms
,”
Int. J. Heat Mass Transfer
0017-9310,
48
(
8
), pp.
1425
1438
.
7.
Chen
,
R.-H.
,
Tan
,
D. S.
,
Lin
,
K.-C.
,
Chow
,
L. C.
,
Griffin
,
A. R.
, and
Rini
,
D. P.
, 2005, “
Droplet and Bubble Dynamics in Saturated FC-72 Spray Cooling
,”
Proc. of 2005 ASME International Mechanical Engineering Congress and Exposition
,
Orlando
, Nov. 5–11, FL, Paper No. IMECE2005-80456.
8.
Pautsch
,
A. G.
, and
Shedd
,
T. A.
, 2005, “
Spray Impingement Cooling With Single- and Multiple-Nozzle Arrays. Part I: Heat Transfer Data Using FC-72
,”
Int. J. Heat Mass Transfer
0017-9310,
48
, pp.
3167
3175
.
9.
Potash
, Jr.,
M.
, and
Wayner
, Jr.,
P. C.
, 1972, “
Evaporation From a Two-Dimensional Extended Meniscus
,”
Int. J. Heat Mass Transfer
0017-9310,
15
, pp.
1851
1863
.
10.
Demiray
,
F.
, and
Kim
,
J.
, 2004, “
Microscale Heat Transfer Measurements During Pool Boiling of FC-72: Effect of Subcooling
,”
Int. J. Heat Mass Transfer
0017-9310,
47
, pp.
3257
3268
.
11.
Tilton
,
D. E.
,
Tilton
,
C. L.
,
Pais
,
M. R.
, and
Morgan
,
M. J.
, 1992, “
High-Flux Spray Cooling in a Simulated Multichip Module
,”
Proc. of 1992 ASME Heat Transfer Conference
,
ASME
,
New York
, HTD-Vol. 206-2, pp.
73
79
.
12.
Ortiz
,
L.
, and
Gonzalez
,
J. E.
, 1999, “
Experiments on Steady-State High Heat Fluxes Using Spray Cooling
,”
Exp. Heat Transfer
0891-6152,
12
, pp.
215
233
.
13.
Kendall
,
C. M.
, and
Holman
,
J. P.
, 1996, “
Spray Cooling Heat-Transfer With Subcooled Trichlorotrifluoroethane (Freon-113) for Vertical Constant Heat Flux Surfaces
,”
Proc. of ASME Heat Transfer Division
, Vol.
2
, HTD-Vol. 333,
ASME
,
New York
, pp.
159
179
.
14.
Chen
,
R. C.
,
Chow
,
L. C.
, and
Navedo
,
J. E.
, 2002, “
Effects of Spray Characteristics on Critical Heat Flux in Subcooled Water Spray Cooling
,”
Int. J. Heat Mass Transfer
0017-9310,
45
, pp.
4033
4043
.
15.
Lin
,
L.
, and
Ponnappan
,
R.
, 2003, “
Heat Transfer Characteristics of Spray Cooling in a Closed Loop
,”
Int. J. Heat Mass Transfer
0017-9310,
46
, pp.
3737
3746
.
16.
Pais
,
M. R.
,
Chow
,
L. C.
, and
Mahefkey
,
E. T.
, 1992, “
Surface Roughness and Its Effects on the Heat Transfer Mechanism in Spray Cooling
,”
ASME J. Heat Transfer
0022-1481,
114
(
1
), pp.
211
219
.
17.
Silk
,
E. A.
,
Kim
,
J.
, and
Kiger
,
K.
, 2005, “
Spray Cooling Trajectory Angle Impact Upon Heat Flux Using a Straight Finned Enhanced Surface
,”
Proc. of HT2005: ASME 2005 Heat Transfer Summer Conference
, July 17–22, San Francisco,
ASME
,
New York
, ASME Paper No. HT2005-72634.
18.
Silk
,
E. A.
,
Kim
,
J.
, and
Kiger
,
K.
, 2006, “
Spray Cooling of Enhanced Surfaces: Impact of Structure Surface Geometry and Spray Axis Inclination
,”
Int. J. Heat Mass Transfer
0017-9310,
49
, pp.
4910
4920
.
19.
Sodtke
,
C.
, and
Stephan
,
P.
, 2005, “
Spray Cooling Heat Transfer on Micro Structured Surfaces
,”
Proc. of 6th World Conference on Experimental Heat Transfer, Fluid Mechanics, and Thermodynamics
, April 17–21, Matsushima, Miyagi, Japan.
20.
Ghodbane
,
M.
, and
Holman
,
J. P.
, 1991, “
Experimental Study of Spray Cooling With Freon-113
,”
Int. J. Heat Mass Transfer
0017-9310,
34
, pp.
1163
1174
.
21.
Rybicki
,
J. R.
, and
Mudawar
,
I.
, 2006, “
Single-Phase and Two-Phase Cooling Characteristics of Upward-Facing and Downward-Facing Sprays
,”
Int. J. Heat Mass Transfer
0017-9310,
49
, pp.
5
16
.
22.
Incropera
,
F. P.
, and
DeWitt
,
D. P.
, 2002,
Fundamentals of Heat and Mass Transfer
,
5th ed.
,
Wiley
,
New York
, p.
133
.
23.
Chen
,
J. C.
, 1966, “
Correlation for Boiling Heat Transfer to Saturated Fluids in Convective Flow
,”
Ind. Eng. Chem. Prod. Res. Dev.
0196-4321,
5
(
3
), pp.
322
339
.
24.
Yoneda
,
Y.
, 1979, “
An Estimation of the Thermodynamic Properties of Organic Compounds in the Ideal Gas State. I. Acyclic Compounds and Cyclic Compounds With a Ring of Cyclopentane, Cyclohexane, Benzene, or Naphthalene
,”
Bull. Chem. Soc. Jpn.
0009-2673,
52
(
5
), pp.
1297
1314
.
25.
Reid
,
R. C.
,
Prausnitz
,
J. M.
, and
Poling
,
B. E.
, 1989,
The Properties of Gases & Liquids
,
4th Ed.
,
McGraw-Hill
,
New York
, pp.
157
167
.
26.
Lemmon
,
E. W.
,
McLinden
,
M. O.
, and
Friend
,
D. G.
, 2005, “
Thermophysical Properties of Fluid Systems
,”
NIST Chemistry WebBook
,
NIST Standard Reference Database Number 69
,
Linstrom
,
P. J.
, and
Mallard
,
W. G.
, eds. June,
National Institute of Standards and Technology
,
Gaithersburg MD
, http://webbook.nist.govhttp://webbook.nist.gov.
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