Thermal management of modern electronics is rapidly becoming a critical bottleneck of their computational performance. Air-cooled heat sinks offer ease and flexibility in installation and are currently the most widely used solution for cooling electronics. We report the characterization of a novel loop heat pipe (LHP) with a wick in the condenser, developed for the integration into an air-cooled heat sink. The evaporator and condenser are planar (102 mm × 102 mm footprint) and allow for potential integration of multiple, stacked condensers. The condenser wick is used to separate the liquid and vapor phases during condensation by capillary menisci and enables the use of multiple condensers with equal condensation behavior and performance. In this paper, the thermal–fluidic cycle is outlined, and the requirements to generate capillary pressure in the condenser are discussed. The LHP design to fulfill the requirements is then described, and the experimental characterization of a single-condenser version of the LHP is reported. The thermal performance was dependent on the fan speed and the volume of the working fluid; a thermal resistance of 0.177  °C/W was demonstrated at a heat load of 200 W, fan speed of 5000 rpm and fluid volume of 67 mL. When the LHP was filled with the working fluid to the proper volume, capillary pressure in the condenser was confirmed for all heat loads tested, with a maximum of 3.5 kPa at 200 W. When overfilled with the working fluid, the condenser was flooded with liquid, preventing the formation of capillary pressure and significantly increasing the LHP thermal resistance. This study provides the detailed thermal–fluidic considerations needed to generate capillary pressure in the condenser for controlling the condensation behavior and serves as the basis of developing multiple-condenser LHPs with low thermal resistance.

References

References
1.
Staats
,
W. L.
,
2012
, “
Active Heat Transfer Enhancement in Integrated Fan Heat Sinks
,” Ph.D. thesis, Massachusetts Institute of Technology, Cambridge, MA.
2.
Peters
,
T. B.
,
Mccarthy
,
M.
,
Allison
,
J.
,
Domínguez Espinosa
,
F. A.
,
Jenicek
,
D.
,
Kariya
,
H. A.
,
Staats
,
W. L.
,
Brisson
,
J. G.
, and
Wang
,
E. N.
,
2012
, “
Design of an Integrated Loop Heat Pipe Air-Cooled Heat Exchanger for High Performance Electronics
,”
IEEE Trans. Compon., Packag., Manuf. Technol.
,
2
(
10
), pp.
1637
1648
.10.1109/TCPMT.2012.2207902
3.
Kariya
,
H. A.
,
Staats
,
W. L.
,
Hanks
,
D. F.
,
Peters
,
T. B.
,
Cleary
,
M.
,
Brisson
,
J. G.
, and
Wang
,
E. N.
,
2012
, “
Scaling of the Performance of an Air-Cooled Heat Pipe With the Addition of Multiple Modular Condensers
,”
IEEE Intersociety Conference on Thermal and Thermomechanical Phenomena in Electronic Systems
,
San Diego, CA, May 30–June 1
.
4.
Reay
,
D.
, and
Kew
,
P.
,
2006
,
Heat Pipes, Fifth Edition: Theory, Design and Applications
,
Elsevier
,
Oxford, UK
.
5.
Peterson
,
G. P.
,
1994
,
An Introduction to Heat Pipes: Modeling, Testing, and Applications
,
Wiley
,
New York
.
6.
Faghri
,
A.
,
1995
,
Heat Pipe Science and Technology
,
Taylor and Francis
,
New York
.
7.
Chi
,
S. W.
,
1976
,
Heat Pipe Theory and Practice
,
McGraw-Hill
,
New York
.
8.
Vasiliev
,
L. L.
,
2005
, “
Heat Pipes in Modern Heat Exchangers
,”
Appl. Therm. Eng.
,
25
(
1
), pp.
1
19
.10.1016/j.applthermaleng.2003.12.004
9.
Maydanik
,
Y. F.
,
2005
, “
Loop Heat Pipes
,”
Appl. Therm. Eng.
,
25
(
5–6
), pp.
635
657
.10.1016/j.applthermaleng.2004.07.010
10.
Ku
,
J.
,
1999
, “
Operating Characteristics of Loop Heat Pipes
,”
29th International Conference on Environmental Systems
,
Denver, CO, July 12–15
.
11.
Nagano
,
H.
, and
Ku
,
J.
,
2007
, “
Start-Up Behavior of a Miniature Loop Heat Pipe With Multiple Evaporators and Multiple Condensers
,”
45th Aerospace Sciences Meeting and Exhibit
,
Reno, NV, January 8–11
.
12.
Anderson
,
W. G.
,
Hartenstine
,
J.
,
Ellis
,
M.
,
Montgomery
,
J.
, and
Peters
,
C.
,
2010
, “
Electronics Cooling Using High Temperature Loop Heat Pipes With Multiple Condensers
,”
Power Systems Conference
,
Fort Worth, TX, November 2–4
.
13.
Ku
,
J.
,
Ottenstein
,
L.
, and
Birur
,
G.
,
2004
, “
Thermal Performance of a Multi-Evaporator Loop Heat Pipe With Thermal Masses and Thermal Electrical Coolers,
” 13th International Heat Pipe Conference, Shanghai, China, Sept. 21–25.
14.
Muto
,
M.
,
Murakami
,
M.
,
Nagai
,
H.
,
Ueno
,
S.
, and
Matsuoka
,
M.
,
2002
, “
Thermal Behavior of a Double-Condenser Design Lhp for Monitor of All-Sky X-Ray Image
,”
32nd International Conference on Environmental Systems
,
San Antonio, TX
, July 15–18.
15.
Kim
,
B.-H.
, and
Peterson
,
G. P.
,
2005
, “
Experimental Study of a Reversible Loop Heat Pipe
,”
J. Thermophys. Heat Transfer
,
19
(
4
), pp.
519
526
.10.2514/1.14283
16.
Muraoka
,
I.
,
Ramos
,
F. M.
, and
Vlassov
,
V. V.
,
2001
, “
Analysis of the Operational Characteristics and Limits of a Loop Heat Pipe With Porous Element in the Condenser
,”
Int. J. Heat Mass Transfer
,
44
(
12
), pp.
2287
2297
.10.1016/S0017-9310(00)00259-3
17.
Kariya
,
H. A.
,
Koveal
,
C.
,
Allison
,
J. M.
,
Kelley
,
M.
,
Mccarthy
,
M.
,
Brisson
,
J. G.
, and
Wang
,
E. N.
,
2009
, “
A Capillary-Pumped Loop Heat Pipe With Multi-Layer Microstructured Wicks
,”
International Workshop on Micro and Nanotechnology for Power Generation and Energy Conversion Applications
,
Washington DC, December 1–4
.
18.
Rosenfeld
,
J. H.
, and
Gernert
,
N. J.
,
2008
, “
Life Test Results for Water Heat Pipes Operating at 200 °C to 300 °C
,”
Space Technology and Applications International Forum
,
Albuquerque, NM
, February 10–14.
19.
Pittinato
,
G. F.
,
1978
, “
Hydrogen Gas Generation in Water Heat Pipes
,”
J. Eng. Mater. Technol.
,
100
(
3
), pp.
313
318
.10.1115/1.3443496
20.
Petrick
,
S. W.
,
1972
, “
Hydrogen Gas Generation in Water/Stainless Steel Heat Pipes
,”
Winter Annual Meeting of the American Society of Mechanical Engineers
,
New York, November 26–30
.
21.
Anderson
,
W. G.
,
Dussinger
,
P. M.
,
Bonner
,
R. W.
, and B., S. D.,
2006
, “
High Temperature Titanium/Water and Monel/Water Heat Pipes
,” 4th International Energy Conversion Engineering Conference and Exhibit San Diego, CA, June 26–29.
22.
Kariya
,
H. A.
,
2012
, “
Development of an Air-Cooled, Loop-Type Heat Pipe With Multiple Condensers
,” Ph.D. thesis, Massachusetts Institute of Technology, Cambridge, MA.
23.
Hanks
,
D. F.
,
2012
, “
Design, Fabrication, and Characterization of a Muilti-Condenser Loop Heat Pipe
,” MSc. thesis, Massachusetts Institute of Technology, Cambridge, MA.
24.
Defense Advanced Research Projects Agency
,
2008
, “
Broad Agency Announcement: Microtechnologies for Air-Cooled Exchangers (MACE).
25.
Domínguez Espinosa
,
F. A.
,
2011
, “
Effect of Fabrication Parameters on Thermophysical Properties of Sintered Wicks
,” MSc. thesis, Massachusetts Institute of Technology, Cambridge, MA.
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