This paper presents the results of an investigation of the thermal performance of a graphite foam thermosyphon evaporator and discusses the foam’s potential for use in the thermal management of electronics. The graphitized carbon foam used in this study is an open-cell porous material that consists of a network of interconnected graphite ligaments whose thermal conductivities are up to five times higher than copper. While the bulk graphite foam has a thermal conductivity similar to aluminum, it has one-fifth the density, making it an excellent thermal management material. Furthermore, using the graphite foam as the evaporator in a thermosyphon enables the transfer of large amounts of energy with relatively low temperature difference and without the need for external pumping. Performance of the system with FC-72 and FC-87 was examined, and the effects of liquid fill level, condenser temperature, and foam height, width, and density were studied. Performance with FC-72 and FC-87 was found to be similar, while the liquid fill level, condenser temperature, geometry, and density of the graphite foam were found to significantly affect the thermal performance. The boiling was found to be surface tension dominated, and a simple model based on heat transfer from the outer surface is proposed. As much as $149W$ were dissipated from a $1cm2$ heated area.

1.
Anderson
,
T. M.
, and
Mudawar
,
I.
, 1989, “
Microelectronic Cooling by Enhanced Pool Boiling of a Dielectric Fluorocarbon Liquid
,”
ASME J. Heat Transfer
0022-1481,
111
, pp.
752
759
.
2.
Mudawar
,
I.
, and
Anderson
,
T. M.
, 1993, “
Optimization of Enhanced Surfaces for High Flux Chip Cooling by Pool Boiling
,”
J. Electron. Packag.
1043-7398
115
, pp.
89
100
.
3.
Ramaswamy
,
C.
,
Joshi
,
Y.
,
Nakayama
,
W.
, and
Johnson
,
W. B.
, 1999, “
Thermal Performance of a Compact Two-Phase Thermosyphon: Response to Evaporator Confinement and Transient Loads
,”
J. Enhanced Heat Transfer
1065-5131,
6
, pp.
279
288
.
4.
Ramaswamy
,
C.
,
Joshi
,
Y.
,
Nakayama
,
W.
, and
Johnson
,
W. B.
, 2000, “
Combined Effects of Sub-Cooling and Operating Pressure on the Performance of a Two-Chamber Thermosyphon
,”
IEEE Trans. Compon., Packag. Technol.
,
23
(
1
), pp.
61
69
.
5.
Ramaswamy
,
C.
,
Joshi
,
Y.
,
Nakayama
,
W.
, and
Johnson
,
W. B.
, 2003, “
Effects of Varying Geometrical Parameters on Boiling from Microfabricated Enhanced Structures
,”
ASME J. Heat Transfer
0022-1481,
125
, pp.
103
109
.
6.
Athreya
,
B. P.
,
Mahajan
,
R. L.
, and
Sett
,
S.
, 2002, “
Pool Boiling of FC-72 Over Metal Foams: Effect of Foam Orientation and Geometry
,”
Proc. of 8th AIAA/ASME Join Thermophysics and Heat Transfer Conference
, Jun 24–26,
St. Louis
, MO, pp. AIAA
2002
3214
.
7.
Gulliksen
,
M.
,
Haugerud
,
H.
, and
Kristiansen
,
H.
, 1999, “
Enhanced Boiling Heat Transfer with Porous Silver Coatings for Electronics Cooling
,”
Proc. 5th ASME/JSME Joint Thermal Engineering Conference
, Mar. 15–19,
San Diego
, CA, p.
AJTE99
-
6268
.
8.
Klett
,
J.
,
Hardy
,
R.
,
Romine
,
E.
,
Walls
,
C.
, and
Burchell
,
T.
, 2000, “
High-Thermal-Conductivity, Mesophase-Pitch-Derived Carbon Foams: Effect of Precursor on Structure and Properties
,”
Carbon
0008-6223,
38
, pp.
953
973
.
9.
3M, 2002, Fluorinert Electronic Liquid FC-72 & FC-87 Product Information.
10.
ASM Specialty Handbook: Copper and Copper Alloys
, 2001,
J. R.
Davis
, ed.,
ASM International
, Materials Park, OH, p.
453
.
11.
Hust
,
J. G.
, and
Lankford
,
A. B.
, 1984, “
Thermal Conductivity of Aluminum, Copper, Iron, and Tungsten for Temperatures from 1K to the Melting Point
,” NBSIR-84/3007, pp. 1–16.
12.
Wang
,
K. F.
and
Dybbs
,
A.
, 1976, “
An Experimental Study of Thermal Equilibrium in Liquid Saturated Porous Media
,”
,
19
, pp.
234
235
.
13.
Poco Graphite Inc.
, 2000, PocoFoam Product Information.