The heat fluxes from electronic components are steadily increasing and have now, in some applications, reached levels where air-cooling is no longer sufficient. One alternative solution, which has received much attention during the last decade, is to use heat pipes or thermosyphons for transferring or spreading the dissipated heat. In this paper two-phase thermosyphon loops are discussed. Especially, the choice of fluid and its influence on the design and performance is treated. The discussion is supported by results from simulations concerning heat transfer and pressure drop. In general it is found that high-pressure fluids will give better performance and more compact designs as high-pressure results in higher boiling heat transfer coefficients and smaller necessary tube diameter.

1.
Palm, B., and Tengblad, N., 1996, “Cooling of Electronics by Heat Pipes and Thermosyphons—A Review of Methods and Possibilities,” presented at the National Heat Transfer Conference, Houston, TX, ASME HTD-Vol. 329, Vol. 7, pp. 97–108.
2.
Kishimoto
,
T.
,
1994
, “
Flexible-Heat-Pipe Cooling for High-Power Devices
,”
Int. J. Microcircuits Electron. Packag.
,
17
(
2
), pp.
98
107
.
3.
Gromoll, B., 1993, “Application and Performance of Si-Microcooling System for Electronic Devices,” Proc., Eurotherm Seminar No. 29, Thermal Management of Electronic Systems, pp. 13-1–13-10.
4.
Gromoll, B., 1994, “Advanced Micro Air Cooling Systems for High Density Packaging,” Proc., 10th IEEE Semi-Therm Conference, pp. 53–58.
5.
Kuwahara, H. et al., 1994, “Enhancement of Two-Phase Thermosyphon for Cooling High Heat Flux Power Devices,” Proc., I-Therm IV (InterSociety Conference on Thermal Phenomena in Electronic Systems), Washington, DC, pp. 184–189.
6.
Kishimoto, T., and Harada, A., 1992, “Two-Phase Thermosyphon Cooling for Telecom Multichip Modules”, in Advances in Electronic Packaging, Proc., Joint ASME/JSME Conf. on Electronic Packaging, Milpitas, pp. 135–141.
7.
Tengblad, N., and Palm, B., 1995, “Flow Boiling and Film Condensation Heat Transfer in Narrow Channels of Thermosiphons for Cooling of Electronic Components,” Proc., Eurotherm Seminar No. 45, Leuven, Belgium.
8.
Tengblad, N., and Palm, B., 1996, “External Two-Phase Thermosiphons for Cooling of Electronic Components,” Int. J. Microcircuits Electron. Packag., 19(1).
9.
Khodabandeh
,
R.
, and
Palm
,
B.
,
2002
, “
An Experimental Investigation of the Influence of Threaded Surface on the Boiling Heat Transfer Coefficients in Vertical Narrow Channels
,”
Microscale Thermophys. Eng.
6
(
2
), pp.
131
139
.
10.
Khodabandeh
,
R.
, and
Palm
,
B.
,
2002
, “
An Experimental Investigation of the Influence of System Pressure on the Boiling Heat Transfer Coefficient in a Closed Two-Phase Thermosyphon Loop
,”
Int. J. Thermal Sciences
,
41
, pp.
619
624
.
11.
Incropera, F. P., 1990, “Liquid Immersion Cooling of Electronic Components,” Heat Transfer in Electronic and Microelectronic Equipment, ed., A. E. Bergles, Hemisphere Publishing Corp., pp. 407–444.
12.
Nakayama, W., and Bergles, A. E., 1990, “Cooling of Electronic Equipment: Past Present and Future,” Heat Transfer in Electronic and Microelectronic Equipment, ed., A. E. Bergles, Hemisphere Publishing Corp., pp. 3–39.
13.
Bergles, A. E., and Bar-Cohen, A., 1990, “Direct Liquid Cooling of Microelectronic Components,” Advances in Thermal Modeling of Electronic Components and Systems, Vol. 2, pp. 233–342.
14.
Bar-Cohen
,
A.
,
1993
, “
Thermal Management of Electronic Components with Dielectric Liquids
,”
Int. J. JSME, Ser. B
,
36
(
1
), pp.
1
25
.
15.
Gorenflo, D., 1993, “Pool Boiling,” VDI Heat Atlas, VDI-Verlag GmbH, Dusseldorf, Germany, pp. Ha1–13.
16.
Cooper, M. G., 1984, “Saturation Nucleate Pool Boiling. A Simple Correlation,” Proc., 1st National Conference on Heat Transfer, Vol. 2, pp. 785–793 (I. Chem. E. Symp. Ser. No. 86).
17.
Guglielmini, G., Misale, M., and Schenone, C., 1993, “Pool Boiling Heat Transfer of Dielectric Fluids for Immersion Electronic Cooling: Effects of Pressure,” Proc, Eurotherm Seminar No. 29, Thermal Management of Electronic Systems, pp. 15-1–15-10.
18.
Ko¨berle, K., and Auracher, H., 1993, “Temperature Controlled Measurements of the Critical Heat Flux on Microelectronic Heat Sources in Natural Convection and Jet Impingement Cooling,” Proc., Eurotherm Seminar No. 29, Thermal Management of Electronic Systems, pp. 14-1–14-10.
19.
Lienhard, J. H., and Dhir, V. K., 1973, “Extended Hydrodynamic Theory of the Peak and Minimum Pool Boiling Heat Fluxes,” Report CR-2270, National Aeronautics and Space Administration, Washington DC.
20.
Lienhard
,
J. H.
, and
Dihr
,
V. K.
,
1973
, “
Peak Boiling Heat Flux from Finite Bodies
,”
ASME J. Heat Transfer
,
95
, p.
152
152
.
21.
Hewitt, G. F., Shires, G. L., and Bott, T. R., 1994, Process Heat Transfer, CRC Press/Begell House, ISBN 0-8493-9918-1.
22.
Klein, S. A., and Alvarado, F. L., 1998, Engineering Equation Solver, Ver. 5.2, F-Chart Software, www.fChart.com.
23.
NIST, 1998, Refprop, NIST Standard Reference Database 23, Ver 6.01.
24.
Lockhart
,
R. W.
, and
Martinelli
,
R. C.
,
1949
, “
Proposed Correlation of Data for Isothermal Two-Phase Two-Component Flow in Pipes
,”
Chem. Eng. Prog.
,
45
(
1
),
39
48
.
25.
Collier, J. G., 1972, Convective Boiling and Condensation, 2nd Edition, McGraw-Hill.
26.
Liu
,
Z.
, and
Winterton
,
R. H. S.
,
1991
, “
A General Correlation for Saturated and Subcooled Flow Boiling in Tube and Annuli, Based on Nucleate Pool Boiling Equation
,”
Int. J. Heat Mass Transf.
,
34
, pp.
2759
2766
.
You do not currently have access to this content.