Due to the increase in energy prices and spiralling consumption, there is a need to greatly reduce the cost of electricity within data centers, where it makes up to 50% of the total cost of the IT infrastructure. A technological solution to this is using on-chip cooling with a single-phase or evaporating liquid to replace energy intensive air-cooling. The energy carried away by the liquid or vapor can also potentially be used in district heating, as an example. Thus, the important issue here is “what is the most energy efficient heat removal process?” As an answer, this paper presents a direct comparison of single-phase water, a 50% water–ethylene glycol mixture and several two-phase refrigerants, including the new fourth generation refrigerants HFO1234yf and HFO1234ze. Two-phase cooling using HFC134a had an average junction temperature from 9 to 15 °C lower than for single-phase cooling, while the required pumping power for the central processing unit cooling element for single-phase cooling was on the order of 20–130 times higher to achieve the same junction temperature uniformity. Hot-spot simulations also showed that two-phase refrigerant cooling was able to adjust to local hot-spots because of flow boiling’s dependency on the local heat flux, with junction temperatures being 20 to 30 °C lower when compared to water and the 50% water–ethylene glycol mixture, respectively. An exergy analysis was developed considering a cooling cycle composed by a pump, a condenser, and a multimicrochannel cooler. The focus was to show the exergetic efficiency of each component and of the entire cycle when the subject energy recovery is considered. Water and HFC134a were the working fluids evaluated in such analysis. The overall exergetic efficiency was higher when using HFC134a (about 2%), and the exergy destroyed, i.e., irreversibilities, showed that the cooling cycle proposed still have a huge potential to increase the thermodynamic performance.

References

References
1.
EPA, 2007, Report to Congress on Server and Data Center Energy Efficiency Public Law 109-431, U.S. Environmental Protection Agency.
2.
Larson
,
J. B.
, 2009, America’s Energy Security Trust Fund Act of 2009, in H.R. 1337.
3.
Koomy
,
J. G.
, 2007,
Estimating Regional Power Consumption by Servers: A Technical Note
,
Lawrence Berkeley National Laboratory
,
Oakland, CA
.
4.
IBM, 2007,
IBM Unveils Plan to Combat Data Center Energy Crisis
; Allocates $1 Billion to Advance “Green” Technology and Services, http://www-03.ibm.com/press/us/en/pressrelease/21524.wsshttp://www-03.ibm.com/press/us/en/pressrelease/21524.wss
5.
Leonard
,
P. L.
, and
Phillips
,
A. L
, 2005, “
The Thermal Bus Opportunity—A Quantum Leap in Data Center Cooling Potential
,”
ASHRAE Transactions
,
Denver
,
CO
.
6.
Saini
,
M.
, and
Webb
,
R. L.
, 2003, “
Heat Rejection Limits of Air Cooled Plane Fin Heat Sinks for Computer Cooling
,”
IEEE Trans. Compon. Packag. Technol.
,
26
(
1
), pp.
71
79
.
7.
Ellsworth
,
M. J.
, Jr.
, and
Simons
,
R. E.
, 2005, “
High Powered Chip Cooling—Air and Beyond
,”
Electron. Cooling
,
11
(
3
), pp.
14
22
.http://www.electronics-cooling.com/2005/08/high-powered-chip-cooling-air-and-beyond/http://www.electronics-cooling.com/2005/08/high-powered-chip-cooling-air-and-beyond/
8.
CMOSAIC, 2010, “
3D Stacked Architectures with Interlayer Cooling
,” http://esl.epfl.ch/page78902-en.htmlhttp://esl.epfl.ch/page78902-en.html
9.
Brunschwiler
,
T.
,
Smith
,
B.
,
Ruetsche
,
E.
, and
Michel
,
B.
, 2009, “
Toward Zero-Emission Data Centers Through Direct Reuse of Thermal Energy
,”
IBM J. Res. Dev.
,
53
(
3
), pp.
11:1
11:13
.
10.
Chu
,
R. C.
,
Simons
,
R. E.
,
Ellsworth
,
M. J.
,
Schmidt
,
R. R.
, and
Cozzolino
,
V.
, 2004, “
Review of Cooling Technologies for Computer Products
,”
IEEE Trans. Device Mater. Reliability
,
4
(
4
), pp.
568
585
.
11.
Agostini
,
B.
,
Fabbri
,
M.
,
Park
,
J. E.
,
Wojtan
,
L.
,
Thome
,
J. R.
, and
Michel
,
B.
, 2007, “
State-of-the-Art of High Heat Flux Cooling Technologies
,”
Heat Transfer Eng.
,
28
, pp.
258
281
.
12.
Celata
,
G. P.
,
Cumo
,
M.
,
Guglielmi
,
M.
, and
Zummo
,
G.
, 2002, “
Experimental Investigation of Hydraulic and Single-Phase Heat Transfer in 0.130-mm Capillary Tube
,”
Nanoscale Microscale Thermophys. Eng.
,
6
, pp.
85
97
.
13.
Celata
,
G. P.
,
Morini
,
G. L.
,
Marconi
,
V.
,
McPhail
,
S. J.
, and
Zummo
,
G.
, 2006, “
Using Viscous Heating to Determine the Friction Factor in Microchannels—An Experimental Validation
,”
Exp. Therm. Fluid Sci.
,
30
, pp.
725
731
.
14.
Celata
,
G. P.
,
Cumo
,
M.
,
McPhail
,
S. J.
, and
Zummo
,
G.
, 2006, “
Characterization of Fluid Dynamic Behaviour and Channel Wall Effects in Microtube
,”
Int. J. Heat Fluid Flow
,
27
, pp.
135
143
.
15.
Celata
,
G. P.
,
Cumo
,
M.
,
Marconi
,
V.
,
McPhail
,
S. J.
, and
Zummo
,
G.
, 2006, “
Microtube Liquid Single-Phase Heat Transfer in Laminar Flow
,”
Int. J. Heat Mass Transfer
,
49
, pp.
3538
3546
.
16.
Tuckerman
,
D. B.
, and
Pease
,
R. F. W.
, 1981, “
High-Performance Heat Sinking for VLSI
,”
IEEE Electron. Device Lett.
,
EDL-2
(
2
), pp.
126
129
.
17.
Colgan
,
E. G.
,
Furman
,
B.
,
Gaynes
,
M.
,
Graham
,
W. S.
,
LaBianca
,
N. C.
,
Magerlein
,
J. H.
,
Polastre
,
R. J.
,
Rothwell
,
M. B.
,
Bezama
,
R. J.
,
Choudhary
,
R.
,
Marston
,
K. C.
,
Toy
,
H.
,
Wakil
,
J.
,
Zitz
,
J. A.
, and
Schmidt
,
R. R.
, 2007, “
A Practical Implementation of Silicon Microchannel Coolers for High Power Chips
,”
IEEE Trans. Compon. Packag. Technol.
,
30
(
2
), pp.
218
225
.
18.
Colgan
,
E. G.
,
Furman
,
B.
,
Gaynes
,
M.
,
LaBianca
,
N. C.
,
Magerlein
,
J. H.
,
Polastre
,
R. J.
,
Bezama
,
R. J.
,
Marston
,
K. C.
, and
Schmidt
,
R. R.
, 2007, “
High Performance and Subambient Silicon Microchannel Cooling
,”
ASME J. Heat Transfer
,
129
, pp.
1046
1051
.
19.
Ganapati
,
P.
, 2009, “
Water-Cooled Supercomputer Doubles as Dorm Space Heater
,” available from: http://www.wired.com/gadgetlab/2009/06/ibm-supercomputer/http://www.wired.com/gadgetlab/2009/06/ibm-supercomputer/
20.
Kandlikar
,
S. G.
, 2010, “
Scale Effects on Flow Boiling Heat Transfer in Microchannels: A Fundamental Perspective
,”
Int. J. Therm. Sci.
,
49
(
7
), pp.
1073
1085
.
21.
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
(
3
), pp.
86
93
.
22.
Kandlikar
,
S. G.
, 2004, “
Heat Transfer Mechanisms During Flow Boiling in Microchannels
,”
ASME J. Heat Transfer
,
126
(
1
), pp.
8
17
.
23.
Celata
,
G. P.
,
Saha
,
S. K.
,
Zummo
,
G.
, and
Dossevi
,
D.
, 2010, “
Heat Transfer Characteristics of Flow Boiling in a Single Horizontal Microchannel
,”
Int. J. Therm. Sci.
,
49
(
7
), pp.
1086
1094
.
24.
Bertsch
,
S. S.
,
Groll
,
E. A.
, and
Garimella
,
S. V.
, 2008, “
Refrigerant Flow Boiling Heat Transfer in Parallel Microchannels as a Function of Local Vapor Quality
,”
Int. J. Heat Mass Transfer
,
51
(
19–20
), pp.
4775
4787
.
25.
Harirchian
,
T.
, and
Garimella
,
S. V.
, 2008, “
Microchannel Size Effects on Local Flow Boiling Heat Transfer to a Dielectric Fluid
,”
Int. J. Heat Mass Transfer
,
51
, pp.
3724
3735
.
26.
Lee
,
P. S.
, and
Garimella
,
S. V.
, 2008, “
Saturated Flow Boiling Heat Transfer and Pressure Drop in Silicon Microchannel Arrays
,”
Int. J. Heat Mass Transfer
,
51
(
3–4
), pp.
789
806
.
27.
Liu
,
D.
,
Lee
,
P. S.
, and
Garimella
,
S. V.
, 2005, “
Prediction of the Onset of Nucleate Boiling in Microchannel Flow
,”
Int. Commun. Heat Mass Transfer
,
48
(
25–26
), pp.
5134
5149
.
28.
Bergles
,
A. E.
, and
Kandlikar
,
S. G.
, 2005, “
On the Nature of Critical Heat Flux in Microchannels
,”
ASME J. Heat Transfer
,
127
, pp.
101
107
.
29.
Wang
,
G.
,
Cheng
,
P.
, and
Bergles
,
A. E.
, 2008, “
Effects of Inlet/Outlet Configurations on Flow Boiling Instability in Parallel Microchannels
,”
Int. J. Heat Mass Transfer
,
51
(
9–10
), pp.
2267
2281
.
30.
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
.
31.
Revellin
,
R.
, and
Thome
,
J. R.
, 2008, “
An Analytical Model for the Prediction of the Critical Heat Flux in Heated Microchannels
,”
Int. J. Heat Mass Transfer
,
51
, pp.
1216
1225
.
32.
Park
,
J. E.
,
Thome
,
J. R.,
and
Michel
,
B.
, 2009, “
Effect of Inlet Orifice on Saturated CHF and Flow Visualization in Multi-Microchannel Heat Sinks
,”
Twenty-Fifth Annual Ieee Semiconductor Thermal Measurement and Management Symposium
, pp.
1
8
.
33.
Costa-Patry
,
E.
,
Olivier
,
J. A.,
and
Thome
,
J. R.
, 2010, “
Hot-Spot Effects on Two-Phase Flow of R245fa in 85μm-Wide Multi-Microchannels
,”
16th International Workshop on Thermal Investigations of IC’s and Systems
,
Barcelona
,
Spain
.
34.
Zhang
,
T.
,
Peles
,
Y.
,
Wen
,
J. T.
,
Tong
,
T.
,
Chang
,
J.
,
Prasher
,
R.
, and
Jensen
,
M.K.
, 2010, “
Analysis and Active Control of Pressure-Drop Flow Instabilities in Boiling Microchannel Systems
,”
Int. J. Heat Mass Transfer
,
52
, pp.
2347
2360
.
35.
Zhang
,
T.
,
Wen
,
J. T.
,
Peles
,
Y.
,
Catano
,
J.
,
Zhou
,
R.
, and
Jensen
,
M. K.
, 2010, “
Two-Phase Refrigerant Flow Instability Analysis and Active Control in Transient Electronics Cooling Systems
,”
Int. J. Multiphase Flow
,
37
(
1
), pp.
84
97
.
36.
Park
,
J. E.
, 2008, “
Critical Heat Flux in Multi-Microchannel Copper Elements With Low Pressure Refrigerants
,” Ph.D. thesis, École Polytechnique Fédérale de Lausanne, Switzerland.
37.
Madhour
,
Y.
,
Olivier
,
J. A.
,
Costa-Patry
,
E.
,
Paredes
,
S.
,
Michel
,
B.
, and
Thome
,
J. R.
, 2011, “
Flow Boiling of R134a in a Multi-Microchannel Heat Sink With Hotspot Heaters for Energy-Efficient Microelectronic CPU Cooling Applications
,”
IEEE Trans. Compon. Packag. Technol.
,
1
(
6
), pp.
873
883
.
38.
Lemmon
,
E.
,
Huber
,
M.
, and
McLinden
,
M.
, 2007,
NIST Standard Reference Database 23: Reference Fluid Thermodynamic and Transport Properties-REFPROP
,
S.R.D. National Institute of Standards and Technology and Program
,
Gaithersburg, MD
.
39.
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
(
14–16
), pp.
3387
3401
.
40.
Cioncolini
,
A.
,
Thome
,
J. R.
, and
Lombardi
,
C.
, 2009, “
Unified Macro-to-Microscale Method to Predict Two-Phase Frictional Pressure Drops of Annular Flows
,”
Int. J. Multiphase Flow
,
35
, pp.
1138
1148
.
41.
Müller-Steinhagen
,
H.
, and
Heck
,
K.
, 1986, “
A Simple Friction Pressure Drop Correlation for Two-Phase Flow in Pipes
,”
Chem. Eng. Prog.
,
20
, pp.
297
308
.
42.
Ong
,
C. L.
, 2010, “
Macro-to-Microchannel Transition in Two-Phase Flow and Evaporation
,”
Ph.D. thesis
,
École Polytechnique Fédérale de Lausanne
, Switzerland.
43.
Ribatski
,
G.
,
Wojtan
,
L.
, and
Thome
,
J. R.
, 2006, “
An Analysis of Experimental Data and Prediction Methods for Two-Phase Frictional Pressure Drop and flow Boiling Heat Transfer in Micro-Scale Channels
,”
Exp. Therm. Fluid Sci.
,
31
, pp.
1
19
.
44.
Shah
,
R. K.,
and
London
,
A. L.
, 1978,
Laminar Flow Forced Convection in Ducts
,
Academic
,
New York
.
45.
Thome
,
J. R.
, 2009,
Engineering Data Book III
,
Wolverine Tube, Inc.
,
Huntsville, AL
.
47.
Kyoto
Protocol
, 1998,
United Nations Framework Convention on Climate Change
. http://www.unfccc.inthttp://www.unfccc.int
48.
Nielsen
,
O. J.
,
Javadi
,
M. S.
,
Sulbaek
,
M. P.
,
Hurley
,
M. D.
,
Wallington
,
T. J.
, and
Singh
,
R.
, 2007, “
Atmospheric Chemistry of CF3CF=CH2: Kinetics and Mechanisms of Gas-Phase Reactions With Cl Atoms, OH Radicals, and O3
,”
Chem. Phys. Lett.
,
439
, pp.
18
22
.
49.
Søndergaard
,
R.
,
Nielsen
,
O. J.
,
Hurley
,
M. D.
,
Wallington
,
T. J.
, and
Singh
,
R.
, 2007, “
Atmospheric Chemistry of Trans-CF3CH=CHF: Kinetics of the Gas-Phase Reactions With Cl Atoms, OH Radicals, and O3
,”
Chem. Phys. Lett.
,
443
, pp.
199
204
.
50.
Brown
,
J. S.
,
Zilio
,
C.
, and
Cavallini
,
A.
, 2010, “
Thermodynamic Properties of Eight Fluorinated Olefins
,”
Int. J. Refrigeration
,
33
, pp.
235
241
.
51.
Agostini
,
B.
,
Revellin
,
R.
,
Thome
,
J. R.
,
Fabbri
,
M.
,
Michel
,
B.
,
Calmi
,
D.
, and
Kloter
,
U.
, 2008, “
High Heat Flux Flow Boiling in Silicon Multi-Microchannels—Part III: Saturated Critical Heat Flux of R236fa and Two-Phase Pressure Drops
,”
Int. J. Heat Mass Transfer
,
51
(
21–22
), pp.
5426
5442
.
52.
Olivier
,
J. A.
,
Marcinichen
,
J. B.
, and
Thome
,
J. R.
, 2010, “
Two-Phase Cooling of Datacenters: Reduction in Energy Costs and Improved Efficiencies
,”
13th Brazilian Congress of Thermal Sciences and Engineering—ENCIT
2010,
Uberlandia
,
MG, Brazil
.
53.
Moran
,
M. J.
,
Howard
,
I.
, and
Shapiro
,
N.
, eds., 2010,
Fundamentals of Engineering Thermodynamics
,
6th ed.
,
John Wiley & Sons
,
New York
, pp.
1
725.
54.
Rosen
,
M. A.
,
Dincer
,
I.
, and
Kanoglu
,
M.
, 2008, “
Role of Exergy in Increasing Efficiency and Sustainability and Reducing Environmental Impact
,”
Energy Policy
,
36
, pp.
128
137
.
55.
Karajgikar
,
S.
,
Agonafer
,
D.
,
Ghose
,
K.
,
Sammakia
,
B.
,
Amon
,
C.
, and
Refai-Ahmed
,
G.
, 2010, “
Multi-Objective Optimization to Improve Both Thermal and Device Performance of a Nonuniformly Powered Micro-Architecture
,”
ASME J. Electron. Packag.
,
132
, pp.
81
87
.
57.
Agostini
,
B.
, and
Thome
,
J. R.
, 2005, “
Comparison of an Extented Database for Flow Boiling Heat Transfer Coefficients in Multi-Microchannels Elements With the Three-Zone Model
,”
ECI Heat Transfer and Fluid Flow in Microscale
,
Castelvecchio Pascoli
,
Italy
.
58.
Ong
,
C. L.
, and
Thome
,
J. R.
, 2011, “
Macro-to-Microchannel Transition in Two-Phase Flow: Part 2—Flow Boiling Heat Transfer and Critical Heat Flux
,”
Exp. Therm. Fluid Sci.
,
35
(
6
), pp.
873
886
.
You do not currently have access to this content.