Servers cooling themselves: Perspective on
Adsorption Cooling for Data Centers
Matthias Hoene
8th European HPC infrastructure Workshop
Mendrisio, April 5, 2017
1
For a long time, cooling computers was not an issue…
2
Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Business case and practical example
3
Adsorption is the method of using solid materials
for cooling via evaporation
Adsorption Evaporation
(e.g. 27°C) (e.g. 16°C)
Left Module
Desorption
(e.g. 55°C)
Condensation
(e.g. 27°C)
•
Water is evaporated using a solid
adsorption material. Evaporation
extracts heat and creates cold
•
Once saturated, the adsorption
material is heated to release the
water
•
Two identical modules operate
phase-shifted to provide
continuous cooling
Right Module
4
Adsorption allows using residual heat for cooling,
as opposed to electricity
Recooler
Condenser
MT
HT
Heat source
15-20
0.55-0.65
Achievable EER / ESEER1
Typical COP2
LT
Evaporator
Object to be cooled
1 EER = Electrical Efficiency Ratio; ESEER = European Seasonal Energy Efficiency Ratio: Ratio of cooling power and electrical power consumed
2 COP = Thermal Coefficient of Performance: Ratio of cooling power output vs. heat power input
5
FAHRENHEIT was spun off from Fraunhofer Institute
to evolve adsorption cooling for practical applications
2002
Founded as SorTech AG in Freiburg as a spinoff of Fraunhofer Institute for Solar Energy
2004
Filed patent on zeolite coating (crystallization)
2008
Filed patent on aluminum phosphate zeolite coating (for lower temperatures)
2009
First international unit deliveries
2013
Launched advanced silica gel based eCoo product line
2017
SorTech relaunched as FAHRENHEIT. Launch of first at-scale zeolite based product line
•
•
•
Run by Walter Mittelbach (founder and CTO) and Matthias Hoene (CEO)
Headquartered in Munich, development and manufacturing in Halle
> 20 patents granted
6
Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Business case and practical example
7
Adsorption cooling is already used in HPC data
centers today
•
•
•
Direct use of processor heat for cooling (via fluid cooling)
Heat source: Hot water cooled computer (in particular HPC)
Chilled water is used for rack cooling
Current specific cooling power
• 8.0 kW/m² (SorTech eCoo 2.0) to
12.0 kW/m² (SorTech eCoo Industry)
8
Current adsorption coolers are almost as efficient as
using free cooling – but without relying on cold weather
Performance of different cooling technologies1
Compression cooling
51%
3.3
Mixed compression &
free cooling
savings vs. free and
compression cooling
verified by experiment
7.6
-51%
Adsorption cooling2
15.4
Free cooling
16.2
0
2
4
6
8
10
12
14
16
Measurements
• Free cooling (hot water cooled
servers)
• Compression cooling (chilled water
cooled storage and switches)
• Adsorption cooling (hot water and
chilled water)
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Coefficient of Performance (COPCold_gen)
1 Measured at a data center in September 2016
2 Total ratio including free cooling and compressor backup
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Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Zeolite crystallization
Low-temperature zeolites
Rack mounting
Business case and practical example
10
Zeolite crystallization enables a step change in performance
compared to standard silica gel
Dissolution
Crystal
Formation
Layer
Growth
Pro
• Advanced working range (heat dissipation temperature down to 40 °C)
• Lower power to weight / volume ratios possible (advanced application range)
• Higher EER (lower electrical energy consumption for recooler – depending on application)
• Faster adsorption cycle (reduced start up time)
Contra
• Lower thermal COP
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With zeolite as adsorbent, the power per area can be
increased significantly
Adsorber modules are becoming smaller
at identical power…
… allowing for increasingly more cooling power in a
smaller footprint
~70
Specific 70
power 60
[kW/m²]
50
37
40
30
20
10
6
8
ACS
(2008)
eCoo
(2013)
0
eCoo XL1
Silica gel based devices
2015
2016
2017 …
1 Special variant for data centers: taller, and hydraulics placed above modules
12
Zeo
(2017+)
Zeolite
based
Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Zeolite crystallization
Low-temperature zeolites
Rack mounting
Business case and practical example
13
At least as significantly, zeolite can be adjusted to the temperature
range of the application, and allows for drive temperatures down to 45°C from CPUs
Relative 25
water
uptake 20
[%]
AlPO-5
15
Silica gel
10
5
0
40
50
60
70
80
90
Desorption temperature Tde [°C]
•
•
Water uptake has to be maximized within the operation range
At temperatures between 45 and 55 °C (waste heat of servers), AlPO-5 is the best option
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Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Zeolite crystallization
Low-temperature zeolites
Rack mounting
Business case and practical example
15
Power density is reaching the point where the adsorption unit can be
rack fitted, which could make hydraulic integration easier
Hot water
2 process
modules
450 mm
Raised floor
Cold water
Recool circuit
Switching unit
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Topics for today
Introduction to adsorption cooling
Current state of the technology
Innovation steps in the pipeline
Business case and practical example
17
At Leibniz Supercomputing Center (LRZ), a significant share of
the IT power consumption is reused to generate cold for cooling
Facts & figures
•
IT compute rack inlet temp.: 45-55°C
•
Adsorption chiller cooling circuit temperature: 21°C
•
Re-cooling circuit temp.: 25°C
•
Avg. driving power (IT): 120kW
•
Avg. cooling power: 50kW (for storage)
•
Cooling liquid: water with anti-corrosive and
anti-bacterial additives
Key results
Current system setup
1.
CooLMUC-2 IT hardware (IBM/Lenovo)
2.
6x SorTech eCoo 2.0 adsorption chillers
3.
12x background storage racks of the
SuperMUC phase 2 supercomputer
4.
Hydraulic system, backup cooling and heat
rejection (hybrid cooling tower)
120kW
50kW
9kW
heat removed from the computer
cold produced for the storage units
electric power consumed incl. pumps/fans
Efficiency measurements
COPT
0.60 (at 50°C entry temp and 25°C recooling)
COPCold_gen 18.31
COPTotal
21.32
1 Total cold generated divided by total electricity intake
2 As of December 2015
SOURCE: Leibniz Rechenzentrum
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For new data centers, the investment in adsorption cooling
pays back in a very short time
Example assuming 900kW computing power and 300kW storage/switches
Cooling infrastructure
IT
Maintenance
UPS, others
Cold generation
Electricity
Investment [1,000 EUR]
Hot fluid
cooling
750
128 878
Total electricity
[MWh/a]
6,833
456 7,288
Running cost/yr.1
[1,000 EUR]
15
1,093
+124
Cold fluid
cooling
600 154 754
Payback
<7 months
1,108
-225
6,833
1,952 8,785 15
1,318
1,333
1 Not taking into account lower power demand charge
SOURCE: Fahrenheit estimates and price data
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Adsorption cooling is a promising element for energy efficient
data centers, with a clear path to the future
• First installations in fluid cooled data centers already reliable and
economic
• Technology is improving as we speak:
• Floor space requirements are becoming smaller
• Rollout of zeolite technology (AlPO-5) leads to both higher efficiency
and better suitability for typical CPU temperatures
• In new data centers, investment case for adsorption cooling is compelling
• Payback via electricity savings on the order of one year
• In existing data centers, case by case evaluation necessary – but typically,
energy savings pay back the investment in a reasonable amount of time
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To add some Olympic spirit…
Citius, altius, fortius
Faster, higher, stronger
Cooler, smaller, cheaper
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