U.S. patent application number 16/869361 was filed with the patent office on 2021-03-25 for fluid-cooled data centres without air coinditioning, and methods for operating same.
This patent application is currently assigned to ECUBE COMPUTING GmbH. The applicant listed for this patent is ECUBE COMPUTING GmbH. Invention is credited to Alexander HAUSER, Volker LINDENSTRUTH, Horst STOCKER.
Application Number | 20210092866 16/869361 |
Document ID | / |
Family ID | 1000005253303 |
Filed Date | 2021-03-25 |
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United States Patent
Application |
20210092866 |
Kind Code |
A1 |
LINDENSTRUTH; Volker ; et
al. |
March 25, 2021 |
FLUID-COOLED DATA CENTRES WITHOUT AIR COINDITIONING, AND METHODS
FOR OPERATING SAME
Abstract
Removal of heat generated by IT equipment in a data centre is
facilitated by heat changing units mounted to back sides of open
computer storage racks in which the IT equipment is mounted. One or
more fans in the IT equipment generate an air flow across the IT
equipment, and a heat exchanging unit mounted to the back side of
the rack transfers heat in the air flow to a fluid coolant flowing
through the heat exchanging unit. The heat exchanging unit has an
air back pressure that does not significantly impede the air flow
across the IT equipment, and a low fluid pressure drop for the
fluid coolant, so that a cold air exhaust temperature of air
exiting the heat exchanging unit is less than or equal to the room
air temperature of input air entering the computer rack.
Inventors: |
LINDENSTRUTH; Volker;
(Mainz, DE) ; STOCKER; Horst; (Oberursel, DE)
; HAUSER; Alexander; (Hanau, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ECUBE COMPUTING GmbH |
Kriftel |
|
DE |
|
|
Assignee: |
ECUBE COMPUTING GmbH
Kriftel
DE
|
Family ID: |
1000005253303 |
Appl. No.: |
16/869361 |
Filed: |
May 7, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
14398758 |
Nov 4, 2014 |
10653041 |
|
|
PCT/EP2013/001391 |
May 10, 2013 |
|
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16869361 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 7/20745 20130101;
H05K 7/208 20130101; H05K 7/20836 20130101; H05K 7/20781 20130101;
H05K 7/20718 20130101 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Foreign Application Data
Date |
Code |
Application Number |
May 11, 2012 |
EP |
12003748.6 |
Nov 23, 2012 |
EP |
12007913.2 |
Claims
1. Method for operating a data centre comprising: (i) a building
for housing a multiplicity of racks (202), each rack being an open
rack housing IT equipment, (ii) the racks (202) being an open rack
housing IT equipment (200) (iii) the racks (202) comprise heat
exchanging means (206, 207) being adapted to transfer the heat
generated by the IT equipment to a fluid coolant, said heat
exchanging means being an element of the racks or an element
attached to the racks, preferably being located at the back side or
element of the racks, (iv) at least one first cooling circuit
(203/204), said cooling circuit being a closed cooling circuit,
which is adapted to supply the heat exchanging means (206, 207) of
the racks (202) with a fluid coolant and is further adapted to
convey the heated coolant away from the heat exchanging means (206,
207) of the racks (202) through the reflux of the cooling circuit,
(v) said first cooling circuit (203/204) being connected to a
source providing coldness, said source being located outside the
space housing the multiplicity of racks, (vi) the IT equipment
(200) located in the respective racks (202) having active means,
preferably fans, for cooling parts of the IT equipment (200),
preferably the CPU and/or GPU and/or a storage hardware, said
active means creating an air flow (205) in the rack (202) towards
the heat exchanging means (206, 207) being an element of the racks
or an element attached to the racks, preferably being located at
the back side or element of the racks (202), (vii) said racks (202)
having no other active means, in particular fans, except for those
contained within the aforementioned IT equipment (200), for
creating an air flow (205) in the rack (202) towards the heat
exchanging means (206, 207) being an element of the racks or an
element attached to the racks, preferably being located at the back
side or element of the racks (202), (viii) said building for
housing the multiplicity of racks (202) comprising no other active
means, except for those contained within the aforementioned IT
equipment (200), for creating an guided air flow, (ix) at least one
electrical power input, (x) at least one mean for distributing the
electrical power from the power input to the individual racks,
allowing redundant power supplies in every rack, comprising the
measures (a) providing a fluid coolant from the source providing
coldness to the heat exchanging means (206, 207) of the racks (202)
within the first cooling circuit, said fluid coolant input flow
entering the heat exchanging means (206, 207) having a temperature
of 1K to 5K, preferably 1K to 3K, most preferred 1K to 2K, below
the temperature of the fluid coolant return flow exiting the heat
exchanging means (206, 207) of the racks (202), (b) controlling the
fluid coolant flow within the first cooling circuit (203, 204)
which is adapted to supply the heat exchanging means (206, 207) of
the racks (202) to maintain the temperature of fluid coolant
entering the heat exchanging means (206, 207) of the racks (202)
(input flow) having a temperature of 1K to 5K, preferably 1K to 3K,
most preferred 1K to 2K, below the temperature of the fluid coolant
return flow exiting the heat exchanging means (206, 207) of the
racks (202), (c) conveying the heated fluid coolant leaving the
heat exchanging means (206, 207) of the racks (202) (return flow)
to the source providing coldness, said source being located outside
the space housing the multiplicity of racks, to remove the heat
from the heated fluid coolant to a temperature of 1K to 5K,
preferably 1K to 3K, most preferred 1K to 2K, below the temperature
of the fluid coolant return flow and returning the fluid coolant to
the at least one first cooling circuit.
2. The method as claimed in claim 1, wherein the power density of
the IT equipment in the racks being at least 5 kW (electrical) per
rack, more preferred at least 8 kW (electrical) per rack, most
preferred at least 10 kW (electrical) per rack.
3. The method as claimed in claim 1, wherein the racks (202) being
arranged as two dimensional arranged data centres, where the racks
are located on one level, or as three dimensional arranged data
centres, where the racks (202) are located on more than one level
within the data centre.
4. The method as claimed in claim 1, wherein the power density of
the IT equipment (200) installed and operating within the racks
(202) creates a volumetric heat dissipation rate which corresponds
to least about 5 kW/m.sup.2, preferably to least about 10
kW/m.sup.2, most preferred to least about 20 kW/m.sup.2.
5. The method as claimed in claim 1, wherein the room temperature
of the space housing the multiplicity of racks (202) is about +2K,
preferably +1K, more preferably +0.5K, most preferred about the
same, of the temperature of the return flow of the fluid coolant of
the first cooling circuit.
6. The method as claimed in claim 1, wherein the source of coldness
provides the back cooling through (i) external cold water sources,
preferably ground or surface water, (ii) evaporation cooling which
operate based on the evaporation principle, including evaporation
cooling towers with or without open cooling towers, (iii) hybrid
cooler or (iv) dry cooler.
7. The method as claimed in claim 1, wherein the fluid coolant
entering the data centre for cooling via the at least one cooling
circuit has temperature at most 0.2K below the temperature of the
fluid coolant entering the heat exchanging means (206, 207).
8. The method as claimed in claim 1, wherein the temperature of the
return flow of the fluid coolant of the first cooling circuit being
at most 3K, preferably at most 2K, most preferred at most 1K, above
the temperature supplied by the source of coldness entering the
data centre for total power densities of up to 10 kW (electrical}
per rack or wherein the temperature of the return flow of the fluid
coolant of the first cooling circuit being at most 4K, preferably
at most 3K, above the temperature supplied by the source of
coldness entering the data centre for total power densities of at
least 10 kW (electrical) per rack.
9. The method as claimed in claim 1, wherein the method for
operating the data centre does not operate any additional air
conditioners.
10. The method as claimed in claim 1, wherein the method for
operating the data centre does not have any other active means, in
particular fans, for creating an air flow (205) in the rack towards
the heat exchanging means except for such active means being
present in the IT equipment located in the rack.
11. The method as claimed in claim 1, wherein the active means, in
particular fans, being present in the IT equipment (200) create an
air flow (205) in the rack towards the heat exchanging means which
corresponds to an air volume current of 100 to 600 m.sup.3/(h*kVV),
which corresponds to at least 0.5 m/s, preferably of at least 0.8
m/s, in particular of at least 1.1 m/s.
12. The method as claimed in claim 1, wherein the active means, in
particular fans, being present in the IT equipment (200) create an
air flow (205) in the rack towards the heat exchanging means which
create an air back pressure by the heat exchanger corresponding to
maximum 10 Pa for air flow rate corresponding of up to 0.5 m/s,
preferably maximum 16 Pa for air flow rate corresponding of up to
0.8 m/s, more preferred maximum 20 Pa for air flow rate
corresponding of up to 1.1 m/s.
13. The method as claimed in claim 1, wherein the pressure drop
across the heat exchanger is set below 22 kPa for a volume current
of 3 m.sup.3/h for fluid coolant, preferably water, preferably
below 54 kPa for 5 m.sup.3/h for fluid coolant, preferably water,
most preferred below 200 kPa for 10 m.sup.3/h for fluid coolant,
preferably water.
14. The method as claimed in claim 1, wherein the flow rate for the
fluid coolant, preferably water, is set from 0.9 m.sup.3 per hour
and per kW installed and operating for a difference of 1K and to
0.17 m.sup.3 per hour and per kW installed and operating for a
difference of 5K.
15. The method as claimed in claim 1, wherein the temperature of
the fluid coolant entering the heat exchanging means (206, 207) is
adjusted to 0.1 to 0.5K per kW installed and operating per Rack not
exceeding 10 kW per Rack, below the temperature of the fluid
coolant return flow exiting the heat exchanging means (206, 207) of
the racks (202) or wherein the temperature of the fluid coolant
entering the heat exchanging means (206, 207) is adjusted to 0.1 to
0.2K per kW installed and operating per Rack amounting between 10
kW and 25 kW per Rack, below the temperature of the fluid coolant
return flow exiting the heat exchanging means (206, 207) of the
racks (202), or wherein the temperature of the fluid coolant
entering the heat exchanging means (206, 207) is adjusted to 0.1 to
0.125K per kW installed and operating per Rack amounting to above
25 kW per Rack, below the temperature of the fluid coolant return
flow exiting the heat exchanging means (206, 207) of the racks
(202).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application is a continuation application of U.S.
patent application Ser. No. 14/398,758, filed Nov. 4, 2014 and
titled "Fluid-Cooled Data Centres Without Air Conditioning, and
Methods for Operating Same," which is a national stage application
(under 35 U.S.C. .sctn. 371) of PCT/EP2013/001391, filed May 10,
2013, which claims the benefit of European Application No.
12003748.6, filed May 11, 2012, and European Application No.
12007913.2, filed Nov. 23, 2012, each of which is incorporated
herein by reference in its entirety.
DETAILED DESCRIPTION
[0002] The present invention relates to a method for operating a
data centre, which is adapted to house a multiplicity/plurality of
racks being designed to provide storage space for IT equipment. The
data centre is equipped with cooling means in order to provide
dissipation of heat being generated by the IT equipment.
[0003] In the prior art, there exist various data building
structures for housing a multiplicity of racks, each of which
comprising storage space for IT equipment.
[0004] Conventional data centres most typically are buildings,
which comprise a false floor for a computer infrastructure, which
is typically housed in 19'' rack enclosures. In conventional data
centres, the cooling is still accomplished by cold air, which is
pumped into the false floors having holes at the appropriate
locations in front of the racks. In this way cold air is supplied
at the air intakes of the computer racks. This design typically
requires the concept of guided airflows, feeding cold air into the
racks and removing the heat from the IT equipment.
[0005] WO 2010/000440 discloses a typical state of the art
conventional data centre building in FIG. 1. This conventional
design is somehow disadvantageous, because the single racks have to
be designed as closed racks and the air flow through respective
racks has to be surveyed and controlled in order to avoid pumping
unnecessary amounts of cold air from the cold aisle. There exist
various concepts, providing a regulation of the air flow into the
cold aisle, such that the fans providing the air flow operate at
the lowest possible power. The hot air generated by equipment
inside the rack is fed back to heat exchangers being located
somewhere else in the data centre building. The heated air is
either cooled down again or fresh air is used in order to provide a
stream of cold air.
[0006] The prior art, such as WO 2010/000440, outlines the use of
water cooled racks for high density data centres. In the prior art
the heat of the electronic equipment is transferred to cooling
water by way of heat exchangers, as disclosed in WO 2010/000440, or
either mounted in the racks or in the aisles. Other prior art uses
direct cooling of the electronic equipment installed in the racks
with water.
[0007] Besides the typical state of the art conventional data
centre building, WO 2010/000440 discloses a new energy efficient
architecture for multi-storey computer data centre using liquid
cooling media for dissipation of heat being generated by the IT
equipment. The so called Green-IT concept realised by WO
2010/000440 allows the reduction of energy consumption for cooling.
Conventional data centres often require up to 50%, and even more,
of their energy consumption for cooling. The novel cooling concept
of WO 2010/000440 enables data centres which require less than 10%
(partial PUE<1.1) of their energy for cooling.
[0008] The stationary multi-storey computer data centre of WO
2010/000440 becomes a kind of benchmark for later Green-IT concepts
to follow as a constant development towards energy efficient data
centre.
[0009] However, stationary computer data centers as disclosed in WO
2010/000440 require a constant demand for such centres and
therefore are considered as long-time investments. In addition,
mobile data centres become more and more attractive, because such
mobile data centre container can easily be installed in the near
neighborhood and contain their own infrastructure so that they can
be "plugged-in" where stationary computer data centre are
undersized and/or only temporary needs exist.
[0010] The design of the data centres, whether they are mobile or
stationary is subject to constant improvement to optimise the costs
for cooling the IT equipment. Beside the design, the methods for
operating such data centre allow for further improvement to achieve
optimised energy consumption for cooling.
[0011] This invention is to provide such a method for operating a
stationary or mobile data centre unit.
[0012] Therefore, the instant invention relates to a method for
operating a data centre comprising: [0013] (i) a building for
housing a multiplicity of racks (202), each rack being an open rack
housing IT equipment, [0014] (ii) the racks (202) being an open
rack housing IT equipment (200) [0015] (iii) the racks (202)
comprise heat exchanging means (206, 207) being adapted to transfer
the heat generated by the IT equipment to a fluid coolant, said
heat exchanging means being an element of the racks or an element
attached to the racks, [0016] (iv) at least one first cooling
circuit (203, 204), said cooling circuit being a closed cooling
circuit, which is adapted to supply the heat exchanging means (206,
207) of the racks (202) with a fluid coolant and is further adapted
to convey the heated coolant away from the heat exchanging means
(206, 207) of the racks (202) through the reflux of the cooling
circuit, [0017] (v) said first cooling circuit (203, 204) being
connected to a source providing coldness, said source being located
outside the space housing the multiplicity of racks, [0018] (vi)
the IT equipment (200) located in the respective racks having
active means, preferably fans, for cooling parts of the IT
equipment, preferably the CPU and/or GPU and/or a storage hardware,
said active means creating an air flow (205) in the rack towards
the heat exchanging means (206, 207) being an element of the racks
or an element attached to the racks, [0019] (vii) said racks (202)
having no other active means, in particular fans, except for those
contained within the aforementioned IT equipment, for creating an
air flow in the rack towards the heat exchanging means being an
element of the racks or an element attached to the racks, [0020]
(viii) said building for housing the multiplicity of racks (202)
comprising no other active means, except for those contained within
the aforementioned IT equipment (200), for creating an guided air
flow, [0021] (ix) at least one electrical power input, [0022] (x)
at least one mean for distributing the electrical power from the
power input to the individual racks, allowing redundant power
supplies in every rack, comprising the measures [0023] (a)
providing a fluid coolant from the source providing coldness to the
heat exchanging means (206, 207) of the racks (202) within the
first cooling circuit, said fluid coolant input flow entering the
heat exchanging means (206, 207) having a temperature of 1K to 5K,
preferably 1K to 3K, more preferred 1K to 2K, below the temperature
of the fluid coolant return flow exiting the heat exchanging means
(206, 207) of the racks (202), [0024] (b) controlling the fluid
coolant flow within the first cooling circuit (205) which is
adapted to supply the heat exchanging means (206, 207) of the racks
(202) to maintain the temperature of fluid coolant entering the
heat exchanging means (206, 207) of the racks (202) (input flow)
having a temperature of 1K to 5K, preferably 1K to 3K, more
preferred 1K to 2K, below the temperature of the fluid coolant
return flow exiting the heat exchanging means (206, 207) of the
racks (202), [0025] (c) conveying the heated fluid coolant leaving
the heat exchanging means (206, 207) of the racks (202) (return
flow) to the source providing coldness, said source being located
outside the space housing the multiplicity of racks, to remove the
heat from the heated fluid coolant to a temperature of 1K to 5K,
preferably 1K to 3K, more preferred 1K to 2K, below the temperature
of the fluid coolant return flow and returning the fluid coolant to
the at least one first cooling circuit.
[0026] The present invention provides for a method for operating a
data centre, avoiding the necessity of guiding the cooling air
across all racks to create cold aisle within the data centre. The
only active means are typically fans contained within the
aforementioned IT equipment, which create an air flow (205) in the
individual rack towards the heat exchanging means of the respective
rack. These active means, such as built-in fans in the IT
equipment, typically do not exceed 10% of the electrical power of
the IT equipment installed and operating.
[0027] While still using the present invention one may use
non-substantive active means which do not contribute to the air
flow (205) in the rack, e.g. by installing fans other than those
contained within the aforementioned IT equipment. Such
non-substantive contribution of such additional non-substantive
active means provide at most 10% of the air flow (205) generated by
the active means contained within the aforementioned IT
equipment.
[0028] The present invention provides for a method for operating a
data centre containing racks housing IT equipment. Such IT
equipment includes all electronic equipment used in connection with
IT equipment, which generates heat during operation.
[0029] The present invention provides for a method in which at
least one cooling circuit is operated supplying a fluid coolant
into the data centre for cooling. In the present invention, the
temperature of the fluid coolant entering the data centre and the
temperature of the fluid coolant entering the heat exchanging means
(206, 207) is almost equal, which means that the temperature of the
fluid coolant entering the data centre is at most 0.2K below the
temperature of the fluid coolant entering the heat exchanging means
(206, 207).
[0030] In a preferred embodiment the present invention provides for
a method for operating a data centre in which the power density of
the IT equipment in the racks being at least 5 kW (electrical) per
rack, more preferred at least 8 kW (electrical) per rack, most
preferred at least 10 kW (electrical) per rack. The upper limit for
the power density per rack is mostly limited on the space available
inside the rack. Thus the upper limit is not limited per se and
typically can reach up to 1 kW or 1.5 kW per height unit in the
rack. For a typical rack the power density per rack amounts up to
42 kW (electrical) per 42 height unit rack.
[0031] The present method avoids the necessity of false floors used
in that context, too. In addition, the invention aims at optimizing
energy requirements and costs plus at arranging the computer racks
more densely in order to minimize the required length of the
network cables and to improve the system's communication
capabilities.
[0032] The present method for operating a data centre allows the
data centre to have a compact structure comprising larger, scalable
capacities and an increased volume density. The present method for
operating a data centre can be used for two dimensional arranged
data centres, where the racks are located on one level, or for
three dimensional arranged data centres, where the racks are
located on more than one level within the data centre.
[0033] The benefit of the present method for operating a data
centre increases with the power density of the IT equipment
installed within the racks. Such increased packing or storage
density for IT equipment, such as computer hardware, which provides
a heat dissipation, which can even exceed a volumetric heat
dissipation rate of 1 kW per m.sup.3 and more, preferably 1.5 kW
per m.sup.3 and more, more preferably 2 kW per m.sup.3 and more,
more preferably 3 kW per m.sup.3 and more, which cannot be achieved
using the conventional air cooling systems which are the state of
the art system nowadays. The aforementioned volumetric heat
dissipation rate is based on a data centre having 2.5 m ceiling
height and the net area used in the data centre. The net area of
the data centre is the area, which is occupied by the racks housing
the IT equipment, excluding any additional space for technical
building infrastructure, such as transformers, power generators,
battery rooms, fire extinguishing systems, storage area and the
like. In the preferred embodiment of the invention a rack is 120 cm
deep and 70 cm wide. The racks are mounted with a distance of 120
cm between rack rows. Therefore in the preferred embodiment of the
invention a rack consumes 1.7 m.sup.2 of floor space and 4.2
m.sup.3 of the net data centre area. Closer configurations, for
instance with 60 cm wide racks and smaller distances are
conceivable.
[0034] Thus the net area of the data centre used in connection with
the instant invention is the surface used to house the IT-equipment
racks. It is total surface of the data center minus the surface
used for technical infrastructure (power supply, cooling, UPS,
batteries, generators, fire management and other), for the access
infrastructure (non-secured and secured zones), preparation and
storage surface for IT-equipment as well as the IT-control rooms
and other surface needed for the management of the data center.
[0035] For practical reasons the volumetric heat dissipation rate
in conventional air cooling system, typically, does not exceed 6 kW
per Rack, which corresponds to about 2.5 to 3 kW/m.sup.2 and about
0.7 to 0.9 kW/m.sup.3 using the aforementioned assumptions.
[0036] All power densities per rack and other units derived
therefrom refer to the electrical power of the IT equipment
installed and operating in the respective rack.
[0037] As explained above, the benefit of the present method for
operating a data centre increases with the power density of the IT
equipment installed and operating within the racks. In particular,
for data centre having racks with installed and operating IT
equipment creating a volumetric heat dissipation rate which
corresponds to least about 5 kW/m.sup.2, preferably to least about
10 kW/m.sup.2, most preferred to least about 20 kW/m.sup.2, using
the aforementioned net area of the data centres/data centres room
housing the racks, an extremely efficient cooling is provided.
[0038] The present method for operating a data centre implements
open racks with passive heat exchangers, said heat exchanging means
being an element of the racks or an element attached to the racks,
which are built such, that most of the heated air, in the best mode
the entire heated air of the IT equipment installed inside the rack
is cooled back to the set room temperature. Preferably the heat
exchangers are located on the back side of the rack. The actual
position of the heat exchangers is determined by the direction of
the air flow (205) generated by the active means of the IT
equipment. In a preferred embodiment of the invention, the angle of
incidence of the air flow generated towards the surface of the heat
exchanger is at most 75.degree., more preferred at most 60.degree.,
more preferred at most 45.degree., more preferred at most
20.degree., most preferred between 0.degree. and 20.degree..
[0039] The design of the passive heat exchanger being an element of
the racks or an element attached to the racks, preferably being
located at the back side, of the racks is also important because if
they produce a very high back pressure towards the natural airflow
the overall cooling efficiency is reduced. Avoiding such back
pressure inside the rack has manifold advantages. First
heterogeneous equipment can be mounted inside the rack because the
low back pressure cannot have a negative effect on the airflow of
other IT equipment. For instance a high power server, mounted below
a low power server will not push it's hot exhaust air back into the
low power server, provided there is little back pressure inside the
rack. A second advantage is that there are little requirements
towards the sealing of the cable feeds through the rack. Normal
cut-outs or cable openings require self-sealing inserts, such as
e.g. KoldLok.RTM. sealings. The use of such self-sealing inserts in
the instant invention is possible but not mandatory. Due to the
avoidance of state of the art air-cooling and that guided air flows
in the data centre are not required; the potential leakage rate of
hot air is very limited in the instant invention.
[0040] The room temperature of the space housing the multiplicity
of racks corresponds to the cold air exhaust of the passive heat
exchangers being an element of the racks or an element attached to
the racks and is therefore connected to the fluid coolant
temperature. Preferably, the room temperature of the space housing
the multiplicity of racks is about +2K, more preferably +1K, more
preferably +0.5K, most preferred about the same, of the temperature
of the return flow of the fluid coolant of the first cooling
circuit. The instant method providing highly efficient cooling of
the racks allows for higher room temperatures as there are no risks
of heat loops anywhere in the data centre. The only area of hot air
is inside the racks.
[0041] The back cooling can be realised via the aforementioned
source of coldness, including but not limited to, external cold
water sources, such as ground or surface water, evaporation cooling
which operates based on the evaporation principle, including
evaporation cooling towers with or without open cooling towers,
hybrid coolers, dry coolers and the like, and any other state of
the art cooling techniques, including compression chillers.
[0042] The highest cooling and cost efficiency is achieved by usage
of counter flow, indirect draft, wet cooling towers. The cooling
principle of such cooling towers uses the evaporation heat of water
by evaporating water. For instance to cool a 1 MW data centre about
up to 1.7 m.sup.3 of fluid coolant, such as water, are required for
evaporation per hour. The cooling tower is entirely passive except
a fan, which is typically operated only if the outside air
temperature exceeds 15.degree. C. The lowest temperature
achievable, using open wet coolers corresponds to the wet bulb
temperature. It is measured psychometrically by covering a
thermometer with wet cloth. The usage of evaporation coolers
ensures that the coldest water supply temperature is above the dew
point. Therefore there is no risk of condensation anywhere inside
the data centre. The water supplies do not have to be
insulated.
[0043] The operating method of the preferred embodiment of this
invention uses water as cold fluid coolant, in which the fluid
coolant entering the data centre for cooling via the at least one
cooling circuit has temperature almost equal to the temperature
entering the heat exchanging means (206, 207). In this context,
almost equal means that the temperature of the fluid coolant
entering the data centre is at most 0.2K below the temperature of
the fluid coolant entering the heat exchanging means (206,
207).
[0044] In a preferred embodiment, the instant method operates with
a temperature of the return flow of the fluid coolant of the first
cooling circuit being dependent on the particular power density
installed and operating in the racks. For power densities of up to
10 kW (electrical) per rack, the temperature of the return flow of
the fluid coolant of the first cooling circuit being at most 3K,
preferably at most 2K, most preferred at most 1K, above the
temperature supplied by the source of coldness entering the data
centre and for power densities of at least 10 kW (electrical) per
rack, the return flow of the fluid coolant of the first cooling
circuit being at most 4K, preferably at most 3K, above the
temperature supplied by the source of coldness.
[0045] The aforementioned temperature difference between the return
flow of the fluid coolant of the first cooling circuit and the
fluid coolant input flow can also be higher for reduced fluid
coolant flow rates. Thereby the power demand by the required pumps
operating the cooling circuit is reduced during colder seasons or
periods of colder outside temperatures, typically at outside
temperatures below 17.degree. C., when the back cooling
system/source of coldness produces/provides sufficient low
temperature/cold fluid coolant at no extra costs.
[0046] Typically the racks used in the instant method are common
19'' rack enclosures. In a preferred embodiment, the racks are tall
racks which are particularly space-saving. The racks are placed on
the floor of the building and not necessarily on false floor
systems. Pipes and/or cable trays are mounted above the racks. In
case of an existing false floor for the retrofit of an existing
data centre such false floor can be equally used to conduct the
pipes. The heat exchanger doors can be connected to the cooling
circuit from below and above. In a further preferred embodiment
such as the data centre being a mobile data centre, the racks are
connected to the surrounding enclosure via shock-absorbing means,
thus protecting the racks and any associated/connected means, like
heat exchanging means and cooling pipes, against vibration and
shocks during transportation and assembly.
[0047] The term "open" in connection with the present racks means
that the front of the racks is open and allows the IT equipment
inside the rack to intake room air without flow resistance. It is
also possible to have an open front door, e.g. a lattice door,
which allows air to flow through without substantial flow
resistance. Such lattice door is the preferred embodiment as it
allows the measurement of the temperature of the air-intake. In
this preferred embodiment, two measurements are carried out,
typically one at one third height of the lattice door, and the
second at about two thirds height of the lattice door. The open
rack concept operated in the instant method allows intake of room
air and exhausting of such air taking up the heat generated by the
IT equipment. In a preferred embodiment, the air entering the open
rack and the air exiting the IT equipment towards the heat
exchanging means (206, 207) are separated by decoupling means
inside the rack, separating the air exiting the IT equipment
towards the heat exchanging means (206, 207) from the air entering
the open rack to ensure that no heated air is soaked into the IT
equipment.
[0048] Another advantage of the rack-based heat exchanging means is
that the racks themselves do not have to be kept closed and that
the air flow into and out of the racks does no longer have to be
controlled. As a further benefit, inside the data centre, there are
no additional air conditioners required, as the cooling function
may be completely taken over by the heat exchanging units of the
racks.
[0049] The racks used in the present invention do not have any
other active means, in particular fans, for creating an air flow in
the rack towards the heat exchanging means being an element of the
racks or an element attached to the racks. Only the IT equipment
located in the respective racks having active means, preferably
fans, for cooling parts of the IT equipment, preferably the CPU
and/or GPU and/or a storage hardware, and only said active means
cooling parts of the IT equipment creating an air flow in the rack
towards the heat exchanging means being an element of the racks or
an element attached to the racks.
[0050] The instant method for operating a data centre does not
require data centre having false floor and cold aisles arrangements
or design.
[0051] Most preferred are passive heat exchangers having a depth of
about 50 to 120 mm which can cause only a very low air back
pressure. Therefore hot air leaving the IT equipment in the racks
can pass the heat exchanger all by itself.
[0052] As already mentioned, the power density in modern computers
has reached 1 kW and even more per height unit installed in a rack.
The active cooling means of the IT equipment installed in a rack,
such as the fans for cooling parts of the IT equipment, preferably
the CPU and/or GPU and/or a storage hardware, create appropriate
air flow rates to remove the entire heat from the IT equipment. The
air flow rate depends on the temperature difference .DELTA.T
between the air entering the rack and the air leaving the IT
equipment. Typical temperature differences are .DELTA.T=5 to 30 K.
This temperature difference requires an air volume current of 100
to 600 m.sup.3/(h*kW), which corresponds to at least 0.5 m/s,
preferably of at least 0.8 m/s, in particular of at least 1.1
m/s.
[0053] State of the art IT equipment is designed to operate at a
temperature difference between cold and hot air around 10 K.
Therefore, the air flow rate inside a 42 height unit 19-inch rack
is a linear function of the power generated by the electronic
equipment and the average air temperature difference generated by
the equipment. Hence, operating with the 10 K difference and having
IT equipment installed corresponding to 20 kW electrical power, an
air volumetric current of 6000 m3/h which corresponds to an air
flow rate of 2.1 m/s for such 42 height unit 19-inch rack is
suitable. Such air flow rate in the instant method is solely
created by the active cooling means of the IT equipment per height
unit installed in a rack, such as the fans for cooling parts of the
IT equipment, preferably the CPU and/or GPU and/or a storage
hardware.
[0054] The instant method for operating a data centre allows the
transfer of the heat generated by the IT equipment installed inside
the rack to the fluid coolant without any additional active
elements.
[0055] In case the racks are not fully equipped with IT equipment,
it is beneficial to close large open slots, e.g. being greater than
3 height units, inside the rack in order to avoid hot air leaving
the rack towards its front side. Small openings for cabling do not
present a problem due to the low pressure inside the rack.
[0056] The instant method for operating a data centre preferably
allows efficient cooling of a data centre in which the power
density of the IT equipment in the racks being at least 5 kW
(electrical) per rack, more preferred at least 8 kW (electrical)
per rack, most preferred at least 10 kW (electrical) per rack. The
upper limit for the power density per rack is mostly limited on the
storage space available. Thus the upper limit reaches typically 1
kW per height unit in the rack, thus typically amounting up to 42
kW (electrical) per rack.
[0057] The racks used in the instant invention typically have
dimensions of 1.2 m.times.0.7 m.times.2 m and are preferably
arranged front to back for highest efficiency and back to back for
highest redundancy.
[0058] While most IT equipment, such as servers, implement a
front-to-back airflow there are exceptions to this rule. For
instance Cisco Nexus switch series receive cold air at the front
and the right side of the chassis while hot air is exhausted at the
left and the back side of the system. These switches do require 1 m
wide racks also. In the preferred embodiment of this invention such
airflow requirements are accommodated by use of 1 m wide racks,
which seal the left front and right back of the rack. Similar
configurations are conceivable for IT equipment using their chassis
sides for air intake. The side openings of the racks do not have to
cover the full height of the rack. Special switch compartments are
conceivable.
[0059] Also horizontal airflow separations at the back of the rack
are conceivable, for instance in order to allow very specific
determination of sources of potential smoke and for selectively
switching off the appropriate servers.
[0060] Many passive sheet metal air guides are conceivable in the
preferred embodiment of the invention in order to guide cold or hot
air and to potentially separate regions inside the rack. Such air
guides are entirely passive and do not adversely affect the cooling
efficiency of the system. It should be noted that such air guides
are generally not required in the preferred embodiment of the
invention and are merely used to fit existing devices into the
racks.
[0061] The present method for operating a data centre implements
open racks with passive heat exchangers being an element of the
racks or an element attached to the racks, preferably as back
doors, which are built such, that most of the heated air, in the
best mode the entire heated air of the IT equipment installed
inside the rack is cooled back to the set room temperature.
[0062] The individual passive heat exchanger being an element of
the racks or an element attached to the racks, and preferably is
located at the back of the individual rack and capable of
transferring the entire heat generated by the IT equipment
installed and operating within the rack to the fluid coolant.
[0063] According to a preferred embodiment of the invention, the
capacity of the heat exchangers is given by the nature of the fluid
coolant, the coolant input flow and the temperature difference of
the coolant input flow and coolant output flow. In the instant
method, the cooling capacity of the sum of all heat exchanging
means installed corresponds to the heat generated by the IT
equipment installed and operating in the data centre. Thus, the
instant invention ensures that no or no substantial amount of heat
generated by the IT equipment is released to the space housing the
multiplicity of racks, typically referred to as the data
centre.
[0064] The instant invention allows for operating a data centre in
which the air entering the racks, typically from the front side,
and the air leaving the racks, typically at the back side through
the heat exchanging means, have the same or essentially the same
temperature and substantially all the heat generated is removed by
the heat exchanger and the fluid coolant. Preferably, the
temperature of the air entering the racks and the temperature of
the air leaving the racks, typically at the back side through the
heat exchanging means, differ by less than +2K, more preferably +1
K, more preferably +0.5K, most preferred is about the same. Thus no
heat or no substantive heat is released to the space/building
housing the racks of the data centre.
[0065] As a result, the instant method providing highly efficient
cooling of the racks allows for higher room temperatures as there
are no risks of heat loops anywhere in the data centre. The only
area of hot air is inside the racks.
[0066] The instant invention allows that the heat exchanging means
directly receive the hot air generated by the IT equipment inside
the rack and transform this hot air back down to a desired room
temperature by simply conveying the heat to the fluid coolant
conveying piping. In this way, any routing of hot air or creating
any air flows inside the data centre can be avoided. By allowing
this, the distance over which hot or heated air travels can be
reduced to a minimum. It is only required to transport the heated
air inside the rack, in particular from the IT equipment to the
heat exchanging means. In this way, any difficult-to-control
turbulent air flow can be prevented. In addition, the instant
invention does not require the high throughput flow of cold air and
the problems relates with any condensation of moisture being
present in such air. Hence, the use of any air dehumidifiers
becomes superfluous.
[0067] According to another preferred embodiment of the invention,
the heat exchanging means do not comprise any active means, such as
fans, for guiding the heat/hot air from the IT equipment to the
surface of the heat exchanging means or through the heat exchanging
means. The relatively low and laminar stream of air obtained from
the CPU and/or GPU cooling fans inside the particular rack allow to
avoid additional fans and to avoid any additional fan power
consumption.
[0068] The present method for operating a data centre uses passive
heat exchangers having a low air backpressure. The air backpressure
generated by the heat exchanger depends on the air flow rate. The
heat exchangers used in connection with the instant method
preferably have an air backpressure of maximum 10 Pa for air flow
rate corresponding of up to 0.5 m/s, more preferred of maximum 16
Pa for air flow rate corresponding of up to 0.8 m/s, most preferred
of maximum 20 Pa for air flow rate corresponding of up to 1.1
m/s.
[0069] The aforementioned air flows and air back pressure work well
with the IT equipment installed in the racks, which typically
operate within the temperature difference between cold and hot air
being around 10K.
[0070] The instant method uses fluid coolant system. One major
concern in data centres it the potential of leaks, in particular
for water being used as fluid coolant.
[0071] The risk of water spills and the amount of damage caused by
spills corresponds to the pressure of the water system. Therefore,
a further aspect of the instant method is to use heat exchangers
having a low pressure drop across the heat exchanger.
[0072] The present method for operating a data centre uses passive
heat exchangers having a low pressure drop across the heat
exchanger.
[0073] The pressure drop across the heat exchanger depends on the
volumetric fluid flow of the fluid coolant. Therefore, in the
instant invention, the passive heat exchangers situated at the
backside of the racks provide preferably a pressure drop below 22
kPa for a volume current of 3 m.sup.3/h for water, preferably below
54 kPa for 5 m.sup.3/h for water, most preferred below 200 kPa for
10 m.sup.3/h for water.
[0074] Operating at a pumping rate below 5 m.sup.3/h for water, the
instant method can be accomplished below atmospheric pressure of
the fluid coolant being water.
[0075] The present method for operating a data centre requires
controlling the fluid coolant flow within the first cooling circuit
(205) which is adapted to supply the heat exchanging means (206,
207) of the racks (202) to maintain the temperature of fluid
coolant entering the heat exchanging means (206, 207) of the racks
(202) (input flow) having a temperature of 1K to 5K, preferably 1K
to 3K, most preferred 1K to 2K, below the temperature of the fluid
coolant return flow exiting the heat exchanging means (206, 207) of
the racks (202). Thus, the flow rate for the fluid coolant, such as
water, is preferably from 0.9 m.sup.3 per hour and per kW installed
and operating for a difference of 1K and to 0.17 m.sup.3 per hour
and per kW installed and operating for a difference of 5K.
[0076] One remaining concern was the potential power increase
caused by the servers' cooling fans due to the back pressure of the
heat exchanger. This was tested by opening and closing the back
door of the rack and determining the total power consumption of the
computers inside the rack. Both the total power consumption of all
servers in a rack and the supply current to one sample fan were
measured.
[0077] There was no significant difference in power consumption
measured when opening the back door, primarily due to the low back
pressure.
[0078] Preferably, each rack implements autonomous power
distribution units, supplying power to all electric components
inside the rack and monitoring the power consumption and electric
properties, in particular for high power densities, e.g. used in
scientific applications. This functionality is provided by an
embedded micro controller. It measures in addition air input and
output and cooling water temperatures. Further each rack implements
an independent smoke detector. In case of a smoke alarm or
overheating the servers are configured to automatically shut down.
After exceeding configured thresholds, the PDU will ultimately cut
the power. Such safety measures are important per rack because of
the high power density and corresponding fast temperature rise in
case of a cooling failure.
[0079] The heat exchanging means of the racks are connected to a
cooling circuit which supplies fluid coolant, preferably liquid
coolant, to each of the heat exchanging means through a piping
system.
[0080] In a preferred embodiment of the invention, the cooling
circuit comprises a piping system to remove the coolant. Usage of a
liquid coolant such as water and other suitable cooling fluids,
particularly with larger thermal capacities than air, is
advantageous due to numerous reasons. At first, the total heat
quantity that may be transferred and transported is, compared to
gaseous coolants, much larger. Secondly, it is possible to control
and monitor the flow and the transmission of the coolant more
easily, compared to a turbulent and laminar flow of a gaseous
coolant.
[0081] In another embodiment of the invention, the pressure of the
liquid coolant can be set up to below 2bar, so that in case of a
leakage minimal fluid ejection of the liquid occurs and the leakage
liquid flows along the cooling circuit. In such embodiment the
cooling circuit may have a hollow/sink to collect any such leakage
liquid preventing that any such leakage liquid comes into contact
with the computer hardware. The piping is arranged behind the
rack's back door, which presents a protection of the IT equipment
against water spills due to the fine granular heat exchanger
structure. In both cases any leakage in the piping system can be
detected by monitoring the pressure in the piping system and set an
alarm thus allowing to take appropriate measures against such
leakage, such as for instance the stopping of the pumps, in order
to reduce the pressure further and to stop the continued water
supply to the leak.
[0082] Further no insulation of the piping system is required as
the room temperature corresponds to the cold water return
temperature, which is significant higher than the dew point.
[0083] The data centre has at least one source providing coldness
being connected either directly or indirectly to the first cooling
circuit as mentioned before.
[0084] Most typically, the source providing coldness is at least
one cooling tower operating with counter flow, indirect draft, wet
cooling tower, in which water is sprayed from the top of a column
and cooled by evaporation of some of the water and thereby
collected downwards. In order to avoid contamination of the first
cooling circuit, the source providing coldness can be decoupled
from the source providing coldness by a second cooling circuit.
Such decoupling is typically achieved by redundant heat exchangers
which transfer heat from the first cooling circuit to the second
cooling circuit.
[0085] By way of this implementation any contamination of the
second cooling circuit being directly connected to the source of
coldness, which may be contaminated by air particles, such as
pollen, is separated from the first cooling circuit going inside
the data centre. The necessary pumps for pumping the fluid coolant
can be placed inside the data centre or outside the data
centre.
[0086] Depending on the environmental climate, in some geographical
areas common water chillers cause problems, e.g. during cold/freeze
periods. In such cases it is preferred to use so-called hybrid
cooling towers instead. Most typically such hybrid coolers are
plate heat exchanger through which the heated coolant is flowing
through and cooled by the environmental air. One example for a
hybrid cooler is shown in U.S. Pat. No. 7,864,530. To increase the
cooling capacity in summer, it is possible to spray water to the
surface of the plate heat exchanger and use the evaporation cooling
of such water. Since these hybrid cooling towers include a heat
exchanger no further heat exchangers are required. However, the
cooling water may require additives, such as glycol in order to
prevent it from freezing.
[0087] Further, the source providing coldness has means for
conveying the liquid coolant to the cooling circuit entrance. Such
means typically are pipes, preferably being flexible, made of
different materials, such as steel, stainless steel and/or
synthetic organic polymer materials.
[0088] In another embodiment of the instant invention, the data
centre situated in a unit such as a container or the data centre is
built using racks being pre-installed in support frames, which
preferably are standard size frames. This allows for
pre-installation/pre-assembly when building data centres or for
mobile data centres. Preferably such standard size frames, units or
container having the typical standard size of a common ISO
container which can be transported, loaded and unloaded, stacked
and transported efficiently over long distances by ship, rail,
trucks, semi-trailer trucks or planes. Most preferred are 20-ft
(6.1 m), 40-ft (12.2 m), 45-ft (13.7 m), 48-ft (14.6 m), and 53-ft
(16.2 m) long units/containers. The width typically is 10 ft (3.0
m) to 8 ft (2.4 m) and the height typically is 9 ft 6 in (2.9
m).
[0089] The present method for operating a data centre provides a
fluid coolant from the source providing coldness to the heat
exchanging means (206, 207) of the racks (202) within the first
cooling circuit, said fluid coolant input flow having a temperature
of 1K to 5K, preferably 1K to 3K, most preferred 1K to 2K, below
the temperature of the fluid coolant return flow exiting the heat
exchanging means (206, 207) of the racks (202).
[0090] Preferably, the temperature of the fluid coolant entering
the heat exchanging means is adjusted to 0.1 to 0.5K per kW
installed and operating per Rack not exceeding 10 kW per Rack,
below the temperature of the fluid coolant return flow exiting the
heat exchanging means (206, 207) of the racks (202).
[0091] Preferably, the temperature of the fluid coolant entering
the heat exchanging means is adjusted to 0.1 to 0.2K per kW
installed and operating per Rack amounting between 10 kW and 25 kW
per Rack, below the temperature of the fluid coolant return flow
exiting the heat exchanging means (206, 207) of the racks
(202).
[0092] Preferably, the temperature of the fluid coolant entering
the heat exchanging means is adjusted to 0.1 to 0.125K per kW
installed and operating per Rack amounting to above 25 kW per Rack,
below the temperature of the fluid coolant return flow exiting the
heat exchanging means (206, 207) of the racks (202).
[0093] The present method for operating a data centre allows for
efficient cooling of a data centres. For example, the coldest
temperature achievable with state of the art back cooling
technology using evaporation cooling is the wet bulb temperature,
which in Europe hardly reaches 22.degree. C. The appropriate wet
bulb temperatures are available at the local weather services.
Typically the fluid coolant, in particular the cold water, supply
is about 2 K warmer than the wet bulb temperature, which is the
theoretical limit. In the preferred embodiment of the invention the
heat exchanger adds another 2 K between the secondary and first
circuit. However, it should be noted that this temperature
difference is only a function of the size of the heat exchanger and
can be cost optimised. For example, a temperature difference of +1K
in the first cooling circuit (difference between heat exchanger
outlet and inlet), which would correspond for example to 9
m.sup.3/h water as fluid coolant and 10 kW electrical power of the
IT equipment installed and operating inside the racks, the lowest
fluid coolant, in particular cold water, return of the cooling
system is 5K above the wet bulb temperature. Allowing for another
+1K difference to the room temperature due to radiation of the warm
racks, warm air leaks the room temperature is 6K warmer than the
wet bulb temperature. This limit can be even reduced by increasing
the pumping rate, but at the cost of higher power requirement of
the pumps. However, taking into account that for instance in
Germany the wet bulb temperature exceeded 20.degree. C. during the
years 2007 through 2011 for about 140 hours on average. Therefore
only a small fraction of the time the pumps would have to operate
on high pumping rate and therefore will only generate a small
addition to the overall power budget. During cold outside
temperatures the cooling system is throttled in order to keep the
room temperature above 20.degree. C.
[0094] It should be noted that basically all commercial computer
systems and network components are rated to operate up to
35.degree. C. at nearly constant walk according to ASHRAE TC 9.9
(2011) and ETSI EN 300 019-1-3; V2.3.2. (2009-07). Many vendors
have announced to even increase this figure towards higher
temperatures because all cooling systems improve in efficiency with
increased room temperatures.
[0095] If the fluid coolant, in particular cold water, return
reaches 30.degree. C. it can be used to heat buildings if they
implement floor or wall heating without any heat pumps. The only
additional power required is the pump to move the water through the
heating manifolds inside the building and to potentially push it up
towards higher floors. In summer the floor heating can be connected
to the cold water supply and therefore be used for very efficient
cooling of the building, however at additional cooling requirements
for the cooling towers.
[0096] Most typically, most or even all racks are individually
connected to the cooling circuit, which provides an efficient
instrument for removing and discharging the heat from the computer
hardware.
[0097] Coupling each rack to be cooled to the cooling circuit
individually with the cooling circuit in connection with the
rack-specific heat exchangers suitable to remove the entire heat
generated by the computer hardware, provides the additional
advantage that it is possible to control and monitor the cooling
power and heat exchange individually and separately for each
individual rack within the structure of the data centre. Cooling
the hot air exclusively within the rack makes it possible to
install any rack package densities without requiring air flow
design, such as cold aisles or hot aisles.
[0098] The present instant invention allows using a so-called open
rack architecture ensuring the racks do not need to be hermetically
sealed anymore. Such open rack structure further allows easier
access to the IT equipment, in particular the computer hardware,
inside the rack, in case of any problems or maintenance needed. Due
to the low pressure of the air flow at the rear side of the IT
equipment normal openings for cabling can be easily closed.
[0099] Another preferred aspect of the present invention is that at
least some or all of the racks comprise control means. In this way,
the entire system may adaptively, locally react on local system
failures and may automatically initiate respective provisions in
order to compensate the failure.
[0100] According to another embodiment, the control means further
comprise temperature sensors, leak detectors for the piping and/or
the smoke detectors, whereby said detectors are coupled to an
emergency alarm system, which is adapted to selectively switch off
the hardware, rack and/or the relevant portion of the cooling pipe
unit.
[0101] The emergency system may be designed and arranged in any of
said racks individually and separated from an emergency system of
neighboring or adjacent racks. Smoke and leakage detectors may be
installed separately and independently from each other in order to
individually switch off burning or smoking IT equipment and to be
able to maintain all other operations of the data centre.
Alternatively, it may also be imaginable to use a combination of
individual detectors and/or to use a multi-functional detector.
[0102] According to a further embodiment, the racks further
comprise power scheduling means, that are adapted to keep an
overall rush-in electric current below a predefined threshold. This
embodiment is adapted to prevent, that the entire data centre draws
an amount of energy which cannot be provided by an external power
supply. Therefore, the power scheduling means are adapted to
regulate, that each rack or a pair/group of racks draws power from
an electric current- or voltage supply according to a given time
sheet.
[0103] For instance, a first rack may power-up after a given
time-delay compared to any other rack of the data centre. In this
way, peak-power consumption of the entire data centre can be kept
below a predefined threshold, thus ensuring, that the external
power supply does not break down. The power scheduling means may
either be implemented as a specific algorithm assigning a
predefined individual, hence different, time-delay to any of the
racks of the data centre building.
[0104] Alternatively, it is also conceivable, that a power
switch-on of the various racks is controlled by means of a
centralized architecture. However, also an interconnected emergency
system is in the scope of the present invention, whereby a
multiplicity of leak- and/or smoke detectors are electrically
coupled to a central emergency system, which may automatically
initiate respective provisions in order to counteract a system
failure.
[0105] According to another preferred embodiment, the data centre
further comprises at least one further cooling circuit, for example
a redundant first cooling circuit, comprising the same principal
structure than the first cooling circuit which takes over the duty
of the first cooling structure in case of any leakage or other
problem. Preferably, the cooling circuit, including the first
cooling circuit, has at least two fluid coolant intakes which
allows operation also in case of any leakage, partial
shut-down.
[0106] According to yet another preferred embodiment, all pumps in
the data center have a redundant backup pump, which can be
activated in case of the primary pump failing. Proper shut-off
valves allow the replacement of a broken pump while the system is
operating.
[0107] The instant method allows operating the data centre at
relatively high ambient temperatures, e.g. up to 30.degree. C.
[0108] The preferred embodiment of the invention implements an
additional redundancy if the racks are mounted back-back. In that
case the cold air of two rack rows is mixed in the aisle between
the racks. The two rack rows can easily be made independent by use
of independent pipes and pumps. In case of an entire rack row
failing due to a catastrophic leak or a failure of all redundant
pumps the air leaving the racks connected to the failing cooling
system will slowly rise until the servers exit air temperature is
reached, which is typically 10K higher than the ambient
temperature. For a rack with 10 kW power consumption the
temperature rise is about 3K per hour. The warm air leaving the
rack row with the failing cooling system is mixed with the air of
the opposite rack row. Therefore the air temperature inside the
aisle is on average only 5K warmer than the ambient temperature.
This temperature rise can be compensated by lowering the cold water
supply to the rack row with the working cooling system.
[0109] The power utility efficiency (PUE) used in connection with
the instant invention is defined in "Data Center Efficiency
Metrics--PUETM, Partial PUE, ERE, DCcE" (2011) by Dan Azevedo, Jud
Cooley, Michael Patterson and Mark Blackburn published on
www.thegreengrid.org. The by far largest contribution to the power
overhead of a data centre is the cooling. Additional contributions
are electric transformations and distributions, backup power
generation, such as battery backup systems, air conditioning and
the like. The presented invention allows reducing the cooling
overhead to a minimum. The instant method allows operating the data
centre at a power utility efficiency (PUE) of at most 1.3,
preferably at most 1.2, more preferred at most 1.15, in particular
at most 1.1
[0110] In the following, the invention will be described in detail
by making reference to the drawings in which:
[0111] FIG. 1 schematically illustrates a data centre operating
according to the instant method
[0112] FIG. 2 schematically illustrates a heat exchanging unit of a
data centre, according to an embodiment.
[0113] In the illustrated embodiment of FIG. 1, any of the racks
(202) comprises a separate heat exchanging unit (206), which is
equipped with a heat exchanger (207). The active means, such as the
CPU cooling fan, of the IT equipment (200) facilitates an air flow
(205) inside the rack (202) towards the heat exchanging unit (206).
The heat exchanging units (206) are all coupled to a piping
(203/204) conveying a liquid coolant, e.g. water, to any of the
racks (202).
[0114] The coolant supplied by means of a piping (203/204) is
beneficial in that the various racks (202) are entirely passive and
no longer have to be designed as closed racks. Moreover, heat
dissipation outside the various racks (202) can be effectively
reduced to a minimum or even completely avoided. Hence, it is no
longer necessary to control a global air stream inside the building
structure. In this way generation of hot spots which might be due
to some uncontrolled hot air flow outside the racks (202) can be
effectively eliminated.
[0115] Additionally, the airflow throughout the data centre
building structure does no longer have to be actively controlled,
since the ambient temperature around the racks (202) is kept on a
relatively cold level compared to the temperature inside the racks
(202).
[0116] In order to implement failure tolerance on the cooling
infrastructure, the racks (202) can be operated in an even/odd
fashion, where every second rack is coupled to the same piping,
namely either the first or second redundant first cooling circuit.
In this way, two redundant first cooling circuits can be maintained
providing a residual cooling capacity.
[0117] In case of a failure, for instance due to a leak in the
piping (203/204), a particular rack can be selectively decoupled
from the piping system (203/204).
[0118] Since there is no requirement to guide any air throughout
the data centre structure, such as the space housing the
multiplicity of racks, the IT equipment (200) containing racks
(202) can be placed in any arbitrary arrangement. A data centre
within the meaning of the instant invention contains more than one
rack (202).
[0119] Rising the ambient temperature in the data centre therefore
rises the fluid coolant, in particular cooling water, temperature,
which directly increases the cooling efficiency of the heated fluid
coolant, in particular the heated cooling water.
REFERENCE LIST OF REFERENCE NUMERALS
TABLE-US-00001 [0120] 200 IT equipment (having a power density 224)
201 grid floor 202 rack 203/204 piping system for first cooling
circuit 205 air flow inside the rack, solely created by active
means contained in the IT equipment 206 heat exchanging unit 207
heat exchanger 208 height units for IT equipment 210 IT equipment
fan 212 input air entering front side of racks (having room
temperature 222) 214 fluid coolant flowing through heat exchanging
units 214A input flow of fluid coolant (having an input coolant
temperature 218A and volumetric fluid flow 226) 214B output flow of
fluid coolant (having an output coolant temperature 218B and
volumetric fluid flow 226) 216 air back pressure of heat exchanging
unit 220 cold air exhaust temperature of air exiting heat
exchanging unit 230 coolant source 232 wet bulb temperature (in
proximity to the coolant source) 234 fluid pressure drop across a
heat exchanging unit
Example 1
[0121] A data centre, hosting a high performance computer consuming
500 kW of power and being installed in 34 racks each 19-inches and
having 42 height units. The racks are 1.2 m deep and 70 cm wide.
The rack floor space requires less than 100 m.sup.2 net area.
[0122] The cooling infrastructure mainly consists of two cooling
circuits, connected by a heat exchanger. The first cooling circuit
transfers the heat generated in the data centre's 19-inch racks to
a heat exchanger, which is cooled back by the secondary circuit.
The secondary cooling circuit uses two 313 kW counter flow,
indirect draft, wet cooling towers, where the makeup water is taken
from a neighbouring river. The entire cooling infrastructure is
mounted inside a 20 ft container with two cooling towers mounted on
the roof. Said towers can be maintained and cleaned one at a time
while the cooling system remains active but at reduced power. It
should be noted that this scheme requires a minimum of 50 kW
computer power in order to avoid freezing of the cooling systems
during winter. An emergency water draining infrastructure is
installed.
[0123] The entire cooling system implements three electrical
consumers: the secondary pump (6 kW), the first cooling circuit
pump (28 kW) and one fan in every cooling tower (4.5 kW each).
While the fan power can be throttled, as the fans are not required
at outside temperatures below 15.degree. C., the two water pumps
are configured to run at a constant, fixed volume current of 150
m.sup.3/h in the secondary and 220 m.sup.3/h in the first cooling
circuit. The water flow rate in the first cooling circuit is
sufficient to cool up to 900 kW power, while the secondary circuit
supports up to two times 313 kW to date. An upgrade of the system
to a total power of 900 kW is possible by adding one additional
cooling tower to the existing infrastructure. With the assumption
of a typical 35% average utilization of the cooling tower fans and
500 kW maximum HPC power, an average cooling overhead of 7.4% or
PUE=1.074 results. In case of the fully utilized cooling system
with a power load of 900 kW, the cooling overhead would be 4.9% or
PUE=1.049. Further optimizations are conceivable in particular in
case of the secondary pump. In case of this implementation the pump
has to drive the volume current over a large distance of 120 m
because the cooling container could not be placed close to the data
centre room.
Example 2
[0124] A mobile data centre container having 3 m width, 2.9 m
height and 12.2 m length is equipped with 13 19'' racks, each
having IT equipment which operates at 35 kW. The total power of 455
kW is cooled back by a hybrid cooler. The water pump requires 10 kW
and the hybrid cooler requires an additional 6 kW, which results in
a power utility efficiency of PUE=1.035.
* * * * *
References