U.S. patent application number 13/808310 was filed with the patent office on 2013-08-15 for system and method for cooling a computer system.
The applicant listed for this patent is Andreas Birkner, Peter Heiland. Invention is credited to Andreas Birkner, Peter Heiland.
Application Number | 20130205822 13/808310 |
Document ID | / |
Family ID | 43828284 |
Filed Date | 2013-08-15 |
United States Patent
Application |
20130205822 |
Kind Code |
A1 |
Heiland; Peter ; et
al. |
August 15, 2013 |
SYSTEM AND METHOD FOR COOLING A COMPUTER SYSTEM
Abstract
The invention relates to a system for cooling a computing
system, the computing system being cooled using at least two
cooling circuits.
Inventors: |
Heiland; Peter; (Raunheim,
DE) ; Birkner; Andreas; (Jena, DE) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Heiland; Peter
Birkner; Andreas |
Raunheim
Jena |
|
DE
DE |
|
|
Family ID: |
43828284 |
Appl. No.: |
13/808310 |
Filed: |
February 10, 2011 |
PCT Filed: |
February 10, 2011 |
PCT NO: |
PCT/EP11/00617 |
371 Date: |
April 1, 2013 |
Current U.S.
Class: |
62/259.2 |
Current CPC
Class: |
F25D 31/00 20130101;
G01M 3/04 20130101; H05K 7/2079 20130101; H05K 7/20836 20130101;
H05K 7/20827 20130101 |
Class at
Publication: |
62/259.2 |
International
Class: |
F25D 31/00 20060101
F25D031/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jul 6, 2010 |
DE |
10 2010 026 297.8 |
Claims
1. A system for cooling a computing system, comprising a
refrigeration machine, wherein the computing system comprises at
least a first and a second cooling circuit, and wherein said first
cooling circuit is operable using a liquid or via heat conduction,
and wherein at least said second cooling circuit is connected to a
cold section of the refrigeration machine.
2. The system for cooling a computing system as claimed in claim 1,
wherein a return flow of the first cooling circuit is connectable
both to a heat exchanger and to the cold section of the
refrigeration machine.
3. The system for cooling a computing system as claimed in claim 2,
wherein a return flow of the second cooling circuit is connectable
both to a heat exchanger and to the cold section of the
refrigeration machine.
4. The system for cooling a computing system as claimed in claim 1,
wherein the system comprises at least three cooling circuits, one
cooling circuit of which being operated by air and the two other
cooling circuits being operated using a liquid, wherein at least
one cooling circuit of the other cooling circuits being connectable
both to an external heat exchanger and to a cold section of the
refrigeration machine.
5. The system for cooling a computing system as claimed in claim 1,
wherein the first cooling circuit and the hot section of the
refrigeration machine each include a heat exchanger which are in
thermal communication with each other through a further heat
exchanger, and wherein waste heat from the two cooling circuits is
dischargeable collectively.
6. The system for cooling a computing system as claimed in claim 1,
wherein the refrigeration machine is a compression-type
refrigeration machine or a sorption refrigeration machine,
absorption refrigeration machine and/or a refrigeration machine
operating on the principle of absorptive dehumidification (DCS), a
refrigeration machine operating on the thermoelectric effect, or a
refrigeration machine operating on the magnetocaloric principle, or
a geothermal refrigeration machine, or a refrigeration machine
operating with Peltier elements, or a steam jet refrigeration
machine, or a refrigeration machine operating on the Joule-Thomson
effect, or a refrigeration machine operating on the principle of
evaporative cooling.
7. The system for cooling a computing system as claimed in claim 1,
wherein racks or processors or power components of the computing
system can be cooled using a liquid.
8. The system for cooling a computing system as claimed in claim 1,
wherein the system comprises means for selectively distributing the
cooling fluid within the computing system.
9. (canceled)
10. The system for cooling a computing system as claimed in claim
1, wherein the system comprises control electronics with an
interface for connecting the computing system.
11. The system for cooling a computing system as claimed in claim
1, wherein the system comprises a cooling module which accommodates
at least the refrigeration machine and an electronic
controller.
12. The system for cooling a computing system as claimed in claim
11, wherein the feed flow temperature of the first cooling circuit
differs by at least 20.degree. C. from the feed flow temperature of
the second cooling circuit.
13. The system for cooling a computing system as claimed in claim
11, wherein the first cooling circuit is coupled with processors or
power components of the computing system.
14. The system for cooling a computing system as claimed in claim
1, wherein a heat exchanger of the first cooling circuit or a heat
exchanger connected with a hot section of the refrigeration machine
is connected to the heating system of a building, to a hot water
supply, or a power generator.
15. The system for cooling a computing system as claimed in claim
1, wherein the refrigeration machine is integrated into a rack or a
server, in particular a blade server, or into other components
(power supplies, telecommunications), or is arranged directly
adjacent to a server or to a rack.
16. The system for cooling a computing system as claimed in claim
1, wherein a liquid of the second cooling circuit, after having
passed through a cold section of the refrigeration machine, can be
fed via a heat exchanger for cooling the air inside the computing
system, and wherein the liquid, after having passed through the
heat exchanger, can be fed into the first cooling circuit.
17. (canceled)
18. The system for cooling a computing system as claimed in claim
1, wherein the system comprises processor cooling means, and
wherein processors, RAMs, chip sets, memory devices, graphic
components, power components of power supplies, power components of
uninterruptible power supplies, power supplies, telecommunications
devices, or hard disks are connected to a processor cooling
circuit.
19. The system for cooling a computing system as claimed in claim
1, wherein the computing system and the refrigeration machine are
arranged in one room, wherein in particular the refrigeration
machine is integrated into a component of the computing system, or
is arranged adjacent to a component of the computing system, and
wherein there is no air conditioning provided to cool the air in
the room.
20. The system for cooling a computing system as claimed in claim
1, wherein the system comprises means for emergency shutdown in the
event of a loss of coolant.
21. The system for cooling a computing system as claimed in claim
1, wherein said means for emergency shutdown include means for
determining the severity or the location of the possible risk of
coolant loss, and wherein based thereon the measures of emergency
shutdown can be defined, in particular the emergency shutdown can
be limited to an affected section of the computing system.
22-23. (canceled)
24. The system for cooling a computing system as claimed in claim
1, wherein the system comprises a plurality of cooling circuits, of
which one cooling circuit is coolable without using the
refrigeration machine, and wherein another cooling circuit is
coolable using a refrigeration machine.
25. The system for cooling a computing system as claimed in claim
1, wherein the system comprises a plurality of cooling circuits, of
which at least two cooling circuits are in thermal communication
with each other and thus combined to form one circuit.
26. (canceled)
27. The system for cooling a computing system as claimed in claim
1, wherein the system comprises a plurality of cooling circuits,
wherein a bypass is provided in at least one cooling circuit, by
means of which the volume flow in the module to be cooled and
connected to the cooling circuit can be increased by a partial
recirculation of the coolant without increasing the total volume
flow of the coolant in the cooling circuit.
28-44. (canceled)
45. A computing system, comprising a housing in which components of
the computing system are arranged, wherein the computing system
comprises at least a first and a second cooling circuit, wherein
the first cooling circuit provides for cooling processors and power
components of the computing system using a liquid or by heat
conduction, and wherein the second cooling circuit comprises a heat
exchanger arranged in said housing.
46-57. (canceled)
58. A method for cooling a computing system, wherein the computing
system comprises at least a first and a second cooling circuit,
wherein the first cooling circuit is operated at a higher
temperature than the second cooling circuit and using a liquid or
by heat conduction, and wherein at least the second cooling circuit
is operated through a cold section of a refrigeration machine.
59-62. (canceled)
Description
FIELD OF THE INVENTION
[0001] The invention relates to a system and a method for cooling a
computing system, in particular for cooling a server farm.
BACKGROUND OF THE INVENTION
[0002] Computing systems, in particular server farms comprising a
large number of racks, generate large amounts of heat during
operation. For example, a server farm typically has a pure heat
output of several kilowatts. In order to discharge these large
amounts of heat, generally, air conditioners are used which are
very energy intensive in operation.
[0003] There are approaches known from practice which attempt to
use the waste heat of a computing system to heat a building.
However, often such an approach is not feasible for lack of
heatable building surfaces in the proximity, and depending on the
climate zone and season it is not suitable to provide for adequate
cooling of an existing computing system in an building. Moreover,
in the summer heating energy for heating buildings is often not
required.
[0004] It is estimated that the energy needed for server farms will
increase up to 100 GWh or more in the next few years, with up to
40% of this energy being attributed to cooling alone.
[0005] Conventional computing systems are usually cooled through
the air conditioning of the room, and the individual computers
release heat to the ambient air via a fan.
[0006] But there are also more recent approaches in which the racks
of a computing system are cooled using a liquid, wherein the
cooling air of the racks transfers its heat energy to a liquid to
be cooled outside the rack via a heat exchanger integrated in the
rack or arranged adjacent to the rack.
[0007] Another approach is to directly discharge the heat energy
from the processors using a liquid cooling circuit. A direct
discharge of heat energy is to be understood as a configuration in
which liquid-cooled heat sinks are in direct contact with the
processors. This method, though it has the advantage that a
majority of the generated heat can be discharged from a small local
volume, has not yet been implemented in practice, at least not on
an industrial scale, possibly due to the fact that the technical
difficulties associated with liquid cooling of processors, such as
adequately ensuring tightness, are still in no reasonable relation
to the benefits.
[0008] In view of the ever increasing computing power in less and
less space it can be assumed that the cooling load and associated
energy consumption will also increase.
OBJECT OF THE INVENTION
[0009] Therefore, an object of the invention is to reduce the
energy requirements of a conventional cooling system for computing
systems.
DESCRIPTION OF THE INVENTION
[0010] The object of the invention is already achieved by a system
for cooling a computing system, by a computing system, and by a
method for cooling a computing system according to any of the
independent claims.
[0011] The invention relates to a system for cooling a computing
system, which comprises a refrigeration machine. A refrigeration
machine commonly refers to a device which is used to produce cold,
i.e. a temperature that is lower than the ambient temperature.
[0012] The invention especially relates to compression-type
refrigeration machines, i.e. refrigeration machines having a
mechanical compressor by means of which the coolant is liquefied
and can subsequently evaporate in the cold section of the
refrigeration machine, whereby it cools down and produces the
cooling effect.
[0013] However, the invention also relates to any other types of
refrigeration machines, in particular sorption refrigeration
machines such as adsorption or absorption refrigeration machines,
in particular refrigeration machines operating on the principle of
absorptive dehumidification, also commonly referred to as a
desiccant cooling system (DCS), refrigeration machines operating on
the magnetocaloric effect, refrigeration machines operating with
Peltier elements, geothermal refrigeration machines, steam jet
refrigeration machines, refrigeration machines operating on the
Joule-Thomson effect, and/or refrigeration machines operating on
the principle of evaporative cooling.
[0014] According to the invention, the computing system comprises
at least a first and a second cooling circuit, wherein the first
cooling circuit is operable via a liquid and/or via heat
conduction. That means, the first cooling circuit is not an
air-based cooling system. Rather, the cooling effect is
accomplished using a liquid such as water, or by heat conduction
whereby the heat is directly discharged from the heat-generating
components via components having a good thermal conductivity. Heat
conduction also refers to the use of heat pipes which remove the
heat more quickly due to a condensation and evaporation process.
Further, according to the invention, at least the second cooling
circuit which usually is an air-based cooling circuit, is connected
to a cold section of the refrigeration machine.
[0015] The invention in particular suggests to cool components
which are operated at high temperature, in particular the
processor, using a liquid-based or heat conduction based cooling
circuit. Due to the high temperatures, in particular a temperature
above 50.degree. C., at which these components can be operated, it
is often possible to discharge the produced heat to the outside
without the use of a refrigeration machine, or to further use it as
useful heat for heating purposes and hot water preparation.
[0016] The processor cooling circuit in the sense of the invention
may not only include the main processors of the computing system,
rather the processor cooling circuit may also include additional
processors and electronic devices such as memory circuits, hard
disks, chip sets, power components of the power supply, which in
turn are included in different components of the computing system
such as in server racks, telecommunications equipment, power
supplies, data storages, and other components of the computing
system.
[0017] Hence, the computing system in the sense of the invention
not only comprises the servers but also other power supply
components, especially power adaptors and emergency power supplies,
communication modules, data storages, etc.
[0018] The second cooling circuit which is typically configured as
an air-based cooling circuit and is connected to the cold section
of a refrigeration machine, now only needs to remove the energy
which cannot be discharged (or is not discharged) through the first
cooling circuit which is operated at a much higher temperature. The
second cooling circuit typically operates at a feed flow
temperature which does not substantially exceed 20.degree. C., in
particular at a maximum of 20.degree. C. Specifically, this cooling
circuit may be configured as a closed system to which the
components of the computing system are connected. Since, now, the
amount of heat to be dissipated over the comparatively
inefficiently operating refrigeration machine is low, the cooling
energy required for the system can be reduced considerably.
[0019] The invention thus relates to a system for cooling a
computing system having a plurality of cooling circuits, in
particular at least two cooling circuits, wherein by distributing
the total thermal energy to be discharged to a plurality of cooling
circuits a distribution is effected to different temperatures of
these individual cooling circuits, which permits, based on the
respective temperature of this thermal energy, to cool a fraction
or several fractions of the total thermal energy to be discharged
in a particularly efficient manner, or to supply it for a further
use.
[0020] In one embodiment of the invention, a return flow of the
first cooling circuit can be connected with both a heat exchanger
and the cold section of the refrigeration machine. For example, the
heat exchanger may be mounted to the outside of a building.
However, a heat exchanger in the sense of the invention also refers
to a reuse of the cooling fluid, for example for generating useful
heat. Due to the fact that the first cooling circuit, in particular
the processor cooling circuit, can be connected both to a heat
exchanger, in particular an outside heat exchanger, and to the cold
section of the refrigeration machine, it is possible to selectively
distribute the amount of heat which is to be discharged through the
refrigeration machine and which is to be discharged through the
heat exchanger, in particular via a directional valve. So in order
to cool the first cooling circuit the refrigeration machine has
only to be used if, for example due to an elevated outside
temperature, cooling via an externally arranged heat exchanger is
no longer possible. Thus, the energy-intensive use of the
refrigeration machine is reduced to a minimum, while the system
enables to provide reliable cooling even in case of very high
outside temperatures.
[0021] In one embodiment of the invention, the cooling fluid may be
passed through nearby heat exchangers which are connected to the
printed circuit boards and so cool the printed circuit boards
and/or the devices thermally coupled with the printed circuit
board. Also, the cooling fluid may be passed through the printed
circuit boards themselves.
[0022] One embodiment of the invention comprises at least three
cooling circuits, one cooling circuit thereof being operated by air
and the other two cooling circuits being operated by means of a
liquid or heat conduction, and at least one cooling circuit of the
other cooling circuits, i.e. the liquid-based cooling circuits, can
be connected both to an external heat exchanger and to a cold
section of the refrigeration machine. The so defined system
effectively operates as a three-stage system. Specifically, it is
intended to provide three cooling circuits with different feed flow
temperatures.
[0023] For example, the processors of the computing system may be
cooled by a first cooling circuit having the highest feed flow
temperature. This cooling circuit usually does not required the
support of a refrigeration machine, rather it is possible, at least
in temperate climates, to remove the heat to the outside via an
external heat exchanger. Alternatively, it is possible to use the
high temperature level for other purposes, for example to heat
buildings, or to produce hot water or electricity. It will be
understood that it may yet be useful to configure the system in
such a way that the fluid of this cooling circuit may likewise be
fed to the cold section of the refrigeration machine in order to
ensure reliable cooling even at extremely high outside
temperatures.
[0024] Another liquid-based cooling circuit is operated at a feed
flow temperature which is between the feed flow temperature of the
above mentioned cooling circuit and the feed flow temperature of a
further, in particular air-based, cooling circuit. Another group of
heat-generating components which are cooled using a lower feed flow
temperature than the components of the first cooling circuit can be
connected to this cooling circuit. These may be hard disks and
storage devices, for example.
[0025] This second cooling circuit whenever possible uses an
external heat exchanger so that the use of the refrigeration
machine can be dispensed with. So depending on the climate zone it
is possible, at least in the winter months, to operate even this
other cooling circuit without using a refrigeration machine. In
case of elevated outside temperatures, on the other hand, recourse
is made to the refrigeration machine by selectively distributing
the coolant.
[0026] Another cooling circuit is usually air-based and operates at
a lower feed flow temperature than the two abovementioned cooling
circuits. This cooling circuit for example cools the air in the
racks or even the air in the room in which the computing system is
installed. Since for this purpose, generally, temperatures of
20.degree. C. or below are needed, this generally requires the use
of a refrigeration machine. However, because of the heat discharge
over the two other cooling circuits it is possible to considerably
reduce the use of the refrigeration machine. It will be appreciated
that depending on the size and configuration of the system, more
other cooling circuits may be provided at intermediate temperatures
in order to optimize the system so that as much heat as possible
may be discharged without using refrigeration machines.
[0027] Furthermore, as suggested according to another embodiment of
the invention, the system may comprise means for selectively
distributing the cooling fluid within the computing system.
[0028] In particular, it is suggested to distribute the cooling
capacity within the computing system in function of the workload
thereof. According to one embodiment of the invention, the system
for cooling the computing system may be connected with the
computing system itself, to optimize the distribution of coolant.
It is conceivable, for example, that at least some individual
servers of the computing system report, via an interface, the
respective work load and/or the respective temperature to control
electronics of the cooling system, so that the cooling system is
controlled in function of the work load, in particular regarding
the local distribution of different processing powers or waste heat
generation within servers, racks, components of the computing
center and within the computing center itself.
[0029] One advantage of such a control system is, inter alia, that
additional cooling capacity is already requested at a very early
stage, namely immediately upon an increase of utilization of the
computing system. In this way, for example in cooling systems
including a cold storage, the required capacity of thermal storages
for storing cold may be reduced by having the refrigeration machine
already switched on as soon as a need for additional cooling energy
is foreseeable due to the utilization of the computing system (and
not only when the temperature in the computing system has already
risen) and thus reducing the time to be bridged by a cold storage
between the demand of cooling energy and provision thereof by the
refrigeration machine (the refrigeration machine usually requires a
few seconds or minutes from its activation to provide the cooling
energy). Smaller thermal buffers permit more compact
configurations, which may be of advantage especially in case of
cooling modules integrated in the computing system, e.g. in racks,
or connected to the racks.
[0030] Furthermore, it is conceivable in case of an increase of
computing power to increase the amount of coolant supplied and/or
to reduce the temperature thereof. In particular it is also
conceivable in case of increasing computing power to operate at
least one coolant circuit at a lower temperature.
[0031] Moreover, in contrast to simpler control systems which are
controlled for example based on the return flow temperature, it is
possible in case of a lower work load to operate the computing
system at a significantly reduced power without the risk that in
case of a sudden increase of the work load overheating of
individual components occurs due to the low cooling capacity
supplied.
[0032] A temperature monitoring program may be installed on the
individual computers to control the cooling system, which runs in
the background and reports increasing cooling requirements to the
controller of the cooling system. As an interface in the context of
the invention an already existing LAN port may be used, for
example.
[0033] Also conceivable is remote monitoring and/or control of the
cooling system via a network, in particular based on the
internet.
[0034] In one embodiment of the invention, both the first cooling
circuit and the hot section of the refrigeration machine each
include a heat exchanger, which heat exchangers are thermally
coupled via another heat exchanger, so that the waste heat from the
two cooling circuits may be discharged collectively. This
embodiment of the invention is based on the realization that the
hot section of a refrigeration machine, in particular a
compression-type refrigeration machine, through which generally the
heat extracted from the system is discharged to the outside, and a
processor cooling circuit may be operated at similar feed flow
temperatures. If now the two cooling circuits are coupled via heat
exchangers, the generated heat may be discharged to the outside
using a single heat exchanger. An advantage thereof is that only
one external port has to be provided. This is particularly
advantageous in conjunction with the modular configuration
described herein, or with the embodiment in which the refrigeration
machine is integrated in the server or directly connected to the
server.
[0035] In one embodiment of the invention, the system comprises at
least redundantly configured pumps for distributing the cooling
fluid and/or a redundantly configured refrigeration machine. At
least in larger server farms, even in case of a failure of
individual components of the cooling system permanent continued
supply of the cooling fluid has to be ensured for a long time, for
which purpose buffering storages are generally not sufficient.
[0036] For emergency cooling, an additional conventional
refrigeration compressor or a supply of cold tap water into the
system may be provided, for example.
[0037] Furthermore, the cooling circuits themselves may be
configured redundantly, so that for example in case of a loss of
coolant in a cooling circuit the heat may be removed via a cooling
circuit redundant thereto.
[0038] In one embodiment of the invention, the system may be
integrated into an existing air conditioning system of a building
and/or into a hot water supply system and/or into an electricity
supply system. For example, it is conceivable that the process heat
which results from a refrigeration machine is used at least partly
to heat the building and/or to provide hot water. It is also
conceivable to use the process heat to generate electricity, for
example using Peltier elements. The term process heat refers to any
kind of energy removed from the cooling system, also referred to as
recooling.
[0039] However, it is also conceivable, as suggested according to
another embodiment of the invention, to use a refrigeration machine
which is operated using heat as driving energy. This is in
particular the case with sorption refrigeration machines. In such
an embodiment of the invention it is possible to connect the first
cooling circuit which operates at a higher feed flow temperature to
the hot section of the refrigeration machine so as to provide
driving energy. The second cooling circuit may then be connected to
the cold section of the refrigeration machine to cool the air in
the servers, for example. Especially advantageously, the fluid
discharged from the hot section of the refrigeration machine is
passed through an external heat exchanger. This is because this
fluid usually still has a sufficiently high temperature so that
heat can be discharged externally to the outside without the use of
refrigeration machines (depending on the particular, for example
climate-related, outside temperatures).
[0040] In a preferred embodiment of the invention, the system has a
modular configuration and comprises at least one cooling module in
which at least the refrigeration machine and an electronic
controller are arranged. It is in particular suggested to provide a
module which comprises a housing with ports, and to which, in
addition to a power supply and optionally the connection of the
computing system via an interface, the feed and return conduits of
the cooling circuit of the computing system can be connected.
Furthermore, the module preferably comprises ports for an external
heat exchanger through which process heat from the refrigeration
machine is discharged.
[0041] The controller of the system for cooling a computing system
is also integrated in the module.
[0042] The modules are preferably sized according to the system
dimensions of components of the computing center, e.g. as a 19''
system for rack components.
[0043] Ports for electric power supply, for communications and/or
for cooling conduits are preferably configured so as to be
automatically connected when the module is inserted. In this way, a
faster installation is realized for maintenance and replacement
purposes.
[0044] Moreover, in a preferred embodiment of the invention, the
module has at least one independent emergency power supply which at
least ensures the operation of the pumps which supply the cooling
fluid to the computing system, even in the event of a power outage.
It is conceivable to additionally connect at least one control
electronics of the cooling system to the emergency power supply.
For simpler control is also possible to drive the pumps such that
they continue to run in case the control electronics is switched
off.
[0045] Alternatively, the emergency power supply of the cooling
system may be ensured by an emergency power supply of the computing
system, in particular by an uninterruptible power supply.
[0046] Computing systems generally have an uninterruptible power
supply. Such uninterruptible power supplies of computing systems
are usually also cooled. Therefore, it is intended to use the
cooling system also for the uninterruptible power supply. An
uninterruptible power supply generally comprises at least
accumulators which can bridge momentary interruptions of the mains
voltage. The uninterruptible power supply usually starts up within
a few milliseconds, so that even short term voltage disturbances
are compensated for.
[0047] A computing system usually also has telecommunications
devices, such as modules for connection to a telecommunications
network. It will be appreciated that the cooling system according
to the invention, if necessary, also ensures cooling of these
telecommunications modules.
[0048] In another embodiment of the invention, a liquid of the
second cooling circuit, after having passed through a cold section
of the refrigeration machine, may be fed through a heat exchanger
to cool the air prevailing in the computing system. That is, as
already described above, the second cooling circuit is air-based,
and the air is cooled down by a heat exchanger which is for example
integrated in a rack of the computing system.
[0049] In this embodiment of the invention, the liquid after having
passed through the heat exchanger is fed to the first cooling
circuit. Therefore, this is an embodiment in which the two cooling
circuits are connected in series, so that the cooling fluid first
supplies cold to the second cooling circuit which is operated at a
low feed flow temperature, and is then fed to the first cooling
circuit, in particular the processor cooling circuit, at a higher
temperature.
[0050] In one embodiment of the invention, the refrigeration
machine is integrated in a rack or in a server. This particularly
permits refrigeration machines to be accommodated in the system in
decentralized manner. Also, this may permit a server to cool
itself, for example. In this case each cooling circuit may be
optimized to the specific individual device. A port for a cooling
circuit in the sense of the invention refers to any type of
interface through which heat energy can be transferred.
[0051] In one embodiment of the invention, refrigeration machines
are provided integrated in or immediately adjacent to a server, the
refrigeration machines being configured as a module.
[0052] Preferably, each module comprises heat exchangers,
controllers, pumps, interfaces, and the refrigeration machine
itself. However, providing just the refrigeration machine as a
module is also conceivable.
[0053] It is also possible, as suggested according to another
embodiment of the invention, that the refrigeration machine
(preferably implemented as a module) is arranged immediately
adjacent to the server or rack. For example, the refrigeration
machine may be disposed above or below a server or rack. So no
additional footprint is required. It is also possible that the
cooling module is arranged laterally, also, one refrigeration
module may supply several components such as racks with cooling
energy.
[0054] As is known, heat exchangers and fans for generating an
internal air circulation for cooling a rack, for example, such as
those of a rack cooling system, may be arranged both within or
adjacent to a rack, for example. So in another embodiment of the
cooling module, an arrangement of the cooling module in such a unit
for internally cooling for example a rack is possible.
[0055] In one embodiment of the invention, the refrigeration
machine is integrated in a server, in particular a blade
server.
[0056] According to one embodiment, the refrigeration machine is
configured as a module that is insertable into a server, in
particular as a plug-in module. This embodiment of the invention
may be used for conventional blade servers, for example.
[0057] Integration into the server or the computing system, or an
arrangement directly adjacent thereto allows for short cable
lengths and transfer paths for the coolant (liquid, heat
conduction, air), thereby reducing thermal losses of the cold
transfer, furthermore reducing the energy required for the cold
transfer (e.g. the pump power), and hence increasing efficiency.
Furthermore, integration or adjacent arrangement of the cooling
modules allows a modular configuration of the computing center with
respect to the cooling system; the components (e.g. racks) each
comprise a separate cooling system tailored to the component. Thus,
the computing center can be extended without the need to extend a
central cooling system or to expand the cooling capacity thereof
(except for the discharge of process heat). Furthermore, a
computing center is conceivable that does not require a central
cooling system (except for the discharge of process heat). Another
advantage of integrated or adjacent cooling modules, depending on
the embodiment, is a reduction of external ports for the cooling
circuits when several cooling circuits are already combined in the
cooling modules. So, for example, only one fluid port is needed as
an external port to discharge process heat. Otherwise, all
components can be integrated in the server or the rack.
[0058] A system for cooling a computing system may be configured
such that non-adjacent and non-integrated cooling modules or
refrigeration machines and adjacent or integrated refrigeration
machines or cooling modules are used in an optimum combination in
terms of investment costs and operating costs.
[0059] In one embodiment of the invention, the system for cooling a
computing system comprises a system for detecting a loss of coolant
and for initiating an emergency shutdown in a loss of coolant
event, which may also be configured as a module.
[0060] In particular, the means for emergency shutdown are
configured as a power supply interrupter.
[0061] For example, in a liquid-based cooling system which is
preferably operated at a positive pressure for pressure detecting
purposes, it is conceivable to centrally detect based on the
pressure if a fluid leak exists.
[0062] Then, in the event of a drop of pressure, for example the
entire computing system or portions of the computing system and/or
the pumps for circulating the coolant may be switched off, so that
the components are disconnected from power. This ensures that at
worst components are damaged which come directly into contact with
the cooling water, and that other damage to components due to the
electric conductivity of the cooling water is avoided by
disconnecting the power supply of the components.
[0063] Furthermore, it is conceivable that the emergency shutdown
comprises a pump which in the event a loss of fluid is detected
generates a negative pressure in the coolant system. For example,
the pump may pump out the liquid into a designated reservoir or
into drains. Due to the resulting negative pressure no or only
little additional water will leak, so that the damage in the system
remains localized.
[0064] In another embodiment of the invention, means for emergency
shutdown are integrated in a rack of the computing system.
[0065] For example, each rack may comprise means for detecting a
loss of coolant, in particular a humidity sensor. In case of a
liquid leakage, the power supply of the rack is disconnected. It is
likewise possible to provide the rack with automatically closing
valves, so that it is separated from the coolant circuit. An
advantage of this embodiment of the invention is that in this way
not the entire computing system fails, and at the same time leakage
of larger amounts of fluid from a rack is prevented.
[0066] Furthermore, the module for detecting a loss of coolant may
be a component of a cooling module.
[0067] In one embodiment, the invention provides for a system for
cooling a computing system that comprises a plurality of cooling
circuits, wherein one cooling circuit is coolable without using the
refrigeration machine and another cooling circuit is coolable using
the refrigeration machine. In particular, it is suggested to
discharge the waste heat of a first cooling circuit having a higher
feed flow temperature and higher return temperature without the use
of a refrigeration machine by using the outside air for recooling,
or by using the heat as useful heat, for example for heating
purposes and for hot water supply.
[0068] Alternatively, or in combination therewith, at least two
cooling circuits are coupled thermally and so are combined to form
one cooling circuit.
[0069] In particular, it is suggested to connect at least two
cooling circuits with a lower and a higher feed flow temperature,
respectively, in series. So, for example, the return flow of a rack
cooling circuit may be used to cool power components and
processors.
[0070] In one embodiment of the invention, process heat is
dischargeable through the combined cooling circuit. In particular,
the return flow of the last cooling circuit which has the highest
temperature is supplied to a heat exchanger.
[0071] In one embodiment of the invention, the system for cooling a
computing system comprises a plurality of cooling circuits, wherein
at least in one cooling circuit a bypass is provided, by which the
volume flow in the module to be cooled and connected to the cooling
circuit may be increased by a partial recirculation of the coolant
without increasing the total volume flow of the coolant in the
cooling circuit. So it is possible to keep the total volume flow
substantially constant, and to direct a portion of the volume flow
to detour components to be cooled, via a bypass. If now additional
cooling is required, the flow rate in the bypass may be reduced,
whereby the flow rate along the components to be cooled
increases.
[0072] However, vice versa it is likewise possible to reduce the
volume flow in the module connected to the cooling circuit without
reducing the total volume flow in the cooling circuit.
[0073] In one embodiment of the invention, a liquid is used as the
coolant which has an electrical conductivity of less than
10*10.sup.-6 S/m. Specifically, pure water or a water-glycol
mixture may be used. In this way, electrical damage to the
components of the computing system and the risk of electric shock
to operating personnel are reduced.
[0074] In one embodiment of the invention, components of the
refrigeration machine, in particular a compressor, may be cooled
using at least one of the cooling circuits. Thus, the refrigeration
machine is integrated in simple manner into the cooling of the
system and is in particular cooled by a liquid.
[0075] In particular, by connecting the compressor or the motor of
the compressor to one of the liquid-based cooling circuits, the
waste heat of the compressor or of the compressor motor (motor
heat) may be further used for example as thermal energy (for
example for building heating or for generating electric energy).
Moreover, this may avoid the need for generating the cooling power
to cool the compressor of the refrigeration machine by the
refrigeration machine itself (or by another refrigeration machine),
by removing the motor heat via another cooling circuit which can be
cooled directly in the recooling without any other refrigeration
machine, for example because of its high temperature. In this way,
the energy required to cool the computing center is reduced.
[0076] In another preferred embodiment of the invention, a
refrigeration machine is used which comprises a compressor that has
a soft start circuit.
[0077] A soft start circuit reduces the inrush current and thus
reduces the torque of the motor in the start-up phase. In addition
to a softer start, the service life of the motor may be
significantly increased in this way.
[0078] The invention provides for a substantially thermally neutral
computing system which merely releases a heating power of less than
20%, preferably less than 10% of the power consumption of the
computing system as thermal energy into a room in which the
computing system is installed. Therefore, in many cases cooling of
the room by an energy-consuming refrigeration machine can be
dispensed with.
[0079] Thus, the computing system may possibly also be installed in
office areas, etc.
[0080] For reducing the heat transfer to the environment, a housing
of the computing system may be insulated, in particular the housing
walls may have a heat transfer coefficient of k<3 W/m.sup.2K,
preferably k<1 W/m.sup.2K.
[0081] For this purpose, the housing walls may comprise a thermally
insulating material, such as hard foam. It is also conceivable to
apply insulating material to the inner and/or outer surface of the
housing walls.
[0082] Furthermore, the housing walls of the computing system may
be coolable to approximately ambient temperature using fluid lines
which are connected to a cooling circuit. To this end, the walls
may be of a double-walled construction or may include cooling
coils. By cooling the walls, unwanted release of heat into the
environment can be prevented, even with a temperature in the
housing above room temperature.
[0083] The invention further relates to a computing system and in
particular to one embedded in a system as described above for
cooling a computing system. As far as details of the computing
system and cooling system thereof have been described above,
reference can be made to the corresponding features concerning the
computing system, without the computing system necessarily being a
part of the system described above.
[0084] The computing system comprises a housing in which the
components of the computing system, in particular processors,
memory, hard discs, etc. are arranged.
[0085] According to the invention, the computing system comprises
at least a first and a second cooling circuit, wherein the first
cooling circuit permits to cool processors and power components of
the computing system using a liquid and/or by heat conduction, and
wherein the second cooling circuit comprises a heat exchanger
arranged in the housing.
[0086] By the heat exchanger which in particular can be cooled by a
liquid, the inside of the housing is cooled by a cooling circuit,
and in this way thermal energy is discharged, which is not removed
through the first cooling circuit. The heat exchanger may for
example comprise a cooling coil arranged in the rack, or channels
in the housing.
[0087] Preferably, the computing system includes fluid ports for
both the first and the second cooling circuit.
[0088] While due to the high temperature the major part of the
thermal energy may be discharged through the first cooling circuit
by free cooling, it is also possible, other than with the system
for cooling a computing system described above, to dispense with
the use of a refrigeration machine for the remaining thermal energy
discharged through the second cooling circuit, and to also operate
this cooling circuit via free cooling.
[0089] In this way, the computing system may be configured to be
thermally neutral.
[0090] The housing is preferably formed as a rack.
[0091] The invention further relates to a cooling module, in
particular for a system for cooling a computing system as described
above.
[0092] The cooling module comprises a port for a first cooling
circuit, in particular a cooling circuit which permits to cool
processors and power components of a computing system using a
liquid. Moreover, the cooling module comprises another port for a
further cooling circuit. This further cooling circuit permits to
cool for example housings or servers of a computing system, at a
lower temperature. Furthermore, the cooling module comprises a port
for discharging process heat. Via this port recooling is
accomplished such that thermal energy is removed from the cooling
system.
[0093] In a preferred embodiment of the invention, the cooling
module comprises a refrigeration machine. The refrigeration machine
is in particular intended to provide a sufficiently low temperature
for the second cooling circuit which is operated with a lower feed
flow temperature.
[0094] In one embodiment of the invention, the cooling module is
configured as a plug-in module for a server, in particular a blade
server.
[0095] To this end, the cooling module includes mechanical means to
be inserted into a slot. The cooling module has a standard size
which occupies one or more slots of a server.
[0096] The invention further relates to a housing of a computing
system, which is in particular configured as a rack. The housing
includes a heat exchanger arranged in the housing, and a fluid port
connected to the heat exchanger. Also, the housing walls may be
formed as a heat exchanger.
[0097] The heat exchanger permits to cool the interior of the
housing.
[0098] Furthermore, the housing comprises another fluid port to
which modules, in particular plug-in modules or power components,
may be connected.
[0099] The invention further relates to a computing module, which
is configured as a plug-in module for a rack. A computing module
may comprise processors, for example, but also hard disks,
telecommunications electronics, etc.
[0100] According to the invention, the rack comprises a fluid port
through which processors and power components of the computing
module may be supplied with a cooling fluid.
[0101] The computing module may comprise a further fluid port for
supplying cooling fluid which in particular cools the housing of
the computing module, for example using an integrated heat
exchanger. However, it is also conceivable to accomplish cooling of
the housing merely based on air, so that the housing in which the
computing module is disposed is cooled down by a heat exchanger
arranged in the housing.
[0102] The invention further relates to a module for detecting a
leak, in particular for a system for cooling a computing system as
described above. The module comprises means for detecting a leak in
the cooling system, a controller, and means for shutting down a
computing system, at least partially.
[0103] Preferably, the module for detecting a leak is adapted to
determine the location or size of the leak based on measured
parameters such as the pressure in the fluid system, moisture
sensors, etc., and then selectively shuts down the computing system
or performs an emergency shutdown by interrupting the power supply,
in function of the location and severity.
[0104] The module for detecting a leak may be incorporated in
another component such as the cooling module described above.
Likewise, it is conceivable for the module itself to be configured
as a plug-in module for a server.
[0105] The invention further relates to a method for cooling a
computing system, in particular using a system for cooling a
computing system as described above.
[0106] The computing system comprises at least a first and a second
cooling circuit, wherein the first cooling circuit is operated at a
higher temperature than the second cooling circuit and by means of
a liquid and/or by heat conduction. Specifically, the feed flow
temperatures of the two cooling circuits differ by at least
20.degree. C., preferably by at least 30.degree. C.
[0107] Furthermore, at least the second cooling circuit is operated
through a cold section of a refrigeration machine.
[0108] The invention permits to reduce the cooling power generated
by the refrigeration machine to a minimum, since the first cooling
circuit which for example is configured as a processor cooling
circuit as defined above is operated at such a high feed flow
temperature that the heat can be removed without the use of a
refrigeration machine, at least for the majority of the time.
[0109] In one embodiment of the invention, the return flow of the
first cooling circuit is temporarily connected both to a heat
exchanger and to the cold section of the refrigeration machine, in
particular by means of a directional valve.
[0110] Therefore, waste heat from the first cooling circuit is only
fed to the refrigeration machine if an external discharge thereof,
for example via a heat exchanger, is not possible, for example due
to high ambient temperatures.
[0111] The first cooling circuit preferably provides for cooling
processors and/or power components of the computing system, whereas
the second cooling circuit preferably cools the racks of the
computing system and/or the room in which the latter is
arranged.
[0112] A heat exchanger also refers to providing the heat of the
hot section of the refrigeration machine and/or the heat of the
first cooling circuit for useful heat in particular for room
heating and/or water preparation.
DESCRIPTION OF THE DRAWINGS
[0113] FIG. 1 is a schematic view of a first embodiment of a system
1 for cooling a computing system.
[0114] Shown is a server with two cooling circuits.
[0115] The first cooling circuit is a liquid-based cooling circuit
and comprises a feed flow line 2 and a return flow line 3, through
which liquid-cooled components may be cooled, such as processors
and other power components.
[0116] Furthermore, the system 1 for cooling a computing system
comprises a second cooling circuit in form of an air cooling,
comprising a fluid inlet 4, and an outlet 5. This second cooling
circuit is coupled with a refrigeration machine (not shown).
[0117] The second cooling circuit serves to cool components 7 which
are not connected to the liquid-based cooling circuit.
[0118] The first cooling circuit is coupled to a heat exchanger,
via feed flow 2 and return flow 3, and the heat generated thereby
may be used as useful heat for the building. The first cooling
circuit may be operated at a higher temperature, for example the
target temperature may be 50.degree. C. at the feed flow and
60.degree. C. at the return flow. Due to the high possible feed
flow temperature, a refrigeration machine is not necessarily
required for cooling.
[0119] The second cooling circuit comprising the air cooling, by
contrast, is coupled with a refrigeration machine (not shown),
since it has to be operated with a lower temperature, for example
the temperature is not more than 20.degree. C. at the inlet and
35.degree. C. at the outlet.
[0120] However, since much of the energy to be discharged as heat
can be removed via the first liquid-based cooling circuit, there
are significant energy savings resulting in the system for cooling
a computing system.
[0121] The saved energy is calculated from the amount of energy
discharged via the first cooling circuit divided by the efficiency,
or coefficient of performance (COP), of the refrigeration
machine.
[0122] Since refrigeration machines usually work with poor
efficiency, energy savings are considerable.
[0123] Referring to FIG. 2, the principle of a refrigeration
machine will be explained schematically. The refrigeration machine
in this embodiment is a compression-type refrigeration machine.
[0124] Refrigeration machine 8 comprises a coolant circuit 13 which
may be considered as the refrigeration machine's internal coolant
circuit. The coolant in evaporator 9 expands, thereby becoming
gaseous and causing a temperature decrease. Evaporator 9 forms the
cold section of the refrigeration machine. Via a compressor 10, the
coolant is fed through the cooling circuit 13 to a condenser.
Through an increase of pressure the coolant liquefies and can
release waste heat at the condenser to extract energy from the
system. Condenser 11 forms the hot section of the refrigeration
machine 8. Via expansion valve 12, the coolant is again fed to the
evaporator, and thus a closed circuit is formed.
[0125] FIG. 2a schematically illustrates a refrigeration machine,
in which the internal coolant circuit 13 is connected, via an
internal heat exchanger 59, to coolant ports outside the
refrigeration machine.
[0126] FIGS. 2 and 2a thus illustrate the possibility of
configuring a cooling circuit according to the invention such that
it includes, instead of a cooling liquid (for example water), the
coolant of the refrigeration machine, wherein cooling is
accomplished directly through the evaporator of the refrigeration
machine. In this manner, the size of the refrigeration machine can
be reduced, which may be important in particular for refrigeration
machines integrated in servers, for example.
[0127] Referring to FIG. 3, the thermal connection of a
refrigeration machine will be explained. Refrigeration machine 8
comprises a cold section 16 having an inlet 14 and an outlet 15.
Cold section 16 for example cools the second cooling circuit of a
system for cooling a computing system.
[0128] Hot section 19, likewise, comprises an inlet 17 and an
outlet 18. The hot section, for example, may have a feed flow
temperature of 50.degree. C., whereas the return flow temperature
of the cold section is 15.degree. C., for example.
[0129] FIG. 4 schematically illustrates an exemplary embodiment of
a system 1 for cooling a computing system.
[0130] The system 1 for cooling a computing system comprises a
first cooling circuit 21.
[0131] The first cooling circuit is a liquid-based cooling circuit
which serves to cool processors and power components arranged in
rack 20.
[0132] Through the first cooling circuit 21, heat is fed to the
environment via heat exchanger 23. It will be understood that this
heat may be used as useful heat, or to generate electric
energy.
[0133] Furthermore, the system 1 for cooling a computing system
comprises a second cooling circuit 22. Second cooling circuit 22
comprises a heat exchanger 24 built into the rack 20 or connected
to the rack 20, which serves to cool the air in rack 20 and in a
rack-internal air circuit. Cooling circuit 22 is connected to a
refrigeration machine 8.
[0134] The feed flow temperature of cooling circuit 22 is
substantially lower than that of cooling circuit 21. Therefore, the
use of refrigeration machine 8 which is in particular configured as
a compression-type refrigeration machine is necessary, unless free
cooling can be used, as mentioned above.
[0135] Waste heat, also referred to as process heat, is discharged
to the outside by heat exchanger 25 through the hot section of
refrigeration machine 8.
[0136] FIG. 5 shows another embodiment of a system 1 for cooling a
computing system. Here too, the system comprises a first cooling
circuit 21, which is water-based.
[0137] In contrast to the exemplary embodiment illustrated in FIG.
4, the air directed through modules 26 of the server is cooled by a
heat exchanger 24 connected to the second cooling circuit 22 after
leaving the computing system. However, it is also possible to have
the air cooled before entering the computing system instead of
after leaving the computing system (not shown).
[0138] FIG. 6 shows another embodiment, in which in contrast to the
above embodiments the second heat exchanger 24 connected to the
cooling circuit is mounted apart from the rack of the computing
system. Using a fan 27 the air may be set in motion, and the second
cooling circuit may be implemented with a lower feed flow
temperature, for example using the air-conditioning of the room in
which the servers are installed.
[0139] FIG. 7 shows another embodiment of a system 1 for cooling a
computing system, which is based on the principle of the embodiment
illustrated in FIG. 4. Here, instead of external heat exchangers,
both the refrigeration machine is provided with a port 28 and the
first cooling circuit is provided with a port 29, through which the
heat may be removed and provided as useful heat, for example for
building heating, hot water supply, or for generating electric
energy.
[0140] FIG. 8 shows an exemplary embodiment of a system 1 for
cooling a computing system, in which a refrigeration machine can be
dispensed with.
[0141] A first cooling circuit 21 provides liquid-based cooling,
which cools the processors and power components of the computing
system 30.
[0142] Via port 29 the heat may be provided as useful heat (for
example for building heating, hot water supply, or for generating
electric energy), or may be discharged to the outside.
[0143] The second cooling circuit 22 comprises a heat exchanger 24
preferably arranged in the rack of computing system 30, by which
the air in the rack is cooled. Due to the small amount of heat to
be discharged, tap water may be used as a cooling medium, for
example. It will be understood that it is also conceivable, for
example, to preheat the tap water for hot water supply (for example
by heat exchangers--not shown), so that the energy extracted from
the second cooling circuit may be used, which only results in a
return flow temperature of for example below 30.degree. C.
[0144] FIG. 9 shows another embodiment of the invention, wherein
the second cooling circuit 22 is connected to the first cooling
circuit 21.
[0145] In this embodiment, the cooling fluid cooled by
refrigeration machine 8 is first supplied to heat exchanger 24
which cools the air in the rack.
[0146] The so already heated coolant fluid is then passed into the
first cooling circuit 21 and cools the processors and power
components.
[0147] In this manner, the cooling circuits are connected in
series, and the cooling liquid, for example provided by a
refrigeration machine, first passes through the cooling circuit
with the lower temperature level and then through the cooling
circuit with the higher temperature level. It will be appreciated
that more than two cooling circuits can be connected in series in
this way, for example the cooling circuits 21, 22, and 38 of server
37 shown in FIG. 13.
[0148] With reference to the drawings of FIGS. 10 to 12, different
ways of discharging the waste heat will be explained.
[0149] In the exemplary embodiment of a system 1 for cooling a
computing system shown in FIG. 10, the first cooling circuit 21 for
cooling the processors and power components is connected to an
external heat exchanger 23. The hot section of refrigeration
machine 8 is connected to another, separate heat exchanger 25
through which process heat is discharged.
[0150] FIG. 11 shows another exemplary embodiment, in which the hot
section of refrigeration machine 8 is connected to the first
cooling circuit 21. This is possible since for the processors it
suffice to provide a cooling fluid at a temperature of 50.degree.
C., for example.
[0151] The fluid extracted from the return flow of the first
cooling circuit 21 is first passed via a heat exchanger 25 and then
fed into the return flow of the warm section of refrigeration
machine 8.
[0152] This embodiment may also be referred to as a sequential
cooling circuit.
[0153] FIG. 12 shows another exemplary embodiment of a system for
cooling a computing system.
[0154] In this embodiment, an intermediate heat exchanger 31 is
provided. Coupled to heat exchanger 31 is both the first cooling
circuit 21 for cooling the processor as well as a cooling circuit
32 which forms the cooling circuit of the hot section of the
refrigeration machine. Heat exchanger 31 thermally combines these
cooling circuits and couples them to heat exchanger 25 arranged
outside.
[0155] An advantage of this embodiment of the invention is that
thus only two ports are required for connecting an external heat
exchanger 25. Because of a maximum temperature difference of
20.degree. C., preferably 10.degree. C., in the first cooling
circuit 21 and in cooling circuit 32 of the refrigeration machine
this is possible in a particularly simple manner.
[0156] With reference to FIGS. 13 to 15, a system 1 for cooling a
computing system with three cooling circuits will be described in
detail by way of a schematically illustrated exemplary
embodiment.
[0157] Referring to FIG. 13, the essential components of the system
1 for cooling a computing system are described.
[0158] The system 1 for cooling a computing system comprises a
first group of heat generating components 34 which are connected to
a first cooling circuit 21 which is liquid-based.
[0159] A second group of heat generating components 35 which is
likewise arranged in server 37 is also equipped with a liquid-based
cooling circuit. This additional cooling circuit will be referred
to as a third cooling circuit 38 below.
[0160] A third group of heat generating components 36 is formed by
heat generating components which are not connected to a
liquid-based cooling circuit.
[0161] These components 36 are cooled through air cooling by a
second cooling circuit 22 which comprises a heat exchanger arranged
in the rack.
[0162] Furthermore, a refrigeration machine 8 is provided having a
cold section 16 by which at least the second cooling circuit 22 is
cooled. The hot section of refrigeration machine 8 is connected to
an external heat exchanger.
[0163] Moreover, there is yet another external heat exchanger 23
provided, through which waste heat can be removed to the
outside.
[0164] Now, the sense of this system is that three cooling circuits
are provided that work with different feed flow temperatures. The
air-cooled components of the third group of heat generating
components 36 require the lowest feed flow temperature. The
processors and power components assigned to the first group of heat
generating components 34 are cooled with the highest feed flow
temperature, in particular with a feed flow temperature of about
50.degree. C.
[0165] Therefore, it is usually possible to largely or entirely
dispense with the use of a refrigeration machine, at least for the
first group of heat generating components 34, and to cool them
through external heat exchanger 23.
[0166] FIG. 13 illustrates a configuration in which the use of a
refrigeration machine is entirely dispensed with in the first group
of heat generating components 34.
[0167] The second group of heat generating components 35 is cooled
with a feed flow temperature which is between that of the first
cooling circuit 21 and that of the second cooling circuit 22.
[0168] Using valves 33, the cooling fluid of the third cooling
circuit 38 may now be selectively distributed to the heat exchanger
23 and the cold section 16 of refrigeration machine 8.
[0169] Depending on the cooling power required and the current
outside temperature, it is now possible to only have recourse to
the refrigeration machine 8 for cooling the third cooling circuit
38 if necessary, for example due to high outside temperatures.
[0170] It will be appreciated that, in similar manner, the first
cooling circuit may be distributed selectively to heat exchanger 23
and to the cold section of refrigeration machine 8 (not
illustrated), in function of the required cooling power and the
existing outside temperature.
[0171] Thus, FIG. 13 also illustrates that by means of valves and
pumps (not shown) at least two cooling circuits may be selectively
distributed to heat exchanger 23 and the cold section of
refrigeration machine 8.
[0172] FIG. 14 shows the system 1 for cooling a computing system as
illustrated in FIG. 13 in an operational state with an outside
temperature below 30.degree. C., for example below 30.degree. C.
and above 10.degree. C. The respective temperatures of the feed and
return flows are shown by way of example.
[0173] It can be seen that both the first cooling circuit 21 and
the third cooling circuit 38 are connected such, by means of the
valves, that these cooling circuits are connected to heat exchanger
23.
[0174] Therefore, only the second cooling circuit 22 has to be
supplied through the refrigeration machine 8.
[0175] FIG. 15 shows an operational state of the system 1 for
cooling a computing system with an outside temperature of above
30.degree. C., for example above 30.degree. C. and below 50.degree.
C. In this operational state, now, only the first cooling circuit
21 is connected to heat exchanger 23. Since the outside temperature
no longer suffice to bring the fluid of the third cooling circuit
38 to a sufficiently low temperature, now cooling circuit 38 is
also connected to the cold section of the refrigeration machine.
Thus, the refrigeration machine cools the third cooling circuit 38
and the second cooling circuit 22.
[0176] With reference to FIG. 16, the effect of the exemplary
embodiment described above for cooling a computing system will be
explained in more detail.
[0177] On top of FIG. 16, a curve is plotted which represents the
temperature in function of time. The time is represented on the
X-axis, and the temperature is represented on the Y-axis.
[0178] This could be both a temperature profile of a day as well as
a temperature profile of the average temperature in a year.
[0179] Below the temperature graph, it is indicated when the
refrigeration machine has to be used. Periods in which the
refrigeration machine has to be used are marked by vertical lines,
while periods during which cooling may be accomplished through an
external heat exchanger are indicated by oblique lines.
[0180] It can be seen that the first cooling circuit may be
operated without using the refrigeration machine for the entire
time.
[0181] In contrast, the second cooling circuit, i.e. the cooling
circuit of the three cooling circuits which is operated with the
lowest feed flow temperature, however, has to be operated using the
refrigeration machine for a considerable period of time; only at
night for example, and/or only in the winter the use of the
refrigeration machine may be dispensed with.
[0182] The additional third cooling circuit with a feed flow
temperature between the feed flow temperatures of the first and
second cooling circuits further improves the efficiency of the
system. This cooling circuit needs to be operated through the
refrigeration machine only at a temperature above 30.degree. C.
[0183] FIG. 13a shows, by way of example, a system for cooling a
computing system. Server 37 and the three cooling circuits 21, 22,
and 38 for the components 34, 36, and 35 of server 37 have been
described in conjunction with FIG. 13.
[0184] However, in contrast to FIG. 13, FIG. 13a shows a
configuration which includes free cooling, i.e. cooling without the
use of a refrigeration machine, which is illustrated and will now
be described schematically by way of example based on the specified
temperatures.
[0185] In this example, the three cooling circuits of the server
are connected in series, first cooling circuit 22 with a feed
temperature of 15.degree. C. and an outlet temperature of
20.degree. C. This cooling circuit 22 is connected to cooling
circuit 38, with a feed temperature of 20.degree. C. and an outlet
temperature of 40.degree. C. This cooling circuit 38 is in turn
connected to cooling circuit 21, with a feed temperature of
40.degree. C. and an outlet temperature of 60.degree. C. Thus, the
connection in series of these three circuits as a whole results in
a feed temperature of 15.degree. C. (inlet of circuit 22), and an
outlet temperature of 60.degree. C. (outlet of circuit 21). Heat
exchanger 25, in this example, provides an outlet temperature of
the cooling fluid of 20.degree. C. This cooling fluid is passed to
a heat exchanger 56 for free cooling and cools the outlet
temperature of the cooling fluid of cooling circuit 21 from
60.degree. C. to 60.degree. C.-.DELTA.T, before the latter is
passed to the inlet of the cold section 16 of refrigeration machine
8. Thus, the cooling power that has to be provided by refrigeration
machine 8 is reduced.
[0186] FIG. 17 shows an embodiment of the invention in which a
refrigeration machine 8, in particular a compression-type
refrigeration machine, is built into a rack 20 or arranged
immediately adjacent to the rack 20 (not shown). Refrigeration
machine 8 is connected to a heat exchanger 24 which forms the
second cooling circuit for cooling the air prevailing in the
rack.
[0187] Process heat is discharged through the hot section of
refrigeration machine 8 and by heat exchanger 25.
[0188] Processors and power components are connected with a first
cooling circuit 21, and the heat therefrom is discharged to the
outside through heat exchanger 23.
[0189] FIG. 18 shows another exemplary embodiment in which again
the refrigeration machine 8 is arranged in or on the rack.
[0190] Here, recourse is made to the sequential cooling described
above, in which the return flow of the hot section of refrigeration
machine 8 is coupled to the first cooling circuit 21.
[0191] That means, the cooling fluid is first passed from the
return flow of the hot section of refrigeration machine 8 via the
processors and power components.
[0192] Then, energy is extracted from the system using an external
heat exchanger 25, and the cooling fluid is returned to the hot
section of refrigeration machine 8.
[0193] FIG. 19 shows an overview of the components of a cooling
module.
[0194] In particular, the cooling system is configured modularly to
provide for a simple adaptation to the racks or other components of
the computing center.
[0195] The possible components of a cooling module are shown in the
organization chart illustrated in FIG. 19. A cooling module may
comprise a subset of the illustrated components. The components may
be configured as a cooling module, or non-modularly.
[0196] Especially the refrigeration machine is not forcibly a part
of the cooling module, it may be arranged outside the cooling
modules or only in one cooling module serving a plurality of racks,
the latter comprising another or each comprising another cooling
module including the other components.
[0197] The cooling system is in particular configured modularly in
order to provide for a simple adaptation to the racks or other
components of the computing center.
[0198] It is also possible that a cooling module comprises a subset
of the components shown. The components may be configured as a
cooling module, or non-modularly. Therefore, it will be understood
that the system may consist, as far as technically feasible, of any
combination of the following components.
Specifically, the individual components are defined as follows:
[0199] Refrigeration machine: Comprises a compression refrigeration
machine, or a sorption refrigeration machine, or a refrigeration
machine based on the magnetocaloric effect or on Peltier elements.
In order to achieve a high number of switching cycles (a high
number of switching cycles reduces the size of a cold storage
employed depending on the configuration of the cooling module)
without reducing the service life of the motors employed in
function of the type of refrigeration machine used, a soft start
circuit may be used for the compression refrigeration machine.
Furthermore, an electronic speed control may be used, which permits
analog control of the number of revolutions of the compressor motor
and thus of the amount of cooling energy provided via this
electronic speed control, instead of a digital on-off control of
the compressor motor, whereby the amount of cooling energy provided
is determined by the ratio of on-off cycles. [0200] Controller:
Comprises hardware and software. The controller serves to control
all components of the cooling module. Furthermore, the controller
serves to (or may serve to) control the temperatures of the cooling
circuits, for example, or to control the amount of cooling energy
provided by the compressor, or to control the amount of cooling
energy transferred in the individual cooling circuits. The amount
of cooling energy provided in the individual cooling circuits may
for example be controlled based on the temperature of the cooling
fluid (with the same volume flow, for example, more cooling energy
is transferred when lowering the outlet temperature of the cold
section of the refrigeration machine), or based on the volume flow
(with the same inlet and outlet temperatures of the cold section of
the refrigeration machine, more cooling energy is transferred when
increasing the volume flow of the cooling fluid). [0201] Cold
storage, reservoir: The cold storage is necessary, depending on the
embodiment, in order to bridge the time constant between turning on
the compressor and the provision of cooling energy, and in
particular in order to reduce temperature variations in the cooling
circuit. Moreover, the cold storage has an influence on the number
of switching cycles during operation if the cooling rate is
controlled through on-off cycles of the compressor, and therefore
on the service life of the refrigeration machine. The cold storage
is required only once per refrigeration machine. The cold storage
may be implemented as a sorption cold storage or as a latent cold
storage based on phase change materials, which is connected with
the cooling fluid via heat exchangers (not shown). Reservoirs are
necessary for filling the cooling circuits with liquid. [0202]
Interfaces: The cooling module or components of the cooling module
have disconnectable or pluggable interfaces for the communication
interfaces, the interfaces for connecting the cooling circuits
(coolants), and for the electrical interfaces. For example, the
cooling module or components thereof may be configured as a 19''
plug-in component, wherein the lines for communications, for the
cooling liquid, and the electrical terminals are connected
automatically upon insertion. Alternatively, it is possible to
implement these lines via quick release connections. In this way, a
modular and easy maintenance design is supported. [0203]
Communication interfaces: a communication interface, such as
Ethernet or LAN, connects the cooling module to the management of
the computing center, for example for reporting the operational
state of the cooling module or for coordinating measures in case of
a fault, e.g. a loss of coolant. Furthermore, the cooling module
may be connected with the cooling circuits (for example, with the
control of the rack cooling circuit), and with the components (for
example servers) for coordinating and optimizing the supply of
cooling energy. A user interface may indicate the operational state
to the personnel of the computing center, for example visually or
acoustically. [0204] Interfaces for cooling circuits: comprise the
connections between the cooling module or components thereof to the
cooling circuits according to the invention. The interfaces may be
configured as self-closing connections which prevent or at least
reduce leakage or dripping of the coolant fluid from open conduits.
[0205] Electrical interfaces: These interfaces comprise all
interfaces for power supply and to the pumps, valves, sensors and
other components belonging to the cooling system that are outside
of the cooling module. [0206] Mechanical interfaces: These
interfaces include shapes, dimensions and mounting elements of the
cooling module, which allow for a modular employment of the cooling
module or components thereof in the system for cooling a computing
system. For example, the cooling module or components thereof may
have a 19'' design, so that they may be attached in a rack,
similarly to servers or blade servers. Furthermore, the mechanical
interface may be designed such that the cooling module or
components thereof can be mounted adjacent to one or more racks,
while meeting the system dimension of the racks. [0207] Control of
the pumps/valves/sensors/actuators: These components include all
components for driving the pumps, valves, sensors, and actuators
(e.g. power electronics for controlling the pumps and valves,
electronics to read the temperature sensors), both for the cooling
circuits of the computing system and for the internal cooling
circuit of the cooling module, as described in FIG. 20. [0208]
Module for detecting a loss of coolant: This component is
illustrated in FIG. 37. [0209] Heat exchangers: These components
include the heat exchangers for recooling, for free cooling, and
for internal cooling. [0210] Casing: The casing ensures compliance
with the applicable safety regulations depending on the design of
the cooling module. Also, the casing prevents (or may prevent),
optionally by an additional thermal insulation, that waste heat of
the cooling module, for example from the compressor motor or from
power electronics, is released to the outside, rather it ensures
that the cooling module is thermally neutral to the outside. [0211]
Emergency power supply: In the event of a power failure, an
emergency power supply, such as one based on an accumulator
battery, can maintain the operation of the cooling module for some
time and thus reduce the risk of overheating of the computing
system due to a power failure. [0212] Moreover, a cooling module
may be provided with a means for removing condensate. In this way,
the condensate resulting at a cold spot of the cooling module
and/or of a heat exchanger of the computing system may be removed.
Depending on the amount, this may involve the evaporation of the
condensate, for example at the hot section of the refrigeration
machine, or a discharge of the liquid condensate. [0213] Heating:
In another embodiment, the cooling module comprises at least one
heating element for heating the computing system, for example using
a rack cooling circuit. This may be useful, for example, in order
to avoid an undesirably low temperature after a shutdown of
components or in case of a very low workload. In this way, the risk
of condensation in the racks or of such low temperatures for which
the components of the computing system are not adapted may be
reduced. Any cooling circuit may be used for heating purposes.
According to a further variation it is possible to utilize the
thermal energy of a cooling circuit to heat another cooling
circuit, for example the first cooling circuit for processor
cooling purposes may be connected to the second circuit for rack
cooling purposes, via a system of valves and/or pumps, such that
the first cooling circuit releases at least part of its thermal
energy into the second cooling circuit, at least at times. Thus,
less energy is needed for heating, furthermore, an additional,
usually electrical heating element may be dispensed with.
[0214] FIG. 20 shows an exemplary embodiment of a cooling module 39
which may for example be attached at or in a server or rack (not
shown).
[0215] Cooling module 39 comprises a housing 45 with a
refrigeration machine 8 and a controller 40 by which the cooling
module is controlled.
[0216] Furthermore, cooling module 39 comprises a port 43 for
processor cooling or for supplying a first cooling circuit.
[0217] Also, a port 44 is provided to which the rack cooling
circuit may be connected to provide a second cooling circuit.
[0218] As described in a previous embodiment, an intermediate heat
exchanger 31 is provided, which allows to combine process heat from
refrigeration machine 8 and heat from the first cooling circuit to
be discharged via port 41.
[0219] Cooling module 39 comprises an own internal heat exchanger
46 to cool the cooling module. The air flow 47 is indicated by
arrows. This cooling circuit cools the waste heat of the cooling
module itself. This waste heat is generated by the components of
the cooling module (for example by the motor of the compression
refrigeration machine, or by the controller). Due to the internal
cooling system of the cooling module, the cooling module is
thermally neutral to the outside.
[0220] The cooling module may likewise be cooled using existing
rack cooling means, for example an air circulation existing in the
rack.
[0221] Furthermore, the cooling module comprises leak detection
means 42 (a module for detecting a loss of coolant), as described
in FIG. 37, for example in form of a pressure monitoring device
and/or moisture sensor.
[0222] It will be understood that the cooling module 39 may
comprise additional components, such as electronic interfaces and
other cooling ports, mechanical connections, for example to be
inserted into a 19'' rack system, etc.
[0223] FIG. 20a shows an exemplary embodiment of a cooling module
39 which may be attached for example at or in a server or rack (not
shown). Here, in contrast to FIG. 20, the additional component for
free cooling is illustrated and will be explained with reference to
the temperatures indicated in the Figure.
[0224] Assuming a feed temperature at port 41 (recooling) of
<20.degree. C., for example, as illustrated, and a feed
temperature at port 44 (rack cooling) of 20.degree. C., for
example, the coolant may already be pre-cooled at the inlet of port
44, by heat exchanger 56, before being passed to refrigeration
machine 8. Therefore, the coolant does not has to be cooled from
20.degree. C. to 15.degree. C., i.e. by 5 K, by the refrigeration
machine, but by 5K-.DELTA.T. Thus, the cooling power to be provided
by the refrigeration machine is reduced, and accordingly the energy
consumption for cooling.
[0225] It will be understood that the principle of free cooling is
not only applicable in the cooling module, as illustrated, but in
the entire cooling system according to the invention. Moreover, the
principle of free cooling may be applied in combination with at
least two, preferably at least three cooling circuits, as
illustrated in FIG. 13a.
[0226] Referring now to FIG. 21, it will be explained how the
cooling module 39 is connected to a rack 20. The cooling module 39
is arranged close to the rack 20 or is integrated into the rack
20.
[0227] Via a first port (43 in FIG. 20) a first cooling circuit 21
is supplied, which serves for processor cooling purposes. This
cooling circuit is not connected to the cold section of the
refrigeration machine integrated in cooling module 39.
[0228] In order to cool the air inside rack 20, a further cooling
circuit 22 is provided, which is connected to the second port of
the cooling module (44 in FIG. 20).
[0229] Using this heat exchanger 24, the air within the rack is
cooled. Cooling circuit 22 is connected to the cold section of the
refrigeration machine integrated in the cooling module 39 (8 in
FIG. 20).
[0230] Due to the internal cooling of the rack, the rack may be
designed to be thermally neutral to the outside. Since the cooling
module is also thermally neutral to the outside, as described in
FIG. 20, the entire system consisting of the rack and the cooling
module is thermally neutral to the outside. Therefore, this system
does not require any additional cooling of the surrounding
room.
[0231] FIG. 21a shows a rack with a cooling module 39, as in FIG.
20, but with the difference that the heat exchanger and the fans
(not shown) for cooling the rack by means of heat exchanger 22 are
configured as a rack cooling module 61 arranged adjacent to the
rack, and that the air flow for cooling purposes is fed through
holes of the rack 20 and the rack cooling module 61. Rack 20, rack
cooling module 61, and cooling module 39 may be arranged one upon
the other, as illustrated, or side by side (not shown), or in a
combination thereof. Also, the cooling module 39 may be part of the
rack cooling module 61, or the rack cooling module 61 may be part
of the cooling module 39.
[0232] Referring to FIG. 22, the control of a cooling module will
be explained in detail. FIG. 22 shows a module which comprises a
subset of the components listed in FIG. 19.
[0233] The cooling module comprises a controller which is in
particular responsible for controlling the pumps and valves and for
controlling temperature and humidity sensors. Using this controller
and the appropriate pumps and valves, the coolant is controlled,
which for example flows to a heat exchanger or to a refrigeration
machine, etc. Therefore, the controller is connected with all
components which are supplied by the cooling module, for example
via a network connection.
[0234] Moreover, the controller is connected to a leak controller
including a moisture or pressure sensor, by means of which the
pumps and/or the voltage can be switched off, if necessary.
[0235] Furthermore, the cooling module is connected, via a network
connection, with the computing system and with the individual
sub-systems, such as individual racks, means for power supply and
telecommunications.
[0236] Referring to FIG. 23, the integration of a cooling module 39
in a computing system will be described in more detail.
[0237] In this embodiment, cooling module 39 is positioned above
the server 20 and is in thermal communication with the server 20,
as in FIG. 21.
[0238] The cooling module 39 comprises the refrigeration machine, a
controller, valves, pumps and sensors, a heat exchanger through
which the heat of a first cooling circuit and the process heat from
a refrigeration machine are combined and can be discharged through
port 41.
[0239] Furthermore, the cooling module comprises a leak controller
and an internal cooling circuit.
[0240] A particular advantage thereof is that with this modular
configuration only the process heat has to be discharged to the
outside via port 41.
[0241] Referring to FIG. 24, a system for cooling a computing
system that is integrated in a server 48 will be explained in
greater detail.
[0242] The system comprises a refrigeration machine 8 integrated in
the housing of server 48, in particular a compression-type
refrigeration machine.
[0243] The cold section of compression refrigeration machine 8
supplies a cold liquid to a heat exchanger 24 arranged in the
server, fans 50 generate an air flow in server 48, which is cooled
in heat exchanger 24. The temperature may be maintained at about
room temperature. Furthermore, instead of the fans, other means for
producing a fluid motion may be used, for example means based on
the principle of electro-hydrodynamics (not shown).
[0244] Through port 41 (feed and return flow), process heat of the
refrigeration machine 8 is discharged to the outside.
[0245] Furthermore, a first group of heat generating components 34
is coupled with a processor cooling circuit, via port 49 (feed and
return flow). Through this processor cooling circuit, a large part
of the energy is discharged without the use of refrigeration
machine 8.
[0246] Another group of heat generating components 36 is not
coupled to a processor cooling circuit but is cooled by the cold
air in the housing of server 48.
[0247] Referring to FIGS. 25 and 26, an exemplary embodiment will
be explained in which a cooling module is integrated in a blade
server.
[0248] FIG. 25 shows a blade server 51. Blade servers are also
known under the name BladeSystem or BladeCenter. The housing of the
blade server has a plurality of slots for modules 52, so-called
blades. These may be hard disks, memory chips, etc., for
example.
[0249] Cooling module 39 is configured in correspondence with the
modular configuration of the blade server and is likewise
plugged-in. In this exemplary embodiment, it occupies two slots of
the blade server.
[0250] FIG. 26 shows the rear side of the blade server.
[0251] A refrigeration machine 8 provides cold cooling fluid which
is supplied to an internal heat exchanger 24 to cool the interior
of the housing of blade server 51.
[0252] Process heat from the refrigeration machine may be removed
through the hot section and port 41.
[0253] Furthermore, modules 52 are provided with a processor
cooling circuit.
[0254] The fluid of the processor cooling circuit does not need to
be passed through refrigeration machine 8 but may be discharged
through port 44. It is also conceivable to direct the fluid through
the hot section of refrigeration machine 8, as with the
above-described sequential cooling, or to thermally combine the
processor cooling circuit with the discharge of process heat, by
means of an intermediate heat exchanger.
[0255] In this way only one port is needed for discharging the
process heat.
[0256] FIG. 27 illustrates such a system with a plurality of blade
servers 51.
[0257] The blade servers 51 comprise only one port for removing
process heat.
[0258] Otherwise, as illustrated herein by way of example, the
blade servers include, inter alia, a plugged-in cooling module as
illustrated in FIGS. 25 and 26, for example, and an internal second
air-based cooling circuit, as illustrated in FIG. 27a. Outside the
server, only one cooling circuit 53 is provided, through which heat
(process heat) is discharged to the outside, via heat exchanger
54.
[0259] FIG. 27a illustrates a second, air-based cooling circuit for
blade servers, in which the air flow 62 is directed through heat
exchanger 24. The blade server is designed such that this air flow
62 forms a closed air circulation within the blade server, so that
the blade server is or can be thermally neutral to the outside
(except for the liquid-based removal of the process heat).
[0260] Referring to FIGS. 28 through 34, the different ways to
integrate and arrange the cooling module, the computing system, and
the controller will be illustrated.
[0261] FIG. 28 shows an embodiment in which a respective cooling
module is disposed on top of each rack.
[0262] FIG. 29 shows an embodiment in which one cooling module is
arranged above two racks and therefore is responsible for cooling
both racks.
[0263] It will be understood that instead of the two racks a
plurality of further racks may be added.
[0264] FIG. 30 shows an arrangement with a respective cooling
module arranged below each rack.
[0265] FIG. 31 shows an arrangement with a cooling module at a
lateral side of a rack. It is in particular conceivable that this
cooling module supplies one or two racks with cold.
[0266] FIG. 32 shows an embodiment in which a cooling module is
integrated in the rack, for example as a plug-in module.
[0267] FIG. 33 shows an embodiment in which the controller of the
cooling module is arranged separately from the actual cooling
module. In this case, one controller is responsible for several
cooling modules. An advantage of this embodiment of the invention
is that the electronic control device has to be provided only
once.
[0268] FIG. 33a shows an embodiment similar to that illustrated in
FIG. 33, in which, however, the components of cooling modules are
distributed to a plurality of cooling modules. So it is possible
for example, that each rack of the computing center has for example
a first cooling module associated therewith, each of which for
example includes the refrigeration machine and other components of
the cooling module for cooling the cooling circuits of the rack,
while a second cooling module includes the heat exchanger for
recooling the process heat and combines the cooling circuits of
several racks in this heat exchanger.
[0269] FIG. 34 shows a configuration in which a complete cooling
module including a controller is integrated in each server or other
module of the rack.
[0270] As can be seen from the legend, a rack may also be
understood as another, similar component of the computing system,
for example a telecommunications device or a power supply
device.
[0271] A server may likewise be understood as another module such
as a hard disk module, etc.
[0272] Furthermore, components of the computing system as well as
components of the system for cooling a computing system according
to the invention may likewise be accommodated in a container (not
shown).
[0273] Referring to FIG. 35, another possibility of leak detection
will be discussed.
[0274] Shown is a fluid carrying conduit 54.
[0275] The fluid carrying conduit is surrounded by two electrodes
55, 56. If now water penetrates into the region between electrodes
55 and 56, both the capacity and the conductivity between the
electrodes changes.
[0276] Using an appropriate controller, a leak can be deduced from
the conductivity and/or from the capacity between the
electrodes.
[0277] A similar system may be configured as a sheet structure, as
shown in FIG. 36, where electrodes 55, 56 are spaced from each
other by means of a water permeable material, for example.
[0278] In this manner, the electrodes may be used as a part of the
housing or may be placed at the bottom of a rack or server, for
example.
[0279] Again, a leak may be deduced based on conductivity and/or
capacity.
[0280] Referring to FIG. 37, an embodiment of a module for
detecting a loss of coolant (leak detection) will be described.
[0281] This module comprises means for detecting a loss of coolant
and means for initiating an emergency stop.
[0282] As illustrated herein, the system may comprise a separate
controller which has communication interfaces, interfaces for
reading sensors, and for triggering actions as will be described
below.
[0283] A loss of coolant may be detected based on coolant pressure
monitoring (for example in a cooling system that is operated at a
positive pressure), or using sensors which can detect liquids
(capacitively or resistively, see FIG. 35 and FIG. 36), or based on
an unexpected increase in temperature in the components of the
computing system to be cooled (temperature monitoring at or in the
components to be cooled, such as processors), or based on the fact
that coolant pumps run at a higher speed due to a lack of medium to
be pumped, or using flow meters that monitor the amount of coolant
flowing therethrough.
[0284] An advantage of using sensors which operate independently of
the electrical conductivity of the coolant (for example, pressure
sensors) is that this permits to use coolants having a
comparatively low conductivity (for example below 2*10.sup.-8
S/m).
[0285] Preferably, a system including a plurality of means and
sensors as described above is distributed in and near the cooling
module, the servers, racks, other components of the computing
center such as power supplies, and connecting lines for the
coolant. In this way, in the event of a leak the location of the
leak can be determined.
[0286] The means of initiating an emergency shutdown may include a
communications interface through which components of the computing
center and/or responsible personnel is informed about a loss of
coolant. Furthermore, the means for emergency shutdown may in
particular comprise means for interrupting the power supply of the
concerned component (or components) of the computing center (e.g.
for the rack), and interfaces for controlling or shutting down
pumps and valves, by means of which the emergency shutdown as
described below may be effected.
[0287] Furthermore, using a leak controller and an associated
control system it is possible to determine which interventions must
be taken to protect the system (shutdown, partial shutdown,
controlled or immediate shutdown).
[0288] For this purpose, the leak controller is connected to a
switch of the main power supply for a server or a rack.
Furthermore, the controller has a communications interface in order
to generate a leak message, visually and acoustically, for example
on the computing system or on a higher-level control and monitoring
system of the computing center, and/or to control other modules, or
to co-ordinate a controlled shutdown.
[0289] Furthermore, the controller comprises a direct interface for
controlling pumps and valves.
[0290] Depending on the size, location, and severity of the leak, a
system may be shut down in controlled manner, for example, or in
the event of an emergency, may be abruptly disconnected from the
power supply and shut down.
[0291] For example, a situation may arise in which, though coolant
is leaking, this does not present an immediate risk of damage to
the computing system or its components yet. In this case, the
computing system may be shut down in controlled manner and turned
off, so that the running applications are closed and data is saved.
Optionally, the applications and/or data may be relocated to other
computing systems or components thereof which are not affected by
the loss of coolant. With such controlled shutdown it can be
ensured that an interruption of coolant flow does not result in a
local overheating in the components connected to the cooling
circuit.
[0292] The system for detecting loss of coolant may receive a
command for emergency stop through the communication interface.
With this emergency stop, the entire computing system or portions
of the computing system may be disconnected from power supply, for
example, and/or the pumps for circulating the coolant may be
switched off. In this way, possible damage to components of the
computing system or computing center caused by cooling water can be
avoided or reduced. Further, it is conceivable that the emergency
shutdown involves a pump by which, in case a loss of fluid is
detected, a negative pressure is generated in the coolant system.
For example, the pump may pump out the liquid into a designated
reservoir or into drains. Due to the resulting negative pressure,
no or only little additional water will leak, so that the damage in
the system will remain localized. Furthermore, the cooling fluid
conduits may be closed using valves, whereby further liquid can be
prevented from leaking from the system.
[0293] There may also arise a situation in which an immediate
danger of damage to the computing system cannot be excluded. In
this case, disconnection of the power supply and the pumps may be
effected immediately, without previously shutting down the
computing system in controlled manner and without closing the
running applications and securing the data.
[0294] In another embodiment of the invention, means for emergency
shutdown are integrated in or adapted to a rack or other component
of the computing system.
[0295] Especially in the case where the cooling system is
configured as an integrated or adapted module, the shutdown of the
cooling module and of the component of the computing system or
computer center made be effected locally, if necessary, without
affecting other components of the computing system or computing
center.
[0296] The procedure of shutting down and switching off is
illustrated in the flow charts of FIG. 38 and FIG. 39.
[0297] FIG. 38 illustrates a controlled shutdown.
[0298] As soon as a leak is detected in a rack, the computing
center will be informed via an electronic interface.
[0299] The computing center will then distribute applications that
run in the section affected by the leakage to other parts of the
system which are not affected by the leakage. Also, the data is
backed up.
[0300] Subsequently, the affected system is shut down and then
separated from the power supply.
[0301] In case of an emergency shutdown, for example due to a major
release of water, the power supply for a rack is disconnected
immediately (immediate shutdown), as shown in FIG. 39. Since in
this example the cooling module which includes the leak controller
will be shut down immediately too, there will be no notification to
the computing center via an electronic interface.
[0302] FIG. 40 schematically illustrates an embodiment of a
computing center 55.
[0303] Computing center 55 comprises a plurality of racks 20 which
in turn comprise individual modules 52, such as servers, hard disk
units, etc.
[0304] In this embodiment, modules 52 are coupled by liquid-based
cooling to a first cooling circuit 21, through which heat is
discharged to the outside via heat exchanger 23.
[0305] A second cooling circuit 22 with a lower feed flow
temperature, which cools the components of the rack by an internal
air circulation, is supplied from a refrigeration machine 8. For
this purpose, a heat exchanger is provided within the racks 20.
[0306] With respect to the individual racks, the first cooling
circuit 21 is combined and the second cooling circuit 22 is
combined. This may be implemented through connection of heat
exchangers 24 to cooling circuit 22 by connecting them in parallel
to cooling circuit 22. It is also conceivable for the heat
exchangers 24 to be connected in succession, so that the cooling
fluid flows from one heat exchanger to the next (not shown).
[0307] Using another external heat exchanger 25, process heat from
the hot section of the refrigeration machine is discharged.
[0308] FIG. 41 shows another exemplary embodiment of a computing
center 55.
[0309] Unless otherwise stated, computing center 55 is similar to
that of the exemplary embodiment illustrated in FIG. 40.
[0310] In contrast to FIG. 40, the first cooling circuit 21 for
processor cooling purposes is in thermal communication with the
cooling circuit of the hot section of the refrigeration machine 8,
through a heat exchanger 31.
[0311] This is possible, because the cooling circuits have a
similar temperature.
[0312] An advantage of this embodiment of the invention is that
consequently only one port has to be provided for discharging waste
heat through heat exchanger 25.
[0313] FIG. 42 shows another embodiment of the invention which is
based on that of FIG. 41.
[0314] In contrast to FIG. 41, a respective refrigeration machine
is provided for each rack 20.
[0315] The waste heat sections of the refrigeration machines are
combined.
[0316] FIG. 43 shows another embodiment of a computing center 55,
in which servers 20 are connected to a cooling module 39 (as
described above).
[0317] The advantage of this embodiment is that for extracting
energy from the system, the cooling modules only have to be
connected to cooling circuit 53 through which heat is discharged to
the outside via heat exchanger 25. It will be understood that this
heat may be used as useful heat.
[0318] FIG. 44 shows an embodiment of the invention in which a
plurality of servers 37 are included in a rack 20, and in which a
cooling circuit of servers 37, which for example is a processor
cooling circuit, is combined across multiple servers to a first
cooling circuit 21, wherein the volume flow of cooling liquid can
be controlled individually for each server using a respective pump
57 and, optionally, an additional valve 33. Heat is transferred to
the environment via recooling heat exchanger 23. Pumps 57 and,
optionally, valves 33 may be controlled in a manner as required by
the respective processor cooling circuit in the servers, for
example based on an evaluation of temperature sensors (not shown).
This allows the volume flow of the coolant in the respective
servers to be regulated to the required amount, furthermore, the
performance of the pumps may be optimally adapted to the required
level, and the temperature difference between inlet and outlet of
the processor cooling circuits may be controlled through the
controllable or adjustable volume flow, for a given amount of heat
to be discharged. It will be understood that this adjustment of the
volume flow is also applicable to more cooling circuits, for
example cooling circuits 21, 22, and 38 as illustrated in FIG.
13.
[0319] FIG. 45 shows a configuration in which a plurality of racks
20 are provided, and in which a cooling circuit for servers 37,
which for example is a processor cooling circuit, is combined
across multiple servers to a first cooling circuit 21, wherein the
volume flow of cooling liquid can be controlled individually for
each server using a valve 33, and wherein the volume flow for each
rack is controlled by a pump. Thus, the volume flow may be set and
controlled separately for each rack 20 and for each server 37. It
will be understood that this adjustment of the volume flow is also
applicable to more cooling circuits, for example cooling circuits
21, 22, and 38 as illustrated in FIG. 13.
[0320] FIG. 46 shows another embodiment of the invention in which a
rack 20 is equipped with individual modules that are illustrated as
servers 37, and in which a cooling circuit is a processor cooling
circuit, for example. In contrast to the embodiments illustrated
above, a bypass 58 is provided for each server, via which cooling
fluid may be directed past the server detouring it, using a valve
33 or a T-shaped branching. By means of a controllable bypass, a
portion of the coolant which flows through the modules, may be
returned in a circuit from the coolant outlet of servers 37 to the
coolant inlet of servers 37 without being passed via the processor
cooling port 21 of the rack and the recooling heat exchanger 23.
This allows to increase the amount of coolant flowing through the
server, and so the temperature difference between coolant outlet
and coolant inlet of the server may be reduced without any need to
increase the flow rate of recooling heat exchanger 23. The bypass
may for example be controlled in function of the individual work
load of the server and/or the individual temperature of the server,
so that the individual server may influence the temperature at its
coolant outlet and coolant inlet in function of the work load. This
may be relevant in conjunction with an optimal design of the
cooling system of an individual computing center (for example, for
adapting the coolant temperatures, avoiding low temperatures due to
large temperature differences and thus preventing condensation,
dimensioning of flow rates).
[0321] Furthermore, the bypass and the so allowed increase of the
amount of coolant flowing through the server permit to achieve a
more homogeneous temperature distribution among all the components
connected to the processor cooling circuit.
[0322] In case of an operating state, for example, in which only
one component out of a plurality of components connected to the
processor cooling circuit of a server generates much heat energy to
be dissipated, and the other components very little, overheating of
this component may be prevented by increasing the flow rate of the
coolant in the individual server without influencing the coolant
flow rate of the overall system.
[0323] In this way, the system may adapt to changing computational
loads or operating conditions by controlling the cooling fluid in
the bypass.
[0324] The bypass and the amount of cooling liquid flowing through
the bypass may be adjusted by means of controllable valves and
controllable pumps. Controlling (not shown) may be accomplished by
the server or from outside the server, and temperature sensors (not
shown) may also be involved.
[0325] It is also possible to provide a bypass across an entire
rack instead for individual servers (not shown), for example across
heat exchangers 24 of the second cooling circuit 22 or another
system of the computing center (for example a power supply). The
operation thereof corresponds to that of a bypass across a
server.
[0326] It will be understood that the bypass is also applicable to
more cooling circuits, for example cooling circuits 21, 22, and 38
as illustrated in FIG. 13.
[0327] FIG. 47 shows another embodiment of the cooling system
including a bypass similarly to that illustrated in FIG. 46, but
with the difference that the cooling liquid is not returned from
the outlet of the processor cooling circuit of server 37 to the
inlet of the processor cooling circuit of server 37, rather cooling
liquid is directed past the server detouring it. In this way, the
volume flow in the coolant circuit for cooling the processor may be
reduced without affecting the volume flow in recooling heat
exchanger 23. Another advantage of this bypass is that it allows to
reduce a pressure loss in servers with low work load.
[0328] A cooling system in the sense of the invention may consist
of a number of cooling circuits which may be connected together in
different ways. As for example illustrated in FIG. 9 and in FIG.
13a, these cooling circuits may be connected to form a circuit in
which the different individual cooling circuits are connected in
series, wherein the individual cooling circuits connected in series
have a different temperature level (provided that each of these
individual circuits absorbs thermal energy), but the volume flow in
all cooling circuits connected in series is identical. Each cooling
circuit is affected by a pressure loss which adds up in cooling
circuits connected in series and which has to be compensated for by
the pumps of the cooling circuit. In case a module (such as a
server) of the coolant circuit, or a plurality of modules (for
example servers) has/have a lower work load and less thermal energy
to be discharged, the described bypass permits to individually
reduce the volume flow of coolant in the server with less work load
without thereby reducing the volume flow in the other servers
connected in series. Since a bypass usually exhibits a
significantly lower pressure loss than the cooling circuit in a
module (because the bypass extends over short lengths of coolant
conduits, while in a module, for example in a server, the cooling
circuit extends over longer conduits lengths, for example via
multiple processors or other power components) the pressure loss to
be compensated for by the pumps and thus the required pumping
capacity will also be reduced. In this way, the described bypass
permits to adapt the required pumping capacity to the individual
thermal load to be cooled in each of the modules cooled by cooling
circuits, for example servers, in function of the design and
configuration of the cooling system.
[0329] A bypass may also be provided across an entire rack, for
example across heat exchangers 24 of the second cooling circuit 22,
or across another system of the computing center (for example a
power supply) instead for individual servers (not shown). The
operation thereof corresponds to that of a bypass across a
server.
[0330] FIG. 48 shows another embodiment of the invention, which is
based on that of FIG. 40. In contrast to FIG. 40 it is illustrated
by way of example that the refrigeration machine is not located in
the computing center but outside, here illustrated adjacent to heat
exchangers 23, 25, and 56.
[0331] As another difference to FIG. 40, free cooling is
illustrated, with the cooling fluid of the second cooling circuit
22 first being passed through free cooling heat exchanger 56,
before being fed to the inlet 14 of the cold section 16 of
refrigeration machine 8. Thereby, the cooling fluid is cooled at
heat exchanger 56 by an amount of .DELTA.T, depending, inter alia,
on the ambient conditions (e.g. temperature), thus reducing the
cooling power to be provided by refrigeration machine 8 and hence
the energy consumption thereof. Depending on the ambient conditions
of heat exchanger 56, the full cooling capacity for the second
cooling circuit 22 may possibly be provided by free cooling, for
example in case of low ambient temperatures of, for example, less
than 10.degree. C.
[0332] FIG. 49 shows another exemplary embodiment of the invention
which is based on that of FIG. 40. In contrast to FIG. 40, here,
the second cooling circuit is connected to a cold water supply 63
which is made available to the computing center. This cold water
supply may for example be supplied with cooling energy by a
refrigeration machine not located in the computing center, or by an
ordinary water supply connection, or by a geothermal cooling
system.
[0333] FIG. 50 schematically illustrates another exemplary
embodiment of a computing center 55 which involves recovery of
electric energy from thermal energy.
[0334] Computing center 55 comprises a plurality of racks 20 which
in turn comprise individual modules 52, such as servers, hard disk
units, etc.
[0335] In this embodiment, modules 52 are in thermal communication
with a first cooling circuit 21, via liquid-based cooling.
[0336] A second cooling circuit 22 with a lower feed flow
temperature, which cools the components of the rack in an internal
air circulation, is supplied by a refrigeration machine 8. For this
purpose, a heat exchanger is provided within rack 20. This cooling
circuit is only shown in phantom here, the cooling circuit is not
shown.
[0337] With respect to the individual racks, at least the first
cooling circuit 21 is combined.
[0338] The exemplary embodiment comprises a thermoelectric
generator, or Peltier element 66. The first cooling circuit with a
feed flow temperature T1 first extends to a heat exchanger (hot
side) 67 of an element for generating electric energy, which is in
thermal communication with one side of thermoelectric generator 66.
Another heat exchanger (cold side) 68 of the element for generating
electric energy is in thermal communication with the other side of
thermoelectric generator 66, the return flow temperature of this
heat exchanger (cold side) 68 being T2. The heat exchanger (cold
side) 68 is in thermal communication, through a cooling circuit,
with recooling heat exchanger 25.
[0339] Thus, the temperature difference at thermoelectric generator
66 is .DELTA.T=T1-T2. In this manner, electric energy is generated,
which in this embodiment is fed as recycled energy 70 via an
inverter 69 into the power supply, so that the electric energy
required for the power supply of the computing center 65 is reduced
by the recycled energy 70, assuming that an approximately constant
amount of energy is provided to power the components of the
computing center 64.
[0340] Thus, thermal energy may be converted into electric energy
which is supplied to the computing center, thereby reducing the
amount of electric energy required for the power supply of a
computing center.
[0341] Moreover, the amount of thermal energy to be discharged by
recooling heat exchanger 25 is reduced, which results in reduced
operating costs for the heat exchanger.
[0342] It will be understood that other physical effects for
generating electric energy from thermal energy or based on a
temperature difference .DELTA.T may likewise be used; for example,
instead of thermoelectric generator 66, a mechanical generator
based on the Carnot cycle may be used, for example, an ORC (organic
rankine cycle) machine which drives an electric generator to
produce energy. Also, a Stirling engine may be used. Moreover, a
thermo-magnetic generator may be used.
[0343] Since in some physical processes for converting thermal
energy into a different form of energy, the efficiency thereof is
proportional to the temperature difference .DELTA.T provided (for
example in the Carnot cycle), the system according to the invention
for cooling a computing system which provides a first cooling
circuit with a high temperature permits or at least better promotes
a conversion of thermal energy from a computing center into
electric energy.
[0344] The invention enables to considerably reduce the power
consumption required to cool a computing system.
LIST OF REFERENCE NUMERALS
[0345] 1 System for cooling a computing system [0346] 2 Feed flow
first cooling circuit [0347] 3 Return flow first cooling circuit
[0348] 4 Inlet second cooling circuit [0349] 5 Outlet second
cooling circuit [0350] 6 Liquid-cooled components [0351] 7
Air-cooled components [0352] 8 Refrigeration machine [0353] 9
Evaporator [0354] 10 Compressor [0355] 11 Condenser [0356] 12
Expansion valve [0357] 13 Coolant circuit of compressor unit [0358]
14 Inlet [0359] 15 Outlet [0360] 16 Cold section [0361] 17 Inlet
[0362] 18 Outlet [0363] 19 Hot section [0364] 20 Rack [0365] 21
First cooling circuit [0366] 22 Second cooling circuit [0367] 23
Heat exchanger (recooling) [0368] 24 Heat exchanger (rack cooling)
[0369] 25 Heat exchanger (recooling) [0370] 26 Module [0371] 27 Fan
[0372] 28 Port [0373] 29 Port [0374] 30 Computing system [0375] 31
Heat exchanger [0376] 32 Cooling circuit hot section [0377] 33
Valve [0378] 34 First group of heat generating components [0379] 34
Second group of heat generating components [0380] 36 Third group of
heat generating components [0381] 37 Server [0382] 38 Third cooling
circuit [0383] 39 Cooling module [0384] 40 Controller [0385] 41
Port (recooling) [0386] 42 Leak detection [0387] 43 Port processor
cooling [0388] 44 Port rack cooling [0389] 45 Housing [0390] 46
Heat exchanger [0391] 47 Air circulation [0392] 48 Server [0393] 49
Port [0394] 50 Fan [0395] 51 Blade server [0396] 52 Module [0397]
53 Cooling circuit [0398] 54 Conduit [0399] 55 Computing center
[0400] 56 Heat exchanger (for free cooling) [0401] 57 Pump [0402]
58 Bypass [0403] 59 Heat exchanger of refrigeration machine [0404]
60 Coolant ports [0405] 61 Rack cooling module [0406] 62 Air flow
of blade server [0407] 63 Cold water supply [0408] 64 Electric
energy to power components of the computing center [0409] 65
Electric energy to power the computing center [0410] 66
Thermoelectric generator, Peltier element [0411] 67 Heat exchanger
for element for generating electric energy, hot side [0412] 68 Heat
exchanger for element for generating electric energy, cold side
[0413] 69 Inverter [0414] 70 Recycled electric energy
* * * * *