COOLING APPARATUS FOR A COMPUTER SYSTEM
The invention relates to a cooling apparatus for a computer system and a method for cooling at least one heat producing component of a computer system. The cooling apparatus for the computer system features an evaporator (2) for a working medium, which can be thermally coupled to the at least one heat producing component of the computer system. In this connection, the cooling apparatus is constructed as a heat engine or as an absorption refrigerator in order to carry out a thermodynamic cycle.
The invention relates to a cooling apparatus for a computer system and to a method for cooling at least one heat producing component of a computer system.
Today's computer systems, for example, so-called server farms, can already feature up to several thousand processors. In light of increasing demand on network services, a continuing rise in the number of processors in future systems is foreseeable. In addition, the increasing capacity of individual processors is accompanied by a rise in the electric power required. Taken together, on the one hand this results in an enormous primary power requirement (power consumption) of large computer systems, and on the other hand in a large quantity of waste heat, which must be transported away from the computer system by means of suitable cooling apparatuses, wherein it is known to employ waste heat for heating purposes or for hot water production and thus to render this useful.
SUMMARY OF THE INVENTIONThe purpose of the invention is to create a cooling apparatus for a computer system, and a method for cooling at least one heat producing component of a computer system, which enables an effective cooling and an efficient and versatile use of waste heat from a computer system.
According to a first aspect of the invention, the problem is solved by means of a cooling apparatus for a computer system which features an evaporator for a working medium, where the evaporator can be thermally coupled to the at least one heat producing component of the computer system, and the cooling apparatus is a heat engine.
For the cooling apparatus, evaporation of the working medium achieves an effective heat absorption, which brings about good cooling properties. In the cooling apparatus, the absorbed heat can be converted in a thermodynamic cycle of the heat engine into mechanical energy, which is usable in manifold ways. For example, a steam turbine having a generator for converting the mechanical energy into electrical power can be employed, and the electrical power can be used to cover a portion of the primary power requirement of the computer system. It also is possible to couple the steam turbine to cooling medium compressors that are used in an air-conditioning system. Air-conditioning systems frequently are used to provide climate control of rooms for computer systems. If a portion of the energy/power required for operating the air-conditioning system is supplied by making useful the waste heat of the computer system, this in turn leads to a decrease in the energy consumption connected with operation of the computer system.
In a preferred improvement of the cooling apparatus, the working medium is a mixture of ammonia and water. A thermodynamic cycle based on this working medium is also termed a Kalina process. This mixture evaporates at temperatures below the maximum possible operating temperature of electronic components, of processors in particular. For this reason, evaporation of this type of working medium is well-suited for cooling the components of a computer system. In addition, an ammonia-rich vapor phase and an ammonia-poor liquid phase arise during evaporation, by means of which the evaporating temperature of the yet liquid portion of the mixture increases during evaporation. The increase brings about good heat transfer properties in the evaporator. If after passing through the steam turbine the steam phase is combined afresh with the unevaporated liquid phase of the working medium, the boiling point is analogously likewise lowered, leading to a lowering of the temperature in the condenser. The greater temperature difference thus achieved between evaporator and condenser leads to a Carnot efficiency which is better than could be achieved with a working medium having a constant boiling point.
According to a second aspect of the invention, the problem is solved by means of a method for cooling at least one heat-producing component of a computer system, with the evaporator being capable of being coupled thermally to the at least one heat producing component of the computer system and the cooling apparatus being an absorption refrigerator.
Heat absorbed in the evaporator can be used for cooling purposes in the cooling apparatus by means of the thermodynamic cycle of the absorption refrigerator. For example, an air-conditioning system can be operated or supported in order to provide climate control for the rooms of the computer system, effectively lowering the primary power requirement connected with operation of the computer system.
According to a third aspect of the invention, the problem is solved by means of a method for which a working medium is at least partially evaporated in an evaporator by means of the generated heat, and a vapor phase of the working medium arising in the course of evaporation is expanded in a steam turbine with the delivery of a mechanical yield.
According to a fourth aspect of the invention, the problem is solved by means of a method for which a working medium is partially evaporated in an evaporator by means of the generated heat, a vapor phase of said working medium arising in the course of a partial evaporation is refrigerated and condensed and the condensed working medium is evaporated in an additional evaporator while absorbing evaporation heat.
The advantages of the third and fourth aspect of the invention correspond to those of the first and second aspect.
In the following, the invention is explained in more detail on the basis of embodiments with the aid of three figures. Shown are:
For the cooling apparatus depicted in
During operation of the cooling apparatus shown in
Driven by means of the condensate pump 9, a working medium 3 flows through the evaporator 2. Said working medium is a liquid which evaporates or partially evaporates at relatively low temperatures at the prevailing pressure conditions within the working medium circuit 3. The working medium is evaporated in the evaporator 2, absorbing, in this connection, a quantity of heat dependent on its heat of evaporation and on the flow rate. For this reason, the lowest temperature to which the evaporator can be brought is the boiling temperature of the working medium in the evaporator 2 at the prevailing pressure in the working medium circuit 3. Due to temperature gradients between the processor 1 and evaporator 2, caused by heat conductance values of the materials employed as well as by heat transmission resistances, particularly at the transition from the processor 1 to the evaporator 2, the temperature of the processor 1 will be somewhat, e.g., several degrees, higher than the boiling temperature of the working medium. Since processors and electronic components in general must not exceed a certain maximum temperature, above which error functions and/or a reduction of the lifespan can result, the working medium is to be selected appropriately such that an acceptable operating temperature is reached at the component during operation.
A mixture of ammonia and water is particularly suited as a working medium. A thermodynamic cycle which is operated with such a working medium is also termed a Kalina process. A distinctive feature of the Kalina process is that an ammonia-rich vapor phase and an ammonia-poor liquid phase arise during evaporation. Changing the ammonia concentration in the liquid phase increases its evaporation temperature, leading to good heat transfer properties in the evaporator 2.
The liquid phase and the vapor phase are separated from one another in the separator 4. The vapor phase is supplied to the steam turbine 5 designed as a low-pressure turbine. It is expanded in the steam turbine 5 while delivering mechanical energy that is conveyed to the generator 6 to generate electrical power. The power generated by the generator 6 can be supplied again to the computer system, reducing the primary power requirement (energy consumption) of the computer system. Alternatively, mechanical energy furnished by the steam turbine 5 can be used in other ways, e.g., in order to operate compressors for air conditioners, which are frequently employed in combination with large computer systems for additional cooling by means of air circulation. The power requirement of a computer system also can be indirectly lowered in this way.
The expanded ammonia-rich vapor leaving the low pressure outlet of the steam turbine 5 is mixed with the ammonia-poor liquid phase isolated by the separator 4 and supplied to the condenser 7. Mixing lowers the boiling point of the working medium, which leads to a reduction in pressure. The pressure difference utilized by the steam turbine 5 consequently increases, which is advantageous for an effective energy conversion in the steam turbine 5. In addition, a lowering of the temperature in the condenser makes the temperature difference attainable between evaporator and condenser greater than could be achieved with a working medium having a constant boiling point. This leads to a correspondingly superior Carnot efficiency.
In the condenser 7, the working medium is chilled to the point of liquefaction and can in turn be supplied to the evaporator 2 by the condensate pump 9, closing the thermodynamic cycle. Alternatively, liquefaction can also occur not until, or during, compression by means of the condensate pump 9.
In order to dissipate condensation heat of the working medium, a cooling-water flow 8 passes through the condenser 7. Said cooling-water flow 8 can be part of a closed circuit in which absorbed heat is emitted, e.g. outside the building to ambient air by means of heat exchangers, or is supplied to a heating system. Alternatively, the cooling-water flow 8 can be a fresh water flow in which absorbed heat then serves, e.g., for hot water production.
For the sake of clarity, only one processor 1 is shown in
For the cooling apparatus of
As with the embodiment shown in
Unlike the embodiment of
The condenser 7 is likewise designed differently in the two embodiments. For the embodiment of
In the embodiment of
Such a construction can easily achieve a thermal coupling of several of the heat producing components to an evaporator 2. An additional advantage of this arrangement is that commercially available cooling elements for liquid cooling that are usually used in the server field can be employed as the first heat exchanger 10. This also enables a possibly aggressive working medium in the working medium circuit 3 to be spatially separated from the computer system, as indicated by a dashed line in
An additional embodiment of a cooling apparatus for a computer system is depicted In
As in the embodiment of
As in the aforementioned embodiments, in the embodiment of
The working medium is partially evaporated in the evaporator 2, with one of the components of the working medium being concentrated in the vapor phase. Said component (ammonia for an ammonia/water mixture, water for a lithium bromide/water mixture) is also referred to as the cooling medium. In the remaining liquid phase the other component of the working medium will correspondingly be present in a concentrated manner. This liquid phase of the working medium is conducted back to the absorber 18 by means of the return line 19, depicted in
The cooling medium-rich working medium is then evaporated in an additional evaporator 16 at low pressure, wherein a choke element can be provided in order to lower the pressure. Due to the low pressure, evaporation heat is absorbed from the cooling circuit 17 at such a low temperature level that the cooling circuit 17 can be employed in order to air-condition a room. Waste heat of the computer system can be used in this way directly, i.e., without a detour via mechanical energy, in order to air-condition the rooms in which the computer system is operated. The overall primary energy requirement for operating the computer system can thus be lowered.
After evaporation, the cooling medium-rich working medium is in turn condensed in the absorber 18 and dissolved in the cooling medium-poor working medium conducted back from the evaporator 2. The condensation heat and heat of solution emitted in this connection is conducted away by the cooling-agent stream 8. In this connection, an auxiliary-medium cycle having an auxiliary medium, e.g., hydrogen gas in the case of an ammonia/water mixture as the working medium, can be additionally provided. The optional return 19 depicted in
The working medium is subsequently again conducted to the evaporator 2 from the absorber 18 with the aid of the working medium pump 9, closing the cycle.
For all three embodiments, the selection of a suitable working medium and a suitable dimensioning of the components can be used to achieve an efficient utilization of waste heat even for a relatively low temperature of the evaporator 2 in the range of 60-100° C. At these temperatures, components of a computer system, processors in particular, can be operated without any danger of error functions and damage.
Features of the embodiments can, of course, be combined with one another in other ways. For example, an indirect heat transmission from the processors 1 to the evaporators 2 by means of the cooling circuit 13 also can be employed in combination with the Kalina cycle shown in
- 1 Processor
- 2 Evaporator
- 3 Working medium circuit
- 4 Separator
- 5 Steam turbine
- 6 Generator
- 7 Condenser
- 8 Cooling-water flow
- 9 Condensate pump
- 10 First heat exchanger
- 11 Second heat exchanger
- 12 Cooling-medium pump
- 13 Cooling circuit
- 14 Cooling surface
- 15 Cooling-air flow
- 16 Additional evaporators
- 17 Cooling circuit
- 18 Absorber
- 19 Return
Claims
1. A cooling apparatus for a computer system, comprising an evaporator for a working medium, wherein the evaporator can be thermally coupled to at least one heat producing component of the computer system and the cooling apparatus is a heat engine.
2. The cooling apparatus according to claim 1, wherein the heat engine comprises a steam turbine.
3. The cooling apparatus according to claim 2, wherein a generator is coupled to the steam turbine for generating electricity.
4. The cooling apparatus according to claim 1, wherein the working medium comprises organic components and has a low boiling temperature.
5. The cooling apparatus according to claim 1, wherein the working medium comprises a mixture of ammonia and water.
6. The cooling apparatus according to claim 5, wherein a separator is provided downstream of the evaporator to separate a vapor phase and a liquid phase of the working medium, and the cooling apparatus is arranged such that the vapor phase is supplied to a steam turbine and, after expansion in the steam turbine, is again merged with the liquid phase.
7. A cooling apparatus for a computer system, comprising an evaporator for a working medium, wherein the evaporator can be thermally coupled to the at least one heat producing component of the computer system and the cooling apparatus is an absorption refrigerator.
8. The cooling apparatus according to claim 7, further comprising an additional evaporator that is thermally coupled to a cooling circuit of an air conditioning system.
9. The cooling apparatus according to claim 7, wherein the working medium comprises a mixture of ammonia and water.
10. The cooling apparatus according to claim 7, wherein the working medium contains lithium bromide.
11. The cooling apparatus according to claim 1, wherein the evaporator is directly connected to the at least one heat producing component through a contact surface.
12. The cooling apparatus according to claim 1, wherein the evaporator is connected to the at least one heat producing component through a heat conducting element.
13. The cooling apparatus according to claim 12, wherein the heat conducting element comprises a heat pipe.
14. The cooling apparatus according to claim 1, wherein the evaporator is connected to the at least one heat producing component through a heat transporting arrangement.
15. The cooling apparatus according to claim 14, wherein the heat transporting arrangement comprises at least a first heat exchanger and a second heat exchanger coupled thereto, wherein the at least one first heat exchanger is directly connected to the at least one heat producing component, and the second heat exchanger is thermally connected to the evaporator.
16. The cooling apparatus according to claim 7, wherein the evaporator is directly connected to the at least one heat producing component through a contact surface.
17. The cooling apparatus according to claim 7, wherein the evaporator is connected to the at least one heat producing component through a heat conducting element.
18. The cooling apparatus according to claim 17, wherein the heat conducting element comprises a heat pipe.
19. The cooling apparatus according to claim 7, wherein the evaporator is connected to the at least one heat producing component through a heat transporting arrangement.
20. The cooling apparatus according to claim 19, wherein the heat transporting arrangement comprises at least a first heat exchanger and a second heat exchanger coupled thereto, wherein the at least one first heat exchanger is connected directly to the at least one heat producing component, and the second heat exchanger is thermally connected to the evaporator.
21. A method for cooling at least one heat producing component of a computer system, wherein
- a working medium is at least partially evaporated in an evaporator by the heat produced, and
- a vapor phase, arising during evaporation of the working medium, is expanded in a steam turbine to produce an output of mechanical power.
22. The method according to claim 21, wherein the output from the steam turbine is used to drive a generator for generating electricity.
23. A method for cooling at least one heat producing component of a computer system, wherein
- a working medium is partially evaporated in an evaporator by the generated heat,
- a vapor phase of the working medium arising during the partial evaporation is cooled and condensed, and
- the condensed working medium is evaporated in an additional evaporator while absorbing evaporation heat.
24. The method according to claim 23, wherein the evaporation heat is removed and used to air condition the surrounding air.
Type: Application
Filed: Nov 4, 2008
Publication Date: May 14, 2009
Inventor: Christoph Konig (Ottobrunn)
Application Number: 12/264,796
International Classification: F28D 15/00 (20060101);