System and method for electronic chassis and rack mounted electronics with an integrated subambient cooling system
According to one embodiment of the invention, a cooling system for a heat-generating structure that is disposed in an environment having an ambient pressure comprises a fluid coolant and three structures. The first structure allows the heat generating structure to removably couple to the cooling system. The second structure reduces a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure. The third structure directs a flow of the fluid coolant in the form of a liquid at the subambient pressure in a manner causing the fluid coolant to be brought into thermal communication with the heat-generating structure where heat from the heat-generating structure causes the fluid coolant in the form of the liquid to boil and vaporize so that the fluid coolant absorbs heat from the heat-generating structure as the fluid coolant changes state.
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This invention relates generally to the field of cooling systems and, more particularly, to a system and method for electronic chassis and rack mounted electronics with an integrated subambient cooling system.
BACKGROUND OF THE INVENTIONChassis mounted electronics continue to generate higher and higher levels of heat or thermal energy. With the generation of such thermal energy, such chassis mounted electronics need to be cooled to prevent overheating. However, conventional cooling systems do not always meet the current or future needs for such chassis based systems.
SUMMARY OF THE INVENTIONAccording to one embodiment of the invention, a cooling system for a heat-generating structure that is disposed in an environment having an ambient pressure comprises a fluid coolant and three structures. The first structure allows the heat generating structure to removably couple to the cooling system. The second structure reduces a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure. The third structure directs a flow of the fluid coolant in the form of a liquid at the subambient pressure in a manner causing the fluid coolant to be brought into thermal communication with the heat-generating structure where heat from the heat-generating structure causes the fluid coolant in the form of the liquid to boil and vaporize so that the fluid coolant absorbs heat from the heat-generating structure as the fluid coolant changes state.
Certain embodiments of the invention may provide numerous technical advantages. For example, a technical advantage of one embodiment may include the capability to enhance cooling capability for chassis based systems. Other technical advantages of other embodiments may include the capability to enable flexibility in the integration of a cooling system with a heat generating structure or the capability to compensate for adverse orientations, including tilting, that may be experienced by a cooling system.
Although specific advantages have been enumerated above, various embodiments may include all, some, or none of the enumerated advantages. Additionally, other technical advantages may become readily apparent to one of ordinary skill in the art after review of the following figures and description.
BRIEF DESCRIPTION OF THE DRAWINGSFor a more complete understanding of example embodiments of the present invention and its advantages, reference is now made to the following description, taken in conjunction with the accompanying drawings, in which:
It should be understood at the outset that although example embodiments of the present invention are illustrated below, the present invention may be implemented using any number of techniques, whether currently known or in existence. The present invention should in no way be limited to the example embodiments, drawings, and techniques illustrated below, including the embodiments and implementation illustrated and described herein. Additionally, the drawings are not necessarily drawn to scale.
As briefly referenced in the Background, current cooling systems do not always meet the current or future needs for chassis based systems. The teachings of certain embodiments of the invention recognize that systems that rely purely on convection or conduction cooling provide limited heat removal capability. Some air flow systems require 4° C. inlet air to maintain the component temperatures limits, thereby causing undesirably large temperature gradients. Other air flow systems operating at higher temperatures (e.g., 49° C.) require undesirably high air mass flow rates. Additionally, with conventional systems, there is little, if any, flexibility in the integration of the cooling system with the structure in which they are cooling. Accordingly, teachings of some embodiments of the invention recognize a cooling system that enhances cooling capability for chassis based systems. Additionally, teachings of some embodiments of the invention recognize a cooling system that enables flexibility in the integration of the cooling system with a heat generating structure.
Cooling systems may additionally be subjected to adverse orientations in adverse environments that tilt and rock the cooling systems. Accordingly, teachings of some embodiments of the invention recognize components that may be utilized in a cooling system to compensate for such adverse orientations.
The circuit card assembly 12 may be arranged and designed to conduct heat or thermal energy from the electronic or circuit components on the circuit card assembly 12 to the channels 23, 24. To receive this thermal energy or heat, the channels 23, 24 may be disposed on an edge of the circuit card assembly or may extend through portions of the circuit card assembly 12, for example, through a thermal plane of circuit card assembly 12. In particular embodiments, the channels 23, 24 may extend up to the circuit components, directly receiving thermal energy from the circuit components. Although two channels 23, 24 are shown in the embodiment of
In operation, a fluid coolant flows through each of the channels 23, 24. As discussed later, this fluid coolant may be a two-phase fluid coolant, which enters inlet conduits 25 of channels 23, 24 in liquid form. Absorption of heat from the circuit card assembly 12 causes part or all of the liquid coolant to boil and vaporize such that some or all of the fluid coolant leaves the exit conduits 27 of channels 23, 24 in a vapor phase. To facilitate such absorption or transfer of thermal energy, the channels 23, 24 may be lined with pin fins or other similar devices which increase surface contact between the fluid coolant and walls of the channels 23, 24. Additionally, in particular embodiments, the fluid coolant may be forced or sprayed into the channels 23, 24 to ensure fluid contact between the fluid coolant and the walls of the channels 23, 24.
The fluid coolant departs the exit conduits 27 and flows through the condenser heat exchanger 41, the expansion reservoir 42, a pump 46, and a respective one of two orifices 47 and 48, in order to again to reach the inlet conduits 25 of the channels 23, 24. The pump 46 may cause the fluid coolant to circulate around the loop shown in
The orifices 47 and 48 in particular embodiments may facilitate proper partitioning of the fluid coolant among the respective channels 23, 24 , and may also help to create a large pressure drop between the output of the pump 46 and the channels 23, 24 in which the fluid coolant vaporizes. The orifices 47 and 48 may have the same size, or may have different sizes in order to partition the coolant in a proportional manner which facilitates a desired cooling profile.
A flow 56 of fluid (either gas or liquid) may be forced to flow through the condenser heat exchanger 41, for example by a fan (not shown) or other suitable device. In particular embodiments, the flow 56 of fluid may be ambient fluid. The condenser heat exchanger 41 transfers heat from the fluid coolant to the flow 56 of ambient fluid, thereby causing any portion of the fluid coolant which is in the vapor phase to condense back into a liquid phase. In particular embodiments, a liquid bypass 49 may be provided for liquid fluid coolant that either may have exited the channels 23, 24 or that may have condensed from vapor fluid coolant during travel to the condenser heat exchanger 41.
The liquid fluid coolant exiting the condenser heat exchanger 41 may be supplied to the expansion reservoir 42. Since fluids typically take up more volume in their vapor phase than in their liquid phase, the expansion reservoir 42 may be provided in order to take up the volume of liquid fluid coolant that is displaced when some or all of the coolant in the system changes from its liquid phase to its vapor phase. The amount of the fluid coolant which is in its vapor phase can vary over time, due in part to the fact that the amount of heat or thermal energy being produced by the circuit card assembly 12 will vary over time, as the circuit card assembly 12 system operates in various operational modes.
Turning now in more detail to the fluid coolant, one highly efficient technique for removing heat from a surface is to boil and vaporize a liquid which is in contact with a surface. As the liquid vaporizes in this process, it inherently absorbs heat to effectuate such vaporization. The amount of heat that can be absorbed per unit volume of a liquid is commonly known as the latent heat of vaporization of the liquid. The higher the latent heat of vaporization, the larger the amount of heat that can be absorbed per unit volume of liquid being vaporized.
The fluid coolant used in the embodiment of
Water boils at a temperature of approximately 100° C. at an atmospheric pressure of 14.7 pounds per square inch absolute (psia). In particular embodiments, the fluid coolant's boiling temperature may be reduced to between 55-65° C. by subjecting the fluid coolant to a subambient pressure of about 2-3 psia. Thus, in the embodiment of
In particular embodiments, the fluid coolant flowing from the pump 46 to the orifices 47 and 48 may have a temperature of approximately 55° C. to 65° C. and a pressure of approximately 12 psia as referenced above. After passing through the orifices 47 and 48, the fluid coolant may still have a temperature of approximately 55° C. to 65° C., but may also have a lower pressure in the range about 2 psia to 3 psia. Due to this reduced pressure, some or all of the fluid coolant will boil or vaporize as it passes through and absorbs heat from the channels 23 and 24.
After exiting the exits ports 27 of the channels 23, 24, the subambient coolant vapor travels to the condenser heat exchanger 41 where heat or thermal energy can be transferred from the subambient fluid coolant to the flow 56 of fluid. The flow 56 of fluid in particular embodiments may have a temperature of less than 50° C. In other embodiments, the flow 56 may have a temperature of less than 40° C. As heat is removed from the fluid coolant, any portion of the fluid which is in its vapor phase will condense such that substantially all of the fluid coolant will be in liquid form when it exits the condenser heat exchanger 41. At this point, the fluid coolant may have a temperature of approximately 55° C. to 65° C. and a subambient pressure of approximately 2 psia to The fluid coolant may then flow to pump 46, which in particular embodiments 46 may increase the pressure of the fluid coolant to a value in the range of approximately 12 psia, as mentioned earlier. Prior to the pump 46, there may be a fluid connection to an expansion reservoir 42 which, when used in conjunction with the pressure controller 51, can control the pressure within the cooling loop. 3 psia.
It will be noted that the embodiment of
Although components of one embodiment of a cooling system 10 have been shown in
Thermal energy from the circuit card assembly 112 boils or vaporizes at least a portion of the subambient fluid coolant, allowing in particular embodiments a high heat flux or high heat load. The fluid coolant exits the channels 124 disposed in the coldwalls 163 in a substantially vapor state. The heat inherent within the vapor fluid coolant is then removed as the vapor fluid coolant travels through the condensing heat exchanger in the end piece 160. To facilitate this removal, the end piece 160 may include vents 157 (only one shown in
The chassis 262 includes an inner chassis wall 265, which can be coupled to the channels 223, 224 in a variety of manners, including, but not limited to, bolting, clamping, or use of a variety of actuating devices. Thermal energy or heat may be conducted from components of the circuit card assembly 212 to the inner chassis wall 265 to the channels 223, 224. From the channels 223, 224, the thermal energy or heat may be transferred through the remaining portion of the cooling system 200 in a similar manner to that described above with reference to
With the embodiment of
Similar to the embodiments of
The cooling system 300 of
One or more electronic chassis 362 may respectively be plugged into the manifold 308 to obtain cooling functionality. The chassis 362 may have a fluid channel 324 in its wall, which contain an inlet port 325 (e.g., for substantial liquid fluid coolant) and an exit port 327 (e.g., for substantially vapor fluid coolant). The inlet port 325 and the exit port 327 of the electronic chassis 362 may respectively be fluidly coupled to the manifold 308 using a variety of fluid coupling techniques, including but not limited to techniques which utilize seals, O-rings, and other devices. In this embodiment, each chassis 362 may utilize the centralized cooling system 300 without having its own separate cooling system.
Although the chassis 362 has been described as fluidly coupling to a coolant manifold 308 in the rack 380 in this embodiment, in other embodiments, the rack 380 may provide a series of coolant channels plumbed into the walls of the rack 380. Accordingly, each chassis 362 would simply slide into its allocated slot where it may be coupled or clamped to the coolant channels in a manner similar to that described above with reference to
With reference to
When the channel 724 is level as shown in
In the embodiment of
In particular embodiments, the feed passage 906 may be disposed in a separate sheet of material within the channel 924. For example, the passages 902 may be directly adjacent the plane of thermal transfer while the feed passage 906 is at least one layer removed from the plane of thermal transfer. Controlled liquid coolant may be forced into the bottom of each respective feed hole 905 up through passages 902 transversing the plurality of pin fins 906. As the liquid fluid coolant boils to a vapor state, the vapor in each passage 902 will move up to the common vapor passage 904. If the channel 924 is tilted, liquid coolant may run out of one of the passages 902, cascading over another passage 902. However, vapor may still escape to the common vapor passage 904 and out an exit port 927. Each one of the passages 902 may correspond to a board for a circuit card assembly or another location where heat may be expected.
Although the present invention has been described with several embodiments, a myriad of changes, variations, alterations, transformations, and modifications may be suggested to one skilled in the art, and it is intended that the present invention encompass such changes, variations, alterations, transformation, and modifications as they fall within the scope of the appended claims.
Claims
1. A cooling system for a heat-generating structure disposed in an environment having an ambient pressure, the cooling system comprising:
- a fluid coolant;
- a structure which reduces a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure.
- a channel in thermal communication with the heat generating structure, the channel comprising a plurality of passages, the channel having an inlet port and an exit port, the inlet port operable to receive fluid coolant into the channel substantially in the form of a liquid, and the exit port operable to dispense of fluid coolant out of the channel substantially in the form of a vapor;
- a structure which directs a flow of the fluid coolant in the form of a liquid into the channel through the inlet port, heat from the heat-generating structure causing the fluid coolant in the form of a liquid to boil and vaporize in the channel so that the fluid coolant absorbs heat from the heat-generating structure as the fluid coolant changes state; and
- a vapor passage in fluid communication with the exit port, each of the plurality of passages in fluid communication with the vapor passage, the fluid communication between the plurality of passages and the vapor passage inhibiting blockage of the exit port when the channel is subjected to adverse orientations.
2. A cooling system for a heat-generating structure disposed in an environment having an ambient pressure, the cooling system comprising:
- a fluid coolant;
- a structure which allows the heat generating structure to removably couple to the cooling system;
- a structure which reduces a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure; and
- a structure which directs a flow of the fluid coolant in the form of a liquid at the subambient pressure in a manner causing the fluid coolant to be brought into thermal communication with the heat-generating structure, the heat from the heat-generating structure causing the fluid coolant in the form of the liquid to boil and vaporize so that the fluid coolant absorbs heat from the heat-generating structure as the fluid coolant changes state.
3. The cooling system of claim 2, wherein
- the heat generating structure is disposed within a chassis, and
- the chassis is operable to removably couple to the cooling system.
4. The cooling system of claim 3, wherein
- at least one fluid channel is disposed within the chassis, and
- the at least one fluid channel is a portion of the structure which directs the flow of the fluid coolant to bring the fluid coolant into thermal communication with the heat generating structure.
5. The cooling system of claim 3, wherein
- the structure which directs a flow of the fluid coolant includes a fluid manifold operable to direct the fluid coolant to a plurality of chassis,
- each of the plurality of chassis contains a heat generating structure, and
- each of the plurality of chassis is operable to removably couple to the cooling system.
6. The cooling system of claim 5, wherein
- the cooling system is integrated into a rack operable to hold the plurality of chassis, and
- the cooling system is a closed system.
7. The cooling system of claim 5, wherein
- at least one fluid channel is disposed within at least some of plurality of chassis, and
- the at least one fluid channel of the at least some of the plurality of chassis being a portion of the structure which directs the flow of the fluid coolant to bring the fluid coolant into thermal communication with the heat generating structure.
8. The cooling system of claim 7, wherein;
- the at least one fluid channel of the at least some of the plurality of channels include an inlet port and an exit port, the inlet port and the exit port operable to fluidly couple to the fluid manifold.
9. The cooling system of claim 8, wherein;
- the cooling system includes an air removal system operable to remove air that leaks into the cooling system.
10. A cooling system for a heat-generating structure, the cooling system comprising:
- a fluid coolant;
- a channel in thermal communication with the heat generating structure, the channel having an inlet port and an exit port, the inlet port operable to receive fluid coolant into the channel substantially in the form of a liquid, and the exit port operable to dispense of fluid coolant out of the channel substantially in the form of a vapor;
- a structure which directs a flow of the fluid coolant in the form of a liquid into the channel through the inlet port, heat from the heat-generating structure causing the fluid coolant in the form of a liquid to boil and vaporize in the channel so that the fluid coolant absorbs heat from the heat-generating structure as the fluid coolant changes state; and
- a structure within the channel which inhibits blockage of the exit port when the channel is subjected to adverse orientations.
11. The cooling system of claim 10, wherein the structure which inhibits blockage of the exit port includes:
- a vapor passage in fluid communication with the exit port, the vapor passage including at least two fluid, one of the fluid passageway in selective fluid communication with the channel; and
- a device operable to selectively close the one of the fluid passageways when the channel is subjected to adverse orientations.
12. The cooling system of claim 11, wherein the device operable to selectively close the one of the fluid passageways is a check ball, which rolls on to a balls seat to selectively close the one of the fluid passageways.
13. The cooling system of claim 11, wherein the heat-generating structure is disposed in an environment having an ambient pressure, the cooling system further comprising:
- a structure which reduces a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure.
14. The cooling system of claim 10, wherein the channel comprises a plurality of passages and the structure which inhibits blockage of the exit port includes:
- a vapor passage in fluid communication with the exit port, each of the plurality of passages in fluid communication with the vapor passage.
15. A method for cooling a heat-generating structure disposed in an environment having an ambient pressure, the method comprising:
- providing a fluid coolant;
- removably coupling the heat-generating structure to at least a portion of the cooling system;
- reducing a pressure of the fluid coolant to a subambient pressure at which the fluid coolant has a boiling temperature less than a temperature of the heat-generating structure; and
- bringing the fluid coolant into thermal communication with the heat-generating structure, so that the fluid coolant absorbs heat from the heat-generating structure.
16. The method of claim 15, wherein
- the heat generating structure is disposed within a chassis, and
- removably coupling the heat-generating structure to at least a portion of the cooling system includes
- removably coupling the chassis to the cooling system.
17. The method of claim 16, wherein at least one fluid channel is disposed within the chassis, the method further comprising:
- transporting the fluid coolant fluid to the at least one fluid channel to bring the fluid coolant into thermal communication with the heat-generating structure.
18. The method of claim 16, further comprising:
- transporting, through a fluid manifold, the fluid coolant to a plurality of chassis, each of the plurality of chassis containing a heat generating structure, and each of the plurality of chassis operable to removably couple to the cooling system.
19. The method of claim 18, wherein at least one fluid channel is disposed within at least some of the plurality of chassis, further comprising:
- transporting the fluid coolant fluid to the at least one fluid channel of the at least some of plurality of chassis to bring the fluid coolant into thermal communication with the heat-generating structure.
20. The method of claim 19, wherein the at least one fluid channel of the at least some of the plurality of channels include an inlet port and an exit port, further comprising:
- fluidly coupling the inlet port and the exit port of at least one of the fluid channels of the at least some of the plurality of chassis to the fluid manifold.
Type: Application
Filed: Nov 30, 2005
Publication Date: May 31, 2007
Applicant:
Inventors: Richard Weber (Prosper, TX), Kerrin Rummel (Richardson, TX), Albert Payton (Sachse, TX), William Wyatt (Plano, TX)
Application Number: 11/291,041
International Classification: F25D 23/12 (20060101);