Refrigeration – Processes – Circulating external gas
Reexamination Certificate
1999-03-29
2001-03-27
Doerrler, William (Department: 3744)
Refrigeration
Processes
Circulating external gas
C062S259200, C361S700000
Reexamination Certificate
active
06205796
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention is generally directed to cooling electronic systems. More particularly, the present invention is directed to cooling electronic computer systems to temperatures which are sufficiently low that moisture condensation becomes a problem. Even more particularly, the present invention is directed to a method and system for controlling water vapor in an enclosed environment.
As electronic circuit chips become available with more densely packed circuit components, the thermal energy flux produced by these devices increases significantly. Additionally, as these devices are operated at increased clock cycle frequencies, the power required by and within these devices also increases. Accordingly, cooling of electronic circuit components has become an increasingly more significant problem as a result of changes which are continuing to occur in the underlying technology.
A very significant thermophysical behavior is that by operating electronic circuit components, such as computer processors, at lower junction temperatures, these devices run at higher speeds. However, as the junction temperature of these devices decreases through the use of cooling mechanisms, there is a concomitant problem produced because the temperature of the outer surface of the package housing also decreases. Eventually, as the temperature is lowered, the temperature of the outer skin of the package, including electrical interconnections, drops below the dew point temperature of the ambient atmosphere and water starts to condense and then may even freeze. This water vapor has the propensity to cause electrical short circuits. Accordingly, it is seen that an electronic component packaging configuration must be developed which controls the concentration of water vapor in the environment immediately surrounding a sufficiently cooled electronics component or package. Alternatively, packaging configurations which eliminate airborne water vapor must be developed. Accordingly, methods and systems should be developed for controlling water vapor in the environment surrounding an electronic circuit package which is cooled to a temperature which is below the dew point of the ambient atmosphere surrounding the electronics package.
SUMMARY OF THE INVENTION
In accordance with one embodiment of the present invention, a cooled electronic system comprises an electronic module in thermal contact with a cold plate containing channels through which a refrigerant can flow. The module and cold plate are disposed in a thermally insulated enclosure which is sealed against the entry of substantial amounts of ambient air. There is provided a refrigeration mechanism which is located outside of the enclosure for supplying refrigerant to the cold plate. Refrigerant conduits passing through the enclosure in a sealed fashion form a closed refrigerant loop for cooling the electronic module. In this embodiment, water vapor control is at least partially dependent upon the sealed nature of the enclosure. Additionally, this embodiment may also employ an internally or externally disposed tank of dry air as a means for maintaining a positive pressure of air within the enclosure.
In another embodiment of the present invention, water vapor control is provided by a mechanism which removes water vapor from ambient air within the enclosure. In this particular embodiment, the water vapor removal means are optionally provided outside of the enclosure. In a preferred embodiment, the water vapor removal mechanism includes a desiccant disposed within a closed exterior container. An air circulating pump moves air from within the sealed enclosure through the desiccant to remove water vapor and then recirculates the dried air through transport conduits back into the enclosure. The desiccant material is periodically purged of its water content.
In another embodiment of the present invention, a refrigeration mechanism, similar to the embodiment described above, is employed within the same enclosure that contains the components which are to be cooled. However, in this particular embodiment, the electronic system preferably comprises a first set of electronic components through which air cooling alone is sufficient, together with a second set of electronic components for which air cooling is not sufficient. That is to say the second set of electronic components is cooled directly with a cold plate as described above using a refrigerant flowing through it. However, as a further aspect of this embodiment, the refrigerant is also directed via additional conduits through an air/refrigerant heat exchanger and back to the refrigerant cooling mechanism. An air moving (AMD) device moves air through the heat exchanger and past the first set of electronic components for which this air cooling is sufficient. Thus, there is provided a water vapor control mechanism which is particularly applicable to the electronic module which is cooled using a cold plate while at the same time there is provided a mechanism for producing air cooling of the other, typically less critical, electronic circuit components.
In a still further embodiment of the present invention, rather than cooling the cold plate directly with refrigerant, a heat exchanger is provided to remove heat from a heat exchange fluid such as a brine which flows through the cold plate. This cooling system provides a mechanism in which dual heat exchange fluids are employed. As in the previous embodiment, this embodiment also preferably includes a heat exchanger for exchanging heat between air and the heat exchange fluid such as brine which flows through the cold plate and its associated conduits. As above, an air moving device directs air through this second heat exchanger and provides cooling for the air coolable portions of the electronic system. This system is also adaptable for the diversion of a portion of the refrigerant in the first heat exchanger to a humidity control device which is contained within a surrounding enclosure. Thus, in this embodiment, the refrigerant not only acts as the cooling mechanism, but also provides a mechanism for removing water vapor from the enclosed environment.
Accordingly, it is an object of the present invention to operate electronic systems, particularly computer systems, at lower temperatures.
It is also an object of the present invention to prevent the build up of moisture on cooled electronic circuit components.
It is a still further object of the present invention to control the water content of the ambient atmosphere surrounding a cooled electronic system, circuit or module or processor.
It is a still further object of the present invention to provide a means or mechanism for utilizing multiple heat exchange fluids for optimal transport of thermal energy away from electronic circuit components.
It is yet another object of the present invention to provide a cooling system for an electronic system which is reliable and which exhibits component redundancy sufficient to maintain long-term availability of the electrical system being cooled.
It is also an object of the present invention to provide a cooled electronic system which is capable of stand-alone operation requiring minimal servicing and maintenance.
It is an even still further object of the present invention to provide a cooling system for less critical air-cooled components while at the same time providing a cooling mechanism for electronic circuit components having more critical cooling needs.
It is a still further object of the present invention to provide a cooled electronic system without the production of external moisture, sweating or dripping.
It is also an object of the present invention to maintain a low humidity condition within an enclosure containing a coolable electronic system, particularly a computer or a computer processor system.
It is yet another object of the present invention to provide a desiccant-based water removal system which is operable continuously and which is periodically purgable of its water content.
Lastly, but not limited hereto, it is an object of t
Chrysler Gregory M.
Chu Richard C.
Simons Robert E.
Doerrler William
International Business Machines - Corporation
Neff Lily
Wojnicki, Jr. Andrew J.
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