Refrigeration – Automatic control – Refrigeration producer
Reexamination Certificate
2000-12-28
2004-06-15
Tapolcai, William E. (Department: 3744)
Refrigeration
Automatic control
Refrigeration producer
C062S227000
Reexamination Certificate
active
06748755
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a refrigeration system of a closed cycle, including: a circulation channel through which a refrigerant circulates; and a dry evaporator incorporated in the circulation channel so as to contact a target heating object.
2. Description of the Prior Art
A refrigeration system of a closed cycle is well known to include a so-called dry evaporator. The refrigeration system is often employed in an interior air conditioner, for example. The evaporation of a refrigerant can be promoted within the dry evaporator under a low pressure, so that atmosphere around the dry evaporator can be cooled down. The refrigerant completely evaporates within the dry evaporator in such an interior air conditioner. The quality of the refrigerant is forced to reach 1.0 within the dry evaporator. Only the refrigerant of gas state is intended to be discharged from the dry evaporator.
A cooling system is in general incorporated in a large-sized computer such as a supercomputer and a main frame. The cooling system is designed to cool a semiconductor device module such as a multichip module (MCM). Acceleration of operating clocks and a higher density of electronic elements are predicted to induce the increased quantity of heat in the semiconductor device module. A higher performance of cooling is expected in the cooling system. It is believed that it becomes difficult for a conventional refrigeration system to reliably restrain an increase in the temperature of the semiconductor device module.
The performance of cooling in the dry evaporator may be considered based on the quantity of heat transfer per unit area, namely, a heat transfer coefficient. A higher heat transfer coefficient serves to reliably prevent the semiconductor device module from an excessive increase in the temperature, even when the semiconductor device module suffers from an extreme generation of heat. Heretofore, no specific proposal has been made to increase the quantity of heat transfer per unit area in the technical field of a refrigeration system of a closed cycle.
SUMMARY OF THE INVENTION
It is accordingly an object of the present invention to provide a refrigeration system capable of achieving a higher performance of cooling as compared with a prior art refrigeration system.
According to a first aspect of the present invention, there is provided a refrigeration system comprising: a circulation channel through which a refrigerant circulates; and a dry evaporator incorporated in the circulation channel and designed to keep a quality smaller than 1.0 in evaporating the refrigerant.
In general, the quantity of heat transfer per unit area, namely, a heat transfer coefficient depends on the quality. The heat transfer coefficient remarkably drops when the quality of the refrigerant exceeds a predetermined threshold level before the quality actually reaches 1.0. If the quality of the refrigerant is kept below the predetermined threshold level during vaporization of the refrigerant in the dry evaporator, the dry evaporator is allowed to reliably establish a higher performance of cooling. On the other hand, if a refrigerant completely evaporates in a dry evaporator in a conventional manner, the heat transfer coefficient of the refrigerant remarkably drops after the quality of the refrigerant exceeds the predetermined threshold level. Accordingly, the conventional dry evaporator is forced to absorb heat at a lower heat transfer coefficient, as compared with the dry evaporator of the first aspect. It should be noted that the threshold quality of a refrigerant employed can be set, at a level below 1.0, in an appropriate manner based on the kind of a refrigerant and the capability of cooling required in the dry evaporator.
According to a second aspect of the present invention, there is provided a refrigeration system comprising: a circulation channel through which a refrigerant circulates; a dry evaporator incorporated in the circulation channel and contacting a target heating object; and a subsidiary evaporator incorporated in the circulation channel downstream of the dry evaporator.
It is not necessary to completely evaporate the refrigerant in the dry evaporator of this type of the refrigeration system. The subsidiary evaporator may be employed to accomplish the complete vaporization of the refrigerant, so that the quality of 1.0 is established in the refrigerant discharged out of the subsidiary evaporator. If such a dry refrigerant is supplied to a compressor downstream of the subsidiary evaporator, the compressor can reliably be prevented from a compression of a liquid, which is harmful to the compressor. The dry evaporator contacting a target heating object is allowed to discharge the refrigerant of gas-liquid mixture state. Specifically, the quality of the refrigerant can be kept below a predetermined threshold level during vaporization of the refrigerant in the dry evaporator in the aforementioned manner, so that the dry evaporator is allowed to reliably establish a higher performance of cooling.
According to a third aspect of the present invention, there is provided a method of refrigeration comprising vaporizing a refrigerant within a dry evaporator incorporated in a circulation channel, through which the refrigerant circulates, so as to allow the refrigerant of gas-liquid mixture state to flow out of the dry evaporator.
The method of refrigeration allows the dry evaporator to discharge the refrigerant after incomplete vaporization of the refrigerant in the dry evaporator. The quality of the refrigerant can be kept below a predetermined threshold level during vaporization of the refrigerant in the dry evaporator in the aforementioned manner, so that the dry evaporator is allowed to reliably establish a higher performance of cooling.
The method of refrigeration may further comprise heating the refrigerant flowing out of the dry evaporator so as to completely evaporate the refrigerant of liquid state. If the refrigerant can completely be evaporated before it is introduced into a compressor incorporated in the circulation channel downstream of the dry evaporator, the compressor can reliably be prevented from a compression of a liquid. The compression of a liquid is harmful to the compressor, as conventionally known.
According to a fourth aspect of the present invention, there is provided a refrigeration system comprising: a circulation channel through which a refrigerant circulates; a dry evaporator incorporated in the circulation channel so as to contact a target heating object; a refrigerant outlet defined in the dry evaporator and designed to discharge the refrigerant of gas-liquid mixture state; and a gas-liquid separation filter incorporated in the refrigerant outlet.
Even when the refrigerant is incompletely evaporated in the dry evaporator in this refrigeration system, the gas-liquid separation filter serves to reliably establish the quality of 1.0 for the refrigerant discharged from the dry evaporator. If such a dry refrigerant is introduced into a compressor incorporated in the circulation channel downstream of the dry evaporator, the compressor can reliably be prevented from a compression of a liquid, which is harmful to the compressor. The dry evaporator contacting a target heating object is allowed to discharge the refrigerant of gas-liquid mixture state. Specifically, the quality of the refrigerant can be kept below a predetermined threshold level during vaporization of the refrigerant in the dry evaporator in the aforementioned manner, so that the dry evaporator is allowed to reliably establish a higher performance of cooling.
The respective aforementioned refrigeration systems may include a dry evaporator, comprising: a casing defining a closed space; a refrigerant inlet defined in the casing so as to open at a wall surface; a refrigerant outlet defined in the casing so as to open at a wall surface; and a group of fins inwardly protruding from an inner surface of the casing so as to define a plurality of refrigerant passages extending in para
Ishimine Junichi
Kawashima Hisashi
Kubo Hideo
Mochizuki Masahiro
Suzuki Masahiro
Ali Mohammad M.
Fujitsu Limited
Tapolcai William E.
Westerman Hattori Daniels & Adrian LLP
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