JP2008298394A - Cryogenic refrigeration system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cryogenic refrigeration system for supplying a refrigerant of stable temperature to a body to be cooled. <P>SOLUTION: In this cryogenic refrigeration system, a refrigerator 15, a first heat exchanger 9 and a second heat exchanger 10 are provided inside a cryostat container 6, and a low-temperature probe 2 is cooled by circulation of a refrigerant. The cryogenic refrigeration system is provided with heat equalizers 18a, 18b arranged between the heat exchangers 9, 10 and the low-temperature probe 2 as the body to be cooled and disposed in the middle of a plurality of low-temperature insulated transfer pipes 8 for circulating the refrigerant. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention is applied to a cryogenic refrigeration system that cools an object to be cooled by circulating a refrigerant cooled by a cryogenic refrigerator.

  In a cryogenic refrigeration system, a cryogenic probe of a nuclear magnetic resonance apparatus may be a target of an object to be cooled. A cryogenic refrigeration system with a structure that is difficult to transmit vibration can be placed away from the cryogenic probe by reciprocating the piston and displacer, etc., for cryogenic probes that require cryogenic temperature and low vibration. Is a suitable system (see Patent Document 1, etc.).

  The cryogenic probe is cooled by passing through a cooling stage in which the refrigerant is thermally connected to the heat exchanger and the refrigerator in the cooling device. This is done by circulating into the cold probe. Conventionally, a simple pipe is used as a transfer pipe for connecting a cooling device and a cryogenic probe. The refrigerant sent from the cooling device directly flows into the flow path of the low-temperature probe through the supply transfer pipe, and after passing through the low-temperature probe, is recovered by the cooling device through the recovery transfer pipe and cooled again.

  FIG. 6 shows a configuration example of a cryogenic refrigeration system in which a conventional cooling device 101 and a low-temperature probe 102 are combined, and the role of refrigerant circulation channels and components will be described below.

  In the low temperature probe 102, a first channel 103 and a second channel 104 are provided. The vacuum pump 105 evacuates the cryostat container 106, the flexible tube 107, and the periphery of the first system flow path 103 and the second system flow path 104 of the low temperature probe 102. The transfer pipe 108, the first heat exchanger 109, the second heat exchanger 110, the first cooling stage 111, the second cooling stage 112, and the like are insulated by vacuum.

  The heat insulating material 113 is wound around the transfer pipe 108 that connects the cooling device 101 and the low temperature probe 102 and is used in combination with vacuum heat insulation to reduce thermal contact with the outside. The shield plate 114 has a cylindrical shape in thermal contact with the first cooling stage 111, and is cooled in a state of covering the first cooling stage 111, the second cooling stage 112, and the second heat exchanger 110. Therefore, it plays a role of blocking radiant heat from the outside of the cryostat container 106.

  The refrigerator 115 includes a first cooling stage 111 and a second cooling stage 112 having different temperatures, and has a structure for cooling the refrigerant. In this case, the second cooling stage 112 is cooler than the first cooling stage 111. The compressor 116 serves to supply refrigerant to the refrigerator 115 and the low temperature probe 102. The first heat exchanger 109 and the second heat exchanger 110 have a double pipe structure, and the refrigerant flowing in the inner pipe and the refrigerant flowing between the inner and outer pipes face each other (counterflow). Heat exchange. The flow rate of the refrigerant flowing through the transfer pipe is adjusted by the flow rate control valve 17.

Next, the refrigerant flow path will be described. The refrigerant supplied from the compressor 116 is branched in two directions toward the inside of the refrigerator 115 and the cryostat container 106. The refrigerant that has entered the refrigerator 115 draws heat inside the refrigerator 115 to cool the first cooling stage 111 and the second cooling stage 112, and returns to the inside of the compressor 116 again. On the other hand, the refrigerant supplied to the transfer pipe enters the first heat exchanger 109, exchanges heat with the refrigerant returning to the compressor 116, and is supplied to the first system low-temperature probe channel 103. Here, the temperature of the refrigerant supplied to the first system low-temperature probe channel 103 is about 60K. The refrigerant that has passed through the low-temperature probe flow path 103 of the first system is cooled by the first cooling stage 111 and then exchanges heat with the refrigerant cooled by the second cooling stage 112 in the second heat exchanger 110. It is supplied to the low temperature probe flow path 104 of the second system. The temperature of the refrigerant supplied to the second low-temperature probe channel 104 is about 12 to 15K. The refrigerant that has passed through the second low-temperature probe flow path 104 is cooled by the second cooling stage 112, and the second heat exchanger 110 performs heat exchange with the refrigerant cooled by the first cooling stage 111. Thereafter, the first heat exchanger 109 performs heat exchange with the refrigerant directed to the first-system low-temperature probe flow path 103, and is collected by the compressor 116.
JP 2005-106633 A

  However, when a refrigerator such as a Gifford McMahon refrigerator, a Stirling refrigerator, or a Solvay refrigerator is used as a refrigerator, periodic temperature fluctuations occur in the refrigerator, and the temperature fluctuation is low due to the refrigerant. Detection sensitivity is shaken and transmitted to the probe.

  Then, an object of this invention is to provide the cryogenic refrigeration system which supplies the to-be-cooled body with the refrigerant | coolant whose temperature was stabilized.

  In order to achieve the above object, the cryogenic refrigeration system of the present invention includes a refrigerator and a heat exchanger thermally connected to the refrigerator inside the cryostat container, and the refrigerant is cooled by the heat exchanger. A cryogenic refrigeration system that cools an object to be cooled by circulation of the refrigerant. The cryogenic refrigeration system of the present invention includes a heat equalizer in at least one place in the middle of a plurality of low-temperature-insulated transfer pipes that circulate a refrigerant, which is disposed between a heat exchanger and the object to be cooled. It is characterized by that.

  ADVANTAGE OF THE INVENTION According to this invention, the refrigerant | coolant with which temperature was stabilized can be supplied to a to-be-cooled body by providing a heat equalizer in the transfer pipe arrange | positioned between a heat exchanger and a to-be-cooled body.

  FIG. 1 shows a configuration example of the cryogenic refrigeration system of the present invention. The cryogenic refrigeration system is an embodiment in which a cryogenic probe of a nuclear magnetic resonance apparatus is used as an object to be cooled.

  In the low-temperature probe 2 that is the object to be cooled, a first channel 3 and a second channel 4 are provided. The vacuum pump 5 evacuates the cryostat container 6, the flexible tube 7, the first flow path 3 of the cryogenic probe 2, and the periphery of the second flow path 4 to form a plurality of transfer pipes 8 and a first heat exchange. The apparatus 9, the second heat exchanger 10, the first cooling stage 11, the second cooling stage 12, etc. are vacuum insulated.

  A soaking device 18a is incorporated in the middle of the heat exchanger 9 and the first system low temperature probe channel 3, and a soaking device 18b is installed in the middle of the heat exchanger 10 and the second system low temperature probe channel 4. It has been incorporated. The soaking devices 18a and 18b may be provided in at least one of either one.

  The heat insulating material 13 is wound around the transfer pipe 8 that connects the cooling device 1 and the low temperature probe 2, and is used in combination with vacuum heat insulation to reduce thermal contact with the outside.

  The shield plate 14 has a cylindrical shape in thermal contact with the first cooling stage 11 and is cooled in a state of covering the first cooling stage 11, the second cooling stage 12, and the second heat exchanger 10. Therefore, it plays the role of blocking radiant heat from the outside of the cryostat container 6.

  The refrigerator 15 includes a first cooling stage 11 and a second cooling stage 12 having different temperatures, and has a structure for cooling the refrigerant. In this case, the second cooling stage 12 has a lower temperature than the first cooling stage 11. As the refrigerator 15, a Gifford McMahon refrigerator, a Stirling refrigerator, a Solvay refrigerator, or the like is applicable.

  The compressor 16 serves to supply refrigerant to the refrigerator 15 and the low temperature probe 2.

  The first heat exchanger 9 and the second heat exchanger 10 have a double pipe structure, and the refrigerant flowing in the inner pipe and the refrigerant flowing between the inner and outer pipes face each other (counterflow). Heat exchange. The flow rate of the refrigerant flowing through the transfer pipe is adjusted by the flow rate control valve 17.

  Here, the details of the structure of the heat equalizers 18a and 18b will be described with reference to FIGS.

  FIG. 2 is a side view of the heat equalizer 18a. In addition, since the soaking device 18b has the same structure as the soaking device 18a, here, the soaking device 18a will be described as an example.

  The soaking device 18a has a structure in which one or more tubes are spirally wound and brought into thermal contact with an adjacent tube.

  The soaking device 18a is preferably configured so that one half of the temperature change period of the refrigerant shown in FIG. 3 corresponds to almost one turn of the spiral tube. With such a configuration, as shown in FIG. 4, the portion of the pipe through which the high-temperature refrigerant flows and the portion of the pipe through which the low-temperature refrigerant flow are in thermal contact, and the efficiency of heat exchange increases.

  Further, as shown in FIG. 5, the heat equalizer 18a covers the spiral tube with a metal heat conductor 19a having a large specific heat at a low temperature, for example, a lead heat conductor 19a, and includes a heat transfer body 19a and a spiral tube. A structure in which the gap is filled with a material having good thermal conductivity such as the indium sheet 20 may be used. With such a structure, the efficiency of heat exchange is further improved, the temperature fluctuation of the refrigerant can be reduced, and a refrigerant with a stable temperature can be supplied.

  On the contrary, as shown in FIG. 6, the lead heat transfer body 19b is held in the spiral of the spiral tube, and the gap between the heat transfer body 19b and the spiral tube is made of an indium sheet. It may be filled with 20 or the like.

  With reference to FIG. 1 again, the flow of the refrigerant in the cryogenic refrigeration system of the present invention will be described.

  The refrigerant supplied from the compressor 16 passes through the first heat exchanger 9, passes through the heat equalizer 18 a, reaches a stable temperature, passes through the transfer pipe 8, and passes through the first system low-temperature probe flow path. 3 is supplied.

  The refrigerant that has passed through the low-temperature probe flow path 3 of the first system returns to the cooling device 1, passes through the first cooling stage 11 and the second heat exchanger 10, reaches a stable temperature in the soaking device 18 b, and is transferred It passes through the pipe 8 and is supplied to the low temperature probe flow path 4 of the second system.

  The refrigerant that has passed through the second low-temperature probe flow path 4 returns to the cooling device 1, and is recovered by the compressor 16 through the second cooling stage 12, the second heat exchanger 10, and the first heat exchanger 9. .

  As described above, the cryogenic refrigeration system of the present invention can reduce the fluctuation of the temperature of the refrigerant when it passes through the heat equalizers 18 a and 18 b, and can supply the low-temperature probe 2 with a stable temperature.

It is a figure which shows the structural example of the cryogenic refrigeration system of this invention. It is a side view of the heat equalizer of this invention. It is a graph which shows typically the temperature change period of a refrigerant. It is a side view which shows typically the temperature distribution of a heat equalizer. It is a side view of the other example of the heat equalizer of this invention. It is a side view of the further another example of the heat equalizer of this invention. It is a figure which shows an example of a structure of the conventional cryogenic refrigeration system.

Explanation of symbols

2 cryogenic probe 6 cryostat container 8 transfer pipe 9 first heat exchanger 10 second heat exchanger 15 refrigerator 16 compressor 18a, 18b soaking device

Claims (6)

A cryogenic refrigeration system comprising a refrigerator and a heat exchanger thermally connected to the refrigerator inside the cryostat container, wherein the refrigerant is cooled by the heat exchanger, and the object to be cooled is cooled by circulation of the refrigerant. In the system,
A cryogenic refrigeration comprising a soaking device at least in the middle of a plurality of low-temperature insulated transfer pipes arranged between the heat exchanger and the object to be cooled and circulating the refrigerant. system.   2. The soaking device has a structure in which one or more turns of a pipe serving as a flow path for the refrigerant is spirally wound, and the adjacent spiral pipes are in thermal contact with each other. The cryogenic refrigeration system described.   3. The cryogenic refrigeration system according to claim 2, wherein the heat equalizer is configured such that a half period of a temperature change period of the refrigerant corresponds to one turn of the spiral tube.   The cryogenic refrigeration system according to claim 2 or 3, wherein the soaking device is covered with a thermally connected metal heat transfer body.   The cryogenic refrigeration system according to claim 2 or 3, wherein the heat equalizer holds a thermally connected metal heat transfer body in a spiral.   The cryogenic refrigeration system according to claim 4 or 5, wherein the metal heat transfer body is made of lead.

Images