WO1995033164A1 - Method and device for the production of very low temperatures - Google Patents

Method and device for the production of very low temperatures Download PDF

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Publication number
WO1995033164A1
WO1995033164A1 PCT/EP1995/001048 EP9501048W WO9533164A1 WO 1995033164 A1 WO1995033164 A1 WO 1995033164A1 EP 9501048 W EP9501048 W EP 9501048W WO 9533164 A1 WO9533164 A1 WO 9533164A1
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WO
WIPO (PCT)
Prior art keywords
joule
helium
stage
cold head
bar
Prior art date
Application number
PCT/EP1995/001048
Other languages
German (de)
French (fr)
Inventor
Ernst Schilling
Hans-Dieter Sous
Original Assignee
Leybold Aktiengesellschaft
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Leybold Aktiengesellschaft filed Critical Leybold Aktiengesellschaft
Priority to EP95913147A priority Critical patent/EP0760926A1/en
Priority to JP8500205A priority patent/JPH10501055A/en
Publication of WO1995033164A1 publication Critical patent/WO1995033164A1/en

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Classifications

    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F25—REFRIGERATION OR COOLING; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS; MANUFACTURE OR STORAGE OF ICE; LIQUEFACTION SOLIDIFICATION OF GASES
    • F25B—REFRIGERATION MACHINES, PLANTS OR SYSTEMS; COMBINED HEATING AND REFRIGERATION SYSTEMS; HEAT PUMP SYSTEMS
    • F25B9/00—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point
    • F25B9/10—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point with several cooling stages

Definitions

  • the invention relates to a method for generating very low temperatures by relaxing helium in the cold head of a refrigerator and by relaxing helium in a Joule-Thomson stage, which is arranged downstream of the cold head of the refrigerator.
  • the invention also relates to a device suitable for carrying out this method.
  • a method of this type is known from the book "CRYOPUMPING, Theory and Practice" by Rene A. Haefer, 1989.
  • a refrigerator operated according to the Gifford-McMahon principle with a two-stage cold head is used for the implementation.
  • the helium is circulated in a known manner. It is fed to the cold head at 20 bar, expanded to 5 bar in the two cooling stages and returned to the compressor. In a second circuit, helium of approximately 20 bar is fed through a series of five heat exchangers to the narrowest part of the Joule-Thomson stage.
  • the helium is precooled in the heat exchangers with the help of the cold heads of the refrigerator and with the help of the back-flowing helium which is relaxed in the Joule-Thomson stage. In the Joule-Thomson level, the helium is released to 1 bar. In addition to the compressor in the refrigerator-helium circuit, a further compressor is therefore provided which compresses the helium of the Joule-Thomson circuit from 1 bar to 5 bar.
  • the object of the present invention is to simplify the method mentioned at the outset and also the device suitable for carrying out this method and to make it more effective.
  • this object is achieved in a method of the type mentioned in the introduction in that the helium supplied to the Joule-Thomson stage is removed from the cold side of the cold head of the refrigerator.
  • the advantage of this measure is that the gas flowing to the narrow point of the Joule-Thomson stage flows through the cold head beforehand and is not only pre-cooled in this way, but is also cleaned particularly thoroughly. Contaminants, such as hydrogen, methane, oil vapors or the like, which clog the bottleneck of the Joule-Thomson stage, freeze out in the regenerator of the cold head displacer or are retained therein. Separate cleaning stages are no longer necessary. Separate heat exchangers for precooling the helium with the cooling stage or stages of the refractor can also be dispensed with. Further advantages and details of the invention will be explained with reference to an embodiment shown in the figure.
  • the figure shows a two-stage refrigerator operated according to the Gifford-McMahon principle. It comprises the cold head 1 with the housing parts 2 and 3. In the housing part 2, the cylindrical working spaces 4 and 5 for the two displacers 6 and 7 are accommodated.
  • the upper displacer 6 is equipped with a drive piston 8, the associated cylinder 9 of which is accommodated in a guide bush 10, which closes off the working space 4 from the housing part 3.
  • the guide bush 10 is equipped with the bores 11, 12 and 13.
  • the bore 11 opens into the working space 4 and serves to supply this space with working gas.
  • the bore 13 opens into a transverse bore 14 which is connected to an annular groove 15 in the outer wall of the guide bush 10.
  • Two further bores 12 are indicated by dash-dotted lines and serve to pneumatically drive the system consisting of the displacers 6 and 7.
  • the different bores lie in different planes from the plane of the drawing, so that they do not cross each other, which is indicated by the dashed line or dash-dot line.
  • control motor 16 is housed, which actuates the control valve 18 via the shaft 17.
  • This control valve 18 is used in a manner known per se to supply the various bores with working gas under high pressure and under low pressure.
  • the connections for the high-pressure and low-pressure working gas are designated 19 and 20.
  • the parting plane 21 between the housing parts 2 and 3 lies at the level of the control valve 18. It is selected so that after the removal of the upper housing part 3 with the motor 16 and valve 18 A flat pot-shaped space 22 is present above the guide bush 10. At the level of this space 22 there is a bore 23 which penetrates the wall of the housing part 2 and connects the space 22 to the high-pressure connection 19.
  • the low pressure connection 20 is connected to the bore 24 in the housing part 3, which opens into the annular groove 15 of the guide bush 10.
  • the high-pressure working gas flows via the connection 19 into the chamber 22. From there, the various bores are supplied with the aid of the control valve 18. After its expansion in the refrigerator stages, the working gas reaches the bores 13, 14 and flows out via the annular groove 15 and the low-pressure connection 20.
  • the refrigerator also includes the compressor 31, the inlet of which is connected to the low-pressure connection 20 via the line 32 and the outlet of which is connected to the high-pressure connection 19 via the line 33.
  • temperatures of approximately 10 ° Kelvin with an output of 1 watt can be generated in the region of the cold end (flange 34) of the second stage 5, 7 of the cold head 1.
  • the illustrated embodiment is also equipped with the Joule-Thomson stage 35 according to the invention.
  • This includes the passive constriction 36, which can be designed as a nozzle, sintered disk or capillary.
  • the flange 34 of the second cooling stage is provided with a bore 38 into which the pipe section 39 is soldered.
  • This suitably consists of stainless steel so that the second cold stage of the cold head 1 and the Joule-Thomson stage 35 are separated from one another by a thermal resistance.
  • the helium which relaxes and cools down at the constriction 36 flows into a chamber 41.
  • the chamber 41 is filled with metal nets 42.
  • the material for the metal networks is expediently copper or silver. These materials have good thermal conductivity at temperatures below 10 K.
  • the expanded working gas leaves chamber 41 and flows via line 45 to the inlet of a low-pressure compressor 46. This compresses the working gas to the inlet pressure of the compressor 31, so that the outlet of the low pressure compressor can be connected to the line 32 via the line 47.
  • the exemplary embodiment described is expediently operated at the following pressures:
  • the compressor 31 brings the working gas to a pressure of 10 to 30 bar, preferably about 20 bar.
  • the helium is expanded to 2 to 8 bar, preferably about 4 bar.
  • Part of the helium of the refrigerator circuit (approx. 2%), which already has a temperature of approximately 6 K in the area of the cold end 34 of the second stage 5, 7 of the refrigerator, is fed to the constriction 36 of the Joule-Thomson stage. It relaxes there to a pressure of 20 bar to 1 bar, preferably 0.6 bar.
  • the relaxation causes a further temperature reduction, to about 4.2 K.
  • the relaxed and cooled helium flows through the chamber 41 with the nets 42. It leaves the chamber 41 via the line 45 and is fed to the low-pressure compressor 46, which it on Low pressure compressed in the refrigerator circuit.
  • temperatures of approximately 4.5 K with an output of 10 mW can be generated in the region of the flange 43. Temperatures of this order are for the liquefaction of helium or necessary when using liquid helium, for example at
  • the invention can be used in single-stage and multi-stage Gifford-McMahon refrigerators or in similar refrigerators.
  • Old refrigerators that work with regenerative heat exchangers can be equipped. It is essential that the working gas has passed through one or more cooling stages before it is fed to the bottleneck of the Joule-Thomson stage.

Abstract

The invention concerns a method of producing very low temperatures by allowing helium to expand in the cold head (1) of a refrigeration unit and by subsequently allowing the helium to expand in a unit making use of the Joule-Thomson effect (35). To simplify and improve the method, the invention proposes that the helium fed to the unit making use of the Joule-Thomson effect (35) is taken from the cold side (34) of the cold head (1).

Description

Verfahren und Vorrichtung zur Erzeugung sehr tiefer Tempe¬ raturenMethod and device for generating very low temperatures
Die Erfindung bezieht sich auf ein Verfahren zur Erzeugung sehr tiefer Temperaturen durch Entspannen von Helium im Kaltkopf eines Refrigerators und durch Entspannen von Helium in einer Joule-Thomson-Stufe, welche dem Kaltkopf des Refrigerators nachgeordnet ist. Außerdem bezieht sich die Erfindung auf eine für die Durchführung dieses Verfahrens geeignete Vorrichtung.The invention relates to a method for generating very low temperatures by relaxing helium in the cold head of a refrigerator and by relaxing helium in a Joule-Thomson stage, which is arranged downstream of the cold head of the refrigerator. The invention also relates to a device suitable for carrying out this method.
Aus dem Buch "CRYOPUMPING, Theory and Practice" von Rene A. Haefer, 1989, ist ein Verfahren dieser Art bekannt. Der Durchführung dient ein nach dem Gifford-McMahon-Prinzip betriebener Refrigerator mit einem zweistufigen Kaltkopf. Das Helium wird in bekannter Weise im Kreislauf geführt. Es wird mit 20 bar dem Kaltkopf zugeführt, in den beiden Kältestufen auf 5 bar entspannt und zum Kompressor zurück¬ geführt. In einem zweiten Kreislauf wird Helium von etwa 20 bar durch eine Serie von insgesamt fünf Wärmetauschern der Engstelle der Joule-Thomson-Stufe zugeführt. In den Wärme¬ tauschern wird das Helium mit Hilfe der Kaltköpfe des Refrigerators und mit Hilfe des in der Joule-Thomson-Stufe entspannten, zurückströmenden Heliums vorgekühlt. In der Joule-Thomson-Stufe erfolgt eine Entspannung des Helium auf 1 bar. Zusätzlich zum Kompressor im Refrigerator-Helium- Kreislauf ist deshalb ein weiterer Kompressor vorgesehen, der das Helium des Joule-Thomson-Kreislaufs von 1 bar auf 5 bar komprimiert.A method of this type is known from the book "CRYOPUMPING, Theory and Practice" by Rene A. Haefer, 1989. A refrigerator operated according to the Gifford-McMahon principle with a two-stage cold head is used for the implementation. The helium is circulated in a known manner. It is fed to the cold head at 20 bar, expanded to 5 bar in the two cooling stages and returned to the compressor. In a second circuit, helium of approximately 20 bar is fed through a series of five heat exchangers to the narrowest part of the Joule-Thomson stage. The helium is precooled in the heat exchangers with the help of the cold heads of the refrigerator and with the help of the back-flowing helium which is relaxed in the Joule-Thomson stage. In the Joule-Thomson level, the helium is released to 1 bar. In addition to the compressor in the refrigerator-helium circuit, a further compressor is therefore provided which compresses the helium of the Joule-Thomson circuit from 1 bar to 5 bar.
Bei Joule-Thomson-Stufen, die in der beschriebenen Weise zur Erzeugung tiefer Temperaturen eingesetzt werden, besteht der generelle Nachteil, daß sich ihre Engstellen relativ schnell zusetzen. Bei der beschriebenen Einrichtung nach dem Stand der Technik sind deshalb - neben der ohnehin im Kompressor befindlichen Gas-Reinigung - auf dem Weg des zur Engstelle strömenden Heliums mehrere Gas-Reinigungsstufen vorgesehen.The general disadvantage with Joule-Thomson stages, which are used in the manner described for the generation of low temperatures, is that their bottlenecks become clogged relatively quickly. In the described device according to the state of the art, in addition to the gas cleaning which is already in the compressor, several gas cleaning stages are provided on the way of the helium flowing to the constriction.
Der vorliegenden Erfindung liegt die Aufgabe zugrunde, das eingangs erwähnte Verfahren und auch die für die Durchfüh¬ rung dieses Verfahrens geeignete Vorrichtung zu vereinfachen und effektiver zu gestalten.The object of the present invention is to simplify the method mentioned at the outset and also the device suitable for carrying out this method and to make it more effective.
Erfindungsgemäß wird diese Aufgabe bei einem Verfahren der eingangs erwähnten Art dadurch gelöst, daß das der Joule- Thomson-Stufe zugeführte Helium der kalten Seite des Kalt¬ kopfes des Refrigerators entnommen wird. Der Vorteil dieser Maßnahme besteht darin, daß das der Engstelle der Joule- Thomson-Stufe zuströmende Gas vorher den Kaltkopf durch¬ strömt und auf diesem Wege nicht nur vorgekühlt, sondern auch besonders gründlich gereinigt wird. Die Engstelle der Joule-Thomson-Stufe zusetzende Verunreinigungen, wie Was¬ serstoff, Methan, öldämpfe oder dergleichen, frieren im Regenerator des Displacers des Kaltkopfes aus bzw. werden darin zurückgehalten. Gesonderte Reinigungsstufen sind nicht mehr erforderlich. Auch gesonderte Wärmetauscher zur Vor¬ kühlung des Heliums mit der oder den Kältestufen des Refri¬ gerators können entfallen. Weitere Vorteile und Einzelheiten der Erfindung sollen anhand eines in der Figur dargestellten Ausführungsbei- spieles erläutert werden.According to the invention, this object is achieved in a method of the type mentioned in the introduction in that the helium supplied to the Joule-Thomson stage is removed from the cold side of the cold head of the refrigerator. The advantage of this measure is that the gas flowing to the narrow point of the Joule-Thomson stage flows through the cold head beforehand and is not only pre-cooled in this way, but is also cleaned particularly thoroughly. Contaminants, such as hydrogen, methane, oil vapors or the like, which clog the bottleneck of the Joule-Thomson stage, freeze out in the regenerator of the cold head displacer or are retained therein. Separate cleaning stages are no longer necessary. Separate heat exchangers for precooling the helium with the cooling stage or stages of the refractor can also be dispensed with. Further advantages and details of the invention will be explained with reference to an embodiment shown in the figure.
In der Figur ist ein zweistufiger, nach dem Gifford-McMahon- Prinzip betriebener Refrigerator dargestellt. Er umfaßt den Kaltkopf 1 mit den Gehäuseteilen 2 und 3. Im Gehäuseteil 2 sind die zylindrischen Arbeitsräume 4 und 5 für die beiden Verdränger 6 und 7 untergebracht.The figure shows a two-stage refrigerator operated according to the Gifford-McMahon principle. It comprises the cold head 1 with the housing parts 2 and 3. In the housing part 2, the cylindrical working spaces 4 and 5 for the two displacers 6 and 7 are accommodated.
Der obere Verdränger 6 ist mit einem Antriebskolben 8 ausgerüstet, dessen zugehöriger Zylinder 9 in einer Füh¬ rungsbuchse 10 untergebracht ist, die den Arbeitsraum 4 zum Gehäuseteil 3 hin abschließt. Die Führungsbuchse 10 ist mit den Bohrungen 11, 12 und 13 ausgerüstet. Die Bohrung 11 mündet in den Arbeitsraum 4 und dient der Versorgung dieses Raumes mit Arbeitsgas. Die Bohrung 13 mündet in einer Querbohrung 14, die mit einer Ringnut 15 in der Außenwandung der Führungsbuchse 10 verbunden ist. Zwei weitere Bohrungen 12 sind durch strichpunktierte Linien angedeutet und dienen dem pneumatischen Antrieb des aus den Verdrängern 6 und 7 bestehenden Systems. Die verschiedenen Bohrungen liegen in von der Zeichenebene unterschiedlichen Ebenen, so daß sie einander nicht kreuzen, was durch die Strichelung bezie¬ hungsweise Strichpunktierung angedeutet ist.The upper displacer 6 is equipped with a drive piston 8, the associated cylinder 9 of which is accommodated in a guide bush 10, which closes off the working space 4 from the housing part 3. The guide bush 10 is equipped with the bores 11, 12 and 13. The bore 11 opens into the working space 4 and serves to supply this space with working gas. The bore 13 opens into a transverse bore 14 which is connected to an annular groove 15 in the outer wall of the guide bush 10. Two further bores 12 are indicated by dash-dotted lines and serve to pneumatically drive the system consisting of the displacers 6 and 7. The different bores lie in different planes from the plane of the drawing, so that they do not cross each other, which is indicated by the dashed line or dash-dot line.
Im Gehäuseteil 3 ist der Steuermotor 16 untergebracht, der über die Welle 17 das Steuerventil 18 betätigt. Dieses Steuerventil 18 dient in an sich bekannter Weise der Ver¬ sorgung der verschiedenen Bohrungen mit unter Hochdruck und unter Niederdruck stehendem Arbeitsgas.In the housing part 3, the control motor 16 is housed, which actuates the control valve 18 via the shaft 17. This control valve 18 is used in a manner known per se to supply the various bores with working gas under high pressure and under low pressure.
Die Anschlüsse für das Hochdruck- und das Niederdruckar¬ beitsgas sind mit 19 und 20 bezeichnet. Die Trennebene 21 zwischen den Gehäuseteilen 2 und 3 liegt in Höhe des Steu¬ erventils 18. Sie ist so gewählt, daß nach der Entfernung des oberen Gehäuseteils 3 mit Motor 16 und Ventil 18 oberhalb der Führungsbuchse 10 ein flacher topfförmiger Raum 22 vorhanden ist. In Höhe dieses Raumes 22 ist eine die Wandung des Gehäuseteils 2 durchsetzende Bohrung 23 vorge¬ sehen, die den Raum 22 mit dem Hochdruckanschluß 19 verbin¬ det. Der Niederdruckanschluß 20 ist an die Bohrung 24 im Gehäuseteil 3 angeschlossen, welche in die Ringnut 15 der Führungsbuchse 10 mündet.The connections for the high-pressure and low-pressure working gas are designated 19 and 20. The parting plane 21 between the housing parts 2 and 3 lies at the level of the control valve 18. It is selected so that after the removal of the upper housing part 3 with the motor 16 and valve 18 A flat pot-shaped space 22 is present above the guide bush 10. At the level of this space 22 there is a bore 23 which penetrates the wall of the housing part 2 and connects the space 22 to the high-pressure connection 19. The low pressure connection 20 is connected to the bore 24 in the housing part 3, which opens into the annular groove 15 of the guide bush 10.
Während des Betriebs des dargestellten Refrigerators strömt das unter Hochdruck stehende Arbeitsgas über den Anschluß 19 in die Kammer 22. Von dort aus werden mit Hilfe des Steuer¬ ventils 18 die verschiedenen Bohrungen versorgt. Das Ar¬ beitsgas gelangt nach seiner Entspannung in den Refrigera- torεtufen in die Bohrungen 13, 14 und strömt über die Ringnut 15 und den Niederdruckanschluß 20 ab.During the operation of the refrigerator shown, the high-pressure working gas flows via the connection 19 into the chamber 22. From there, the various bores are supplied with the aid of the control valve 18. After its expansion in the refrigerator stages, the working gas reaches the bores 13, 14 and flows out via the annular groove 15 and the low-pressure connection 20.
Zum Refrigerator gehört auch noch der Kompressor 31, dessen Einlaß über die Leitung 32 mit dem Niederdruckanschluß 20 und dessen Auslaß über die Leitung 33 mit dem Hochdruckan¬ schluß 19 in Verbindung steht.The refrigerator also includes the compressor 31, the inlet of which is connected to the low-pressure connection 20 via the line 32 and the outlet of which is connected to the high-pressure connection 19 via the line 33.
Mit Refrigeratoren dieser Art können im Bereich des kalten Endes (Flansch 34) der zweiten Stufe 5, 7 des Kaltkopfes 1 Temperaturen von etwa 10° Kelvin mit einer Leistung von 1 Watt erzeugt werden.With refrigerators of this type, temperatures of approximately 10 ° Kelvin with an output of 1 watt can be generated in the region of the cold end (flange 34) of the second stage 5, 7 of the cold head 1.
Das dargestellte Ausführungsbeispiel ist außerdem mit der erfindungsgemäßen Joule-Thomson-Stufe 35 ausgerüstet. Diese umfaßt die passive Engstelle 36, die als Düse, Sinterscheibe oder Kapillare ausgebildet sein kann. Um das Arbeitsgas Helium der Engstelle 36 unmittelbar aus dem Kaltkopf 1 zuführen zu können, ist der Flansch 34 der zweiten Kälte¬ stufe mit einer Bohrung 38 versehen, in die der Rohrab¬ schnitt 39 eingelötet ist. Dieser besteht zweckmäßig aus Edelstahl, damit die zweite Kältestufe des Kaltkopfes 1 und die Joule-Thomson-Stufe 35 durch einen Wärmewiderstand voneinander getrennt sind. Das sich in Höhe der Engstelle 36 entspannende und abküh¬ lende Helium strömt in eine Kammer 41. Beim dargestellten Ausführungsbeispiel ist die Kammer 41 mit Metallnetzen 42 gefüllt. Der Werkstoff für die Metallnetze ist zweckmäßig Kupfer oder Silber. Diese Werkstoffe haben bei Temperaturen unter 10 K eine gute Wärmeleitfähigkeit.The illustrated embodiment is also equipped with the Joule-Thomson stage 35 according to the invention. This includes the passive constriction 36, which can be designed as a nozzle, sintered disk or capillary. In order to be able to supply the working gas helium to the constriction 36 directly from the cold head 1, the flange 34 of the second cooling stage is provided with a bore 38 into which the pipe section 39 is soldered. This suitably consists of stainless steel so that the second cold stage of the cold head 1 and the Joule-Thomson stage 35 are separated from one another by a thermal resistance. The helium which relaxes and cools down at the constriction 36 flows into a chamber 41. In the exemplary embodiment shown, the chamber 41 is filled with metal nets 42. The material for the metal networks is expediently copper or silver. These materials have good thermal conductivity at temperatures below 10 K.
Das entspannte Arbeitsgas verläßt die Kammer 41 und strömt über die Leitung 45 dem Einlaß eines Niederdruckkompressors 46 zu. Dieser komprimiert das Arbeitsgas auf den Einlaßdruck des Kompressors 31, so daß der Auslaß des Niederdruckkom¬ pressors über die Leitung 47 mit der Leitung 32 verbunden werden kann.The expanded working gas leaves chamber 41 and flows via line 45 to the inlet of a low-pressure compressor 46. This compresses the working gas to the inlet pressure of the compressor 31, so that the outlet of the low pressure compressor can be connected to the line 32 via the line 47.
Zweckmäßig wird das beschriebene Ausführungsbeispiel mit den folgenden Drücken betrieben: Der Kompressor 31 bringt das Arbeitsgas auf einen Druck von 10 bis 30 bar, vorzugsweise etwa 20 bar. In den Kälterstufen 4, 6 und 5, 7 des Refri¬ gerators erfolgt eine Entspannung des Heliums auf 2 bis 8 bar, vorzugsweise etwa 4 bar. Ein Teil des Heliums des Refrigeratorkreislaufs (ca. 2 %), welches im Bereich des kalten Endes 34 der zweiten Stufe 5, 7 des Refrigerators bereits eine Temperatur von etwa 6 K hat, wird der Engstelle 36 der Joule-Thomson-Stufe zugeführt. Es entspannt sich dort auf einen Druck von 20 bar bis 1 bar, vorzugsweise 0,6 bar. Die Entspannung bewirkt eine weitere Temperaturerniedrigung, und zwar auf etwa 4,2 K. Das entspannte und abgekühlte Helium durchströmt die Kammer 41 mit den Netzen 42. Es verläßt die Kammer 41 über die Leitung 45 und wird dem Niederdruckkompressor 46 zugeführt, der es auf den Nieder¬ druck im Refrigerator-Kreislauf komprimiert.The exemplary embodiment described is expediently operated at the following pressures: The compressor 31 brings the working gas to a pressure of 10 to 30 bar, preferably about 20 bar. In the cold stages 4, 6 and 5, 7 of the refractor, the helium is expanded to 2 to 8 bar, preferably about 4 bar. Part of the helium of the refrigerator circuit (approx. 2%), which already has a temperature of approximately 6 K in the area of the cold end 34 of the second stage 5, 7 of the refrigerator, is fed to the constriction 36 of the Joule-Thomson stage. It relaxes there to a pressure of 20 bar to 1 bar, preferably 0.6 bar. The relaxation causes a further temperature reduction, to about 4.2 K. The relaxed and cooled helium flows through the chamber 41 with the nets 42. It leaves the chamber 41 via the line 45 and is fed to the low-pressure compressor 46, which it on Low pressure compressed in the refrigerator circuit.
Während des Betriebs des beschriebenen Ausführungsbeispiels können im Bereich des Flansches 43 Temperaturen von etwa 4,5 K mit einer Leistung von 10 mW erzeugt werden. Temperaturen dieser Größenordnung sind für die Verflüssigung von Helium oder beim Einsatz von flüssigem Helium erforderlich, bei¬ spielsweise beiDuring operation of the exemplary embodiment described, temperatures of approximately 4.5 K with an output of 10 mW can be generated in the region of the flange 43. Temperatures of this order are for the liquefaction of helium or necessary when using liquid helium, for example at
supraleitenden Spulen, Mikrowellensystemen, Schaltern odersuperconducting coils, microwave systems, switches or
SQUID-Magnetometern.SQUID magnetometers.
Die Anwendung der Erfindung ist bei einstufigen und mehr¬ stufigen Gifford-McMahon-Refrigeratoren oder bei ähnlichen Refrigeratoren möglich. Alte Refrigeratoren, die mit rege¬ nerativen Wärmetauschern arbeiten, können ausgerüstet werden. Wesentlich ist, daß das Arbeitsgas ein oder mehrere Kältestufen durchströmt hat, bevor es der Engstelle der Joule-Thomson-Stufe zugeführt wird. The invention can be used in single-stage and multi-stage Gifford-McMahon refrigerators or in similar refrigerators. Old refrigerators that work with regenerative heat exchangers can be equipped. It is essential that the working gas has passed through one or more cooling stages before it is fed to the bottleneck of the Joule-Thomson stage.

Claims

PATENTANSPRÜCHE PATENT CLAIMS
1. Verfahren zur Erzeugung sehr tiefer Temperaturen durch Entspannen von Helium im Kaltkopf (1) eines Refrigera¬ tors und durch Entspannen von Helium in einer Joule- Thomson-Stufe (35), welche den Kaltkopf (1) des Refri¬ gerators nachgeordnet ist, dadurch gekennzeichnet, daß das der Joule-Thomson-Stufe (35) zugeführte Helium der kalten Seite (34) des Kaltkopfes (1) entnommen wird.1. Method for generating very low temperatures by relaxing helium in the cold head (1) of a refrigerator and by relaxing helium in a Joule-Thomson stage (35) which is arranged downstream of the cold head (1) of the refractor, characterized in that the helium supplied to the Joule-Thomson stage (35) is taken from the cold side (34) of the cold head (1).
2. Verfahren nach Anspruch 1, dadurch gekennzeichnet, daß die Joule-Thomson-Stufe (35) auf der Temperatur der kalten Seite (34) des Kaltkopfes (1) gehalten wird.2. The method according to claim 1, characterized in that the Joule-Thomson stage (35) is kept at the temperature of the cold side (34) of the cold head (1).
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet. daß der Kaltkopf (1) mindestens zwei Kältestufen (4, 6; 5, 7) aufweist, daß die Joule-Thomson-Stufe (35) auf der Temperatur der kältesten Stufe (5, 7) des Kalt¬ kopfes (1) gehalten wird und daß das der Joule-Thom¬ son-Stufe (35) zugeführte Helium der kältesten Stufe (5, 7) des Kaltkopfes (1) entnommen wird. 3. The method according to claim 1 or 2, characterized. that the cold head (1) has at least two cold stages (4, 6; 5, 7), that the Joule-Thomson stage (35) is kept at the temperature of the coldest stage (5, 7) of the cold head (1) and that the helium supplied to the Joule-Thom¬ stage (35) is taken from the coldest stage (5, 7) of the cold head (1).
4. Verfahren nach Anspruch 1, 2 oder 3, dadurch gekenn¬ zeichnet, daß das Helium im Kaltkopf (1) von etwa 10 bis 30 bar, vorzugsweise etwa 20 bar, auf 2 bis 8 bar, vorzugsweise etwa 4 bar, und in der Joule-Thomson-Stufe (35) von 2 bis 8 bar auf 20 mbar bis 1 bar, vorzugs¬ weise etwa 0,6 bar, entspannt wird.4. The method according to claim 1, 2 or 3, characterized gekenn¬ characterized in that the helium in the cold head (1) from about 10 to 30 bar, preferably about 20 bar, to 2 to 8 bar, preferably about 4 bar, and in the Joule-Thomson stage (35) from 2 to 8 bar to 20 mbar to 1 bar, preferably about 0.6 bar, is relaxed.
5. Mit Helium betriebener Refrigerator mit einem Kaltkopf (1) und einer Joule-Thomson-Stufe (35), dadurch ge¬ kennzeichnet, daß die kalte Seite (34) des Kaltkopfes (1) über einen Leitungsabschnitt (39) mit der Joule- Thomson-Stufe (35) in Verbindung steht, so daß Helium aus dem Refrigerator-Kreislauf der Engstelle (36) der Joule-Thomson-Stufe (35) zugeführt werden kann.5. Helium-operated refrigerator with a cold head (1) and a Joule-Thomson stage (35), characterized in that the cold side (34) of the cold head (1) via a line section (39) with the Joule Thomson stage (35) is connected so that helium can be fed from the refrigerator circuit to the bottleneck (36) of the Joule-Thomson stage (35).
6. Refrigerator nach Anspruch 5, dadurch gekennzeichnet, daß der Leitungsabschnitt (39) aus Edelstahl besteht.6. Refrigerator according to claim 5, characterized in that the line section (39) consists of stainless steel.
7. Refrigerator nach Anspruch 5 oder 6, dadurch gekenn¬ zeichnet, daß die Joule-Thomson-Stufe (35) eine sich an die Engstelle (36) anschließende Kammer (41) aufweist.7. Refrigerator according to claim 5 or 6, characterized gekenn¬ characterized in that the Joule-Thomson stage (35) has an adjacent to the constriction (36) chamber (41).
8. Refrigerator nach Anspruch 7, dadurch gekennzeichnet. daß die Kammer (41) mit Metallnetzen (42) gefüllt ist.8. Refrigerator according to claim 7, characterized. that the chamber (41) is filled with metal nets (42).
9. Refrigerator nach einem der Ansprüche 5 bis 8, dadurch gekennzeichnet, daß ein Niederdruckkompressor (46) vorgesehen ist, mit dessen Hilfe das in der Joule- Thomson-Stufe (35) entspannte Helium auf den Nieder¬ druck im Refrigerator-Kreislauf komprimiert wird. 9. Refrigerator according to one of claims 5 to 8, characterized in that a low-pressure compressor (46) is provided, with the help of which in the Joule-Thomson stage (35) relaxed helium is compressed to the low pressure in the refrigerator circuit .
PCT/EP1995/001048 1994-05-28 1995-03-21 Method and device for the production of very low temperatures WO1995033164A1 (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
EP95913147A EP0760926A1 (en) 1994-05-28 1995-03-21 Method and device for the production of very low temperatures
JP8500205A JPH10501055A (en) 1994-05-28 1995-03-21 Method and apparatus for producing ultra-low temperatures

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19944418724 DE4418724A1 (en) 1994-05-28 1994-05-28 Two-stage refrigerator using Gifford-McMahon principle
DEP4418724.6 1994-05-28

Publications (1)

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JP (1) JPH10501055A (en)
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Also Published As

Publication number Publication date
EP0760926A1 (en) 1997-03-12
DE4418724A1 (en) 1995-11-30
JPH10501055A (en) 1998-01-27

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