EP2307823B1 - Refrigerator, and method for producing very low temperature cold - Google Patents

Refrigerator, and method for producing very low temperature cold Download PDF

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Publication number
EP2307823B1
EP2307823B1 EP09740356.2A EP09740356A EP2307823B1 EP 2307823 B1 EP2307823 B1 EP 2307823B1 EP 09740356 A EP09740356 A EP 09740356A EP 2307823 B1 EP2307823 B1 EP 2307823B1
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EP
European Patent Office
Prior art keywords
mixing chamber
mixture
distiller
feed pipe
phase
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EP09740356.2A
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German (de)
French (fr)
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EP2307823A1 (en
Inventor
Alain Benoit
Philippe Camus
Florian Martin
Sébastien TRIQUENEAUX
Gérard VERMEULEN
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Centre National dEtudes Spatiales CNES
Centre National de la Recherche Scientifique CNRS
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Original Assignee
Centre National dEtudes Spatiales CNES
Centre National de la Recherche Scientifique CNRS
Air Liquide SA
LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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    • 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
    • F25B9/12—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using 3He-4He dilution

Definitions

  • the present invention relates to a dilution refrigerator and a method for producing cold at a very low temperature.
  • the invention more particularly relates to a dilution refrigerator for obtaining very low temperatures
  • a dilution refrigerator for obtaining very low temperatures
  • a mixing chamber a first feed pipe having an upstream end connected to a helium source of isotope 3 ( 3 He) and a downstream end connected to the mixing chamber, a second supply pipe having an upstream end connected to a source of helium isotope 4 ( 4 He) and a downstream end connected to the mixing chamber, a conduit of evacuation of the mixture of 3 He- 4 He produced in the mixing chamber from 3 He and 4 He respectively provided by the first and second conduits
  • the exhaust pipe comprising an upstream end connected to the mixing chamber and a downstream end connected to a recovery volume of the fraction of the mixture discharged, the downstream ends of the first and second ducts and the upstream end of the evacuation duct fluidly communicating with a common joint so as to form the mixing chamber, the phase separation between the helium 3 He- 4 He mixtures being controlled by the 3He and 4He fluxes in
  • the 3 He- 4 He mixture can have two phases, a so-called concentrated 3 He-rich phase and a so-called diluted 4 He-rich phase.
  • concentration of 3 He from the concentrated phase increases from 67% to approximately 100% while the concentration of 3 He from the dilute phase decreases from 67% to about 6.6%.
  • a conventional dilution cooler conventionally comprises a box or mixing chamber filled with two liquid helium phases: a dilute phase and a concentrated phase under the thermodynamic conditions described above.
  • the principle of cold production is essentially as follows: a 4 He- 3 He mixture is created in the thermodynamically isolated mixing box in such quantities that there are the two phases described above (a dilute phase and a concentrated phase ). Extracting 3 He from the diluted phase, from 3 He from the concentrated phase will dissolve in the dilute phase to maintain the equilibrium concentration. This dilution process leads to the production of cold.
  • the document FR2626658 describes a dilution cooler system independent of gravity or orientation.
  • three conduits also called capillaries.
  • the three capillaries are connected together at one end to form a junction (mixing chamber).
  • Two capillaries are used respectively for injecting pure 3 He and 4 He mixture to produce a saturated 3 He- 4 He (concentrated phase mixture of dilute phase).
  • the helium mixture is extracted by the third capillary and is recovered or discharged into the space which acts as a "free" pump. Phase separation between liquid helium mixtures is controlled only by 3 He and 4 He flux and capillary forces, and no longer by gravity.
  • the refrigerator has no distiller.
  • An auxiliary distillation unit may be provided to separate, during a dedicated operation, the two constituents of the 3 He- 4 He mixture possibly recovered (for example by means of storage tanks).
  • An object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.
  • the refrigerator according to the invention is essentially characterized in that it comprises a boiler constituting the recovery volume of the mixture, the boiler ensuring the maintenance of the mixture of 3 He and 4 He at the equilibrium liquid-vapor the boiler forming both the source of 3 He and the source of 4 He, the first supply duct comprising a selective pumping member of 3 He in the boiler to feed the mixing chamber in 3 He continuously and in a first closed loop, the second supply conduit comprising a selective pumping member 4 He in the boiler to feed the mixing chamber in 4 He continuously and according to a separate second closed loop.
  • the invention also relates to a process for producing cold at very low temperature, in particular less than 2K and more preferably less than 1 K by a dilution cycle in which a two-phase mixture of the two isotopes 3 He and 4 He is created in a chamber.
  • mixture from liquid 3 He and 4 He introduced separately via respective supply ducts, in which said mixture is extracted via a discharge duct, 3 He from a so-called concentrated phase to pass 3 He in a so-called diluted phase, and thanks to which the frigories generated by the passage of 3 He in the dilute phase are recovered, the separation of the phases of the two-phase mixture being carried out by the control of the flows of pure 3He and 4He introduced separately into the chamber of mixing and capillary forces in the ducts regardless of gravity.
  • the invention may also relate to any alternative device or method comprising any combination of the above or below features.
  • the dilution cooler 1 comprises a mixing chamber 2 formed at the open ends (common junction) of a first 3 He feed 3 conduit, a second 4 He feed 4 feed and a exhaust duct 8 of the mixture 3 He - 4 He.
  • the exhaust duct 8 comprises, from upstream to downstream, two portions: a first portion (reference zone 13) in which the two phases circulate (concentrated and diluted) and a second portion (reference zone 12) in which the mixture circulates monophasic 3 He ⁇ 4 He after complete dilution of the concentrated phase in the diluted phase.
  • This evacuation duct 8 thus serves to evacuate the mixture of 3 He- 4 He produced in the mixing chamber 2 from 3 He and 4 He respectively provided by the first 3 and second 4 ducts.
  • phase separation between the helium 3 He- 4 He mixtures is controlled by the flows of 3 He and 4 He in the conduits 3, 4, 8 and the capillary forces in the conduits 3, 4, 8. that is, phase separation is not dependent on gravity or orientation (according to the same general principle as in FR2626658 ).
  • the refrigerator 1 comprises a boiler evaporator 5 in which there is 3 He- 4 He diluted liquid mixture in equilibrium with the 3 He rich vapor phase.
  • the boiler 5 (“still” in English) is for example a subset of copper and / or stainless steel provided with the required fluid inlets and outlets and constituting a sealed volume of a few cubic centimeters, for example.
  • the volume of the boiler 5 is dimensioned so that the liquid-gas interface is established within said volume, depending on the quantities of He circulating in the system.
  • the upstream end of the first duct 3 is connected to the boiler 5 via a pump 6 and the downstream end of the first duct 3 is connected to the mixing chamber 2.
  • the second supply duct 4 has an upstream end connected to the boiler 5 via a pump 7 and a downstream end connected to the mixing chamber 2.
  • the exhaust duct 8 is connected to the mixing chamber 2 by its upstream end and is connected to the boiler 5 by its downstream end.
  • the apparatus 1 thus forms two closed loops between the boiler 5 and the mixing chamber 2.
  • the apparatus 1 is filled with a saturated 3 He and 4 He mixture so that there is a vapor-liquid interface in the boiler 5 and a concentrated-diluted interface in the mixing chamber 2.
  • the first 3 supply duct feeds the mixing chamber 2 into 3 He from the boiler 5 via a pump member 6 such as a pump.
  • the second supply duct 4 supplies the mixing chamber 2 with 4 He from the boiler 5 via a pump member 7 such as a pump.
  • the pump 6 of the first conduit 3 pumps mainly 3 He (gaseous) because the temperature in the boiler 5 and the concentration of 3He in the boiler 5 are maintained such that the vapor pressure of 3 He is much higher than that of the 4He.
  • This pump 6 may be a mechanical pump or any other equivalent equivalent pumping system placed at room temperature or cryogenic temperature (eg adsorption pump).
  • a cooler 10 provides liquefaction of the pumped 3 He
  • This cooler 10 may for example consist of a Joule-Thomson trigger system operating with He ( 3 He or 4 He) or any cooler to provide a temperature ideally of the order of 1. , 4 to 1.5 K.
  • the 3 He is cooled by the boiler 5 (heat exchange with the first conduit 3).
  • the 3 He can be cooled via a heat exchange between the first duct 3 and the exhaust duct 8 (this exhaust duct 8 possibly also being in heat exchange with the second duct 4).
  • this exhaust duct 8 possibly also being in heat exchange with the second duct 4.
  • Helium isotope 3 ( 3 He) injected in liquid form into the mixing box 2 typically has a temperature of between 10mK and 300mK.
  • the pump 7 of the second duct 4 pumps exclusively liquid 4 He.
  • the liquid pump 7 4 He can be connected to the boiler 5 by means for example of a system 9 called superimposed which acts as a semi-permeable membrane allowing only superfluid 4 He to be pumped.
  • This superficial 9 has an end 19 immersed in the liquid phase of the boiler 5 and a non-submerged and preferably thermally insulated end 29 of the boiler 5.
  • a boundary device 14 may be used to allow the 3 He- 4 He mixture to be confined. liquid in contact with the submerged end 19 of the superficial.
  • This boundary device 14 can operate by capillarity, for example it can consist of a porous medium with a pore size distribution adapted to the desired application. Other systems, for example by electric field, can be envisaged to obtain this confinement between the liquid phase and the gaseous phase.
  • Pump 7 may be a fountain effect pump (thermomechanical pump) or a mechanical pump 4 He or any other suitable equivalent member disposed if necessary downstream of the superleak 9 at ambient or cryogenic temperature (e.g. adsorption pump or cold turbine).
  • the superfluid 4 He pumped in the boiler 5 can be cooled by an external cold source 11 which performs the same function as the cooler 10 of the first duct 3 (cooling to a temperature ideally of the order of 1.4 to 1.5 K ).
  • the two chillers 10 and 11 may moreover constitute only one single and same cooler element. It will be noted that it is thermodynamically feasible to dispense with a cold source (cooler 10 and / or cooler 11 optional (s)), especially if the heat dissipation of the pump 7 of the second duct 4 is sufficiently low.
  • the 4 He can be cooled by the boiler 5 (heat exchange with the second duct 4). Then, the 4 He is cooled via a heat exchange between the second duct 4 and the exhaust duct 8 (this exhaust duct 8 possibly being also in heat exchange with the first duct 3). There is thus a heat exchange zone 12 of the liquid 3 He injected with the monophasic 3 He - 4 He mixture and then a heat exchange zone 13 of the liquid 3 He injected with the 3 He - 4 He biphasic mixture.
  • the isotope helium 4 ( 4 He) injected in liquid form into the mixing chamber 2 typically has a temperature of between 10mK and 300mK.
  • Operating temperatures in the mixing chamber 2 are generally in the range of 10mK to 300mK.
  • the concentration of 3 He in the liquid phase of the boiler 5 is preferably of the order of 10%, the temperature in the boiler 5 is preferably about 1.05K.
  • the vapor pressure in the boiler 5 is of the order of 5mb and the concentration of 3 He in the steam close to 95%.
  • the pumping pressure of the pump 6 of the first duct 3 is therefore typically of the order of 5 mb and the discharge pressure is for example greater or of the order of 200mb, which allows to liquefy the 3 He at the temperature 1.4-1.5K.
  • the temperature of the fluids after pumping and first cooling 10, 11 is for example between 1 and 2K.
  • the dilution refrigerator 1 therefore uses a containment system 14 for locating the liquid and vapor phases in the boiler 5.
  • the refrigerator 1 according to the invention thus makes it possible to continuously maintain two distinct streams of isotopes of helium ( 4 He and 3 He) according to two closed loops, without the need for external helium supply.
  • the refrigerator 1 or cryostat obtained makes it possible to produce and preserve with unlimited autonomy a stable temperature of the order of, for example, 0.05K in the mixing chamber 2.
  • the system described above can be mounted on a support that can be rotated in all directions, especially for applications that are not gravity-dependent or subject to a gravity field.

Description

La présente invention concerne un réfrigérateur à dilution et un procédé de production de froid à très basse température.The present invention relates to a dilution refrigerator and a method for producing cold at a very low temperature.

L'invention concerne plus particulièrement un réfrigérateur à dilution pour l'obtention de très basses températures comprenant une chambre de mélange, un premier conduit d'alimentation ayant une extrémité amont reliée à une source d'hélium d'isotope 3 (3He) et une extrémité aval reliée à la chambre de mélange, un second conduit d'alimentation ayant une extrémité amont reliée à une source d'hélium d'isotope 4 (4He) et une extrémité aval reliée à la chambre de mélange, un conduit d'évacuation du mélange de 3He-4He produit dans la chambre de mélange à partir du 3He et du 4He fournis respectivement par les premier et second conduits, le conduit d'évacuation comprenant une extrémité amont reliée à la chambre de mélange et une extrémité aval reliée à un volume de récupération de la fraction du mélange évacué, les extrémités aval des premier et second conduits et l'extrémité amont du conduit d'évacuation communiquant fluidiquement à une jonction commune de façon à former la chambre de mélange, la séparation de phase entre les mélanges d'hélium 3He-4He étant contrôlée par les flux de 3He et 4He dans les conduits et les forces capillaires dans les conduits indépendamment de la gravité.The invention more particularly relates to a dilution refrigerator for obtaining very low temperatures comprising a mixing chamber, a first feed pipe having an upstream end connected to a helium source of isotope 3 ( 3 He) and a downstream end connected to the mixing chamber, a second supply pipe having an upstream end connected to a source of helium isotope 4 ( 4 He) and a downstream end connected to the mixing chamber, a conduit of evacuation of the mixture of 3 He- 4 He produced in the mixing chamber from 3 He and 4 He respectively provided by the first and second conduits, the exhaust pipe comprising an upstream end connected to the mixing chamber and a downstream end connected to a recovery volume of the fraction of the mixture discharged, the downstream ends of the first and second ducts and the upstream end of the evacuation duct fluidly communicating with a common joint so as to form the mixing chamber, the phase separation between the helium 3 He- 4 He mixtures being controlled by the 3He and 4He fluxes in the conduits and the capillary forces in the conduits regardless of the gravity .

Parmi les méthodes d'obtention de très basses températures, une des plus intéressantes fait appel à la dilution de l'isotope 3He dans l'hélium ordinaire 4He.Among the methods for obtaining very low temperatures, one of the most interesting uses the dilution of the 3 He isotope in ordinary helium 4 He.

Au dessous de 0,88K environ le mélange 3He- 4He peut présenter deux phases, une phase riche en 3He dite concentrée et une phase riche en 4He dite diluée. Quand la température décroit de 0,88K à 0K, la concentration en 3He de la phase concentrée croît de 67% à 100% environ tandis que la concentration en 3He de la phase diluée décroît de 67% à 6,6% environ.Below about 0.88K, the 3 He- 4 He mixture can have two phases, a so-called concentrated 3 He-rich phase and a so-called diluted 4 He-rich phase. When the temperature decreases from 0,88K to 0K, the concentration of 3 He from the concentrated phase increases from 67% to approximately 100% while the concentration of 3 He from the dilute phase decreases from 67% to about 6.6%.

Un refroidisseur à dilution traditionnel comprend classiquement une boîte ou chambre de mélange remplie de deux phases d'hélium liquide : une phase diluée et une phase concentrée dans les conditions thermodynamiques décrites ci-dessus. Le principe de production de froid est essentiellement le suivant : on crée dans la boîte de mélange thermodynamiquement isolée un mélange 4He - 3He en quantités telles qu'il y ait les deux phases décrites ci-dessus (une phase diluée et une phase concentrée). En extrayant du 3He de la phase diluée, du 3He issu de la phase concentrée va se dissoudre dans la phase diluée pour maintenir la concentration d'équilibre. Ce processus de dilution conduit à la production de froid.A conventional dilution cooler conventionally comprises a box or mixing chamber filled with two liquid helium phases: a dilute phase and a concentrated phase under the thermodynamic conditions described above. The principle of cold production is essentially as follows: a 4 He- 3 He mixture is created in the thermodynamically isolated mixing box in such quantities that there are the two phases described above (a dilute phase and a concentrated phase ). Extracting 3 He from the diluted phase, from 3 He from the concentrated phase will dissolve in the dilute phase to maintain the equilibrium concentration. This dilution process leads to the production of cold.

Pour qu'un tel dispositif, ou cryostat, fonctionne en continu, il suffit d'introduire dans la boîte de mélange du 3He liquide, éventuellement mélangé d'un peu de 4He, pour compenser les prélèvements.For such a device, or cryostat, to operate continuously, it is sufficient to introduce into the mixing box liquid 3 He, possibly mixed with a little 4 He, to compensate the samples.

Pour permettre le fonctionnement de ces systèmes il est nécessaire de localiser :

  • la phase concentrée (liquide avec 3He majoritaire),
  • la phase de dilution (liquide avec 4He majoritaire) et également
  • la phase vapeur concentrée (3He majoritaire).
To enable the operation of these systems it is necessary to locate:
  • the concentrated phase (liquid with 3 He majority),
  • the dilution phase (liquid with 4 He majority) and also
  • the concentrated vapor phase ( 3 He majority).

Cette localisation des différentes phases est réalisée classiquement par gravité (les phases se séparent du fait de leurs densités différentes). En revanche, lorsque le système est en apesanteur ou dans certaines orientations cette localisation n'est pas possible. Le document EP-A-0327457 décrit un réfrigérateur selon le préambule de la revendication 1.This localization of the different phases is carried out conventionally by gravity (the phases separate because of their different densities). On the other hand, when the system is in zero gravity or in certain orientations this localization is not possible. The document EP-A-0327457 discloses a refrigerator according to the preamble of claim 1.

Le document FR2626658 décrit un système de refroidisseur à dilution indépendant de la gravité ou de l'orientation.The document FR2626658 describes a dilution cooler system independent of gravity or orientation.

Selon ce système, on utilise trois conduits encore appelés capillaires. Les trois capillaires sont connectés ensemble à une extrémité pour former une jonction (chambre de mélange). Deux capillaires sont utilisés respectivement pour injecter du 3He pur et du 4He afin de produire un mélange 3He-4He saturé (mélange de phase concentrée et de phase diluée). Le mélange d'hélium est extrait par le troisième capillaire et est récupéré ou rejeté dans l'espace qui agit comme une pompe "gratuite". La séparation de phase entre les mélanges d'hélium liquides est contrôlée uniquement par le flux de 3He et 4He et les forces capillaires, et non plus par la gravité.According to this system, three conduits, also called capillaries, are used. The three capillaries are connected together at one end to form a junction (mixing chamber). Two capillaries are used respectively for injecting pure 3 He and 4 He mixture to produce a saturated 3 He- 4 He (concentrated phase mixture of dilute phase). The helium mixture is extracted by the third capillary and is recovered or discharged into the space which acts as a "free" pump. Phase separation between liquid helium mixtures is controlled only by 3 He and 4 He flux and capillary forces, and no longer by gravity.

Pour s'affranchir des contraintes de gravité, le réfrigérateur ne comporte pas de distillateur. Une unité de distillation annexe peut être prévue pour séparer, au cours d'une opération dédiée, les deux constituants du mélange 3He - 4He éventuellement récupéré (par exemple au moyen de réserves de stockage).To overcome gravity constraints, the refrigerator has no distiller. An auxiliary distillation unit may be provided to separate, during a dedicated operation, the two constituents of the 3 He- 4 He mixture possibly recovered (for example by means of storage tanks).

La durée de vie de ce système est cependant limitée par les quantités d'isotopes d'hélium prévus pour alimenter la boîte de mélange. De plus, en cas d'utilisation dans des engins spatiaux, le mélange d'hélium extrait est perdu.The life of this system is however limited by the quantities of helium isotopes expected to feed the mixing box. In addition, when used in spacecraft, the mixture of helium extracted is lost.

Un but de la présente invention est de pallier tout ou partie des inconvénients de l'art antérieur relevés ci-dessus.An object of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

A cette fin, le réfrigérateur selon l'invention, par ailleurs conforme à la définition générique qu'en donne le préambule ci-dessus, est essentiellement caractérisé en ce qu'il comporte un bouilleur constituant le volume de récupération du mélange, le bouilleur assurant le maintien du mélange des 3He et 4He à l'équilibre liquide-vapeur le bouilleur formant à la fois la source de 3He et la source de 4He, le premier conduit d'alimentation comprenant un organe de pompage sélectif du 3He dans le bouilleur pour alimenter la chambre de mélange en 3He en continu et selon une première boucle fermée, le second conduit d'alimentation comprenant un organe de pompage sélectif du 4He dans le bouilleur pour alimenter la chambre de mélange en 4He en continu et selon une seconde boucle fermée distincte.To this end, the refrigerator according to the invention, furthermore in accordance with the generic definition given in the preamble above, is essentially characterized in that it comprises a boiler constituting the recovery volume of the mixture, the boiler ensuring the maintenance of the mixture of 3 He and 4 He at the equilibrium liquid-vapor the boiler forming both the source of 3 He and the source of 4 He, the first supply duct comprising a selective pumping member of 3 He in the boiler to feed the mixing chamber in 3 He continuously and in a first closed loop, the second supply conduit comprising a selective pumping member 4 He in the boiler to feed the mixing chamber in 4 He continuously and according to a separate second closed loop.

Par ailleurs, des modes de réalisation de l'invention peuvent comporter l'une ou plusieurs des caractéristiques suivantes :

  • le bouilleur comprend un organe de confinement de la phase liquide par rapport à la phase gazeuse,
  • l'organe de pompage sélectif du 4He comprend une superfuite en liaison fluidique avec la phase liquide confinée par l'organe de confinement et un organe de pompage dont l'aspiration est reliée à la phase liquide via la superfuite,
  • les premier et second conduits et le conduit d'évacuation sont assemblés pour échanger thermiquement entre le bouilleur et la chambre de mélange,
  • l'organe de pompage du premier conduit d'alimentation est une pompe pour pomper du 3He gazeux, telle qu'une pompe mécanique et/ou une ou plusieurs pompes dites à absorbtion,
  • l'extrémité amont du premier conduit d'alimentation et/ou l'organe de pompage du premier conduit d'alimentation débouche dans une zone du bouilleur collectant majoritairement du 3He à partir du mélange 3He-4He à l'équilibre liquide-vapeur,
  • l'organe de pompage du second conduit d'alimentation est une pompe pour pomper du 4He liquide, telle qu'une pompe mécanique et/ou une
Furthermore, embodiments of the invention may include one or more of the following features:
  • the boiler comprises a member for confining the liquid phase with respect to the gaseous phase,
  • the selective pumping member of the 4 He comprises a superflu in fluid connection with the liquid phase confined by the confinement member and a pumping member whose suction is connected to the liquid phase via the superficial,
  • the first and second ducts and the exhaust duct are assembled to heat exchange between the boiler and the mixing chamber,
  • the pumping member of the first supply duct is a pump for pumping 3 He gas, such as a mechanical pump and / or one or more so-called absorption pumps,
  • the upstream end of the first supply duct and / or the pumping member of the first supply duct opens into an area of the boiler collecting mainly 3 He from the liquid-equilibrium 3 He- 4 He mixture. steam,
  • the pumping member of the second feed pipe is a pump for pumping liquid 4 He, such as a mechanical pump and / or

pompe dite fontaine (pompe thermo-mécanique) ou une pompe mécanique pour du 4He,

  • l'extrémité amont du second conduit d'alimentation et/ou l'organe de pompage du second conduit d'alimentation débouche dans une zone du bouilleur collectant majoritairement du 4He à partir du mélange 3He-4He à l'équilibre liquide-vapeur,
  • l'organe de pompage du second conduit d'alimentation ou l'extrémité amont du second conduit d'alimentation débouche dans une zone du bouilleur via un élémentde filtration sélectif de 4He
so-called fountain pump (thermomechanical pump) or a mechanical pump for 4 He,
  • the upstream end of the second supply duct and / or the pumping member of the second supply duct opens into an area of the boiler collecting mainly 4 He from the liquid-equilibrium 3 He- 4 He mixture. steam,
  • the pumping member of the second feed pipe or the upstream end of the second feed pipe opens into an area of the boiler via a selective filtration element of 4 He

L'invention concerne également un procédé de production de froid à très basse température, notamment inférieur à 2K et plus préférentiellement inférieur à 1 K par un cycle de dilution dans lequel on créé un mélange diphasique des deux isotopes 3He et 4He dans une chambre de mélange à partir de 3He et de 4He liquides introduits séparément via des conduits d'alimentation respectifs, dans lequel on extrait dudit mélange, via un conduit d'évacuation, du 3He d'une phase dite concentrée pour faire passer du 3He dans une phase dite diluée, et grâce auquel on récupère les frigories générées par le passage du 3He en phase diluée, la séparation des phases du mélange diphasique étant réalisée par le contrôle des flux de 3He et 4He purs introduits séparément dans la chambre de mélange et des forces capillaires dans les conduits indépendamment de la gravité.The invention also relates to a process for producing cold at very low temperature, in particular less than 2K and more preferably less than 1 K by a dilution cycle in which a two-phase mixture of the two isotopes 3 He and 4 He is created in a chamber. mixture from liquid 3 He and 4 He introduced separately via respective supply ducts, in which said mixture is extracted via a discharge duct, 3 He from a so-called concentrated phase to pass 3 He in a so-called diluted phase, and thanks to which the frigories generated by the passage of 3 He in the dilute phase are recovered, the separation of the phases of the two-phase mixture being carried out by the control of the flows of pure 3He and 4He introduced separately into the chamber of mixing and capillary forces in the ducts regardless of gravity.

Selon une particularité avantageuse le cycle de dilution fonctionne en boucle fermée, le procédé comprenant

  • une première étape de récupération et de séparation des deux isotopes 3He et 4He de la fraction du mélange extrait par un conduit d'évacuation,
  • une seconde étape de ré-introduction dans la chambre de mélange des deux isotopes 3He et 4He séparés lors de la première étape.
According to an advantageous feature, the dilution cycle operates in a closed loop, the process comprising
  • a first step of recovering and separating the two isotopes 3 He and 4 He from the fraction of the mixture extracted by an evacuation pipe,
  • a second step of re-introduction into the mixing chamber of the two isotopes 3 He and 4 He separated during the first step.

Selon d'autres particularités possibles :

  • la première étape de récupération et de séparation des deux isotopes est réalisée dans un bouilleur conformé pour maintenir le mélange 3He-4He à l'équilibre liquide-vapeur,
  • la seconde étape de ré-introduction dans la chambre de mélange des deux isotopes 3He et 4He est réalisée via des organes de pompage respectifs,
  • le mélange des deux isotopes 3He et 4He est maintenu dans la chambre de mélange à une température comprise entre 10mK et 300mK et par exemple 50mK et 300mK,
  • la pression de pompage de l'organe de pompage du premier conduit est comprise entre et 0,1 et 50mb , et de préférence égale à environ 5mbar,
  • le procédé comporte, entre la première étape de récupération et de séparation et la seconde étape de ré-introduction, une étape de refroidissement respectif de l'un ou de chacun des isotopes séparés entre 1 et 2K et de préférence entre 1,4 et 1,5K
  • la température dans le bouilleur et la concentration de 3He dans le bouilleur sont maintenues telles que la pression de vapeur de 3He soit beaucoup plus haute que de celle du 4He,
  • la pression de refoulement de la pompe du premier conduit est comprise entre 50 et 1500mbar et de préférence de l'ordre de 200mb pour une liquéfaction du 3He à une température (refroidissement en sortie de pompe ) de 1,4-1,5K,
  • le procédé utilise un réfrigérateur à dilution comprenant une chambre de mélange, un premier conduit d'alimentation ayant une extrémité amont reliée à une source d'hélium d'isotope 3 (3He) et une extrémité aval reliée à la chambre de mélange, un second conduit d'alimentation ayant une extrémité amont reliée à une source d'hélium d'isotope 4 (4He) et une extrémité aval reliée à la chambre de mélange, un conduit d'évacuation d'une fraction du mélange de 3He-4He produit dans la chambre de mélange à partir des 3He et 4He fournis respectivement par les premier et second conduits, le conduit d'évacuation comprenant une extrémité amont reliée à la chambre de mélange et une extrémité aval reliée à un volume de récupération de la fraction du mélange évacué, les extrémités aval des premier et second conduits et l'extrémité amont du conduit d'évacuation communiquant fluidiquement à une jonction commune de façon à former la chambre de mélange, la séparation de phase entre les mélanges d'hélium étant contrôlée par les flux de 3He et 4He et les forces capillaires dans les conduits au lieu de la gravité, le réfrigérateur comportant en outre un bouilleur constituant le volume de récupération du mélange, le bouilleur assurant le maintien du mélange des 3He et 4He à l'équilibre liquide-vapeur, le bouilleur formant à la fois la source de 3He et la source de 4He, le premier conduit d'alimentation comprenant un organe de pompage sélectif du 3He dans le bouilleur alimentant la chambre de mélange en
According to other possible features:
  • the first step of recovery and separation of the two isotopes is carried out in a boiler shaped to maintain the 3 He- 4 He mixture at the liquid-vapor equilibrium,
  • the second step of re-introduction into the mixing chamber of the two isotopes 3 He and 4 He is carried out via respective pumping members,
  • the mixture of the two isotopes 3 He and 4 He is maintained in the mixing chamber at a temperature of between 10mK and 300mK and for example 50mK and 300mK,
  • the pumping pressure of the pumping member of the first conduit is between 0.1 and 50mb, and preferably equal to about 5mbar,
  • the process comprises, between the first recovery and separation step and the second re-introduction step, a respective cooling step of one or each of the isotopes separated between 1 and 2K and preferably between 1.4 and 1 5K
  • the temperature in the boiler and the concentration of 3 He in the boiler are maintained such that the vapor pressure of 3 He is much higher than that of the 4 He,
  • the discharge pressure of the pump of the first conduit is between 50 and 1500mbar and preferably of the order of 200mb for liquefaction of 3 He at a temperature (cooling at the pump outlet) of 1.4-1.5K,
  • the method uses a dilution refrigerator comprising a mixing chamber, a first feed pipe having an upstream end connected to a source of helium isotope 3 ( 3 He) and a downstream end connected to the mixing chamber, a second feed pipe having an upstream end connected to a source of helium isotope 4 ( 4 He) and a downstream end connected to the mixing chamber, a conduit for discharging a fraction of the mixture of 3 He- 4 He produced in the mixing chamber from 3 He and 4 He respectively provided by the first and second conduits, the exhaust pipe comprising an upstream end connected to the mixing chamber and a downstream end connected to a recovery volume of the fraction of the evacuated mixture, the downstream ends of the first and second conduits and the upstream end of the evacuation conduit fluidly communicating with a common junction so as to form the chamber of m mixture, the phase separation between the helium mixtures being controlled by the 3He and 4He fluxes and the capillary forces in the ducts instead of gravity, the refrigerator further comprising a boiler constituting the recovery volume of the mixture, the boiler ensuring the maintenance of the mixture of 3 He and 4 He in liquid-vapor equilibrium, the boiler forming both the source of 3 He and the source of 4 He, the first supply conduit comprising a selective pumping member of the 3 He in the boiler feeding the mixing chamber in

3He en continu et selon une première boucle fermée, le second conduit d'alimentation comprenant un organe de pompage sélectif du 4He dans le bouilleur alimentant la chambre de mélange en 4He en continu et selon une seconde boucle fermée,

  • la pression dans la pompe du second conduit (pompe à pression fontaine) peut être de plusieurs centaines de mbar afin d'avoir un écoulement turbulent dans les capillaires monophasiques et dans le capillaire entre ladite pompe à pression fontaine et le bouilleur,
  • dans le cas où la pompe 7 du second conduit 4 est une pompe mécanique, la pression de pompage peut être négative,
3 He continuously and in a first closed loop, the second feed duct comprising a selective 4 He pumping member in the boiler supplying the mixing chamber in 4 He continuously and in a second closed loop,
  • the pressure in the pump of the second conduit (fountain pressure pump) can be several hundred mbar in order to have a turbulent flow in the monophasic capillaries and in the capillary between said fountain pressure pump and the boiler,
  • in the case where the pump 7 of the second conduit 4 is a mechanical pump, the pumping pressure can be negative,

L'invention peut concerner également tout dispositif ou procédé alternatif comprenant toute combinaison des caractéristiques ci-dessus ou ci-dessous.The invention may also relate to any alternative device or method comprising any combination of the above or below features.

D'autres particularités et avantages apparaîtront à la lecture de la description ci-après, faite en référence à la figure qui représente de façon schématique et partielle la structure et le fonctionnement d'un réfrigérateur selon un exemple de réalisation possible de l'invention.Other features and advantages will appear on reading the description below, with reference to the figure which shows schematically and partially the structure and operation of a refrigerator according to a possible embodiment of the invention.

Le refroidisseur 1 à dilution comprend une chambre de mélange 2 formée au niveau des extrémités ouvertes (jonction commune) d'un premier conduit 3 d'alimentation en 3He, d'un second conduit 4 d'alimentation en 4He et d'un conduit d'évacuation 8 du mélange 3He - 4He.The dilution cooler 1 comprises a mixing chamber 2 formed at the open ends (common junction) of a first 3 He feed 3 conduit, a second 4 He feed 4 feed and a exhaust duct 8 of the mixture 3 He - 4 He.

Le conduit d'évacuation 8 comprend, d'amont en aval, deux portions : une première portion (zone référence 13) dans laquelle circulent les deux phases (concentrée et diluée) et une seconde portion (zone référence 12) dans laquelle circule le mélange monophasique 3He _ 4He après dilution complète de la phase concentrée dans la phase diluée. Ce conduit d'évacuation 8 sert donc à l'évacuation du mélange de 3He-4He diphasique produit dans la chambre de mélange 2 à partir du 3He et du 4He fournis respectivement par les premier 3 et second 4 conduits.The exhaust duct 8 comprises, from upstream to downstream, two portions: a first portion (reference zone 13) in which the two phases circulate (concentrated and diluted) and a second portion (reference zone 12) in which the mixture circulates monophasic 3 He ~ 4 He after complete dilution of the concentrated phase in the diluted phase. This evacuation duct 8 thus serves to evacuate the mixture of 3 He- 4 He produced in the mixing chamber 2 from 3 He and 4 He respectively provided by the first 3 and second 4 ducts.

La séparation de phase entre les mélanges d'hélium 3He-4He est contrôlée par les flux de 3He et 4He dans les conduits 3, 4, 8 et les forces capillaires dans les conduits 3, 4, 8. C'est-à-dire que la séparation de phase n'est pas dépendante de la gravité ni de l'orientation (selon le même principe général que dans le document FR2626658 ).The phase separation between the helium 3 He- 4 He mixtures is controlled by the flows of 3 He and 4 He in the conduits 3, 4, 8 and the capillary forces in the conduits 3, 4, 8. that is, phase separation is not dependent on gravity or orientation (according to the same general principle as in FR2626658 ).

Le réfrigérateur 1 comprend un évaporateur bouilleur 5 dans lequel on trouve du mélange 3He - 4He liquide dilué en équilibre avec la phase vapeur riche en 3He.The refrigerator 1 comprises a boiler evaporator 5 in which there is 3 He- 4 He diluted liquid mixture in equilibrium with the 3 He rich vapor phase.

Le bouilleur 5 (« still » en anglais) est par exemple un sous ensemble en cuivre et/ou inox muni des entrées et sorties de fluide requises et constituant un volume étanche de quelques centimètres cubes par exemple. Le volume du bouilleur 5 est dimensionné de façon que l'interface liquide-gaz s'établisse à l'intérieur dudit volume, en fonction des quantités de He en circulation dans le système.The boiler 5 ("still" in English) is for example a subset of copper and / or stainless steel provided with the required fluid inlets and outlets and constituting a sealed volume of a few cubic centimeters, for example. The volume of the boiler 5 is dimensioned so that the liquid-gas interface is established within said volume, depending on the quantities of He circulating in the system.

L'extrémité amont du premier 3 conduit est reliée au bouilleur 5 via une pompe 6 et l'extrémité aval du premier 3 conduit est reliée à la chambre 2 de mélange.The upstream end of the first duct 3 is connected to the boiler 5 via a pump 6 and the downstream end of the first duct 3 is connected to the mixing chamber 2.

Le second conduit 4 d'alimentation a une extrémité amont reliée au bouilleur 5 via une pompe 7 et une extrémité aval reliée à la chambre de mélange 2.The second supply duct 4 has an upstream end connected to the boiler 5 via a pump 7 and a downstream end connected to the mixing chamber 2.

Le conduit d'évacuation 8 est relié à la chambre de mélange 2 par son extrémité amont et est relié au bouilleur 5 par son extrémité aval.The exhaust duct 8 is connected to the mixing chamber 2 by its upstream end and is connected to the boiler 5 by its downstream end.

L'appareil 1 forme donc deux boucles fermées entre le bouilleur 5 et la chambre 2 de mélange. L'appareil 1 est rempli d'un mélange 3He et 4He saturé de sorte qu'il y a une interface vapeur-liquide dans le bouilleur 5 et une interface concentré - dilué dans la chambre de mélange 2.The apparatus 1 thus forms two closed loops between the boiler 5 and the mixing chamber 2. The apparatus 1 is filled with a saturated 3 He and 4 He mixture so that there is a vapor-liquid interface in the boiler 5 and a concentrated-diluted interface in the mixing chamber 2.

Le premier 3 conduit d'alimentation alimente la chambre 2 de mélange en 3He à partir du bouilleur 5 via un organe 6 de pompage tel qu'une pompe.The first 3 supply duct feeds the mixing chamber 2 into 3 He from the boiler 5 via a pump member 6 such as a pump.

Le second 4 conduit d'alimentation alimente la chambre 2 de mélange en 4He à partir du bouilleur 5 via un organe 7 de pompage tel qu'une pompe.The second supply duct 4 supplies the mixing chamber 2 with 4 He from the boiler 5 via a pump member 7 such as a pump.

La pompe 6 du premier conduit 3 pompe majoritairement du 3He (gazeux) car la température dans le bouilleur 5 et la concentration de 3He dans le bouilleur 5 sont maintenues telles que la pression de vapeur de 3He soit beaucoup plus haute que de celle du 4He.The pump 6 of the first conduit 3 pumps mainly 3 He (gaseous) because the temperature in the boiler 5 and the concentration of 3He in the boiler 5 are maintained such that the vapor pressure of 3 He is much higher than that of the 4He.

Cette pompe 6 peut être une pompe mécanique ou tout autre système de pompage équivalent approprié placé à température ambiante ou à température cryogénique (par exemple pompe à adsorption). Après son pompage dans le bouilleur 5 le 3He est refroidi avant son introduction dans la chambre 2 de mélange. Par exemple, un refroidisseur 10 assure une liquéfaction du 3He pompé sous forme gazeuse dans le bouilleur 5. Ce refroidisseur10 peut être par exemple composé d'un système à détente Joule-Thomson fonctionnant avec du He (3He ou 4He) ou tout refroidisseur permettant de fournir une température idéalement de l'ordre de 1,4 à 1,5 K. Après ce premier refroidissement 10, le 3He est refroidi par le bouilleur 5 (échange thermique avec le premier conduit 3). Ensuite, le 3He peut être refroidi via un échange thermique entre le premier conduit 3 et le conduit d'évacuation 8 (ce conduit d'évacuation 8 étant éventuellement également en échange thermique avec le second conduit 4). Il y a ainsi une zone 12 d'échange de chaleur du 3He liquide injecté avec le mélange 3He - 4He monophasique puis une zone 13 d'échange de chaleur du 3He liquide injecté avec le mélange 3He - 4He diphasique.This pump 6 may be a mechanical pump or any other equivalent equivalent pumping system placed at room temperature or cryogenic temperature (eg adsorption pump). After being pumped into the boiler, the 3 He is cooled before being introduced into the mixing chamber 2. For example, a cooler 10 provides liquefaction of the pumped 3 He This cooler 10 may for example consist of a Joule-Thomson trigger system operating with He ( 3 He or 4 He) or any cooler to provide a temperature ideally of the order of 1. , 4 to 1.5 K. After this first cooling 10, the 3 He is cooled by the boiler 5 (heat exchange with the first conduit 3). Then, the 3 He can be cooled via a heat exchange between the first duct 3 and the exhaust duct 8 (this exhaust duct 8 possibly also being in heat exchange with the second duct 4). There is thus a heat exchange zone 12 of the liquid 3 He injected with the monophasic 3 He - 4 He mixture and then a heat exchange zone 13 of the liquid 3 He injected with the 3 He - 4 He biphasic mixture.

L'hélium isotope 3 (3He) injecté sous forme liquide dans la boîte 2 de mélange a typiquement une température comprise entre 10mK et 300mK.Helium isotope 3 ( 3 He) injected in liquid form into the mixing box 2 typically has a temperature of between 10mK and 300mK.

La pompe 7 du second conduit 4 pompe exclusivement du 4He liquide. La pompe 7 4He liquide peut être connectée au bouilleur 5 au moyen par exemple d'un système 9 appelé superfuite qui agit comme une membrane semi-perméable permettant seulement au superfluide 4He d'être pompé. Cette superfuite 9 a une extrémité 19 immergée dans la phase liquide du bouilleur 5 et une extrémité 29 non immergée et préférentiellement thermiquement isolée du bouilleur 5. En outre, un dispositif frontière 14 peut être utilisé pour permettre de confiner le mélange 3He - 4He liquide au contact de l'extrémité 19 immergée de la superfuite. Ce dispositif 14 frontière peut fonctionner par capillarité, par exemple il peut être constitué d'un milieu poreux avec une distribution des tailles de pores adaptée à l'application recherchée. D'autres systèmes, par exemple par champ électrique, peuvent être envisagés pour obtenir ce confinement entre la phase liquide et la phase gazeuse.The pump 7 of the second duct 4 pumps exclusively liquid 4 He. The liquid pump 7 4 He can be connected to the boiler 5 by means for example of a system 9 called superimposed which acts as a semi-permeable membrane allowing only superfluid 4 He to be pumped. This superficial 9 has an end 19 immersed in the liquid phase of the boiler 5 and a non-submerged and preferably thermally insulated end 29 of the boiler 5. In addition, a boundary device 14 may be used to allow the 3 He- 4 He mixture to be confined. liquid in contact with the submerged end 19 of the superficial. This boundary device 14 can operate by capillarity, for example it can consist of a porous medium with a pore size distribution adapted to the desired application. Other systems, for example by electric field, can be envisaged to obtain this confinement between the liquid phase and the gaseous phase.

La pompe 7 peut être une pompe à effet fontaine (pompe thermo-mécanique) ou une pompe 4He mécanique ou tout autre organe équivalent approprié disposé le cas échéant en aval de la superfuite 9 à température ambiante ou cryogénique (par exemple pompe à adsorption ou turbine froide).Pump 7 may be a fountain effect pump (thermomechanical pump) or a mechanical pump 4 He or any other suitable equivalent member disposed if necessary downstream of the superleak 9 at ambient or cryogenic temperature (e.g. adsorption pump or cold turbine).

Le superfluide 4He pompé dans le bouilleur 5 peut être refroidi par une source froide extérieure 11 qui remplit la même fonction que le refroidisseur 10 du premier conduit 3 (refroidissement à une température idéalement de l'ordre de 1,4 à 1,5 K). Les deux refroidisseurs 10 et 11 peuvent d'ailleurs ne constituer qu'un seul et même élément refroidisseur. On notera qu'il est thermodynamiquement envisageable de se passer d'une source froide (refroidisseur 10 et/ou refroidisseur 11 facultatif(s)), notamment si la dissipation thermique de la pompe 7 du second conduit 4 est suffisamment faible.The superfluid 4 He pumped in the boiler 5 can be cooled by an external cold source 11 which performs the same function as the cooler 10 of the first duct 3 (cooling to a temperature ideally of the order of 1.4 to 1.5 K ). The two chillers 10 and 11 may moreover constitute only one single and same cooler element. It will be noted that it is thermodynamically feasible to dispense with a cold source (cooler 10 and / or cooler 11 optional (s)), especially if the heat dissipation of the pump 7 of the second duct 4 is sufficiently low.

Après ce premier refroidissement 11, le 4He peut être refroidi par le bouilleur 5 (échange thermique avec le second conduit 4). Ensuite, le 4He est refroidi via un échange thermique entre le second conduit 4 et le conduit d'évacuation 8 (ce conduit d'évacuation 8 étant éventuellement également en échange thermique avec le premier conduit 3). Il y a ainsi une zone 12 d'échange de chaleur du 3He liquide injecté avec le mélange 3He - 4He monophasique puis une zone 13 d'échange de chaleur du 3He liquide injecté avec le mélange 3He - 4He diphasique.After this first cooling 11, the 4 He can be cooled by the boiler 5 (heat exchange with the second duct 4). Then, the 4 He is cooled via a heat exchange between the second duct 4 and the exhaust duct 8 (this exhaust duct 8 possibly being also in heat exchange with the first duct 3). There is thus a heat exchange zone 12 of the liquid 3 He injected with the monophasic 3 He - 4 He mixture and then a heat exchange zone 13 of the liquid 3 He injected with the 3 He - 4 He biphasic mixture.

L'hélium isotope 4 (4He) injecté sous forme liquide dans la chambre 2 de mélange a typiquement une température comprise entre 10mK et 300mK.The isotope helium 4 ( 4 He) injected in liquid form into the mixing chamber 2 typically has a temperature of between 10mK and 300mK.

Les températures de fonctionnement dans la chambre 2 de mélange sont généralement comprises dans la gamme de 10mK à 300mK.Operating temperatures in the mixing chamber 2 are generally in the range of 10mK to 300mK.

Pour que la pompe à pression fontaine 7 du second conduit 4 puisse fonctionner efficacement, la concentration de 3He dans la phase liquide du bouilleur 5 est de préférence de l'ordre de 10%, la température dans le bouilleur 5 est de préférence d'environ 1,05K. En conséquence, la pression de vapeur dans le bouilleur 5 est de l'ordre de 5mb et la concentration en 3He dans la vapeur proche de 95%.In order for the fountain pressure pump 7 of the second duct 4 to operate efficiently, the concentration of 3 He in the liquid phase of the boiler 5 is preferably of the order of 10%, the temperature in the boiler 5 is preferably about 1.05K. As a result, the vapor pressure in the boiler 5 is of the order of 5mb and the concentration of 3 He in the steam close to 95%.

La pression de pompage de la pompe 6 du premier conduit 3 est donc typiquement de l'ordre de 5 mb et la pression de refoulement est par exemple supérieure ou de l'ordre de 200mb, ce qui permet de liquéfier le 3He à la température de 1,4-1,5K.The pumping pressure of the pump 6 of the first duct 3 is therefore typically of the order of 5 mb and the discharge pressure is for example greater or of the order of 200mb, which allows to liquefy the 3 He at the temperature 1.4-1.5K.

La température des fluides après pompage et premier refroidissement 10, 11 est par exemple comprise entre 1 et 2K.The temperature of the fluids after pumping and first cooling 10, 11 is for example between 1 and 2K.

Le réfrigérateur 1 à dilution selon l'invention utilise donc un système 14 de confinement permettant de localiser les phases liquide et vapeur dans le bouilleur 5.The dilution refrigerator 1 according to the invention therefore uses a containment system 14 for locating the liquid and vapor phases in the boiler 5.

Le réfrigérateur 1 selon l'invention permet ainsi de maintenir en continu deux flux distincts d'isotopes de l'hélium (4He et 3He) selon deux boucles fermées, sans nécessiter d'apport d'hélium extérieur.The refrigerator 1 according to the invention thus makes it possible to continuously maintain two distinct streams of isotopes of helium ( 4 He and 3 He) according to two closed loops, without the need for external helium supply.

Le réfrigérateur 1 ou cryostat obtenu permet de produire et conserver avec une autonomie illimitée une température stable de l'ordre par exemple de 0,05K dans la chambre 2 de mélange.The refrigerator 1 or cryostat obtained makes it possible to produce and preserve with unlimited autonomy a stable temperature of the order of, for example, 0.05K in the mixing chamber 2.

Le système décrit ci-dessus peut être monté sur un support orientable dans toutes les directions en vue notamment d'applications hors gravité ou soumises à un champ de gravité.The system described above can be mounted on a support that can be rotated in all directions, especially for applications that are not gravity-dependent or subject to a gravity field.

Claims (15)

  1. Dilution refrigerator for obtaining very low temperatures, comprising a mixing chamber (2), a first feed pipe (3) having an upstream end connected to a source of helium isotope 3 (3He) and a downstream end connected to the mixing chamber (2), a second feed pipe (4) having an upstream end connected to a source of helium isotope 4 (4He) and a downstream end connected to the mixing chamber (2), a pipe (8) for discharging the mixture of 3He-4He produced in the mixing chamber (2) from the 3He and the 4He supplied respectively by the first (3) and second (4) pipes, the discharge pipe (4) comprising an upstream end connected to the mixing chamber (2) and a downstream end connected to a volume (5) for recovering the fraction of the discharged mixture, the downstream ends of the first (3) and second (4) pipes and the upstream end of the discharge pipe (8) communicating fluidically at a common junction so as to form the mixing chamber (2), the phase separation between the helium mixtures 3He-4He being controlled by the flows of 3He and 4He in the pipes (3, 4, 8) and the capillary forces in the pipes independently of gravity, characterised in that it comprises a distiller (5) constituting the volume in which the mixture is recovered, the distiller (5) keeping the mixture (2) of the 3He and 4He at liquid-vapour equilibrium, the distiller (5) forming both the source of 3He and the source of 4He, the first feed pipe (3) comprising a member (6) for selectively pumping 3He into the distiller (5) in order to feed the mixing chamber (2) with 3He continuously and in a first closed loop, the second feed pipe (4) comprising a member (7, 9) for selectively pumping 4He into the distiller (5) in order to feed the mixing chamber (2) with 4He continuously and in a distinct second closed loop.
  2. Refrigerator according to claim 1, characterised in that the distiller (5) comprises a member (14) for containing the liquid phase with respect to the gaseous phase.
  3. Refrigerator according to claim 2, characterised in that the member (7, 9) for selectively pumping the 4He comprises a superleak (9) in fluidic communication (19) with the liquid phase contained by the containment member (14) and a pumping member (7), the intake of which is connected to the liquid phase (29) via the superleak (9).
  4. Refrigerator according to any of claims 1 to 3, characterised in that the first (3) and second (4) pipes and the discharge pipe (8) are assembled in order to exchange heat between the distiller (5) and the mixing container (2).
  5. Refrigerator according to any of claims 1 to 4, characterised in that the pumping member (6) of the first feed pipe (3) is a pump for pumping gaseous 3He in the manner of a mechanical pump and/or one or more absorption pumps.
  6. Refrigerator according to any of claims 1 to 5, characterised in that the upstream end of the first feed pipe (3) and/or the pumping member (6) of the first feed pipe (3) leads into a zone of the distiller (5) that collects predominantly 3He from the 3He-4He mixture at liquid-vapour equilibrium.
  7. Refrigerator according to any of claims 1 to 6, characterised in that the pumping member (7) of the second feed pipe (4) is a pump (P) for pumping liquid 4He in the manner of a mechanical pump and/or a fountain pump (thermomechanical pump) or a superfluid helium mechanical pump.
  8. Refrigerator according to any of claims 1 to 7, characterised in that the upstream end of the second feed pipe (4) and/or the pumping member (7) of the second feed pipe (4) leads into a zone of the distiller (5) that collects predominantly 4He from the 3He-4He mixture at liquid-vapour equilibrium.
  9. Refrigerator according to either claim 7 or claim 8, characterised in that the pumping member (7) of the second feed pipe (4) or the upstream end of the second feed pipe (4) leads into a zone of the distiller (5) via an element (9) for the selective filtration of 4He.
  10. Method for producing cold at a very low temperature, in particular at less than 2 K and more preferably at less than 1 K, using a dilution cycle in which a diphasic mixture of the two isotopes 3He and 4He is created in a mixing chamber (2) from liquid 3He and liquid 4He which are introduced separately via respective feed pipes (3, 4), 3He from a phase known as the concentrated phase being extracted from said mixture, via a discharge pipe (8), in order to cause the 3He to enter a phase known as the diluted phase, and by virtue of which the unit of refrigeration generated by the 3He entering the dilute phase is recovered, the phases of the diphasic mixture being separated by controlling the flows of pure 3He and 4He introduced separately into the mixing chamber (2) and the capillary forces in the pipes (3, 4) independently of gravity, characterised in that the dilution cycle operates in a closed loop, the method comprising:
    - a first step of recovering and separating the two isotopes 3He and 4He from the fraction of the mixture extracted by a discharge pipe (8); and
    - a second step of re-introducing the two isotopes 3He and 4He separated during the first step into the mixing chamber (2).
  11. Method according to claim 10, characterised in that the first step of recovering and separating the two isotopes is carried out in a distiller (5) adapted to keep the 3He-4He mixture (2) at liquid-vapour equilibrium.
  12. Method according to either claim 10 or claim 11, characterised in that the second step of re-introducing the two 3He and 4He isotopes into the mixing chamber (2) is carried out using respective pumping members (6, 7).
  13. Method according to any of claims 10 to 12, characterised in that the mixture of the two isotopes 3He and 4He is kept in the mixing chamber (2) at a temperature of between 10 mK and 300 mK.
  14. Method according to any of claims 10 to 13, characterised in that it comprises, between the first step of recovery and separation and the second step of re-introduction, a step (10, 11) of respectively cooling one or each of the separated isotopes between 1 and 2 K, and preferably between 1.4 and 1.5 K.
  15. Method according to any of claims 10 to 14, characterised in that it uses a dilution refrigerator comprising a mixing chamber (2), a first feed pipe (3) having an upstream end connected to a source of helium isotope 3 (3He) and a downstream end connected to the mixing chamber (2), a second feed pipe (4) having an upstream end connected to a source of helium isotope 4 (4He) and a downstream end connected to the mixing chamber (2), a pipe (8) for discharging a fraction of the mixture of 3He-4He produced in the mixing chamber (2) from the 3He and the 4He supplied respectively by the first (3) and second (4) pipes, the discharge pipe (4) comprising an upstream end connected to the mixing chamber (2) and a downstream end connected to a volume (5) for recovering the fraction of the discharged mixture, the downstream ends of the first (3) and second (4) pipes and the upstream end of the discharge pipe (8) communicating fluidically at a common junction so as to form the mixing chamber (2), the phase separation between the helium mixtures being controlled by the flows of 3He and 4He and the capillary forces in the pipes rather than by gravity, the refrigerator (1) further comprising a distiller (5) constituting the volume in which the mixture is recovered, the distiller (5) keeping the mixture (2) of the 3He and 4He at liquid-vapour equilibrium, the distiller (5) forming both the source of 3He and the source of 4He, the first feed pipe (3) comprising a member (6) for selectively pumping 3He into the distiller (5) feeding the mixing container (2) with 3He continuously and in a first closed loop, the second feed pipe (4) comprising a member (7) for selectively pumping 4He into the distiller (5) feeding the mixing container (2) with 4He continuously and in a second closed loop.
EP09740356.2A 2008-07-31 2009-07-22 Refrigerator, and method for producing very low temperature cold Active EP2307823B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR0855275A FR2934674A1 (en) 2008-07-31 2008-07-31 REFRIGERATOR AND METHOD FOR PRODUCING VERY LOW TEMPERATURE COLD
PCT/FR2009/051468 WO2010012939A1 (en) 2008-07-31 2009-07-22 Refrigerator, and method for producing very low temperature cold

Publications (2)

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EP2307823A1 EP2307823A1 (en) 2011-04-13
EP2307823B1 true EP2307823B1 (en) 2013-05-15

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Application Number Title Priority Date Filing Date
EP09740356.2A Active EP2307823B1 (en) 2008-07-31 2009-07-22 Refrigerator, and method for producing very low temperature cold

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US (1) US20110185766A1 (en)
EP (1) EP2307823B1 (en)
JP (1) JP5313348B2 (en)
CN (1) CN102112824A (en)
FR (1) FR2934674A1 (en)
WO (1) WO2010012939A1 (en)

Families Citing this family (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2493553B (en) * 2011-08-11 2017-09-13 Oxford Instr Nanotechnology Tools Ltd Cryogenic cooling apparatus and method
EP3037746B1 (en) * 2014-12-22 2020-08-12 Sumitomo Heavy Industries, Ltd. Cryocooler and operation method of cryocooler
CN112325498B (en) * 2020-11-06 2022-03-29 格物致寒(苏州)科学仪器有限公司 Dilution refrigeration system and method
CN114754508B (en) * 2022-03-11 2024-03-22 上海铂钺制冷科技有限公司 Very low temperature cold head evaporator capable of inhibiting super-current helium liquid film from climbing against gravity

Family Cites Families (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
NL7902014A (en) * 1979-03-14 1980-09-16 Philips Nv 3HE-4HE DILUTION CHILLER.
NL7902438A (en) * 1979-03-29 1980-10-01 Philips Nv 3HE-4HE CHILLER.
FR2626658B1 (en) * 1988-02-03 1990-07-20 Centre Nat Etd Spatiales PROCESS AND APPARATUS FOR OBTAINING VERY LOW TEMPERATURES
FR2707375B1 (en) * 1993-07-05 1995-09-22 Centre Nat Etd Spatiales Process for obtaining very low temperatures.
GB9406348D0 (en) * 1994-03-30 1994-05-25 Oxford Instr Uk Ltd Sample holding device
JP3644683B2 (en) * 2003-02-28 2005-05-11 大陽日酸株式会社 Dilution refrigerator

Also Published As

Publication number Publication date
EP2307823A1 (en) 2011-04-13
CN102112824A (en) 2011-06-29
JP5313348B2 (en) 2013-10-09
JP2011529561A (en) 2011-12-08
WO2010012939A1 (en) 2010-02-04
FR2934674A1 (en) 2010-02-05
US20110185766A1 (en) 2011-08-04

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