EP0947787B1 - Device for a thermal connection in a cryogenic machine - Google Patents
Device for a thermal connection in a cryogenic machine Download PDFInfo
- Publication number
- EP0947787B1 EP0947787B1 EP99400772A EP99400772A EP0947787B1 EP 0947787 B1 EP0947787 B1 EP 0947787B1 EP 99400772 A EP99400772 A EP 99400772A EP 99400772 A EP99400772 A EP 99400772A EP 0947787 B1 EP0947787 B1 EP 0947787B1
- Authority
- EP
- European Patent Office
- Prior art keywords
- cold finger
- load
- plate
- gap
- enclosure
- Prior art date
- Legal status (The legal status 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 status listed.)
- Expired - Lifetime
Links
- 239000007789 gas Substances 0.000 claims description 21
- 239000007788 liquid Substances 0.000 claims description 12
- 239000011148 porous material Substances 0.000 claims description 7
- 238000005086 pumping Methods 0.000 claims description 6
- 238000009835 boiling Methods 0.000 claims description 5
- 238000009834 vaporization Methods 0.000 claims description 5
- 230000008016 vaporization Effects 0.000 claims description 5
- 238000009833 condensation Methods 0.000 claims description 3
- 230000005494 condensation Effects 0.000 claims description 3
- 239000000203 mixture Substances 0.000 claims description 3
- 239000008188 pellet Substances 0.000 claims description 2
- XKRFYHLGVUSROY-UHFFFAOYSA-N Argon Chemical compound [Ar] XKRFYHLGVUSROY-UHFFFAOYSA-N 0.000 description 4
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- RTAQQCXQSZGOHL-UHFFFAOYSA-N Titanium Chemical compound [Ti] RTAQQCXQSZGOHL-UHFFFAOYSA-N 0.000 description 3
- 238000001816 cooling Methods 0.000 description 3
- 239000000463 material Substances 0.000 description 3
- 210000000056 organ Anatomy 0.000 description 3
- 229910052719 titanium Inorganic materials 0.000 description 3
- 239000010936 titanium Substances 0.000 description 3
- QGZKDVFQNNGYKY-UHFFFAOYSA-N Ammonia Chemical compound N QGZKDVFQNNGYKY-UHFFFAOYSA-N 0.000 description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 2
- 229910052786 argon Inorganic materials 0.000 description 2
- 238000006073 displacement reaction Methods 0.000 description 2
- 238000009413 insulation Methods 0.000 description 2
- 229910052751 metal Inorganic materials 0.000 description 2
- 239000002184 metal Substances 0.000 description 2
- VNWKTOKETHGBQD-UHFFFAOYSA-N methane Chemical compound C VNWKTOKETHGBQD-UHFFFAOYSA-N 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 229910000831 Steel Inorganic materials 0.000 description 1
- 230000001133 acceleration Effects 0.000 description 1
- 239000003570 air Substances 0.000 description 1
- 239000000956 alloy Substances 0.000 description 1
- 229910045601 alloy Inorganic materials 0.000 description 1
- 229910021529 ammonia Inorganic materials 0.000 description 1
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000008878 coupling Effects 0.000 description 1
- 238000010168 coupling process Methods 0.000 description 1
- 238000005859 coupling reaction Methods 0.000 description 1
- 230000007423 decrease Effects 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 239000011152 fibreglass Substances 0.000 description 1
- 239000011521 glass Substances 0.000 description 1
- 230000000977 initiatory effect Effects 0.000 description 1
- 239000011810 insulating material Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 230000005486 microgravity Effects 0.000 description 1
- 230000007935 neutral effect Effects 0.000 description 1
- 239000001301 oxygen Substances 0.000 description 1
- 229910052760 oxygen Inorganic materials 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 238000005057 refrigeration Methods 0.000 description 1
- 230000003014 reinforcing effect Effects 0.000 description 1
- 238000007789 sealing Methods 0.000 description 1
- 239000000377 silicon dioxide Substances 0.000 description 1
- 229910052709 silver Inorganic materials 0.000 description 1
- 239000004332 silver Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000010935 stainless steel Substances 0.000 description 1
- 229910001220 stainless steel Inorganic materials 0.000 description 1
- 239000010959 steel Substances 0.000 description 1
- 229920002994 synthetic fiber Polymers 0.000 description 1
- 230000001052 transient effect Effects 0.000 description 1
- 238000002834 transmittance Methods 0.000 description 1
Images
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
- F25D—REFRIGERATORS; COLD ROOMS; ICE-BOXES; COOLING OR FREEZING APPARATUS NOT OTHERWISE PROVIDED FOR
- F25D19/00—Arrangement or mounting of refrigeration units with respect to devices or objects to be refrigerated, e.g. infrared detectors
- F25D19/006—Thermal coupling structure or interface
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F28—HEAT EXCHANGE IN GENERAL
- F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
- F28D15/00—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies
- F28D15/02—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes
- F28D15/04—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure
- F28D15/043—Heat-exchange apparatus with the intermediate heat-transfer medium in closed tubes passing into or through the conduit walls ; Heat-exchange apparatus employing intermediate heat-transfer medium or bodies in which the medium condenses and evaporates, e.g. heat pipes with tubes having a capillary structure forming loops, e.g. capillary pumped loops
Definitions
- the subject of the present invention is a device comprising a cold finger and a device for thermal bond between the end of the cold finger and a load which should be brought to cryogenic temperature during use.
- the invention finds a particularly application important, although not exclusive, when the machine refrigerator works using the Stirling cycle. However, it can also be used when this machine uses another closed cycle or even a cycle open, for example the Joule Thomson cycle.
- the above machines provide cold to the end, generally consisting of a cover thick, with a cold finger whose base is directly or indirectly in contact with an environment high temperature.
- a very thin-walled tube made of a material having low thermal conductivity, such as steel stainless or titanium.
- the tube being thin, has a very low mechanical strength and very low stiffness. Any force exerted on its end can consequently deforming the cold finger, which has consequences particularly serious when this finger contains a moving element, which is the case with cycle machines Stirling.
- thermal bonding devices consisting of a braid of copper wires having mass and stiffness also weak as possible.
- thermal bonding devices consisting of a braid of copper wires having mass and stiffness also weak as possible.
- a braid of mass and stiffness low to high thermal resistance To assemble the braid on the cover of the cold finger, you must access directly to that finger and to the charge, which is hardly compatible with the realization of a efficient thermal insulation. The fragility of the finger cold makes assembly delicate. So that the braid has the flexibility required it must have a length and a volume important.
- the invention aims in particular to provide a device for thermal link for cryogenic machine responding better than those previously known to the requirements of the practical, in particular by reducing the thermal gradient between the end of the cold finger and the load, avoiding a mechanical connection between the cold finger and the load and allowing a realization of low mass and low volume with fewer assembly constraints.
- the invention notably proposes a device thermal bonding according to claim 1.
- the deformable wall can in particular be constituted by a thin-walled revolution bellows, connecting a base cold finger and the spray plate. He will be in generally preferable effect to avoid direct fixation bellows on the cold finger, the thickness of which is very weak, generally around a tenth of a mm.
- the condensation and vaporization interval will be usually 1 to 10 mm.
- the pumping element by capillarity interposed between the end of the finger and the plate reduces the entrainment of drops forming towards the outside by the gases.
- This pumping element can have various constitutions. It can be made up of a pellet of wicking porous material, occupying the interval between the tip of the cold finger and the plate.
- This tablet may in particular be made of felt of silica, or fiberglass, or even synthetic material, with pores of a few tens of microns diameter.
- the circulation of the liquid from the periphery can also be facilitated by grooves engraved in the end.
- the plate can be extended by a surrounding shirt the end part of the cold finger to avoid training liquid droplets outside the range by gas from vaporization.
- Means of thermal insulation will be provided around enclosure and load to reduce losses thermal. However, such isolation is no longer necessary when the device is intended to operate in space, where there is a deep vacuum.
- the device shown schematically on the Figure 1 comprises a thin tube 10, one end of which is attached to a base 12 belonging to the cryogenic machine and the other end of which is closed by a cover 14, which will generally be thicker than the cylindrical wall of the tube. In general this cover will be attached. he can however be in one piece with the rest of the tube.
- the side wall of the tube is made up of a material with low thermal transmittance, for example stainless steel, titanium or alloy with titanium base.
- cold finger can for example have a diameter of 12 mm, a thickness 0.1 mm and a length of about 60 mm.
- the device shown in Figure 1 is intended for cool a charge contained in a vacuum cryostat.
- This cryostat has an outer casing 16, for example glass with a silver inner side to be reflective.
- This outer envelope 16 is fixed on the base 12 by means not shown and the sealing between the atmosphere and a volume 30 which will be defined later is ensured by an O-ring 18.
- An annular zone 19 of the envelope intended for the fixing and the connection waterproof can be thickened to increase its rigidity.
- the thermal bonding device includes a plate 20 slightly larger in diameter than the cover 14, having a face opposite that of the cover.
- This plate can be made of metal with high conductivity thermal. It is intended to be rigidly connected to the load to be cooled (not shown).
- the plate can be also attached to a partition 24 which can be viewed as the internal envelope of the cryostat. This envelope is fixed mechanically to the outer casing 16 at locations not shown in the figure.
- the internal volume 30 is occupied by gas chosen in depending on the temperature to which the plate 20.
- gas chosen in depending on the temperature to which the plate 20.
- This latter gas has the advantage of being a neutral gas and to have a saturation curve slightly above that of nitrogen, resulting in pressure lower when the temperature of volume 30 is that of the environment on earth, for a quantity of liquid predetermined at 90K in enclosure 30.
- a ballast tank 32 connected to volume 30, so that limit the pressure of the gas contained in volume 30 when the temperature is that of the environment.
- the interval 22 a thickness nominal between 1 and 10 mm. This interval is occupied by a porous organ forming a wick of circulation of liquid by capillarity.
- the thickness of the interval may also be chosen based on the accuracy of positioning that can be expected during assembly and risks of displacement during operation, by example following accelerations or vibrations.
- the plate 20 is advantageously extended by a shirt 34 surrounding the end portion of the cold finger. So that the gas only liquefies against the cover 14, opposite the plate 20, the end part of the wall side of the cold finger can be isolated by a sleeve 36 made of thermal insulating material, over a length of the order of the centimeter.
- This sleeve may in particular be made of material expanded with closed porosity.
- the operation of the device is then as follows, when the assembly shown in the figure is initially at room temperature. Volume 30 is completely filled with gas. When the refrigeration machine works, the gas temperature gradually decreases. Finally she reaches, at the end of the cold finger, the liquefaction temperature. Drops of liquefied gas get form and accumulate against the cover 14 and get bigger, gradually invading the porous organ. If the plate 20 is then at a temperature higher than the boiling point of liquid at prevailing pressure in volume 30, liquid vaporizes on contact with the plate by absorbing heat. Steam recondense on cover 14 and the cycle continues until the temperature of the plate 20 reaches that of the tip of the cold finger.
- Interval 22 can then fill completely with liquid which will vaporize again if the heat transfer by conduction of the insufficient liquid to keep plate 20 below of the boiling point.
- Interval 22 can play the role of the condenser of a heat pipe using the same gas as that present in volume 30 and distributing the cold in the plate 20 and if necessary the wall 24.
- a gas mixture in volume 30 so that the thermal bond can operate in a wider temperature range : for example, we will take a mixture of argon, methane, carbon dioxide and ammonia to cover an area ranging from ambience to - 180 ° C. So whatever the temperature of the working load, at least one of these gases will be in its boiling range, while the others will be in gaseous, liquid or solid form and will only intervene by conduction in the transfer thermal. This possibility can be interesting for applications operating at variable temperatures or to facilitate the transient for cooling the system, allowing the initiation of the thermal link to temperatures higher than the nominal temperature use.
- the thermal gradient between the cover and the plate is very low, the boiling flow is usually 1 to 10 W / cm 2 , even under micro-gravity. No force is exerted by the load on the end of the cold finger, since there is no mechanical connection between the plate and the cold finger, the porous material having no appreciable stiffness.
- the nominal difference between the cover and the plate can be chosen to a value sufficient to compensate for any manufacturing tolerance and any relative displacement. Because the tolerances are high, the cold finger can be easily integrated into a system.
- the plate 20 constitutes only a small excess length, usually less than 10 mm.
- thermal leaks generated by a faulty machine are very small, because stopping this machine will cause the cold finger, vaporization of the liquid and reduction of heat transfers which will only be done in mode conductive through steam, between the cover and the plate.
- means can be designed to pump liquid to the center of the cover.
- We can in particular provide means using capillary forces, such as furrows radials bringing the liquefied gas from the periphery of the cover towards its center.
- the cryostat When the device is intended to operate only in space, therefore under vacuum, the cryostat can be omitted and in this case the bellows 26 simply connects a annular plate tightly fixed to the base 12 (or the base itself) at a bottom extending the plate 20.
- the pumping element 40 constitutes the condenser of a heat pipe 42 for cooling a charge located at distance.
- the porous material 40 does not occupy only the area facing the cold finger 14. It extends into a conduit 42.
- the porous material does not introduce any mechanical coupling, due to its texture.
- the liquid-gas interface 44 is likely to be move through the porous material, depending on the thermal power dissipated in the load. Grooves internal gas return to the condenser part can be arranged inside the duct 42.
Description
La présente invention a pour objet un dispositif comportant un doigt froid et un dispositif de liaison thermique entre l'extrémité du doigt froid et une charge qui doit être portée à une température cryogénique lors de son utilisation.The subject of the present invention is a device comprising a cold finger and a device for thermal bond between the end of the cold finger and a load which should be brought to cryogenic temperature during use.
L'invention trouve une application particulièrement importante, bien que non exclusive, lorsque la machine frigorifique fonctionne en utilisant le cycle de Stirling. Elle est toutefois également utilisable lorsque cette machine utilise un autre cycle fermé ou même un cycle ouvert, par exemple le cycle de Joule Thomson.The invention finds a particularly application important, although not exclusive, when the machine refrigerator works using the Stirling cycle. However, it can also be used when this machine uses another closed cycle or even a cycle open, for example the Joule Thomson cycle.
Les machines ci-dessus fournissent le froid à l'extrémité, généralement constituées par un couvercle épais, d'un doigt froid dont la base est directement ou indirectement en contact avec un environnement à température élevée. Pour réduire les pertes par conduction, on utilise un tube à paroi très mince en un matériau ayant une faible conductibilité thermique, tel que l'acier inoxydable ou le titane. Le tube, étant mince, présente une très faible tenue mécanique et une très faible raideur. Tout effort exercé sur son extrémité peut en conséquence déformer le doigt froid, ce qui a des conséquences particulièrement graves lorsque ce doigt contient un élément mobile, ce qui est le cas des machines à cycle de Stirling.The above machines provide cold to the end, generally consisting of a cover thick, with a cold finger whose base is directly or indirectly in contact with an environment high temperature. To reduce conduction losses, a very thin-walled tube made of a material having low thermal conductivity, such as steel stainless or titanium. The tube, being thin, has a very low mechanical strength and very low stiffness. Any force exerted on its end can consequently deforming the cold finger, which has consequences particularly serious when this finger contains a moving element, which is the case with cycle machines Stirling.
On a en conséquence cherché à réaliser des dispositifs de liaison thermique qui tout à la fois ont une faible résistance thermique et n'appliquent que de faibles efforts sur l'extrémité du doigt froid. On a notamment réalisé des dispositifs de liaison thermique constitués par une tresse en fils de cuivre ayant une masse et une raideur aussi faibles que possible. Cette solution n'est toutefois pas pleinement satisfaisante. Une tresse de masse et de raideur faibles a une résistance thermique élevée. Pour assembler la tresse sur le couvercle du doigt froid, il faut accéder directement à ce doigt et à la charge, ce qui est difficilement compatible avec la réalisation d'une isolation thermique performante. La fragilité du doigt froid rend l'assemblage délicat. Pour que la tresse ait la souplesse requise elle doit avoir une longueur et un volume important.We have therefore sought to make devices thermal bonding which both have low thermal resistance and apply only low forces on the end of the cold finger. We notably carried out thermal bonding devices consisting of a braid of copper wires having mass and stiffness also weak as possible. However, this solution is not fully satisfactory. A braid of mass and stiffness low to high thermal resistance. To assemble the braid on the cover of the cold finger, you must access directly to that finger and to the charge, which is hardly compatible with the realization of a efficient thermal insulation. The fragility of the finger cold makes assembly delicate. So that the braid has the flexibility required it must have a length and a volume important.
L'utilisation d'une tresse thermique a un inconvénient supplémentaire lorsqu'une même charge est refroidie par deux machines, cela pour assurer une redondance. Si une machine est arrêtée, par exemple par suite d'une panne, la fuite thermique parasite par le doigt froid de cette machine, qui reste en liaison thermique avec la charge, s'ajoute à la puissance requise par la charge.The disadvantage of using a thermal braid additional when the same load is cooled by two machines, this to ensure redundancy. If one machine is stopped, for example due to a fault, the parasitic thermal leak by the cold finger of this machine, which remains in thermal connection with the load, adds to the power required by the load.
On connaít également (US-A-4 802 345) un dispositif de liaison thermique entre un doigt froid et une charge, constitué par un jeu étroit dans lequel se trouvent des gaz dont au moins un est incondensable à la température de fonctionnement. Un jeu étroit est indispensable et rend difficile un découplage.Also known (US-A-4 802 345) a device for thermal bond between a cold finger and a load, consisting of a narrow clearance in which there are gases at least one of which is noncondensable at the temperature of operation. Close play is essential and makes difficult decoupling.
Le document US-A-4 178 775 décrit un cryostat pour un détecteur infrarouge refroidi par une machine frigorifique à cycle ouvert. Un papier buvard retient du gaz liquéfié à proximité du détecteur infrarouge. Ce buvard ne joue pas un rôle de pompage, mais seulement de réserve.Document US-A-4,178,775 describes a cryostat for a infrared detector cooled by a refrigerating machine open cycle. Blotting paper traps liquefied gas at near the infrared detector. This blotter doesn't play a pumping role, but only reserve.
L'invention vise notamment à fournir un dispositif de liaison thermique pour machine cryogénique répondant mieux que ceux antérieurement connus aux exigences de la pratique, notamment en réduisant le gradient thermique entre l'extrêmité du doigt froid et la charge, en évitant une liaison mécanique entre le doigt froid et la charge et en permettant une réalisation de faible masse et de faible volume avec moins de contraintes d'assemblage.The invention aims in particular to provide a device for thermal link for cryogenic machine responding better than those previously known to the requirements of the practical, in particular by reducing the thermal gradient between the end of the cold finger and the load, avoiding a mechanical connection between the cold finger and the load and allowing a realization of low mass and low volume with fewer assembly constraints.
Dans ce but l'invention propose notamment un dispositif de liaison thermique suivant la revendication 1. To this end, the invention notably proposes a device thermal bonding according to claim 1.
La paroi déformable peut notamment être constituée par un soufflet de révolution à paroi mince, reliant une embase du doigt froid et la plaque de vaporisation. Il sera en effet généralement préférable d'éviter une fixation directe du soufflet sur le doigt froid, dont l'épaisseur est très faible, généralement de l'ordre du dixième de mm.The deformable wall can in particular be constituted by a thin-walled revolution bellows, connecting a base cold finger and the spray plate. He will be in generally preferable effect to avoid direct fixation bellows on the cold finger, the thickness of which is very weak, generally around a tenth of a mm.
L'intervalle de condensation et de vaporisation sera généralement de 1 à 10 mm. L'élément de pompage par capillarité interposé entre l'extrémité du doigt et la plaque réduit l'entraínement des gouttes en formation vers l'extérieur par les gaz. Cet élément de pompage peut avoir des constitutions diverses. Il peut être constitué par une pastille de matériau poreux formant mèche, occupant l'intervalle compris entre l'extrémité du doigt froid et la plaque. Cette pastille peut notamment être en feutre de silice, ou de fibre de verre, voire même en matière synthétique, avec des pores de quelques dizaines de microns de diamètre. La circulation du liquide à partir de la périphérie peut également être facilitée par des sillons gravés dans l'extrémité.The condensation and vaporization interval will be usually 1 to 10 mm. The pumping element by capillarity interposed between the end of the finger and the plate reduces the entrainment of drops forming towards the outside by the gases. This pumping element can have various constitutions. It can be made up of a pellet of wicking porous material, occupying the interval between the tip of the cold finger and the plate. This tablet may in particular be made of felt of silica, or fiberglass, or even synthetic material, with pores of a few tens of microns diameter. The circulation of the liquid from the periphery can also be facilitated by grooves engraved in the end.
La plaque peut être prolongée par une chemise entourant la partie terminale du doigt froid pour éviter l'entraínement de gouttelettes de liquide en dehors de l'intervalle par le gaz provenant de la vaporisation.The plate can be extended by a surrounding shirt the end part of the cold finger to avoid training liquid droplets outside the range by gas from vaporization.
Des moyens d'isolement thermique, généralement constitués par un vase Dewar, seront prévus autour de l'enceinte et de la charge pour réduire les pertes thermiques. Un tel isolement n'est cependant plus nécessaire lorsque le dispositif est destiné à fonctionner dans l'espace, où règne un vide poussé.Means of thermal insulation, generally made up of a Dewar vase, will be provided around enclosure and load to reduce losses thermal. However, such isolation is no longer necessary when the device is intended to operate in space, where there is a deep vacuum.
Les caractéristiques ci-dessus ainsi que d'autres apparaítront mieux à la lecture de la description qui suit d'un mode particulier de réalisation, donné à titre d'exemple non limitatif. La description se réfère aux dessins qui l'accompagnent. Sur les dessins :
- la figure 1 est une vue en coupe d'un dispositif ;
- la figure 2 montre une variante.
- Figure 1 is a sectional view of a device;
- Figure 2 shows a variant.
Le dispositif représenté schématiquement sur la
figure 1 comprend un tube mince 10 dont une extrémité est
fixée à une embase 12 appartenant à la machine cryogénique
et dont l'autre extrémité est fermée par un couvercle 14,
qui sera généralement plus épais que la paroi cylindrique
du tube. En général ce couvercle sera rapporté. Il peut
cependant être d'une seule pièce avec le reste du tube. En
général, la paroi latérale du tube est constituée en un
matériau à faible coefficient de transmission thermique,
par exemple en acier inoxydable, en titane ou en alliage à
base de titane. Dans le cas d'une machine destinée à
fournir une puissance de réfrigération de 1W à 90K, dans
une ambiance à température maximale de 300K, le doigt froid
peut par exemple avoir un diamètre de 12 mm, une épaisseur
de 0,1 mm et une longueur d'environ 60 mm.The device shown schematically on the
Figure 1 comprises a
Le dispositif représenté sur la figure 1 est destiné à
refroidir une charge contenue dans un cryostat sous vide.
Ce cryostat comporte une enveloppe externe 16, par exemple
en verre ayant une face interne argentée pour être
réfléchissante. Cette enveloppe externe 16 est fixée sur
l'embase 12 par des moyens non représentés et l'étanchéité
entre l'ambiance et un volume 30 qui sera défini plus loin
est assurée par un joint torique 18. Une zone annulaire 19
de l'enveloppe destinée à la fixation et à la liaison
étanche peut être épaissie pour augmenter sa rigidité.The device shown in Figure 1 is intended for
cool a charge contained in a vacuum cryostat.
This cryostat has an
Le dispositif de liaison thermique comprend une plaque
20 de diamètre légèrement supérieur à celui du couvercle
14, présentant une face en regard de celle du couvercle.
Cette plaque peut être en métal à forte conductivité
thermique. Elle est prévue pour être reliée rigidement à la
charge à refroidir (non représentée). La plaque peut être
fixée également à une cloison 24 qu'on peut regarder comme
l'enveloppe interne du cryostat. Cette enveloppe est fixée
mécaniquement à l'enveloppe externe 16 en des emplacements
non indiqués sur la figure. Une paroi souple, représentée
sous forme d'un soufflet métallique 26, relie le fond de
l'enveloppe 24, portée par la plaque 20, à la zone
annulaire 19 de renfort de l'enveloppe externe 16. Elle
sépare ainsi un espace sous vide 28 d'un volume interne 30
entourant le doigt froid 10. Du fait de la souplesse du
soufflet, les pièces 20 et 24, liées mécaniquement à la
charge d'utilisation, restent libres par rapport aux
mouvements relatifs que peuvent avoir par rapport à elles
les pièces 18 et 16 et donc l'extrémité du doigt froid 14.The thermal bonding device includes a
Le volume interne 30 est occupé par du gaz choisi en
fonction de la température à laquelle doit être portée la
plaque 20. On peut notamment utiliser l'azote, l'oxygène,
l'air ou l'argon. Ce dernier gaz présente l'intérêt d'être
un gaz neutre et d'avoir une courbe de saturation
légèrement au-dessus de celle de l'azote, d'où une pression
plus faible lorsque la température du volume 30 est celle
de l'environnement sur terre, pour une quantité de liquide
prédéterminée à 90K dans l'enceinte 30. Souvent on prévoira
un réservoir ballast 32 relié au volume 30, de façon à
limiter la pression du gaz contenu dans le volume 30
lorsque la température est celle de l'environnement.The
On donnera généralement à l'intervalle 22 une épaisseur nominale comprise entre 1 et 10 mm. Cet intervalle est occupé par un organe poreux formant mèche de circulation de liquide par capillarité. L'épaisseur de l'intervalle pourra également être choisie en fonction de la précision de positionnement que l'on peut espérer lors de l'assemblage et des risques de déplacement en fonctionnement, par exemple à la suite d'accélérations ou de vibrations.We will generally give the interval 22 a thickness nominal between 1 and 10 mm. This interval is occupied by a porous organ forming a wick of circulation of liquid by capillarity. The thickness of the interval may also be chosen based on the accuracy of positioning that can be expected during assembly and risks of displacement during operation, by example following accelerations or vibrations.
Pour éviter que des gouttes formées sur le couvercle 14
ne soient entraínées vers une partie plus chaude du doigt
froid, la plaque 20 est avantageusement prolongée par une
chemise 34 entourant la partie terminale du doigt froid.
Pour que le gaz ne se liquéfie que contre le couvercle 14,
en face de la plaque 20, la partie terminale de la paroi
latérale du doigt froid peut être isolée par un manchon 36
en matériau isolant thermique, sur une longueur de l'ordre
du centimètre. Ce manchon peut notamment être en matériau
expansé à porosité fermée.To prevent drops from forming on the
Le fonctionnement du dispositif est alors le suivant,
lorsque l'ensemble représenté sur la figure est
initialement à la température ambiante. Le volume 30 est
entièrement rempli de gaz. Lorsque la machine frigorifique
fonctionne, la température du gaz diminue progressivement.
Finalement elle atteint, à l'extrémité du doigt froid, la
température de liquéfaction. Des gouttes de gaz liquéfié se
forment et s'accumulent contre le couvercle 14 et
grossissent, envahissant progressivement l'organe poreux.
Si la plaque 20 est alors à une température supérieure à la
température d'ébullition du liquide à la pression qui règne
dans le volume 30, du liquide se vaporise au contact de la
plaque en absorbant de la chaleur. De la vapeur se
recondense sur le couvercle 14 et le cycle se poursuit
jusqu'à ce que la température de la plaque 20 atteigne
celle de l'extrémité du doigt froid. L'intervalle 22 peut
se remplir alors complètement de liquide qui se vaporisera
de nouveau si le transfert thermique par conduction du
liquide est insuffisant pour maintenir la plaque 20 en-dessous
de la température d'ébullition. L'intervalle 22
peut jouer le rôle du condenseur d'un caloduc utilisant le
même gaz que celui présent dans le volume 30 et distribuant
le froid dans la plaque 20 et si nécessaire la paroi 24.The operation of the device is then as follows,
when the assembly shown in the figure is
initially at room temperature.
Dans certains cas, on aura intérêt à utiliser un
mélange de gaz dans le volume 30 pour que le lien thermique
puisse fonctionner dans une plus large gamme de température
: par exemple, on prendra un mélange d'argon, de méthane,
de gas carbonique et d'ammoniaque pour couvrir un domaine
allant de l'ambiance à - 180°C. Ainsi, quelle que soit la
température de la charge d'utilisation, l'un au moins de
ces gaz sera dans son domaine d'ébullition, alors que les
autres seront sous forme gazeuse, liquide ou solide et
n'interviendront que par conduction dans le transfert
thermique. Cette possibilité peut être intéressante pour
les applications fonctionnant à des températures variables
ou pour faciliter le transitoire de mise en froid du
système, en permettant l'amorçage du lien thermique à des
températures plus élevées que la température nominale
d'utilisation.In some cases, it would be beneficial to use a
gas mixture in
Le gradient thermique entre le couvercle et la plaque
est très faible, le flux d'ébullition étant habituellement
de 1 à 10 W/cm2, même sous micro-gravité. Aucune force
n'est exercée par la charge sur l'extrémité du doigt froid,
puisqu'il n'y a pas de liaison mécanique entre la plaque et
le doigt froid, le matériau poreux n'ayant pas de rigidité
appréciable. L'écart nominal entre le couvercle et la
plaque peut être choisi à une valeur suffisante pour
compenser toute tolérance de fabrication et tout
déplacement relatif. Du fait que les tolérances sont
élevées, le doigt froid peut être facilement intégré dans
un système. La plaque 20 ne constitue qu'une sur-longueur
faible, habituellement inférieure à 10 mm.The thermal gradient between the cover and the plate is very low, the boiling flow is usually 1 to 10 W / cm 2 , even under micro-gravity. No force is exerted by the load on the end of the cold finger, since there is no mechanical connection between the plate and the cold finger, the porous material having no appreciable stiffness. The nominal difference between the cover and the plate can be chosen to a value sufficient to compensate for any manufacturing tolerance and any relative displacement. Because the tolerances are high, the cold finger can be easily integrated into a system. The
Dans le cas d'un système ayant une charge munie de deux machines pour créer une redondance, les fuites thermiques générées par une machine défaillante sont très réduites, car l'arrêt de cette machine provoque l'échauffement du doigt froid, la vaporisation du liquide et la réduction des transferts thermiques qui ne se feront plus qu'en mode conductif au travers de la vapeur, entre le couvercle et la plaque.In the case of a system with a load provided with two machines to create redundancy, thermal leaks generated by a faulty machine are very small, because stopping this machine will cause the cold finger, vaporization of the liquid and reduction of heat transfers which will only be done in mode conductive through steam, between the cover and the plate.
Comme il a été indiqué plus haut, des moyens peuvent être prévus pour réaliser un pompage de liquide vers le centre du couvercle. On peut en particulier prévoir des moyens utilisant les forces capillaires, tels des sillons radiaux amenant le gaz liquéfié de la périphérie du couvercle vers son centre.As indicated above, means can be designed to pump liquid to the center of the cover. We can in particular provide means using capillary forces, such as furrows radials bringing the liquefied gas from the periphery of the cover towards its center.
Lorsque le dispositif est destiné à fonctionner uniquement
dans l'espace, donc sous vide, le cryostat peut être
omis et dans ce cas le soufflet 26 relie simplement une
plaque annulaire fixée de façon étanche à l'embase 12 (ou
l'embase elle-même) à un fond prolongeant la plaque 20.When the device is intended to operate only
in space, therefore under vacuum, the cryostat can be
omitted and in this case the
Sur la figure 2, où les organes correspondant à ceux de
la figure 1 sont désignés par le même numéro de référence,
l'élément de pompage 40 constitue le condenseur d'un
caloduc 42 de refroidissement d'une charge située à
distance. Pour cela, le matériau poreux 40 n'occupe pas
seulement la zone qui est en face du doigt froid 14. Elle
se prolonge dans un conduit 42. Le matériau poreux
n'introduit aucun couplage mécanique, du fait de sa
texture. L'interface liquide-gaz 44 est susceptible de se
déplacer dans le matériau poreux, en fonction de la
puissance thermique dissipée dans la charge. Des rainures
internes de retour du gaz vers la partie formant condenseur
peuvent être ménagées à l'intérieur du conduit 42.In Figure 2, where the organs corresponding to those of
FIG. 1 are designated by the same reference number,
the pumping
Claims (9)
- Device comprising a cold finger and thermal link device for use between an end, at cryogenic temperature, of the cold finger and a load, comprising a plate (20) confronting said end, for connection with the load, mechanically separate from the end and defining with said end a condensation and vaporization gap occupied by a capillary pumping element and comprising also a deformable wall connected to the plate and defining an enclosure accommodating said gap and surrounding at least the end of the cold finger and the portion of the cold finger which is close to the end, said enclosure being occupied by at least one gas having a condensation temperature selected responsive to the cryogenic temperature to be given to the load.
- Device according to claim 1, characterized in that said pumping element is a pellet of wick-forming porous material occupying the whole gap comprised between the end of the cold finger and the plate (20).
- Device according to claim 1 or 2, characterized in that the plate (20) is extended by a jacket surrounding the end portion of the cold finger for hindering shift of drops of liquid out of said gap due to egress of said gas upon vaporization thereof.
- Device according to claim 3, characterized by a thermally insulating sleeve (36) surrounding the end portion of the cold finger.
- Device according to any one of claims 1 to 4, characterized in that the deformable wall comprises a flexible bellows having a rotational symmetry, and thin wall connecting a base of said cold finger and said plate.
- Device according to any one of Gaims 1 to 5, characterized in that thermally insulating means are positioned around the enclosure and the load.
- Device according to any one of claims 1 to 6, characterized in that said enclosure is occupied by a mixture of a plurality of gases having different boiling temperatures.
- Device according to any one of claims 1 to 7, characterized in that the gap (22) is sized to constitute a condenser of a heat pipe.
- System comprising a load and two cryogenic machines, characterized in that each of said machines comprises a cold finger and a link device connected to the load according to any one of claims 1-8.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| FR9803971A FR2776762B1 (en) | 1998-03-31 | 1998-03-31 | THERMAL BINDING DEVICE FOR CRYOGENIC MACHINE |
| FR9803971 | 1998-03-31 |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| EP0947787A1 EP0947787A1 (en) | 1999-10-06 |
| EP0947787B1 true EP0947787B1 (en) | 2003-09-03 |
Family
ID=9524690
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| EP99400772A Expired - Lifetime EP0947787B1 (en) | 1998-03-31 | 1999-03-30 | Device for a thermal connection in a cryogenic machine |
Country Status (6)
| Country | Link |
|---|---|
| US (1) | US6164077A (en) |
| EP (1) | EP0947787B1 (en) |
| JP (1) | JPH11325629A (en) |
| DE (1) | DE69910877T2 (en) |
| FR (1) | FR2776762B1 (en) |
| IL (1) | IL129271A (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB0125188D0 (en) * | 2001-10-19 | 2001-12-12 | Oxford Magnet Tech | A pulse tube refrigerator sleeve |
| US6915642B2 (en) * | 2002-01-22 | 2005-07-12 | L'Air Liquide-Societe Anonyme à Directoire et Conseil de Surveillance pour l'Etude et l'Exploitation des Procedes Georges Claude | Apparatus and method for extracting cooling power from helium in a cooling system regenerator |
| US7270302B1 (en) * | 2003-04-22 | 2007-09-18 | Lockheed Martin Corporation | Scalable thermal control system for spacecraft mounted instrumentation |
| JP4494027B2 (en) * | 2004-01-26 | 2010-06-30 | 株式会社神戸製鋼所 | Cryogenic equipment |
| JP4290031B2 (en) * | 2004-02-18 | 2009-07-01 | 株式会社サイニクス | Cooling system |
| GB0408425D0 (en) * | 2004-04-15 | 2004-05-19 | Oxford Instr Superconductivity | Cooling apparatus |
| US7415830B2 (en) * | 2005-08-31 | 2008-08-26 | Raytheon Company | Method and system for cryogenic cooling |
| US8069675B2 (en) * | 2006-10-10 | 2011-12-06 | Massachusetts Institute Of Technology | Cryogenic vacuum break thermal coupler |
| US7967256B2 (en) * | 2007-05-08 | 2011-06-28 | Lockheed Martin Corporation | Spacecraft battery thermal management system |
| US20140202172A1 (en) * | 2013-01-22 | 2014-07-24 | Sunpower, Inc. | Cold Finger For Cryocoolers |
| WO2014173809A1 (en) * | 2013-04-24 | 2014-10-30 | Siemens Plc | An assembly comprising a two-stage cryogenic refrigerator and associated mounting arrangement |
| CN105333674B (en) * | 2014-08-08 | 2019-03-05 | 青岛海尔特种电冰柜有限公司 | A kind of refrigerating plant being adaptable to a variety of placed angles |
| DE102014218773B4 (en) | 2014-09-18 | 2020-11-26 | Bruker Biospin Gmbh | Automatic thermal decoupling of a cooling head |
| US11287171B1 (en) | 2017-07-05 | 2022-03-29 | Rigetti & Co, Llc | Heat switches for controlling a flow of heat between thermal stages of a cryostat |
| US11035807B2 (en) * | 2018-03-07 | 2021-06-15 | General Electric Company | Thermal interposer for a cryogenic cooling system |
| CN109945542A (en) * | 2019-03-29 | 2019-06-28 | 中国科学院上海技术物理研究所 | A kind of resistance to stress linear type vascular refrigerator and Dewar coupled structure |
| KR102631379B1 (en) * | 2022-12-09 | 2024-02-01 | 크라이오에이치앤아이(주) | Cryogenic cooling device |
Family Cites Families (11)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR1585049A (en) * | 1968-06-12 | 1970-01-09 | ||
| US3561525A (en) * | 1969-07-02 | 1971-02-09 | Energy Conversion Systemes Inc | Heat pipe condensate return |
| US3894403A (en) * | 1973-06-08 | 1975-07-15 | Air Prod & Chem | Vibration-free refrigeration transfer |
| US4178775A (en) * | 1978-09-18 | 1979-12-18 | Ford Aerospace And Communications Corporation | Cryostat assembly |
| FR2619439B1 (en) * | 1987-08-10 | 1990-01-12 | Air Liquide | METHOD AND DEVICE FOR CRYOGENIC COOLING OF AN OBJECT |
| US4771823A (en) * | 1987-08-20 | 1988-09-20 | The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration | Self-actuating heat switches for redundant refrigeration systems |
| US4802345A (en) * | 1987-12-03 | 1989-02-07 | Hughes Aircraft Company | Non-temperature cycling cryogenic cooler |
| EP0366818A1 (en) * | 1988-11-02 | 1990-05-09 | Leybold Aktiengesellschaft | Cryostatic temperature regulator with a liquid nitrogen bath |
| US5228703A (en) * | 1992-02-18 | 1993-07-20 | Ronald White | Sealing member |
| US5542254A (en) * | 1993-04-15 | 1996-08-06 | Hughes Aircraft Company | Cryogenic cooler |
| FR2752287B1 (en) * | 1996-08-07 | 1998-10-09 | Sagem | CRYOGENIC TEMPERATURE BINDING DEVICE |
-
1998
- 1998-03-31 FR FR9803971A patent/FR2776762B1/en not_active Expired - Fee Related
-
1999
- 1999-03-29 US US09/277,945 patent/US6164077A/en not_active Expired - Fee Related
- 1999-03-30 IL IL12927199A patent/IL129271A/en not_active IP Right Cessation
- 1999-03-30 EP EP99400772A patent/EP0947787B1/en not_active Expired - Lifetime
- 1999-03-30 DE DE69910877T patent/DE69910877T2/en not_active Expired - Fee Related
- 1999-03-31 JP JP11093804A patent/JPH11325629A/en not_active Withdrawn
Also Published As
| Publication number | Publication date |
|---|---|
| FR2776762B1 (en) | 2000-06-16 |
| DE69910877D1 (en) | 2003-10-09 |
| IL129271A0 (en) | 2000-02-17 |
| FR2776762A1 (en) | 1999-10-01 |
| EP0947787A1 (en) | 1999-10-06 |
| IL129271A (en) | 2001-11-25 |
| DE69910877T2 (en) | 2004-09-09 |
| JPH11325629A (en) | 1999-11-26 |
| US6164077A (en) | 2000-12-26 |
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