EP0388277B1 - Joule-thomson cooling device - Google Patents

Joule-thomson cooling device Download PDF

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Publication number
EP0388277B1
EP0388277B1 EP90400656A EP90400656A EP0388277B1 EP 0388277 B1 EP0388277 B1 EP 0388277B1 EP 90400656 A EP90400656 A EP 90400656A EP 90400656 A EP90400656 A EP 90400656A EP 0388277 B1 EP0388277 B1 EP 0388277B1
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EP
European Patent Office
Prior art keywords
obturator
pressure
cooler
bellows
chamber
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Expired - Lifetime
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EP90400656A
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German (de)
French (fr)
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EP0388277A3 (en
EP0388277A2 (en
Inventor
Serge Reale
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
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Publication of EP0388277A2 publication Critical patent/EP0388277A2/en
Publication of EP0388277A3 publication Critical patent/EP0388277A3/en
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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
    • F25B9/02—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point using Joule-Thompson effect; using vortex effect
    • 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
    • F25B2309/00—Gas cycle refrigeration machines
    • F25B2309/02—Gas cycle refrigeration machines using the Joule-Thompson effect
    • F25B2309/022—Gas cycle refrigeration machines using the Joule-Thompson effect characterised by the expansion element

Definitions

  • the present invention relates to Joule-Thomson coolers of the type comprising a high-pressure working gas line terminating in an expansion orifice formed in a shutter seat and opening into a low pressure discharge circuit, a shutter adapted to reduce the cross section of the expanded working gas at the end of the cooling of the cooler, and actuating means for moving the shutter from a first position, where the expansion orifice is free, to a second position where this orifice is at least partially concealed, the actuating means comprising a rod connecting the shutter to a bellows in a chamber located in the hot part of the cooler and a bulb actuator including an auxiliary gas capacity disposed in the cold part of the cooler , in heat exchange relation with a zone of the low pressure return circuit of the working gas and connected to the chamber around the bellows.
  • the object of the present invention is to provide a rapidly actuated cooler which is particularly reliable and simple to produce.
  • the bulb actuator comprises a heat exchanger including the capacity located near the shutter seat and connected to the chamber by a capillary, and the volume, nature and pressure of the gas.
  • auxiliary are chosen so as to allow the liquefaction of the gas at a temperature higher than the starting temperature of liquefaction of the working gas and to allow a rapid pressure drop in the chamber around the bellows below the pressure prevailing in the bellows to cause an abrupt movement of the shutter.
  • relatively close temperature is meant a temperature reached at a time very close to the time when the working gas begins to liquefy.
  • the Joule-Thomson cooler shown in Figure 1 is combined with a U-section Dewar 1 comprising an outer casing 2 and a central well 3 open upwards and closed at its lower part by an element 4 to be refrigerated, which is by example an infrared disc-shaped detector.
  • the cooler itself comprises a head 5, a tubular core 6, a winding 7 for circulating working gas, and a two-flow valve 8.
  • This cooler is miniaturized to reduce its thermal inertia, the internal diameter of the well 3 being on the order of 4 to 5 mm.
  • the head 5 forms a cylindrical housing which is extended downwards by a peripheral collar 9 fixed on the upper face of the Dewar.
  • the housing has in its lower face a central opening 10 from which the core 6 leaves, which carries at its lower end a shutter seat 11.
  • the winding 7 comprises a high pressure working gas line 12 whose upstream end passes through the head 5 and is connected to a source 13 of a working gas under high pressure, and which is helically wound between the core 6 and the well 13, in a conventional manner in the art.
  • This winding 7 ends in the vicinity of the lower end of the core 6 and defines between these turns a return path of the working gas after expansion, which opens into the surrounding atmosphere by lights 14 pierced in the flange 9.
  • the pipe 12 ends with a short section 12 ′ fitted into the seat 11 and communicating with an expansion orifice 15 formed in the seat 11.
  • the valve 8 comprises a shutter 16 fixed to the lower end of an actuating rod 17, and a bulb actuator 18.
  • the seat 11 has a transverse bore 110 into which the expansion orifice 15 opens centrally and into which the end of the pipe section 12 'is fitted.
  • the shutter is produced in the form of a conical needle 16 secured to a tubular extension 170 of the rod 17.
  • the end of the transverse bore 110 is provided with a restriction 30 providing a very low permanent leakage rate f (of the order of 5 to 10 times) at the nominal flow rate F of the orifice 15.
  • the restriction can be ensured by a pin 31 threaded with clearance in a section of tube 120 fitted into the bore 110.
  • the leakage rate can be ensured by a flat grinding 32 in the conical end portion of the needle 16, providing a clearance j.
  • the rod 17 extends upwards through the entire core 6 and into the head 5, where it is suspended from a horizontal plate 19.
  • An annular chamber 21 is thus defined in the head 5 around the bellows 20.
  • a capillary tube 22 starting from the chamber 21 crosses the sealed wall of the lower wall of this chamber, crosses radially in leaktight manner an orifice 23 provided at the upper end of the core 6, extends downwards along this core , between the latter and the rod 17, and ends with a small capacity forming a heat exchanger 24 constituted by a small number of turns (3 turns in the example shown) brazed on the internal face of the core 6 and adjacent to the seat 11.
  • the lower end of the capillary 22 is hermetically closed.
  • the bellows 20 is produced, during manufacture, so as to have an elasticity tending to close the shutter 16, this closing force being compensated by the inflation pressure of the auxiliary gas on the active surface of the bellows 20.
  • the stressing force in extension (of the order of 200 grams) is provided by a spring 200 disposed around the bellows 20 between the plate 19 and the bottom of the chamber 21.
  • the spring also makes it possible to increase the closing force, thus helping to increase the closing speed of the shutter, and to obtain variable performance by playing on the inflation pressure of the bulb with different types of condensable gas and / or by positioning the heat exchanger 24 higher or lower in the core 6, or by placing it, outside the core 6, in the circuit low pressure return of the working gas, in the coil 7, which improves the heat exchange between the cryogenic working liquid and the auxiliary gas driving the bulb.
  • the working gas is preferably argon or nitrogen and the auxiliary gas is methane, CO2, ethylene or krypton.
  • the pressure of the working gas is chosen so as to allow the actuator 18 to operate, which will be described below, whatever the temperature of the environment and whatever the pressure drops of the low pressure circuit, which may reach 6 to 8 bars at the end of cooling and lead to the establishment of a similar pressure inside the bellows 20.
  • the pressure of the auxiliary gas compresses the bellows, which lowers the rod 17 until a stop 25 carried by it rests on the lower wall of the chamber 21.
  • the shutter 16 is then lifted off from its seat, over an axial distance of the order of a tenth of a millimeter.
  • the high pressure gas can be considered as flowing freely, after its expansion, in the lower space 26 of the well 3 adjacent to the element 4.
  • a solenoid valve 27 controlling the pipe 12 When the device is cooled, a solenoid valve 27 controlling the pipe 12 is opened.
  • the high pressure gas flows in the pipe 12 and is expanded at a high flow rate as the orifice 15 passes.
  • the expanded gas and, as a result, cooled, rises between the turns of the winding 7 until it is discharged into the surrounding atmosphere through the ports 14, by cooling against the current the high pressure working gas.
  • the temperature of the expanded gas decreases more and more, until the appearance of liquid in the chamber 26.
  • the temperature in chamber 26 is then approximately 120 ° K and is obtained after a cooling time of the order of 1 second. Very shortly before this instant, the temperature passes through the liquefaction or solidification temperature of the auxiliary gas under the inflation pressure of the actuator 18.
  • the small volume of auxiliary gas contained in the exchanger 24 liquefies or solidifies then suddenly, which causes the pressure in the chamber 21 to drop below the pressure prevailing in the chamber 26 and therefore in the bellows, thus releasing the mechanical action of the bellows: the plate 19 therefore rises suddenly and causes the application shutter 16 in its seat, closing the orifice 15 and leaving only a minimal leak rate.
  • the expanded gas flow is thus suddenly reduced to a low value but sufficient to keep the device cold; the pressure drop of the low pressure circuit is reduced by the same amount, and the temperature of the liquid contained in the chamber 26 drops to a value close to the boiling point at atmospheric pressure of the working gas.
  • the gas flow rate is very low, the device can be kept cold for an extended period of time.
  • the seat 11, formed at the end of the rod 17, has a conical shape extending downwards.
  • the section 12 ' is fitted into a conduit 121 extended by a nozzle 122 forming the restriction 30 and communicating through a conduit 150 with the expansion orifice 15 opening into the frustoconical wall of the seat.
  • the shutter 16, formed in the extension of the rod 17 is advantageously shaped as a double truncated cone of the same conicity as the seat 11, the lower part having a smaller thickness so as to provide, in the closed position shown, a peripheral clearance j providing a leakage rate parallel to that of the restriction 30 and limiting the risks of occlusion of the orifice 15.

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  • Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Mechanical Engineering (AREA)
  • Thermal Sciences (AREA)
  • General Engineering & Computer Science (AREA)
  • Separation By Low-Temperature Treatments (AREA)
  • Gas Burners (AREA)
  • Physical Or Chemical Processes And Apparatus (AREA)
  • Photometry And Measurement Of Optical Pulse Characteristics (AREA)
  • Temperature-Responsive Valves (AREA)

Description

La présente invention concerne les refroidisseurs Joule-Thomson du type comprenant une conduite de gaz de travail haute pression se terminant par un orifice de détente formé dans un siège d'obturateur et débouchant dans un circuit d'évacuation basse pression, un obturateur adapté pour réduire la section de passage du gaz de travail détendu en fin de mise en froid du refroidisseur, et des moyens d'actionnement pour déplacer l'obturateur d'une première position, où l'orifice de détente est libre, à une seconde position où cet orifice est au moins partiellement masqué, les moyens d'actionnement comprenant une tige raccordant l'obturateur à un soufflet dans une chambre située dans la partie chaude du refroidisseur et un actionneur à bulbe incluant une capacité de gaz auxiliaire disposée dans la partie froide du refroidisseur, en relation d'échange thermique avec une zone du circuit de retour basse pression du gaz de travail et reliée à la chambre autour du soufflet.The present invention relates to Joule-Thomson coolers of the type comprising a high-pressure working gas line terminating in an expansion orifice formed in a shutter seat and opening into a low pressure discharge circuit, a shutter adapted to reduce the cross section of the expanded working gas at the end of the cooling of the cooler, and actuating means for moving the shutter from a first position, where the expansion orifice is free, to a second position where this orifice is at least partially concealed, the actuating means comprising a rod connecting the shutter to a bellows in a chamber located in the hot part of the cooler and a bulb actuator including an auxiliary gas capacity disposed in the cold part of the cooler , in heat exchange relation with a zone of the low pressure return circuit of the working gas and connected to the chamber around the bellows.

Un refroidisseur de ce type, à actionnement progressif, est décrit dans le document FR-A-2.039.956.A cooler of this type, with progressive actuation, is described in the document FR-A-2,039,956.

Le document EP-A-0.245.164, au nom de la Demanderesse, décrit par ailleurs un refroidisseur à actionnement brusque, avec des moyens d'actionnement électriques.Document EP-A-0,245,164, in the name of the Applicant, moreover describes an abruptly actuated cooler, with electrical actuation means.

La présente invention a pour but de fournir un refroidisseur à actionnement rapide, qui soit particulièrement fiable et simple à réaliser.The object of the present invention is to provide a rapidly actuated cooler which is particularly reliable and simple to produce.

A cet effet, selon l'invention, l'actionneur à bulbe comprend un échangeur de chaleur incluant la capacité située au voisinage du siège d'obturateur et relié à la chambre par un capillaire, et le volume, la nature et la pression du gaz auxiliaire sont choisis de façon à permettre la liquéfaction du gaz à une température supérieure à la température de début de liquéfaction du gaz de travail et à permettre une chute de pression rapide dans la chambre autour du soufflet au-dessous de la pression régnant dans le soufflet pour provoquer un déplacement brusque de l'obturateur.To this end, according to the invention, the bulb actuator comprises a heat exchanger including the capacity located near the shutter seat and connected to the chamber by a capillary, and the volume, nature and pressure of the gas. auxiliary are chosen so as to allow the liquefaction of the gas at a temperature higher than the starting temperature of liquefaction of the working gas and to allow a rapid pressure drop in the chamber around the bellows below the pressure prevailing in the bellows to cause an abrupt movement of the shutter.

Par "température relativement voisine", comme on le comprendra par la suite, on entend une température atteinte à un instant très voisin de l'instant où le gaz de travail commence à se liquéfier.By "relatively close temperature", as will be understood hereinafter, is meant a temperature reached at a time very close to the time when the working gas begins to liquefy.

Des exemples de réalisation de l'invention vont maintenant être décrits en relation avec les dessins annexés, sur lesquels :

  • la figure 1 est une vue schématique en coupe longitudinale d'un refroidisseur Joule-Thomson selon l'invention ;
  • la figure 2 représente schématiquement, à plus grande échelle, l'obturateur du refroidisseur de la Figure 1 ; et
  • la figure 3 est une vue analogue d'une variante d'obturateur.
Exemplary embodiments of the invention will now be described in relation to the appended drawings, in which:
  • Figure 1 is a schematic longitudinal sectional view of a Joule-Thomson cooler according to the invention;
  • Figure 2 shows schematically, on a larger scale, the shutter of the cooler of Figure 1; and
  • Figure 3 is a similar view of a variant shutter.

Le refroidisseur Joule-Thomson représenté à la figure 1 est combiné à un Dewar 1 à section en U comprenant une enveloppe extérieure 2 et un puits central 3 ouvert vers le haut et obturé à sa partie inférieure par un élément 4 à réfrigérer, qui est par exemple un détecteur infra-rouge en forme de disque.The Joule-Thomson cooler shown in Figure 1 is combined with a U-section Dewar 1 comprising an outer casing 2 and a central well 3 open upwards and closed at its lower part by an element 4 to be refrigerated, which is by example an infrared disc-shaped detector.

Le refroidisseur comprend lui-même une tête 5, un noyau tubulaire 6, un bobinage 7 de circulation de gaz de travail, et une vanne à deux débits 8. Ce refroidisseur est miniaturisé pour diminuer son inertie thermique, le diamètre intérieur du puits 3 étant de l'ordre de 4 à 5 mm.The cooler itself comprises a head 5, a tubular core 6, a winding 7 for circulating working gas, and a two-flow valve 8. This cooler is miniaturized to reduce its thermal inertia, the internal diameter of the well 3 being on the order of 4 to 5 mm.

La tête 5 forme un boîtier cylindrique qui est prolongé vers le bas par une collerette périphérique 9 fixée sur la face supérieure du Dewar. Le boîtier présente dans sa face inférieure une ouverture centrale 10 d'où part le noyau 6, lequel porte à son extrémité inférieure un siège d'obturateur 11.The head 5 forms a cylindrical housing which is extended downwards by a peripheral collar 9 fixed on the upper face of the Dewar. The housing has in its lower face a central opening 10 from which the core 6 leaves, which carries at its lower end a shutter seat 11.

Le bobinage 7 comprend une conduite de gaz de travail haute pression 12 dont l'extrémité amont traverse la tête 5 et est reliée à une source 13 d'un gaz de travail sous pression élevée, et qui est bobiné en hélice entre le noyau 6 et le puits 13, d'une manière classique dans la technique. Ce bobinage 7 se termine au voisinage de l'extrémité inférieure du noyau 6 et définit entre ces spires un trajet de retour du gaz de travail après détente, lequel débouche dans l'atmosphère environnante par des lumières 14 perçées dans la collerette 9. La conduite 12 se termine par un court tronçon 12' emmanché dans le siège 11 et communiquant avec un orifice de détente 15 formé dans le siège 11.The winding 7 comprises a high pressure working gas line 12 whose upstream end passes through the head 5 and is connected to a source 13 of a working gas under high pressure, and which is helically wound between the core 6 and the well 13, in a conventional manner in the art. This winding 7 ends in the vicinity of the lower end of the core 6 and defines between these turns a return path of the working gas after expansion, which opens into the surrounding atmosphere by lights 14 pierced in the flange 9. The pipe 12 ends with a short section 12 ′ fitted into the seat 11 and communicating with an expansion orifice 15 formed in the seat 11.

La vanne 8 comprend un obturateur 16 fixé à l'extrémité inferieure d'une tige d'actionnement 17, et un actionneur à bulbe 18.The valve 8 comprises a shutter 16 fixed to the lower end of an actuating rod 17, and a bulb actuator 18.

Dans le mode de réalisation des figures 1 et 2, le siège 11 comporte un alésage transversal 110 dans lequel débouche centralement l'orifice de détente 15 et dans lequel est emmanché l'extrémité du tronçon de conduite 12'. L'obturateur est réalisé sous la forme d'un pointeau conique 16 solidarisé à une extension tubulaire 170 de la tige 17. L'extrêmité de l'alésage transversal 110 est pourvue d'une restriction 30 ménageant un débit de fuite permanent f très inférieur (de l'ordre de 5 à 10 fois) au débit nominal F de l'orifice 15. Comme représenté sur le figure 2, la restriction peut être assurée par une épingle 31 enfilée avec jeu dans un tronçon de tube 120 emmanché dans l'alésage 110. En variante, comme représenté schématiquement sur la figure 2, le débit de fuite peut être assuré par un meulage plan 32 dans la partie d'extrémité conique du pointeau 16, ménageant un jeu j de fuite.In the embodiment of FIGS. 1 and 2, the seat 11 has a transverse bore 110 into which the expansion orifice 15 opens centrally and into which the end of the pipe section 12 'is fitted. The shutter is produced in the form of a conical needle 16 secured to a tubular extension 170 of the rod 17. The end of the transverse bore 110 is provided with a restriction 30 providing a very low permanent leakage rate f (of the order of 5 to 10 times) at the nominal flow rate F of the orifice 15. As shown in FIG. 2, the restriction can be ensured by a pin 31 threaded with clearance in a section of tube 120 fitted into the bore 110. As a variant, as shown diagrammatically on the Figure 2, the leakage rate can be ensured by a flat grinding 32 in the conical end portion of the needle 16, providing a clearance j.

La tige 17 s'étend vers le haut à travers tout le noyau 6 et jusque dans la tête 5, où elle est suspendue à un plateau horizontal 19. Un soufflet métallique 20, typiquement en acier inoxydable, relie à joint étanche la périphérie de ce plateau à celle de l'ouverture 10. Une chambre annulaire 21 est ainsi définie dans la tête 5 autour du soufflet 20.The rod 17 extends upwards through the entire core 6 and into the head 5, where it is suspended from a horizontal plate 19. A metal bellows 20, typically made of stainless steel, connects the periphery of this seal to the seal. tray to that of the opening 10. An annular chamber 21 is thus defined in the head 5 around the bellows 20.

Un tube capillaire 22 partant de la chambre 21 traverse à joint étanche la paroi inférieure de cette chambre, traverse radialement de façon étanche un orifice 23 prévu à l'extrémité supérieure du noyau 6, s'étend vers le bas tout le long de ce noyau, entre celui-ci et la tige 17, et se termine par une petite capacité formant échangeur de chaleur 24 constitué par un petit nombre de spires (3 spires dans l'exemple représenté) brasées sur la face interne du noyau 6 et adjacentes au siège 11. L'extrémité inférieure du capillaire 22 est hermétiquement fermée.A capillary tube 22 starting from the chamber 21 crosses the sealed wall of the lower wall of this chamber, crosses radially in leaktight manner an orifice 23 provided at the upper end of the core 6, extends downwards along this core , between the latter and the rod 17, and ends with a small capacity forming a heat exchanger 24 constituted by a small number of turns (3 turns in the example shown) brazed on the internal face of the core 6 and adjacent to the seat 11. The lower end of the capillary 22 is hermetically closed.

Le volume de l'échangeur de chaleur 24 est très inférieur à celui de la chambre 21, par exemple 2 mm³ pour l'échangeur et de 50 mm³ à 150 mm³ pour la chambre 21. La chambre 21 et le capillaire 22 sont emplis d'un gaz auxiliaire répondant aux conditions suivantes :

  • température de début de liquéfaction supérieure à la température de début de liquéfaction du gaz de travail compte-tenu des pertes de charge du circuit basse pression et relativement voisine de cette température, et point triple relativement voisin de la même température ;
  • température critique inférieure à la température minimale de l'environnement, par exemple inférieure à - 40°C, pour garantir que le gaz auxiliaire reste à l'état gazeux tant que l'appareil n'est pas en froid ;
  • de préférence, absence de toxicité, d'instabilité et de réaction avec l'hélium (ceci pour permettre d'effectuer des tests d'étanchéité en lui mélangeant quelques % d'hélium).
The volume of the heat exchanger 24 is much less than that of the chamber 21, for example 2 mm³ for the exchanger and from 50 mm³ to 150 mm³ for the chamber 21. The chamber 21 and the capillary 22 are filled with an auxiliary gas meeting the following conditions:
  • start temperature of liquefaction higher than start temperature of liquefaction of the working gas taking into account the pressure drops of the low pressure circuit and relatively close to this temperature, and triple point relatively close to the same temperature;
  • critical temperature below the minimum ambient temperature, for example below -40 ° C, to ensure that the auxiliary gas remains in the gaseous state until the appliance is cold;
  • preferably, absence of toxicity, instability and reaction with helium (this in order to make it possible to carry out leak tests by mixing a few% of helium).

Selon un aspect de l'invention, le soufflet 20 est réalisé, en fabrication, de façon à présenter une élasticité tendant à fermer l'obturateur 16, cet effort de fermeture étant compensé par la pression de gonflage du gaz auxiliaire sur la surface active du soufflet 20.According to one aspect of the invention, the bellows 20 is produced, during manufacture, so as to have an elasticity tending to close the shutter 16, this closing force being compensated by the inflation pressure of the auxiliary gas on the active surface of the bellows 20.

Selon une caractéristique particulière de l'invention, pour éviter les problèmes de fluage en vieillissement du matériau de soufflet, l'effort de sollicitation en extension (de l'ordre de 200 grammes) est assuré par un ressort 200 disposé autour du soufflet 20 entre le plateau 19 et le fond de la chambre 21. Le ressort permet d'autre part d'augmenter l'effort de fermeture, en contribuant donc à augmenter la rapidité de fermeture de l'obturateur, et d'obtenir des performances variables en jouant sur la pression de gonflage du bulbe avec différents types de gaz condensables et/ou en positionnant l'échangeur de chaleur 24 plus ou moins haut dans le noyau 6, ou en le disposant, à l'extérieur du noyau 6, dans le circuit de retour basse pression du gaz de travail, dans le bobinage 7, ce qui permet d'améliorer les échanges thermiques entre le liquide cryogénique de travail et le gaz auxiliaire pilotant le bulbe.According to a particular characteristic of the invention, to avoid the problems of creep in aging of the bellows material, the stressing force in extension (of the order of 200 grams) is provided by a spring 200 disposed around the bellows 20 between the plate 19 and the bottom of the chamber 21. The spring also makes it possible to increase the closing force, thus helping to increase the closing speed of the shutter, and to obtain variable performance by playing on the inflation pressure of the bulb with different types of condensable gas and / or by positioning the heat exchanger 24 higher or lower in the core 6, or by placing it, outside the core 6, in the circuit low pressure return of the working gas, in the coil 7, which improves the heat exchange between the cryogenic working liquid and the auxiliary gas driving the bulb.

Le gaz de travail est de préférence de l'argon ou de l'azote et le gaz auxiliaire du méthane, du CO₂, de l'éthylène ou du krypton.The working gas is preferably argon or nitrogen and the auxiliary gas is methane, CO₂, ethylene or krypton.

La pression du gaz de travail est choisie de façon à permettre le fonctionnement de l'actionneur 18, qui sera décrit plus loin, quelle que soit la température de l'environnement et quelles que soient les pertes de charge du circuit basse pression, lesquelles peuvent atteindre 6 à 8 bars en fin de mise en froid et conduisent à l'établissement d'une pression analogue à l'intérieur du soufflet 20. On peut par exemple choisir une pression de gonflage du gaz de travail de l'ordre de 5 à 30 bars absolus, selon la température de début de liquéfaction ou de solidification du gaz de travail.The pressure of the working gas is chosen so as to allow the actuator 18 to operate, which will be described below, whatever the temperature of the environment and whatever the pressure drops of the low pressure circuit, which may reach 6 to 8 bars at the end of cooling and lead to the establishment of a similar pressure inside the bellows 20. One can for example choose an inflation pressure of the working gas of the order of 5 to 30 bar absolute, depending on the temperature at the start of liquefaction or solidification of the working gas.

Au repos, la pression du gaz auxiliaire comprime le soufflet, ce qui fait descendre la tige 17 jusqu'à ce qu'une butée 25 portée par celle-ci s'appuie sur la paroi inférieure de la chambre 21. L'obturateur 16 est alors décollé de son siège, sur une distance axiale de l'ordre du dixième de millimètre. Le gaz haute pression peut être considéré comme s'écoulant librement, après sa détente, dans l'espace inférieur 26 du puits 3 adjacent à l'élément 4.At rest, the pressure of the auxiliary gas compresses the bellows, which lowers the rod 17 until a stop 25 carried by it rests on the lower wall of the chamber 21. The shutter 16 is then lifted off from its seat, over an axial distance of the order of a tenth of a millimeter. The high pressure gas can be considered as flowing freely, after its expansion, in the lower space 26 of the well 3 adjacent to the element 4.

Lors de la mise en froid du dispositif, on ouvre une électrovanne 27 commandant la conduite 12. Le gaz haute pression s'écoule dans la conduite 12 et est détendu à fort débit au passage de l'orifice 15. Le gaz détendu, et, par suite, refroidi, remonte entre les spires du bobinage 7 jusqu'à être évacué dans l'atmosphère environnante à travers les lumières 14, en refroidissant à contre courant le gaz de travail haute pression. Ainsi, la température du gaz détendu décroît de plus en plus, jusqu'à apparition de liquide dans la chambre 26.When the device is cooled, a solenoid valve 27 controlling the pipe 12 is opened. The high pressure gas flows in the pipe 12 and is expanded at a high flow rate as the orifice 15 passes. The expanded gas, and, as a result, cooled, rises between the turns of the winding 7 until it is discharged into the surrounding atmosphere through the ports 14, by cooling against the current the high pressure working gas. Thus, the temperature of the expanded gas decreases more and more, until the appearance of liquid in the chamber 26.

Compte-tenu des pertes de charge du circuit basse pression, la température dans la chambre 26 est alors de 120°K environ et est obtenue après un temps de mise en froid de l'ordre de 1 seconde. Très peu de temps avant cet instant, la température passe par la température de liquéfaction ou de solidification du gaz auxiliaire sous la pression de gonflage de l'actionneur 18. Le faible volume de gaz auxiliaire contenu dans l'échangeur 24 se liquéfie ou se solidifie alors brusquement, ce qui fait chuter la pression dans la chambre 21 au-dessous de la pression régnant dans la chambre 26 et donc dans le soufflet, libérant ainsi l'action mécanique du soufflet : le plateau 19 remonte donc brusquement et provoque l'application de l'obturateur 16 sur son siège, en obturant l'orifice 15 et en ne laissant qu'un débit de fuite minime. Le débit de gaz détendu est ainsi réduit brusquement à une valeur faible mais suffisante pour assurer le maintien en froid du dispositif ; la perte de charge du circuit basse pression est réduite d'autant, et la température du liquide contenu dans la chambre 26 descend jusqu'à une valeur voisine du point d'ébullition à la pression atmosphérique du gaz de travail. De plus, comme le débit de gaz est très faible, le dispositif peut être maintenu en froid pendant une période de temps prolongée.Given the pressure drops in the low pressure circuit, the temperature in chamber 26 is then approximately 120 ° K and is obtained after a cooling time of the order of 1 second. Very shortly before this instant, the temperature passes through the liquefaction or solidification temperature of the auxiliary gas under the inflation pressure of the actuator 18. The small volume of auxiliary gas contained in the exchanger 24 liquefies or solidifies then suddenly, which causes the pressure in the chamber 21 to drop below the pressure prevailing in the chamber 26 and therefore in the bellows, thus releasing the mechanical action of the bellows: the plate 19 therefore rises suddenly and causes the application shutter 16 in its seat, closing the orifice 15 and leaving only a minimal leak rate. The expanded gas flow is thus suddenly reduced to a low value but sufficient to keep the device cold; the pressure drop of the low pressure circuit is reduced by the same amount, and the temperature of the liquid contained in the chamber 26 drops to a value close to the boiling point at atmospheric pressure of the working gas. In addition, since the gas flow rate is very low, the device can be kept cold for an extended period of time.

Il est à noter qu'avant la liquéfaction ou la solidification du gaz auxiliaire, seul un petit volume de ce gaz se refroidit, ce qui n'influence pratiquement pas la pression dans la chambre 21, située en partie chaude, de sorte que l'obturateur 16 reste jusqu'à lors en position de pleine ouverture.It should be noted that before the liquefaction or solidification of the auxiliary gas, only a small volume of this gas cools, which practically does not influence the pressure in the chamber 21, located in the hot part, so that the shutter 16 remains in the fully open position until then.

Le dispositif ainsi décrit permet à la fois :

  • d'obtenir un temps de mise en froid très court, grâce au fort débit de gaz de travail maintenu jusqu'en fin de mise en froid ;
  • d'obtenir une température finale très basse, grâce à la réduction maximale de la perte de change du circuit basse pression après la mise en froid ;
  • d'assurer une réponse de l'actionneur extrêmement rapide et fiable ;
  • d'avoir une très grande autonomie de fonctionnement, grâce au faible débit de gaz de travail maintenu après la mise en froid ;
  • de convenir avec différents gaz de travail, notamment l'argon et l'azote, grâce au choix des propriétés de changements d'état du gaz auxiliaire.
  • d'autre part, la chambre 21, étant située en partie chaude, peut avoir des dimensions relativement grandes, et il en est de même du plateau 19, ce qui permet une plage importante de choix pour les caractéristiques de l'actionneur selon les gaz utilisés.
The device thus described allows both:
  • to obtain a very short cooling time, thanks to the high flow of working gas maintained until the end of cooling;
  • obtain a very low final temperature, thanks to the maximum reduction in the exchange loss of the low pressure circuit after cooling down;
  • ensure an extremely fast and reliable response from the actuator;
  • to have a very long operating autonomy, thanks to the low flow rate of working gas maintained after cooling;
  • to agree with different working gases, in particular argon and nitrogen, thanks to the choice of the properties of changes of state of the auxiliary gas.
  • on the other hand, the chamber 21, being located in the hot part, can have relatively large dimensions, and it is the same for the plate 19, which allows a large range of choice for the characteristics of the actuator according to the gases used.

Dans la variante de la figure 3, le siège 11, formé à l'extrémité de la tige 17, présente une forme conique s'étendant vers le bas. Le tronçon 12' est emmanché dans un conduit 121 prolongé par un embout 122 formant la restriction 30 et communiquant par un conduit 150 avec l'orifice de détente 15 débouchant dans la paroi tronconique du siège. L'obturateur 16, formé dans le prolongement de la tige 17 est avantageusement conformé en double tronc de cône étagé de même conicité que le siège 11, la partie inférieure présentant une épaisseur moindre de façon à ménager, dans la position de fermeture représentée, un jeu périphérique j ménageant un débit de fuite en parallèle à celui de la restriction 30 et limitant les risques d'occlusion de l'orifice 15.In the variant of FIG. 3, the seat 11, formed at the end of the rod 17, has a conical shape extending downwards. The section 12 'is fitted into a conduit 121 extended by a nozzle 122 forming the restriction 30 and communicating through a conduit 150 with the expansion orifice 15 opening into the frustoconical wall of the seat. The shutter 16, formed in the extension of the rod 17 is advantageously shaped as a double truncated cone of the same conicity as the seat 11, the lower part having a smaller thickness so as to provide, in the closed position shown, a peripheral clearance j providing a leakage rate parallel to that of the restriction 30 and limiting the risks of occlusion of the orifice 15.

Claims (9)

  1. A Joule-Thompson cooler comprising a duct for high-pressure working gas (12) ending in a pressure-reduction orifice (15) formed in an obturator seat and opening into a low-pressure exhaust circuit, an obturator (16) designed to reduce the section of the passage for working gas, the pressure of which has been reduced after the cooler has been cooled, and activation means (18) for displacing the obturator from a first position, where the pressure-reduction orifice is open, to a second position where this orifice is at least partly obstructed, the activation means (18) comprising a rod (17) connecting the obturator (16) to a bellows (20) in a chamber (21) located in the warm part of the cooler and a bulb-type activator (18) including a capacity of auxiliary gas disposed in the cool part of the cooler, in a thermal exchange relationship with a zone of the low-pressure return circuit of the working gas and linked to the chamber (21) around the bellows (20),
    characterised in that the bulb-type activator (18) comprises a heat exchanger (24) including the capacity located in the vicinity of the obturator seat and linked to the chamber (21) by a capillary (22), and in that the volume, nature and pressure of the auxiliary gas are chosen so as to allow the liquefaction of the gas at a temperature above the temperature of the start of liquefaction of the working gas and to allow a rapid fall in pressure in the chamber (21) around the bellows (20) to below the pressure prevailing in the bellows (20) in order to cause an abrupt displacement of the obturator (16).
  2. A cooler according to Claim 1, characterised in that the heat exchanger (24) is constituted by an end of the capillary (22) wound into a spiral.
  3. A cooler according to Claim 1 or Claim 2, characterised in that the bellows (20) exerts an elastic stress tending to bring the obturator (16) into its second position.
  4. A cooler according to Claim 3, characterised in that the elastic stress of the bellows (20) is at least partly ensured by a spring (200) disposed inside the chamber (21).
  5. A cooler according to one of Claims 1 to 4, characterised in that the obturator seat (11) and/or the obturator (16) comprises a means (30; 32) establishing the outflow rate of the working gas.
  6. A cooler according to Claim 5, characterised in that the means for establishing the outflow rate is constituted by a duct (120; 122) provided with a restriction (30), in parallel with the pressure-reduction orifice (15).
  7. A cooler according to Claim 5, characterised in that the means for establishing the outflow rate is constituted by a recess (32) in the obturator (16).
  8. A cooler according to one of Claims 1 to 7, characterised in that the obturator is a needle (16).
  9. A cooler according to one of Claims 1 to 7, characterised in that the obturator (16) takes a double frusto-conical form and cooperates with an obturator seat (11) of frusto-conical form.
EP90400656A 1989-03-15 1990-03-13 Joule-thomson cooling device Expired - Lifetime EP0388277B1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8903383A FR2645256B1 (en) 1989-03-15 1989-03-15 JOULE-THOMSON DUAL FLOW COOLER
FR8903383 1989-03-15

Publications (3)

Publication Number Publication Date
EP0388277A2 EP0388277A2 (en) 1990-09-19
EP0388277A3 EP0388277A3 (en) 1990-11-28
EP0388277B1 true EP0388277B1 (en) 1993-08-18

Family

ID=9379704

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90400656A Expired - Lifetime EP0388277B1 (en) 1989-03-15 1990-03-13 Joule-thomson cooling device

Country Status (6)

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US (1) US5003783A (en)
EP (1) EP0388277B1 (en)
DE (1) DE69002783T2 (en)
FR (1) FR2645256B1 (en)
IL (1) IL93708A (en)
NO (1) NO172263C (en)

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Also Published As

Publication number Publication date
NO172263C (en) 1993-06-23
IL93708A0 (en) 1990-12-23
EP0388277A3 (en) 1990-11-28
US5003783A (en) 1991-04-02
IL93708A (en) 1992-12-01
EP0388277A2 (en) 1990-09-19
FR2645256B1 (en) 1994-12-23
DE69002783T2 (en) 1993-12-09
NO901131L (en) 1990-09-17
DE69002783D1 (en) 1993-09-23
NO172263B (en) 1993-03-15
FR2645256A1 (en) 1990-10-05
NO901131D0 (en) 1990-03-12

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