CRYOGENIC PUMPING SYSTEM AND INNOVATIVE INTEGRATION FOR SUB-KELVIN CRYOGENICS BELOW 1.5K

Abstract

A refrigeration device comprising a first working circuit for circulating a first working fluid, the first working circuit comprising the following elements connected in series by a first network of lines: a first compressor; a cooling unit; a third heat exchanger; a first Joule-Thomson expansion device; a first tank configured to be in heat exchange with an object to be cooled; the refrigeration device also comprising a thermally insulated enclosure and the first working circuit comprises a first pumping member connected to the first network of lines.

Description

FIELD OF THE INVENTION

The present invention relates to the field of refrigeration at very low temperatures and more particularly the field of devices for refrigeration at temperatures close to the kelvin.

BACKGROUND OF THE INVENTION

What is known is a refrigeration device comprising a circuit for circulating a working fluid comprising a compressor for the working fluid, a first heat exchanger comprising a first hot channel in which a first flow of working fluid to be cooled circulates and a first cold channel in which a second flow of working fluid for cooling the first flow circulates, a first Joule-Thomson expansion device and a first separation tank. The refrigeration device also comprises a first network of lines connecting the elements so as to place a first outlet of the compressor, from which first outlet the first working fluid is delivered, in fluidic communication with a first inlet of the first hot channel, a second outlet of the first hot channel in fluidic communication with a second inlet of the first expansion device, a third outlet of the first expansion device in fluidic communication with a third inlet of the first tank, a fourth outlet of the first tank in fluidic communication with a fourth inlet of the first cold channel, and a fifth outlet of the first cold channel in fluidic communication with a fifth inlet of the first compressor, through which fifth inlet the first working fluid is drawn. The refrigeration device also comprises a second heat exchanger which comprises a second hot channel in heat exchange with the first tank. Such a circuit provides cold energy to the second cold channel of the second exchanger. However, the pressure of the working fluid after it has been cooled to very low temperatures (lower than the kelvin) is low, of the order of 0.1 mbar. In order to be able to have a significant cooling power, it is thus necessary to introduce a significant fluid flow rate into the first circuit, and this, at low pressures, requires a significant volumetric pumping capacity and lines dimensioned accordingly. This generally leads to the establishment of a compression device that is highly energy-intensive, resulting in a bulky refrigeration device that is difficult and expensive to utilize.

The aim of the invention is notably to increase the cooling power of a refrigeration device incorporating a Joule-Thomson expansion device.

SUMMARY OF THE INVENTION

To this end, provision is made of a refrigeration device comprising a first working circuit for circulating a first working fluid, the first working circuit comprising the following elements connected in series by a first network of lines:

a first transfer member for the working fluid:

• • a cooling unit comprising a first heat exchanger comprising a first hot channel and a first cold channel that are connected to the first working circuit, the cooling unit also comprising a second heat exchanger comprising a second hot channel connected to the first working circuit and a second cold channel connected to a first cold source;
  • a third heat exchanger comprising a third hot channel and a third cold channel;
  • a first Joule-Thomson expansion device;
  • a first tank configured to be in heat exchange with an object to be cooled.

According to the invention, the device also comprises a thermally insulated enclosure inside which at least some of the elements are located, the first transfer member being situated outside the enclosure. The first working circuit also comprises a first pumping member situated inside the enclosure and connected to the first network of lines.

What is thus obtained is a device capable of circulating a greater quantity of working fluid in the second heat exchanger without modifying the first transfer member, thus allowing improved performance for a given device volume and/or a miniaturization of the refrigeration device.

According to a particular embodiment, the first network of lines is arranged so as to connect:

• • a first outlet of the transfer member, from which first outlet the first working fluid is delivered, to a first inlet of the first hot channel;
  • a second outlet of the first hot channel to a second inlet of the second hot channel;
  • a third outlet of the hot channel to a third inlet of the third hot channel;
  • a fourth outlet of the third hot channel (31) to a fourth inlet of the first expansion device;
  • a fifth outlet of the first expansion device to a fifth inlet of the first tank;
  • a sixth outlet of the first tank to a sixth inlet of the third cold channel;
  • a seventh outlet of the third cold channel to an eighth inlet of the first transfer member, through which eighth inlet the first working fluid is drawn;
  • wherein the first pumping member is situated between the sixth outlet and the eighth inlet.

Advantageously, the first pumping member is connected directly to the eighth inlet.

Also advantageously, the first pumping member is situated downstream of the seventh outlet.

The coldest temperature produced by the device is improved when the device comprises a second Joule-Thomson expansion device and a second tank, the second expansion device comprising a tenth inlet in fluidic communication with the first circuit downstream of the third outlet and a tenth outlet in fluidic communication with an eleventh inlet of the second tank, the second tank comprising an eleventh outlet in fluidic communication with the eighth inlet, the second tank also comprising a first offtake for working fluid in liquid phase in fluidic communication with the first circuit upstream of the third inlet.

The coldest temperature produced by the device is also improved when the device comprises a third Joule-Thomson expansion device, a third tank and a fifth heat exchanger comprising a fifth hot channel and a fifth cold channel, the third expansion device comprising a twelfth inlet in fluidic communication with the first circuit downstream of the third outlet and a twelfth outlet in fluidic communication with a thirteenth inlet of the third tank, the third tank comprising a thirteenth outlet in fluidic communication with the eighth inlet, the third separation tank also comprising a second offtake for working fluid in liquid phase in fluidic communication with a fourteenth inlet of the fifth hot channel, a fourteenth outlet of the fifth hot channel being in fluidic communication with the first circuit upstream of the third inlet, a fifteenth inlet and a fifteenth outlet of the third cold channel being in fluidic communication with the first circuit downstream of the seventh outlet.

Preferably, the refrigeration device comprises a sixth heat exchanger comprising a sixth hot channel and a sixth cold channel, a fourth Joule-Thomson expansion device and a fourth tank, the sixth hot channel comprising a sixteenth inlet in fluidic communication with the first working circuit between the first outlet and the third inlet and the sixth cold channel comprises a sixteenth outlet in fluidic communication with the first working circuit downstream of the fifth outlet.

Advantageously, the first working fluid comprises a volume proportion of helium-4 greater than 99.9%.

Also advantageously, the device comprises a second working circuit for circulating a second working fluid by means of a second transfer member and a second cryogenic pump, the second working circuit comprising at least one first line portion in heat exchange with the first tank.

Preferably, the second transfer member is situated outside the enclosure. A considerable improvement is obtained when the second circuit comprises at least one second line portion in heat exchange with the second tank and/or when the second working circuit also comprises a fifth Joule-Thomson expansion device. The second working fluid may comprise a volume proportion of helium-3 greater than 99.9%.

The invention also relates to a method for refrigeration using a device as described above, the method comprising the following steps:

• • compression of the first working fluid;
  • cooling of the first working fluid;
  • isenthalpic expansion of the first working fluid;
  • separation of the first working fluid into a first liquid phase and a second gas phase;
  • heating of the first fluid;
  • pumping of the first fluid.

In addition, the step of isenthalpic expansion of the first working fluid is carried out in such a way as to bring the first working fluid to a temperature of between 500 millikelvin and 4.5 kelvin prior to the separation step.

Advantageously, the method comprises the following steps:

• • compression of the second working fluid;
  • cooling of the second working fluid;
  • isenthalpic expansion of the second working fluid;
  • separation of the second working fluid into a first liquid phase and a second gas phase;
  • heating of the second fluid;
  • pumping of the second fluid.

Also advantageously, the step of isenthalpic expansion of the second working fluid is carried out in such a way as to bring the second working fluid to a temperature of between 300 and 700 millikelvin prior to the separation step.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it can admit to other equally effective embodiments.

Reference will be made to the appended drawings, in which:

FIG. 1 is a schematic representation of a first embodiment of the invention:

FIG. 2 is a schematic representation of a second embodiment of the invention:

FIG. 3 is a schematic representation of a third embodiment of the invention:

FIG. 4 is a schematic representation of a fifth embodiment of the invention:

FIG. 5 is a schematic representation of a sixth embodiment of the invention.

DETAILED DESCRIPTION OF THE INVENTION

With reference to FIG. 1, the refrigeration device according to the invention, and generally denoted 1, comprises a first working circuit 10 for circulating a first working fluid 11—in this case a fluid comprising a volume proportion of helium-4 equal to 99.9%. The circuit 10 also comprises the following thermodynamic effectors: a first compressor 20 for the fluid 11, a first cooling unit 300 comprising a first heat exchanger 310—in this case a countercurrent exchanger comprising a first hot channel 311 and a first cold channel 312. The cooling unit 300 also comprises a second heat exchanger 320 comprising a second hot channel 321 and a second cold channel 322. The circuit 10 also comprises a third heat exchanger 30, in this case a countercurrent exchanger comprising a third hot channel 31 and a third cold channel 32, a first Joule-Thomson expansion device 40 and a first phase separation tank 50. The device 1 also comprises a fourth heat exchanger 60 which comprises a fourth hot channel 61 in heat exchange with the first tank 50.

As can be seen in FIG. 1, the cold channel 322 is connected to an external cold source 330 according to the known methods. For example, the external cold source cools a working fluid to the desired temperature and this cooled fluid then circulates in the channel 322.

The device 1 also comprises a first network 70 of lines connecting the thermodynamic effectors to the working circuit 10 so as to place:

• • a first outlet 21 of the compressor 20, from which first outlet the fluid 11 is delivered, in fluidic communication with a first inlet 313 of the hot channel 311;
  • a second outlet 314 of the hot channel 311 in fluidic communication with a second inlet 323 of the hot channel 321;
  • a third outlet 324 of the hot channel 321 in fluidic communication with a third inlet 33 of the hot channel 31;
  • a fourth outlet 34 of the hot channel 31 in fluidic communication with a fourth inlet 41 of the expansion device 40;
  • a fifth outlet 42 of the expansion device 40 in fluidic communication with a fifth inlet 51 of the tank 50;
  • a sixth outlet 52 of the tank 50 in fluidic communication with a sixth inlet 35 of the cold channel 32;
  • a seventh outlet 36 of the cold channel 32 in fluidic communication with a seventh inlet 315 of the cold channel 312;
  • an eighth outlet 316 of the cold channel 312 in fluidic communication with an eighth inlet 22 of the compressor 20.

The device 1 also comprises a first cryogenic pump 80 situated in the circuit 10 between the sixth outlet 52 and the eighth inlet 22. More precisely, the ninth inlet 81 of the pump 80 is connected to the outlet 36 and the ninth outlet 82 of the pump 80 is connected to the seventh inlet 315. The pump 80 is then downstream of the outlet 36 and upstream of the inlet 22.

Lastly, the device 1 comprises a thermally insulated enclosure 5 inside which the circuit 10 and all the effectors of the device 1 that are listed above, with the exception of the compressor 20, are located.

During operation, the compressor 20 draws in the fluid 11 through the eighth inlet 22 and delivers it through the first outlet 21 after it has been subjected to preferably isothermal compression (the compressed fluid 11 is at the same temperature as the fluid 11 before compression). For example purposes, illustrative values will be used. The fluid 11 therefore enters through the eighth inlet 22 at a temperature close to ambient temperature (that is to say about 300 kelvin) and a pressure close to atmospheric pressure (that is to say about 1 bar). The fluid 11 exits the compressor 20 at a pressure of between 10 and 25 bar, preferably between 15 and 20 bar, and a temperature close to ambient temperature (that is to say about 300 kelvin). The compressed fluid 11 then enters the cooling unit 300 and exits it at a temperature of about 15 kelvin.

The fluid 11 then enters the hot channel 31 in which it is cooled by heat exchange with the flow circulating in the cold channel 32. The fluid 11 is then subjected to isenthalpic expansion in the expansion device 40 before entering the tank 50. The tank 50 then comprises two phases of the fluid 11 at very low temperature: a first liquid phase 12 and a second gas phase 13. The temperature of the fluid 11 present in the tank 50 is between 1.8 and 4.5 kelvin for an intake pressure of the pump 80 of between 15 millibar and 1 bar respectively. The tank 50 constitutes the fourth cold channel of the fourth exchanger 60 which can be used for the direct or indirect cooling, for example, of a quantum computer or of superconducting electronic components.

After having released cold energy to the hot channel 61 of the exchanger 60, the fluid 11 exits the tank 50 so as to enter the cold channel 32. At the outlet of the cold channel 32, the fluid 11 is pumped by the cryogenic pump 80 before being drawn in by the compressor 20. The cryogenic pump 80 then acts on the fluid 11 when the latter has a high volume density of helium-4 (corresponding to the working temperatures and pressures) and thus considerably increases the total flow rate of helium-4 in the circuit 10, making it possible to provide a significant cooling power for cooling the hot channel 61. The pump 80 is called “cryogenic” because it operates at temperatures lower than 50 kelvin.

To this end, the thermally insulated enclosure 5 is configured to contain all the elements of the device at a temperature lower than ambient temperature when the device is in operation.

Elements which are similar or analogous to those described above will bear an identical reference numeral to those in the following description of the second, third, fourth, fifth and sixth embodiments of the invention.

According to a second embodiment shown in FIG. 2, the device 1 comprises, in addition to the elements described above in relation to the first embodiment, a second Joule-Thomson expansion device 90 and a second phase separation tank 100 which are both connected to the circuit 10 by the network 70. As illustrated, the two tanks 100, 50 are disposed in series in the circuit. Equally, the two expansion devices 90, 40 are disposed in series in the circuit. The expansion device 90 comprises a tenth inlet 91 in fluidic communication with the circuit 10 downstream of the first outlet 21 and a tenth outlet 92 in fluidic communication with an eleventh inlet 101 of the second tank 100. An eleventh outlet 102 of the second tank 100 is in fluidic communication with the eighth inlet 22. The second tank 100 comprises, in this case, a first offtake 103 for fluid 11 in liquid phase which is in fluidic communication with the first circuit 10 upstream of the inlet 33 of the exchanger 30. The expansion device 90 and the second tank 100 are both situated inside the enclosure 5.

The assembly constituted by the second expansion device 90 and the second tank 100 allows the device 1 to implement a first temperature drop of the fluid 11 which will then, after passage through the expansion device 40, be at a temperature of the order of 1.8 kelvin in the first tank 50. This means that, with respect to the preceding embodiment, the example in FIG. 2 provides two separation tanks 100, 50 in series, the cryogenic pump 80 being configured to maintain a pressure of between 10 mbar and 20 mbar, typically 15 mbar, in the vapor phase in the first tank 50 in order to obtain a temperature of the liquid phase in the first tank 50 which is lower than the temperature of the second tank 100, and typically this temperature of the liquid phase in the first tank 50 is between 1.6 K and 3 K, typically 1.8 K.

According to a third embodiment shown in FIG. 3, the device 1 comprises a third Joule-Thomson expansion device 110, a third tank 120 and a fifth heat exchanger 130 (comprising a fifth hot channel 131 and a fifth cold channel 132) which are both connected to the circuit 10 by the network 70. The third expansion device 110 comprises a twelfth inlet 111 which is in fluidic communication with the circuit 10 downstream of the first outlet 21 and a twelfth outlet 112 which is in fluidic communication with a thirteenth inlet 121 of the third tank 120. The third tank 120 comprises a thirteenth outlet 122 in fluidic communication with the eighth inlet 22. The third tank 120 also comprises a second offtake 123 for fluid 11 in liquid phase in fluidic communication with a fourteenth inlet 133 of the hot channel 131. The fourteenth outlet 134 of the hot channel 131 is in fluidic communication with the first circuit 10 upstream of the third inlet 33. More precisely, and in this particular embodiment comprising three expansion devices in series and three tanks in series, the outlet 134 of the hot channel 131 is connected to the inlet 91 of the second expansion device 90.

The fifteenth inlet 135 and the fifteenth outlet 136 of the cold channel 132 are in fluidic communication with circuit 10 downstream of the outlet 36.

More precisely, and in this particular embodiment, the inlet 135 of the cold channel 132 is connected to the outlet 82 of the pump 80. The third expansion device 110, the third tank 120 and the fifth exchanger 130 are situated inside the enclosure 5.

The assembly constituted by the third expansion device 110 and the third tank 120 allows the device 1 to implement an additional temperature drop of the fluid 11 which will then, after passage through the expansion device 90, then the second tank 100 and then the expansion device 40, be at a temperature of the order of 0.8 to 1 kelvin in the tank 50.

According to a fourth embodiment shown by broken lines in FIG. 3, a second, optional cryogenic pump 140 is connected to the circuit 10 between the outlet 82 and the inlet 22 (in series with the first pump 80). More precisely, the pump 140 is connected to the outlet 136 of the exchanger 130. This means that, with respect to the preceding embodiments, the example in FIG. 3 provides three separation tanks in series, the cryogenic pump 80 being configured to maintain a pressure of between 0.015 millibar and 0.15 millibar in the vapor phase in the first tank 50 in order to obtain a temperature of the liquid phase lower than the temperature of the other tanks 120 and 100, this temperature in the first tank 50 being, for example, between 0.8 kelvin and 1 kelvin.

According to a fifth embodiment shown in FIG. 4, the device 1 comprises a sixth heat exchanger 150 comprising a sixth hot channel 151 and a sixth cold channel 152, a fourth Joule-Thomson expansion device 160 and a fourth tank 170.

The hot channel 151 comprises a sixteenth inlet 153 in fluidic communication with the first circuit 10 between the outlet 21 and the inlet 33. In the particular embodiment shown in FIG. 4, the inlet 153 is connected to the circuit 10 by a tapping produced between the offtake 103 and the inlet 33. The cold channel 152 comprises a sixteenth outlet 156 in fluidic communication with the circuit 10 downstream of the outlet 36. The outlet 154 of the hot channel 151 is connected to a seventeenth inlet 161 of the expansion device 160. The seventeenth outlet 162 of the expansion device 160 is connected to the eighteenth inlet 171 of the fourth tank 170 and the nineteenth outlet 172 of the fourth tank 170 is connected to the nineteenth inlet 155 of the cold channel 152. The fourth tank 170 serves as cold source for cooling the hot channel 61.1 of an additional fourth exchanger 60.1. Other additional exchangers, expansion devices and tanks may also be installed in parallel with the exchanger 150, the expansion device 160, the tank 170 and the additional exchanger 60.1 as shown by broken lines in FIG. 4.

It is thus possible to have a plurality of heat exchangers which distribute the cold power of the device 1 at several different points.

This means that, with respect to the preceding embodiments, the example in FIG. 4 provides several assemblies each comprising a heat exchanger 60, 60.1, a phase separation tank 50, 170, an expansion device 40, 160, and a heat exchanger 30, 150. These assemblies being supplied in parallel with working fluid by a single outlet 103 of the tank 100 and being connected in parallel to a single cryogenic pump 80.

According to a sixth embodiment shown in FIG. 5, the device 1 comprises a second working circuit 180 for circulating a second working fluid 181—in this case a fluid comprising a volume proportion of helium-3 greater than or equal to 99.9%. The circuit 180 also comprises, in addition to the effectors of the second embodiment, the following thermodynamic effectors: a second compressor 190 for the fluid 181, a fifth Joule-Thomson expansion device 200, a fifth phase separation tank 210, a third cryogenic pump 220, a seventh heat exchanger 230 and an eighth heat exchanger 240. The second compressor 190 is connected to a second cooling unit 250, which is identical to the cooling unit 300 and is connected to the cold source 330.

The device 1 also comprises a second network 260 of lines connecting the thermodynamic effectors so as to place:

• • a twentieth outlet 191 of the second compressor 190, from which twentieth outlet the fluid 181 is delivered, in fluidic communication with a twentieth inlet 251 of the cooling unit 250;
  • a twenty-first outlet 252 of the cooling unit 250 in fluidic communication with a twenty-first inlet 231 of a hot channel 232 of the exchanger 230;
  • a twenty-second outlet 233 of the hot channel 232 in fluidic communication with a twenty-second inlet 241 of a hot channel 242 of the exchanger 240;
  • a twenty-third outlet 243 of the hot channel 242 in fluidic communication with a twenty-third inlet 201 of the fifth expansion device 200;
  • a twenty-fourth outlet 202 of the fifth expansion device 200 in fluidic communication with a twenty-fourth inlet 211 of the fifth tank 210;
  • a twenty-fifth outlet 212 of the fifth tank 210 in fluidic communication with a twenty-fifth inlet 244 of a cold channel 245 of the exchanger 240;
  • a twenty-sixth outlet 246 of the cold channel 245 in fluidic communication with a twenty-seventh inlet 221 of the third pump 220;
  • a twenty-seventh outlet 222 of the third pump 220 in fluidic communication with a twenty-eighth inlet 234 of a cold channel 235 of the exchanger 230;
  • a twenty-eighth outlet 236 of the cold channel 235 in fluidic communication with a twenty-eighth inlet 253 of the cooling unit 250;
  • a twenty-ninth outlet 254 of the cooling unit 250 in fluidic communication with a twenty-ninth inlet 192 of the second compressor 190.

All the effectors of the circuit 180, with the exception of the second compressor 190, are situated inside the enclosure 5.

As can be seen in FIG. 5, the network 260 comprises a first line portion 261 which extends in the first tank 50, a second line portion 262 which extends in the second tank 100 and a third line portion 263 which extends in the third tank 120. The portions 261, 262 and 263 may be provided with radial fins in order to improve the heat exchanges with the fluid contained in the first tank 50, the second tank 100 and the third tank 120, respectively.

The portions 261, 262 and 263 are situated between the outlet 191 of the second compressor 190 and the inlet 201 of the fifth expansion device 200 and contribute to cooling the fluid 181 prior to its expansion in the fifth expansion device 200.

The cooling, using the circuit 10, of the fluid 181 which is present in the circuit 180 and which is itself subjected to isenthalpic expansion in the fifth expansion device 200 makes it possible to further lower the temperature of the cold channel in relation to the hot channel 61. The assembly constituted by the fifth expansion device 200 and the fifth tank 210 produces an additional temperature drop of the fluid 181 which will then, after passage through the fifth expansion device 200, be at a temperature of the order of 0.3 kelvin or less in the fifth tank 210.

Of course, the invention is not limited to the embodiments described but covers any variant falling within the scope of the invention as defined by the claims.

In particular:

• • although in this case the first fluid comprises a proportion of helium-4 greater than 99.9%, the invention also applies to other types of first fluid such as a first fluid comprising a proportion of helium-3 greater than 99.9% and with a temperature adapted from pre-cooling by the source 330;
  • although in this case the exchangers are countercurrent tube exchangers, the invention also applies to other types of heat exchangers, such as a plate or tube exchanger, the hot and cold flows being able to be in countercurrent or not;
  • the cryogenic pump may be a pump of the turbomolecular, “Holweck”, or centrifugal-wheel type, or any combination of these technologies;
  • although in this case the third pump has been shown between two separation tanks, the invention also applies to other placements of the second pump downstream of the twentieth outlet;
  • although in this case a third expansion device, a third tank and a third heat exchanger have been described in the context of a third embodiment comprising a second expansion device and a second tank, the invention also applies to a third expansion device, a third tank and a third heat exchanger which are coupled to a circuit that does not have a second expansion device and a second tank;
  • the second heat exchanger may be of the fluid or conduction exchanger type, for example a tank comprising at least one thermally conductive wall to which an element to be cooled is attached, or to which a thermally conductive braid is fastened;
  • although in this case the device comprises a second heat exchanger, the invention also applies to other types of objects to be cooled, such as an electronic chip in direct heat exchange with the first tank by conduction or in indirect heat exchange with the first tank using a heat transfer fluid or a solid heat transfer medium that may be metallic;
  • although in this case the cooling unit comprises a single first exchanger for transferring heat energy from a first hot channel to a first cold channel which are connected to the working circuit, and a single second heat exchanger comprising a second hot channel connected to the first working circuit and a second cold channel connected to an external cold source, the invention also applies to a cooling unit comprising two or more first exchangers for exchanging heat energy between two portions of the first circuit and/or two or more second exchangers connected to one or more external cold sources;
  • the cold source 330 may be comprised entirely or partially within the enclosure 5.
  • the cold source 330 may be a cycle gas refrigerator, a pulse tube, or any other suitable cold source;
  • the cold channel 322 may be replaced by a cryogenic liquid bath, at the desired evaporation temperature, in which the hot channel 321 is immersed.
  • the cold channel 322 may be replaced by an adaptable thermal link (copper or another thermally conductive metal) for mechanically connecting the cold source to the hot channel 321 and cooling it by conduction
  • the compressors 20 and 190 may be any transfer members, such as a line, a pump, a heat exchanger, or another suitable machine;
  • although in this case a compressor ensures the circulation of the working fluid in the circuit, the invention also applies to other types of transfer members such as a simple pipe or a heat exchanger. Specifically, the cryogenic pump 80 may suffice for pumping the fluid through all the lines of the circuit. This configuration can be obtained after starting of the device which comprises a hot transfer member such as a compressor. That is to say that the device is started by virtue of the compressor 20 (or 190) and then the compressor is switched off or bypassed by a cold exchanger which can be configured for heat exchange with a cold source for the purpose of pre-cooling;
  • although in this case the first and the second cooling unit use a single cold source, the invention also applies to cooling units using dedicated cold sources;
  • although in this case the fluid 11 exits the cooling unit 300 at a temperature of about 15 K, the invention also applies to an outlet temperature of the fluid 11 of 10 K, or of between 5 K and 10 K, notably between 6 K and 7 K.

While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.

The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.

“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.

“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.

Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.

Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.

All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.

Claims

1-17. (canceled)

18. A refrigeration device comprising a first working circuit for circulating a first working fluid, the first working circuit comprising the following elements connected in series by a first network of lines: a first transfer member for the working fluid;a cooling unit comprising a first heat exchanger comprising a first hot channel and a first cold channel that are connected to the first working circuit, the cooling unit also comprising a second heat exchanger comprising a second hot channel connected to the first working circuit and a second cold channel connected to a first cold source;a third heat exchanger comprising a third hot channel and a third cold channel;a first Joule-Thomson expansion device;a first tank configured to be in heat exchange with an object to be cooled; anda thermally insulated enclosure inside which at least some of the elements are located,wherein the first transfer member is situated outside the enclosure,wherein the first working circuit comprises a first pumping member situated inside the enclosure and connected to the first network of lines.

19. The refrigeration device as claimed in claim 18, wherein the first network of lines is configured to connect: a first outlet of the transfer member, from which first outlet the first working fluid is delivered, to a first inlet of the first hot channel;a second outlet of the first hot channel to a second inlet of the second hot channel;a third outlet of the hot channel to a third inlet of the third hot channel;a fourth outlet of the third hot channel to a fourth inlet of the first expansion device;a fifth outlet of the first expansion device to a fifth inlet of the first tank;a sixth outlet of the first tank to a sixth inlet of the third cold channel;a seventh outlet of the third cold channel to an eighth inlet of the first transfer member, through which eighth inlet the first working fluid is drawn;the first pumping member being situated between the sixth outlet and the eighth inlet.

20. The refrigeration device as claimed in claim 19, wherein the first pumping member is connected directly to the eighth inlet.

21. The refrigeration device as claimed in claim 18, the first pumping member is situated downstream of the seventh outlet.

22. The refrigeration device as claimed in claim 19, further comprising a second Joule-Thomson expansion device and a second tank, the second expansion device comprising a tenth inlet in fluidic communication with the first circuit downstream of the third outlet and a tenth outlet in fluidic communication with an eleventh inlet of the second tank, the second tank comprising an eleventh outlet in fluidic communication with the eighth inlet, the second tank also comprising a first offtake for working fluid in liquid phase in fluidic communication with the first circuit upstream of the third inlet.

23. The refrigeration device as claimed in claim 19, further comprising a third Joule-Thomson expansion device, a third tank and a fifth heat exchanger comprising a fifth hot channel and a fifth cold channel, the third expansion device comprising a twelfth inlet in fluidic communication with the first circuit downstream of the third outlet and a twelfth outlet in fluidic communication with a thirteenth inlet of the third tank, the third tank comprising a thirteenth outlet in fluidic communication with the eighth inlet, the third tank also comprising a second offtake for working fluid in liquid phase in fluidic communication with a fourteenth inlet of the fifth hot channel, a fourteenth outlet of the fifth hot channel being in fluidic communication with the first circuit upstream of the third inlet, a fifteenth inlet and a fifteenth outlet of the fifth cold channel being in fluidic communication with the first circuit downstream of the seventh outlet.

24. The refrigeration device as claimed in claim 19, further comprising a sixth heat exchanger comprising a sixth hot channel and a sixth cold channel, a fourth Joule-Thomson expansion device and a fourth tank, the sixth hot channel comprising a sixteenth inlet in fluidic communication with the first working circuit between the first outlet and the third inlet and the sixth cold channel comprises a sixteenth outlet in fluidic communication with the first working circuit downstream of the fifth outlet.

25. The refrigeration device as claimed in claim 18, wherein the first working fluid comprises a volume proportion of helium-4 greater than or equal to 99.9%.

26. The refrigeration device as claimed in claim 18, further comprising a second working circuit for circulating a second working fluid by means of a second transfer member and a second cryogenic pump, the second working circuit comprising at least one first line portion in heat exchange with the first tank.

27. The refrigeration device as claimed in claim 26, wherein the second transfer member is situated outside the enclosure.

28. The refrigeration device as claimed in claim 26, wherein the second working circuit comprises at least one second line portion in heat exchange with the second tank.

29. The refrigeration device as claimed in claim 26, wherein the second working circuit also comprises a fifth Joule-Thomson expansion device.

30. The refrigeration device as claimed in claim 26, wherein the second working fluid comprises a volume proportion of helium-3 greater than or equal to 99.9%.

31. A method for refrigeration using a device as claimed in claim 18, comprising the following steps: compression of the first working fluid;cooling of the first working fluid;isenthalpic expansion of the first working fluid;separation of the first working fluid into a first liquid phase and a second gas phase;heating of the first fluid; andpumping of the first fluid.

32. The method as claimed in claim 31, wherein the step of isenthalpic expansion of the first working fluid is carried out in such a way as to bring the first working fluid to a temperature of between 500 millikelvin and 4.5 kelvin prior to the separation step.

33. A method for refrigeration using a device as claimed in claim 18, comprising the following steps: compressing the second working fluid;cooling the second working fluid;isenthalpically expanding the second working fluid;separating the second working fluid into a first liquid phase and a second gas phase;heating the second fluid; andpumping the second fluid.

34. The method as claimed in claim 33, wherein the step of isenthalpic expansion of the second working fluid is carried out in such a way as to bring the second working fluid to a temperature of between 300 and 700 millikelvin prior to the separation step.