Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K5/00—Heat-transfer, heat-exchange or heat-storage materials, e.g. refrigerants; Materials for the production of heat or cold by chemical reactions other than by combustion
  • C09K5/08—Materials not undergoing a change of physical state when used
  • C09K5/14—Solid materials, e.g. powdery or granular
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C11/00—Alloys based on lead
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C12/00—Alloys based on antimony or bismuth
• • C—CHEMISTRY; METALLURGY
  • C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
  • C22C—ALLOYS
  • C22C9/00—Alloys based on copper
• • 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
  • F25B9/14—Compression machines, plants or systems, in which the refrigerant is air or other gas of low boiling point characterised by the cycle used, e.g. Stirling cycle
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B22—CASTING; POWDER METALLURGY
  • B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
  • B22F2998/00—Supplementary information concerning processes or compositions relating to powder metallurgy
• • 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
  • F25B2309/003—Gas cycle refrigeration machines characterised by construction or composition of the regenerator

Definitions

• the present invention relates to a regenerator material, a regenerator, and a cryogenic regenerator type refrigerator, and in particular, a GM (Gifford McMahon) cycle refrigerator, a Stirling cycle refrigerator, a Nors tube refrigerator, and a Bill Mier cycle refrigerator.
• a refrigeration system a superconducting magnet, a nuclear magnetic resonance imaging (MRI) apparatus, a cryopump, a cryogen purification apparatus, a superconducting element cooling apparatus, and the like using the same.
• MRI nuclear magnetic resonance imaging
• cryopump a cryogen purification apparatus
• superconducting element cooling apparatus and the like using the same.
• regenerator material a material having a large specific heat at a target temperature is used.
• a refrigerator has a wide temperature range up to 4K at room temperature. Therefore, it is necessary to select a material with as much specific heat as possible in the entire range. Specific heat varies greatly depending on the material, and no single material can handle the entire temperature range. Therefore, the most suitable materials are used in combination with the temperature.
• wire mesh copper or stainless steel is used from room temperature to around 50K, and spherical lead is used at lower temperatures. Lead has been widely used because it has a higher specific heat than other materials, a certain degree of structural strength, and is inexpensive at a low temperature range of 50 K or less (see, for example, JP-A-3-99162). See).
• JP-A-2004-225920 discloses an alloy of indium and bismuth and a third material. Since indium has a specific heat next to lead at temperatures below 50K, it is an idea to make use of its characteristics.
• indium is a very soft metal, it cannot be used as a cold storage material as it is, but by using an alloy with bismuth or another metal, the hardness required for the cold storage material is increased. However, it is still insufficient for use as a cold storage material. Also, the price of indium is about three times that of lead, and it is too expensive to be used as a cold storage material!
• the present invention has been made to solve the above-mentioned conventional problems, and has low mechanical toxicity and sufficient mechanical strength to be easily used.
• the issue is to provide a regenerator material that has excellent thermal properties when used.
• the present invention is a bismuth or bismuth-antimony alloy granule, wherein the proportion of particles having a particle size of 0.14 mm or more and 1.6 mm or less is 70% by weight or more with respect to the total particles.
• the above problem was solved by a cold storage material characterized in that the ratio of the granule whose ratio of the major axis to the minor axis is 5 or less is 70% by weight or more with respect to the whole granule. Is.
• the surface roughness of the particles is set to 100 ⁇ m or less on the basis of the maximum height Rmax.
• the present invention is also characterized in that the particles are bismuth or bismuth-antimony alloy particles, and the particle surface strength is 100 m or less on the basis of the maximum height Rmax. This problem is solved by the regenerator material.
• the structure of the granule is such that at least a part thereof contains an amorphous phase.
• the ratio of the particles having microdefects having a length of 10 ⁇ m or more to the total particles in the granules is 30% by weight or less.
• the surface of the granule is not discolored by acid soot.
• the bismuth or alloy particles of bismuth and antimony are sintered and processed into a block shape, a pellet shape, or a plate shape.
• the present invention also solves the above problems by using a reticulated regenerator material characterized in that the mesh opening of bismuth or an alloy of bismuth and antimony is changed from 0.01 mm to lmm. .
• a reticulated regenerator material characterized in that bismuth or an alloy of bismuth and antimony is applied or stuck to the surface of a metal net having an opening of 0. lmm to lmm. is there.
• the present invention also provides a regenerator characterized by being filled with the above regenerator material.
• the present invention provides a regenerator characterized by having a laminated structure of two or more layers composed of the regenerator material and a magnetic regenerator material.
• the magnetic regenerator material is HoCu, HoCu and Gd O S or GAP (GdAlO), Er Ni
• the present invention also provides a cryogenic regenerative refrigerator that includes the regenerator described above.
• regenerator is used in the lowest temperature cooling stage.
• the regenerator is used for an intermediate cooling stage, and another magnetic material having a large specific heat of 4K or less is used for the final cooling stage regenerator.
• the present invention also provides a refrigeration system comprising a pre-cooling stage using the above refrigerator and at least one other cooling means.
• the present invention provides a superconducting magnet, an MRI apparatus, a cryopump, a cryogen refining apparatus, a superconducting element cooling apparatus, or the like characterized by comprising the above refrigerator or refrigeration system.
• the load on the environment is relatively low.
• it is a condition required for cold storage materials, is easily spheroidized, has sufficient mechanical strength to be used, is inexpensive, and is used for refrigerators. Satisfies the requirements for cold storage materials, such as sometimes having excellent thermal properties.
• FIG. 1 An explanatory view schematically showing the outline of the cryogenic refrigerator of the first embodiment according to the present invention.
• FIG. 2 A diagram showing an example of the relationship between bismuth size and 4.2K refrigeration capacity.
• FIG. 5 Diagram showing the rotational speed dependence of the minimum temperature when there is no load in Example 1 of the present invention.
• FIG. 6 Diagram showing the rotational speed dependence of the two-stage refrigeration capacity when there is no single load.
• FIG.8 Diagram showing the temperature dependence of the first stage of the second stage refrigeration capacity at 4.2K when the first stage is also loaded.
• FIG. 12 is a cross-sectional view showing the main configuration of a two-stage regenerator compared in Example 2
• FIG. 13 Diagram showing comparison of refrigerating capacity due to difference in regenerator configuration in Example 2.
• FIG. 16 is a schematic cross-sectional view showing the overall configuration of a second embodiment in which the refrigerator of the present invention is applied to an MRI apparatus.
• FIG. 1 schematically shows an outline of a regenerative cryogenic refrigerator according to the first embodiment of the present invention.
• the present invention is applied to a two-stage GM refrigerator.
• a high-pressure refrigerant gas is supplied from a compressor 11 as shown through a high-pressure gas pipe 12 and a high-pressure valve 13, and passes through a low-pressure valve 14 and a low-pressure gas pipe 15. Recovered as low-pressure gas.
• a first-stage regenerator 21 and a two-stage regenerator 31 are accommodated in a first-stage cylinder 2 and a second-stage cylinder 3, respectively, and both the regenerators 21 and 31 are driven by a drive motor 16 to move vertically. By reciprocating, the lower end side of each cooler is cooled.
• the first-stage regenerator 21 and the second-stage regenerator 31 are filled with a first-stage regenerator 22 and a two-stage regenerator 32, respectively.
• the first-stage regenerator material 22 is formed by laminating, for example, 970 metal meshes made of copper mesh 150.
• the two-stage regenerator (displacer) 31 has a two-layer stacked structure in which a two-stage regenerator material 32 as shown in the figure is partitioned at approximately the same amount by volume, and the low temperature of the second layer
• the side regenerator 32B is filled with granular HoCu, and the first layer of the high temperature side regenerator 32A
• the cooling section of the refrigerator 1 of the present embodiment includes a first-stage cooler 21 and a second-stage cooler 31 that are respectively housed in the first-stage cylinder 2 and the second-stage cylinder 3 that are integrally formed.
• the first stage cooling stage 23 at the lower end (low temperature end) of the first stage cylinder is cooled to about 40K
• the second stage cooling stage 33 at the lower end of the second stage cylinder is cooled to, for example, 7K or less.
• an electric heater (not shown) is attached to each of the first-stage cooling stage 23 and the second-stage cooling stage 33, and a heat load is applied by the electric input so that the refrigeration capacity of each stage can be measured. Yes.
• 24 is a gas passage of the first-stage regenerator 21
• 25 is a seal for airtightness between the first-stage cylinder 2
• 26 is a first-stage expansion space
• 34 is a two-stage regenerator.
• the gas passage 36 is a two-stage expansion space and the displacer stroke is 25 mm.
• the seal between the two-stage regenerator 31 and the two-stage cylinder 3 is omitted.
• the granular bismuth filled as the high temperature side cold storage material 32A can have a purity of 99.99%, for example, and its particle size is 0.14-1.6mm, preferably 0.15: L 4 mm, more preferably 0.22: L 3 mm.
• Fig. 2 shows an example of the relationship between the bismuth size (particle size) and the refrigerating capacity of 4.2K.
• the particle size is less than 0.14 mm, the density when filling the regenerator becomes too high, and the passage resistance of the He gas as the cooling medium increases rapidly. And the particle size is 1.6mm If it exceeds, the heat exchange efficiency between the particles and the cooling medium may be significantly reduced.
• the ratio of the maximum diameter to the minimum diameter (aspect ratio) of the bismuth regenerator material of the present embodiment is 5 or less, preferably 3 or less, more preferably 2 or less, further possible in any three-dimensional direction. It is preferable to make it as close to a sphere as possible. If the aspect ratio exceeds 5, mechanical deformation is likely to occur, and it becomes difficult to fill with high density, resulting in a decrease in cooling efficiency.
• the bismuth regenerator material has a purity of 99.99% or more, a particle size of 0.3 to 0.5 mm, and an aspect ratio. Granules with a ratio of 5 or less are used. Unless otherwise specified, the operation cycle by the motor 16 is 60 rpm, and the displacer stroke is 30 mm.
• FIG. 3 shows the volume specific heat characteristics of the bismuth used in the present invention as a material for a cold storage material in a low temperature region in comparison with materials used as another cold storage material.
• Bismus Bi is also used in cosmetics, so it is considered safe and environmentally friendly and there is no need to worry about environmental pollution.
• the force required to have a large volumetric specific heat in the intended cryogenic temperature region, bismuth does not reach that of lead Pb as seen in Figure 3.
• GOS is an abbreviation for GdOS.
• Table 1 shows the hardness measurement results of the regenerator material evaluated in Example 1.
• bismuth spheres can be said to be equivalent to lead.
• the hardness of the B-mouth with a black surface is lower than that of the A-lot with a gold surface, but this may be due to surface oxidation.
• strength when compressive strength was measured, deformation due to compression was not However, the cracking of the material with less lead was also observed. From this, it was found that bismuth has the same strength as lead, and it has become a component.
• FIG. 5 shows the rotation speed dependency of the minimum temperature. 2nd stage temperature T is almost the same, but 1st stage temperature
• T is 2K lower than lead ( ⁇ mark) when bismuth ( ⁇ mark) is used in the whole rotation speed range.
• FIG. 6 shows the rotation speed dependency of the second stage refrigerating capacity when there is no first stage load.
• bismuth ( ⁇ mark) shows a higher refrigerating capacity than lead ( ⁇ mark).
• the highest freezing capacity was obtained at 48 rpm.
• Figure 7 shows the refrigeration capacity diagram at 60 rpm.
• the first stage temperature was lower with bismuth than with lead. Reflecting the results, it can be seen that bismuth ( ⁇ ) shows a lower temperature than lead ( ⁇ ) even when a load is applied to the first stage.
• Fig. 8 shows a comparison of the two-stage refrigeration capacity when the first stage is loaded.
• Bismuth ( ⁇ mark) shows higher refrigerating capacity than lead ( ⁇ mark) at any one stage temperature. The difference increases as the first stage temperature increases. At around 45K, a large difference of about 10% is seen in the 4.2K two-stage refrigeration capacity.
• Figure 9 shows the first-stage temperature dependence of the two-stage refrigeration capacity with the bismuth condition as a parameter. Yes.
• the black dots correspond to B lot and the white dots correspond to A lot.
• the difference between lots is larger than the difference due to the particle size in the same lot.
• Figure 10 shows the difference in the two-stage refrigeration capacity depending on the particle size of bismuth. 1st stage temperature T 25K ⁇ 45
• Fig. 11 shows the case of the first-stage refrigeration capacity. This is in contrast to the obvious particle size dependence seen with lead.
• Example 2 [0057] Next, we evaluated the bismuth characteristics in the temperature range above 10K with a 4.2K machine with a freezing capacity of 0.5W.
• GM refrigerators are used in areas other than 4K, such as cryopumps and above 10K.
• all lead is used as a cold storage material in this temperature range.
• the refrigeration capacity decreased by 30% or more in the temperature range above 10K. Therefore, when lead-free becomes indispensable, it may not be possible to replace all lead with bismuth due to insufficient refrigerating capacity. Therefore, an experiment was conducted to find out how to use bismuth to achieve a refrigerating capacity equivalent to that of lead.
• Er Ho Ni has a large specific heat peak around 15K.
• GOS was excluded from the evaluation because the specific heat dropped extremely above the specific heat peak around 5K.
• the refrigerator used was a 4.2K machine with a refrigeration capacity of 0.5 W, and the cylinder dimensions were a first stage inner diameter of 52 mm, a length of 191.5 mm, a second stage inner diameter of 25 mm, and a length of 165 mm.
• the stroke was 25 mm
• the filling pressure was 19 kgf / cm 2 G
• the displacer motor rotation speed was 60 rpm.
• a single-stage regenerator is filled with 900 pieces of 150 mesh copper mesh.
• the operating frequency of the compressor was 50Hz
• Fig. 12 shows the configuration of the regenerator compared in this example
• Fig. 13 shows the difference in refrigerating capacity due to the difference in the regenerator configuration.
• the minimum temperature reached in the second stage was 4K or less only when HoCu was filled.
• the lower temperature is 2.78K for regenerator 2, which is very different from 6.14K for regenerator 3 with all bismuth.
• the first stage was the lowest in the case of the regenerator 3 made of bismuth, and the temperature was achieved.
• the two-stage capacity shown in Fig. 14 is the power that decreases in comparison with lead (regenerator 1) in the case of bismuth (regenerator 3).
• the low-temperature side 1Z4 of bismuth is converted to HoCu (regenerator 5) or Er Ho Ni (cold storage
• the first-stage refrigeration capacity shown in FIG. 15 is improved by bismuth. That is, all bismuth
• the value is particularly large.
• the effect that the two-stage temperature has on the first-stage refrigeration capacity is as high as 20K, and the first-stage refrigeration capacity is equivalent to, or rather inferior to, the hybrid regenerator.
• the combination of bismuth and HoCu is excellent as a regenerator configuration to replace lead.
• the regenerator material that also serves as the bismuth of the present embodiment is superior to lead in terms of environment, and is superior in terms of magnetic regenerator material such as HoCu, Gd OS, and other types of regenerators.
• the magnetic regenerator material used in combination with HoCu is not limited to the Gd O S, but GAP (Gp)
• elements R and R are replaced with yttrium Y, lanthanum La, cerium Ce, praseodymium! ⁇ , Neodymium Nd, promethium Pm, samarium Sm, europium Eu, gadolinium Gd, tenolepium Tb, dysprosium Dy, holmium Ho, erbium.
• Er, thulium Tm, or yttel beam Yb may be used.
• Er Co can also be used instead of Er Ni.
• the regenerator material is made of granular material (powder) of bismuth alone.
• the regenerator material of the present invention is not limited to bismuth alone, and bismuth is the main component. It may be an alloy.
• As an alloy component there is antimony (Sb), and there is an advantage that the hardness can be increased by making such an alloy, for example, containing up to about 5 to 10%.
• a granular regenerator material made of bismuth or an alloy containing bismuth as a main component is a molten metal that uses a rotating disk, a roll, a rotating nozzle or the like to rapidly cool the molten metal simultaneously with granulation. It may be manufactured by a rapid cooling method, or it may be manufactured by an arbitrary manufacturing method such as a plasma spray method or a gas atomizing method.
• the first embodiment of the present invention is an MRI apparatus using the two-stage GM refrigerator of the first embodiment.
• FIG. 1 A second embodiment is shown in FIG. 1
• the superconducting magnet 45 is used to create the magnetic field space 48.
• the superconducting magnet 45 is immersed in a liquid helium 44 and cooled to a superconducting state.
• Liquid helium is injected through the inlet 46.
• the helium vaporized by the condensing part 47 provided inside the liquid helium container 43 is returned to the liquid, and the helium can be operated without being replenished for a long time. is there.
• the condensing unit 47 is thermally coupled to the two-stage cooling stage 33 of the GM refrigerator 1 and is continuously supplied with cold.
• the heat shield 42 is cooled by the first cooling stage 23 of the GM refrigerator 1.
• the refrigerator 1 is used for recondensing the liquid helium 44.
• the liquid helium is eliminated, and the refrigerator 1 directly cools the superconducting magnet 45 by heat conduction. It can also be configured.
• a heat shield can be added to make a so-called shield-cooled type that cools the separate heat shield for each of the first-stage cooling stage 23 and the second-stage cooling stage 3 3 force
• the present invention is applied to a GM cycle refrigerator.
• the application target of the present invention is not limited to this, and a pulse tube refrigerator, a Joule'Thomson refrigerator, a Stirling cycle refrigerator. It is clear that it can be applied to other regenerator-type cryogenic refrigerators such as refrigerators, Birmier cycle refrigerators, and Solvay cycle refrigerators.
• the system using the regenerator type cryogenic refrigerator according to the present invention is not limited to the MRI apparatus of the second embodiment, but is an NMR apparatus, a superconducting magnet apparatus, a cryopump, a Josephson voltage standard apparatus. , Cryogen equipment, superconducting element cooling device, helium recondensing device, etc. Obviously, the same applies.
• the shape of the regenerator material is not limited to a granular material, and can be filled into a regenerator after being sintered and processed into a block shape, a pellet shape, or a plate shape.
• the regenerator material can be formed in a net shape having an opening of 0.01 mm to lmm, or can be formed by applying or clinging to a metal net surface having an opening of 0.1 Olmm to lmm.

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• Devices That Are Associated With Refrigeration Equipment (AREA)

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• 2005
  • 2005-03-03 JP JP2005059648A patent/JP2006242484A/ja active Pending
  • 2005-05-27 WO PCT/JP2005/009775 patent/WO2006092871A1/ja not_active Ceased
  • 2005-05-27 EP EP05743907.7A patent/EP1854859B1/en not_active Expired - Lifetime
  • 2005-05-27 CN CN2005800483862A patent/CN101124289B/zh not_active Expired - Lifetime
  • 2005-05-27 US US11/793,653 patent/US20080104967A1/en not_active Abandoned

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