Heat exchanger for a dilution refrigerator, manufacturing method and dilution refrigerator

Abstract

This invention provides a heat exchanger for a dilution refrigerator, a manufacturing method thereof, and the dilution refrigerator itself, relating to the field of dilution refrigerator technology. The heat exchanger includes multiple sequentially connected heat exchange units, each unit comprising a heat-conducting element, two covers, and a filling material. The two covers are respectively disposed on both sides of the heat-conducting element to define a first chamber and a second chamber. A flow-through flow mechanism is present in the first chamber. 3 He solution, with flow in the second chamber. 3 He solution and 4 A mixture of He solutions, to make 3 The He solution and the mixture exchange heat through a heat-conducting element. A packing material is disposed in the first and second chambers, and a first pore system is formed inside the packing material to facilitate the increase of heat exchange. 3 The heat exchange area between the He solution and the mixture is increased. A second pore system is also formed inside the packing, which is suitable for increasing the heat exchange area while simultaneously increasing... 3 The depth to which He solution and mixture penetrate into the interior of the filler.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of heat exchange and dilution refrigerator, and more particularly, to a heat exchanger for dilution refrigerator, a manufacturing method and a dilution refrigerator. BACKGROUND

[0002] Dilution refrigerator is an indispensable core equipment in the field of ultra-low temperature experimental physics, and its working temperature can be as low as millikelvin (mk) level. At ultra-low temperature (such as generally lower than 0.87 k), 3 He- 4 The He mixture will undergo phase separation to form a concentrated phase rich in 3 He and a dilute phase rich in 4 He. The dilution refrigeration cycle realizes refrigeration by continuously dissolving 3 He atoms in the dilute phase from the concentrated phase. This process requires heat absorption because the transfer of 3 He atoms from the concentrated phase with high chemical potential to the dilute phase with low chemical potential is an endothermic process, similar to the evaporation of a liquid. By designing the circulation system, the gaseous 3 He is continuously extracted from the dilute phase by a vacuum pump, purified and condensed, and then re-injected into the concentrated phase, finally establishing and maintaining a stable ultra-low temperature environment at the millikelvin level in the mixing chamber.

[0003] In the dilution refrigerator, the performance of the heat exchanger is a key factor in determining whether the millikelvin level temperature can be ultimately reached. Its role is to perform efficient heat exchange between the returned circulation 3 He solution with higher temperature and the 4 He mixture with lower temperature, significantly reducing the load of the subsequent refrigeration stage. If the heat exchanger is inefficient, the returned heat flow will bring huge heat leakage, making the refrigeration cycle unable to establish the required ultra-low temperature environment. Therefore, the design of the heat exchanger in the dilution refrigerator faces stringent requirements, and near-ideal thermal efficiency (usually more than 99%) is pursued. For this purpose, a compact and large surface area counterflow design is often used, and high thermal conductivity materials such as oxygen-free copper are selected to ensure efficient heat transfer under a small temperature difference.

[0004] In related technologies, nano-silver sintered bodies are usually used inside the heat exchanger to increase the heat exchange area. The reason is that the porous structure provides a large surface area, and the metal silver itself has good thermal conductivity. However, there are still some defects, such as 3 He solution, 3 He- 4The permeability of the He mixed solution is limited, and the thickness of the sintered body cannot be designed to be too thick. This makes it impossible to further increase the heat exchange area, and the volume of the sintered body can only be expanded by increasing the bottom area of the sintered body, which will increase the horizontal space occupation and affect the arrangement of other structures near the cold plate, and the amount of helium will also increase significantly, resulting in increased cost. Therefore, how to provide a heat exchanger to solve the above defects has become a technical problem to be solved. SUMMARY

[0005] Therefore, the present application provides a heat exchanger for a dilution refrigerator, which improves the heat exchange area of the sintered body by the cooperation of the first hole system and the second hole system, and improves the adaptability to the dilution refrigerator. 3 He solution and 3 He solution and 4 The permeability of the He mixed solution enables the filler to obtain a larger heat exchange area by increasing the thickness, thereby improving the adaptability to the dilution refrigerator.

[0006] To achieve the above purpose, the present application provides a heat exchanger for a dilution refrigerator, comprising a plurality of heat exchange units connected in sequence, wherein the heat exchange unit comprises: a heat conducting member; two cover bodies respectively covering the two sides of the heat conducting member to define a first chamber and a second chamber, the first chamber has flowing 3 He solution, the second chamber has flowing 3 He solution and 4 He solution, so that the 3 He solution and the mixed solution exchange heat through the heat conducting member; a filler is arranged in the first chamber and the second chamber, and the filler has a first hole system formed therein, which is suitable for increasing the heat exchange area of the 3 He solution and the mixed solution, and the filler also has a second hole system formed therein, which is suitable for increasing the heat exchange area while increasing the depth of penetration of the 3 He solution and the mixed solution into the filler.

[0007] According to the embodiment of the present application, the first hole system comprises a plurality of heat exchange holes, the second hole system comprises a plurality of seepage holes, and the diameter of the seepage holes is greater than the diameter of the heat exchange holes.

[0008] According to the embodiment of the present application, the filler comprises a sintered body made of nano-silver powder.

[0009] According to the embodiment of the present application, the first chambers of adjacent heat exchange units are connected, and the second chambers of adjacent heat exchange units are connected; wherein the connected first chambers serve as the hot side of the heat exchanger, and the connected second chambers serve as the cold side of the heat exchanger.

[0010] The present invention also provides a method for manufacturing a heat exchanger for a dilution refrigerator as described in any of the above embodiments, comprising: preparing a second porous framework using 3D printing technology; placing the second porous framework into a mold, filling the mold with nano-silver powder to cover the second porous framework and compacting it into a block; removing the second porous framework using a solvent, retaining the nano-silver powder block; sintering the nano-silver powder block to form a sintered body having a first porous system and a second porous system; repeating the above steps to prepare multiple sintered bodies, processing multiple heat-conducting components and multiple covers; placing the sintered bodies into a first chamber and a second chamber and sealing them to obtain multiple heat exchange units; and connecting the multiple heat exchange units through pipes.

[0011] Embodiments of the present invention also provide a dilution refrigerator, including a heat exchanger for a dilution refrigerator as described in any of the above embodiments, and further including: a mixing chamber, wherein the mixing chamber stores a material located in the upper layer. 3 He condensed phase and the lower layer 3 He dilution phase, the above 3 The concentrated phase of He is configured in response to the above 3 He dilution phase 3 The concentration of He decreased, towards the above 3 He dilution phase compensation 3 He simultaneously absorbs ambient heat for cooling; the evaporator section, connected to the aforementioned mixing chamber, stores at least a portion of the aforementioned... 3 He dilution phase, the above-mentioned evaporation section is configured to dilute the above-mentioned phase. 3 He dilution phase 3 He evaporates and is then condensed to form... 3 He solution flows back to the above 3 The concentrated phase is used to form a circulating dilution refrigeration with the aforementioned mixing chamber; the aforementioned heat exchanger is disposed between the aforementioned mixing chamber and the aforementioned evaporation section, and has a hot side and a cold side, wherein the hot side is suitable for... 3 He solution flows back to the above 3 He concentrated phase, the above-mentioned cold side is suitable for connecting the above-mentioned mixing chamber and the above-mentioned evaporation section. 3 He is diluted phase to exchange heat with the aforementioned hot side.

[0012] According to an embodiment of the present invention, the evaporation section includes an evaporation chamber, which communicates with the mixing chamber via the cold side to store at least a portion of the mixture. 3 He dilution phase, suitable for diluting the above 3 He dilution phase 3 He evaporates 3 He steam; 3 The internal circulation device is configured to adsorb the contents of the evaporation chamber in response to the device temperature being in the second temperature zone. 3He vapor, and in response to the device temperature being in the first temperature zone, release 3 He steam, the above 3 He vapor, after being released and condensed, enters the hot side of the heat exchanger.

[0013] According to embodiments of the present invention, the above 3 The internal circulation device includes: at least one pair of circulation bodies disposed between a primary cold plate and a secondary cold plate spaced apart in a vertical direction, wherein the temperature of the primary cold plate is in a first temperature zone and the temperature of the secondary cold plate is in a second temperature zone, and each circulation body in each pair of circulation bodies has the function of moving downward to contact the secondary cold plate and cooling down to the second temperature zone to adsorb the evaporation chamber. 3 The first state of He vapor, and its upward movement to contact the aforementioned primary cold plate and rise to the aforementioned first temperature zone, so as to be released into the aforementioned mixing chamber. 3 The second state of He vapor; a drive mechanism adapted to drive two of the two circulating bodies in each pair to move vertically to switch between the first state and the second state, and to keep the two circulating bodies in different states, thus constituting a configuration. 3 He steam internal circulation path.

[0014] According to an embodiment of the present invention, the above-mentioned circulation body includes: a movable tube extending in a vertical direction and connected to the drive mechanism, the movable tube having a shape suitable for accommodating... 3 The first containment cavity for He vapor; two heat-conducting valve seats, respectively located at two openings of the aforementioned movable tube, and at least partially extending into the aforementioned movable tube, wherein the heat-conducting valve seats are formed with a supply... 3 He is a steam flow channel; two elastic sleeves are adapted to connect the movable tube and the heat-conducting valve seat, the elastic sleeves, the heat-conducting valve seat and the movable tube define a second receiving cavity communicating with the flow channel, the movable tube is configured to compress one of the elastic sleeves under the drive of the drive mechanism, such that the second receiving cavity on the same side as the elastic sleeve communicates with the first receiving cavity.

[0015] According to an embodiment of the present invention, each of the above-mentioned circulating bodies further includes an adsorption element disposed within the first receiving cavity and configured to release under conditions of a first temperature zone. 3 He vapor, and adsorption in the second temperature zone 3 He steam.

[0016] The heat exchanger for a dilution refrigerator provided by this invention, through the combined action of a first pore system and a second pore system, enables... 3The He solution and the mixed solution can easily penetrate into the filling body and fully exchange heat with the filling body, so that the filling body can obtain greater heat exchange area by increasing thickness, and the dilution refrigerator is better adapted, and the space is not excessively increased due to the increase of the bottom area, 3 Waste of the He solution and the mixed solution. BRIEF DESCRIPTION OF DRAWINGS

[0017] Figure 1 is a perspective view of a heat exchanger for a dilution refrigerator provided by an embodiment of the present application;

[0018] Figure 2 is a perspective view of a heat exchange unit of the heat exchanger provided by an embodiment of the present application;

[0019] Figure 3 is a sectional view of the heat exchange unit provided by an embodiment of the present application;

[0020] Figure 4 is a sectional view of the heat exchange unit provided by an embodiment of the present application;

[0021] Figure 5 is a flow chart of a manufacturing method of the heat exchanger for the dilution refrigerator provided by an embodiment of the present application;

[0022] Figure 6 is a perspective view of the heat exchanger for the dilution refrigerator provided by an embodiment of the present application after the mixing chamber and the evaporation chamber are connected;

[0023] Figure 7 is a plan view of the heat exchanger for the dilution refrigerator provided by an embodiment of the present application after the mixing chamber and the evaporation chamber are connected;

[0024] Figure 8 is a plan view of the dilution refrigerator provided by an embodiment of the present application;

[0025] Figure 9 is a perspective view of the dilution refrigerator provided by another embodiment of the present application;

[0026] Figure 10 is a perspective view of the dilution refrigerator provided by an embodiment of the present application 3 is a plan view of the He internal circulation device provided by an embodiment of the present application;

[0027] Figure 11 is a perspective view of the He internal circulation device provided by an embodiment of the present application 3 is a perspective view of the He internal circulation device provided by an embodiment of the present application;

[0028] Figure 12 is a perspective view of the He internal circulation device provided by an embodiment of the present application 3 is a perspective view of the circulation main body of the He internal circulation device provided by an embodiment of the present application;

[0029] Figure 13The circulating main body of the He internal circulating device is shown in Fig. 4. 3 The circulating main body of the He internal circulating device is shown in Fig. 4.

[0030] Figure 14 The circulating main body of the He internal circulating device is shown in Fig. 4. 3 The circulating main body of the He internal circulating device is shown in Fig. 4.

[0031] Figure 15 The circulating main body of the He internal circulating device is shown in Fig. 4. Figure 13 The circulating main body of the He internal circulating device is shown in Fig. 4.

[0032] Figure 16 The circulating main body of the He internal circulating device is shown in Fig. 4. 3 The circulating main body of the He internal circulating device is shown in Fig. 4.

[0033] In the drawings, the meanings of the reference numerals are as follows:

[0034] 1. Heat exchange unit

[0035] 11. Heat conducting member

[0036] 12. Cover body

[0037] 13. Filling body

[0038] 2. Mixing chamber

[0039] 3. Evaporation chamber

[0040] 4. Circulating main body

[0041] 41. Movable pipe body

[0042] 411. First accommodating cavity

[0043] 412. Large diameter section

[0044] 413. Small diameter section

[0045] 4131. Through hole

[0046] 42. Heat conducting valve seat

[0047] 421. Heat conducting disc

[0048] 422. Valve body

[0049] 423. Flow channel

[0050] 43. Elastic sleeve

[0051] 431. Second accommodating cavity

[0052] 44. Suction attachment

[0053] 441, activated carbon;

[0054] 442, carrier disk;

[0055] 5, drive mechanism;

[0056] 6, primary cold disk;

[0057] 7, secondary cold disk;

[0058] 8, tertiary cold disk;

[0059] 9, pre-cooling unit;

[0060] 90, room temperature disk;

[0061] 91, hot end;

[0062] 92, primary cold head;

[0063] 93, secondary cold head. DETAILED DESCRIPTION

[0064] Hereinafter, embodiments of the present application will be described with reference to the accompanying drawings. It is to be understood, however, that these descriptions are merely exemplary and are intended to illustrate the scope of the present application, not to limit it. In the following detailed description of the embodiments of the present application, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present application. However, it will be apparent to one skilled in the art that the embodiments of the present application can be practiced without these specific details. In other instances, well-known structures and

[0065] The terms used herein are merely used to describe specific embodiments, and are not intended to limit the present application. The terms "include" and "have" and the like used herein indicate the presence of the described features, steps, operations, and / or components, but do not preclude the presence or addition of one or more other features, steps, operations, or components.

[0066] All terms used herein, including technical and scientific terms, have the same meanings as those generally understood by those skilled in the art, unless otherwise defined. It should be noted that the terms used herein should be interpreted as having meanings consistent with the context of the present specification, and should not be interpreted in an idealized or excessively formal manner.

[0067] In the case of using expressions similar to "at least one of A, B, and C, etc.", it is generally construed that the meaning of the expression is understood by one of ordinary skill in the art (for example, "a system having at least one of A, B, and C" should include but is not limited to a system having A alone, a system having B alone, a system having C alone, a system having A and B together, a system having A and C together, a system having B and C together, and / or a system having A, B, and C together, etc.).

[0068] Figure 1 is a perspective view of a heat exchanger for a dilution refrigerator provided by an embodiment of the present application, Figure 2 is a perspective view of a heat exchange unit of the heat exchanger, Figure 3 is a sectional view of the heat exchange unit, Figure 4 is a sectional view of the heat exchange unit.

[0069] An embodiment of the present application provides a heat exchanger for a dilution refrigerator, as shown in Figures 1 to 4 which comprises a plurality of heat exchange units 1 connected in sequence, each of the heat exchange units 1 comprising a heat conducting member 11, two cover bodies 12 and a filling body 13. The two cover bodies 12 are respectively arranged on two sides of the heat conducting member 11 to define a first chamber and a second chamber, the first chamber containing flowing 3 He solution, and the second chamber containing flowing mixture of 3 He solution and 4 He solution, so that the 3 He solution and the mixture exchange heat through the heat conducting member 11. The filling body 13 is arranged in the first chamber and the second chamber, and the filling body 13 has a first pore system formed inside, which is adapted to increase the heat exchange area of the 3 He solution and the mixture. The filling body 13 also has a second pore system formed inside, which is adapted to increase the heat exchange area while increasing the penetration depth of the 3 He solution and the mixture into the filling body 13.

[0070] In such an embodiment, the heat conducting member 11 and the two cover bodies 12 define the first chamber and the second chamber, and when the 3 He solution and the mixture flow through the filling body 13, they exchange heat with the filling body 13, and the filling body 13 on both sides of the heat conducting member 11 further exchanges heat through the heat conducting member 11 to achieve the cooling of the 3 He solution by the mixture. The filling body 13 has a porous structure and has two pore systems, the first pore system mainly increases the heat exchange area, and the second pore system also has a certain effect on increasing the heat exchange area, but the second pore system mainly increases the penetration depth of the 3 He solution and the mixture into the filling body 13. Through the cooperation of the second pore system and the first pore system, the filling body 13 can increase the volume by increasing the thickness, thereby further increasing the heat exchange area, and the problem of the 3 He solution and the mixture being difficult to penetrate can be avoided, and the problem of the volume of the filling body 13 and the heat exchange unit 1 being too large due to the simple increase of the bottom area, occupying too much arrangement space and significantly increasing the use amount of the 3 He solution can be avoided.

[0071] In addition, the diameter of the first hole system can be further reduced, and the hole density can be increased, and due to the auxiliary permeation of the second hole system, the problems of increased flow resistance and difficult permeation can be effectively alleviated.

[0072] In some embodiments, the first hole system includes a plurality of heat exchange holes, and the second hole system includes a plurality of permeation holes, and the diameter of the permeation holes is greater than the diameter of the heat exchange holes.

[0073] In such embodiments, due to the larger diameter of the permeation holes, the flow resistance of the fluid is smaller, so that the working medium (He solution and mixed solution) can deeply penetrate into the main channels inside the filler 13. 3 The heat exchange holes have a small diameter, and a large number of micro-porous channels with a large surface area can be formed in a unit volume. By arranging two hole systems with different diameters, the trade-off relationship between the heat exchange area and the penetration depth is broken. The large-diameter permeation holes ensure permeability, making it possible to increase the thickness of the filler 13, and the small-diameter heat exchange holes efficiently provide the required heat exchange area in the entire volume activated by the permeation holes.

[0074] According to an embodiment of the present application, the filler 13 includes a sintered body made of nano-silver powder.

[0075] In such embodiments, the thermal conductivity of silver is high, which is significantly higher than that of other thermal conductive materials in the temperature range of several k (kelvin) to several tens of mk (millikelvin). Moreover, the sintering process can form a large number of heat exchange holes between silver particles, which constitute the first hole system. The sintered body made of nano-silver powder has both a porous heat exchange structure and a high thermal conductivity, effectively improving the heat exchange efficiency between the He solution and the mixed solution and the filler 13. 3 He solution and mixed solution and the filler 13.

[0076] In some embodiments, as shown in Figure 1 The first chambers of adjacent heat exchange units 1 are connected, and the second chambers of adjacent heat exchange units 1 are connected, wherein the connected first chambers are used as the hot side of the heat exchanger, and the connected second chambers are used as the cold side of the heat exchanger.

[0077] In such embodiments, a plurality of heat exchange units 1 are connected in series, and the 3 The He solution flows into one end of the hot side flow channel and sequentially flows through the first chambers of the series-connected heat exchange units 1. At the same time, the mixed solution with a lower temperature flows into the other end of the cold side flow channel and flows through the second chambers of the series-connected heat exchange units 1 in the opposite direction (opposite to the flow direction of the He solution). 3 The He solution flows into one end of the hot side flow channel and sequentially flows through the first chambers of the series-connected heat exchange units 1. At the same time, the mixed solution with a lower temperature flows into the other end of the cold side flow channel and flows through the second chambers of the series-connected heat exchange units 1 in the opposite direction (opposite to the flow direction of the He solution). 3The He solution exchanges heat with each heat exchange unit 1 through the heat conducting member 11 and the filling body 13. In this way, a more uniform temperature gradient can be formed and maintained in the heat exchanger, so that a higher average heat exchange temperature difference and heat exchange efficiency can be obtained.

[0078] Figure 5 is a flow chart of a manufacturing method of the heat exchanger for a dilution refrigerator according to an embodiment of the present application.

[0079] An embodiment of the present application further provides a manufacturing method of a heat exchanger, for manufacturing the heat exchanger in any of the above embodiments, as shown in the figure, the method comprises steps S1-S7. Figure 5

[0080] Step S1, using a 3D printing forming technology to prepare a second pore system skeleton.

[0081] Step S2, placing the second pore system skeleton into a mold, filling the mold with nano-silver powder to cover the second pore system skeleton and compacting into a block.

[0082] Step S3, removing the second pore system skeleton using a solvent, leaving a nano-silver powder block.

[0083] Step S4, firing the nano-silver powder block to form a sintered body with a first pore system and a second pore system.

[0084] Step S5, repeating steps S1-S4 to prepare a plurality of sintered bodies, processing a plurality of heat conducting members 11 and a plurality of cover bodies 12.

[0085] Step S6, placing the sintered body into the first and second chambers and sealing them to obtain a plurality of heat exchange units 1.

[0086] Step S7, connecting the plurality of heat exchange units 1 through pipes.

[0087] In such an embodiment, a three-dimensional skeleton structure with macroscopic morphology and spatial distribution of seepage pores is prepared using a 3D printing forming technology with a removable material. Then the three-dimensional skeleton structure is placed in a mold, the shape of the mold is approximately the same as the combined shape of the cover body 12 and the heat conducting member 11, and after filling with nano-silver powder, it is compacted to obtain a nano-silver powder block with a second pore system skeleton inside. Then the second pore system skeleton is removed using a solvent to obtain a nano-silver powder block with a second pore system. Then firing is performed to form a first pore system inside the nano-silver powder block. In this way, the problem of high processing difficulty in traditional pore forming process is effectively solved, and the production cost is reduced.

[0088] In some optional embodiments, the 3D printing forming technology includes but is not limited to hot extrusion or photocuring, and the corresponding material of the second pore system skeleton is plastic or resin, and the removal solvent can be limonene.

[0089] ​In some alternative embodiments, the heat-conducting element 11 and the cover 12 are manufactured by casting or wire cutting methods, and the heat-conducting element 11 is preferably made of oxygen-free copper.

[0090] In some alternative embodiments, the heat-conducting element 11 and the cover 12 are connected by laser welding or indium sealing to ensure sealing performance in extremely low temperature environments.

[0091] In some alternative embodiments, the pipe connecting the heat exchange unit 1 is a stainless steel pipe.

[0092] Figure 6 This is a three-dimensional structural diagram of the heat exchanger for a dilution refrigerator, after connecting the mixing chamber and the evaporation chamber, according to an embodiment of the present invention. Figure 7 This is a plan view of the heat exchanger for a dilution refrigerator provided in an embodiment of the present invention, after connecting the mixing chamber and the evaporation chamber.

[0093] Embodiments of the present invention also provide a dilution refrigeration machine, such as Figure 6 and Figure 7 The diagram shows a mixing chamber 2, an evaporator section, and a heat exchanger for a dilution refrigerator as described in any of the above embodiments. The mixing chamber 2 stores materials located in the upper layer. 3 He condensed phase and the lower layer 3 He dilution phase, 3 The condensed phase of He was configured in response to 3 He dilution phase 3 The concentration of He decreased, towards 3 He dilution phase compensation 3 He simultaneously absorbs ambient heat for cooling. The evaporator section is connected to the mixing chamber 2 to store at least a portion of the heat. 3 He dilutes the phase, and the evaporation section is configured to... 3 He dilution phase 3 He evaporates and is then condensed to form... 3 He solution flow back 3 The concentrated phase is used to form a circulating dilution refrigeration system with mixing chamber 2. A heat exchanger is located between mixing chamber 2 and the evaporator section, and has a hot side and a cold side; the hot side is suitable for... 3 He solution flow back 3 He concentrated phase, cold side suitable for connecting mixing chamber 2 and evaporation section 3 He is diluted phase to exchange heat with the hot side.

[0094] In this embodiment, the mixing chamber 2 stores 3 He condensed phase (i.e.) 3 He solution) and 3 He dilution phase (i.e.) 3 He solution and 4 (a mixture of He solution), in the evaporation section3 He is evaporated to form 3 He vapor, at which time the 3 He concentration in the evaporation section decreases, and the 3 He concentrated phase moves toward 3 He dilute phase compensates 3 He absorbs heat to effect dilution refrigeration. 3 He vapor is liquefied by cooling and enters the hot side of the heat exchanger (i.e., the first chamber in sequence), and exchanges heat with the 3 He dilute phase in the cold side (i.e., the second chamber in sequence) in succession, and finally returns to the 3 He concentrated phase in the mixing chamber 2. By setting the heat exchanger as in any of the above embodiments, not only is the heat exchange efficiency effectively increased, but also the occupation of excessive horizontal space is avoided, and the 3 He usage is reduced.

[0095] Figure 8 is a plan view of a dilution refrigerator according to an embodiment of the present application.

[0096] According to an embodiment of the present application, as Figure 8 shown, the evaporation section includes an evaporation chamber 3 and 3 He internal circulation device, the evaporation chamber 3 is in communication with the mixing chamber 2 through the cold side, to store at least a portion of 3 He dilute phase, suitable for evaporating 3 He in the dilute phase to produce 3 He vapor. 3 He vapor. 3 He internal circulation device is configured to absorb 3 He vapor in the evaporation chamber 3 in response to the device temperature being in the second temperature zone, and release 3 He vapor in response to the device temperature being in the first temperature zone, 3 He vapor is condensed by heat release and enters the hot side of the heat exchanger.

[0097] In such an embodiment, when the evaporation chamber 3 reaches a preset temperature, about 0.6-1k, generally 0.8k, at which time 3 He has a significantly higher saturated vapor pressure than 4 He, and is therefore selectively evaporated. The 3 He concentration in the evaporation chamber 3 decreases, and the 3 He dilute phase in the mixing chamber 2 is supplemented to the evaporation chamber 3 through the cold side of the heat exchanger 3 He. The 3 He vapor evaporated is drawn out by the 3 He internal circulation device, and is released to the mixing chamber 2 under the condition that the temperature does not exceed the first temperature zone, to reduce 3He steam carries heat.

[0098] In some alternative embodiments, the released 3 He steam first exchanges heat with the 3 He dilute phase in the evaporation chamber 3, and the process 3 He steam exchanges heat through a pipe penetrating the evaporation chamber 3, without directly contacting 3 He dilute phase. After the preliminary heat exchange, 3 He steam enters a secondary heat exchange pipe, which is arranged between the heat exchanger and the evaporation chamber 3, and is configured as a double-layer pipe, 3 He dilute phase flows in the inner layer, 3 He steam flows in the outer layer, and a capillary structure can be arranged in the outer layer to assist 3 He steam to liquefy, thereby entering the hot side of the heat exchanger.

[0099] In some alternative embodiments, the secondary heat exchange pipe is configured as a spiral double-layer pipe extending in the vertical direction.

[0100] Figure 9 is a perspective view of a dilution refrigerator provided by another embodiment of the present application.

[0101] In some other embodiments, as shown in Figure 9 , in the dilution refrigerator, the heat exchanger can also adopt other heat exchange structures, as long as it can achieve the heat exchange between 3 He solution and 3 He dilute phase flowing out of the mixing chamber 2.

[0102] Figure 10 is a perspective view of a dilution refrigerator provided by an embodiment of the present application. 3 He internal circulation device, Figure 11 is a perspective view of a dilution refrigerator provided by an embodiment of the present application. 3 He internal circulation device.

[0103] In some embodiments, as shown in Figure 8 , Figure 10 and Figure 11 , 3 He internal circulation device includes at least one pair of circulation bodies 4 and a driving mechanism 5, the at least one pair of circulation bodies 4 are arranged between a first cold plate 6 and a second cold plate 7 which are spaced apart in the vertical direction, the temperature of the first cold plate 6 is in a first temperature zone, and the temperature of the second cold plate 7 is in a second temperature zone, each circulation body 4 in each pair of circulation bodies 4 has a downward movement to contact the second cold plate 7 and be cooled to the second temperature zone, so as to adsorb 3The first state of He vapor, and its upward movement to contact with the primary cold plate 6 and rise to the first temperature zone, so as to be released into the mixing chamber 2. 3 The second state of He vapor. The drive mechanism 5 is adapted to drive two of the two circulating bodies 4 in each pair of circulating bodies 4 to move vertically to switch between the first and second states, and to keep the two circulating bodies 4 in different states to form... 3 He steam internal circulation path.

[0104] In such an implementation, with 3 The internal circulation device includes a pair of circulation bodies 4 (i.e., two). For example, one circulation body 4 is in contact with the secondary cold plate 7, continuously adsorbing the generated... 3 He vapor, another circulating body 4 comes into contact with the primary cooling plate 6. After a period of time, the drive mechanism 5 is activated, causing one circulating body 4 to detach from the secondary cooling plate 7 and come into contact with the primary cooling plate 6, releasing it into the mixing chamber 2. 3 Meanwhile, He vapor is released, and at the same time, another circulating unit 4 detaches from the primary cold plate 6 and comes into contact with the secondary cold plate 7, adsorbing the generated vapor. 3 He steam. After a period of time, the drive mechanism 5 drives the two circulating bodies 4 to alternate again, and so on in a continuous cycle, effectively shortening the time. 3 The circulation path between the evaporation chamber 3 and the mixing chamber 2 prevents external heat from leaking into the low-temperature zone of the dilution refrigeration unit.

[0105] More specifically, the temperature range of the first temperature zone is approximately 30K-50K, and the temperature range of the second temperature zone is approximately 3K-4K. When the main body of the circulation system 4 is in the first temperature zone, it... 3 He vapor's adsorption capacity decreases, thus it is released outwards. 3 When He steam, the main body of the circulation system 4 is in the second temperature zone, for 3 The adsorption capacity of He vapor is significantly increased, thus enabling effective adsorption. 3 He steam. Released 3 After heat exchange, the He vapor cools down and condenses to form 3 The He solution eventually flows back to mixing chamber 2, while the solution in evaporation chamber 3... 3 He's concentration decreased due to evaporation, prompting the mixing chamber 2 to... 3 He replenishes the evaporation chamber 3, thus forming a complete circulation path. During this circulation process, 3 He vapor can only reach temperatures of 30K-50K under standard atmospheric pressure. 3 He has a condensation temperature of approximately 3.2 K, and only a small amount of heat needs to be released to complete the liquefaction and reflux.

[0106] Compared to traditional 3 He-cycle scheme, 3He vapor is drawn to room temperature (approximately 300 K) by a pump unit, and requires pressurization and multi-stage heat exchange for cooling to complete liquefaction. The present invention provides... 3 The internal circulation device effectively improves circulation efficiency and significantly reduces heat leakage.

[0107] Figure 12 This is provided by the embodiments of the present invention. 3 He internal circulation device circulation main body three-dimensional structure diagram Figure 13 This is the dilution refrigeration machine provided in the embodiments of the present invention. 3 Cross-sectional perspective view of the main circulation body of the He internal circulation device. Figure 14 This is the dilution refrigeration machine provided in the embodiments of the present invention. 3 Partial cross-sectional view of the main circulation body of the He internal circulation device. Figure 15 yes Figure 13 Three-dimensional structural diagram after removing the elastic sleeve and valve body.

[0108] According to embodiments of the present invention, such as Figure 10 , Figure 12 and Figure 13 As shown, the circulation body 4 includes a movable tube 41, two heat-conducting valve seats 42, and two elastic sleeves 43. The movable tube 41 extends vertically and is connected to the drive mechanism 5. The movable tube 41 has a design suitable for accommodating... 3 The first containment cavity 411 for He vapor. Two heat-conducting valve seats 42 are located at the two openings of the movable tube 41, and at least partially extend into the movable tube 41. The heat-conducting valve seats 42 have a supply... 3 He steam flow channel 423; two elastic sleeves 43 are adapted to connect movable tube body 41 and heat conduction valve seat 42, the elastic sleeves 43, heat conduction valve seat 42 and movable tube body 41 define a second receiving cavity 431 communicating with the flow channel 423, the movable tube body 41 is configured to compress one of the elastic sleeves 43 under the drive of the drive mechanism 5, so that the second receiving cavity 431 on the same side as the elastic sleeve 43 communicates with the first receiving cavity 411.

[0109] In such an implementation, such as Figure 12 As shown, the movable tube 41 is constructed as a hollow tube extending vertically, and two heat-conducting valve seats 42 are disposed at the openings at the upper and lower ends of the movable tube 41 (and...). Figure 12 (The upper and lower ends are consistent), and the two elastic sleeves 43 are used to connect each heat-conducting valve seat 42 to the movable tube body 41. In other words, the movable tube body 41 is suspended between the two heat-conducting valve seats 42 with the support of the two elastic sleeves 43, and has no direct contact with the heat-conducting valve seats 42.

[0110] When the movable tube 41 begins to move under the drive of the drive mechanism 5, the movable tube 41, the elastic sleeve 43, and the heat-conducting valve seat 42 initially move synchronously upwards and downwards, at which point the elastic sleeve 43 hardly deforms. When the heat-conducting valve seat 42 moves to abut against the primary cold plate 6 / secondary cold plate 7, the movable tube 41 begins to compress the elastic sleeve 43 to gradually approach the heat-conducting valve seat 42, and the second receiving cavity 431 subsequently connects with the first receiving cavity 411. As the movable tube 41 continues to move until it contacts the heat-conducting valve seat 42, the primary cold plate 6 / secondary cold plate 7 begins to exchange heat with the movable tube 41 through the heat-conducting valve seat 42. When the temperature of the movable tube 41 reaches the first temperature zone / second temperature zone... 3 He vapor is released from the first receiving chamber 411 and flows sequentially through the second receiving chamber 431 and the flow channel 423 to the mixing chamber 2, or it is drawn into the first receiving chamber 411 from the evaporation chamber 3 sequentially through the flow channel 423 and the second receiving chamber 431.

[0111] Further according to embodiments of the present invention, such as Figure 14 As shown, each circulation body 4 also includes an adsorption element 44 disposed within the first receiving cavity 411 and configured to release under conditions of a first temperature zone. 3 He vapor, and adsorption in the second temperature zone 3 He steam.

[0112] In this implementation, when the circulating body 4 comes into contact with the secondary cold plate 7 and cools down to the second temperature zone, the temperature of the adsorbent 44 subsequently drops to its high-efficiency adsorption temperature, thus affecting... 3 The adsorption capacity of He vapor increased significantly, and the adsorption capacity from evaporation chamber 3 was also increased. 3 He vapor. When the circulating body 4 comes into contact with the primary cold plate 6 and heats up to the first temperature zone, the temperature of the adsorbent 44 rises accordingly, affecting... 3 The adsorption capacity of helium vapor decreases sharply, and the previously adsorbed... 3 He vapor is released and flows into mixing chamber 2. This utilizes the adsorption capacity of adsorbent 44 to transport vapor as temperature changes. 3 He steam avoids the vibration effects present when using pump sets, while temperature changes are limited to between the first and second temperature zones, i.e., the low-temperature zone of the dilution chiller, thus avoiding the input of ambient heat.

[0113] In some alternative embodiments, such as Figure 13 and Figure 14As shown, each heat-conducting valve seat 42 includes a heat-conducting disk 421 and a valve body 422. A flow channel 423 is formed in the heat-conducting disk 421, and an elastic sleeve 43 is connected between the heat-conducting disk 421 and the movable tube 41. The valve body 422 extends from the heat-conducting disk 421 into the movable tube 41 and is configured to reciprocate axially relative to the movable tube 41 to close or open an opening on the same side as the valve body 422.

[0114] In this embodiment, the heat-conducting plate 421 serves as the heat transfer medium between the primary cold plate 6 / secondary cold plate 7 and the heat-conducting element 11. The valve body 422 extends into the movable tube 41. When the movable tube 41 and the heat-conducting plate 421 move closer together, the valve body 422 disengages from the inner wall of the movable tube 41, connecting the first receiving cavity 411 and the second receiving cavity 431. When the movable tube 41 and the heat-conducting plate 421 move away from each other until the valve body 422 re-contacts the inner wall of the movable tube 41, the connection between the first receiving cavity 411 and the second receiving cavity 431 is severed.

[0115] According to embodiments of the present invention, such as Figure 15 As shown, the movable tube 41 has a large-diameter section 412 and small-diameter sections 413 located at both ends of the large-diameter section 412. The diameter of the large-diameter section 412 is approximately the same as the diameter of the heat-conducting plate 421 and the diameter of the elastic sleeve 43, and is used to compress the elastic sleeve 43. The small-diameter section 413 extends into the elastic sleeve 43 and is used to contact the heat-conducting plate 421. The valve body 422 extends into the small-diameter section 413. Multiple through holes 4131 are provided on the side wall of the small-diameter section 413. The axis of the through holes 4131 is perpendicular to the vertical direction to allow the small-diameter section 413 to contact the heat-conducting plate 421. 3 He vapor flows from the first receiving cavity 411 to the second receiving cavity 431.

[0116] In some alternative embodiments, such as Figure 15 As shown, the adsorbent 44 includes activated carbon 441 and a support plate 442. The activated carbon 441 is suitable for adsorption or release. 3 He steam, the support plate 442 is installed on the inner wall of the movable tube 41, and is suitable for holding activated carbon 441.

[0117] In this embodiment, activated carbon 441 has a high specific surface area and microporous structure, and is able to respond to temperature changes from the first temperature zone to the second temperature zone. 3 He vapor is adsorbed and released. Holding it in the support plate 442 can prevent the particles of activated carbon 441 from leaking into the second receiving chamber 431 and the outside of the circulation body 4, or from blocking the flow channel 423.

[0118] In some optional embodiments, two support disks 442 are provided, with activated carbon 441 sandwiched between the two support disks 442. The support disks 442 are threadedly connected to the inner wall of the movable tube 41.

[0119] In some alternative embodiments, the heat transfer plate 421, the movable tube 41, and the support plate 442 are made of oxygen-free copper to efficiently and quickly transfer heat between the activated carbon 441 and the primary cold plate 6 / secondary cold plate 7, shortening the vacuum period that occurs during device operation due to the heating / cooling process.

[0120] In some alternative embodiments, the support plate 442 is configured as a porous structure with pore sizes smaller than the particle size of the activated carbon 441, so as to allow for the holding of the activated carbon 441 while allowing for the holding of the activated carbon 441. 3 He steam passed through.

[0121] In this implementation, because the pore size of the support plate 442 is smaller than the particle size of the activated carbon 441, it forms an effective physical sieve, reliably confining all the activated carbon 441 particles and preventing them from moving or leaking under any circumstances (such as vibration, airflow impact, etc.), thereby ensuring operational stability. Furthermore, the support plate 442 also allows... 3 He vapor passes through and comes into full contact with activated carbon 441 without the need for specially designed channels, and the low flow resistance is beneficial for improving adsorption / release efficiency.

[0122] In some alternative embodiments, the support plate 442 is made of foamed stainless steel, which meets the usage requirements while providing high structural rigidity and strength.

[0123] In some optional embodiments, a stainless steel sleeve is fitted over the active tube 41 to ensure that the temperature of the adsorption element 44 changes only under the influence of the primary cold plate 6 and the secondary cold plate 7, thereby reducing interference.

[0124] In some other embodiments, such as Figure 16 As shown, 3 The internal circulation device includes two pairs of circulation bodies 4, and the two pairs of circulation bodies 4 are activated at a preset time interval.

[0125] In this implementation, when the circulation body 4 switches states under the drive of the drive mechanism 5, the temperature of the adsorption element 44 in the moving tube 41 needs a certain period of time to reach the first temperature zone / second temperature zone. During this process, the adsorption element 44 will neither adsorb nor absorb... 3 He will not release steam. 3He vapor causes a brief shutdown (or standby) time after the switching state. This is addressed by adding another pair of circulating units 4, which are started at a preset time interval from the previous pair. When the previous pair of circulating units 4 switches state and enters the shutdown (or standby) time, the additional pair of circulating units 4 continues adsorption and release operations, preventing the entire dilution refrigeration unit from... 3 The He loop is interrupted.

[0126] According to an embodiment of the present invention, the two loop bodies 4 in each pair of loop bodies 4 switch states every cycle duration, and the preset time interval is half a cycle duration.

[0127] In this implementation, by setting the preset time interval to half a working cycle duration, not only can the two pairs of cyclic main bodies 4 cover each other's downtime (or standby time), but the stability of long-term operation can also be improved. If the preset time interval is set to 1 / 3 or 1 / 4 of a cycle duration, although it can operate normally in a short time, after multiple cycles, the downtime (or standby time) of the two pairs of cyclic main bodies 4 will still overlap.

[0128] In some alternative embodiments, the drive mechanism 5 includes multiple cylinders and a controller, each cylinder driving a circulating body 4, and the controller controlling the corresponding cylinder action and the timing of the action.

[0129] In some alternative embodiments, such as Figure 9 As shown, the above-mentioned dilution refrigeration unit also includes a multi-stage cold plate and a pre-cooling unit 9. The multi-stage cold plate includes a first-stage cold plate 6, a second-stage cold plate 7, and a third-stage cold plate 8 arranged vertically at intervals. The circulation body 4 is disposed between the first-stage cold plate 6 and the second-stage cold plate 7, and the mixing chamber 2 is disposed on the third-stage cold plate 8. The pre-cooling unit 9 is suitable for cooling the first-stage cold plate 6 and the second-stage cold plate 7 to the first temperature zone and the second temperature zone, respectively.

[0130] In this embodiment, the precooling unit 9 includes a hot end 91, a primary cold head 92, and a secondary cold head 93. The hot end 91 is disposed on the room temperature plate 90 (temperature approximately 300K), and the primary cold head 92 is disposed between the room temperature plate 90 and the primary cold plate 6. The secondary cold head 93 is disposed between the primary cold plate 6 and the secondary cold plate 7. The cooling power of the primary cold head 92 is higher than that of the secondary cold head 93, so as to cool the primary cold plate 6 and the secondary cold plate 7 to the first temperature zone and the second temperature zone, respectively. At least one tertiary cold plate 8 is provided in the mixing chamber 2, and one can also be provided in the evaporation chamber 3 and the heat exchanger.

[0131] Those skilled in the art will appreciate that features recited in the various embodiments of the present application can be combined and / or interchanged, even if this is not explicitly stated in the present application. In particular, features recited in the various embodiments of the present application can be combined and / or interchanged, without departing from the spirit and teachings of the present application. All such combinations and / or interchanges are within the scope of the present application.

[0132] The above describes embodiments of the present application. However, these embodiments are merely for illustrative purposes and are not intended to limit the scope of the present application. Although each embodiment is described above separately, this does not mean that the measures in each embodiment cannot be used advantageously in combination. Without departing from the scope of the present application, those skilled in the art can make various substitutions and modifications, which should all fall within the scope of the present application.

Claims

1. A heat exchanger for a dilution refrigeration machine, characterized in that, It includes multiple heat exchange units connected in sequence, wherein the heat exchange unit includes: Thermal conductive components; Two enclosures are respectively placed on both sides of the heat-conducting component to define a first chamber and a second chamber, wherein the first chamber contains flowing... 3 He solution, with flow in the second chamber. 3 He solution and 4 A mixture of He solutions, to make the 3 The He solution and the mixture exchange heat through the heat-conducting element; A filler body is disposed in the first chamber and the second chamber, and a first pore system is formed inside the filler body to facilitate increasing the filling depth. 3 The heat exchange area between the He solution and the mixture is further enhanced by a second pore system formed inside the filler, which is suitable for increasing the heat exchange area while simultaneously increasing the heat exchange surface area. 3 The depth to which the He solution and the mixture penetrate into the interior of the filler; The first pore system includes multiple heat exchange pores, and the second pore system includes multiple seepage pores, wherein the diameter of the seepage pores is larger than the diameter of the heat exchange pores.

2. The heat exchanger for a dilution refrigerator according to claim 1, characterized in that, The filler comprises a sintered body made of nano-silver powder.

3. The heat exchanger for a dilution refrigerator according to claim 1, characterized in that, The first chambers of adjacent heat exchange units are connected, and the second chambers of adjacent heat exchange units are connected. The first chamber, which is connected to the heat exchanger, serves as the hot side of the heat exchanger, and the second chamber, which is connected to the heat exchanger, serves as the cold side of the heat exchanger.

4. A method for manufacturing a heat exchanger, characterized in that, For manufacturing a heat exchanger for a dilution refrigeration unit according to any one of claims 1-3, comprising: The second porous framework was prepared using 3D printing technology. The second porous framework is placed into a mold, and nano-silver powder is filled into the mold to cover the second porous framework and then compacted into a block. The second porous framework was removed using a solvent, while the silver nanoparticles were retained. The nano-silver powder block is sintered to form a sintered body with a first pore system and a second pore system; Repeat the above steps to prepare multiple sintered bodies, and process multiple heat-conducting components and multiple covers; The sintered body is placed into the first chamber and the second chamber and sealed to obtain multiple heat exchange units; Multiple heat exchange units are connected by pipes.

5. A dilution refrigeration machine, characterized in that, include: The mixing chamber stores the contents located in the upper layer. 3 He condensed phase and the lower layer 3 He dilution phase, the 3 The concentrated phase of He is configured to respond to the aforementioned 3 He dilution phase 3 The concentration of He decreased, towards the 3 He dilution phase compensation 3 He simultaneously absorbs heat from the surrounding environment to cool down; The evaporation section is connected to the mixing chamber to store at least a portion of the mixture. 3 He dilution phase, the evaporation section is configured to dilute the phase. 3 He dilution phase 3 He evaporates and is then condensed to form... 3 He solution flows back to the 3 He concentrated phase, to form a circulating dilution refrigeration with the mixing chamber; The heat exchanger for a dilution refrigerator as described in any one of claims 1-3 is disposed between the mixing chamber and the evaporation section, the heat exchanger comprising a hot side and a cold side, the hot side being adapted to... 3 He solution flows back to the 3 He concentrated phase, the cold side is suitable for connecting the mixing chamber and the evaporation section. 3 He is diluted phase to exchange heat with the hot side.

6. The dilution refrigeration machine according to claim 5, characterized in that, The evaporation section includes: The evaporation chamber, connected to the mixing chamber via the cold side, is used to store at least a portion of the contents. 3 He dilution phase, suitable for diluting the above 3 He dilution phase 3 He evaporates 3 He steam; 3 The internal circulation device is configured to adsorb substances from the evaporation chamber in response to the device temperature being in the second temperature zone. 3 He vapor, and in response to the device temperature being in the first temperature zone, release 3 He steam, the 3 He vapor enters the hot side of the heat exchanger after being condensed and released from heat.

7. The dilution refrigeration machine according to claim 6, characterized in that, The 3 The internal circulation device includes: At least one pair of circulating bodies are disposed between a primary cold plate and a secondary cold plate spaced apart in a vertical direction. The temperature of the primary cold plate is in a first temperature zone, and the temperature of the secondary cold plate is in a second temperature zone. Each circulating body in each pair has the function of moving downward to contact the secondary cold plate and cooling down to the second temperature zone to adsorb substances from the evaporation chamber. 3 The first state of He vapor, and its upward movement to contact the primary cold plate and rise to the first temperature zone for release into the mixing chamber. 3 The second state of He vapor; A drive mechanism is adapted to drive two of the loop bodies in each pair of loop bodies to move vertically to switch between the first state and the second state, and to keep the two loop bodies in different states, thereby constituting a configuration. 3 He steam internal circulation path.

8. The dilution refrigeration machine according to claim 7, characterized in that, The loop body includes: A movable tube, extending vertically and connected to the drive mechanism, is provided with a design suitable for accommodating... 3 The first cavity containing He vapor; Two heat-conducting valve seats are respectively located at two openings of the movable tube body, and at least partially extend into the movable tube body. The heat-conducting valve seats have a heat supply... 3 He's steam flow channel; Two resilient sleeves are adapted to connect the movable tube and the heat-conducting valve seat. The resilient sleeves, the heat-conducting valve seat, and the movable tube define a second receiving cavity communicating with the flow channel. The movable tube is configured to compress one of the resilient sleeves under the drive of the drive mechanism, such that the second receiving cavity on the same side as the resilient sleeve communicates with the first receiving cavity.

9. The dilution refrigeration machine according to claim 8, characterized in that, Each of the circulating bodies further includes an adsorption element disposed within the first receiving cavity and configured to release under conditions of a first temperature zone. 3 He vapor, and adsorption in the second temperature zone 3 He steam.

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