Continuous cryogenic refrigerator

Abstract

The invention discloses a continuous cryogenic refrigerator, and relates to the field of refrigeration. At least two ultralow-temperature refrigeration devices are arranged on the refrigeration platform, continuous refrigeration of the refrigeration platform is achieved through alternate operation of the condensation process and the refrigeration process in the different ultralow-temperature refrigeration devices, meanwhile, the evaporator exchanges heat with the refrigeration platform through the air gap heat switch, and the refrigeration platform is cooled through the air gap heat switch. Friction force between the valve and the pipeline and airflow in the gas flowing process is reduced, and the refrigeration effect is prevented from being reduced due to gas temperature rise.

Description

Technical Field

[0001] The invention relates to the field of refrigeration, and in particular to an ultra-low temperature refrigerator. Background Art

[0002] With the development of space science programs, related research in the fields of deep space exploration and manned space stations has increasingly higher requirements for ultra-low temperatures (<1 K). Adsorption refrigerators are now used instead of traditional mechanical compressors to achieve lower temperature requirements. Chinese patent CN106352592B proposes an adsorption refrigeration system that operates continuously in the normal temperature range. The system consists of two sets of adsorption pumps, evaporators and condensers. The components are interconnected through pipelines. The valve switches on each pipeline are adjusted to realize the function of alternating operation of the two adsorption refrigeration modules, and finally realize continuous adsorption refrigeration. However, the structure of the system is too complicated. On a gas adsorption refrigerator working under high vacuum and extremely low temperature, the temperature will not only affect the mechanical properties of the valve, but installing too many valves on the pipeline will also cause the valve to produce resistance to the flow of airflow, causing the temperature of the airflow to rise, thereby affecting the final refrigeration performance of the refrigerator. Therefore, the above scheme is not suitable for continuous cooling of a gas adsorption refrigerator under ultra-low temperature. Summary of the invention

[0003] The purpose of the present invention is to provide a continuous ultra-low temperature refrigerator to solve the problems existing in the above-mentioned prior art, so that the gas adsorption refrigerator can continuously cool the refrigeration platform and reduce the friction between the gas and the valve and the pipeline during the gas flow process, prevent the gas temperature from rising, and improve the refrigeration effect.

[0004] To achieve the above-mentioned purpose, the present invention provides the following scheme: The present invention provides a continuous ultra-low temperature refrigerator; it includes an ultra-low temperature refrigeration device, the ultra-low temperature refrigeration device includes a refrigeration platform and a refrigeration module for refrigerating the refrigeration platform, at least two refrigeration modules are arranged, any refrigeration module includes an adsorption bed and an evaporator, the adsorption bed and the evaporator are connected through a pump pipe, an adsorption medium is arranged in the adsorption bed, the evaporator and the refrigeration platform are connected through a first air gap thermal switch, all refrigeration modules are connected to the refrigeration platform in parallel, the continuous ultra-low temperature refrigerator also includes a cooling device for cooling the evaporator and the adsorption bed, and the evaporator and the adsorption bed are connected to the cooling device through a second air gap thermal switch and a third air gap thermal switch respectively, and the refrigeration module also includes a heater, and the heater is used to heat the adsorption medium.

[0005] Furthermore, the third air gap thermal switch, the second air gap thermal switch, and the first air gap thermal switch have the same structure, and all three include an air cavity and a heat exchange surface. The heat exchange surface is arranged at both ends of the air cavity and forms a seal on both ends of the air cavity. An air inlet and an air outlet are arranged on the side wall of the air cavity.

[0006] Furthermore, the air cavity is made of thermal insulation material for ultra-low temperature environments, and the heat exchange surface is made of boron nitride-based ceramic composite materials.

[0007] Furthermore, the air inlets of the third air gap thermal switch, the second air gap thermal switch and the first air gap thermal switch are used to communicate with the gas supply device.

[0008] Furthermore, the pump tube is made of stainless steel.

[0009] Furthermore, the heater is an electric heater.

[0010] Furthermore, the cooling device adopts a throttling refrigerator or a GM refrigerator.

[0011] Furthermore, the thermal insulation material adopts a vacuum insulation panel.

[0012] Furthermore, the cooling medium is helium.

[0013] Furthermore, the adsorption medium is activated carbon.

[0014] Compared with the prior art, the present invention has achieved the following technical effects: During the operation of the continuous ultra-low temperature refrigerator, the evaporator in at least one refrigeration module cools the refrigeration platform, and the other refrigeration modules are in the condensation process of the cooling medium. When the refrigeration module in the refrigeration state is about to end the refrigeration, the first air gap thermal switch between the evaporator in the refrigeration module and the refrigeration platform is disconnected, blocking the heat exchange between the evaporator and the refrigeration platform, and entering the condensation process of the cooling medium at the same time. The refrigeration module that has completed the condensation process starts the gasification process and exchanges heat with the refrigeration platform to complete the refrigeration of the refrigeration platform. The above process can be repeated to achieve continuous refrigeration of the refrigeration platform; the evaporator exchanges heat with the refrigeration platform through the air gap thermal switch, reducing the friction between the valve and the pipeline and the airflow during the gas flow process, and avoiding the temperature rise of the gas to reduce the refrigeration effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0016] Figure 1 It is a structural schematic diagram of the cooling medium condensation process in the continuous refrigerator in an embodiment of the present invention; Figure 2 It is a structural schematic diagram of the cooling process of the cooling medium in the continuous refrigerator in an embodiment of the present invention; Figure 3 It is a structural schematic diagram of continuous refrigeration of a continuous refrigerator in an embodiment of the present invention; Figure 4 Schematic diagram of the structure of the air gap thermal switch in the embodiment of the present invention.

[0017] Among them, 1. adsorption bed; 2. pump pipe; 3. evaporator; 4. heater; 5. cooling device; 6. third air gap thermal switch; 7. second air gap thermal switch; 8. first air gap thermal switch; 9. refrigeration platform; 10. air cavity; 11. heat exchange surface; 12. air inlet; 13. air outlet. DETAILED DESCRIPTION

[0018] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0019] The object of the present invention is to provide a continuous ultra-low temperature refrigerator to solve the problems existing in the prior art and enable a gas adsorption refrigerator to continuously and efficiently cool a refrigeration platform.

[0020] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The continuous ultra-low temperature refrigerator includes an ultra-low temperature refrigeration device, which includes a refrigeration platform 9 and a refrigeration module for refrigerating the refrigeration platform 9. At least two refrigeration modules are provided, and any refrigeration module includes an adsorption bed 1 and an evaporator 3. The adsorption bed 1 is connected to the evaporator 3 through a pump pipe 2. An adsorption medium is provided in the adsorption bed 1. The cooling medium adsorbed in the adsorption medium enters the evaporator 3 through the pump pipe 2 after desorption. The evaporator 3 is connected to the refrigeration platform 9 through a first air gap thermal switch 8. All refrigeration modules are connected to the refrigeration platform 9 in parallel. The continuous ultra-low temperature refrigerator also includes a cooling device 5 for cooling the evaporator 3 and the adsorption bed 1, and the evaporator 3 and the adsorption bed 1 are connected to the cooling device 5 through a second air gap thermal switch 7 and a third air gap thermal switch 6 respectively. By opening or closing the first air gap thermal switch 8, the second air gap thermal switch 7, and the third air gap thermal switch 6, heat exchange between the evaporator 3 and the refrigeration platform 9, the evaporator 3 and the cooling device 5, and the adsorption bed 1 and the cooling device 5 can be realized; The reason why at least two refrigeration modules are provided in the technical solution disclosed in the above embodiment is that the state of a single refrigeration module can only be a condensation state or a vaporization refrigeration state, and it is impossible to keep a refrigeration module in a vaporization refrigeration state in contact with the refrigeration platform 9 at all times, so it is impossible to achieve continuous refrigeration of the refrigeration platform 9. For details, please refer to Figure 1 and Figure 2 : exist Figure 1-2 In the embodiment, the cooling medium is preferably helium. Figure 1 The condensation process of helium in the refrigeration module is as follows: in the condensation process of helium, the third air gap heat switch 6 between the adsorption bed 1 and the cooling device 5 is disconnected to cut off the heat exchange between the adsorption bed 1 and the cooling device 5. The cooling device 5 includes but is not limited to one of a throttling refrigerator and a GM refrigerator (Gifford-Mcmahon refrigerator); the adsorption medium in the adsorption bed 1 is heated by the heater 4. After being heated, the adsorption capacity of the adsorption medium in the adsorption bed 1 decreases, so that the helium is accelerated to separate from the adsorption medium and flow to the evaporator 3. Figure 1 The middle arrow indicates the flow direction of the helium after desorption. At this time, the second air gap thermal switch 7 between the evaporator 3 and the cooling device 5 is in a closed state. The cooling device 5 exchanges heat with the helium in the evaporator 3 through the second air gap thermal switch 7 to reduce the temperature of the helium in the evaporator 3, liquefy the helium, and realize the condensation of the helium; the heater 4 includes but is not limited to an infrared heater, an electromagnetic heater or a resistance heater. In the present application, the heater 4 is preferably a resistance heater.

[0022] After the above condensation process, the helium is temporarily stored in the evaporator 3 in a liquid state. Before the refrigeration process begins, first, the heater 4 is turned off, and the third air gap heat switch 6 between the adsorption bed 1 and the cooling device 5 is closed, and then the refrigeration process begins. Figure 2 The process of gasification and refrigeration of helium in the refrigeration module is to cool the adsorption medium in the adsorption bed 1 by the cooling device 5 so that the adsorption medium can recover its adsorption capacity for helium and the adsorption medium can re-adsorb helium. Figure 2 The middle arrow indicates the flow direction of helium during the adsorption process of the adsorption medium, which reduces the pressure in the evaporator 3, lowers the saturation temperature of the helium, and vaporizes the helium to absorb the heat in the evaporator 3, thereby reducing the temperature in the evaporator 3. At this time, the first air gap heat switch 8 between the evaporator 3 and the refrigeration platform 9 is opened, and heat is exchanged between the evaporator 3 and the refrigeration platform 9 through the first air gap heat switch 8, thereby maintaining the refrigeration effect of the refrigeration platform 9. The adsorption medium includes, but is not limited to, one of activated carbon, molecular sieve, and polymer adsorption resin; in the present application, activated carbon is preferred.

[0023] In the above process, the helium adsorption refrigeration device needs to undergo a condensation process and a gasification refrigeration process, so that the helium adsorption refrigeration device can only refrigerate the refrigeration platform 9 intermittently.

[0024] In order to achieve a continuous cooling effect on the refrigeration platform 9, at least two refrigeration modules need to be connected in parallel on the refrigeration platform 9. Figure 3 In the middle, two refrigeration modules are connected in parallel on the refrigeration platform 9, one of which is in the gasification refrigeration process and the other is in the condensation process; When the left refrigeration module is in the condensation process, the third air gap heat switch 6 between the adsorption bed 1 and the cooling device 5 in the left refrigeration module and the first air gap heat switch 8 between the evaporator 3 and the refrigeration platform 9 are disconnected, and the adsorption bed 1 is heated and heated by the heater 4, and the adsorption capacity of the adsorption medium for helium decreases, and the adsorption medium releases helium, and the helium enters the evaporator 3 through the pump pipe 2. In order to reduce the heat exchange between the helium and the external environment, the pump pipe 2 is made of a material with large thermal resistance and low heat leakage, preferably stainless steel; while the heater 4 heats the adsorption bed 1 to release helium, the second air gap heat switch 7 between the evaporator 3 and the cooling device 5 is closed, and the helium is cooled and liquefied under the action of the cooling device 5 to achieve condensation; After the helium in the adsorption medium is completely released, the heater 4 is turned off, the second air gap heat switch 7 between the evaporator 3 and the cooling device 5 is disconnected, the third air gap heat switch 6 between the adsorption bed 1 and the cooling device 5, and the first air gap heat switch 8 between the evaporator 3 and the refrigeration platform 9 are closed, and the cooling device 5 cools down the adsorption medium in the left refrigeration module through the third air gap heat switch 6, so that the adsorption medium in the left refrigeration module recovers the adsorption capacity of helium. As the adsorption medium adsorbs helium, the pressure in the evaporator 3 is reduced, the saturation temperature of helium decreases, and the liquefied helium is gasified, so that the left refrigeration module enters the refrigeration process. At the same time, the right refrigeration module ends the refrigeration of the refrigeration platform 9, closes the first air gap heat switch 8 between the evaporator 3 and the refrigeration platform 9 in the right refrigeration module, disconnects the heat exchange between the evaporator 3 and the refrigeration platform 9 in the right refrigeration module, and performs the condensation process of the left refrigeration module in the above content.

[0025] The left refrigeration module and the right refrigeration module can respectively repeat the above process to achieve continuous refrigeration of the refrigeration platform 9.

[0026] Using air gap heat switch for static heat exchange can effectively avoid the disadvantages of friction between pipes and valves and gas during air flow, which causes the gas temperature to rise and reduces the cooling effect. The structure of the air gap heat switch is as follows: Figure 4As shown, it includes an air cavity 10 and heat exchange surfaces 11 arranged at both ends of the air cavity 10. The adsorption bed 1, the evaporator 3, the cooling device 5 and the refrigeration platform 9 are all provided with contact surfaces that match the shape of the heat exchange surface 11. The contact surface and the heat exchange surface 11 are both made of boron nitride-based ceramic composite materials. During the installation process, the heat exchange surface 11 abuts against the adsorption bed 1, the evaporator 3, the cooling device 5 and the contact surface on the refrigeration platform 9, and the abutting position is insulated by using a heat insulation material in an ultra-low temperature environment to prevent heat leakage during the heat transfer process; Alternatively, through holes matching the shape of the end face of the air cavity 10 are provided on the adsorption bed 1, the evaporator 3, the cooling device 5 and the refrigeration platform 9, and the end of the air cavity 10 is connected to the adsorption bed 1, the evaporator 3, the cooling device 5 and the refrigeration platform 9 through the through holes, and the connection position is sealed with a heat-insulating material for ultra-low temperature environments to prevent heat leakage during heat transfer.

[0027] An air inlet 12 and an air outlet 13 are provided on the side of the air cavity 10. The air inlet 12 is connected to the gas cylinder, and the gas for heat exchange is introduced into the air cavity 10 through the gas cylinder. Considering that the thermal conductivity of helium in an ultra-low temperature environment is good, the gas cylinder is preferably a helium gas cylinder; The air outlet 13 is connected to the vacuum pump. When the refrigeration module is in the condensation process, the vacuum pump draws the air cavity 10 into a vacuum state through the air outlet 13 to isolate the heat exchange between the refrigeration platform 9 and the evaporator 3. When the refrigeration module is in the gasification refrigeration process, helium is introduced into the air cavity 10 through the helium bottle, and the helium is used to realize the heat exchange between the evaporator 3 and the refrigeration platform 9, thereby maintaining the low temperature environment of the refrigeration platform 9.

[0028] In order to prevent the external environment temperature from affecting the temperature of the helium in the air cavity 10 during heat exchange between the evaporator 3 and the refrigeration platform 9, the air cavity 10 is made of heat insulating material; the heat exchange surface 11 is made of boron nitride-based ceramic composite material to ensure smooth heat transfer in an ultra-low temperature environment.

[0029] Adaptive changes made according to actual needs are all within the protection scope of the present invention.

[0030] It should be noted that it is obvious to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be regarded as exemplary and non-restrictive from any point of view, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims are included in the present invention. Any reference numerals in the claims should not be regarded as limiting the claims involved.

[0031] The present invention uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only used to help understand the method and core ideas of the present invention. At the same time, for those skilled in the art, according to the ideas of the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A continuous ultra-low temperature refrigerator, characterized in that: The invention comprises an ultra-low temperature refrigeration device, the ultra-low temperature refrigeration device comprises a refrigeration platform (9) and a refrigeration module for refrigerating the refrigeration platform (9), at least two refrigeration modules are provided, any one of the refrigeration modules comprises an adsorption bed (1) and an evaporator (3), the adsorption bed (1) and the evaporator (3) are connected via a pump pipe (2), an adsorption medium is arranged in the adsorption bed (1), the evaporator (3) and the refrigeration platform (9) are connected via a first air gap thermal switch (8), all the refrigeration modules are connected in parallel to the refrigeration platform (9), the continuous ultra-low temperature refrigerator further comprises a cooling device (5) for cooling the evaporator (3) and the adsorption bed, and the evaporator (3) and the adsorption bed (1) are connected to the cooling device (5) via a second air gap thermal switch (7) and a third air gap thermal switch (6) respectively; the refrigeration module further comprises a heater (4), the heater (4) being used to heat the adsorption medium.

2. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The third air gap thermal switch (6), the second air gap thermal switch (7), and the first air gap thermal switch (8) have the same structure, and all three comprise an air cavity (10) and a heat exchange surface (11); the heat exchange surface (11) is arranged at both ends of the air cavity (10) and forms a seal for both ends of the air cavity (10); and an air inlet (12) and an air outlet (13) are arranged on the side wall of the air cavity (10).

3. The continuous ultra-low temperature refrigerator according to claim 2, characterized in that: The air cavity (10) is made of a heat-insulating material for ultra-low temperature environments, and the heat exchange surface (11) is made of a boron nitride-based ceramic composite material.

4. The continuous ultra-low temperature refrigerator according to claim 2, characterized in that: The air inlets (12) of the third air gap thermal switch (6), the second air gap thermal switch (7), and the first air gap thermal switch (8) are used to communicate with a gas supply device.

5. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The pump tube (2) is made of stainless steel.

6. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The heater (4) is an electric heater.

7. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The cooling device (5) adopts a throttling refrigerator or a GM refrigerator.

8. The continuous ultra-low temperature refrigerator according to claim 3, characterized in that: The thermal insulation material is a vacuum insulation panel.

9. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The cooling medium is helium.

10. The continuous ultra-low temperature refrigerator according to claim 1, characterized in that: The adsorption medium is activated carbon.

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