Distributed flexible cold chain low-temperature system for permanent shadow area of moon

Abstract

The invention provides a distributed flexible cold chain low-temperature system for a lunar permanent shadow region, and belongs to the technical field of low-temperature environment simulation of the lunar permanent shadow region. The problem that in the prior art, the physical property indexes such as the thermal-electrical-optical-desorption characteristic of the lunar soil water-ice simulant are greatly different from the theoretical predicted value of the real lunar soil water-ice is solved. The device comprises a refrigerating machine, a cold trap, a liquid nitrogen storage tank, a vacuum cover, a low-temperature vacuum environment simulator, a sample table, a flexible cold chain and a sample unit, the low-temperature vacuum environment simulator is installed in the vacuum cover, the output end of the liquid nitrogen storage tank is connected with the low-temperature vacuum environment simulator, and the sample table is installed at the bottom of the low-temperature vacuum environment simulator. A plurality of sample units are arranged on the sample table, the output end of the cold trap penetrates through the vacuum cover and is located in the low-temperature vacuum environment simulator, and the cold trap and the sample units are connected with the refrigerating machine through flexible cold chains. The device is mainly used for simulating ice soil substance mining in the environment of the permanent shadow area of the moon.

Description

Technical Field

[0001] The present invention belongs to the technical field of low-temperature environment simulation in the permanent shadow zone of the moon, and in particular relates to a distributed flexible cold chain low-temperature system in the permanent shadow zone of the moon. Background Art

[0002] Since the beginning of the 21st century, humans have proved through long-distance remote sensing that there is natural water in the permanent shadow areas at the north and south poles of the moon, and it exists in the lunar soil profile in the physical form of ice-soil aggregates. Why is there natural water in the ultra-high vacuum conditions of the moon? The scientific mechanism is believed to be due to the following three conditions: first, the extremely low temperature and no light environment in the permanent shadow area provide the cold trap condensation conditions for water substances; second, there must be a thin water molecule injection flow from the world; third, physical effects such as cold trap capture, adsorption deposition and cold end migration occur between water molecules and lunar soil particles.

[0003] Evidence from planetary science and remote sensing exploration shows that the lowest temperature in the permanent shadows of the lunar north and south poles can reach about 10-30K, and the atmospheric pressure on the lunar surface is of the order of 10-10Pa. Such extreme low temperature and vacuum conditions far exceed the research limits of the Earth's permafrost and conventional water material science. Under the low temperature and vacuum coupling conditions in the permanent shadows of the moon, complex physical effects such as cold trap capture, adsorption deposition, and cold end migration may occur between the dilute water molecules originating from global free diffusion and the lunar soil particles, thus forming stable ice-soil aggregates. Due to the limitations of deep space exploration capabilities, humans have not yet obtained field sampling and detailed investigation evidence of lunar soil water ice materials. The origin and evolution mechanism of ice-soil materials in the permanent shadows of the moon, as well as the influence of environmental-material factors on the comprehensive physical properties of ice-soil aggregates, are still unclear.

[0004] In order to meet the major needs of scientific investigation, resource mining and utilization of ice-soil materials in the permanent shadow area of ​​the moon, it is urgent to solve basic problems such as simulation of lunar soil water ice materials, comprehensive physical property testing and characterization of lunar soil water ice. The existing technology uses three methods, namely, normal pressure water frozen ice, low temperature ice mixed soil, and normal pressure steam condensation ice, which can basically meet the envelope simulation and engineering verification of the mechanical harshness of lunar soil water ice. However, the preparation method and process conditions of the simulant are less consistent with the scientific mechanism of the real formation and evolution mechanism of lunar soil water ice, resulting in a large gap between the physical properties of lunar soil water ice simulants such as thermal-electrical-optical-desorption characteristics and the theoretical predicted values ​​of real lunar soil water ice. Summary of the invention

[0005] In view of this, the present invention aims to propose a distributed flexible cold chain cryogenic system for the permanent shadow zone of the moon, so as to solve the problem that the existing preparation methods and process conditions of ice-soil material simulants in the permanent shadow zone of the moon are not in line with the scientific mechanism of the actual formation and evolution mechanism of lunar soil water ice, resulting in a large gap between the physical properties such as thermal-electrical-optical-desorption characteristics of lunar soil water ice simulants and the theoretical predicted values ​​of real lunar soil water ice.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] A distributed flexible cold chain low-temperature system in a permanent shadow area of ​​the moon comprises a refrigerator, a cold trap, a liquid nitrogen storage tank, a vacuum cover, a cryogenic vacuum environment simulator, a sample stage, a flexible cold chain and a sample unit. The cryogenic vacuum environment simulator is installed in the vacuum cover, the output end of the liquid nitrogen storage tank is connected to the cryogenic vacuum environment simulator, the sample stage is installed at the bottom of the cryogenic vacuum environment simulator, a plurality of sample units are arranged on the sample stage, a cold trap is installed above the vacuum cover, the output end of the cold trap passes through the vacuum cover and is located in the cryogenic vacuum environment simulator, and the cold trap and a plurality of sample units are connected to the refrigerator through a flexible cold chain.

[0008] Furthermore, a stop valve, a liquid nitrogen pump and a throttle valve are sequentially provided on the pipeline between the liquid nitrogen storage tank and the low-temperature vacuum environment simulator along the liquid nitrogen delivery direction.

[0009] Furthermore, a heat-insulating support is installed below the sample stage.

[0010] Furthermore, a composite variable-density multi-layer insulation component is installed on the outside of the low-temperature vacuum environment simulator.

[0011] Furthermore, the composite variable density multi-layer insulation component includes a variable density layer and a polyurethane foam unit. The polyurethane foam unit is installed on the outer wall surface of the low-temperature vacuum environment simulator, and the variable density layer is installed outside the polyurethane foam unit.

[0012] Furthermore, the inner wall surface of the low-temperature vacuum environment simulator is coated with a high-emissivity coating.

[0013] Furthermore, the vacuum cover is connected to the low-temperature vacuum environment simulator via a thin-walled thermal bridge connector.

[0014] Furthermore, the thin-walled thermal bridge connector includes an outer thin-walled tube support, an inner thin-walled tube support and a room temperature connector, the outer thin-walled tube support is installed on the outside of the vacuum cover, the inner thin-walled tube support is installed on the outside of the low-temperature vacuum environment simulator, the inner thin-walled tube support is installed inside the outer thin-walled tube support, and a room temperature connector is installed between the inner thin-walled tube support and the outer thin-walled tube support.

[0015] Furthermore, the head of the refrigerator is connected to the cold storage unit, one end of each flexible cold chain connected to the sample unit is connected to the cold storage unit, a temperature control unit and a heat switch are provided between each flexible cold chain and the sample unit, the sample unit is connected to the flexible cold chain through a connecting base, an insulating layer is provided on the outside of the sample unit, a high specific heat cold storage material is provided on the inside of the insulating layer, and heaters are installed on both ends of the high specific heat cold storage material.

[0016] Furthermore, a radiation shield is provided between the vacuum cover and the low-temperature vacuum environment simulator.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention adopts a mechanical refrigerator to replace the traditional liquid nitrogen cooling method as the low-temperature cooling source of the permanent shadow area environment, which can reduce the operating cost of the instrument.

[0019] 2. The present invention combines the insulation technology with the cold transfer method to smoothly cool the cavity to the set temperature, thereby meeting the requirement of cavity temperature uniformity.

[0020] 3. The present invention adopts a composite variable-density multi-layer insulation component to reduce the heat leakage and thermal interference of the room temperature environment to the low-temperature vacuum environment simulator.

[0021] 4. The present invention provides a highly efficient heat-insulating material such as polyurethane foam that is insensitive to vacuum between the vacuum cover and the low-temperature vacuum environment simulator, which is used for efficient heat insulation in the event of an emergency such as the system being destroyed, thereby ensuring continuous and normal operation of the instrument.

[0022] 5. The present invention distributes the cooling capacity of the refrigerant to each sample unit through a plurality of flexible cold chains with high thermal conductivity, thereby ensuring the uniformity of the temperature of the sample units of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The accompanying drawings constituting a part of the present invention are used to provide a further understanding of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the accompanying drawings:

[0024] Figure 1 This is a schematic diagram of a distributed flexible cold chain cryogenic system in the permanent shadow area of ​​the moon according to the present invention;

[0025] Figure 2 This is a schematic diagram of the interior of the vacuum cover of the present invention;

[0026] Figure 3 This is a schematic structural diagram of the thin-walled thermal bridge connector of the present invention;

[0027] Figure 4It is a schematic diagram of a composite variable density multi-layer thermal insulation component;

[0028] Figure 5 It is a schematic diagram of the connection between the flexible cold chain, the refrigerator and the sample unit;

[0029] Figure 6 Schematic diagram of the interior of the sample unit.

[0030] 1-refrigerator, 2-cold trap, 3-liquid nitrogen storage tank, 4-stop valve, 5-liquid nitrogen pump, 6-throttle valve, 7-vacuum cover, 8-low temperature vacuum environment simulator, 9-insulation support, 10-sample table, 11-composite variable density multi-layer insulation component, 12-variable density layer, 13-polyurethane foam unit, 14-outer thin-walled tube support, 15-inner thin-walled tube support, 16-room temperature connector, 17-cold storage unit, 18-temperature control unit, 19-flexible cold chain, 20-sample unit, 21-connection base, 22-heater, 23-insulation layer, 24-high specific heat storage material, 25-radiation shield, 26-thermal switch. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely explain the technical solutions in the embodiments of the present invention. It should be noted that the embodiments of the present invention and the features in the embodiments can be combined with each other without conflict, and the described embodiments are only part of the embodiments of the present invention, not all of the embodiments.

[0032] See also Figure 1-6 To illustrate the present embodiment, a distributed flexible cold chain low-temperature system for the permanent shadow area of ​​the moon includes a refrigerator 1, a cold trap 2, a liquid nitrogen storage tank 3, a vacuum cover 7, a low-temperature vacuum environment simulator 8, a sample table 10, a flexible cold chain 19 and a sample unit 20. The low-temperature vacuum environment simulator 8 is installed in the vacuum cover 7, and the output end of the liquid nitrogen storage tank 3 is connected to the low-temperature vacuum environment simulator 8. The sample table 10 is installed at the bottom of the low-temperature vacuum environment simulator 8. A plurality of sample units 20 are arranged on the sample table 10. A cold trap 2 is installed above the vacuum cover 7. The output end of the cold trap 2 passes through the vacuum cover 7 and is located in the low-temperature vacuum environment simulator 8. The cold trap 2 and the plurality of sample units 20 are connected to the refrigerator 1 through the flexible cold chain 19.

[0033] First, the deep low temperature environment of the permanent shadow area of ​​the moon is simulated in the low temperature vacuum environment simulator 8, and on this basis, the temperature gradient of the sample unit is created and regulated to realize the study of the adsorption and desorption effects of water ice on the lunar soil.

[0034] The low temperature environment control technology involves the guarantee of refrigeration and temperature stability during sample preparation, transportation and testing. At the same time, the temperature in the lunar polar region PSR is extremely low, which can be as low as 4.2-30K, and is distributed along the sample profile gradient. Therefore, the use of refrigerator 1 instead of the traditional liquid nitrogen cooling method as the low temperature cold source for permanent shadow area environment simulation can reduce the operating cost of the system. If the traditional liquid nitrogen cooling method is used, the low temperature vacuum environment simulator 8 is cooled from the liquid nitrogen temperature of 77K to the temperature of the lunar permanent shadow area of ​​30K, which requires 90 liters of liquid nitrogen. The use of refrigerator 1 to cool from room temperature to 30K consumes about 60kW·h of electricity. In addition, the system uses adiabatic technology and cold transfer method to smoothly cool the low temperature vacuum environment simulator 8 to the set temperature and meet the temperature uniformity requirements in the low temperature vacuum environment simulator 8. The sample in the sample unit 20 is captured by the cold trap 2.

[0035] The system simulates the use of a distributed flexible cold chain 19 to conduct cold energy, which can ensure that the samples in each sample unit 20 are in the lunar PSR30K deep low temperature environment, so that each sample is at a temperature similar to that of the permanent shadow area environment, and can ensure that the obtained sample characteristic indicators are closer to the theoretical predicted values ​​of water ice on the real lunar soil.

[0036] The pipeline between the liquid nitrogen storage tank 3 and the low-temperature vacuum environment simulator 8 is provided with a stop valve 4, a liquid nitrogen pump 5 and a throttle valve 6 in sequence along the liquid nitrogen delivery direction. A liquid nitrogen storage tank 3 is provided, and the low-temperature vacuum environment simulator 8 is cooled by a liquid nitrogen heat sink. The liquid nitrogen heat sink liquid is obtained by injecting or circulating liquid nitrogen into a system that needs to be cooled, and the low temperature of the liquid nitrogen is used to absorb heat, thereby achieving the purpose of cooling. It can work simultaneously with the refrigerator 1 to improve the efficiency of lowering the temperature.

[0037] Distributed cooling technology is used to meet the system's requirement for temperature uniformity in the sample unit 20 in the low-temperature vacuum environment simulator 8, and further the coldness of the refrigerator 1 is distributedly transferred to different cooling positions of the low-temperature vacuum environment simulator 8 through multiple high-thermal conductivity flexible cold chains 19.

[0038] A heat-insulating support 9 is installed below the sample stage 10 to reduce heat leakage from a high-temperature environment to the low-temperature sample stage 10 .

[0039] A composite variable-density multi-layer insulation component 11 is installed on the outside of the low-temperature vacuum environment simulator 8 .

[0040] The composite variable density multi-layer insulation component 11 includes a variable density layer 12 and a polyurethane foam unit 13. The polyurethane foam unit 13 is installed on the outer wall of the low-temperature vacuum environment simulator 8. The variable density layer 12 is installed on the outer side of the polyurethane foam unit 13. The high-vacuum composite variable density multi-layer insulation component 11 is used to reduce the heat leakage and thermal interference of the room temperature environment to the low-temperature vacuum environment simulator 8. The low-temperature vacuum environment simulator 8 adopts a high-vacuum double-layer structure. High vacuum insulation is used between the outer vacuum cover 7 and the inner outer wall of the low-temperature vacuum environment simulator 8 to reduce the convective heat exchange of the gas. The outer wall of the low-temperature vacuum environment simulator 8 is provided with an efficient variable density layer 12, and the variable density layer 12 is a composite variable density multi-layer material. The composite variable density multi-layer material is a composite material with different density levels and structures, and its density varies in space or depth direction. This material is usually composed of multiple layers of materials, each layer has a different density or density distribution, which can play a good insulating role. At the same time, high-efficiency insulating materials such as polyurethane foam that are insensitive to vacuum will be arranged between the low-temperature wall and the variable density layer 12 to provide efficient insulation in the event of emergencies such as system damage, thereby ensuring the continuous and normal operation of the instrument.

[0041] The inner wall surface of the low-temperature vacuum environment simulator 8 is coated with high-emissivity paint. Spraying high-emissivity paint on the inner wall surface of the low-temperature vacuum environment simulator 8 can effectively minimize and homogenize the radiation mean value in each lunar soil adsorption area under weak irradiation. In addition, it will be further assisted by relevant spatial structure optimization design and periodic rotation and exchange of control group samples and other strategies to further ensure uniform irradiation.

[0042] The vacuum cover 7 is connected to the low-temperature vacuum environment simulator 8 via a thin-walled thermal bridge connector, which reduces solid heat transfer by reducing the heat transfer area and extending the heat conduction path.

[0043] The thin-walled thermal bridge connector includes an outer thin-walled tube support 14, an inner thin-walled tube support 15 and a room temperature connector 16. The outer thin-walled tube support 14 is installed on the outside of the vacuum cover 7, the inner thin-walled tube support 15 is installed on the outside of the low-temperature vacuum environment simulator 8, the inner thin-walled tube support 15 is installed inside the outer thin-walled tube support 14, and a room temperature connector 16 is installed between the inner thin-walled tube support 15 and the outer thin-walled tube support 14.

[0044] The head of the refrigerator 1 is connected to the cold storage unit 17, one end of each flexible cold chain 19 connected to the sample unit 20 is connected to the cold storage unit 17, a temperature control unit 18 and a heat switch 26 are arranged between each flexible cold chain 19 and the sample unit 20, the sample unit 20 is connected to the flexible cold chain 19 through a connecting base 21, an insulating layer 23 is arranged on the outside of the sample unit 20, a high specific heat cold storage material 24 is arranged on the inside of the insulating layer 23, and both ends of the high specific heat cold storage material 24 are installed with a heating Heater 22, in order to increase the cooling rate of liquid nitrogen, for this system, regardless of whether the sample needs to be cooled, the refrigerator 1 will keep running. At this time, a cold storage unit 17 is introduced to continuously store the cold capacity of the refrigerator 1. When the sample needs to be cooled, the thermal switch 26 between the sample unit 20 and the flexible cold chain 19 is closed, so as to quickly cool the sample and achieve a large cold capacity output in a short time by the small cold capacity refrigerator 1. When the sample needs to be heated up, the thermal switch is disconnected and the heater 22 is started to realize rapid heating of the sample by electric heating.

[0045] Since the lengths and other dimensions of different flexible cold chains 19 are not completely consistent, an electric heating compensation method is added to the end of each flexible cold chain to achieve consistent control of the temperature at the end of the cold chain.

[0046] High specific heat storage materials 24 are used to store large amounts of heat and release it when needed. These materials have less temperature rise when absorbing heat and less temperature drop when releasing heat, so they can effectively maintain a relatively stable temperature during the heat storage and release process.

[0047] A radiation shield 25 is provided between the vacuum cover 7 and the low-temperature vacuum environment simulator 8. The radiation shield 25 can reduce radiation heat transfer.

[0048] The embodiments of the present invention disclosed above are only used to help illustrate the present invention. The embodiments do not describe all the details in detail, nor do they limit the invention to the specific implementation methods described. According to the content of this specification, many modifications and changes can be made. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well.

Claims

1. A distributed flexible cold chain low temperature system in the permanent shadow area of ​​the moon, characterized by: The invention comprises a refrigerator (1), a cold trap (2), a liquid nitrogen storage tank (3), a vacuum cover (7), a low-temperature vacuum environment simulator (8), a sample stage (10), a flexible cold chain (19) and a sample unit (20), wherein the low-temperature vacuum environment simulator (8) is installed in the vacuum cover (7), the output end of the liquid nitrogen storage tank (3) is connected to the low-temperature vacuum environment simulator (8), the sample stage (10) is installed at the bottom of the low-temperature vacuum environment simulator (8), a plurality of sample units (20) are arranged on the sample stage (10), a cold trap (2) is installed above the vacuum cover (7), the output end of the cold trap (2) passes through the vacuum cover (7) and is located in the low-temperature vacuum environment simulator (8), and the cold trap (2) and the plurality of sample units (20) are connected to the refrigerator (1) through the flexible cold chain (19).

2. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 1, characterized in that: A stop valve (4), a liquid nitrogen pump (5) and a throttle valve (6) are provided in sequence on the pipeline between the liquid nitrogen storage tank (3) and the low-temperature vacuum environment simulator (8) along the liquid nitrogen delivery direction.

3. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 1, characterized in that: A heat-insulating support (9) is installed below the sample stage (10).

4. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 1, characterized in that: A composite variable-density multi-layer thermal insulation component (11) is installed outside the low-temperature vacuum environment simulator (8).

5. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 4, characterized in that: The composite variable-density multi-layer thermal insulation component (11) comprises a variable-density layer (12) and a polyurethane foam unit (13); the polyurethane foam unit (13) is installed on the outer wall surface of the low-temperature vacuum environment simulator (8); and the variable-density layer (12) is installed outside the polyurethane foam unit (13).

6. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 4, characterized in that: The inner wall surface of the low-temperature vacuum environment simulator (8) is coated with a high-emissivity coating.

7. The distributed flexible cold chain cryogenic system for the permanent shadow area of ​​the moon according to claim 1, characterized in that: The vacuum cover (7) and the low-temperature vacuum environment simulator (8) are connected via a thin-walled thermal bridge connector.

8. A distributed flexible cold chain low temperature system for the permanent shadow area of ​​the moon according to claim 7, characterized in that: The thin-walled thermal bridge connector comprises an outer thin-walled tube support (14), an inner thin-walled tube support (15) and a room temperature connector (16); the outer thin-walled tube support (14) is installed on the outside of a vacuum cover (7); the inner thin-walled tube support (15) is installed on the outside of a low-temperature vacuum environment simulator (8); the inner thin-walled tube support (15) is installed inside the outer thin-walled tube support (14); and a room temperature connector (16) is installed between the inner thin-walled tube support (15) and the outer thin-walled tube support (14).

9. The distributed flexible cold chain cryogenic system for the permanent shadow area of ​​the moon according to claim 1, characterized in that: The head of the refrigerator (1) is connected to a cold storage unit (17), one end of each flexible cold chain (19) connected to a sample unit (20) is connected to the cold storage unit (17), a temperature control unit (18) and a heat switch (26) are provided between each flexible cold chain (19) and the sample unit (20), the sample unit (20) is connected to the flexible cold chain (19) via a connecting base (21), an insulating layer (23) is provided on the outside of the sample unit (20), a high specific heat cold storage material (24) is provided on the inside of the insulating layer (23), and heaters (22) are installed at both ends of the high specific heat cold storage material (24).

10. The distributed flexible cold chain low temperature system in the permanent shadow area of ​​the moon according to claim 1, characterized in that: A radiation protection screen (25) is provided between the vacuum cover (7) and the low-temperature vacuum environment simulator (8).

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