A lunar permanent shadow area distributed flexible cold chain low temperature system

Abstract

The application provides a lunar permanent shadow area distributed flexible cold chain low-temperature system and belongs to the technical field of lunar permanent shadow area low-temperature environment simulation. The application solves the problem that the physical indexes such as thermal-electric-optical-desorption characteristics of the lunar soil water ice simulation object in the prior art are greatly different from the theoretical predicted values of the real lunar soil water ice. The application comprises a refrigerator, 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. The sample table is installed at the bottom of the low-temperature vacuum environment simulator. The sample table is provided with a plurality of sample units. The output end of the cold trap penetrates through the vacuum cover and is located in the low-temperature vacuum environment simulator. The cold trap and the plurality of sample units are connected with the refrigerator through the flexible cold chain. The application is mainly used for simulating the ice soil material mining under the lunar permanent shadow area environment.

Description

Technical Field

[0001] This invention belongs to the field of low-temperature environment simulation technology in the permanently shadowed region of the moon, and in particular relates to a distributed flexible cold chain low-temperature system in the permanently shadowed region of the moon. Background Technology

[0002] Since the beginning of the 21st century, humankind has demonstrated through long-range remote sensing that naturally occurring ice water exists in the permanently shadowed regions at the lunar poles, manifesting as ice-reservoir aggregates within lunar regolith profiles. Why does this naturally occurring ice water exist under the extremely high vacuum conditions of the Moon? The scientific mechanism suggests three key factors: first, the extreme low temperatures and lack of sunlight in the permanently shadowed regions provide the conditions for cold trap sublimation of water; second, there must be a global influx of rarefied water molecules; and third, physical interactions such as cold trap capture, adsorption deposition, and cold-end migration occur between water molecules and lunar regolith particles.

[0003] Planetary science and remote sensing evidence indicate that the lowest temperatures in the permanently shadowed regions at the lunar poles can reach around 10-30K, with lunar atmospheric pressure on the order of 10-10 Pa. Such extreme low temperatures and vacuum conditions far exceed the research limits of Earth's permafrost and conventional water materials. Under the coupled low temperature and vacuum conditions in the permanently shadowed regions of the Moon, complex physical processes such as cold trap capture, adsorption deposition, and cold end migration may occur between the sparse water molecules originating from global free diffusion and lunar regolith particles, thereby forming stable ice-regolith aggregates. Due to the limitations of deep space exploration capabilities, humans have not yet obtained in-situ sampling and detailed investigation evidence of lunar regolith water-ice materials. The formation and evolution mechanisms of ice-regolith materials in the permanently shadowed regions of the Moon, as well as the influence factors of environmental and material factors on the comprehensive physical properties of ice-regolith aggregates, are still unclear.

[0004] To address the critical needs of scientific investigation, resource extraction, and utilization of ice-soil materials within the permanently shadowed regions of the moon, fundamental issues such as lunar soil-water ice material simulation and comprehensive physical property testing and characterization of lunar soil-water ice urgently require solutions. Existing technologies employ three methods—normal-pressure water freezing, low-temperature ice-soil mixing, and normal-pressure vapor condensation—which can basically meet the requirements for envelope simulation and engineering verification of the stringent mechanical properties of lunar soil-water ice. However, the simulation preparation methods and process conditions have a low degree of consistency with the scientific mechanisms of the actual formation and evolution of lunar soil-water ice, resulting in significant discrepancies between the thermal, electrical, optical, and desorption properties of the simulated lunar soil-water ice and the theoretically 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 permanently shadowed region of the moon, in order to solve the problem that the existing methods and processes for preparing simulated ice-soil materials in the permanently shadowed region of the moon have a low degree of consistency with the scientific mechanism of the actual formation and evolution of lunar soil water ice, resulting in a large gap between the thermal, electrical, optical and desorption properties of the simulated lunar soil water ice and the theoretical predictions of the actual lunar soil water ice.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] A distributed flexible cold chain cryogenic system for a permanently shadowed lunar region includes a refrigerator, a cold trap, a liquid nitrogen storage tank, a vacuum chamber, a cryogenic vacuum environment simulator, a sample stage, a flexible cold chain, and sample units. The cryogenic vacuum environment simulator is installed inside the vacuum chamber. 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 and has multiple sample units. A cold trap is installed above the vacuum chamber, and the output end of the cold trap passes through the vacuum chamber and is located inside the cryogenic vacuum environment simulator. The cold trap and multiple sample units are all connected to the refrigerator via a flexible cold chain.

[0008] Furthermore, the pipeline between the liquid nitrogen storage tank and the cryogenic vacuum environment simulator is equipped with a shut-off valve, a liquid nitrogen pump, and a throttle valve in sequence along the liquid nitrogen delivery direction.

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

[0010] Furthermore, the low-temperature vacuum environment simulator is equipped with a composite variable density multilayer insulation component on its outer side.

[0011] Furthermore, the composite variable density multilayer insulation component includes a variable density layer and a polyurethane foam unit. The polyurethane foam unit is installed on the outer wall of the low-temperature vacuum environment simulator, and the variable density layer is installed on the outside of 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 hood 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 chamber, 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 refrigeration unit is connected to the cold storage unit, and one end of each flexible cold chain connected to the sample unit is connected to the cold storage unit. Each flexible cold chain and the sample unit is equipped with a temperature control unit and a thermal switch. The sample unit is connected to the flexible cold chain through a connecting base. The outer side of the sample unit is provided with a heat insulation layer, and the inner side of the heat insulation layer is provided with a high specific heat cold storage material. Heaters are installed at both ends of the high specific heat cold storage material.

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

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] 1. This invention uses a mechanical refrigeration unit instead of the traditional liquid nitrogen cooling method as the low-temperature cold source for the permanent shadow area environment, which can reduce the operating cost of the instrument.

[0019] 2. The present invention combines thermal insulation technology and cold energy transfer method to successfully cool the cavity to the set temperature, thereby meeting the requirements of cavity temperature uniformity.

[0020] 3. The present invention uses composite variable density multilayer insulation components, which reduces the heat leakage and thermal interference of room temperature environment on low temperature vacuum environment simulator.

[0021] 4. The present invention incorporates a high-efficiency heat insulation material, such as polyurethane foam, which is insensitive to vacuum levels, between the vacuum chamber and the low-temperature vacuum environment simulator. This material provides efficient heat insulation in the event of sudden events such as system failure, ensuring the continuous and normal operation of the instrument.

[0022] 5. The present invention distributes the cooling capacity of the refrigerant to each sample unit through multiple flexible cold chains with high thermal conductivity, thereby ensuring the uniformity of the temperature of the sample units by the system. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0024] Figure 1 This is a schematic diagram of a distributed flexible cold chain cryogenic system for a permanently shadowed region of the moon, as described in this invention.

[0025] Figure 2 This is a schematic diagram of the interior of the vacuum chamber described in this invention;

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

[0027] Figure 4This is a schematic diagram of a composite variable density multilayer thermal insulation component;

[0028] Figure 5 This is a schematic diagram showing the connection between the flexible cold chain, the refrigeration unit, and the sample unit.

[0029] Figure 6 This is a 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 hood, 8-Low temperature vacuum environment simulator, 9-Insulation support, 10-Sample stage, 11-Composite variable density multilayer 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-Connecting base, 22-Heater, 23-Insulation layer, 24-High specific heat cold storage material, 25-Radiation shield, 26-Thermal switch. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of the present invention can be combined with each other, and the described embodiments are only some embodiments of the present invention, not all embodiments.

[0032] See Figure 1-6 This embodiment describes a distributed flexible cold chain cryogenic system for a permanently shadowed lunar region, comprising a refrigerator 1, a cold trap 2, a liquid nitrogen storage tank 3, a vacuum chamber 7, a cryogenic vacuum environment simulator 8, a sample stage 10, a flexible cold chain 19, and sample units 20. The cryogenic vacuum environment simulator 8 is installed inside the vacuum chamber 7. The output end of the liquid nitrogen storage tank 3 is connected to the cryogenic vacuum environment simulator 8. The sample stage 10 is installed at the bottom of the cryogenic vacuum environment simulator 8, and multiple sample units 20 are provided on the sample stage 10. The cold trap 2 is installed above the vacuum chamber 7, and the output end of the cold trap 2 penetrates the vacuum chamber 7 and is located inside the cryogenic vacuum environment simulator 8. The cold trap 2 and the multiple sample units 20 are all connected to the refrigerator 1 through the flexible cold chain 19.

[0033] First, the deep low-temperature environment of the permanently shadowed region of the moon was simulated in the low-temperature vacuum environment simulator 8. Based on this, the temperature gradient of the sample unit was created and controlled to study the adsorption and desorption effects of water ice on lunar soil.

[0034] Cryogenic environment control technology involves ensuring refrigeration and temperature stability during sample preparation, transportation, and testing. Meanwhile, the temperature within the lunar polar region PSR is extremely low, ranging from 4.2 to 30 K, and exhibits a gradient distribution along the sample profile. Therefore, using a refrigerator 1 instead of the traditional liquid nitrogen cooling method as the cryogenic cold source for simulating the permanent shadow region reduces the system's operating costs. If the traditional liquid nitrogen cooling method is used, cooling the cryogenic vacuum environment simulator 8 from a liquid nitrogen temperature of 77 K to a lunar permanent shadow region temperature of 30 K would require 90 liters of liquid nitrogen. Using the refrigerator 1 to lower the temperature from room temperature to 30 K would consume approximately 60 kW·h of electricity. Furthermore, the system employs insulation technology and cold energy transfer methods to successfully cool the cryogenic vacuum environment simulator 8 to the set temperature and meet the temperature uniformity requirements within the simulator 8. Samples within sample unit 20 are captured via a cold trap 2.

[0035] The system simulates the conduction of cold energy using a distributed flexible cold chain 19, 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 permanently shadowed area. This ensures that the obtained sample characteristic indicators are closer to the theoretical predictions of water ice on the real lunar soil.

[0036] The pipeline between the liquid nitrogen storage tank 3 and the cryogenic vacuum environment simulator 8 is sequentially equipped with a shut-off valve 4, a liquid nitrogen pump 5, and a throttling valve 6 along the liquid nitrogen delivery direction. The liquid nitrogen storage tank 3 is provided, and the cryogenic vacuum environment simulator 8 is cooled by liquid nitrogen heat sink. The liquid nitrogen heat sink is obtained by injecting or circulating liquid nitrogen into the system that needs to be cooled, and the low temperature of 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 temperature reduction.

[0037] Distributed cooling technology is adopted to meet the system's requirement for temperature uniformity within the sample unit 20 of the low-temperature vacuum environment simulator 8. Furthermore, the cooling capacity of the refrigerator 1 is distributed to different cooling locations of the low-temperature vacuum environment simulator 8 through multiple flexible cold chains 19 with high thermal conductivity.

[0038] A thermal insulation support 9 is installed below the sample stage 10 to reduce heat leakage between the high-temperature environment and the low-temperature sample stage 10.

[0039] The low-temperature vacuum environment simulator 8 is equipped with a composite variable density multilayer insulation component 11 on its outside.

[0040] The composite variable density multilayer 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, and the variable density layer 12 is installed on the outside of the polyurethane foam unit 13. The high-vacuum composite variable density multilayer 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. The outer vacuum cover 7 and the inner low-temperature vacuum environment simulator 8 outer wall are insulated with high vacuum to reduce the convective heat transfer of the gas. The outer wall of the low-temperature vacuum environment simulator 8 is provided with a high-efficiency variable density layer 12, and the variable density layer 12 is a composite variable density multilayer material. The composite variable density multilayer material is a composite material with different density levels and structures, and its density varies in the spatial or depth direction. This material is typically composed of multiple layers, each with a different density or density distribution, which provides excellent thermal insulation. At the same time, high-efficiency thermal insulation materials such as polyurethane foam, which are not sensitive to vacuum, are placed between the low-temperature wall and the variable density layer 12 to provide efficient thermal insulation in case of system failure or other emergencies, ensuring the continuous normal operation of the instrument.

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

[0042] The vacuum chamber 7 is connected to the low-temperature vacuum environment simulator 8 by 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 chamber 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 compressor 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. Each flexible cold chain 19 is provided with a temperature control unit 18 and a thermal switch 26 between it and the sample unit 20. The sample unit 20 is connected to the flexible cold chain 19 via a connecting base 21. The outer side of the sample unit 20 is provided with a heat insulation layer 23, and the inner side of the heat insulation layer 23 is provided with a high specific heat storage material 24. Both ends of the high specific heat storage material 24 are equipped with heating elements. Heater 22: In order to improve the cooling rate of liquid nitrogen, the refrigerator 1 will continue to run regardless of whether the sample needs to be cooled. At this time, a cold storage unit 17 is introduced to continuously store the cold energy 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 to quickly cool the sample, thereby realizing a large cold energy output of the small cold energy refrigerator 1 in a short time. When the sample needs to be heated, the thermal switch is turned off and the heater 22 is started to achieve rapid heating of the sample through electric heating.

[0045] Since the lengths and other dimensions of different flexible cold chains 19 are not completely consistent, the temperature at the end of the cold chain is controlled consistently by adding electric heating compensation at the end of each flexible cold chain.

[0046] High specific heat storage material 24 is used to store a large amount of heat and release it when needed. These materials have a small temperature rise when absorbing heat and a small temperature drop when releasing heat, thus effectively maintaining a relatively stable temperature during heat storage and release.

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

[0048] The embodiments of the present invention disclosed above are merely illustrative of the invention. These embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention.

Claims

1. A distributed flexible cryogenic cold chain system for permanently shadowed regions of the moon, characterized in that: The system includes a refrigerator (1), a cold trap (2), a liquid nitrogen storage tank (3), a vacuum hood (7), a low-temperature vacuum environment simulator (8), a sample stage (10), a flexible cold chain (19), and sample units (20). The low-temperature vacuum environment simulator (8) is installed inside the vacuum hood (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). Multiple sample units (20) are provided on the sample stage (10). The cold trap (2) is installed above the vacuum hood (7). The output end passes through the vacuum hood (7) and is located inside the low-temperature vacuum environment simulator (8). The cold trap (2) and multiple sample units (20) are connected to the refrigerator (1) through a flexible cold chain (19). A composite variable density multilayer insulation component (11) is installed on the outside of the low-temperature vacuum environment simulator (8). The composite variable density multilayer insulation component (11) includes a variable density layer (12) and a polyurethane foam unit (13). A polyurethane foam unit (13) is installed on the outer wall of the low-temperature vacuum environment simulator (8). A variable density layer (12) is installed on the outside of the polyurethane foam unit (13).

2. The distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: The pipeline between the liquid nitrogen storage tank (3) and the low-temperature vacuum environment simulator (8) is provided with a shut-off valve (4), a liquid nitrogen pump (5) and a throttle valve (6) in sequence along the liquid nitrogen delivery direction.

3. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: A thermal support (9) is installed below the sample stage (10).

4. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: The inner wall of the low-temperature vacuum environment simulator (8) is coated with a high emissivity coating.

5. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: The vacuum hood (7) and the low-temperature vacuum environment simulator (8) are connected by a thin-walled thermal bridge connector.

6. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 5, characterized in that: 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 chamber (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).

7. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: The head of the refrigeration unit (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). Each flexible cold chain (19) and the sample unit (20) are provided with a temperature control unit (18) and a thermal switch (26). The sample unit (20) is connected to the flexible cold chain (19) through a connecting base (21). The sample unit (20) is provided with a heat insulation layer (23) on the outside. The heat insulation layer (23) is provided with a high specific heat storage material (24) on the inside. Both ends of the high specific heat storage material (24) are equipped with heaters (22).

8. A distributed flexible cold chain cryogenic system for permanently shadowed lunar regions according to claim 1, characterized in that: A radiation shield (25) is provided between the vacuum hood (7) and the low-temperature vacuum environment simulator (8).

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