Enrichment device and control method thereof

Abstract

The present invention belongs to the technical field of analysis and detection, and specifically relates to an enrichment device and a control method thereof, the enrichment device comprises a vacuum chamber and a refrigerator, an enrichment tube, an enrichment driver and a heater arranged therein, the enrichment driver is used to drive the enrichment tube to approach or move away from the cold end of the refrigerator, the heater is used to heat the enrichment tube, the cold end of the refrigerator has an enrichment fitting groove, the structure of the enrichment fitting groove matches the structure of the enrichment tube, so that the enrichment tube and the enrichment fitting groove are fitted with each other; the cold end of the refrigerator is provided with a clamping piece that is rotatably matched with the notch of the enrichment fitting groove, and the clamping piece is used to adjust the position of the enrichment tube so that it is fitted with the surface between the enrichment fitting groove. The present invention utilizes the clamping piece to achieve close surface fitting between the enrichment tube and the enrichment fitting groove, effectively improving the enrichment effect.

Description

Technical Field

[0001] The invention belongs to the technical field of analysis and detection, and particularly relates to an enrichment device and a control method thereof. Background Art

[0002] In the monitoring of organic matter, enrichment devices are usually used to improve the detection accuracy of gas chromatographs (hydrogen flame detectors) GC-FID, gas chromatography-mass spectrometers GC-MS and other equipment. The enrichment device mainly includes a vacuum chamber, a refrigerator, an enrichment tube, a motion mechanism and a heater. In practical applications, the conditions that affect the life and performance of the enrichment device mainly include the following three:

[0003] (1) Frosting at the cold end of the refrigerator in a low-pressure environment is related to temperature, vacuum pressure, and the enrichment temperature of different organic matter is different. Rough control of vacuum and refrigeration temperature will lead to inconsistent frosting, affecting the travel speed and life of the motion mechanism, and also affecting the refrigeration efficiency of the enrichment tube;

[0004] (2) The bonding area between the enrichment tube and the cold end of the refrigerator directly affects the effectiveness of organic matter enrichment and the efficiency of analysis. The enrichment tube is bonded to the cold end of the refrigerator by a motion mechanism. However, due to the precision of the motion mechanism and the rebound effect of the bonding structure, it is difficult to achieve a tight surface fit. If the enrichment tube and the cold end of the refrigerator are in contact for too long, the life of the motion mechanism will be affected.

[0005] (3) There is a power outage in outdoor online monitoring. Since the refrigerator takes at least 2 hours to cool down naturally to normal temperature, when the vacuum chamber is not continuously operated by the vacuum pump, air will infiltrate and cause condensation water to accumulate in the chamber, thereby causing damage to electrical and moving parts.

[0006] Therefore, there is an urgent need in this field to design an enrichment device with fine control to achieve better enrichment performance while achieving high stability and long life operation. Summary of the invention

[0007] Based on the above-mentioned shortcomings and deficiencies in the prior art, one of the objects of the present invention is to at least solve one or more of the above-mentioned problems in the prior art. In other words, one of the objects of the present invention is to provide an enrichment device and a control method thereof that meet one or more of the above-mentioned needs.

[0008] In order to achieve the above-mentioned object of the invention, the present invention adopts the following technical solutions:

[0009] An enrichment device comprises a vacuum chamber and a refrigerator, an enrichment tube, an enrichment driving member and a heater arranged therein, wherein the enrichment driving member is used to drive the enrichment tube to approach or move away from the cold end of the refrigerator, and the heater is used to heat the enrichment tube. The cold end of the refrigerator has an enrichment bonding groove, and the structure of the enrichment bonding groove matches the structure of the enrichment tube, so that the enrichment tube and the enrichment bonding groove are bonded to each other.

[0010] The cold end of the refrigerator is provided with a clamping piece which is rotatably matched with the notch of the enrichment bonding groove, and the clamping piece is used to adjust the position of the enrichment tube so that it is bonded with the surface between the enrichment bonding groove.

[0011] As a preferred solution, both ends of the enrichment tube are provided with limit blocks, and the positioning pieces correspond to the limit blocks one by one;

[0012] When the positioning member rotates to the first target position, the enrichment tube is prevented from entering the enrichment bonding tank or away from the enrichment bonding tank;

[0013] When the clamping member rotates to the second target position, the clamping member abuts against the limiting block, so that the enrichment tube and the enrichment bonding groove are bonded to each other.

[0014] As a preferred solution, the rotation of the locking member is driven by a locking driving member;

[0015] The enrichment device also includes a controller, which is connected to the refrigerator, the enrichment drive, the heater, and the positioning drive by signals.

[0016] As a preferred solution, the enrichment tube is provided with a temperature sensor, and the temperature sensor is connected to the controller signal;

[0017] When the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate to the second target position;

[0018] When the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate to the first target position;

[0019] The first target temperature is higher than the second target temperature, and the second target temperature is within a preset temperature range of the cooling temperature of the refrigerator.

[0020] As a preferred solution, the enrichment tube is an arc-shaped structure, a V-shaped structure, or a spiral structure.

[0021] As a preferred solution, an elastic connecting member is provided between the enrichment tube and the enrichment driving member.

[0022] As a preferred solution, the vacuum chamber is provided with an anti-condensation and frost protection gas circuit;

[0023] The anti-condensation and frost protection gas circuit includes an air compressor, a filter, a normally open solenoid valve, a one-way valve and an air outlet end head which are arranged in sequence along the flow direction of the gas circuit. The filter is used to remove water, oil and particulate matter, and the air outlet of the air outlet end head faces the cold end of the refrigerator.

[0024] As a preferred solution, the vacuum chamber is connected to a vacuum pump.

[0025] The present invention also provides a control method for the enrichment device as described in any of the above schemes, comprising the following steps:

[0026] S1. According to N The boiling point of the substance being measured is used to calculate the refrigeration temperature of the enrichment device. T 1. Desorption temperature T 2. Vacuum degree of vacuum chamber P ;

[0027] Among them, the cooling temperature T 1 is:

[0028] ;

[0029] Desorption temperature T 2 is:

[0030] ;

[0031] T i For the i The boiling point of the substance being tested, i∈[1, N ], N is an integer greater than 1; is a first preset temperature difference;

[0032] Vacuum degree of vacuum chamber P for:

[0033] ;

[0034] in, A , B , C is the fitting coefficient, T 0 is the ambient temperature;

[0035] S2, wait for the vacuum chamber to reach the vacuum degree P , start the refrigerator;

[0036] S3, the enrichment driving member drives the enrichment tube to fit the enrichment fitting groove, and when the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate from the first target position to the second target position;

[0037] S4, when the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate from the second target position to the first target position, the enrichment driving member drives the enrichment tube to separate from the enrichment bonding tank and starts the heater, and when the temperature collected by the temperature sensor reaches the third target temperature, all the measured substances are desorbed;

[0038] The second target temperature , the third target temperature ; is the second preset temperature difference, ;

[0039] S5, repeating the above steps S3 to S4 to achieve enrichment and desorption cycles.

[0040] As a preferred solution, step S1 further includes: according to the refrigeration temperature T 1. Desorption temperature T 2 Calculate the heating rate of the heater K :

[0041] ;

[0042] in, L To enrich the driving stroke of the driving parts, v is the driving speed of the enrichment driving member.

[0043] Compared with the prior art, the present invention has the following beneficial effects:

[0044] (1) The present invention uses a clamping piece to achieve close surface bonding between the enrichment tube and the enrichment bonding tank, effectively improving the enrichment effect;

[0045] (2) The anti-condensation and frost protection gas circuit designed by the present invention realizes self-protection in the case of power failure, which can not only prevent condensation and frost at the cold end of the refrigerator, but also prevent air infiltration from causing accumulation of condensed water in the vacuum chamber, resulting in damage to electrical and drive components;

[0046] (3) The present invention accurately controls the vacuum degree and refrigeration temperature according to the boiling point of the substance being measured, thereby preventing frost from forming on the cold end of the refrigerator, which would affect the travel speed and life of the driving parts, and effectively improve the refrigeration efficiency of the enrichment tube. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 is a schematic structural diagram of an enrichment device according to Example 1 of the present invention;

[0048] Figure 2 is a schematic diagram of the concave-convex positioning structure of the abutting surface between the locking member and the cold end of the refrigerator in Example 1 of the present invention;

[0049] Figure 3It is a schematic diagram of the motion change state of the enrichment device of Example 1 of the present invention. DETAILED DESCRIPTION

[0050] In order to more clearly illustrate the embodiments of the present invention, the specific implementation methods of the present invention will be described below with reference to the accompanying drawings. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings and other implementation methods can be obtained based on these accompanying drawings without creative work.

[0051] Embodiment 1:

[0052] like Figure 1 As shown, the enrichment device of this embodiment includes a vacuum chamber 1, a refrigerator 2, an enrichment tube 3, an enrichment drive 4, a heater, a vacuum pump 5 and an anti-condensation and frost protection gas circuit. The vacuum chamber 1 is connected to the vacuum pump 5 for evacuating the vacuum chamber 1; the cold end of the refrigerator 2, the enrichment tube 3, the enrichment drive 4 and the heater are installed in the vacuum chamber 1.

[0053] The enrichment drive 4 of this embodiment adopts a cylinder or a motor to drive the enrichment tube 3 to approach or move away from the cold end of the refrigerator 2 for enrichment or desorption; the heater is used to heat the enrichment tube 3, and instantaneous heating is achieved by inputting a large current into the enrichment tube 3 made of metal material to achieve desorption. The specific structure of the heater can refer to the prior art and will not be repeated here. Among them, the enrichment tube 3 is a C-shaped arc structure, and an elastic connector T is provided between the enrichment tube 3 and the enrichment drive 4, and the elastic connector T can be a spring. In addition, the enrichment tube 3 is provided with a temperature sensor for real-time acquisition of the temperature of the enrichment tube 3.

[0054] The cold end of the refrigerator 2 of this embodiment has an enrichment fitting groove 20, and the structure of the enrichment fitting groove 20 matches the structure of the enrichment tube 3, so that the enrichment tube 3 and the enrichment fitting groove 20 can be fitted with each other, which is conducive to improving the enrichment effect. In addition, the cold end of the refrigerator 2 is equipped with a clamping member 6, which is rotatably matched with the notch of the enrichment fitting groove 20, and the clamping member 6 is used to adjust the position of the enrichment tube 3 so that the enrichment tube 3 and the enrichment fitting groove 20 form a tight surface fit; such a design can ensure that when the enrichment drive member has insufficient driving stroke after long-term use, the clamping member can still be used to ensure a tight fit between the enrichment tube and the enrichment fitting groove.

[0055] Specifically, limit blocks 7 are respectively provided at both ends of the enrichment tube 3, and the clamping member 6 corresponds to the limit blocks 7 one by one. When the clamping member 6 rotates to the first target position, the enrichment fitting groove 20 is fully opened to prevent the enrichment tube 3 from entering the enrichment fitting groove 20 or moving away from the enrichment fitting groove 20; when the clamping member 6 rotates to the second target position, during the rotation process, if the enrichment tube and the enrichment fitting groove are not tightly fitted, the clamping member 6 can link the enrichment tube 3 to tightly fit to the enrichment fitting groove 20, and at this time, the clamping member 6 abuts against the limit blocks 7 to maintain a tight surface fit between the enrichment tube 3 and the enrichment fitting groove 20. Among them, the rotation of the clamping member 6 is driven by a clamping drive member, and the clamping drive member can adopt an existing conventional motor. The specific driving structure can refer to the prior art and will not be repeated here. In addition, if Figure 2 As shown, the abutting surface between the locking member 6 and the cold end of the refrigerator 2 is positioned by a concave-convex positioning structure, which includes a positioning hole 21 located at the cold end of the refrigerator 2 and a positioning protrusion 61 located at the locking member 6.

[0056] The enrichment device of this embodiment also includes a controller, which is connected to the refrigerator, the enrichment drive, the heater, the positioning drive, and the temperature sensor signal to realize intelligent control of the enrichment device. The main control logic is as follows:

[0057] When the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate to the second target position;

[0058] When the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate to the first target position;

[0059] Among them, the first target temperature is higher than the second target temperature, and the second target temperature is within a preset temperature range of the refrigeration temperature of the refrigerator; the first target temperature can be set to half of the refrigeration temperature, for example, to realize intelligent driving of the positioning drive component.

[0060] The anti-condensation and frost protection gas circuit of this embodiment includes an air compressor I, a filter II, a normally open solenoid valve III, a one-way valve IV and an air outlet terminal V arranged in sequence along the flow direction of the gas circuit. The filter II is used to remove water, oil and particulate matter, and the air outlet of the air outlet terminal V faces the cold end of the refrigerator. Since the online monitoring volatile organic compound analyzer often has abnormal power failures, after the power failure, the enrichment device realizes self-protection in the absence of power supply and vacuum pump operation to prevent air from infiltrating and causing condensed water accumulation in the vacuum chamber, resulting in damage to electrical and drive components. The specific principle is as follows:

[0061] (a) When the enrichment device is powered off, the normally open solenoid valve changes from the original closed state to the normally open state due to the power failure;

[0062] (b) Since the vacuum chamber is in a vacuum state, the air is dehydrated, deoiled and particulate matter removed by the air compressor and filter to form dry air, which then enters the vacuum chamber through the normally open solenoid valve and the one-way valve and directly blows the cold end of the refrigerator, filling the vacuum chamber until it is balanced with the atmospheric pressure; the one-way valve prevents gas backflow;

[0063] (c) Dry air causes the air pressure and temperature of the vacuum chamber to quickly reach the normal pressure and room temperature level, making it impossible for the cold end of the refrigerator to meet the environmental conditions of condensation and frost.

[0064] Therefore, in the power-off state, the vacuum chamber is effectively prevented from condensing and forming water inside the chamber due to the long natural cooling time of the refrigerator, which in turn causes damage to electrical components and moving parts, affecting the life and reliability of the enrichment device.

[0065] like Figure 3 As shown, the control method of the enrichment device of this embodiment includes the following steps:

[0066] (1) Based on N The boiling point of the substance being measured is used to calculate the refrigeration temperature of the enrichment device. T 1. Desorption temperature T 2. Vacuum degree of vacuum chamber P , Heater heating rate K ;

[0067] Specifically, the cooling temperature of this embodiment is T 1 is:

[0068] ;

[0069] The desorption temperature of this example T 2 is:

[0070] ;

[0071] T i For the i The boiling point of the substance being tested, i∈[1, N ], N is an integer greater than 1; is a first preset temperature difference, for example, set to 10°C;

[0072] The vacuum degree of the vacuum chamber of this embodiment is P for:

[0073] ;

[0074] in, A , B , C are the fitting coefficients, as an example, AThe value is 133.3. B The value is 24.01849. C The value is 6144.96; T 0 is the ambient temperature;

[0075] The heating rate of this embodiment K for:

[0076] ;

[0077] in, L To enrich the driving stroke of the driving parts, v is the driving speed of the enrichment driving member;

[0078] (2) Start the vacuum pump and wait until the vacuum chamber reaches a certain vacuum degree. P , start the refrigerator;

[0079] (3) The enrichment driving member drives the enrichment tube to fit the enrichment fitting groove. When the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate from the first target position to the second target position.

[0080] This embodiment uses the first target temperature as a trigger condition for driving the locking driving member, thereby realizing intelligent driving of the locking driving member;

[0081] (4) When the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate from the second target position to the first target position, and the enrichment driving member drives the enrichment tube to separate from the enrichment bonding tank and starts the heater. When the temperature collected by the temperature sensor reaches the third target temperature, all the measured substances are desorbed;

[0082] The second target temperature , the third target temperature ; is the second preset temperature difference, ;For example Set to 5℃; as an example, the duration preset time is set to 3-5s;

[0083] This embodiment uses the second target temperature and the preset time as another triggering condition for the positioning drive member and the triggering condition for the enrichment drive member to realize the intelligent driving of the positioning drive member and the enrichment drive member;

[0084] (5) Repeat the above steps (3) to (4) to achieve enrichment and desorption cycles.

[0085] When the enrichment device and control method of this embodiment are applied to the analysis of 116 ozone precursor volatile organic compounds, the refrigeration temperature of the refrigerator is set according to the boiling point of the organic compounds. T1 is -60~-55℃, desorption temperature T 2 is 130℃, then the vacuum degree in the vacuum chamber is P Set to 30-50Pa, heating rate K It is 120℃ / s.

[0086] The enrichment device of comparative example 1 is different from the enrichment device of embodiment 1 in that there is no design of a retaining piece, and the vacuum pump adopts a mechanical pump, which can only reach 10Pa due to the lack of vacuum degree adjustment capability; the other components are the same as those of embodiment 1.

[0087] For comparison, the refrigeration temperature is set to -60°C. The enrichment device of this embodiment adopts an adjustable speed vacuum pump, the vacuum degree is set to 50Pa, and the enrichment temperature difference is detected by the temperature sensor on the enrichment tube. The specific data are shown in Table 1 below.

[0088] Table 1 Enrichment temperature collected by the temperature sensor on the enrichment tube

[0089]

[0090] As can be seen from Table 1, the temperature difference of the enrichment device of Comparative Example 1 is as high as 14°C or more after 45 days of use. This is mainly caused by the frosting layer on the cold surface of the refrigerator and the inadequate bonding of the enrichment tube to the enrichment bonding groove. However, this embodiment effectively reduces frosting through vacuum and temperature control, and makes the enrichment tube and the enrichment bonding groove fit tightly through the clamping piece. After 60 days of use, the temperature difference is still controlled within 3.6°C, which can achieve the optimal enrichment efficiency and equipment stability. Therefore, this embodiment sets the vacuum degree target value according to the frosting at the cold end of the refrigerator, so that under the best energy efficiency, while ensuring the effective enrichment of organic matter, the frosting at the cold end is minimized.

[0091] In addition, the enrichment device and control method of this embodiment can also be used to analyze 47 kinds of fluorine-containing greenhouse gases, and the refrigeration temperature of the refrigerator can be set according to the boiling point of organic matter. T 1 is -180~-150℃, desorption temperature T 2 is 100°C, then the vacuum degree in the vacuum chamber is P Set to 0.01Pa, heating rate K is 100℃ / s.

[0092] Embodiment 2:

[0093] The enrichment device of this embodiment is different from that of embodiment 1 in that:

[0094] There is no elastic connection between the enrichment tube and the enrichment driving part, but a direct rigid connection is adopted;

[0095] When the clamping member drives the enrichment tube, the elastic deformation of the enrichment tube itself can also be used to achieve a close surface fit between the enrichment tube and the enrichment fitting groove;

[0096] For other structures and control methods, please refer to Example 1.

[0097] Embodiment 3:

[0098] The enrichment device of this embodiment is different from that of embodiment 1 in that:

[0099] The abutting surface between the positioning member and the cold end of the refrigerator adopts a concave-convex positioning structure to achieve positioning, and the concave-convex positioning structure includes a positioning hole protrusion located at the cold end of the refrigerator and a positioning hole located at the positioning member;

[0100] For other structures and control methods, please refer to Example 1.

[0101] Embodiment 4:

[0102] The enrichment device of this embodiment is different from that of embodiment 1 in that:

[0103] The enrichment tube can also be a U-shaped arc structure, a V-shaped structure or a spiral structure (similar to a spiral spring), and the enrichment fitting groove is designed with a corresponding structure; among which, when the enrichment tube adopts a spiral structure, the enrichment fitting groove can be designed as a cylindrical groove;

[0104] For other structures and control methods, please refer to Example 1.

[0105] The above description is only a detailed description of the preferred embodiments and principles of the present invention. For ordinary technicians in this field, according to the ideas provided by the present invention, there will be changes in the specific implementation methods, and these changes should also be regarded as the protection scope of the present invention.

Claims

1. A control method for an enrichment device, characterized in that: The enrichment device comprises a vacuum chamber and a refrigerator, an enrichment tube, an enrichment driving member and a heater arranged therein, wherein the enrichment driving member is used to drive the enrichment tube to approach or move away from the cold end of the refrigerator, and the heater is used to heat the enrichment tube. The cold end of the refrigerator has an enrichment bonding groove, and the structure of the enrichment bonding groove matches the structure of the enrichment tube, so that the enrichment tube and the enrichment bonding groove are bonded to each other. The cold end of the refrigerator is provided with a clamping piece which is rotatably matched with the notch of the enrichment bonding groove. The clamping piece is used to adjust the position of the enrichment tube so that it fits the surface between the enrichment bonding groove. The control method comprises the following steps: S1. According to N The boiling point of the substance being measured is used to calculate the refrigeration temperature of the enrichment device. T 1. Desorption temperature T 2. Vacuum degree of vacuum chamber P ; Among them, the cooling temperature T 1 is: ； Desorption temperature T 2 is: ； T i For the i The boiling point of the substance being tested, i∈[1, N ], N is an integer greater than 1; is a first preset temperature difference; Vacuum degree of vacuum chamber P for: ； in, A , B , C is the fitting coefficient, T 0 is the ambient temperature; S2, wait for the vacuum chamber to reach the vacuum degree P , start the refrigerator; S3, the enrichment driving member drives the enrichment tube to fit the enrichment fitting groove, and when the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate from the first target position to the second target position; S4, when the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate from the second target position to the first target position, the enrichment driving member drives the enrichment tube to separate from the enrichment bonding tank and starts the heater, and when the temperature collected by the temperature sensor reaches the third target temperature, all the measured substances are desorbed; The second target temperature , the third target temperature ; is the second preset temperature difference, ; S5, repeating the above steps S3 to S4 to achieve enrichment and desorption cycles.

2. The control method according to claim 1, characterized in that: The step S1 also includes: according to the refrigeration temperature T 1. Desorption temperature T 2 Calculate the heating rate of the heater K : ； in, L To enrich the driving stroke of the driving parts, v is the driving speed of the enrichment driving member.

3. The control method according to claim 1, characterized in that: The two ends of the enrichment tube are respectively provided with limit blocks, and the positioning pieces correspond to the limit blocks one by one; When the positioning member rotates to the first target position, the enrichment tube is prevented from entering the enrichment bonding tank or away from the enrichment bonding tank; When the clamping member rotates to the second target position, the clamping member abuts against the limiting block, so that the enrichment tube and the enrichment bonding groove are bonded to each other.

4. The control method according to claim 3, characterized in that: The rotation of the locking member is driven by a locking driving member; The enrichment device also includes a controller, which is connected to the refrigerator, the enrichment drive, the heater, and the positioning drive by signals.

5. The control method according to claim 4, characterized in that: The enrichment tube is provided with a temperature sensor, and the temperature sensor is connected to the controller signal; When the temperature collected by the temperature sensor reaches the first target temperature, the controller controls the positioning driving member to drive the positioning member to rotate to the second target position; When the temperature collected by the temperature sensor reaches the second target temperature and lasts for a preset time, the controller controls the positioning driving member to drive the positioning member to rotate to the first target position; The first target temperature is higher than the second target temperature, and the second target temperature is within a preset temperature range of the cooling temperature of the refrigerator.

6. The control method according to any one of claims 2 to 5, characterized in that: The enrichment tube is an arc-shaped structure, a V-shaped structure or a spiral structure.

7. The control method according to any one of claims 2 to 5, characterized in that: An elastic connecting piece is provided between the enrichment tube and the enrichment driving piece.

8. The control method according to any one of claims 2 to 5, characterized in that: The vacuum chamber is provided with an anti-condensation and frost protection gas circuit; The anti-condensation and frost protection gas circuit includes an air compressor, a filter, a normally open solenoid valve, a one-way valve and an air outlet end head which are arranged in sequence along the flow direction of the gas circuit. The filter is used to remove water, oil and particulate matter, and the air outlet of the air outlet end head faces the cold end of the refrigerator.

9. The control method according to any one of claims 2 to 5, characterized in that: The vacuum chamber is connected to a vacuum pump.

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