Capillary flow resistance measurement system and method

Abstract

The application relates to the technical field of capillary tubes, and provides a capillary flow resistance measuring system and a measuring method.The disclosed measuring system comprises a Dewar, a liquid storage tank, a pump, a mass flowmeter and a connecting pipeline.The Dewar has an inner cavity, the liquid storage tank is used for storing liquid refrigerant, the liquid storage tank is communicated with the inner cavity, the connecting pipeline is detachably connected with the Dewar, a first port of the connecting pipeline extends into the inner cavity, the first port is used for connecting the capillary tube, the pump and the mass flowmeter are arranged in the connecting pipeline, and the pump and the mass flowmeter are located outside the Dewar.The application can solve the problem that in the related art, the flow resistance of the capillary tube is affected by temperature and refrigerant types, the flow resistance of the capillary tube in the liquid refrigerant with a low flow temperature is measured by using a flow resistance calculation method or a room temperature measurement method, and the measurement precision is low.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of capillary tubes, and in particular to a capillary flow resistance measuring system and method. BACKGROUND

[0002] Using liquid refrigerants such as liquid helium, liquid nitrogen, etc. for refrigeration is a common refrigeration method, and can be used for pre-cooling of dilution refrigerators, adiabatic demagnetization refrigerators, etc. In the process of using liquid refrigerants for refrigeration, the evaporation of the liquid refrigerant will cause a decrease in the amount of the liquid refrigerant, so the liquid refrigerant needs to be replenished. In the process of replenishing the liquid refrigerant, a flow resistance element is usually used to control the replenishment rate of the liquid refrigerant to achieve a balance between the evaporation amount and the replenishment amount of the liquid refrigerant.

[0003] As a flow resistance element, a capillary tube is widely used due to its simple structure and good stability. However, the flow resistance of the capillary tube is not adjustable, so before use, the flow resistance of the capillary tube is usually measured to ensure the replenishment rate of the liquid refrigerant when the capillary tube is used to replenish the liquid refrigerant.

[0004] The related art usually uses a flow resistance calculation method or a room temperature measurement method to determine the flow resistance of the capillary tube when the liquid refrigerant flows through it. The flow resistance obtained using the flow resistance calculation method has an error with the actual flow resistance of the capillary tube. Since the flow resistance of the capillary tube is different at different temperatures and when different types of media flow through it, and the temperature of the liquid refrigerant is usually low, the flow resistance obtained using the room temperature measurement method also has an error with the flow resistance of the capillary tube when the liquid refrigerant at a low temperature flows through it. SUMMARY

[0005] The present application provides a capillary flow resistance measuring system and method to solve the problem of low measurement accuracy of the flow resistance of the capillary tube when the flow resistance calculation method or the room temperature measurement method is used to measure the flow resistance of the capillary tube when the liquid refrigerant at a low temperature flows through it in the related art.

[0006] The present application provides a capillary flow resistance measuring system, which comprises a Dewar, a liquid storage tank, a pump, a mass flow meter and a communication pipeline, wherein:

[0007] The Dewar has an inner cavity, the liquid storage tank is used to store the liquid refrigerant, the liquid storage tank is in communication with the inner cavity, the communication pipeline is detachably connected to the Dewar, a first port of the communication pipeline extends into the inner cavity, the first port is used to communicate with the capillary tube, the pump and the mass flow meter are both arranged in the communication pipeline, and the pump and the mass flow meter are both located outside the Dewar.

[0008] The measurement system further comprises a gas storage tank for storing gaseous refrigerant medium, and the gas storage tank is in communication with the communication pipeline.

[0009] The dewar is provided with an exhaust structure for exhausting gas in the inner cavity.

[0010] The communication pipeline comprises a gas conveying pipe and a communication pipe, one end of the gas conveying pipe is detachably connected with the dewar, the end of the gas conveying pipe located in the inner cavity forms the first port, and the other end of the gas conveying pipe is in communication with the gas storage tank.

[0011] The communication pipe is in communication with the gas conveying pipe, and the communication position of the communication pipe and the gas conveying pipe is located outside the dewar, and the pump and the mass flow meter are arranged on the communication pipe.

[0012] The gas conveying pipe and the dewar are plug-in connectable, so that the gas conveying pipe is detachably connected with the dewar, and the first port is used for detachably connecting with the capillary.

[0013] The communication pipe and the gas conveying pipe are detachably connected.

[0014] The measurement system further comprises a second valve and a second pressure detection mechanism, and the second valve and the second pressure detection mechanism are arranged on the gas conveying pipe and located between the communication position and the gas storage tank.

[0015] The measurement system further comprises a third valve and a third pressure detection mechanism, and the third valve and the third pressure detection mechanism are arranged on the communication pipe.

[0016] The dewar comprises an inner layer and an outer layer, the outer layer is arranged around the inner layer, and a sandwich layer is formed between the inner layer and the outer layer, the sandwich layer is in communication with the communication pipeline through a vacuumizing pipe, so that the sandwich layer is in communication with the inlet of the pump, and the vacuumizing pipe is provided with a fourth valve.

[0017] The dewar further comprises a heat shield, and the heat shield is arranged between the inner layer and the outer layer and around the inner layer.

[0018] The measurement system comprises a liquid conveying pipe, a first valve and a first pressure detection mechanism, the liquid storage tank and the inner cavity are in communication through the liquid conveying pipe, and the first valve and the first pressure detection mechanism are arranged on the liquid conveying pipe.

[0019] The measuring system provided in the present application further comprises a temperature detection mechanism, which is located in the inner cavity, and the distance between the temperature detection mechanism and the bottom wall of the Dewar is greater than or equal to the distance between the first port and the bottom wall of the Dewar.

[0020] The present application provides a method for measuring capillary flow resistance, which is applied to the measuring system as described above, and the method comprises the following steps:

[0021] mounting the capillary on the first port;

[0022] placing the capillary in the inner cavity;

[0023] opening the liquid storage tank to introduce the liquid refrigerant into the inner cavity, so that the liquid refrigerant reaches a preset liquid level;

[0024] opening the pump and the mass flow meter to read the first reading of the mass flow meter;

[0025] closing the pump, the mass flow meter and the liquid storage tank.

[0026] The measuring system provided in the present application further comprises a gas storage tank, which is used for storing gaseous refrigerant, and the gas storage tank is in communication with the communication pipeline, and the Dewar is provided with an exhaust structure for exhausting gas in the inner cavity.

[0027] After the capillary is placed in the inner cavity, the method further comprises the following steps before the liquid storage tank is opened:

[0028] opening the gas storage tank to introduce gaseous refrigerant into the capillary.

[0029] After the capillary is mounted on the first port, the method further comprises the following steps:

[0030] opening the gas storage tank;

[0031] placing the outlet of the capillary in the intermediate liquid to observe whether bubbles overflow from the outlet of the capillary, and if bubbles overflow, placing the capillary in the inner cavity.

[0032] The communication pipeline comprises a gas conveying pipe and a communication pipe, the gas conveying pipe is detachably connected with the Dewar, one end of the gas conveying pipe is located in the inner cavity, and the port located in the inner cavity forms the first port, and the other end of the gas conveying pipe is in communication with the gas storage tank.

[0033] The communicating pipe is in communication with the gas conveying pipe, and the communicating position of the communicating pipe and the gas conveying pipe is located outside the Dewar, the pump and the mass flow meter are arranged in the communicating pipe;

[0034] Wherein, after the opening of the liquid storage tank, the liquid refrigerant medium is introduced into the inner cavity, and the liquid refrigerant medium reaches the preset liquid level, before the opening of the pump, the measurement method further comprises:

[0035] Close the gas storage tank.

[0036] According to the measurement method provided in the application, the measurement system further comprises a second valve and a second pressure detection mechanism, both of which are arranged in the gas conveying pipe and located between the communicating position and the gas storage tank;

[0037] Wherein, during the process of opening the gas storage tank and introducing the gaseous refrigerant medium into the capillary, the opening degree of the second valve is adjusted to control the pressure in the gas conveying pipe within a second preset pressure range.

[0038] According to the measurement method provided in the application, after the reading of the first indication of the mass flow meter, the measurement method further comprises: replacing the capillary,

[0039] Wherein, the replacing of the capillary comprises:

[0040] Close the pump;

[0041] Open the gas storage tank and introduce the gaseous refrigerant medium into the capillary;

[0042] Take the capillary out of the inner cavity;

[0043] Replace the capillary connected to the first port;

[0044] Place the replaced capillary in the inner cavity.

[0045] According to the measurement method provided in the application, after the closing of the pump, the mass flow meter and the liquid storage tank, the measurement method further comprises:

[0046] Open the gas storage tank and introduce the gaseous refrigerant medium into the capillary until the liquid refrigerant medium in the inner cavity is vaporized;

[0047] Close the gas storage tank.

[0048] According to the measurement method provided in the present application, the Dewar includes an inner layer and an outer layer, the outer layer is arranged around the inner layer, and a sandwich layer is formed between the inner layer and the outer layer, the sandwich layer is communicated with the inlet of the pump through a vacuumizing pipe, and the vacuumizing pipe is provided with a fourth valve;

[0049] Before the opening of the liquid storage tank, the measurement method further includes:

[0050] The fourth valve is opened;

[0051] The pump is started until the sandwich layer is in a vacuum state;

[0052] The pump and the fourth valve are closed.

[0053] According to the measurement method provided in the present application, after the capillary tube is placed in the inner cavity, before the opening of the liquid storage tank, the flow resistance measurement method further includes:

[0054] The pump is started to extract the normal-temperature gas in the inner cavity through the capillary tube;

[0055] The mass flow meter is started, and a second reading of the mass flow meter is read;

[0056] The pump and the mass flow meter are closed.

[0057] According to the measurement method provided in the present application, the measurement system further includes a temperature detection mechanism, the temperature detection mechanism is located in the inner cavity, and the distance between the temperature detection mechanism and the bottom wall of the Dewar is greater than or equal to the distance between the first port and the bottom wall of the Dewar;

[0058] During the process of introducing the liquid refrigerant medium into the inner cavity, in a case where the temperature detected by the temperature detection mechanism is less than or equal to a first preset temperature, the liquid storage tank is closed, and in a case where the temperature detected by the temperature detection mechanism is greater than or equal to a second preset temperature, the liquid storage tank is opened, the second preset temperature is greater than the first preset temperature, so that the liquid refrigerant medium reaches a preset liquid level.

[0059] In the embodiments of the present application, the capillary tube is immersed in the liquid refrigerant medium by filling the liquid refrigerant medium into the Dewar, the liquid refrigerant medium in the capillary tube is extracted by the pump, the flow rate of the liquid refrigerant medium is measured by the mass flow meter, and the flow resistance of the capillary tube in the temperature zone of the liquid refrigerant medium is calculated more accurately. As can be seen, the present application can solve the problem in the related art that the flow resistance of the capillary tube is affected by temperature and the type of refrigerant, and the measurement accuracy is low when the flow resistance calculation method or the room temperature measurement method is used to measure the flow resistance of the capillary tube in the liquid refrigerant medium with a lower flow temperature. BRIEF DESCRIPTION OF DRAWINGS

[0060] In order to more clearly illustrate the technical solutions in the application or the prior art, the drawings needed to be used in the embodiments or prior art description will be briefly introduced. Obviously, the drawings in the following description are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without any creative effort on the basis of these drawings.

[0061] Fig. 1 is a structural schematic diagram of a capillary flow resistance measuring system provided by the present application;

[0062] Fig. 2 is a structural schematic diagram of a Dewar provided by the present application;

[0063] Fig. 3 is a flow chart of a capillary flow resistance measuring method provided by the present application.

[0064] Reference signs:

[0065] 100 - Dewar, 110 - inner cavity, 120 - inner layer, 130 - outer layer, 140 - heat shield, 150 - end cover,

[0066] 200 - liquid storage tank, 210 - first on-off valve,

[0067] 300 - pump,

[0068] 400 - mass flow meter,

[0069] 500 - gas storage tank, 510 - second on-off valve,

[0070] 610 - liquid delivery pipe, 620 - gas delivery pipe, 630 - communication pipe, 640 - vacuum extraction pipe,

[0071] 710 - first valve, 720 - second valve, 730 - third valve, 740 - fourth valve,

[0072] 810 - first pressure detection mechanism, 820 - second pressure detection mechanism, 830 - third pressure detection mechanism, 840 - fourth pressure detection mechanism,

[0073] 900 - temperature detection mechanism,

[0074] 1000 - capillary. DETAILED DESCRIPTION

[0075] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely below in combination with the drawings in the present application. Obviously, the described embodiments are only some of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative work fall within the scope of protection of the present application.

[0076] Please refer to Figs. 1-2 The present application discloses a capillary flow resistance measuring system for measuring the flow resistance of a capillary tube, the flow resistance of the capillary tube refers to the ratio of the pressure difference and the flow rate in the capillary tube, R=△P / Q, R refers to the flow resistance, △P refers to the pressure difference, and Q refers to the flow rate. The pressure difference in the present application is 1 bar. The flow resistance is related to the viscosity of the fluid, the length and the radius of the capillary tube. The viscosity of the fluid is affected by the type and the temperature of the fluid, that is, the flow resistance of the capillary tube is different when different types of fluids flow in the capillary tube or when the temperature of the capillary tube is different. The measuring system disclosed in the present application comprises a dewar 100, a liquid storage tank 200, a pump 300, a mass flow meter 400 and a communication pipeline.

[0077] The dewar 100 has an inner cavity 110, the liquid storage tank 200 is used for storing a low-temperature refrigerant medium, the low-temperature refrigerant medium has a low temperature, for example, liquid helium or liquid nitrogen, the liquid storage tank 200 is in communication with the inner cavity 110, so as to fill the inner cavity 110 with the low-temperature refrigerant medium, the communication pipeline is detachably connected with the dewar 100, a first port of the communication pipeline extends into the inner cavity 110, and the first port of the communication pipeline is used for connecting a capillary tube 1000. When the capillary tube 1000 is connected to the first port, the communication pipeline and the capillary tube 1000 are in communication. The pump 300 and the mass flow meter 400 are both arranged in the communication pipeline, so that the inner cavity 110, the capillary tube 1000, the communication pipeline, the pump 300 and the mass flow meter 400 form a passage, and the pump 300 and the mass flow meter 400 are both located outside the dewar 100.

[0078] Optionally, the pump 300 can be a mechanical dry pump or a molecular pump, and any brand of pump 300 (for example, Agilent) can be used. Of course, the pump 300 can also use a pump body of other types except an oil pump. Optionally, the inlet of the pump 300 can be in communication with the first port, and the mass flow meter 400 can be in communication with the outlet of the pump 300.

[0079] When the flow resistance of the capillary tube 1000 in the temperature zone of the liquid refrigerant medium needs to be measured, the capillary tube 1000 is connected to the first port and placed in the inner cavity 110, the liquid refrigerant medium is introduced into the inner cavity 110 through the liquid storage tank 200 until the capillary tube 1000 is immersed in the liquid refrigerant medium, the pump 300 is started to extract the liquid refrigerant medium, the liquid refrigerant medium enters the passage formed by the capillary tube 1000, the connecting pipeline, the pump 300 and the mass flow meter 400, the reading of the mass flow meter 400 is observed, after the reading is stable, the first reading is recorded, the first reading is the flow capacity of the capillary tube 1000 in the temperature zone of the liquid refrigerant medium, and the flow resistance of the capillary tube 1000 is calculated according to the flow capacity of the liquid refrigerant medium, the specific calculation method is the prior art, which will not be described here.

[0080] It should be noted that different liquid refrigerant media have different temperatures, for example, the temperature of liquid helium is about 4K, and the temperature of liquid nitrogen is about 77K, different types of liquid refrigerant media are filled into the inner cavity 110, and different types of liquid refrigerant media flow through the capillary tube 1000, so that the flow resistance of the capillary tube 1000 in different temperature zones can be measured, for example, liquid helium is introduced into the inner cavity 110, and the flow resistance of the capillary tube 1000 in the liquid helium temperature zone can be measured using the above measurement system when the capillary tube 1000 is immersed in the liquid helium; liquid nitrogen is introduced into the inner cavity 110, and the flow resistance of the capillary tube 1000 in the liquid nitrogen temperature zone can be measured using the above measurement system when the capillary tube 1000 is immersed in the liquid nitrogen.

[0081] When the flow resistance of the capillary tube 1000 in the temperature zone of the liquid refrigerant medium and flowing through the liquid refrigerant medium is measured using the measurement system of the present application, the capillary tube 1000 is immersed in the liquid refrigerant medium, and the internal flow is the liquid refrigerant medium, so that the temperature of the capillary tube 1000 is close to the temperature of the liquid refrigerant medium, therefore, the accurate flow resistance of the capillary tube 1000 in the temperature zone of the liquid refrigerant medium and flowing through the liquid refrigerant medium can be measured, and the calculation error and measurement error caused by the flow resistance calculation method and room temperature measurement method in the related art are avoided.

[0082] In the embodiment of the present application, the Dewar 100 is filled with liquid refrigerant medium, the capillary 1000 is immersed in the liquid refrigerant medium, the liquid refrigerant medium in the capillary 1000 is pumped out by the pump 300, the liquid refrigerant medium flows through the capillary 1000, and the temperature of the capillary 1000 is close to or the same as that of the liquid refrigerant medium. The mass flow meter 400 measures the flow rate of the liquid refrigerant medium, and the flow resistance of the capillary 1000 in the liquid refrigerant medium temperature zone is calculated based on the flow rate of the liquid refrigerant medium. Therefore, the present application can solve the problem of low measurement accuracy of the flow resistance of the capillary in the liquid refrigerant medium with low flow temperature by using the flow resistance calculation method or the room temperature measurement method in the related art.

[0083] Of course, the present application can also measure the flow resistance of the capillary 1000 in the normal temperature zone. When it is necessary to measure the flow resistance of the capillary 1000 in the normal temperature zone, the capillary 1000 is connected to the first port and placed in the inner cavity 110, the pump 300 is started to pump out the normal temperature gas (for example, air) in the inner cavity 110, the mass flow meter 400 records the flow rate of the normal temperature gas, and the flow resistance of the capillary 1000 in the normal temperature zone is calculated based on the flow rate of the normal temperature gas.

[0084] In a further technical solution, the measurement system can further include a gas storage tank 500. The gas storage tank 500 is used to store gaseous refrigerant medium. The gas storage tank 500 is in communication with the communication pipeline, so as to introduce the gaseous refrigerant medium into the capillary 1000 and the inner cavity 110 through the communication pipeline. It should be noted that the liquid refrigerant medium stored in the liquid storage tank 200 and the gaseous refrigerant medium stored in the gas storage tank 500 can be the same kind of refrigerant medium. For example, when liquid helium is stored in the liquid storage tank 200, helium gas can be stored in the gas storage tank 500. For another example, when liquid nitrogen is stored in the liquid storage tank 200, nitrogen gas can be stored in the gas storage tank 500. 4 He gas, and for another example, when liquid nitrogen is stored in the liquid storage tank 200, nitrogen gas can be stored in the gas storage tank 500.

[0085] The Dewar 100 is provided with an exhaust structure for exhausting the gas in the inner cavity 110. During the process of introducing the gaseous refrigerant medium into the capillary 1000 and the inner cavity 110, the gaseous refrigerant medium enters the inner cavity 110 through the capillary 1000. The exhaust structure can exhaust the gas in the inner cavity 110, so as to avoid the problem that the pressure in the inner cavity 110 is too high during the process of introducing the gaseous refrigerant medium into the capillary 1000, which causes a safety accident, thereby improving the safety of the measurement system.

[0086] Optionally, the exhaust structure can be an exhaust hole arranged on the dewar 100, the exhaust hole being in communication with the external environment and the inner cavity 110 of the dewar 100, and the exhaust structure can also be a safety valve arranged on the dewar 100, the safety valve being opened to communicate the external environment and the inner cavity 110 of the dewar 100 when the pressure in the inner cavity 110 reaches the third preset pressure.

[0087] In this case, by introducing the gaseous refrigerant into the communication pipeline through the gas storage tank 500, the gaseous refrigerant can also flow in the capillary tube 1000 connected to the first port and the inner cavity 110, and the air in the capillary tube 1000 and the inner cavity 110 is discharged, preventing the problem of clogging of the capillary tube 1000 and icing of the inner wall of the inner cavity 110 after the liquid refrigerant is introduced into the inner cavity 110, because the liquid refrigerant is a low-temperature refrigerant, the temperature is low, and the low-temperature environment in the inner cavity 110 causes the air in the capillary tube 1000 to condense, thereby causing the capillary tube 1000 to be blocked and the inner wall of the inner cavity 110 to be iced.

[0088] Specifically, the communication pipeline can include a gas delivery pipe 620 and a communication pipe 630, the gas delivery pipe 620 can be detachably connected with the dewar 100, one end of the gas delivery pipe 620 can be located in the inner cavity 110, and the port of the gas delivery pipe 620 located in the inner cavity 110 forms the first port, and the other end of the gas delivery pipe 620 can be in communication with the gas storage tank 500.

[0089] The communication pipe 630 can be in communication with the gas delivery pipe 620, and the pump 300 and the mass flow meter 400 can be arranged in the communication pipe 630. In this case, the pump 300 and the mass flow meter 400 are arranged in the communication pipe 630, and the communication pipe 630 realizes the communication of the pump 300 and the mass flow meter 400 with the capillary tube 1000 by communicating with the gas delivery pipe 620.

[0090] In an alternative embodiment, the communication position of the communication pipe 630 and the gas delivery pipe 620 can be located inside the dewar 100. In this structure, the gas delivery pipe 620 and the communication pipe 630 both need to pass through the dewar 100, so a hole is needed to be formed on the dewar 100 for the gas delivery pipe 620 and the communication pipe 630 to pass through.

[0091] In the embodiments of the present application, the communication position of the communication pipe 630 and the gas delivery pipe 620 can be located outside the dewar 100. In this case, the communication position is located outside the dewar 100, and a hole does not need to be formed on the dewar 100 for the communication pipe 630 to pass through, thereby reducing the number of holes on the dewar 100, improving the structural strength of the dewar 100, and reducing the heat leakage of the dewar 100.

[0092] When the flow resistance of the capillary tube 1000 needs to be measured, the capillary tube 1000 needs to be placed into the inner cavity 110 of the dewar 100. For this purpose, in an alternative embodiment, the dewar 100 can be provided with a shell and an end cover 150, the end cover 150 can be detachably connected with the shell, after the end cover 150 and the shell are separated, the capillary tube 1000 is placed into the inner cavity 110, and then the end cover 150 and the shell are connected.

[0093] In another alternative embodiment, the gas supply pipe 620 and the dewar 100 can be connected in a pluggable manner, so that the gas supply pipe 620 and the dewar 100 can be detachably connected. Specifically, an opening can be provided on the dewar 100, the capillary tube 1000 and the communication pipeline can be inserted into the inner cavity 110 through the opening, or part of the communication pipeline and the capillary tube 1000 can be taken out of the inner cavity 110 through the opening, so as to realize the pluggable connection of the gas supply pipe 620 and the dewar 100.

[0094] The first port is used for detachable connection with the capillary tube 1000. Alternatively, the capillary tube 1000 can be connected to the first port by soldering. In this connection mode, heating can separate the capillary tube 1000 and the first port. For example, using a heat gun or other tools to reheat the connection position of the capillary tube 1000 and the first port can complete the separation of the capillary tube 1000 and the first port.

[0095] In this case, the pluggable connection facilitates the operation of placing the capillary tube 1000 into the inner cavity 110 or taking it out of the inner cavity 110. When the capillary tube 1000 to be measured needs to be replaced, the gas supply pipe 620 can be directly pulled out of the dewar 100, which is simple and convenient.

[0096] In order to facilitate the plugging and unplugging operation of the gas supply pipe 620, the communication pipeline 630 and the gas supply pipe 620 can be detachably connected. Disconnecting the communication pipeline 630 and the gas supply pipe 620 facilitates the plugging and unplugging operation of the gas supply pipe 620. Alternatively, the communication pipeline 630 and the gas supply pipe 620 can be connected in a clamping sleeve connection manner to realize detachable connection. In the embodiment of the present application, the third valve 730 and the second pressure detection mechanism 820 (see below) can be connected in a clamping sleeve connection manner, so as to realize the detachable connection of the communication pipeline 630 and the gas supply pipe 620. Of course, the communication pipeline 630 and the gas supply pipe 620 can also be connected by other pipeline connection manners, which are not limited by comparison.

[0097] In a further technical solution, the measuring system can further comprise a second valve 720 and a second pressure detecting mechanism 820, which can be both arranged in the gas delivery pipe 620 and located between the communication position and the gas tank 500. The gas delivery pipe 620 can further be provided with a second on-off valve 510, which is an on-off valve of the gas tank 500, and the opening and closing of the gas tank 500 can be controlled by the opening and closing of the second on-off valve 510. The gas delivery pipe 620 can further be provided with a fourth pressure detecting mechanism 840 for measuring the pressure of the gas tank 500.

[0098] In this case, the opening and closing of the gas tank 500 can be controlled by the second on-off valve 510, and the pressure in the gas delivery pipe 620 during the process of filling the gaseous refrigerant can be adjusted by adjusting the opening degree of the second valve 720. The pressure in the gas delivery pipe 620 can be detected by the second pressure detecting mechanism 820 to determine whether the gas delivery pipe 620 is under positive pressure, thereby ensuring the smoothness of the gas delivery process.

[0099] Optionally, the pressure in the gas delivery pipe 620 during the process of filling the gaseous refrigerant can be 2 bar to ensure that the gas delivery pipe 620 is under positive pressure. The second pressure detecting mechanism 820 can be a pressure sensor.

[0100] The measuring system can further comprise a third valve 730 and a third pressure detecting mechanism 830, which can be both arranged in the communication pipe 630. The third pressure detecting mechanism 830 can be used to detect the pressure of the communication pipe 630, and the pressure in the communication pipe 630 can be controlled by adjusting the opening degree of the third valve 730. For example, when the liquid refrigerant or the normal-temperature gas in the inner cavity 110 is extracted by the pump 300, the third valve 730 can be adjusted to control the pressure in the communication pipe 630 to be less than or equal to 1.4 bar.

[0101] The third valve 730 can control the conduction and blockage of the communication pipe 630. During the process of opening the pump 300 to extract the liquid refrigerant (or the normal-temperature gas) in the inner cavity 110, the third valve 730 can be opened to make the communication pipe 630 conductive. During this process, the gas tank 500 (i.e., the second on-off valve 510) and the second valve 720 can be closed to avoid the gaseous refrigerant in the gas tank 500 entering the pump 300 and the mass flow meter 400 during the process of extracting the liquid refrigerant, thereby affecting the accuracy of the measurement of the flow resistance. During the process of introducing the gaseous refrigerant into the capillary 1000, the gas tank 500 (i.e., the second on-off valve 510) and the second valve 720 can be opened, and the third valve 730 can be closed to avoid the gaseous refrigerant entering the communication pipe 630 through the gas delivery pipe 620 and then entering the atmosphere through the communication pipe 630, thereby causing waste of the gaseous refrigerant.

[0102] In the above scheme, in the process of measuring the flow resistance of the capillary 1000 in the temperature zone of the liquid refrigerant, the dewar 100 needs to be filled with liquid refrigerant. In order to better store the liquid refrigerant in the inner cavity 110 and maintain the low-temperature environment in the inner cavity 110, in the embodiment of the present application, the dewar 100 can include an inner layer 120 and an outer layer 130. The outer layer 130 can be arranged around the inner layer 120, and a sandwich layer can be formed between the inner layer 120 and the outer layer 130. The sandwich layer can be communicated with the connecting pipeline through the vacuum extraction pipe 640, the vacuum extraction pipe 640 is communicated with the connecting pipeline 630, and the vacuum extraction pipe 640 is communicated with the pump 300, so that the sandwich layer is communicated with the inlet of the pump 300. The vacuum extraction pipe 640 can be provided with a fourth valve 740.

[0103] In this case, the air in the sandwich layer can be extracted by the pump 300, so that the sandwich layer is in a vacuum state, the convection heat loss of the dewar 100 is reduced, the low-temperature environment maintenance time of the dewar 100 is prolonged, the evaporation speed of the liquid refrigerant in the dewar 100 is slowed down, and the storage of the liquid refrigerant is facilitated.

[0104] When the air in the sandwich layer is extracted by the pump 300, the first valve 710 (see below), the first switch valve 210 (see below), the second switch valve 510, the second valve 720 and the third valve 730 can be closed; in the process of filling the gaseous refrigerant, the gas tank 500 is opened (that is, the second switch valve 510 and the second valve 720 are opened, the fourth valve 740 and the third valve 730 can be closed to prevent the gaseous refrigerant from entering the vacuum extraction pipe 640 through the connecting pipeline, so as to enter the sandwich layer, causing waste of the gaseous refrigerant; in the process of extracting the liquid refrigerant (or normal-temperature gas) in the inner cavity 110 by the pump 300, the fourth valve 740 can be closed.

[0105] In a further technical scheme, the dewar 100 can further include a heat shield 140, which can be arranged between the inner layer 120 and the outer layer 130 and around the inner layer 120. In this case, the heat shield 140 can reduce the radiation heat loss of the dewar 100 and further slow down the evaporation speed of the liquid refrigerant in the dewar 100. Optionally, the heat shield 140 can be a cold shield.

[0106] The Dewar 100 can further include an end cover 150, the inner layer 120, the outer layer 130 and the heat shield 140 can be welded on the end cover 150, the inner layer 120, the outer layer 130 and the end cover 150 enclose a sandwich, the heat shield 140 is located between the inner layer 120 and the outer layer 130, and the exhaust structure of the Dewar 100 can also be provided on the end cover 150. The height of the Dewar 100 (the height direction of the Dewar 100 is consistent with the vertical direction) can be greater than or equal to 400 mm, in order to reduce the conduction heat leakage, the pipe diameter of the gas conveying pipe 620 and the liquid conveying pipe 610 (see below) can be designed to be smaller, and the first port of the gas conveying pipe 620 can be adjacent to the bottom wall of the Dewar 100, thereby extending the length of the gas conveying pipe 620, so as to reduce the heat conduction of the gas conveying pipe 620, thereby reducing the conduction heat leakage.

[0107] In the above scheme, the liquid storage tank 200 and the inner cavity 110 are communicated, and specifically, the measurement system can further include a liquid conveying pipe 610, a first valve 710 and a first pressure detection mechanism 810, the liquid storage tank 200 and the inner cavity 110 can be communicated through the liquid conveying pipe 610, and the first valve 710 and the first pressure detection mechanism 810 are both arranged on the liquid conveying pipe 610. The liquid conveying pipe 610 can be provided with a first on-off valve 210, and the first on-off valve 210 controls the opening and closing of the liquid storage tank 200.

[0108] In this case, the filling speed of the liquid refrigerant is determined by the reading of the first pressure detection mechanism 810, and the filling speed of the liquid refrigerant is adjusted by adjusting the opening degree of the first valve 710.

[0109] Optionally, during the process of filling the liquid refrigerant into the inner cavity 110, the liquid storage tank 200 (i.e. the first on-off valve 210 is opened) and the first valve 710 are opened, and the gas storage tank 500 and the second valve 720 can also be opened, and the gaseous refrigerant is filled, and after the liquid refrigerant reaches the preset liquid level, the gas storage tank 500 and the second valve 720 are closed. In this case, the gas in the capillary tube 1000 can be maintained as gaseous refrigerant before the capillary tube 1000 is completely immersed in the liquid refrigerant, preventing the capillary tube 1000 and the communication pipeline from having air inside, which can cause the temperature in the inner cavity 110 to decrease during the process of filling the liquid refrigerant, and the air in the capillary tube 1000 to condense, causing the capillary tube 1000 to be blocked.

[0110] The measurement system can further include a temperature detection mechanism 900, the temperature detection mechanism 900 can be located in the inner cavity 110, and the distance between the temperature detection mechanism 900 and the bottom wall of the Dewar 100 can be greater than or equal to the distance between the first port and the bottom wall of the Dewar 100.

[0111] In an alternative embodiment, the temperature detecting mechanism 900 can be arranged on the inner wall of the dewar 100. In another alternative embodiment, the temperature detecting mechanism 900 can be arranged on the portion of the communication pipeline located in the inner cavity 110. In this structure, the temperature detecting mechanism 900 and the first port are fixed in position, so that after the first port is connected to the capillary 1000, the position relationship between the capillary 1000 and the temperature detecting mechanism 900 is fixed, avoiding the problem that it is difficult to control the position relationship between the temperature detecting mechanism 900 and the capillary 1000 during the process of placing the capillary 1000 into the inner cavity 110.

[0112] Alternatively, the temperature detecting mechanism 900 can be a thermometer. In the case that the liquid refrigerant is liquid helium, the thermometer can be a silicon diode thermometer, a carbon resistor thermometer, or a ruthenium oxide thermometer. Of course, the appropriate temperature detecting mechanism 900 can be selected according to the temperature of the liquid refrigerant, and the specific type of the temperature detecting mechanism 900 is not limited in the present application.

[0113] The height of the temperature detecting mechanism 900 in the vertical direction is higher than the height of the capillary 1000. The temperature detected by the temperature detecting mechanism 900 when it is in contact with the liquid refrigerant is different from the temperature detected when it is not in contact with the liquid refrigerant. Therefore, the liquid level of the liquid refrigerant can be determined by the temperature detected by the temperature detecting mechanism 900, and whether the capillary 1000 is submerged in the liquid refrigerant can be determined.

[0114] For example, in the case that the liquid refrigerant is liquid helium, when the temperature detected by the temperature detecting mechanism 900 is about 4K, it indicates that the liquid level of the liquid refrigerant is level with or higher than the temperature detecting mechanism 900. Since the height of the temperature detecting mechanism 900 is higher than the height of the capillary 1000, it indicates that the capillary 1000 is submerged in the liquid refrigerant. When the temperature detected by the temperature detecting mechanism 900 is greater than 5K, it indicates that the liquid level of the liquid refrigerant is lower than the height of the temperature detecting mechanism 900. At this time, the liquid refrigerant needs to be supplemented.

[0115] Of course, in other embodiments, a liquid level meter can be arranged in the dewar 100 to measure the liquid level of the liquid refrigerant in the inner cavity 110, so as to determine whether the capillary 1000 is submerged in the liquid refrigerant. However, the volume and cost of the temperature detecting mechanism 900 are generally smaller than those of the liquid level meter. Therefore, using the temperature detecting mechanism 900 to determine whether the capillary 1000 is submerged in the liquid refrigerant can reduce the cost of the measurement system and save the internal space of the inner cavity 110.

[0116] The present application also discloses a capillary flow resistance measurement method applied to the above-mentioned measurement system. As shown in Fig. 3 The disclosed measurement method includes:

[0117] S101, install the capillary 1000 to the first port.

[0118] S102, place the capillary 1000 in the inner cavity 110.

[0119] It should be noted that the order of the two steps S101 and S102 is not limited.

[0120] S103, open the liquid storage tank 200, and introduce the liquid refrigerant into the inner cavity 110, so that the liquid refrigerant reaches a preset liquid level, or the liquid level of the liquid refrigerant is higher than or equal to the preset liquid level.

[0121] The height of the preset liquid level in the vertical direction can be higher than the height of the capillary 1000. The liquid refrigerant reaching the preset liquid level indicates that the capillary 1000 is immersed in the liquid refrigerant.

[0122] S104, open the pump 300 and the mass flow meter 400, and read the first reading of the mass flow meter 400.

[0123] It should be noted that after opening the pump 300 and the mass flow meter 400, the reading of the mass flow meter 400 is observed, and after the reading is stable, the first reading is recorded. The first reading is the flow rate of the liquid refrigerant in the liquid refrigerant temperature zone of the capillary 1000.

[0124] S105, close the pump 300, the mass flow meter 400, and the liquid storage tank 200.

[0125] When it is necessary to measure the flow resistance of the capillary 1000 in the liquid refrigerant temperature zone, the first reading is measured according to the above steps, which is the flow rate of the liquid refrigerant in the liquid refrigerant temperature zone of the capillary 1000. According to the flow rate of the liquid refrigerant, the flow resistance of the capillary 1000 is calculated. The specific calculation method is a prior art, which will not be described herein.

[0126] When the flow resistance of the capillary 1000 in the liquid refrigerant temperature zone is measured using the measurement method of the present application, the capillary 1000 is immersed in the liquid refrigerant, and the internal flow is the liquid refrigerant, so that the temperature of the capillary 1000 is close to the temperature of the liquid refrigerant. Therefore, the flow resistance of the capillary 1000 in the liquid refrigerant temperature zone can be measured more accurately, and the error problem caused by using the flow resistance calculation method and the room temperature measurement method in related technologies to measure the flow resistance of the capillary 1000 in the liquid refrigerant temperature zone is avoided.

[0127] In a further technical solution, the measurement system further comprises a gas storage tank 500 for storing gaseous refrigerant, the gas storage tank 500 being in communication with the communication pipeline, and the Dewar 100 being provided with an exhaust structure for exhausting gas in the inner cavity 110.

[0128] Wherein, after the step of placing the capillary tube 1000 in the inner cavity 110, before the step of opening the liquid storage tank 200, the measuring method can further comprise:

[0129] Step A1: opening the gas storage tank 500, and introducing the gaseous refrigerant into the capillary tube 1000.

[0130] In this case, before filling the inner cavity 110 with the liquid refrigerant, the gas storage tank 500 is opened to fill the capillary tube 1000 and the inner cavity 110 with the gaseous refrigerant, and the air in the capillary tube 1000 and the inner cavity 110 is discharged, so that the temperature in the inner cavity 110 does not decrease when the liquid refrigerant is subsequently filled into the inner cavity 110, and the air on the inner wall of the capillary tube 1000 or the inner cavity 110 does not condense into ice, thereby preventing the capillary tube 1000 from being blocked.

[0131] Of course, in order to detect whether the capillary tube 1000 to be measured is unblocked, after the step of installing the capillary tube 1000 in the first port, the measuring method can further comprise:

[0132] Step B1: opening the gas storage tank 500, and introducing the gaseous refrigerant into the capillary tube 1000.

[0133] Step B2: placing the outlet of the capillary tube 1000 in the intermediate liquid, observing whether the outlet of the capillary tube 1000 overflows bubbles, and placing the capillary tube 1000 in the inner cavity 110 if bubbles overflow.

[0134] If the outlet of the capillary tube 1000 does not overflow bubbles, it indicates that the capillary tube 1000 is blocked, and the capillary tube 1000 can be repaired or replaced.

[0135] The intermediate liquid can be alcohol or other liquids that do not react with the gaseous refrigerant. If bubbles overflow from the outlet of the capillary tube 1000 in the intermediate liquid, it indicates that the capillary tube 1000 is unblocked, and then the flow resistance of the capillary tube 1000 can be measured.

[0136] In this case, not only can the capillary tube 1000 be detected for being unblocked, but also the capillary tube 1000 can be cleaned by the gaseous refrigerant, so that the capillary tube is kept unblocked and clean.

[0137] It should be noted that the gaseous refrigerant can be filled into the inner cavity 110 until the liquid refrigerant reaches a preset liquid level, so that the capillary tube 1000 and the connecting pipeline do not have air inside, and the temperature in the inner cavity 110 does not decrease during the process of filling the liquid refrigerant, so that the air in the capillary tube 1000 does not condense, and the capillary tube 1000 is not blocked.

[0138] The communication pipeline can include a gas delivery pipe 620 and a communication pipe 630. The gas delivery pipe 620 is detachably connected to the dewar 100. One end of the gas delivery pipe 620 can be located in the inner cavity 110, and the port of the gas delivery pipe 620 located in the inner cavity 110 forms a first port. The other end of the gas delivery pipe 620 can be in communication with the gas storage tank 500.

[0139] The communication pipe 630 can be in communication with the gas delivery pipe 620, and the communication position of the communication pipe 630 and the gas delivery pipe 620 can be located outside the dewar 100. The pump 300 and the mass flow meter 400 can be arranged in the communication pipe 630.

[0140] After the step of opening the gas storage tank 200 and introducing the liquid refrigerant medium into the inner cavity 110 to reach a preset liquid level, the flow resistance measurement method further includes the following steps before the step of opening the pump 300:

[0141] Step C1: closing the gas storage tank 500.

[0142] In this case, the gaseous refrigerant medium in the gas storage tank 500 is prevented from entering the pump 300 and the mass flow meter 400 during the process of extracting the liquid refrigerant medium, thereby affecting the accuracy of measuring the flow resistance.

[0143] In a further technical solution, the measurement system can further include a second valve 720 and a second pressure detection mechanism 820. The second valve 720 and the second pressure detection mechanism 820 are both arranged on the gas delivery pipe 620 and are both located between the communication position and the gas storage tank 500. A second on-off valve 510 can be arranged on the gas delivery pipe 620. The opening and closing of the second on-off valve 510 controls the opening and closing of the gas storage tank 500. When the second on-off valve 510 is opened, the gas storage tank 500 is opened. When the second on-off valve 510 is closed, the gas storage tank 500 is closed.

[0144] During the process of opening the gas storage tank 500 and introducing the gaseous refrigerant medium into the capillary 1000, the pressure in the gas delivery pipe 620 can be controlled within a second preset pressure range by adjusting the opening degree of the second valve 720, for example, the pressure in the gas delivery pipe 620 can be about 2 bar.

[0145] In the above step C1, the second valve 720 is closed at the same time as the gas storage tank 500 is closed (i.e., the second on-off valve 510 is closed).

[0146] The measurement system can further include a third valve 730 and a third pressure detection mechanism 830. The third valve 730 and the third pressure detection mechanism 830 can be arranged in the communication pipe 630.

[0147] In the step S104 described above, the third valve 730 is slowly opened while the pump 300 is on, so that the indication of the third pressure detecting mechanism 830 is less than or equal to 1.4 bar.

[0148] After the step of reading the first indication of the mass flow meter 400, the flow resistance measuring method can further include replacing the capillary tube 1000.

[0149] The step of replacing the capillary tube 1000 can include:

[0150] Step D1: turn off the pump 300.

[0151] In the scheme described above, the communication pipe is provided with the third valve 730, so the step D1 can also be: turning off the third valve 730. In this way, the pump 300 does not need to be frequently turned on and off.

[0152] Step D2: turn on the gas tank 500 to introduce the gaseous refrigerant into the capillary tube 1000.

[0153] In the step D2, the second valve 720 is also opened when the gas tank 500 is turned on, and the indication of the second pressure detecting mechanism 820 is maintained at about 2 bar by controlling the opening degree of the second valve 720, so as to ensure that the pressure in the gas delivery pipe 620 is positive.

[0154] Step D3: remove the capillary tube 1000 from the inner cavity 110.

[0155] The communication pipe and the Dewar 100 can be connected in a pluggable manner to realize detachable connection of the communication pipe and the Dewar 100. The Dewar 100 can be provided with an opening through which the communication pipe and the capillary tube 1000 pass. In this way, only the communication pipe located in the Dewar 100 and the capillary tube 1000 connected to the first port need to be pulled out.

[0156] Step D4: replace the capillary tube 1000 connected to the first port.

[0157] The capillary tube 1000 can be connected to the first port by soldering. The connection position of the capillary tube 1000 and the first port can be re-heated using a hot air gun or other tools to separate the old capillary tube 1000 from the first port, and then a new capillary tube 1000 is connected to the first port by soldering.

[0158] Step D5: place the replaced capillary tube 1000 in the inner cavity 110.

[0159] Then the steps S103, S104, etc. described above can be repeated.

[0160] In this case, the flow resistance of different capillary tubes 1000 in the temperature zone of the liquid refrigerant can be measured.

[0161] The Dewar 100 can include an inner layer 120 and an outer layer 130, the outer layer 130 can be arranged around the inner layer 120, and a sandwich layer can be formed between the inner layer 120 and the outer layer 130, the sandwich layer can be communicated with the inlet of the pump 300 through the vacuum extraction pipe 640, and the fourth valve 740 can be arranged on the vacuum extraction pipe 640.

[0162] Before the step of opening the liquid storage tank 200, the measuring method can further include:

[0163] Step E1: open the fourth valve 740.

[0164] In step E1, the first valve 710, the first switch valve 210, the second switch valve 510, the second valve 720 and the third valve 730 can be closed.

[0165] Step E2: start the pump 300 until the sandwich layer is in a vacuum state.

[0166] Step E3: close the pump 300 and the fourth valve 740.

[0167] In this case, the convection heat loss of the Dewar 100 can be reduced, the low-temperature environment maintenance time in the Dewar 100 can be prolonged, and the evaporation speed of the liquid refrigerant in the Dewar 100 can be slowed down, which is beneficial to the storage of the liquid refrigerant.

[0168] Of course, in other embodiments, steps E1, E2 and E3 can be performed before the step of installing the capillary tube 1000 on the first port or before the step of placing the capillary tube 1000 in the inner cavity 110.

[0169] After the step of placing the capillary tube 1000 in the inner cavity 110, before the step of opening the liquid storage tank 200, the measuring method can further include:

[0170] Step F1: start the pump 300 to extract the normal-temperature gas in the inner cavity 110 through the capillary tube 1000;

[0171] Optionally, the normal-temperature gas can be air. In this process, the third valve 730 can be opened, and the first valve 710, the first switch valve 210, the second switch valve 510, the second valve 720 and the fourth valve 740 can be closed.

[0172] Step F2: start the mass flow meter 400 and read the second reading of the mass flow meter 400.

[0173] Step F3: close the pump 300 and the mass flow meter 400.

[0174] Steps F1, F2 and F3 can also be performed before step A1.

[0175] The flow resistance measurement system can further comprise a temperature detection mechanism 900 located in the inner cavity 110, and the distance between the temperature detection mechanism 900 and the bottom wall of the Dewar 100 is greater than or equal to the distance between the first port and the bottom wall of the Dewar 100. Optionally, the temperature detection mechanism 900 can be arranged on the inner wall of the Dewar 100, or on the portion of the communication pipeline located in the inner cavity 110.

[0176] In the process of introducing the liquid refrigerant into the inner cavity 110, if the temperature detected by the temperature detection mechanism 900 is less than or equal to the first preset temperature, the liquid storage tank 200 (i.e. the first on-off valve 210) and the first valve 710 are closed, and if the temperature detected by the temperature detection mechanism 900 is greater than or equal to the second preset temperature, the liquid storage tank 200 (i.e. the first on-off valve 210) and the first valve 710 are opened. The second preset temperature is greater than the first preset temperature.

[0177] It should be noted that the first preset temperature and the second preset temperature can be set according to the type of the liquid refrigerant. For example, in the case of liquid helium as the liquid refrigerant, the first preset temperature can be 4K, and the second preset temperature can be 5K.

[0178] After the pump 300, the mass flow meter 400 and the liquid storage tank 200 are closed, the measurement method can further comprise:

[0179] Step G1: opening the gas storage tank 500 and introducing the gaseous refrigerant into the capillary 1000 until the liquid refrigerant in the inner cavity 110 is vaporized.

[0180] During the step G1, the second valve 720 is also opened.

[0181] In the above scheme, the Dewar 100 is provided with an exhaust port, through which it can be observed whether the liquid refrigerant in the inner cavity 110 is completely vaporized. Alternatively, an observation window can be arranged on the bottom of the Dewar 100. The observation window can be a transparent structure, through which the inside of the inner cavity 110 can be observed to determine whether the liquid refrigerant is completely vaporized.

[0182] Step G2: closing the gas storage tank 500.

[0183] During the step G2, the second valve 720 is closed, and all the valves of the measurement system are closed.

[0184] In this case, the temperature of the liquid refrigerant is low, and the inner cavity 110 is closed after the liquid refrigerant in the inner cavity 110 is completely vaporized, so that the external air cannot enter the inner cavity 110 and the capillary 1000 and condense into ice, thereby preventing the capillary 1000 from being blocked.

[0185] After the capillary 1000 is measured in the liquid refrigerant temperature range by using the measurement method in the present application, the capillary 1000 can be applied to low-temperature working environments, gas-liquid two-phase working environments, and variable-pressure working environments.

[0186] It should be noted that the measurement system used by the measurement method for measuring the capillary flow resistance has the same structure as the measurement system described above.

[0187] Finally, it should be noted that the above examples are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that they can still modify the technical solutions recorded in the foregoing examples, or make equivalent replacements for some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A capillary flow resistance measurement system, characterized by, The measurement system comprises a dewar (100), a liquid storage tank (200), a pump (300), a mass flow meter (400) and a communication pipeline, wherein: The dewar (100) has an inner cavity (110), the liquid storage tank (200) is used for storing liquid refrigerant, the liquid storage tank (200) is in communication with the inner cavity (110), the communication pipeline is detachably connected with the dewar (100), a first port of the communication pipeline is located in the inner cavity (110), the first port is used for communicating with a capillary tube (1000), the pump (300) and the mass flow meter (400) are both arranged in the communication pipeline, and the pump (300) and the mass flow meter (400) are both located outside the dewar (100); The dewar (100) comprises an inner layer (120) and an outer layer (130), the outer layer (130) is arranged around the inner layer (120), and a sandwich layer is formed between the inner layer (120) and the outer layer (130), the sandwich layer is in communication with the communication pipeline through a vacuum extraction pipe (640) so that the sandwich layer is in communication with an inlet of the pump (300), and the vacuum extraction pipe (640) is provided with a fourth valve (740); The measurement system comprises a liquid delivery pipe (610), a first valve (710) and a first pressure detection mechanism (810), the liquid storage tank (200) and the inner cavity (110) are in communication through the liquid delivery pipe (610), and the first valve (710) and the first pressure detection mechanism (810) are arranged in the liquid delivery pipe (610).

2. The measurement system of claim 1, wherein, The measurement system further comprises a gas storage tank (500), the gas storage tank (500) is used for storing gaseous refrigerant, and the gas storage tank (500) is in communication with the communication pipeline; The dewar (100) is provided with an exhaust structure for exhausting gas in the inner cavity (110).

3. The measurement system of claim 2, wherein, The communication pipeline comprises a gas delivery pipe (620) and a communication pipe (630), the gas delivery pipe (620) is detachably connected with the dewar (100), one end of the gas delivery pipe (620) is located in the inner cavity (110), and a port located in the inner cavity (110) forms the first port, the other end of the gas delivery pipe (620) is in communication with the gas storage tank (500); The communication pipe (630) is in communication with the gas delivery pipe (620), and the communication position of the communication pipe (630) and the gas delivery pipe (620) is located outside the dewar (100), and the pump (300) and the mass flow meter (400) are arranged in the communication pipe (630).

4. The measurement system of claim 3, wherein, The gas delivery pipe (620) and the dewar (100) are plug-in connectable, so that the gas delivery pipe (620) is detachably connected with the dewar (100), and the first port is used for detachably connecting with the capillary tube (1000); The communication pipe (630) and the gas delivery pipe (620) are detachably connected.

5. The measurement system of claim 3, wherein, The measuring system further comprises a second valve (720) and a second pressure detection mechanism (820), both of which are arranged in the gas conveying pipe (620) and located between the communication position and the gas storage tank (500); The measuring system further comprises a third valve (730) and a third pressure detection mechanism (830), both of which are arranged in the communication pipe (630).

6. The measurement system of claim 5, wherein, The Dewar (100) further comprises a heat shield (140) arranged between the inner layer (120) and the outer layer (130) and surrounding the inner layer (120).

7. The measurement system of claim 1, wherein, The measuring system further comprises a temperature detection mechanism (900) located in the inner cavity (110), and the distance between the temperature detection mechanism (900) and the bottom wall of the Dewar (100) is greater than or equal to the distance between the first port and the bottom wall of the Dewar (100).

8. A method of measuring capillary flow resistance, characterized by, The measuring method is applied to the measuring system of claim 1, and the measuring method comprises: installing the capillary tube (1000) in the first port; placing the capillary tube (1000) in the inner cavity (110); opening the liquid storage tank (200) to introduce the liquid refrigerant medium into the inner cavity (110) so that the liquid refrigerant medium reaches a preset liquid level; opening the pump (300) and the mass flow meter (400) and reading the first reading of the mass flow meter (400); closing the pump (300), the mass flow meter (400) and the liquid storage tank (200).

9. The measurement method according to claim 8, characterized in that, The measuring system further comprises a gas storage tank (500) for storing gaseous refrigerant medium, the gas storage tank (500) being in communication with the communication pipeline, and the Dewar (100) being provided with an exhaust structure for exhausting gas in the inner cavity (110); After the capillary tube (1000) is placed in the inner cavity (110), before the liquid storage tank (200) is opened, the measuring method further comprises: opening the gas storage tank (500) to introduce gaseous refrigerant medium into the capillary tube (1000).

10. The measurement method according to claim 9, characterized by, After the capillary tube (1000) is installed in the first port, the measuring method further comprises: opening the gas storage tank (500); placing the outlet of the capillary tube (1000) in the intermediate liquid and observing whether the outlet of the capillary tube (1000) overflows gas bubbles, and if so, placing the capillary tube (1000) in the inner cavity (110).

11. The measurement method according to claim 9, characterized by, The communication pipeline comprises a gas delivery pipe (620) and a communication pipe (630), the gas delivery pipe (620) is detachably connected with the dewar (100), one end of the gas delivery pipe (620) is located in the inner cavity (110), and the port in the inner cavity (110) forms the first port, the other end of the gas delivery pipe (620) is in communication with the gas storage tank (500); The communication pipe (630) is in communication with the gas delivery pipe (620), and the communication position of the communication pipe (630) and the gas delivery pipe (620) is located outside the dewar (100), the pump (300) and the mass flow meter (400) are arranged on the communication pipe (630); Wherein, after the opening of the liquid storage tank (200), the liquid refrigerant medium is introduced into the inner cavity (110), and the liquid refrigerant medium reaches the preset liquid level, before the opening of the pump (300), the measurement method further comprises: Close the gas storage tank (500).

12. The method of measuring according to claim 11, wherein, The measurement system further comprises a second valve (720) and a second pressure detection mechanism (820), the second valve (720) and the second pressure detection mechanism (820) are both arranged on the gas delivery pipe (620), and both are located between the communication position and the gas storage tank (500); Wherein, in the process of opening the gas storage tank (500) and introducing the gaseous refrigerant medium into the capillary (1000), the opening degree of the second valve (720) is adjusted to control the pressure in the gas delivery pipe (620) within a second preset pressure range.

13. The method of claim 11, wherein, After reading the first reading of the mass flow meter (400), the measurement method further comprises: replacing the capillary (1000), Wherein, the replacement of the capillary (1000) comprises: Close the pump (300); Open the gas storage tank (500) to introduce the gaseous refrigerant medium into the capillary (1000); Take the capillary (1000) out of the inner cavity (110); Replace the capillary (1000) connected to the first port; Place the replaced capillary (1000) in the inner cavity (110).

14. The method of claim 11, wherein, After closing the pump (300), the mass flow meter (400) and the liquid storage tank (200), the measurement method further comprises: Open the gas storage tank (500) to introduce the gaseous refrigerant medium into the capillary (1000) until the liquid refrigerant medium in the inner cavity (110) is vaporized; Close the gas storage tank (500).

15. The method of claim 8, wherein, The dewar (100) comprises an inner layer (120) and an outer layer (130), the outer layer (130) is arranged around the inner layer (120), and a sandwich layer is formed between the inner layer (120) and the outer layer (130), the sandwich layer is in communication with the communication pipeline through a vacuum extraction pipe (640) to make the sandwich layer in communication with the inlet of the pump (300), and the vacuum extraction pipe (640) is provided with a fourth valve (740); Before the opening of the liquid storage tank (200), the measurement method further comprises: opening the fourth valve (740); opening the pump (300) until the interlayer is in a vacuum state; closing the pump (300) and the fourth valve (740).

16. The method of measuring according to claim 8, wherein, After the capillary (1000) is placed in the inner cavity (110), before the opening of the liquid storage tank (200), the measurement method further comprises: opening the pump (300) to extract the normal temperature gas in the inner cavity (110) through the capillary (1000); opening the mass flow meter (400) to read the second reading of the mass flow meter (400); closing the pump (300) and the mass flow meter (400).

17. The method of measuring of claim 8, wherein, The measurement system further comprises a temperature detection mechanism (900) located in the inner cavity (110), and the distance between the temperature detection mechanism (900) and the bottom wall of the Dewar (100) is greater than or equal to the distance between the first port and the bottom wall of the Dewar (100); wherein, during the process of introducing the liquid refrigerant medium into the inner cavity (110), if the temperature detected by the temperature detection mechanism (900) is less than or equal to a first preset temperature, the liquid storage tank (200) is closed, and if the temperature detected by the temperature detection mechanism (900) is greater than or equal to a second preset temperature, the liquid storage tank (200) is opened, the second preset temperature is greater than the first preset temperature, so that the liquid refrigerant medium reaches a preset liquid level.

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