Closed-cycle low-temperature control method and system

Abstract

The invention provides a closed-cycle low-temperature control method and system. The closed-cycle low-temperature control method comprises the steps that the current temperature and the current target flow of refrigeration gas currently conveyed into a conveying pipeline by a temperature control device are obtained; according to the current temperature, the first preset temperature and the current target flow, the output power of the first heating module is adjusted till the temperature of the refrigeration gas reaches the first preset temperature; in the process that the temperature of the refrigeration gas is controlled to be the first preset temperature, the output power of the first heating module is monitored; when it is monitored that the output power is higher than the power upper limit value, current target traffic is updated with a preset increment, and updated target traffic is obtained; and the output power adjusting step is repeated based on the updated target flow, so that the temperature of the refrigeration gas is controlled to be the first preset temperature. The refrigeration module is adopted to generate cold energy, the temperature of refrigeration gas is dynamically maintained by regulating and controlling the target flow and the output power of the first heating module, the automation degree is high, and the system operation stability is good.

Description

Technical Field

[0001] The present invention relates to the technical field of cryogenic control, and particularly to a closed-loop cryogenic control method and system. Background Art

[0002] In existing closed-loop liquefaction devices, it takes a long time to liquefy the refrigerating medium after startup, and the newly generated refrigerating liquid cannot be directly used for cooling external devices. Instead, it needs to be transferred to an additional storage device, resulting in cold loss during the transfer process. In addition, some closed-loop cryogenic devices directly cool the refrigerating medium through a temperature control device to form a refrigerating gas, and then directly transmit it to a continuous flow thermostat to achieve closed-loop cryogenic control. The cooling is relatively fast and there is no need for external storage. However, the cold generated by the refrigeration module in the temperature control device is uncontrollable, and many control parameters need to be adjusted during the entire regulation process to maintain the low-temperature environment of the device, and the multiple control parameters are highly dependent on each other. Summary of the Invention

[0003] In view of the problems existing in the above-mentioned prior art, the present invention provides a closed-loop cryogenic control method and system, which can dynamically maintain the temperature accuracy and temperature stability of the refrigerating gas delivered by the temperature control device, with high automation and accurate and reliable regulation. The technical solutions are as follows:

[0004] On the one hand, the present invention provides a closed-loop cryogenic control method, which is applied to a closed-loop cryogenic control system. The closed-loop cryogenic control system includes a temperature control device, a delivery pipeline, and a return pipeline. The gas outlet of the temperature control device, the delivery pipeline, the sample cold chamber, the return pipeline, and the gas inlet of the temperature control device are connected in sequence. The temperature control device includes a refrigeration module and a first heating module. The refrigeration module is used to cool the target gas passing through the temperature control device to form a refrigerating gas delivered to the delivery pipeline, and the first heating module is used to heat the refrigerating gas so that the refrigerating gas reaches a first preset temperature. The return pipeline is used to transport the target gas with increased temperature in the sample cold chamber back to the temperature control device. The method includes:

[0005] When the sample cold chamber is in the refrigeration mode, obtain the current temperature and the current target flow rate of the refrigerating gas currently delivered by the temperature control device to the delivery pipeline. The first preset temperature refers to the temperature target value of the refrigerating gas input by the temperature control device into the delivery pipeline, and the current target flow rate refers to the current flow rate setting value of the target gas in the return pipeline.

[0006] Adjust the output power of the first heating module according to the current temperature of the refrigerating gas in the delivery pipeline, the first preset temperature, and the current target flow rate until the temperature of the refrigerating gas in the delivery pipeline reaches the first preset temperature.

[0007] During the process of controlling the temperature of the refrigerating gas in the delivery pipeline to the first preset temperature, monitor the output power of the first heating module;

[0008] When it is monitored that the output power of the first heating module is higher than or equal to the power upper limit value, update the current target flow rate with a preset increment to obtain an updated target flow rate;

[0009] Repeat the above-mentioned output power adjustment step of the first heating module based on the updated target flow rate to control the temperature of the refrigerating gas in the delivery pipeline to the first preset temperature.

[0010] Further, after monitoring the output power of the first heating module during the process of controlling the temperature of the refrigerating gas in the delivery pipeline to the first preset temperature, the method further includes:

[0011] When it is monitored that the output power of the first heating module is lower than the power upper limit value, use the current target flow rate as the desired flow rate, control the return pipeline to return based on the current target flow rate, control the first heating module to operate at the current output power of the first heating module, and repeat the step of monitoring the output power of the first heating module.

[0012] Further, the closed-loop low-temperature control system further includes a second heating module, and the second heating module is used to heat the refrigerating gas input to the sample cold chamber so that the refrigerating gas reaches a second preset temperature; after using the current target flow rate as the desired flow rate, controlling the return pipeline to return based on the current target flow rate, and controlling the first heating module to operate at the current output power of the first heating module when it is monitored that the output power of the first heating module is lower than the power upper limit value, the method further includes:

[0013] Obtain the current temperature of the refrigerating gas input to the sample cold chamber;

[0014] Taking the second preset temperature as the target temperature of the refrigerating gas input to the sample cold chamber, adjust the output power of the second heating module according to the desired flow rate and the current temperature of the refrigerating gas input to the sample cold chamber until the temperature of the refrigerating gas input to the sample cold chamber reaches the second preset temperature, where the second preset temperature refers to the target value of the sample refrigeration temperature required for the refrigerating gas in the sample cold chamber to reach.

[0015] Further, before obtaining the current temperature of the refrigerating gas currently delivered by the temperature control device to the delivery pipeline, the first preset temperature, and the current target flow rate when the sample cold chamber is in the refrigeration mode, the method includes:

[0016] In response to the refrigeration mode trigger event of the sample cold chamber, control the refrigeration module to start, and control the flow rate setting value of the target gas in the return pipeline to be a preset pre-cooling flow rate;

[0017] In the state of returning the target gas based on the preset pre-cooling flow rate, with the first preset temperature as the target temperature, adjust the output power of the first heating module according to the temperature of the refrigerating gas in the delivery pipeline and the preset pre-cooling flow rate until the output power of the first heating module reaches the power output steady-state condition;

[0018] Determine the output power that meets the output steady-state condition as the target pre-cooling power, and control the first heating module to operate at the target pre-cooling power;

[0019] Increment the flow rate setting value in the return pipeline from the preset pre-cooling flow rate to the target flow rate.

[0020] Further, the closed-loop low-temperature control system includes a flow control module. The flow control module includes a first connection valve, a second connection valve, a bleed valve, and a circulation pump. The first connection valve is arranged in the gas inlet pipeline of the temperature control device; the gas outlet of the sample cold chamber, the circulation pump, the second connection valve, and the gas inlet of the temperature control device are sequentially connected by pipelines to form the return pipeline. The bleed valve is arranged between the second connection valve and the circulation pump, with one end connected to the return pipeline and the other end connected to the outside; before controlling the refrigeration module to start, the method further includes:

[0021] In response to the refrigeration mode trigger event of the sample cold chamber, control the first connection valve to open to deliver the target gas to the temperature control device;

[0022] When it is detected that the target gas is flowing in the return pipeline, control the circulation pump and the bleed valve to open, and control the second connection valve to close for pipeline cleaning;

[0023] When it is detected that the cleaning duration reaches the preset cleaning duration, control the bleed valve to close and the second connection valve to open, and control the flow rate setting value of the target gas in the return pipeline to be the preset cleaning flow rate to trigger the refrigeration module to start.

[0024] Further, the flow control module further includes a pressure reducing valve disposed in the gas inlet pipeline; before controlling the circulation pump and the air release valve to open and controlling the second communication valve to close for pipeline cleaning in a state where it is detected that the target gas is flowing in the return pipeline, the method further includes:

[0025] Controlling the pressure reducing valve to open;

[0026] Monitoring the current pressure in the gas inlet pipeline;

[0027] Adjusting the opening degree of the pressure reducing valve according to the difference between the current pressure in the gas inlet pipeline and the preset pressure until the pressure in the gas inlet pipeline reaches the preset pressure.

[0028] Further, the temperature control device is provided with a refrigeration inner cavity for accommodating the target gas and a refrigeration outer cavity covering the refrigeration inner cavity, the sample cold cavity is provided with a sample inner cavity for placing a sample and a sample outer cavity covering the sample inner cavity, the closed-cycle low-temperature control system includes a vacuum control module, and the vacuum control module includes a first vacuum valve, a second vacuum valve and a vacuum pump. The vacuum pump is communicably connected to the refrigeration outer cavity through the first vacuum valve and communicably connected to the sample outer cavity through the second vacuum valve; before controlling the refrigeration module to start, the method further includes:

[0029] In response to a refrigeration mode triggering event of the sample cold cavity, controlling the first vacuum valve, the second vacuum valve and the vacuum pump to open to evacuate the refrigeration outer cavity and the sample outer cavity respectively until the refrigeration outer cavity and the sample outer cavity meet the vacuum conditions.

[0030] Further, the method further includes:

[0031] In response to a heating mode triggering event of the sample cold cavity, if the first vacuum valve, the second vacuum valve and the vacuum pump are in an open state, controlling the first vacuum valve, the second vacuum valve and the vacuum pump to close;

[0032] In response to a switching event from the heating mode to the refrigeration mode, if the first vacuum valve is in a closed state and the refrigeration outer cavity is in a vacuum state, controlling the second vacuum valve and the vacuum pump to open.

[0033] Further, after controlling the return pipeline to return based on the current target flow rate and controlling the first heating module to operate at the current output power of the first heating module, and repeating the step of monitoring the output power of the first heating module, the method further includes:

[0034] In response to a heating mode triggering event, adjust the flow rate set value of the target gas in the reflux pipeline to a preset heating flow rate, and control the refrigeration module to turn off;

[0035] Taking the third preset temperature as the target temperature of the refrigerating gas in the delivery pipeline, adjust the heating power of the first heating module according to the preset heating flow rate and the current temperature of the refrigerating gas in the delivery pipeline until the temperature of the refrigerating gas in the delivery pipeline reaches the third preset temperature;

[0036] Taking the fourth preset temperature as the target temperature of the refrigerating gas input to the sample cold chamber, adjust the heating power of the second heating module according to the preset heating flow rate and the current temperature of the refrigerating gas input to the sample cold chamber until the temperature of the refrigerating gas in the sample cold chamber reaches the fourth preset temperature;

[0037] Control the first heating module, the second heating module and the vacuum control module to turn off.

[0038] On the other hand, the present invention provides a closed-loop low-temperature control system. The closed-loop low-temperature control system includes a temperature control device, a delivery pipeline, a reflux pipeline and a control device. The gas outlet of the temperature control device, the delivery pipeline, the sample cold chamber, the reflux pipeline and the gas inlet of the temperature control device are connected in sequence. The temperature control device includes a refrigeration module and a first heating module. The refrigeration module is used to cool the target gas passing through the temperature control device to form a refrigerating gas delivered to the delivery pipeline. The first heating module is used to heat the refrigerating gas so that the refrigerating gas reaches a first preset temperature; the reflux pipeline is used to transport the target gas heated up in the sample cold chamber back to the temperature control device; the control device includes:

[0039] An acquisition module, configured to acquire the current temperature and the current target flow rate of the refrigerating gas currently delivered by the temperature control device to the delivery pipeline when the sample cold chamber is in the refrigeration mode. The first preset temperature refers to the temperature target value of the refrigerating gas input by the temperature control device to the delivery pipeline, and the current target flow rate refers to the current flow rate set value of the target gas in the reflux pipeline;

[0040] A power adjustment module, configured to adjust the output power of the first heating module according to the current temperature of the refrigerating gas in the delivery pipeline, the first preset temperature and the current target flow rate until the temperature of the refrigerating gas in the delivery pipeline reaches the first preset temperature;

[0041] A monitoring module, configured to monitor the output power of the first heating module during the process of controlling the temperature of the refrigerating gas in the delivery pipeline to be the first preset temperature;

[0042] An update module, configured to update the current target flow rate with a preset increment to obtain an updated target flow rate when it is detected that the output power of the first heating module is higher than or equal to the power upper limit value;

[0043] A circulation module, configured to repeat the above-mentioned output power adjustment step of the first heating module based on the updated target flow rate to control the temperature of the refrigerating gas in the delivery pipeline to the first preset temperature.

[0044] On the other hand, the present invention provides a storage medium, in which at least one instruction or at least one program segment is stored, and the at least one instruction or the at least one program segment is loaded and executed by a processor to implement the closed-loop low-temperature control method as described above.

[0045] Implementing the present invention has the following beneficial effects:

[0046] The present invention uses a refrigeration module to generate cold, and regulates the temperature of the temperature control device by regulating the target flow rate of the target gas flowing back to the temperature control device and the output power of the first heating module, and neutralizes the heat generated by the heating power of the first heating module and the heat carried by the target flow rate of the target gas delivered to the temperature control device with the cold generated by the refrigeration module, dynamically maintaining the refrigerating gas delivered from the temperature control device to the delivery pipeline to reach the first preset temperature, delivering the refrigerating gas to the sample cold chamber and effectively cooling the sample in the sample cold chamber, with good temperature accuracy and temperature stability; in the case of uncontrollable multi-variables in the closed-loop low-temperature control system, this closed-loop low-temperature control method enables the temperature control device to achieve a controllable and stable output of cold, with a high degree of automation, fast regulation of the target flow rate and the output power of the first heating module, good timeliness and high accuracy, which is beneficial to maintaining the temperature stability and operation stability of the entire closed-loop low-temperature control system. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the present invention, and those of ordinary skill in the art can obtain other drawings according to these drawings without creative efforts.

[0048] Figure 1 It is a schematic structural diagram of the hardware device in the closed-loop low-temperature control system in a possible implementation manner of the present invention;

[0049] Figure 2 For Figure 1 a partial enlarged structural view of the delivery pipeline in

[0050] Figure 3The logical structure diagram of a closed-loop low-temperature control method provided by an embodiment of the present invention;

[0051] Figure 4 The logical structure diagram of another closed-loop low-temperature control method provided by an embodiment of the present invention;

[0052] Figure 5 The logical structure diagram of the temperature control method of the refrigerating gas in the sample cold cavity in a possible implementation manner provided by an embodiment of the present invention;

[0053] Figure 6 The logical structure diagram of the pre-cooling method of a closed-loop low-temperature control system provided by an embodiment of the present invention;

[0054] Figure 7 The logical structure diagram of the pipeline cleaning method of a closed-loop low-temperature control system provided by an embodiment of the present invention;

[0055] Figure 8 The logical structure diagram of the pre-vacuum method of a closed-loop low-temperature control system provided by an embodiment of the present invention;

[0056] Figure 9 The logical structure diagram of the heating method of a closed-loop low-temperature control system provided by an embodiment of the present invention;

[0057] Figure 10 One of the flowcharts of the closed-loop low-temperature control method in a specific embodiment of the present invention;

[0058] Figure 11 Two of the flowcharts of the closed-loop low-temperature control method in a specific embodiment of the present invention.

[0059] Among them, the reference numerals correspond to:

[0060] 1 - temperature control device, 11 - refrigeration module, 2 - delivery pipeline, 3 - sample cold cavity, 4 - return pipeline, 5 - flow control module, 51 - first connection valve, 52 - flow monitoring element, 53 - circulation pump, 54 - air release valve, 55 - second connection valve, 56 - buffer unit, 57 - pressure reducing valve, 58 - pressure monitoring element, 6 - target gas storage module, 7 - gas inlet pipeline, 8 - vacuum control module, 81 - first vacuum valve, 82 - second vacuum valve, 83 - vacuum pump, 9 - sample cold support. Specific embodiments

[0061] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Therefore, it should not be construed as a limitation of the present invention. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0062] It should be noted that the terms "first", "second", etc. in the specification, claims and drawings of the present invention are used to distinguish similar objects, and do not necessarily have to be used to describe a specific order or sequence. It should be understood that such data can be interchanged under appropriate circumstances so that the embodiments of the present invention can be implemented in an order other than the following illustrations or the following description. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusion. For example, a process, method, system, product or server including a series of steps or units does not necessarily have to be limited to those steps or units clearly listed, but may include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0063] In view of the problem in the prior art that the cooling capacity provided by the refrigeration module in the closed-loop low-temperature system is uncontrollable, and in order to maintain the temperature stability of the refrigeration gas output by the temperature control device, it is necessary to regulate multiple control parameters in the system, but there is a high degree of dependence between the multiple control parameters. The embodiments of the present invention provide a closed-loop low-temperature control method and system. The closed-loop low-temperature control method can be applied to the control device of the closed-loop low-temperature control system provided by the embodiments of the present invention and is regulated by the control device. When a refrigeration demand occurs and the sample cold chamber is in the refrigeration mode, the control device obtains the current temperature and the current target flow rate of the refrigeration gas currently delivered by the temperature control device to the delivery pipeline; adjusts the output power of the first heating module according to the current temperature of the refrigeration gas in the delivery pipeline, the first preset temperature, and the current target flow rate until the temperature of the refrigeration gas in the delivery pipeline reaches the first preset temperature; during the process of controlling the temperature of the refrigeration gas in the delivery pipeline to be the first preset temperature, monitor the output power of the first heating module; in the case where it is monitored that the output power of the first heating module is higher than or equal to the power upper limit value, update the current target flow rate with a preset increment to obtain an updated target flow rate; repeat the above step of adjusting the output power of the first heating module based on the updated target flow rate to control the temperature of the refrigeration gas in the delivery pipeline to be the first preset temperature. It has a high degree of automation, fast and accurate regulation, is beneficial to maintaining the temperature stability of the entire closed-loop low-temperature control system, and improves the temperature control performance of the closed-loop low-temperature control system.

[0064] Specifically, as Figure 1As shown in the figure, a closed-loop low-temperature control system provided in this embodiment includes a temperature control device 1, a delivery pipeline 2, a return pipeline 4, and a control device. The gas outlet of the temperature control device 1, the delivery pipeline 2, the sample cold chamber 3, the return pipeline 4, and the gas inlet of the temperature control device 1 are connected in sequence, so that the target gas and the refrigerating gas formed after the target gas is cooled can circulate in the pipeline, avoiding the refrigerating time on one side of the sample cold chamber 3 being limited by the consumption of the target gas, being able to greatly extend the refrigerating time of the sample cold chamber 3 while saving the consumption of the target gas, and effectively improving the temperature control performance of the closed-loop low-temperature control system; wherein, the target gas and the refrigerating gas are the same gas with different temperatures, and can be selected as helium and nitrogen, with good refrigeration effect.

[0065] As Figure 1 shown in the figure, the temperature control device 1 includes a refrigeration module 11 and a first heating module. Among them, the refrigeration module 11 can provide cold energy to cool the target gas passing through the temperature control device 1 to form a refrigerating gas delivered to the delivery pipeline 2, and the first heating module is used to heat the refrigerating gas so that the refrigerating gas reaches the first preset temperature; that is, the target gas enters the temperature control device 1 and is first cooled by the refrigeration module 11 to form a refrigerating gas. At this time, the temperature of the refrigerating gas is lower than the first preset temperature, and then the first heating module heats the refrigerating gas so that the temperature of the refrigerating gas rises to the first preset temperature. Then, the refrigerating gas output from the gas outlet of the temperature control device 1 is the refrigerating gas at the first preset temperature; the refrigerating gas at the first preset temperature is delivered from the temperature control device 1 to the delivery pipeline 2 and then to the sample cold chamber 3, thereby cooling the sample cold chamber 3; in the sample cold chamber 3, the refrigerating gas will heat up after heat exchange to form a heated target gas, and the return pipeline 4 is used to deliver the heated target gas in the sample cold chamber 3 back to the temperature control device 1 for circulating cooling, and form a refrigerating gas again to refrigerate the sample cold chamber 3.

[0066] Specifically, the closed-loop low-temperature control system further includes a second heating module, which is used to heat the refrigerating gas input to the sample cold chamber 3 so that the refrigerating gas reaches the second preset temperature, further improving the accuracy and stability of the refrigerating temperature of the refrigerating gas in the sample cold chamber 3.

[0067] Specifically, in an optional embodiment, the closed-loop low-temperature control system further includes a third heating module, which is used to heat the refrigerating gas of the sample cold holder 9 so that the refrigerating gas reaches the cold holder preset temperature, so as to ensure that the temperatures of different target areas in the sample cold chamber 3 can be maintained relatively evenly at the second preset temperature. Especially for a sample cold chamber 3 with a certain length, controlling the temperature of the sample cold holder 9 can further improve the accuracy of temperature control in different areas of the sample cold chamber 3.

[0068] Specifically, the closed-loop low-temperature control system includes a flow control module 5, which is used to control the on-off of each pipeline in the closed-loop low-temperature control system. Specifically, it can be used to clean the pipelines in the closed-loop low-temperature control system before the refrigeration module 11 starts to execute the cooling step, and can also be used to isolate the pipelines in the closed-loop low-temperature control system from the outside world and form a closed-loop pipeline during the cooling step executed by the temperature control device 1.

[0069] Specifically, the flow control module 5 includes a first communication valve 51, a second communication valve 55, a pressure reducing valve 57, a gas release valve 54, and a circulation pump 53. The first communication valve 51 is arranged in the gas inlet pipeline 7 of the temperature control device 1 to control the on-off of the gas inlet pipeline 7. Among them, the gas inlet pipeline 7 is respectively communicated with the target gas storage module 6 and the gas inlet of the temperature control device 1 to transport the target gas. The pressure reducing valve 57 is arranged in the gas inlet pipeline 7 to reduce the pressure of the target gas input into the gas inlet pipeline 7, reduce the pressure load of the gas inlet pipeline 7, and maintain the gas inlet pipeline 7 under safe and stable operating conditions. The gas outlet of the sample cold chamber 3, the circulation pump 53, the second communication valve 55, and the gas inlet of the temperature control device 1 are sequentially connected by pipelines to form a return pipeline 4. The gas release valve 54 is arranged between the second communication valve 55 and the circulation pump 53, with one end communicated with the return pipeline 4 and the other end communicated with the outside world. A buffer unit 56 is also arranged in the return pipeline 4, and the buffer unit 56 is communicated between the gas inlet pipeline 7 and the circulation pipeline.

[0070] Specifically, as Figure 2 shown, between the gas outlet of the temperature control device 1 and the gas inlet of the sample cold chamber 3, a section of the return pipeline 4 of the conveying pipeline 2 and the outlet end of the sample cold chamber 3 is of an inner and outer nested structure. Among them, the conveying pipeline 2 is coaxially arranged inside this section of the return pipeline 4, and this section of the return pipeline 4 is an annular pipeline covering the outside of the conveying pipeline 2, that is, the inner wall of this section of the return pipeline 4 is reused as the outer wall of the conveying pipeline 2, which can isolate the outer wall of the conveying pipeline 2 from the outside atmosphere to a certain extent, further reduce the cold loss during the transportation of the refrigeration gas in the conveying pipeline 2, improve the refrigeration power of the refrigeration gas transported to the sample cold chamber 3, and reduce energy waste.

[0071] Specifically, the temperature control device 1 is provided with a refrigeration inner cavity for accommodating the target gas and a refrigeration outer cavity covering the refrigeration inner cavity. The sample cold cavity 3 is provided with a sample inner cavity for placing the sample and a sample outer cavity covering the sample inner cavity. The closed-loop cryogenic control system includes a vacuum control module 8. The vacuum control module 8 includes a first vacuum valve 81, a second vacuum valve 82, and a vacuum pump 83. The vacuum pump 83 is communicably connected to the refrigeration outer cavity through the first vacuum valve 81 and communicably connected to the sample outer cavity through the second vacuum valve 82, so as to control a vacuum environment to be formed between the refrigeration inner cavity and the sample inner cavity and the outside atmosphere respectively, playing a heat insulation role, further reducing the heat exchange between the refrigeration inner cavity and the sample inner cavity and the outside atmosphere, being beneficial to maintaining the temperature stability in the refrigeration inner cavity and the sample inner cavity, and saving energy.

[0072] Specifically, a plurality of monitoring elements are provided in the closed-loop cryogenic control system. The plurality of monitoring elements include a temperature monitoring element, a pressure monitoring element 58, and a flow monitoring element 52, so as to display the state of the closed-loop cryogenic control system at the current moment for the monitoring personnel to refer to and understand the operating state of the current closed-loop cryogenic control system. For example, the temperature control device 1 is provided with at least two temperature monitoring elements. The at least two temperature monitoring elements are respectively located in different regions of the temperature control device 1. Optionally, one of the temperature monitoring elements is provided at the first heating module to monitor the temperature of the refrigerating gas at the first heating module.

[0073] In addition, it should be noted that some monitoring elements in the closed-loop cryogenic control system are affected by the pressure in the pipeline, and there is a deviation between the display reading of the monitoring element under different pressures and the actual value in the current system. For example, the temperature monitoring element displays the current temperature reading, but this temperature reading is the temperature monitored by the temperature monitoring element under the calibration pressure. When the pressure in the pipeline is different from the calibration pressure, the actual current temperature in the pipeline under the non-calibration pressure is different from the current temperature reading. The closed-loop cryogenic control method is to adjust the set values of multiple control parameters in the system so that the control parameters in the system are adjusted more accurately and reliably, improving the stability of the system operation.

[0074] The closed-loop cryogenic control method of the embodiment of the present invention will be introduced in detail below. Refer to the attached Figure 3 , the method includes:

[0075] S101, when the sample cold cavity is in the refrigeration mode, obtain the current temperature and the current target flow rate of the refrigerating gas currently delivered by the temperature control device to the delivery pipeline.

[0076] Among them, the sample cold chamber being in the refrigeration mode means the state where the refrigeration module in the temperature control device has been started, the refrigeration gas has been transported in the transport pipeline for a certain period of time, and the target gas after temperature rise has been refluxed in the reflux pipeline for a certain period of time. At this time, the gas outlet of the temperature control device, the transport pipeline, and the sample cold chamber in the closed-loop low-temperature control system have been pre-conditioned to a relatively low-temperature environment.

[0077] The first preset temperature refers to the temperature target value of the refrigeration gas input by the temperature control device into the transport pipeline, that is, the temperature set value that the refrigeration gas needs to reach; this first preset temperature can be set according to actual situations. This first preset temperature can be a specific value. For example, the first preset temperature can be 4.5K, or it can be a numerical range. For example, the first preset temperature can be 4.2 - 4.9K. The present invention does not make specific limitations in this regard.

[0078] Optionally, the first preset temperature can be pre-configured by the control device or obtained by the control device. For example, when an operator inputs the first preset temperature through the input panel of the control device, the control device obtains the first preset temperature input in the input panel and executes subsequent regulation steps. At this time, the first preset temperature can be adjusted to meet various different temperature control scenarios and temperature control requirements, with a wide range of applications.

[0079] The current target flow rate refers to the current flow rate set value of the target gas in the reflux pipeline. This current target flow rate can be dynamically updated as the regulation process progresses, that is, the flow rate set value is adjustable. This current target flow rate can be a specific value. For example, the current target flow rate can be 6L / min, or it can be a numerical range. For example, the current target flow rate can be 11.5 - 12L / min. The present invention does not make specific limitations in this regard.

[0080] In an alternative embodiment, a flow control element is provided in the reflux pipeline. By adjusting the maximum flow rate set value of the flow control element through the control device, the maximum flow rate of the target gas flowing through the flow control element can be restricted, so that the flow rate of the target gas is maintained within the maximum flow rate set value range. Then, the current target flow rate is the maximum flow rate set value currently set by the flow control element. By regulation, the flow rate of the target gas in the reflux pipeline is made to reach and dynamically maintained within this maximum flow rate set value range, which is convenient and accurate for regulation; in addition, this flow control element can also serve as a flow monitoring element, sending the currently set current target flow rate of itself to the control device, so that the control device can quickly and accurately obtain the current target flow rate in the current reflux pipeline, facilitating the continuation of subsequent steps such as S103, with fast response and timely and accurate control.

[0081] S103. Adjust the output power of the first heating module according to the current temperature of the refrigerating gas in the conveying pipeline, the first preset temperature, and the current target flow rate until the temperature of the refrigerating gas in the conveying pipeline reaches the first preset temperature.

[0082] When the sample cold chamber is in the refrigeration mode, the refrigeration module has been started and continuously outputs cold. However, the cold output by the refrigeration module also varies. For example, when the flow rate of the target gas flowing through the refrigeration module changes, the cold output by the refrigeration module will also change, resulting in an uncontrollable temperature of the refrigerating gas after passing through the refrigeration module. In this embodiment, the refrigeration power of the refrigeration module is relatively large, so that the refrigerating gas with different flow rates passing through the refrigeration module can be reduced to a temperature lower than the first preset temperature. Then, by adjusting the output power of the first heating module, the refrigerating gas under the current target flow rate is heated to dynamically control the refrigerating gas output from the gas outlet of the temperature control device after passing through the first heating module to reach the first preset temperature, realizing controllable and effective regulation of the temperature of the refrigerating gas. The regulation is fast and accurate, and the regulation reliability is good, and it can effectively maintain the stability of the temperature of the refrigerating gas.

[0083] It should be noted that the temperature of the refrigerating gas after being cooled by the refrigeration module is lower than the first preset temperature, and the output power of the first heating module is greater than 0, that is, the output power output by the first heating module is always used for heating, so that the temperature of the refrigerating gas in the temperature control device can be effectively controlled. Otherwise, if the output power of the first heating module is equal to 0, it means that the first heating module does not work or is used for cooling. In the case where the refrigeration module cannot accurately and effectively control the temperature of the refrigerating gas, the control of the temperature of the refrigerating gas by the entire temperature control device will also get out of control.

[0084] S105. During the process of controlling the temperature of the refrigerating gas in the conveying pipeline to be the first preset temperature, monitor the output power of the first heating module.

[0085] In some embodiments, the output power of the first heating module detected in this step is the instantaneous power; in other embodiments, the output power of the first heating module detected in this step is the average power within a preset time interval, and it is determined that the output power of the first heating module reaches a stable state under the condition of the first preset temperature. Among them, the preset time interval is 2 min to 3 min. It can be understood that the preset time interval can be any point value between 2 min and 3 min. Exemplarily, the preset time interval can be 2 min, 2.5 min, 3 min, etc., which can not only reserve enough time for the closed-loop low-temperature control system to reach a stable state, but also avoid prolonging the cooling time and improve the cooling efficiency.

[0086] S107. When it is detected that the output power of the first heating module is higher than or equal to the power upper limit value, update the current target flow rate with a preset increment to obtain an updated target flow rate.

[0087] When the temperature of the refrigerating gas is the first preset temperature, the greater the flow rate of the refrigerating gas in the delivery pipeline, the greater the refrigerating power of the refrigerating gas delivered to the sample cold chamber; and the heat provided by the current target flow rate (the heat carried by the target gas after heating up) and the heat provided by the output power of the first heating module jointly neutralize the uncontrollable cold quantity output by the refrigerating module. When the current target flow rate increases, it means that the target gas after heating up flowing back to the temperature control device increases, and the required output power of the first heating module decreases. On the contrary, when the current target flow rate decreases, it means that the target gas after heating up flowing back to the temperature control device decreases, and the required output power of the first heating module increases, so as to effectively maintain the temperature stability of the refrigerating gas delivered by the temperature control device to the delivery pipeline.

[0088] In some embodiments, in order to maximize the refrigerating power output to the sample cold chamber, the current target flow rate is updated so that when the temperature of the refrigerating gas is the first preset temperature, the updated target flow rate reaches the maximum value, and correspondingly, the output power of the first heating module reaches the minimum value.

[0089] In this embodiment, the power upper limit value refers to the output power threshold that is lower when the refrigerating power output to the sample cold chamber reaches the maximum (or the current target flow rate reaches the maximum flow rate setting value) when the temperature of the refrigerating gas in the delivery pipeline is the first preset temperature; when the output power of the first heating module is higher than or equal to this power upper limit value, it indicates that the refrigerating power output to the sample cold chamber has not reached the maximum at this time, so the current target flow rate is updated with a preset increment to obtain an updated target flow rate, and this updated target flow rate is greater than the current target flow rate, so as to further reduce the output power of the first heating module.

[0090] This power upper limit value can be set in advance. This power upper limit value can be a specific value. For example, the power upper limit value can be 0.5W, or it can be a numerical range. For example, the power upper limit value can be 0.45 - 0.55W. The present invention does not make specific limitations on this.

[0091] The preset increment is the set value of the flow rate variable of the target gas in the return pipeline increased each time the current target flow rate is updated. The sum of the preset increment and the current target flow rate is equal to the updated target flow rate. The preset increment can be set in advance. The preset increment can be a specific value. For example, the preset increment can be 0.3 L / min, or it can be a numerical range. For example, the preset increment can be 0.3 - 0.5 L / min. The present invention does not make specific limitations on this. Moreover, during the process of repeating the update step multiple times, the preset increment in the previous update step can be the same as that in the subsequent update step, or different from that in the subsequent update step, with good regulation flexibility.

[0092] In some embodiments, after the control device obtains the updated target flow rate, the control device can also send the updated target flow rate to the flow control element to update the current maximum flow rate set value in the flow control element, so that the heated target gas in the return pipeline flows back according to the updated target flow rate, with fast response and timely and accurate control.

[0093] S109, repeat the output power adjustment step of the first heating module based on the updated target flow rate to control the temperature of the refrigerating gas in the conveying pipeline to the first preset temperature.

[0094] If the set value of the flow rate of the target gas in the return pipeline is directly increased to a relatively large target flow rate in the refrigeration mode, at this time, the temperature of the target gas itself is relatively high, the load of the refrigeration module is too heavy, and for a large amount of target gas, the refrigeration module needs to provide a greater refrigeration power and a longer refrigeration time to reduce the temperature of the target gas to the first preset temperature. In this step, repeat the output power adjustment step of the first heating module, that is, repeat the above steps S103 - S107, and gradually increase the updated target flow rate through multiple step-by-step updates with a preset increment. The refrigeration module can cool the target gas at a smaller target flow rate faster, and the temperature of the heated target gas in the return pipeline is lower than that of the target gas directly input into the refrigeration module in a large amount. To a certain extent, the returned target gas can cooperate with the refrigeration module to cool the target gas of this part of the preset increment increased in this update step, reducing the load of the refrigeration module. After repeating the update step multiple times, it is possible to gradually cool the increased target gas, accelerate the overall refrigeration efficiency of the refrigeration module, save the energy consumption of the refrigeration module, and make the temperature of the refrigerating gas in the conveying pipeline more easily reach the first preset temperature quickly.

[0095] In some other embodiments, during the actual operation of the closed-loop cryogenic control system, as time changes, the control parameters in the closed-loop cryogenic control system will change, resulting in a change in the temperature of the refrigerating gas delivered to the delivery pipeline. Therefore, during the entire operation process, it is also necessary to monitor the output power of the first heating module, dynamically update the current target flow rate, and dynamically adjust the output power of the first heating module so that the temperature of the refrigerating gas delivered to the delivery pipeline is the first preset temperature, maintaining the dynamic stability of the temperature.

[0096] Specifically, as Figure 4 shown, after monitoring the output power of the first heating module during the process of controlling the temperature of the refrigerating gas in the delivery pipeline to be the first preset temperature, that is, after step S105, the method further includes:

[0097] S111. When it is monitored that the output power of the first heating module is lower than the power upper limit value, use the current target flow rate as the desired flow rate, control the return pipeline to return based on the current target flow rate, and control the first heating module to operate at the current output power of the first heating module, and repeat the step of monitoring the output power of the first heating module.

[0098] The desired flow rate refers to the maximum flow rate setting value of the target gas after temperature rise in the return pipeline when the temperature of the refrigerating gas in the delivery pipeline is the first preset temperature; at this time, the output power of the first heating module is lower than the power upper limit value, and the refrigerating power delivered to the sample cold chamber reaches the maximum; then, using this desired flow rate and the current output power of the first heating module as the steady-state operation of the closed-loop cryogenic control system, the cold loss in the delivery pipeline is extremely small, and it can effectively control the temperature of the refrigerating gas reaching the sample cold chamber to be the first preset temperature, greatly improving the refrigeration efficiency.

[0099] In some preferred embodiments, this step S111 is executed after step S109, that is, when the output power adjustment step of the first heating module is repeated multiple times, the output power of the first heating module is gradually adjusted to a state lower than the power upper limit value. Correspondingly, after multiple updates of the preset increment, the updated target flow rate reaches the maximum target flow rate that can be achieved when the temperature of the refrigerating gas in the delivery pipeline is the first preset temperature, that is, the desired flow rate. And when the temperature of the refrigerating gas in the delivery pipeline is the same, the greater the target flow rate, the greater the cold quantity carried by the refrigerating gas. Therefore, under the condition of the desired flow rate, the sample cold chamber can be better cooled and the temperature can be maintained, and the stability and reliability of temperature control are good.

[0100] The entire control method can efficiently cool the temperature of the refrigerating gas currently delivered by the temperature control device to the first preset temperature in the closed-loop low-temperature control system, and can quickly make the flow rate of the refrigerating gas delivered to the sample cold chamber reach the desired flow rate. The cooling efficiency is high, and under the conditions of the desired flow rate and the first preset temperature, the heat loss of the refrigerating gas in the delivery pipeline is reduced, so that the refrigerating power delivered to the sample cold chamber reaches the maximum, and the temperature of the refrigerating gas in the sample cold chamber can be efficiently and accurately controlled.

[0101] Specifically, as Figure 5 shown, when it is monitored that the output power of the first heating module is lower than the power upper limit value, taking the current target flow rate as the desired flow rate, and after controlling the return pipeline to return based on the current target flow rate and controlling the first heating module to operate at the current output power of the first heating module, that is, after step S111, the method further includes:

[0102] S202, obtaining the current temperature of the refrigerating gas input to the sample cold chamber.

[0103] S204, taking the second preset temperature as the target temperature of the refrigerating gas input to the sample cold chamber, and adjusting the output power of the second heating module according to the desired flow rate and the current temperature of the refrigerating gas input to the sample cold chamber until the temperature of the refrigerating gas input to the sample cold chamber reaches the second preset temperature. The second preset temperature refers to the target value of the sample refrigeration temperature required for the refrigerating gas in the sample cold chamber.

[0104] Among them, the second preset temperature is greater than the first preset temperature, so that the temperature of the refrigerating gas input by the temperature control device to the sample cold chamber is lower than the second preset temperature, thereby reserving a regulation space for the refrigerating gas delivered to the sample cold chamber to avoid temperature out of control; in this embodiment, the output power of the second heating module is also greater than 0, so that the second heating module can always output heat and stably and reliably adjust the temperature of the refrigerating gas in the sample cold chamber.

[0105] Moreover, during the process of transporting the refrigerating gas to the sample cold chamber through the delivery pipeline, the current flow rate set value of the target gas in the return pipeline is updated to the desired flow rate to minimize the loss of cold in the delivery pipeline as much as possible. However, the refrigerating gas reaching the sample cold chamber may still experience a slight temperature rise, resulting in a deviation between the current temperature of the refrigerating gas input to the sample cold chamber and the first preset temperature. Also, the temperatures of the refrigerating gas reaching the sample cold chamber at different times may vary. By adjusting the output power of the second heating module to heat the refrigerating gas input to the sample cold chamber, fine-tuning of the temperature of the refrigerating gas in the sample cold chamber can be achieved, enabling the temperature of the refrigerating gas input to the sample cold chamber to reach the second preset temperature, further enhancing the accuracy and stability of temperature control in the sample cold chamber.

[0106] In some embodiments, the sample cold chamber is provided with a temperature monitoring element. The current temperature of the refrigerating gas input to the sample cold chamber is obtained through this temperature monitoring element and sent to the control device by the temperature monitoring element, so that the control device can further regulate the temperature in the sample cold chamber, which is convenient, fast, and timely and accurate in regulation.

[0107] Specifically, in an alternative embodiment, in the case where it is monitored that the output power of the first heating module is lower than the power upper limit value, taking the current target flow rate as the desired flow rate, and after controlling the return pipeline to return based on the current target flow rate and controlling the first heating module to operate at the current output power of the first heating module, that is, after step S111, the method further includes:

[0108] Obtain the current temperature of the refrigerating gas input to the sample cold stage.

[0109] Taking the cold stage preset temperature as the target temperature of the refrigerating gas input to the sample cold stage, and adjusting the output power of the third heating module according to the desired flow rate and the current temperature of the refrigerating gas input to the sample cold stage until the temperature of the refrigerating gas input to the sample cold stage reaches the cold stage preset temperature. The cold stage preset temperature refers to the target value of the sample refrigeration temperature required for the refrigerating gas in the sample cold stage.

[0110] Specifically, the above steps S101 - S111 and steps S202 - S204 are all carried out when the sample cold chamber is in the refrigeration mode, that is, the steps of formal refrigeration. Before formal refrigeration, the closed-loop low-temperature control system is pre-cooled first to further improve the cooling efficiency. Then, as Figure 6 shown, before obtaining the current temperature of the refrigerating gas currently transported to the delivery pipeline by the temperature control device, the first preset temperature, and the current target flow rate when the sample cold chamber is in the refrigeration mode, that is, before step S101, the method includes:

[0111] S301. In response to a refrigeration mode triggering event of the sample cold chamber, control the refrigeration module to start, and control the flow rate set value of the target gas in the reflux pipeline to be a preset precooling flow rate.

[0112] Among them, the refrigeration mode of the sample cold chamber can be triggered by obtaining a refrigeration mode triggering instruction input to the control device through the control device, or can be automatically triggered after a preset time interval after pipeline cleaning or vacuum pumping of the closed-loop cryogenic control system. At this time, the refrigeration module starts to output cooling capacity, and the flow rate set value of the target gas in the reflux pipeline is set to the preset precooling flow rate so that the system switches to the refrigeration mode, and the pipeline is first precooled.

[0113] The preset precooling flow rate is the flow rate set value of the target gas in the reflux pipeline during the system precooling process. This preset precooling flow rate can be selected as a fixed value to reduce the control difficulty during the precooling process; in an alternative embodiment, this preset precooling flow rate is less than the current target flow rate during the formal refrigeration process in step S101, and is also less than the updated target flow rate in step S105 and the desired flow rate in step S111. That is, this preset precooling flow rate is the minimum flow rate set value of the target gas in the reflux pipeline during the entire closed-loop cryogenic control process. When the flow rate of the target gas is small, under the condition of the same cooling capacity output by the refrigeration module, the target gas can be cooled to a very low temperature faster, so that the cooling capacity output by the refrigeration module can more efficiently cool the target gas at the preset precooling flow rate, greatly improving the precooling efficiency and shortening the precooling time.

[0114] S303. In the state where the target gas is refluxed based on the preset precooling flow rate, with the first preset temperature as the target temperature, adjust the output power of the first heating module according to the temperature of the refrigeration gas in the delivery pipeline and the preset precooling flow rate until the output power of the first heating module reaches the power output steady-state condition.

[0115] The steady-state condition of power output is that when the target gas is refluxed based on a preset precooling flow rate and the temperature of the refrigerating gas is maintained at a first preset temperature, the output power of the first heating module no longer changes or reaches a dynamically stable state. Specifically, it can be that the output power within a preset time interval remains stable or reaches a dynamic stability. For example, in some exemplary embodiments, the output power of the first heating module reaches a stable value or is within a preset stable range and is maintained for 3 minutes or more, then the control device determines that the output power of the first heating module during this precooling process reaches the steady-state condition of power output. In other exemplary embodiments, the difference between the output powers of the first heating module within two adjacent preset time intervals is lower than a preset output power difference, that is, dynamic stability. Among them, when the preset output power difference is equal to 0, it means that the output power of the first heating module no longer changes.

[0116] Among them, the output power of the first heating module during the precooling process is adjusted through the following steps:

[0117] Control the reflux pipeline to reflux the target gas at the preset precooling flow rate;

[0118] Control the first heating module to start;

[0119] Monitor the temperature of the refrigerating gas input by the temperature control device into the conveying pipeline;

[0120] Adjust the output power of the first heating module according to the temperature of the refrigerating gas in the conveying pipeline and the preset precooling flow rate.

[0121] S305, Determine the output power that meets the output steady-state condition as the target precooling power, and control the first heating module to operate at the target precooling power.

[0122] During the precooling process, the preset precooling flow rate is the minimum flow rate setting value during the entire refrigeration process. Correspondingly, when the temperature of the refrigerating gas is controlled to be the first preset temperature, the target precooling power that reaches the steady-state condition of power output during the precooling process is the maximum output power during the entire refrigeration process.

[0123] In this step, the reflux pipeline refluxes the target gas at the preset precooling flow rate, and after the first heating module operates at the target precooling power for a preset precooling time, the precooling process in the system is completed. Among them, the preset precooling time can be set according to actual conditions, and the present invention does not make specific limitations on this.

[0124] S307, Update the flow rate setting value in the reflux pipeline from the preset precooling flow rate increment to the target flow rate.

[0125] After this preset pre-cooling time, the system is already in a relatively low-temperature state. Step S307 is executed to update the flow rate set value increment in the return pipeline to the target flow rate to increase the target flow rate, which is the current target flow rate in step S101, so that the closed-loop low-temperature control system enters the formal refrigeration state and improves the refrigeration power of the refrigeration gas input to the sample cold chamber.

[0126] Specifically, before pre-cooling the system pipeline, the pipeline is cleaned to maintain the atmosphere of the target gas in the pipeline; then, as Figure 7 shown, before starting the refrigeration module, that is, before step S301, the method further includes:

[0127] S402, in response to the refrigeration mode trigger event of the sample cold chamber, control the first communication valve to open to deliver the target gas to the temperature control device.

[0128] S404, when detecting that the target gas is flowing in the return pipeline, control the circulation pump and the bleed valve to open, and control the second communication valve to close for pipeline cleaning.

[0129] S406, when detecting that the cleaning duration reaches the preset cleaning duration, control the bleed valve to close and the second communication valve to open, and control the flow rate set value of the target gas in the return pipeline to the preset cleaning flow rate to trigger the start of the refrigeration module.

[0130] Through steps S402 to S404, the gas inlet pipeline, the delivery pipeline, and the return pipeline are filled with the target gas, and the gas originally existing in the above pipelines is removed from the pipelines to the outside atmosphere through the bleed valve; among them, step S404 lasts for the preset cleaning duration to replace the gas in the pipeline with the target gas as much as possible. Then, when detecting that the cleaning duration reaches the preset cleaning duration, step S406 is executed to close the bleed valve to isolate the pipeline of the closed-loop low-temperature control system from the outside atmosphere, open the second communication valve to make the gas inlet pipeline, the delivery pipeline, and the return pipeline form a connected closed-loop pipeline. At this time, control the flow rate value of the target gas in the return pipeline to the preset cleaning flow rate to keep the atmosphere of the target gas in the pipeline of the closed-loop low-temperature control system all the time, with high cleaning efficiency and good stability of maintaining the atmosphere of the target gas in the system.

[0131] In some embodiments, the preset cleaning duration is 10 to 20 minutes; it can be understood that the preset cleaning duration can be any point value within 10 to 20 minutes. Exemplarily, the preset cleaning duration can be 10 minutes, 11 minutes, 12 minutes, 15 minutes, 20 minutes, etc. On the one hand, it enables the target gas to fully clean the pipeline, and on the other hand, it avoids waste of the target gas and saves costs.

[0132] In some embodiments, the preset cleaning flow rate is a relatively large flow rate setting value during the control process of the closed-loop cryogenic control system. The preset cleaning flow rate can be greater than the desired flow rate, so that the pipeline of the closed-loop cryogenic control system can be cleaned in a relatively large flow rate setting value, which is beneficial to improving the cleaning efficiency.

[0133] Specifically, before controlling the circulation pump and the bleed valve to open and the second communication valve to close for pipeline cleaning when it is detected that the target gas is flowing in the return pipeline, that is, before step S404, the method further includes:

[0134] Controlling the pressure reducing valve to open;

[0135] Monitoring the current pressure in the gas inlet pipeline;

[0136] Adjusting the opening degree of the pressure reducing valve according to the difference between the current pressure in the gas inlet pipeline and the preset pressure until the pressure in the gas inlet pipeline reaches the preset pressure.

[0137] Wherein, the preset pressure refers to the pressure setting value for maintaining the safe operation of the closed-loop cryogenic control system. The preset pressure is close to the external atmospheric pressure. In some alternative embodiments, the preset pressure is 0 to 0.1 bar, maintaining a weak pressure difference between the two sides of the pressure reducing valve to prevent a large amount of hot gas from surging into the refrigeration cavity instantaneously when the inflation valve is opened. At the same time, it is also beneficial to maintaining the overall safety of the closed-loop cryogenic control system and extending its service life.

[0138] In some embodiments, the current pressure can be monitored by a pressure monitoring element, and the current pressure is sent to the control device by the pressure monitoring element, so that the control device can determine the difference between the current pressure and the preset pressure according to the current pressure to adjust the opening degree of the pressure reducing valve, with high control accuracy and good safety; in other embodiments, the pressure monitoring element can directly monitor the difference between the current pressure and the preset pressure, such as a differential pressure gauge, then the pressure detection element can directly send the pressure difference to the control device, enabling the control device to directly adjust the opening degree of the pressure reducing valve according to the pressure difference, with fast response and timely control.

[0139] Specifically, as Figure 8As shown, before controlling the refrigeration module to start, that is, before step S301, the method further includes:

[0140] S501, in response to the refrigeration mode triggering event of the sample cold cavity, control the first vacuum valve, the second vacuum valve and the vacuum pump to open, so as to evacuate the refrigeration outer cavity and the sample outer cavity respectively until the refrigeration outer cavity and the sample outer cavity meet the vacuum conditions.

[0141] This step is carried out before cooling, especially before precooling, that is, first pre-evacuate the refrigeration outer cavity of the temperature control device and the sample outer cavity of the sample cold cavity, so that the refrigeration inner cavity of the temperature control device and the sample inner cavity of the sample cold cavity are both isolated from the outside atmosphere, which can effectively isolate heat exchange, reduce the loss of cold in the refrigeration inner cavity and the sample inner cavity, and greatly improve temperature stability; this pre-evacuation process can be carried out before or after the pipeline cleaning process, or can be carried out synchronously, and the operation between the two does not interfere with each other, which can further save the operation efficiency of the closed-loop low-temperature control system and save time cost.

[0142] Specifically, as Figure 8 shown, the method further includes:

[0143] S503, in response to the heating mode triggering event of the sample cold cavity, if the first vacuum valve, the second vacuum valve and the vacuum pump are in the open state, control the first vacuum valve, the second vacuum valve and the vacuum pump to close.

[0144] Among them, the heating mode of the sample cold cavity can be triggered by the sample replacement event of the sample cold cavity. The control device obtains the sample replacement instruction input to the control device, so as to determine that the sample cold cavity enters the heating mode; it can also be automatically triggered after a certain time in step S111, that is, the heating mode is triggered after the sample in the sample cold cavity is detected.

[0145] If the first vacuum valve, the second vacuum valve and the vacuum pump are already in the closed state, then maintain the closed state of the three.

[0146] S505, in response to the switching event from the heating mode to the refrigeration mode, if the first vacuum valve is in the closed state and the refrigeration outer cavity is in the vacuum state, control the second vacuum valve and the vacuum pump to open.

[0147] After entering the heating mode, the control device controls the vacuum pump to stop evacuating, the first vacuum valve closes, and the refrigeration inner cavity always remains in a vacuum state. Then, when switching back to the refrigeration mode, there is no need to evacuate the refrigeration outer cavity again, which can save energy. The second vacuum valve closes. Since the sample outer cavity is in communication with the atmosphere when the sample cold cavity is replaced, when switching back to the refrigeration mode, the control device opens the vacuum pump and the second vacuum valve to re-evacuate the sample outer cavity after the sample is replaced.

[0148] In addition, if the refrigeration outer cavity is not in a vacuum state, in response to the switching event from the heating mode to the refrigeration mode, the control device opens the first vacuum valve, the second vacuum valve, and the vacuum pump to re-evacuate the refrigeration outer cavity and the sample outer cavity.

[0149] Specifically, when all the samples in the sample cold cavity are detected or the samples in the sample cold cavity need to be replaced, a heating requirement appears to facilitate sampling; as Figure 9 shown, after controlling the reflux pipeline to reflux based on the current target flow rate and controlling the first heating module to operate at the current output power of the first heating module, and repeating the step of monitoring the output power of the first heating module, that is, after step S111, the method further includes:

[0150] S602, in response to the heating mode trigger event, adjust the flow rate setting value of the target gas in the reflux pipeline to the preset heating flow rate, and control the refrigeration module to turn off.

[0151] Among them, the preset heating flow rate is greater than the desired flow rate, so that the target gas in the reflux pipeline circulates at a larger flow rate, accelerating the heating speed of the pipeline in the closed-loop low-temperature control system and shortening the heating time. In an optional embodiment, the preset heating flow rate is set to a fixed value and does not need to be adjusted after setting, reducing the control load of the control device. In some optional embodiments, the preset heating flow rate can be equal to the preset cleaning flow rate, and both are larger flow rate setting values. For example, both the preset heating flow rate and the preset cleaning flow rate are 12 L / min, which is simple and convenient to control and has a high heating efficiency.

[0152] S604, taking the third preset temperature as the target temperature of the refrigeration gas in the delivery pipeline, adjust the heating power of the first heating module according to the preset heating flow rate and the current temperature of the refrigeration gas in the delivery pipeline until the temperature of the refrigeration gas in the delivery pipeline reaches the third preset temperature.

[0153] S606, taking the fourth preset temperature as the target temperature of the refrigeration gas input to the sample cold cavity, adjust the heating power of the second heating module according to the preset heating flow rate and the current temperature of the refrigeration gas input to the sample cold cavity until the temperature of the refrigeration gas in the sample cold cavity reaches the fourth preset temperature.

[0154] Steps S604 and S606 are executed in parallel respectively, and there is no sequence between them; wherein, the third preset temperature is the temperature set value required for the temperature control device after heating up, and the fourth preset temperature is the temperature set value required for the sample cold chamber after heating up.

[0155] Before heating up, the sample cold chamber is still in a low-temperature environment. When sampling or closing the system, it needs to be heated up to a temperature close to room temperature; at least one of the third preset temperature and the fourth preset temperature is 277K - 293K; taking the third preset temperature as an example, it can be understood that the third preset temperature can be any point value within 277K - 293K. Exemplarily, the third preset temperature can be 277K, 282K, 285K, 287K, 293K, etc., to prevent phenomena such as condensation; preferably, at least one of the third preset temperature and the fourth preset temperature is 283K - 293K, which is lower than the conventional room temperature; during the heating-up process, the temperature rises rapidly in the early stage of heating up, and slowly in the later stage of heating up, and the heat insulation effect of the vacuum environment disappears. The temperature set value is close to the external environmental temperature, which can reduce the heat exchange between the temperature control device and the target gas in the sample cold chamber and the air at room temperature outside, prevent the situation that the temperature in the sample cold chamber is difficult to reach the third preset temperature, and at the same time, prevent the later heating-up speed from being very slow due to too high a third preset temperature and wasting a large amount of heating-up time, thus improving the heating-up efficiency.

[0156] S608, control the first heating module, the second heating module, and the vacuum control module to close.

[0157] When the temperatures in the closed-loop low-temperature control system reach their respective corresponding preset temperatures, the first heating module, the second heating module, and the vacuum control module can be controlled to close, so that the closed-loop low-temperature control system stops running as a whole.

[0158] Specifically, in some alternative embodiments, before step S608, the method further includes:

[0159] Monitor the current pressure in the gas inlet pipeline;

[0160] In the case where it is monitored that the current pressure is lower than the preset safety pressure, execute the step of controlling the first heating module, the second heating module, and the vacuum control module to close;

[0161] In the case where it is monitored that the current pressure is higher than the preset safety pressure, control the air release valve to open until the pressure in the gas inlet pipeline is lower than the preset safety pressure 。

[0162] Among them, the preset safety pressure refers to the upper limit value of the pressure that the pipeline in the closed-loop low-temperature control system can withstand to maintain the safety of the closed-loop low-temperature control system; in an alternative embodiment, the preset safety pressure is equal to the preset pressure, and the safety performance is good.

[0163] During the heating process, the pressure corresponding to the target gas increases, and the preset heating flow rate is relatively large, and the flow rate of the target gas in the return pipeline is also large, which will also cause the pressure in the pipeline to increase, posing a potential risk to the safety of the pipeline. Therefore, when it is detected that the current pressure is higher than the preset safety pressure, the control air release valve is opened to relieve the pressure and reduce the risk of pipeline explosion.

[0164] In some embodiments, at least one safety valve is further provided in the closed-loop low-temperature control system. The safety valve can automatically open and close. When the current pressure in the pipeline reaches the pressure critical value that the safety valve can withstand, the safety valve is opened under the action of pressure so that the target gas in the pipeline can be discharged to reduce the pressure in the pipeline. When the pressure in the pipeline drops to the lower limit value of the pressure that can open the safety valve, the safety valve automatically closes, greatly improving the system safety.

[0165] The following introduces the specific process of the closed-loop low-temperature control method in a specific embodiment, as Figure 10 and Figure 11 shown, where the values of each control parameter are only for illustration and do not limit the present invention.

[0166] S1. In response to the refrigeration mode trigger event of the sample cold chamber, control the first communication valve to open to deliver the target gas to the temperature control device.

[0167] S2. Control the pressure reducing valve to open.

[0168] S3. Monitor the current pressure in the gas inlet pipeline through the pressure monitoring element.

[0169] S4. Adjust the opening degree of the pressure reducing valve according to the difference between the current pressure in the gas inlet pipeline and the preset pressure until the pressure in the gas inlet pipeline reaches the preset pressure of 0 - 0.1 bar.

[0170] S5. Determine whether the pressure in the gas inlet pipeline reaches the preset pressure of 0 - 0.1 bar.

[0171] S6. If the pressure in the gas inlet pipeline reaches 0 - 0.1 bar, in the state where it is detected that the target gas is flowing in the return pipeline, control the circulation pump and the air release valve to open, and control the second communication valve to close for pipeline cleaning.

[0172] If the pressure in the gas inlet pipeline does not reach 0 - 0.1 bar, return to step S4.

[0173] S7, when it is detected that the cleaning duration reaches 10 minutes, control the air release valve to close and the second communication valve to open, and control the flow rate set value of the target gas in the reflux pipeline to be 12 L / min to trigger the start of the refrigeration module.

[0174] S8, in response to the refrigeration mode trigger event of the sample cold chamber, control the first vacuum valve, the second vacuum valve and the vacuum pump to open to evacuate the refrigeration outer chamber and the sample outer chamber respectively until the refrigeration outer chamber and the sample outer chamber meet the vacuum conditions.

[0175] S9, determine whether there is a trigger event for the heating mode of the sample cold chamber.

[0176] S10, if there is a trigger event for the heating mode of the sample cold chamber, in response to the trigger event for the heating mode of the sample cold chamber, if the first vacuum valve, the second vacuum valve and the vacuum pump are in the open state, control the first vacuum valve, the second vacuum valve and the vacuum pump to close.

[0177] Otherwise, return to step S8 to maintain the vacuum conditions of the refrigeration outer chamber and the sample outer chamber.

[0178] S11, determine whether there is a switching event from the heating mode to the refrigeration mode.

[0179] S12, if there is a switching event from the heating mode to the refrigeration mode, in response to the switching event from the heating mode to the refrigeration mode, if the first vacuum valve is in the closed state and the refrigeration outer chamber is in the vacuum state, control the second vacuum valve and the vacuum pump to open.

[0180] Otherwise, return to step S10 to maintain the first vacuum valve, the second vacuum valve and the vacuum pump in the closed state.

[0181] S13, in response to the refrigeration mode trigger event of the sample cold chamber, control the refrigeration module to start, and control the preset precooling flow rate of the target gas in the reflux pipeline to be 6 L / min.

[0182] S14, control the reflux pipeline to reflux the target gas at the preset precooling flow rate.

[0183] S15, control the first heating module to start.

[0184] S16, monitor the temperature of the refrigerating gas input by the temperature control device into the conveying pipeline.

[0185] S17, in the state of refluxing the target gas based on the preset precooling flow rate, with 4.5 K as the target temperature, adjust the output power of the first heating module according to the temperature of the refrigerating gas in the conveying pipeline and the preset precooling flow rate until the output power of the first heating module reaches the target precooling power and maintains for 3 minutes or more to meet the steady-state condition of power output.

[0186] S18, determine whether the output power of the first heating module reaches the target precooling power and maintain it for 3 minutes or more.

[0187] S19, if the judgment result is yes, determine the output power that meets the output steady-state condition as the target precooling power, and control the first heating module to operate at the target precooling power; this target precooling power is the maximum output power of the first heating module during the entire adjustment process.

[0188] Otherwise, return to step S17.

[0189] S20, update the flow rate set value in the return pipeline from the preset precooling flow rate increment to the target flow rate.

[0190] S21, when the sample cold cavity is in the refrigeration mode, obtain the current temperature of the refrigerating gas currently delivered by the temperature control device to the delivery pipeline and the current target flow rate.

[0191] S22, adjust the output power of the first heating module according to the current temperature of the refrigerating gas in the delivery pipeline, the first preset temperature of 4.5K, and the current target flow rate until the temperature of the refrigerating gas in the delivery pipeline reaches 4.5K.

[0192] S23, during the process of controlling the temperature of the refrigerating gas in the delivery pipeline to 4.5K, monitor the output power of the first heating module.

[0193] S24, determine whether the output power of the first heating module is higher than or equal to 0.5W.

[0194] S25, when it is monitored that the output power of the first heating module is higher than or equal to 0.5W, update the current target flow rate with a preset increment of 0.3L / min to obtain the updated target flow rate.

[0195] S26, repeat the above output power adjustment steps of the first heating module based on the updated target flow rate to control the temperature of the refrigerating gas in the delivery pipeline to 4.5K.

[0196] S27, when it is monitored that the output power of the first heating module is lower than 0.5W, use the current target flow rate as the desired flow rate, control the return pipeline to return based on the current target flow rate, control the first heating module to operate at the current output power of the first heating module, and repeat the step of monitoring the output power of the first heating module.

[0197] S28, obtain the current temperature of the refrigerating gas input into the sample cold cavity.

[0198] S29. Set the second preset temperature as the target temperature of the refrigerating gas input into the sample cold chamber, and adjust the output power of the second heating module according to the desired flow rate and the current temperature of the refrigerating gas input into the sample cold chamber until the temperature of the refrigerating gas input into the sample cold chamber reaches the second preset temperature.

[0199] S30. Obtain the current temperature of the refrigerating gas input into the sample cold stage.

[0200] S31. Set the cold stage preset temperature as the target temperature of the refrigerating gas input into the sample cold stage, and adjust the output power of the third heating module according to the desired flow rate and the current temperature of the refrigerating gas input into the sample cold stage until the temperature of the refrigerating gas input into the sample cold stage reaches the cold stage preset temperature.

[0201] S32. In response to the heating mode trigger event, adjust the flow rate set value of the target gas in the return pipeline to the preset heating flow rate, and control the refrigeration module to turn off.

[0202] S33. Set the third preset temperature as the target temperature of the refrigerating gas in the delivery pipeline, and adjust the heating power of the first heating module according to the preset heating flow rate and the current temperature of the refrigerating gas in the delivery pipeline until the temperature of the refrigerating gas in the delivery pipeline reaches the third preset temperature.

[0203] S34. Set the fourth preset temperature as the target temperature of the refrigerating gas input into the sample cold chamber, and adjust the heating power of the second heating module according to the preset heating flow rate and the current temperature of the refrigerating gas input into the sample cold chamber until the temperature of the refrigerating gas in the sample cold chamber reaches the fourth preset temperature.

[0204] S38. Monitor the current pressure in the gas inlet pipeline.

[0205] S36. Determine whether the current pressure in the gas inlet pipeline is higher than the preset safety pressure.

[0206] S37. When it is monitored that the current pressure is higher than the preset safety pressure, control the gas release valve to open until the pressure in the gas inlet pipeline is lower than the preset safety pressure. 。

[0207] S38. When it is monitored that the current pressure is lower than the preset safety pressure, determine whether the temperature of the refrigerating gas in the delivery pipeline reaches the third preset temperature, and determine whether the temperature of the refrigerating gas in the sample cold chamber reaches the fourth preset temperature.

[0208] S39. If the temperature of the refrigerating gas in the delivery pipeline reaches the third preset temperature and the temperature of the refrigerating gas in the sample cold chamber reaches the fourth preset temperature, control the first heating module, the second heating module and the vacuum control module to turn off.

[0209] Otherwise, return to step S32 to maintain the temperature increase step.

[0210] As can be seen from the above embodiments, the closed-loop low-temperature control method in the embodiments of the present invention has the following beneficial effects:

[0211] The present invention uses a refrigeration module to generate cold, and regulates the temperature of the temperature control device by regulating the target flow rate of the target gas flowing back to the temperature control device and the output power of the first heating module. The heat generated by the heating power of the first heating module and the heat carried by the target flow rate of the target gas delivered to the temperature control device are neutralized with the cold generated by the refrigeration module together, dynamically maintaining the refrigerating gas delivered from the temperature control device to the delivery pipeline to reach the first preset temperature. When the target flow rate reaches the maximum flow rate setting value allowed at the first preset temperature, the refrigerating gas is delivered to the sample cold chamber to effectively cool the sample in the sample cold chamber. The flow rate of the refrigerating gas is large, and the loss of cold in the delivery pipeline is small, which can effectively improve the temperature accuracy and temperature stability; in the case of multiple uncontrollable variables in the closed-loop low-temperature control system, the closed-loop low-temperature control method enables the temperature control device to achieve a controllable and stable output of cold, with a high degree of automation, fast regulation of the target flow rate and the output power of the first heating module, good timeliness, and high accuracy, which is beneficial to maintaining the temperature stability and operation stability of the entire closed-loop low-temperature control system.

[0212] Corresponding to the closed-loop low-temperature control method provided in the above embodiments of the present invention, the control device in the closed-loop low-temperature control system provided in the embodiments of the present invention can implement the closed-loop low-temperature control method in the above method embodiments. The control device may include:

[0213] An acquisition module, configured to acquire the current temperature and the current target flow rate of the refrigerating gas currently delivered from the temperature control device to the delivery pipeline when the sample cold chamber is in the refrigeration mode. The first preset temperature refers to the temperature target value of the refrigerating gas input from the temperature control device to the delivery pipeline, and the current target flow rate refers to the current flow rate setting value of the target gas in the return pipeline;

[0214] A power adjustment module, configured to adjust the output power of the first heating module according to the current temperature of the refrigerating gas in the delivery pipeline, the first preset temperature, and the current target flow rate until the temperature of the refrigerating gas in the delivery pipeline reaches the first preset temperature;

[0215] A monitoring module, configured to monitor the output power of the first heating module during the process of controlling the temperature of the refrigerating gas in the delivery pipeline to be the first preset temperature;

[0216] An update module, configured to update the current target flow rate by a preset increment to obtain an updated target flow rate when it is detected that the output power of the first heating module is higher than or equal to the power upper limit value;

[0217] A loop module, configured to repeat the above-mentioned output power adjustment step of the first heating module based on the updated target flow rate to control the temperature of the refrigerating gas in the delivery pipeline to be the first preset temperature.

[0218] It should be noted that, when implementing its functions, the control device provided in the above embodiment is only illustrated by the division of the above-mentioned functional modules. In practical applications, the above functions can be allocated to different functional modules according to needs, that is, the internal structure of the device is divided into different functional modules to complete all or part of the functions described above. In addition, the control device provided in the above embodiment and the method embodiment belong to the same concept, and the specific implementation process can be seen in the method embodiment, which will not be elaborated here.

[0219] The closed-loop low-temperature control system is controlled by a control device, which includes a processor and a memory. Among them, the processor (or CPU (Central Processing Unit, central processor)) is the core component of the control device, and its function is mainly to interpret the memory instructions and process the data fed back by each module; the structure of the processor is roughly divided into an arithmetic logic component and a register component, etc. The arithmetic logic component mainly performs relevant logical calculations (such as shift operations, logical operations, fixed-point or floating-point arithmetic operations and address operations, etc.), and the register component is used to temporarily store instructions, data and addresses.

[0220] The memory is a memory device, which can be used to store software programs and modules. The processor executes various functional applications and data processing by running the software programs and modules stored in the memory. The memory mainly includes a program storage area and a data storage area. Among them, the program storage area can store an operating system, which can include but is not limited to: Windows system (an operating system), Linux (an operating system), etc., and the present invention does not make any limitation in this regard; in addition, application programs required for functions can also be stored, for example, at least one instruction suitable for being loaded and executed by the processor is also stored in the storage space of the memory, and these instructions can be one or more computer programs (including program codes); and, the data storage area can store data created according to the use of the device, etc.; correspondingly, the memory can also include a memory controller to provide the processor with access to the memory.

[0221] An embodiment of the present invention further provides a storage medium, in which at least one instruction or at least one program segment is stored, and the at least one instruction or the at least one program segment is loaded and executed by a processor to implement the closed-loop low-temperature control method described above; optionally, the storage medium may be located in at least one of multiple network servers in a computer network; in addition, the storage medium may include, but is not limited to, various storage media that can store program codes, such as random access memory (RAM), read-only memory (ROM), non-volatile memory (NVM), USB flash drives, external hard drives, disk storage devices, flash memory devices, and other volatile solid-state storage devices.

[0222] It should be noted that the above sequence of embodiments of the present invention is only for description and does not represent the superiority or inferiority of the embodiments. And the above specific embodiments of this specification have been described. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recited in the claims may be executed in a different order than in the embodiments and still achieve the desired result. Additionally, the processes depicted in the drawings do not necessarily require the specific order or sequential order shown to achieve the desired result. In certain embodiments, multitasking and parallel processing are also possible or may be advantageous.

[0223] Each embodiment in this specification is described in a progressive manner. The same or similar parts among the embodiments can be referred to each other, and each embodiment focuses on the differences from other embodiments. In particular, for the device embodiments, since they are basically similar to the method embodiments, the description is relatively simple, and the relevant parts can be referred to the description of the method embodiments.

[0224] What has been described above are only some embodiments of the present invention and are not used to limit the present invention. Those skilled in the art should understand that the present invention will have various changes and improvements, and any modifications, equivalent replacements, and improvements made in accordance with the present invention fall within the scope of protection required by the present invention.

Claims

1. A closed-loop low-temperature control method, applied to a closed-loop low-temperature control system, characterized in that: The closed-loop low-temperature control system comprises a temperature control device, a delivery pipeline and a reflux pipeline, wherein the gas outlet of the temperature control device, the delivery pipeline, the sample cold chamber, the reflux pipeline and the gas inlet of the temperature control device are connected in sequence, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used to cool down the target gas passing through the temperature control device to form a refrigeration gas delivered to the delivery pipeline, the first heating module is used to heat the refrigeration gas to make the refrigeration gas reach a first preset temperature; the reflux pipeline is used to deliver the heated target gas in the sample cold chamber back to the temperature control device; The method comprises: When the sample cold chamber is in a cooling mode, the current temperature and the current target flow rate of the refrigerant gas currently delivered to the delivery pipeline by the temperature control device are obtained, wherein the first preset temperature refers to the temperature target value of the refrigerant gas input to the delivery pipeline by the temperature control device, and the current target flow rate refers to the current flow setting value of the target gas in the return pipeline; adjusting the output power of the first heating module according to the current temperature of the refrigerant gas in the delivery pipeline, the first preset temperature and the current target flow rate until the temperature of the refrigerant gas in the delivery pipeline reaches the first preset temperature; In the process of controlling the temperature of the refrigerant gas in the delivery pipeline to be a first preset temperature, monitoring the output power of the first heating module; When it is monitored that the output power of the first heating module is higher than or equal to the upper power limit, the current target flow rate is updated by a preset increment to obtain an updated target flow rate; The output power adjustment step of the first heating module is repeated based on the updated target flow rate to control the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature.

2. The closed-loop low-temperature control method according to claim 1, characterized in that: In the process of controlling the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature, after monitoring the output power of the first heating module, the method further includes: When it is monitored that the output power of the first heating module is lower than the power upper limit, the current target flow rate is used as the expected flow rate, and the return pipeline is controlled to reflux based on the current target flow rate and the first heating module is controlled to operate at the current output power of the first heating module, and the step of monitoring the output power of the first heating module is repeated.

3. The closed-loop low-temperature control method according to claim 2, characterized in that: The closed-loop cryogenic control system further includes a second heating module, which is used to heat the refrigerant gas input into the sample cold chamber so that the refrigerant gas reaches a second preset temperature; after the current target flow rate is used as the expected flow rate when the output power of the first heating module is monitored to be lower than the power upper limit, and the reflux pipeline is controlled to reflux based on the current target flow rate and the first heating module is controlled to operate at the current output power of the first heating module, the method further includes: Acquiring the current temperature of the refrigerant gas input into the sample cold chamber; The second preset temperature is used as the target temperature of the refrigerant gas input into the sample cold chamber, and the output power of the second heating module is adjusted according to the expected flow rate and the current temperature of the refrigerant gas input into the sample cold chamber until the temperature of the refrigerant gas input into the sample cold chamber reaches the second preset temperature, wherein the second preset temperature refers to the target value of the sample refrigeration temperature that the refrigerant gas in the sample cold chamber needs to reach.

4. The closed-loop low-temperature control method according to claim 1, characterized in that: When the sample cold chamber is in the cooling mode, before obtaining the current temperature of the refrigerant gas currently delivered to the delivery pipeline by the temperature control device, the first preset temperature and the current target flow rate, the method includes: In response to a refrigeration mode triggering event of the sample cold chamber, controlling the refrigeration module to start, and controlling the flow setting value of the target gas in the reflux pipeline to be a preset pre-cooling flow; In a state where the target gas is refluxed based on the preset precooling flow rate, taking the first preset temperature as the target temperature, adjusting the output power of the first heating module according to the temperature of the refrigerant gas in the delivery pipeline and the preset precooling flow rate, until the output power of the first heating module reaches a power output steady-state condition; determining the output power satisfying the output steady-state condition as the target pre-cooling power, and controlling the first heating module to operate at the target pre-cooling power; The flow setting value in the return line is updated from the preset precooling flow increment to the target flow.

5. The closed-loop low-temperature control method according to claim 4, characterized in that: The closed-loop cryogenic control system comprises a flow control module, which comprises a first connecting valve, a second connecting valve, a venting valve and a circulation pump, wherein the first connecting valve is arranged in the gas inlet pipeline of the temperature control device; the gas outlet of the sample cold chamber, the circulation pump, the second connecting valve and the gas inlet of the temperature control device are connected in sequence by pipelines to form the reflux pipeline, and the venting valve is arranged between the second connecting valve and the circulation pump, with one end being connected to the reflux pipeline and the other end being connected to the outside; Before controlling the refrigeration module to start, the method further includes: In response to a refrigeration mode triggering event of the sample cold chamber, controlling the first communication valve to open so as to deliver the target gas to the temperature control device; When the target gas is detected flowing in the reflux pipeline, the circulation pump and the air release valve are controlled to be opened, and the second connecting valve is controlled to be closed, so as to clean the pipeline; When it is detected that the cleaning time reaches the preset cleaning time, the air release valve is controlled to be closed and the second connecting valve is controlled to be opened, and the flow setting value of the target gas in the return pipeline is controlled to be the preset cleaning flow to trigger the refrigeration module to start.

6. The closed-loop low-temperature control method according to claim 5, characterized in that: The flow control module further includes a pressure reducing valve, which is disposed in the gas inlet pipeline; before the target gas is detected to flow in the reflux pipeline, the circulation pump and the air release valve are controlled to be opened, and the second connecting valve is controlled to be closed to clean the pipeline, the method further includes: Controlling the pressure reducing valve to open; monitoring the current pressure in the gas inlet line; The opening of the pressure reducing valve is adjusted according to the difference between the current pressure in the gas inlet pipeline and the preset pressure until the pressure in the gas inlet pipeline reaches the preset pressure.

7. The closed-loop low-temperature control method according to claim 4, characterized in that: The temperature control device is provided with a refrigeration inner cavity for accommodating the target gas and a refrigeration outer cavity wrapped outside the refrigeration inner cavity, the sample cold cavity is provided with a sample inner cavity for placing the sample and a sample outer cavity wrapped outside the sample inner cavity, the closed-loop low-temperature control system includes a vacuum control module, the vacuum control module includes a first vacuum valve, a second vacuum valve and a vacuum pump, the vacuum pump is connected to the refrigeration outer cavity through the first vacuum valve, and the vacuum pump is connected to the sample outer cavity through the second vacuum valve; before controlling the refrigeration module to start, the method further includes: In response to a refrigeration mode triggering event of the sample cold chamber, the first vacuum valve, the second vacuum valve and the vacuum pump are controlled to open, so as to evacuate the refrigeration outer chamber and the sample outer chamber respectively until the refrigeration outer chamber and the sample outer chamber meet vacuum conditions.

8. The closed-loop low-temperature control method according to claim 7, characterized in that: The method further comprises: In response to a temperature rise mode triggering event of the sample cold chamber, if the first vacuum valve, the second vacuum valve and the vacuum pump are in an open state, controlling the first vacuum valve, the second vacuum valve and the vacuum pump to be closed; In response to a switching event from a heating mode to a cooling mode, if the first vacuum valve is in a closed state and the cooling outer chamber is in a vacuum state, the second vacuum valve and the vacuum pump are controlled to open.

9. The closed-loop low-temperature control method according to claim 7, characterized in that: After the steps of controlling the reflux line to reflux based on the current target flow rate and controlling the first heating module to operate at the current output power of the first heating module, and repeating the steps of monitoring the output power of the first heating module, the method further includes: In response to a temperature rise mode trigger event, adjusting the flow setting value of the target gas in the return line to a preset temperature rise flow, and controlling the refrigeration module to be turned off; Taking a third preset temperature as the target temperature of the refrigerant gas in the delivery pipeline, adjusting the heating power of the first heating module according to the preset temperature increase flow rate and the current temperature of the refrigerant gas in the delivery pipeline, until the temperature of the refrigerant gas in the delivery pipeline reaches the third preset temperature; Taking a fourth preset temperature as the target temperature of the refrigerant gas input into the sample cold chamber, adjusting the heating power of the second heating module according to the preset temperature increase flow rate and the current temperature of the refrigerant gas input into the sample cold chamber, until the temperature of the refrigerant gas in the sample cold chamber reaches the fourth preset temperature; Control the first heating module, the second heating module and the vacuum control module to be turned off.

10. A closed-loop low-temperature control system, characterized in that: The closed-loop low-temperature control system comprises a temperature control device, a delivery pipeline, a reflux pipeline and a control device, wherein the gas outlet of the temperature control device, the delivery pipeline, the sample cold chamber, the reflux pipeline and the gas inlet of the temperature control device are connected in sequence, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used to cool down the target gas passing through the temperature control device to form a refrigeration gas delivered to the delivery pipeline, the first heating module is used to heat the refrigeration gas to make the refrigeration gas reach a first preset temperature; the reflux pipeline is used to deliver the target gas after the temperature is increased in the sample cold chamber back to the temperature control device; The control device comprises: an acquisition module, for acquiring, when the sample cold chamber is in a cooling mode, a current temperature and a current target flow rate of the refrigerant gas currently delivered to the delivery pipeline by the temperature control device, wherein the first preset temperature refers to a temperature target value of the refrigerant gas input to the delivery pipeline by the temperature control device, and the current target flow rate refers to a current flow setting value of the target gas in the return pipeline; a power regulating module, configured to regulate the output power of the first heating module according to the current temperature of the refrigerant gas in the delivery pipeline, the first preset temperature and the current target flow rate, until the temperature of the refrigerant gas in the delivery pipeline reaches the first preset temperature; a monitoring module, configured to monitor the output power of the first heating module during the process of controlling the temperature of the refrigerant gas in the delivery pipeline to be a first preset temperature; An updating module, configured to update the current target flow rate by a preset increment to obtain an updated target flow rate when the output power of the first heating module is detected to be higher than or equal to the upper power limit; A circulation module is used to repeat the output power adjustment step of the first heating module based on the updated target flow rate to control the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature.

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