Closed cycle cryogenic control method and system

Abstract

The application provides a closed-loop low-temperature control method and system, comprising obtaining a current temperature and a current target flow rate of refrigerant gas currently delivered by a temperature control device to a delivery pipeline; adjusting an output power of a first heating module according to the current temperature, a first preset temperature and the current target flow rate, until the temperature of the refrigerant gas reaches the first preset temperature; monitoring the output power of the first heating module during the process of controlling the temperature of the refrigerant gas to be the first preset temperature; updating the current target flow rate by a preset increment to obtain an updated target flow rate in the case that the output power is higher than an upper limit value; and repeating the output power adjusting step based on the updated target flow rate to control the temperature of the refrigerant gas to be the first preset temperature. The application uses a refrigeration module to generate cold energy, and dynamically maintains the temperature of the refrigerant gas by regulating the target flow rate and the output power of the first heating module, so that the automation degree is high and the system operation stability is good.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of low-temperature control, and in particular to a closed-loop low-temperature control method and system. BACKGROUND

[0002] In the existing closed-loop liquefaction device, a long time is required after starting to liquefy the refrigeration medium, and the newly generated refrigeration liquid cannot be directly used for cooling of external equipment, but needs to be transferred to an additional storage device, and there is a loss of cold energy in the transfer process. In addition, some closed-loop low-temperature devices directly cool the refrigeration medium to form refrigeration gas through a temperature control device, and then directly transmit the refrigeration gas to a continuous flow thermostat to achieve closed-loop low-temperature control, which is fast and does not require external storage. However, the cold energy generated by the refrigeration module in the temperature control device is uncontrollable, and many control parameters need to be adjusted to maintain the low-temperature environment of the device, and the control parameters are highly dependent on each other. SUMMARY

[0003] In view of the problems in the prior art, the present application provides a closed-loop low-temperature control method and system, which can dynamically maintain the temperature accuracy and temperature stability of the refrigeration gas delivered by the temperature control device, has high automation degree, and is accurate and reliable in regulation and control. The technical solution is as follows:

[0004] In one aspect, the present application provides a closed-loop low-temperature control method applied to a closed-loop low-temperature control system, wherein the closed-loop low-temperature control system comprises a temperature control device, a delivery pipeline, and a return pipeline, a gas outlet of the temperature control device, the delivery pipeline, a sample cooling cavity, the return pipeline, and a gas inlet of the temperature control device are sequentially connected, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used for cooling a target gas passing through the temperature control device to form refrigeration gas delivered to the delivery pipeline, and the first heating module is used for heating the refrigeration gas so that the refrigeration gas reaches a first preset temperature; the return pipeline is used for delivering the target gas warmed in the sample cooling cavity back to the temperature control device; and the method comprises:

[0005] In the case that the sample cooling cavity is in a refrigeration mode, the current temperature of the refrigeration gas currently delivered by the temperature control device to the delivery pipeline and the current target flow rate are obtained, the first preset temperature refers to the temperature target value of the refrigeration gas input by 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;

[0006] The output power of the first heating module is adjusted according to the current temperature of the refrigeration gas in the delivery pipeline, the first preset temperature, and the current target flow rate, so that the temperature of the refrigeration gas in the delivery pipeline reaches the first preset temperature.

[0007] monitoring 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 the first preset temperature;

[0008] updating the current target flow rate by a preset increment to obtain an updated target flow rate in a case where the output power of the first heating module is monitored to be higher than or equal to the upper limit value of the power;

[0009] repeating the output power adjustment 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.

[0010] Further, after the monitoring of 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 the first preset temperature, the method further comprises:

[0011] 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 in a case where the output power of the first heating module is monitored to be lower than the upper limit value of the power, and repeating the monitoring of the output power of the first heating module.

[0012] Further, the closed-cycle low-temperature control system further comprises a second heating module for heating the refrigerant gas input into the sample cold cavity to make the refrigerant gas reach a second preset temperature; after the current target flow rate is taken as the expected flow rate and the return pipeline is controlled to return 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 in a case where the output power of the first heating module is monitored to be lower than the upper limit value of the power, the method further comprises:

[0013] obtaining a current temperature of the refrigerant gas input into the sample cold cavity;

[0014] taking the second preset temperature as a target temperature of the refrigerant gas input into the sample cold cavity, adjusting the output power of the second heating module according to the expected flow rate and the current temperature of the refrigerant gas input into the sample cold cavity, so that the temperature of the refrigerant gas input into the sample cold cavity reaches the second preset temperature, and the second preset temperature refers to a target value of a sample refrigeration temperature required to be reached by the refrigerant gas in the sample cold cavity.

[0015] Further, before the acquiring the current temperature of the refrigerant gas currently delivered into the delivery pipeline by the temperature control device, the first preset temperature and the current target flow rate in the case that the sample cold cavity is in the refrigeration mode, the method comprises:

[0016] In response to the refrigeration mode trigger event of the sample cold cavity, the refrigeration module is controlled to start, and the flow rate set value of the target gas in the return pipeline is controlled to be the preset pre-cooling flow rate.

[0017] In the state of returning the target gas based on the preset pre-cooling flow rate, the first preset temperature is taken as the target temperature, the output power of the first heating module is adjusted according to the temperature of the refrigerant gas in the delivery pipeline and the preset pre-cooling flow rate, and the output power of the first heating module reaches the power output steady state condition.

[0018] The output power meeting the output steady state condition is determined as the target pre-cooling power, and the first heating module is controlled to operate at the target pre-cooling power.

[0019] The flow rate set value in the return pipeline is updated from the preset pre-cooling flow rate to the target flow rate.

[0020] Further, the closed-cycle low-temperature control system comprises a flow control module, the flow control module comprises a first communication valve, a second communication valve, a gas release valve and a circulating pump, the first communication valve is arranged in the gas inlet pipeline of the temperature control device; the gas outlet of the sample cold cavity, the circulating pump, the second communication valve and the gas inlet of the temperature control device are sequentially connected in pipeline to form the return pipeline, the gas release valve is arranged between the second communication valve and the circulating pump, one end of the gas release valve is connected with the return pipeline, and the other end of the gas release valve is connected with the outside; before the control of the refrigeration module starts, the method further comprises:

[0021] In response to the refrigeration mode trigger event of the sample cold cavity, the first communication valve is controlled to be opened to deliver the target gas to the temperature control device;

[0022] In the state of detecting that the target gas flows in the return pipeline, the circulating pump and the gas release valve are controlled to be opened, and the second communication valve is controlled to be closed to perform pipeline cleaning;

[0023] In the case that the cleaning duration reaches the preset cleaning duration, the gas release valve is controlled to be closed and the second communication valve is controlled to be opened, and the flow rate set value of the target gas in the return pipeline is controlled to be the preset cleaning flow rate to trigger the refrigeration module to start.

[0024] Further, the flow control module further comprises a pressure reducing valve, which is arranged in the gas inlet pipeline; before the step of controlling the circulating pump and the gas releasing valve to be opened and the second communication valve to be closed for pipeline cleaning under the condition that the target gas is detected to flow in the return pipeline, the method further comprises:

[0025] controlling the pressure reducing valve to be opened;

[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 a 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 for 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 for covering the sample inner cavity, and the closed-cycle low-temperature control system comprises a vacuum control module, the vacuum control module comprises a first vacuum valve, a second vacuum valve and a vacuum pump, the vacuum pump is in openable and closeable communication with the refrigeration outer cavity through the first vacuum valve, and the vacuum pump is in openable and closeable communication with the sample outer cavity through the second vacuum valve; before the step of controlling the refrigeration module to be started, the method further comprises:

[0029] in response to a refrigeration mode trigger event of the sample cold cavity, controlling the first vacuum valve, the second vacuum valve and the vacuum pump to be opened, so as to respectively vacuumize the refrigeration outer cavity and the sample outer cavity until the refrigeration outer cavity and the sample outer cavity satisfy a vacuum condition.

[0030] Further, the method further comprises:

[0031] in response to a sample cold cavity temperature rising mode trigger event, if the first vacuum valve, the second vacuum valve and the vacuum pump are in an opened state, controlling the first vacuum valve, the second vacuum valve and the vacuum pump to be closed;

[0032] in response to a switching event from a temperature rising mode to a 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 be opened.

[0033] Further, after the step of controlling the return pipeline to return based on the current target flow 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 comprises:

[0034] in response to a temperature rising mode trigger event, adjusting a flow set value of the target gas in the return pipeline to a preset temperature rising flow, and controlling the refrigeration module to be closed;

[0035] taking a third preset temperature as a target temperature of the refrigeration gas in the delivery pipeline, adjusting a heating power of the first heating module according to the preset temperature rising flow and a 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;

[0036] taking a fourth preset temperature as a target temperature of the refrigeration gas input into the sample cooling cavity, adjusting a heating power of the second heating module according to the preset temperature rising flow and a current temperature of the refrigeration gas input into the sample cooling cavity, until the temperature of the refrigeration gas in the sample cooling cavity reaches the fourth preset temperature;

[0037] controlling the first heating module, the second heating module and the vacuum control module to be closed.

[0038] In another aspect, the present application provides a closed cycle cryogenic control system, which comprises a temperature control device, a delivery pipeline, a return pipeline and a control device, a gas outlet of the temperature control device, the delivery pipeline, a sample cooling cavity, the return pipeline and a gas inlet of the temperature control device are sequentially communicated, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used for cooling a target gas passing through the temperature control device to form refrigeration gas delivered to the delivery pipeline, and the first heating module is used for heating the refrigeration gas so that the refrigeration gas reaches a first preset temperature; the return pipeline is used for delivering the target gas warmed in the sample cooling cavity back to the temperature control device; and the control device comprises:

[0039] a obtaining module, which is used for obtaining a current temperature and a current target flow of the refrigeration gas currently delivered by the temperature control device into the delivery pipeline when the sample cooling cavity is in a refrigeration mode, the first preset temperature is a temperature target value of the refrigeration gas input by the temperature control device into the delivery pipeline, and the current target flow is a current flow set value of the target gas in the return pipeline;

[0040] a power adjusting module, which is used for adjusting an 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, until the temperature of the refrigeration gas in the delivery pipeline reaches the first preset temperature;

[0041] a monitoring module, which is used for monitoring the output power of the first heating module in the process of controlling the temperature of the refrigeration gas in the delivery pipeline to be the first preset temperature;

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

[0043] a circulating module, configured to repeat the output power adjustment of the first heating module based on the updated target flow to control the temperature of the refrigeration gas in the delivery pipeline to be the first preset temperature.

[0044] In another aspect, the present application provides a storage medium, wherein at least one instruction or at least one program is stored in the storage medium, and the at least one instruction or the at least one program is loaded and executed by a processor to implement the closed-loop cryogenic control method as described above.

[0045] The present application has the following beneficial effects:

[0046] The present application uses a refrigeration module to generate cold energy, and adjusts and controls the target flow of the target gas flowing back to the temperature control device and the output power of the first heating module to control the temperature of the temperature control device. The heat generated by the heating power of the first heating module and the heat carried by the target flow of the target gas delivered to the temperature control device are neutralized with the cold energy generated by the refrigeration module to dynamically maintain the refrigeration gas delivered by the temperature control device to the delivery pipeline at the first preset temperature. The refrigeration gas is delivered to the sample cold cavity to effectively cool the sample in the sample cold cavity, and the temperature accuracy and temperature stability are good. In the case of multiple variables and uncontrollable conditions in the closed-loop cryogenic control system, the closed-loop cryogenic control method enables the temperature control device to achieve a controllable and stable output cold energy, has high automation, fast target flow and output power adjustment of the first heating module, good timeliness, high accuracy, and is conducive to maintaining the temperature stability and operation stability of the entire closed-loop cryogenic control system. BRIEF DESCRIPTION OF DRAWINGS

[0047] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the drawings used in the embodiments will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor.

[0048] Figure 1 The structure diagram of the hardware device in the closed-loop cryogenic control system in one possible embodiment of the present application;

[0049] Figure 2 The structure diagram of the hardware device in the closed-loop cryogenic control system in one possible embodiment of the present application; Figure 1 The enlarged view of the local structure of the delivery pipeline;

[0050] Figure 3A logic structure diagram of a closed cycle cryogenic control method provided for an embodiment of the present application;

[0051] Figure 4 A logic structure diagram of another closed cycle cryogenic control method provided for an embodiment of the present application;

[0052] Figure 5 A logic structure diagram of a temperature control method of a refrigeration gas in a sample cold cavity in a possible implementation provided for an embodiment of the present application;

[0053] Figure 6 A logic structure diagram of a pre-cooling method of a closed cycle cryogenic control system provided for an embodiment of the present application;

[0054] Figure 7 A logic structure diagram of a pipeline cleaning method of a closed cycle cryogenic control system provided for an embodiment of the present application;

[0055] Figure 8 A logic structure diagram of a pre-vacuum method of a closed cycle cryogenic control system provided for an embodiment of the present application;

[0056] Figure 9 A logic structure diagram of a temperature rising method of a closed cycle cryogenic control system provided for an embodiment of the present application;

[0057] Figure 10 A flow chart of a closed cycle cryogenic control method in one specific embodiment of the present application;

[0058] Figure 11 A flow chart of a closed cycle cryogenic control method in another specific embodiment of the present application.

[0059] In which, the reference signs correspond to:

[0060] 1-temperature control device, 11-refrigeration module, 2-conveying pipeline, 3-sample cold cavity, 4-backflow pipeline, 5-flow control module, 51-first communication valve, 52-flow monitoring element, 53-circulating pump, 54-gas release valve, 55-second communication 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 holder. DETAILED DESCRIPTION

[0061] With reference to the drawings of the embodiments of the present application, the technical solutions in the embodiments of the present application will be clearly and completely described, obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments, therefore, cannot be understood as a limitation to the present application. Based on the embodiments in the present application, all the other embodiments obtained by those skilled in the art without creative work, belong to the scope of protection of the present application.

[0062] It should be noted that the terms "first", "second" and the like in the description and claims of the present application and the drawings are used to distinguish similar objects, and do not necessarily indicate a specific order or a chronological sequence. It should be understood that the data thus used can be interchanged under appropriate circumstances, so that the embodiments of the present application can be implemented in an order other than that illustrated below or described below. In addition, the terms "include" and "have" 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 have to be limited to those steps or units clearly listed, but can include other steps or units not clearly listed or inherent to these processes, methods, products or devices.

[0063] In view of the fact that the cooling capacity provided by the refrigeration module in the prior art closed cycle cryogenic system is uncontrollable, in order to maintain the temperature stability of the refrigeration gas output by the temperature control device, multiple control parameters in the system need to be regulated and controlled, but the multiple control parameters are highly dependent on each other, the embodiments of the present application provide a closed cycle cryogenic control method and system, the closed cycle cryogenic control method can be applied to the control device of the closed cycle cryogenic control system provided by the embodiments of the present application, and the control device is regulated and controlled, when a refrigeration demand occurs, in the case that the sample cold cavity is in a refrigeration mode, the control device acquires the current temperature of the refrigeration gas currently delivered to the delivery pipeline by the temperature control device and the current target flow rate; the output power of the first heating module is adjusted according to the current temperature of the refrigeration gas in the delivery pipeline, the first preset temperature and the current target flow rate, so that 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, the output power of the first heating module is monitored; in the case that the output power of the first heating module is higher than or equal to the power upper limit value, 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 refrigeration gas in the delivery pipeline to be the first preset temperature, which is high in automation degree, fast and accurate in regulation and control, and is conducive to maintaining the temperature stability of the entire closed cycle cryogenic control system and improving the temperature control performance of the closed cycle cryogenic control system.

[0064] Specifically, as Figure 1As shown, the closed-loop low-temperature control system provided by the 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 cooling cavity 3, the return pipeline 4, and the gas inlet of the temperature control device 1 are sequentially communicated, so that the target gas and the refrigeration gas formed after the target gas is cooled can circulate in the pipeline, avoiding that the refrigeration time of one side of the sample cooling cavity 3 is limited by the amount of the target gas, and being capable of greatly prolonging the refrigeration time of the sample cooling cavity 3 while saving the amount of the target gas, thereby effectively improving the temperature control performance of the closed-loop low-temperature control system. The target gas and the refrigeration gas are the same gas with different temperatures, which can be helium and nitrogen, and the refrigeration effect is good.

[0065] As shown in the figure, Figure 1 The temperature control device 1 includes a refrigeration module 11 and a first heating module. The refrigeration module 11 can provide cold energy for cooling the target gas passing through the temperature control device 1 to form refrigeration gas delivered to the delivery pipeline 2. The first heating module is used for heating the refrigeration gas to make the refrigeration gas reach a first preset temperature. That is, the target gas entering the temperature control device 1 is first cooled by the refrigeration module 11 to form refrigeration gas, at this time the temperature of the refrigeration gas is lower than the first preset temperature, and then the refrigeration gas is heated by the first heating module to make the temperature of the refrigeration gas rise to the first preset temperature. The refrigeration gas at the first preset temperature is output from the gas outlet of the temperature control device 1. The refrigeration gas at the first preset temperature is delivered from the temperature control device 1 to the delivery pipeline 2 and then to the sample cooling cavity 3, thereby cooling the sample cooling cavity 3. In the sample cooling cavity 3, the refrigeration gas is heated by heat exchange to form heated target gas. The return pipeline 4 is used for delivering the heated target gas in the sample cooling cavity 3 back to the temperature control device 1 for circulating cooling to form refrigeration gas again to cool the sample cooling cavity 3.

[0066] Specifically, the closed-loop low-temperature control system further includes a second heating module for heating the refrigeration gas input into the sample cooling cavity 3 to make the refrigeration gas reach a second preset temperature, thereby further improving the accuracy and stability of the refrigeration temperature of the refrigeration gas in the sample cooling cavity 3.

[0067] Specifically, in an optional embodiment, the closed-loop low-temperature control system further includes a third heating module for heating the refrigeration gas of the sample cooling holder 9 to make the refrigeration gas reach a cold holder preset temperature, thereby improving the temperature of different target regions in the sample cooling cavity 3 to be able to be maintained at the second preset temperature more uniformly. Especially for the sample cooling cavity 3 with a certain length, temperature control of the sample cooling holder 9 can further improve the temperature control accuracy of different regions in the sample cooling cavity 3.

[0068] Specifically, the closed-loop cryogenic control system comprises a flow control module 5 for controlling the opening and closing of each pipeline in the closed-loop cryogenic control system, which can be used for pipeline cleaning of the pipelines in the closed-loop cryogenic control system before the refrigeration module 11 is controlled to start performing the cooling step, and can also be used for controlling the pipelines in the closed-loop cryogenic control system to be isolated from the outside and form a closed-loop pipeline during the cooling step performed by the temperature control device 1.

[0069] Specifically, the flow control module 5 comprises a first communication valve 51, a second communication valve 55, a pressure reducing valve 57, a gas release valve 54 and a circulating pump 53. The first communication valve 51 is arranged in the gas inlet pipeline 7 of the temperature control device 1 and is used to control the opening and closing of the gas inlet pipeline 7. The gas inlet pipeline 7 is in communication with the target gas storage module 6 and the gas inlet of the temperature control device 1 respectively 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 in a safe and stable operating condition. The gas outlet of the sample cold cavity 3, the circulating pump 53, the second communication valve 55 and the gas inlet of the temperature control device 1 are sequentially connected in pipeline to form a backflow pipeline 4. The gas release valve 54 is arranged between the second communication valve 55 and the circulating pump 53, one end of which is in communication with the backflow pipeline 4, and the other end is in communication with the outside. The buffer unit 56 is arranged in the backflow pipeline 4 and is in communication between the gas inlet pipeline 7 and the circulating pipeline.

[0070] Specifically, as shown in Figure 2 between the gas outlet of the temperature control device 1 and the gas inlet of the sample cold cavity 3, the delivery pipeline 2 and a section of the backflow pipeline 4 at the outlet end of the sample cold cavity 3 are in an inner-outer nested structure. The delivery pipeline 2 is coaxially arranged in the section of the backflow pipeline 4, and the section of the backflow pipeline 4 is an annular pipeline wrapped outside the delivery pipeline 2, i.e. the inner wall of the section of the backflow pipeline 4 is reused as the outer wall of the delivery pipeline 2, which can isolate the outer wall of the delivery pipeline 2 from the outside atmosphere to a certain extent, further reduce the loss of cold energy of the refrigeration gas during the delivery process in the delivery pipeline 2, improve the refrigeration power of the refrigeration gas delivered to the sample cold cavity 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 wrapped outside the refrigeration inner cavity, and the sample cold cavity 3 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 comprises a vacuum control module 8, the vacuum control module 8 comprises a first vacuum valve 81, a second vacuum valve 82 and a vacuum pump 83, the vacuum pump 83 is in on-off communication with the refrigeration outer cavity through the first vacuum valve 81, and the vacuum pump 83 is in on-off communication with the sample outer cavity through the second vacuum valve 82, so as to control the refrigeration inner cavity and the sample inner cavity to form a vacuum environment with the outside atmosphere respectively, play a heat insulation role, further reduce the heat exchange between the refrigeration inner cavity and the sample inner cavity and the outside atmosphere respectively, and be beneficial to maintaining the stability of the temperature in the refrigeration inner cavity and the sample inner cavity and saving energy.

[0072] Specifically, a plurality of monitoring elements are arranged in the closed-loop low-temperature control system, the plurality of monitoring elements comprise temperature monitoring elements, pressure monitoring elements 58 and flow monitoring elements 52, so as to display the state of the closed-loop low-temperature control system at the current time, and provide a reference for monitoring personnel to understand the running state of the current closed-loop low-temperature control system; for example, the temperature control device 1 is provided with at least two temperature monitoring elements, and the at least two temperature monitoring elements are located in different regions of the temperature control device 1, and one of the temperature monitoring elements is arranged at the first heating module, so as to monitor the temperature of the refrigeration gas at the first heating module.

[0073] In addition, it should be noted that some monitoring elements in the closed-loop low-temperature control system are affected by the pressure in the pipeline, and there is a deviation between the display value of the monitoring element and the actual value in the current system under different pressures, for example, the temperature monitoring element displays the current temperature value, but the temperature value is the temperature monitored by the temperature monitoring element under the calibration pressure, and 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 value; the closed-loop low-temperature control method is to adjust the set values of the plurality of control parameters in the system, so that the control parameters in the system are more accurate and reliable, and the stability of the system operation is improved.

[0074] The closed-loop low-temperature control method of the embodiment of the application will be described in detail below, and the accompanying drawings of the specification Figure 3 The method comprises:

[0075] S101, in the case that the sample cold cavity is in the refrigeration mode, acquiring the current temperature and the current target flow of the refrigeration gas currently conveyed into the conveying pipeline by the temperature control device.

[0076] The sample cold cavity in the refrigeration mode refers to a state in which the refrigeration module in the temperature control device has been started, the refrigeration gas has been transported in the conveying pipeline for a certain time, and the target gas after temperature rise has been backflowed in the backflow pipeline for a certain time. At this time, the gas outlet of the temperature control device, the conveying pipeline, and the sample cold cavity in the closed cycle low-temperature control system are already in a relatively low-temperature environment.

[0077] The first preset temperature refers to the temperature target value of the refrigeration gas input into the conveying pipeline by the temperature control device, that is, the temperature setting value required to be reached by the refrigeration gas. The first preset temperature can be set according to actual conditions. The first preset temperature can be a specific value, for example, the first preset temperature can be 4.5K, or a value range, for example, the first preset temperature can be 4.2-4.9K. The application does not make specific limitations.

[0078] Alternatively, the first preset temperature can be pre-configured by the control device or obtained by the control device. For example, when the 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 the subsequent control steps. At this time, the first preset temperature can be adjusted to meet various temperature control scenes and temperature control requirements, and has a wide range of applications.

[0079] The current target flow rate refers to the current flow rate setting value of the target gas in the backflow pipeline. The current target flow rate can be dynamically updated as the control process proceeds, that is, the flow rate setting value is adjustable. The current target flow rate can be a specific value, for example, the current target flow rate can be 6L / min, or a value range, for example, the current target flow rate can be 11.5-12L / min. The application does not make specific limitations.

[0080] In an optional embodiment, the backflow pipeline is provided with a flow control element. The maximum flow rate setting value of the flow control element is adjusted by the control device, which can limit the maximum flow rate of the target gas flowing through the flow control element, so that the flow rate of the target gas is maintained within the maximum flow rate setting value range. The current target flow rate is the maximum flow rate setting value currently set by the flow control element. The flow rate of the target gas in the backflow pipeline is controlled to reach and dynamically maintain within the maximum flow rate setting value range, which is convenient and accurate. In addition, the flow control element can also serve as a flow monitoring element, and the current target flow rate set by the flow control element is sent to the control device. The control device can quickly and accurately obtain the current target flow rate in the current backflow pipeline, so as to continue to execute subsequent steps such as S103, respond quickly, and control timely and accurately.

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

[0082] In the case that the sample cooling cavity is in the refrigeration mode, the refrigeration module has been started and continuously outputs cold energy, but the cold energy provided by the refrigeration module is also variable, for example, when the flow of the target gas flowing through the refrigeration module changes, the cold energy provided by the refrigeration module also changes, resulting in that the temperature of the refrigerant gas after passing through the refrigeration module is uncontrollable; in the embodiment, the refrigeration power of the refrigeration module is large, so that the refrigerant gas with different flow rates passing through the refrigeration module can be reduced to a temperature lower than the first preset temperature, and then the output power of the first heating module is adjusted to heat the refrigerant gas under the current target flow, so that the temperature of the refrigerant gas output from the outlet of the temperature control device after passing through the first heating module reaches the first preset temperature, realizing controllable and effective regulation and control of the temperature of the refrigerant gas, fast and accurate regulation and control, good regulation and control reliability, and effective maintenance of the stability of the temperature of the refrigerant gas.

[0083] It should be noted that the temperature of the refrigerant 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 of the first heating module is always used for heating, so that the temperature of the refrigerant 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, and in the case that the refrigeration module cannot accurately and effectively control the temperature of the refrigerant gas, the control of the temperature of the refrigerant gas by the entire temperature control device will also be out of control.

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

[0085] In some embodiments, the output power of the first heating module detected in this step is instantaneous power; in other embodiments, the output power of the first heating module detected in this step is the average power in 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; wherein the preset time interval is 2min-3min; it can be understood that the preset time interval can be any point value between 2min-3min, for example, the preset time interval can be 2min, 2.5min, 3min, etc., which can reserve enough time for the closed-loop low-temperature control system to reach a stable state, and avoid prolonging the cooling time and accelerating the cooling efficiency.

[0086] S107, in the case where the output power of the first heating module is higher than or equal to the power upper limit value, updating the current target flow rate by a preset increment to obtain an updated target flow rate.

[0087] In the case where the temperature of the refrigeration gas is the first preset temperature, the greater the flow rate of the refrigeration gas in the delivery pipeline, the greater the refrigeration power of the refrigeration gas delivered to the sample cold cavity; and the heat provided by the current target flow rate (the target gas after warming up itself carrying heat) and the heat provided by the output power of the first heating module are jointly neutralized with the uncontrollable cold output by the refrigeration module, when the current target flow rate increases, the target gas after warming 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, the target gas after warming 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 refrigeration gas delivered to the delivery pipeline by the temperature control device.

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

[0089] In the present embodiment, the power upper limit value refers to an output power threshold value below which the refrigeration power output to the sample cold cavity reaches a maximum (or the current target flow rate reaches a maximum flow rate set value) in the case where the temperature of the refrigeration 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 the power upper limit value, it indicates that the refrigeration power output to the sample cold cavity has not reached a maximum at this time, and the current target flow rate is updated by a preset increment to obtain an updated target flow rate, which is greater than the current target flow rate, so as to further reduce the output power of the first heating module.

[0090] The power upper limit value can be set in advance, which can be a specific numerical value, for example, the power upper limit value can be 0.5W, or a numerical range, for example, the power upper limit value can be 0.45-0.55W, which is not limited in the present application.

[0091] The preset increment is a variable setting value of the flow of the target gas in the return pipeline increased each time the current target flow is updated, and the sum of the preset increment and the current target flow is equal to the updated target flow; the preset increment can be set in advance, and the preset increment can be a specific value, for example, the preset increment can be 0.3 L / min, or a value range, for example, the preset increment can be 0.3-0.5 L / min, and the present application does not make specific limitation thereon; and in the process of repeatedly updating the step, the preset increment in the previous round of updating step can be the same as the preset increment in the next round of updating step, or can be different from the preset increment in the next round of updating step, and the control flexibility is good.

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

[0093] S109, based on the updated target flow, repeating the output power adjustment step of the first heating module to control the temperature of the refrigeration gas in the delivery pipeline to the first preset temperature.

[0094] If the flow setting value of the target gas in the return pipeline is directly increased to a larger target flow in the refrigeration mode, the temperature of the target gas is higher at this time, the load of the refrigeration module is too heavy, and for a large amount of target gas, the refrigeration module needs to provide greater refrigeration power and longer refrigeration time to reduce the temperature of the target gas to the first preset temperature; in this step, the output power adjustment step of the first heating module is repeated, that is, the steps S103-S107 are repeated, and the updated target flow is increased by a preset increment through multiple step-by-step updates, the refrigeration module can cool the target gas at a smaller target flow faster, and the temperature of the warmed 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 with the preset increment added in this updating step, thereby reducing the load of the refrigeration module, and after multiple repeated updating steps, the increased target gas can be gradually cooled, the overall refrigeration efficiency of the refrigeration module is accelerated, the energy consumption of the refrigeration module is saved, and the temperature of the refrigeration gas in the delivery pipeline is more easily and quickly reached to the first preset temperature.

[0095] In some embodiments, the control parameter in the closed-loop cryogenic control system changes over time during the actual operation of the closed-loop cryogenic control system, resulting in a change in the temperature of the refrigerant gas delivered to the delivery pipeline. In this case, the output power of the first heating module also needs to be monitored and updated dynamically during the entire operation process, and the target flow rate is updated dynamically and the output power of the first heating module is adjusted dynamically to maintain the temperature of the refrigerant gas delivered to the delivery pipeline at the first preset temperature and maintain the dynamic stability of the temperature.

[0096] Specifically, as shown in Figure 4 the method further comprises the following steps after monitoring 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 the first preset temperature, i.e., after the S105 step:

[0097] S111, in the case where the output power of the first heating module is lower than the upper limit value of the power, the current target flow rate is used as the expected flow rate, the return pipeline is controlled to return based on the current target flow rate, 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.

[0098] The expected flow rate refers to the maximum flow rate setting value of the target gas in the return pipeline after temperature rise when the temperature of the refrigerant 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 upper limit value of the power, and the refrigeration power delivered to the sample cold chamber reaches the maximum. The expected flow rate and the current output power of the first heating module are used as the steady-state operation of the closed-loop cryogenic control system, the cold energy loss in the delivery pipeline is extremely small, the temperature of the refrigerant gas reaching the sample cold chamber can be effectively controlled to be the first preset temperature, and the refrigeration efficiency is greatly improved.

[0099] In some preferred embodiments, the S111 step is performed after the S109 step, i.e., after the output power of the first heating module is adjusted multiple times, the output power of the first heating module is gradually adjusted to a state lower than the upper limit value of the power, and correspondingly, the updated target flow rate obtained after multiple updates of the preset increment reaches the maximum target flow rate that can be achieved when the temperature of the refrigerant gas in the delivery pipeline is the first preset temperature, i.e., the expected flow rate. Under the condition that the temperature of the refrigerant gas in the delivery pipeline is consistent, the greater the target flow rate, the greater the cold energy carried by the refrigerant gas, and the sample cold chamber can be better cooled and temperature maintained under the expected flow rate condition, and the stability and reliability of temperature control are good.

[0100] The whole control method can efficiently reduce the temperature of the refrigerant gas delivered by the temperature control device to the delivery pipeline in the closed-loop cryogenic control system to a first preset temperature, and make the flow of the refrigerant gas delivered to the sample cold cavity reach the desired flow quickly, with high cooling efficiency. Under the condition of the desired flow and the first preset temperature, the cooling capacity of the refrigerant gas in the delivery pipeline is reduced, the refrigeration power delivered to the sample cold cavity is maximized, and the temperature of the refrigerant gas in the sample cold cavity can be efficiently and accurately controlled.

[0101] Specifically, as shown in the case where the output power of the first heating module is lower than the upper limit value of the power, the current target flow is taken as the desired flow, and after the step S111, the method further comprises: Figure 5

[0102] S202, obtaining the current temperature of the refrigerant gas input into the sample cold cavity.

[0103] S204, taking the second preset temperature as the target temperature of the refrigerant gas input into the sample cold cavity, adjusting the output power of the second heating module according to the desired flow and the current temperature of the refrigerant gas input into the sample cold cavity, so that the temperature of the refrigerant gas input into the sample cold cavity reaches the second preset temperature, and the second preset temperature refers to the target value of the sample refrigeration temperature required by the refrigerant gas in the sample cold cavity.

[0104] Wherein, the second preset temperature is greater than the first preset temperature, so that the temperature of the refrigerant gas input into the sample cold cavity by the temperature control device is lower than the second preset temperature, thereby reserving the regulated space for the refrigerant gas delivered to the sample cold cavity, and avoiding 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 refrigerant gas in the sample cold cavity.

[0105] ​And, in the process of refrigeration gas being transported to the sample cold cavity through the delivery pipeline, the loss of cold in the delivery pipeline is reduced as much as possible by updating the current flow set value of the target gas in the return pipeline to the desired flow, but the refrigeration gas reaching the sample cold cavity can still have a slight temperature rise, so that the current temperature of the refrigeration gas input into the sample cold cavity deviates from the first preset temperature, and the temperature of the refrigeration gas reaching the sample cold cavity at different times can also be different, and the refrigeration gas input into the sample cold cavity is heated by adjusting the output power of the second heating module, so that the temperature of the refrigeration gas in the sample cold cavity is fine-tuned, and the temperature of the refrigeration gas input into the sample cold cavity reaches the second preset temperature, further improving the accuracy and stability of temperature control in the sample cold cavity.

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

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

[0108] Obtaining the current temperature of the refrigeration gas input into the sample cold cavity.

[0109] Taking the cold holder preset temperature as the target temperature of the refrigeration gas input into the sample cold cavity, adjusting the output power of the third heating module according to the desired flow and the current temperature of the refrigeration gas input into the sample cold cavity, so that the temperature of the refrigeration gas input into the sample cold cavity reaches the cold holder preset temperature, and the cold holder preset temperature refers to the target value of the sample refrigeration temperature required by the refrigeration gas in the sample cold cavity.

[0110] Specifically, the above S101-S111 steps and S202-S204 steps are performed when the sample cold cavity is in the refrigeration mode, that is, the steps of formal refrigeration, and before formal refrigeration, the closed cycle low temperature control system is pre-cooled to further improve the cooling efficiency; then as Figure 6 As shown in the figure, before the case where the sample cold cavity is in the refrigeration mode, that is, before the S101 step, the method comprises:

[0111] S301, in response to the sample cold chamber refrigeration mode trigger event, control the refrigeration module to start, control the flow set value of the target gas in the reflux pipeline to be a preset pre-cooling flow.

[0112] Wherein, the sample cold chamber refrigeration mode can be triggered by the control device to obtain the refrigeration mode trigger instruction input to the control device, or can be automatically triggered after a preset time interval after pipeline cleaning or vacuumizing the closed cycle low temperature control system. At this time, the refrigeration module starts to output cold energy, and the flow set value of the target gas in the reflux pipeline is set to the preset pre-cooling flow to make the system enter the refrigeration mode, and first pre-cool the pipeline.

[0113] The preset pre-cooling flow is the flow set value of the target gas in the reflux pipeline during the system pre-cooling process, which can be selected as a constant value to reduce the control difficulty of the pre-cooling process. In an optional embodiment, the preset pre-cooling flow is less than the current target flow in the formal refrigeration process in S101 step, and also less than the updated target flow in S105 step and the expected flow in S111 step, that is, the preset pre-cooling flow is the minimum flow set value of the target gas in the reflux pipeline in the entire closed cycle low temperature control process. The flow of the target gas is small, and under the condition that the cold energy output by the refrigeration module is the same, the target gas can be cooled to a very low temperature more quickly, so that the cold energy output by the refrigeration module can more efficiently cool the target gas under the preset pre-cooling flow, greatly improving the pre-cooling efficiency and shortening the pre-cooling time.

[0114] S303, in the state of refluxing the target gas based on the preset pre-cooling flow, taking the first preset temperature as the target temperature, adjusting the output power of the first heating module according to the temperature of the refrigeration gas in the conveying pipeline and the preset pre-cooling flow, until the output power of the first heating module reaches the power output steady state condition.

[0115] The power output steady state condition is that when the temperature of the refrigeration gas is maintained at the first preset temperature based on the preset pre-cooling flow rate of the target gas, the output power of the first heating module no longer changes or reaches a dynamic stable state, which can be that the output power is maintained stable and unchanged or reaches a dynamic stable state within a preset time interval. 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, and the control device determines that the output power of the first heating module in the pre-cooling process reaches the power output steady state condition. In other exemplary embodiments, the difference between the output powers of the first heating module in two adjacent preset time intervals is less than a preset output power difference, i.e., dynamic stability, wherein 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] The output power of the first heating module in the pre-cooling process is adjusted by the following steps:

[0117] The return pipeline is controlled to return the target gas at the preset pre-cooling flow rate.

[0118] The first heating module is controlled to start.

[0119] The temperature control device monitors the temperature of the refrigeration gas input into the delivery pipeline.

[0120] The output power of the first heating module is adjusted according to the temperature of the refrigeration gas in the delivery pipeline and the preset pre-cooling flow rate.

[0121] S305, the output power that meets the output steady state condition is determined as the target pre-cooling power, and the first heating module is controlled to operate at the target pre-cooling power.

[0122] In the pre-cooling process, the preset pre-cooling flow rate is the minimum flow rate set value in the entire refrigeration process, and correspondingly, the target pre-cooling power that meets the power output steady state condition in the pre-cooling process is the maximum output power in the entire refrigeration process when the temperature of the refrigeration gas is controlled to be the first preset temperature.

[0123] In this step, the return pipeline returns the target gas at the preset pre-cooling flow rate, and the first heating module operates at the target pre-cooling power for a preset pre-cooling time, and the pre-cooling process in the system is completed. The preset pre-cooling time can be set according to actual conditions, which is not limited in the present application.

[0124] S307, the flow rate set value in the return pipeline is updated from the preset pre-cooling flow rate to a target flow rate.

[0125] After the preset pre-cooling time, the system has been in a relatively low temperature state, and the flow rate set value in the return pipeline is updated to the target flow rate to increase the target flow rate, which is the current target flow rate in the S101 step, so that the closed-loop low-temperature control system enters the formal refrigeration state, and the refrigeration power of the refrigeration gas input into the sample cold cavity is improved.

[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 shown in the figure, before the control of the refrigeration module is started, that is, before the S301 step, the method further comprises: Figure 7

[0127] S402, in response to the refrigeration mode trigger event of the sample cold cavity, the first communication valve is controlled to be opened to deliver the target gas to the temperature control device.

[0128] S404, in the state of detecting that the target gas flows in the return pipeline, the circulation pump and the gas exhaust valve are controlled to be opened, and the second communication valve is controlled to be closed to perform pipeline cleaning.

[0129] S406, in the case where it is detected that the cleaning time reaches the preset cleaning time, the gas exhaust valve is controlled to be closed and the second communication valve is controlled to be opened, and the flow rate set value of the target gas in the return pipeline is controlled to be a preset cleaning flow rate to trigger the refrigeration module to start.

[0130] Through the steps S402-S404, the gas inlet pipeline, the delivery pipeline and the return pipeline are filled with target gas, and the gas originally existing in the above pipelines is removed from the pipeline to the outside atmosphere through the gas exhaust valve; wherein, the S404 step lasts for a preset cleaning time to replace the gas in the pipeline with the target gas as much as possible, and then in the case where it is detected that the cleaning time reaches the preset cleaning time, the S406 step is performed, the gas exhaust valve is closed to isolate the pipeline of the closed-loop low-temperature control system from the outside atmosphere, the second communication valve is opened to form a closed-loop pipeline that communicates the gas inlet pipeline, the delivery pipeline and the return pipeline, and the flow rate value of the target gas in the return pipeline is controlled to be a preset cleaning flow rate, so that the pipeline in the closed-loop low-temperature control system always maintains the atmosphere of the target gas, the cleaning efficiency is high, and the stability of the target gas atmosphere in the system is good.

[0131] ​In some embodiments, the preset cleaning time length is 10-20 minutes. Understandably, the preset cleaning time length can be any point value in the range of 10-20 minutes, for example, the preset cleaning time length can be 10 minutes, 11 minutes, 12 minutes, 15 minutes, 20 minutes, etc., on the one hand, so that the target gas can be fully cleaned, and on the other hand, the waste of the target gas is avoided, and the cost is saved.

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

[0133] Specifically, before the step of controlling the circulation pump and the gas exhaust valve to be opened and the second communication valve to be closed to clean the pipeline, i.e., before the step S404, the method further comprises:

[0134] controlling the pressure reducing valve to be opened;

[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, so that the pressure in the gas inlet pipeline reaches the preset pressure.

[0137] The preset pressure is a pressure setting value for maintaining the safe operation of the closed-loop cryogenic control system, which is close to the atmospheric pressure. In some optional embodiments, the preset pressure is 0-0.1 bar, which maintains a weak pressure difference between the two sides of the pressure reducing valve, so that a large amount of hot gas does not rush into the refrigeration cavity when the gas filling valve is opened. At the same time, it is also beneficial to maintain the safety of the closed-loop cryogenic control system as a whole and prolong the service life.

[0138] In some embodiments, the current pressure can be monitored by a pressure monitoring element, and the current pressure can be sent to the control device by the pressure monitoring element, so that the control device determines the difference between the current pressure and the preset pressure to adjust the opening degree of the pressure reducing valve, which has 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, for example, a differential pressure gauge, and the pressure detection element can directly send the pressure difference to the control device, so that the control device directly adjusts the opening degree of the pressure reducing valve according to the pressure difference, which has fast response and timely control.

[0139] Specifically, as Figure 8As shown, before the control of the start of the refrigeration module, i.e. before the step S301, the method further comprises:

[0140] S501, 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, so as to respectively vacuumize the refrigeration outer cavity and the sample outer cavity to meet the vacuum condition of the refrigeration outer cavity and the sample outer cavity.

[0141] This step is performed before cooling, especially before pre-cooling, i.e. pre-vacuumizing 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 external atmosphere, which can effectively isolate heat exchange, reduce the loss of cold energy in the refrigeration inner cavity and the sample inner cavity, and greatly improve the temperature stability; the pre-vacuumizing process can be performed before or after the pipeline cleaning process, or simultaneously, and the operation of the two does not interfere with each other, which can further save the operation efficiency of the closed-cycle low-temperature control system and save time cost.

[0142] Specifically, as shown in the figure, Figure 8 The method further comprises:

[0143] S503, in response to a temperature rising 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.

[0144] The temperature rising mode of the sample cold cavity can be triggered by a sample replacement event of the sample cold cavity, the control device obtains a sample replacement instruction input into the control device, so as to determine that the sample cold cavity enters the temperature rising mode; or the temperature rising mode can be automatically triggered after a certain time in the step S111, i.e. the temperature rising mode is triggered after the sample detection in the sample cold cavity is completed.

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

[0146] S505, in response to a switching event from the temperature rising 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.

[0147] After entering the heating mode, the control device controls the vacuum pump to stop pumping, the first vacuum valve to close, and the refrigeration inner cavity to be in a vacuum state all the time, so that when switching back to the refrigeration mode, the refrigeration outer cavity does not need to be pumped again, thereby saving energy; and the second vacuum valve is closed, and the sample outer cavity is in communication with the atmosphere when the sample cold cavity is replaced, so that when switching back to the refrigeration mode, the vacuum pump and the second vacuum valve are controlled to be opened to re-pump 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 a switching event from the heating mode to the refrigeration mode, the first vacuum valve, the second vacuum valve, and the vacuum pump are controlled to be opened to re-pump the refrigeration outer cavity and the sample outer cavity.

[0149] Specifically, when all samples in the sample cold cavity are detected or the sample in the sample cold cavity needs to be replaced, a heating demand occurs to facilitate sampling. Figure 9 As shown, after the step of controlling the return pipeline to return based on the current target flow 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 the S111 step, the method further comprises:

[0150] S602, in response to a heating mode triggering event, adjusting a flow set value of the target gas in the return pipeline to a preset heating flow, and controlling the refrigeration module to be closed.

[0151] The preset heating flow is greater than the expected flow, so that the target gas in the return pipeline circulates at a larger flow, accelerates the heating speed of the pipeline in the closed-loop low-temperature control system, and shortens the heating time; in an optional embodiment, the preset heating flow is set to a constant value, which does not need to be adjusted after being set, thereby reducing the control load of the control device; in some optional embodiments, the preset heating flow can be equal to the preset cleaning flow, both of which are larger flow set values, for example, the preset heating flow and the preset cleaning flow are both 12 L / min, which is simple and convenient to control and has high heating efficiency.

[0152] S604, taking a third preset temperature as a target temperature of the refrigeration gas in the delivery pipeline, adjusting the heating power of the first heating module according to the preset heating flow 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 a fourth preset temperature as a target temperature of the refrigeration gas input into the sample cold cavity, adjusting the heating power of the second heating module according to the preset heating flow and the current temperature of the refrigeration gas input into the sample cold cavity, until the temperature of the refrigeration gas in the sample cold cavity reaches the fourth preset temperature.

[0154] The S604 step and the S606 step are executed in parallel respectively, and there is no sequence between the two; wherein the third preset temperature is a temperature setting value required to be reached by the temperature control device after heating, and the fourth preset temperature is a temperature setting value required to be reached by the sample cold cavity after heating.

[0155] Before heating, the sample cold cavity is still in a low-temperature environment, and when sampling or closing the system, it needs to be heated 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 in 277K-293K, for example, the third preset temperature can be 277K, 282K, 285K, 287K, 293K, etc., to prevent dewing and other phenomena; 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 process, the temperature rises quickly in the early stage of heating, slowly in the later stage of heating, and the heat insulation effect of the vacuum environment disappears, the temperature setting value is close to the ambient temperature, which can reduce the heat exchange between the target gas in the temperature control device and the sample cold cavity and the air at room temperature, prevent the temperature in the sample cold cavity from being difficult to reach the third preset temperature, and at the same time, prevent the third preset temperature from being too high, which leads to a very slow heating speed in the later stage and wastes a lot of heating time, thereby improving the heating efficiency.

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

[0157] When each temperature in the closed-loop low-temperature control system reaches the corresponding preset temperature, the first heating module, the second heating module and the vacuum control module are controlled to close, so that the closed-loop low-temperature control system as a whole stops running.

[0158] Specifically, in some optional embodiments, before the S608 step, the method further comprises:

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

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

[0161] In the case where the current pressure is monitored to be higher than the preset safety pressure, the vent valve is controlled to open until the pressure in the gas inlet pipeline is lower than the preset safety pressure.

[0162] The preset safety pressure is an upper limit pressure setting value that the pipeline in the closed cycle low-temperature control system can bear to maintain the safety of the closed cycle low-temperature control system. In an optional embodiment, the preset safety pressure is equal to the preset pressure, and the safety is good.

[0163] During the temperature rising process, the pressure of the target gas rises, and the preset temperature rising flow rate is large, so the flow rate of the target gas in the reflux pipeline is also large, which can also cause the pressure in the pipeline to rise, and has a potential risk of endangering the safety of the pipeline. Therefore, when it is monitored that the current pressure is higher than the preset safety pressure, the vent valve is controlled to be opened to release pressure and reduce the risk of explosion of the pipeline.

[0164] In some embodiments, at least one safety valve is further provided in the closed cycle low-temperature control system, and the safety valve can be automatically opened and closed. When the current pressure in the pipeline reaches a pressure critical value that the safety valve can bear, the safety valve is opened under the action of the 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 is reduced to a lower limit pressure value that can open the safety valve, the safety valve is automatically closed, which greatly improves the safety of the system.

[0165] The following introduces a specific process of a closed cycle low-temperature control method in a specific embodiment, as shown in Figure 10 and Figure 11 The values of the various control parameters are only examples and do not limit the present application.

[0166] S1, in response to a refrigeration mode triggering event of a sample cold cavity, the first communication valve is controlled to be opened to deliver the target gas to the temperature control device.

[0167] S2, the pressure reducing valve is controlled to be opened.

[0168] S3, the current pressure in the gas inlet pipeline is monitored by the pressure monitoring element.

[0169] S4, the opening degree 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 0-0.1 bar.

[0170] S5, it is judged whether the pressure in the gas inlet pipeline reaches the preset pressure 0-0.1 bar.

[0171] S6, if the pressure in the gas inlet pipeline reaches 0-0.1 bar, the circulation pump and the vent valve are controlled to be opened, and the second communication valve is controlled to be closed, to perform pipeline cleaning, under the condition that the target gas is detected to flow in the reflux pipeline.

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

[0173] S7, in the case of detecting that the cleaning duration reaches 10 minutes, controlling the closing of the exhaust valve and the opening of the second communication valve, and controlling the flow set value of the target gas in the reflux pipeline to be 12 L / min, so as to trigger the starting of the refrigeration module.

[0174] S8, in response to the refrigeration mode trigger event of the sample cold cavity, controlling the opening of the first vacuum valve, the second vacuum valve and the vacuum pump, so as to respectively vacuumize the refrigeration outer cavity and the sample outer cavity to meet the vacuum condition of the refrigeration outer cavity and the sample outer cavity.

[0175] S9, judging whether the temperature rise mode trigger event of the sample cold cavity occurs.

[0176] S10, if the temperature rise mode trigger event of the sample cold cavity occurs, in response to the temperature rise mode trigger event of the sample cold cavity, if the first vacuum valve, the second vacuum valve and the vacuum pump are in the open state, controlling the closing of the first vacuum valve, the second vacuum valve and the vacuum pump.

[0177] Otherwise, returning to the step S8 to maintain the refrigeration outer cavity and the sample outer cavity to meet the vacuum condition.

[0178] S11, judging whether the switching event from the temperature rise mode to the refrigeration mode occurs.

[0179] S12, if the switching event from the temperature rise mode to the refrigeration mode occurs, in response to the switching event from the temperature rise 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, controlling the opening of the second vacuum valve and the vacuum pump.

[0180] Otherwise, returning to the 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 cavity, controlling the starting of the refrigeration module and controlling the preset pre-cooling flow of the target gas in the reflux pipeline to be 6 L / min.

[0182] S14, controlling the reflux pipeline to reflux the target gas at the preset pre-cooling flow.

[0183] S15, controlling the starting of the first heating module.

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

[0185] S17, in the state of refluxing the target gas based on the preset pre-cooling flow, taking 4.5 K as the target temperature, adjusting the output power of the first heating module according to the temperature of the refrigeration gas in the conveying pipeline and the preset pre-cooling flow, until the output power of the first heating module reaches the target pre-cooling power and is maintained for 3 minutes and above, so as to meet the power output steady state condition.

[0186] S18, determining whether the output power of the first heating module reaches the target pre-cooling power and maintaining for 3 minutes or more.

[0187] S19, if the determination result is yes, determining the output power meeting 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 target pre-cooling power is the maximum output power of the first heating module in the entire adjustment process.

[0188] Otherwise, return to step S17.

[0189] S20, updating the flow set value in the return line from the preset pre-cooling flow increment to the target flow.

[0190] S21, in the case that the sample cooling cavity is in the refrigeration mode, obtaining the current temperature of the refrigeration gas currently delivered by the temperature control device into the delivery line and the current target flow.

[0191] S22, adjusting the output power of the first heating module according to the current temperature of the refrigeration gas in the delivery line, the first preset temperature 4.5K and the current target flow, so that the temperature of the refrigeration gas in the delivery line reaches 4.5K.

[0192] S23, monitoring the output power of the first heating module in the process of controlling the temperature of the refrigeration gas in the delivery line to be 4.5K.

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

[0194] S25, in the case that the output power of the first heating module is higher than or equal to 0.5W, updating the current target flow by a preset increment 0.3L / min to obtain an updated target flow.

[0195] S26, repeating the above output power adjustment step of the first heating module based on the updated target flow to control the temperature of the refrigeration gas in the delivery line to be 4.5K.

[0196] S27, in the case that the output power of the first heating module is lower than 0.5W, taking the current target flow as the expected flow, and controlling the return line to return based on the current target flow 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.

[0197] S28, obtaining the current temperature of the refrigeration gas input into the sample cooling cavity.

[0198] S29, taking the second preset temperature as a target temperature of the refrigerant gas input into the sample cold chamber, adjusting the output power of the second heating module according to the expected flow 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.

[0199] S30, obtaining the current temperature of the refrigerant gas input into the sample cold holder.

[0200] S31, taking the cold holder preset temperature as a target temperature of the refrigerant gas input into the sample cold holder, adjusting the output power of the third heating module according to the expected flow and the current temperature of the refrigerant gas input into the sample cold holder, until the temperature of the refrigerant gas input into the sample cold holder reaches the cold holder preset temperature.

[0201] S32, in response to a warming-up mode triggering event, adjusting the flow set value of the target gas in the return pipeline to a preset warming-up flow, and controlling the refrigeration module to be closed.

[0202] S33, taking the third preset temperature as a target temperature of the refrigerant gas in the delivery pipeline, adjusting the heating power of the first heating module according to the preset warming-up flow 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.

[0203] S34, taking the fourth preset temperature as a 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 warming-up flow 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.

[0204] S35, monitoring the current pressure in the gas inlet pipeline.

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

[0206] S37, in the case of monitoring that the current pressure is higher than the preset safety pressure, controlling the gas release valve to be opened until the pressure in the gas inlet pipeline is lower than the preset safety pressure.

[0207] S38, in the case of monitoring that the current pressure is lower than the preset safety pressure, judging whether the temperature of the refrigerant gas in the delivery pipeline reaches the third preset temperature, and judging whether the temperature of the refrigerant gas in the sample cold chamber reaches the fourth preset temperature.

[0208] S39, if the temperature of the refrigerant gas in the delivery pipeline reaches the third preset temperature, and the temperature of the refrigerant gas in the sample cold chamber reaches the fourth preset temperature, controlling the first heating module, the second heating module and the vacuum control module to be closed.

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

[0210] It can be seen from the above embodiments that the closed-loop low-temperature control method in the embodiments has the following beneficial effects:

[0211] The closed-loop low-temperature control method in the embodiments of the present application has the following beneficial effects:

[0212] Corresponding to the closed-loop low-temperature control method provided by the above embodiments of the present application, the control device in the closed-loop low-temperature control system provided by the embodiments of the present application can implement the closed-loop low-temperature control method in the above method embodiments, and the control device can include:

[0213] The acquisition module is configured to, in a case where the sample cold cavity is in a refrigeration mode, acquire a current temperature and a current target flow rate of refrigeration gas currently delivered by the temperature control device into the delivery pipeline, the first preset temperature being a temperature target value of refrigeration gas input by the temperature control device into the delivery pipeline, and the current target flow rate being a current flow rate setting value of target gas in the return pipeline.

[0214] The power adjustment module is configured to adjust the output power of the first heating module according to the current temperature of refrigeration gas in the delivery pipeline, the first preset temperature, and the current target flow rate, so that the temperature of refrigeration gas in the delivery pipeline reaches the first preset temperature.

[0215] The monitoring module is configured to monitor the output power of the first heating module in a process of controlling the temperature of refrigeration gas in the delivery pipeline to be the first preset temperature.

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

[0217] a circulating module configured to repeat the output power adjustment of the first heating module based on the updated target flow to control the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature.

[0218] It should be noted that the control device provided in the above embodiments is only taken as an example for the division of the above functional modules in realizing its functions, and in actual applications, the above functions can be completed by 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 above described functions. In addition, the control device and method embodiments provided in the above embodiments belong to the same concept, and the specific implementation process is detailed in the method embodiments, which will not be described here.

[0219] The closed-loop low-temperature control system is controlled by a control device, which includes a processor and a memory. The processor (or CPU (Central Processing Unit)) is the core component of the control device, and its main functions are to interpret memory instructions and process data feedback from various modules. The structure of the processor is roughly divided into arithmetic logic units and register units. The arithmetic logic unit mainly performs related logical calculations (such as shift operations, logical operations, fixed-point or floating-point arithmetic operations, and address operations). The register unit is used to temporarily store instructions, data, and addresses.

[0220] The memory is a memory device that can be used to store software programs and modules. The processor performs 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. The program storage area can store an operating system, which can include but is not limited to Windows (an operating system) and Linux (an operating system). The application does not limit this. In addition, it can also store application programs required for functions, etc. 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. These instructions can be one or more computer programs (including program code). The data storage area can store data created according to the use of the device. Accordingly, the memory can also include a memory controller to provide the processor with access to the memory.

[0221] The embodiment of the present application further provides a storage medium, wherein at least one instruction or at least one program is stored in the storage medium, the at least one instruction or the at least one program is loaded and executed by a processor to realize the closed-loop low-temperature control method described above; optionally, the storage medium can be located in at least one network server in a plurality of network servers of a computer network; in addition, the storage medium can include but is not limited to random access memory (RAM), read-only memory (ROM), non-volatile memory (NVM), a U disk, a mobile hard disk, a disk storage device, a flash memory device, other volatile solid-state storage devices and various storage media capable of storing program codes.

[0222] It should be noted that the above-mentioned embodiment sequence of the present application is only for description, not representing the advantages and disadvantages of the embodiments. And the above-mentioned embodiment of the present application is described. Other embodiments are within the scope of the appended claims. In some cases, the actions or steps recorded in the claims can be executed in an order different from that in the embodiments and still achieve the desired results. In addition, the processes depicted in the drawings do not necessarily require the specific order or continuous order shown to achieve the desired results. In some embodiments, multi-task processing and parallel processing are possible or can be advantageous.

[0223] Each embodiment in the specification is described in a progressive manner, and the same or similar parts between each embodiment can be referred to each other, and each embodiment mainly explains the difference from other embodiments. Especially, for the device embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts can be referred to the part of the method embodiment.

[0224] The above description is only some embodiments of the present application, and is not used to limit the present application. It should be appreciated by those skilled in the art that the present application can have various changes and improvements. Any modification, equivalent replacement and improvement made according to the present application all fall within the scope of the present application.

Claims

1. A closed cycle cryogenic control method applied to a closed cycle cryogenic control system, characterized by, The closed-loop low-temperature control system comprises a temperature control device, a conveying pipeline, a return pipeline and a flow control module, a gas outlet of the temperature control device, the conveying pipeline, a sample cooling cavity, the return pipeline and a gas inlet of the temperature control device are sequentially communicated, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used for cooling target gas passing through the temperature control device to form refrigeration gas conveyed to the conveying pipeline, and the first heating module is used for heating the refrigeration gas so that the refrigeration gas reaches a first preset temperature; the return pipeline is used for conveying the target gas warmed in the sample cooling cavity back to the temperature control device; the flow control module comprises a first communication valve, a second communication valve, a gas discharge valve and a circulating pump, the first communication valve is arranged in a gas inlet pipeline of the temperature control device; a gas outlet of the sample cooling cavity, the circulating pump, the second communication valve and the gas inlet of the temperature control device are sequentially connected by pipelines to form the return pipeline, and the gas discharge valve is arranged between the second communication valve and the circulating pump, one end of the gas discharge valve is communicated with the return pipeline, and the other end of the gas discharge valve is communicated with the outside; The method comprises: in response to a refrigeration mode triggering event of the sample cooling cavity, controlling the first communication valve to open to convey the target gas to the temperature control device; in a state of detecting that the target gas flows in the return pipeline, controlling the circulating pump and the gas discharge valve to open, and controlling the second communication valve to close to perform pipeline cleaning; in a case where it is detected that a cleaning duration reaches a preset cleaning duration, controlling the gas discharge valve to close and the second communication valve to open, and controlling a flow set value of the target gas in the return pipeline to be a preset cleaning flow to trigger the refrigeration module to start; controlling the flow set value of the target gas in the return pipeline to be a preset precooling flow; in a state of returning the target gas based on the preset precooling flow, taking the first preset temperature as a target temperature, adjusting an output power of the first heating module according to a temperature of the refrigeration gas in the conveying pipeline and the preset precooling flow, until the output power of the first heating module reaches a power output steady state condition; determining the output power meeting the output steady state condition as a target precooling power, and controlling the first heating module to operate at the target precooling power; incrementally updating the flow set value in the return pipeline from the preset precooling flow to a target flow; in a case where the sample cooling cavity is in a refrigeration mode, acquiring a current temperature of refrigeration gas currently conveyed by the temperature control device to the conveying pipeline and a current target flow, the first preset temperature refers to a temperature target value of refrigeration gas input by the temperature control device to the conveying pipeline, and the current target flow refers to a current flow set 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 refrigeration gas in the conveying pipeline, the first preset temperature and the current target flow, until the temperature of the refrigeration gas in the conveying pipeline reaches the first preset temperature. monitoring the output power of the first heating module in the process of controlling the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature; in the case where the output power of the first heating module is monitored to be higher than or equal to the upper limit value of power, updating the current target flow rate by a preset increment to obtain an updated target flow rate; repeating the output power adjustment 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.

2. The closed cycle cryogenic control method of claim 1, wherein, After the step of monitoring the output power of the first heating module in the process of controlling the temperature of the refrigerant gas in the delivery pipeline to be the first preset temperature, the method further comprises: in the case where the output power of the first heating module is monitored to be lower than the upper limit value of power, taking the current target flow rate as a 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, and repeating the step of monitoring the output power of the first heating module.

3. The closed cycle cryogenic control method of claim 2, wherein, The closed-loop cryogenic control system further comprises a second heating module for heating the refrigerant gas input into the sample cold cavity to reach a second preset temperature; after the step of, in the case where the output power of the first heating module is monitored to be lower than the upper limit value of power, taking the current target flow rate as a 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, the method further comprises: obtaining the current temperature of the refrigerant gas input into the sample cold cavity; taking the second preset temperature as a target temperature of the refrigerant gas input into the sample cold cavity, adjusting the output power of the second heating module according to the desired flow rate and the current temperature of the refrigerant gas input into the sample cold cavity, so that the temperature of the refrigerant gas input into the sample cold cavity reaches the second preset temperature, and the second preset temperature refers to a target value of a sample refrigeration temperature required to be reached by the refrigerant gas in the sample cold cavity.

4. The closed cycle cryogenic control method of claim 1, wherein, The flow control module further comprises a pressure reducing valve arranged in the gas inlet pipeline; before the step of, in the case where the state that the target gas flows in the return pipeline is detected, controlling the circulating pump and the gas discharge valve to be opened, and controlling the second communication valve to be closed, to perform pipeline cleaning, the method further comprises: controlling the pressure reducing valve to be opened; monitoring the current pressure in the gas inlet pipeline; adjusting the opening degree of the pressure reducing valve according to the difference between the current pressure in the gas inlet pipeline and a preset pressure, so that the pressure in the gas inlet pipeline reaches the preset pressure.

5. The closed cycle cryogenic control method of claim 3, wherein, 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 a sample and a sample outer cavity wrapped outside the sample inner cavity, the closed cycle low temperature control system comprises a vacuum control module, the vacuum control module comprises a first vacuum valve, a second vacuum valve and a vacuum pump, the vacuum pump is in on-off communication with the refrigeration outer cavity through the first vacuum valve, and the vacuum pump is in on-off communication with the sample outer cavity through the second vacuum valve; before the control of starting of the refrigeration module, the method further comprises: In response to a refrigeration mode trigger event of the sample cold cavity, the first vacuum valve, the second vacuum valve and the vacuum pump are controlled to be opened to respectively vacuumize the refrigeration outer cavity and the sample outer cavity, so that the refrigeration outer cavity and the sample outer cavity satisfy a vacuum condition.

6. The closed cycle cryogenic control method of claim 5, wherein, The method further comprises: In response to a temperature rising mode trigger event of the sample cold cavity, if the first vacuum valve, the second vacuum valve and the vacuum pump are in an open state, the first vacuum valve, the second vacuum valve and the vacuum pump are controlled to be closed; In response to a switching event from the temperature rising 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, the second vacuum valve and the vacuum pump are controlled to be opened.

7. The closed cycle cryogenic control method of claim 5, wherein, After the control of the return pipeline to return based on the current target flow and the control of the first heating module to operate at the current output power of the first heating module, and the repetition of the step of monitoring the output power of the first heating module, the method further comprises: In response to a temperature rising mode trigger event, the flow setting value of the target gas in the return pipeline is adjusted to a preset temperature rising flow, and the refrigeration module is controlled to be closed; A third preset temperature is taken as a target temperature of refrigeration gas in the conveying pipeline, the heating power of the first heating module is adjusted according to the preset temperature rising flow and the current temperature of the refrigeration gas in the conveying pipeline, so that the temperature of the refrigeration gas in the conveying pipeline reaches the third preset temperature; A fourth preset temperature is taken as a target temperature of refrigeration gas input into the sample cold cavity, the heating power of the second heating module is adjusted according to the preset temperature rising flow and the current temperature of the refrigeration gas input into the sample cold cavity, so that the temperature of the refrigeration gas in the sample cold cavity reaches the fourth preset temperature; The first heating module, the second heating module and the vacuum control module are controlled to be closed.

8. A closed cycle cryogenic control system characterized by, The closed-loop low-temperature control method according to any one of claims 1-7 is used for temperature control, and the closed-loop low-temperature control system comprises a temperature control device, a delivery pipeline, a return pipeline and a control device, a gas outlet of the temperature control device, the delivery pipeline, a sample cooling cavity, the return pipeline and a gas inlet of the temperature control device are sequentially connected, the temperature control device comprises a refrigeration module and a first heating module, the refrigeration module is used for cooling target gas passing through the temperature control device to form refrigeration gas delivered to the delivery pipeline, and the first heating module is used for heating the refrigeration gas so that the refrigeration gas reaches a first preset temperature; and the return pipeline is used for delivering the target gas heated in the sample cooling cavity back to the temperature control device. The control device comprises: an acquisition module, configured to acquire a current temperature of refrigeration gas currently delivered by the temperature control device to the delivery pipeline and a current target flow rate in a case where the sample cooling cavity is in a refrigeration mode, the first preset temperature is a temperature target value of refrigeration gas input by the temperature control device to the delivery pipeline, and the current target flow rate is a current flow rate setting value of target gas in the return pipeline; a power adjustment module, configured to adjust output power of the first heating module according to the current temperature of refrigeration gas in the delivery pipeline, the first preset temperature and the current target flow rate, so that the temperature of refrigeration gas in the delivery pipeline reaches the first preset temperature; a monitoring module, configured to monitor the output power of the first heating module in a process of controlling the temperature of refrigeration gas in the delivery pipeline to be the 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 in a case where the output power of the first heating module is higher than or equal to a power upper limit value; and a circulation module, configured to repeat the output power adjustment of the first heating module based on the updated target flow rate to control the temperature of refrigeration gas in the delivery pipeline to be the first preset temperature.

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