Control method of temperature control system, temperature control system and test equipment

Abstract

The application relates to a control method of a temperature regulating system, the temperature regulating system and test equipment, which comprises a primary refrigeration module, a secondary refrigeration module, a heat exchange module and a cooling circuit, the cooling circuit is thermally coupled with a primary refrigeration circuit of the primary condenser of the primary refrigeration module, the heat exchange module comprises a first heat exchanger, a heat exchange part, a heat exchange circuit and a circulating pump, the first heat exchanger is thermally coupled with the heat exchange circuit and the secondary refrigeration circuit, the heat exchange circuit is filled with a heat exchange medium, and the heat exchange part is thermally coupled with the heat exchange circuit and the cooling circuit. According to the technical scheme, the temperature of the back gas refrigerant can be adjusted when the load evaporator is overloaded or underloaded, the problems of overheating of the back gas of the compressor and overheating of the exhaust gas are solved, and the service life of the compressor is prolonged.

Description

Technical Field

[0001] This application relates to the field of refrigeration technology, and in particular to control methods, temperature control systems, and testing equipment for temperature control systems. Background Technology

[0002] The test sorting machine achieves a range of test temperatures through a refrigerant chiller and a heating system. In related technologies, testing is conducted by installing a standard test template at the load evaporator of the refrigerant chiller, and then the operating parameters of the refrigerant chiller are solidified, providing a correlation between different production temperatures and evaporation temperatures. In actual use, the contact thermal resistance between different chips and the load evaporator varies significantly, as does the heat exchange capacity with the test template. When the heat exchange capacity is stronger than the standard test template, the return gas heat exchange effect is good, but the evaporator return gas superheat is excessive, posing a risk of excessively high exhaust temperature for the refrigerant chiller. When the heat exchange capacity is weaker than the standard test template, the return gas heat exchange effect is poor, the production temperature cannot reach the target value, and the chiller is at risk of operating with liquid in the return gas, potentially leading to compressor oil shortage and cylinder seizure. Summary of the Invention

[0003] Based on this, this application provides a control method, a temperature control system, and a testing device for a temperature control system, which is used to protect the compressor and improve its service life when the cooling capacity of the temperature control system does not match the load demand.

[0004] In a first aspect, this application proposes a control method for a temperature control system. The temperature control system includes a primary refrigeration module, a secondary refrigeration module, a heat exchange module, and a cooling circuit. The primary refrigeration module includes a primary compressor, a primary condenser, a primary expansion valve, and an evaporator-condenser arranged sequentially in the primary refrigeration circuit. The cooling circuit is thermally coupled to the primary condenser. The secondary refrigeration module includes a secondary compressor, a secondary expansion valve, and a load evaporator arranged sequentially in the secondary refrigeration circuit. The primary and secondary refrigeration modules are thermally coupled through the evaporator-condenser. The heat exchange module includes a first heat exchanger, a heat exchange section, a heat exchange circuit, and a circulating pump. The circulating pump is located in the heat exchange circuit. The first heat exchanger thermally couples the heat exchange circuit and the secondary refrigeration circuit, and is arranged in the secondary refrigeration circuit between the load evaporator and the secondary compressor. The heat exchange circuit is filled with a heat exchange medium. The heat exchange section thermally couples the heat exchange circuit and the cooling circuit. The control method includes:

[0005] In cooling mode, the status data of the temperature control system is acquired, including the secondary return gas superheat and the secondary exhaust temperature of the secondary compressor.

[0006] Based on the status data, it is determined whether the temperature control system meets the overload condition or the low load condition. The overload condition is that the secondary return gas superheat exceeds the upper limit of the first return gas superheat and the secondary exhaust temperature exceeds the upper limit of the exhaust temperature. The low load condition is that the secondary return gas superheat is lower than the lower limit of the return gas superheat and the secondary exhaust temperature is lower than the lower limit of the exhaust temperature.

[0007] When the overload condition is met, the temperature control system is controlled to enter the overload control mode; in the overload control mode, the circulation pump is turned on so that the cooling circuit indirectly cools the return gas refrigerant of the secondary compressor through the heat exchange circuit.

[0008] When the low-load condition is met, the temperature control system is controlled to enter the low-load control mode; in the low-load control mode, the circulation pump is turned on so that the cooling circuit indirectly heats the return gas refrigerant of the secondary compressor through the heat exchange circuit.

[0009] In some embodiments, activating the circulation pump in the overload control mode includes:

[0010] In the overload control mode, the opening of the secondary expansion valve is first adjusted to gradually increase the evaporation temperature of the load evaporator until the first termination condition is met; when the first termination condition and the overload condition are met, the circulation pump is started.

[0011] In some embodiments, adjusting the opening of the secondary expansion valve to gradually increase the evaporation temperature of the loaded evaporator until a first termination condition is met includes:

[0012] The opening of the secondary expansion valve is adjusted at set intervals so that the evaporation temperature of the load evaporator rises to the set temperature each time.

[0013] After each adjustment, when the evaporation temperature of the load evaporator stabilizes for a set time, it is determined whether the temperature control system meets the first termination condition. The first termination condition is that the current discharge pressure of the secondary compressor exceeds the upper limit of the discharge pressure or the current evaporation temperature of the load evaporator reaches the upper limit of the evaporation temperature.

[0014] If the first termination condition is met, stop adjusting the opening of the secondary expansion valve.

[0015] In some embodiments, the secondary refrigeration module further includes a first bypass, one end of which is connected to the outlet end of the evaporator-condenser and the other end of which is connected to the return gas end of the secondary compressor. A first regulating expansion valve is provided on the first bypass.

[0016] When the first termination condition and the overload condition are met, the circulation pump is started, including:

[0017] When the first termination condition and the overload condition are met, the current secondary return gas superheat of the secondary compressor is obtained.

[0018] If the current secondary return gas superheat exceeds the upper limit of the second return gas superheat, the circulation pump is turned on, and the upper limit of the second return gas superheat is greater than the upper limit of the first return gas superheat.

[0019] If the current secondary return gas superheat does not exceed the upper limit of the second return gas superheat, the first regulating expansion valve is opened.

[0020] In some embodiments, after starting the circulation pump if the current return gas superheat exceeds the upper limit of the second return gas superheat, the method further includes:

[0021] Obtain the current status data of the temperature control system, and determine whether the temperature control system meets the normal conditions based on the current status data. The normal conditions are that either the secondary return gas superheat or the secondary exhaust temperature is within the allowable range.

[0022] If the aforementioned conventional conditions are not met, the first regulating expansion valve will be opened.

[0023] In some embodiments, opening the first regulating expansion valve includes:

[0024] The current secondary exhaust temperature is acquired multiple times. Each time the current secondary exhaust temperature is acquired, the exhaust temperature range in which the current secondary exhaust temperature is located is determined as the target exhaust temperature range from multiple exhaust temperature ranges with decreasing temperature settings and all temperature values ​​not lower than the upper limit of exhaust temperature. The first regulating expansion valve is controlled to work according to the set opening degree associated with the target exhaust temperature range until the current secondary exhaust temperature does not exceed the upper limit of exhaust temperature.

[0025] The higher the temperature in the exhaust temperature range, the greater the associated set opening degree.

[0026] In some embodiments, activating the circulation pump in the low-load control mode includes:

[0027] S41. In the low-load control mode, first adjust the opening of the secondary expansion valve to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when the second termination condition and the low-load condition are met, start the circulation pump.

[0028] In some embodiments, the primary refrigeration module further includes a second bypass, one end of which is connected to the discharge end of the primary compressor and the other end of which is connected to the return end of the primary compressor, and a second regulating expansion valve is provided on the second bypass.

[0029] In the low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when both the second termination condition and the low-load condition are met, the circulation pump is started, including:

[0030] In the low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when the second termination condition and the low-load condition are met, the second regulating expansion valve is opened.

[0031] After opening the second regulating expansion valve, determine whether the temperature control system meets the normal conditions based on the current status data. If not, start the circulation pump.

[0032] In some embodiments, the temperature control system further includes an electric heater for regulating the load temperature;

[0033] Adjust the opening of the secondary expansion valve to gradually reduce the evaporation temperature of the loaded evaporator until the second termination condition is met, including:

[0034] The opening of the secondary expansion valve is adjusted at set intervals so that the evaporation temperature of the load evaporator drops by the set temperature each time.

[0035] After each adjustment, after the evaporation temperature of the load evaporator stabilizes for a set time, it is determined whether the temperature control system meets the second termination condition. The second termination condition is that the duty cycle decay of the electric heater exceeds the decay threshold or the current evaporation temperature of the load evaporator reaches the lower limit of the evaporation temperature.

[0036] If the second termination condition is met, stop adjusting the opening of the secondary expansion valve.

[0037] In some embodiments, opening the second regulating expansion valve includes:

[0038] Obtain the first-stage discharge superheat and the first-stage return pressure of the first-stage compressor;

[0039] If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first-stage return gas pressure is lower than the first back pressure critical value, the second regulating expansion valve is controlled to operate according to either the first condition or the second condition. The first condition is to control the opening of the second regulating expansion valve to a set opening, and to close the second regulating expansion valve when the first-stage return gas pressure is greater than the second back pressure critical value, wherein the first back pressure critical value is less than the second back pressure critical value. The second condition is to control the opening of the second regulating expansion valve according to the opening matched to the target production temperature of the temperature control system.

[0040] If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first regulating expansion valve is closed, and if the actual production temperature of the temperature control system is lower than its target production temperature, then the opening degree of the second regulating expansion valve is controlled according to the opening degree matched to the target production temperature of the temperature control system.

[0041] In some embodiments, controlling the opening of the second regulating expansion valve according to the opening degree matched to the target production temperature of the temperature control system includes:

[0042] Among the multiple production temperature ranges set by the self-defined temperature increment, the production temperature range in which the target production temperature is located is determined as the target production temperature range;

[0043] The second regulating expansion valve is controlled to operate according to a set opening degree associated with the target production temperature range, wherein the set opening degree associated with the higher the temperature of the production temperature range is is smaller.

[0044] In some embodiments, a cooling valve for regulating flow rate is provided on the cooling circuit;

[0045] Starting the circulation pump also includes:

[0046] The opening degree of the cooling valve is controlled according to the difference between the actual outlet temperature and the set outlet temperature of the cooling circuit. The larger the difference, the larger the opening degree of the cooling valve, and vice versa.

[0047] Secondly, this application proposes a temperature control system, comprising:

[0048] The primary refrigeration module includes a primary compressor, a primary condenser, a primary expansion valve, and an evaporator-condenser arranged sequentially in the primary refrigeration circuit.

[0049] The cooling circuit is thermally coupled to the primary refrigeration circuit via the primary condenser.

[0050] The secondary refrigeration module includes a secondary compressor, a secondary expansion valve, and a load evaporator arranged sequentially in the secondary refrigeration circuit. The primary refrigeration module and the secondary refrigeration module are thermally coupled through the evaporator-condenser.

[0051] A heat exchange module includes a first heat exchanger, a heat exchange section, a heat exchange circuit, and a circulating pump. The circulating pump is located in the heat exchange circuit. The first heat exchanger is thermally coupled to the heat exchange circuit and the secondary refrigeration circuit, and is arranged on the secondary refrigeration circuit between the load evaporator and the secondary compressor. The heat exchange circuit is filled with a heat exchange medium. The heat exchange section is thermally coupled to the heat exchange circuit and the cooling circuit.

[0052] In some embodiments, the secondary refrigeration module further includes a first bypass, one end of which is connected to the outlet end of the evaporator-condenser, and the other end of which is connected to the return gas end of the secondary compressor. A first regulating expansion valve is provided on the first bypass; and / or,

[0053] The primary refrigeration module further includes a second bypass, one end of which is connected to the discharge end of the primary compressor, and the other end of which is connected to the return end of the primary compressor. A second regulating expansion valve is provided on the second bypass; and / or,

[0054] The temperature control module includes an electric heater disposed on the load evaporator; and / or

[0055] The primary condenser serves as the heat exchange unit, and simultaneously thermally couples the cooling circuit with the heat exchange circuit and the primary refrigeration circuit.

[0056] Thirdly, this application proposes a testing device, including a temperature control system and a testing terminal, wherein the temperature control system is used to adjust the temperature of the testing terminal;

[0057] The temperature control system performs the control method described in the first aspect, or the temperature control system is the temperature control system proposed in the second aspect.

[0058] Compared with the prior art, this application has the following beneficial effects:

[0059] The control method, system, and testing equipment of the aforementioned temperature control system enable the circulation pump to be activated when the temperature control system is overloaded or underloaded. This allows the cooling medium in the cooling circuit to exchange heat with the return gas refrigerant of the secondary compressor through the heat exchange medium in the heat exchange module, thus preventing liquid carryover or overheating of the return gas from the secondary compressor and improving the service life of the secondary compressor. Attached Figure Description

[0060] Various other advantages and benefits will become apparent to those skilled in the art upon reading the detailed description of the preferred embodiments below. The accompanying drawings are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, the same reference numerals denote the same parts throughout the drawings. In the drawings:

[0061] Figure 1 This is a schematic diagram of a temperature control system according to some embodiments.

[0062] Figure 2 This is a flowchart illustrating the control method of a temperature control system according to some embodiments.

[0063] Figure 3 This is a detailed flowchart of S30 in some embodiments.

[0064] Figure 4 This is a detailed flowchart of S31 in some embodiments.

[0065] Figure 5 This is a detailed flowchart of S40 in some embodiments.

[0066] Figure 6 This is a detailed flowchart of S41 in some embodiments.

[0067] Figure 7 This is a detailed flowchart of S411 in some embodiments.

[0068] The reference numerals in the detailed embodiments are as follows:

[0069] 10. Primary refrigeration module; 11. Primary compressor; 12. Primary condenser; 13. Primary expansion valve; 14. Evaporator-condenser; 15. Cooling valve; 16. Second bypass; 17. Second regulating expansion valve; L1. Primary refrigeration circuit; L2. Cooling circuit;

[0070] 20. Secondary refrigeration module; 21. Secondary compressor; 22. Secondary expansion valve; 23. Load evaporator; 24. First bypass; 25. First regulating expansion valve; L3. Secondary refrigeration circuit;

[0071] 30. Heat exchange module; 31. First heat exchanger; 32. Heat exchange section; 33. Heat exchange circuit; 34. Circulation pump. Detailed Implementation

[0072] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application are described in detail below with reference to the accompanying drawings. Many specific details are set forth in the following description to provide a thorough understanding of this application. However, this application can be implemented in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of this application. Therefore, this application is not limited to the specific embodiments disclosed below.

[0073] In the description of this application, it should be understood that, where they appear, the terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application.

[0074] Furthermore, where applicable, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0075] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., shall be interpreted broadly. For example, they may refer to a fixed connection, a detachable connection, or an integral part; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; they may refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0076] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "on top of," and "over" the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0077] It should be noted that, if an element is described as "fixed to" or "set on" another element, it can be directly on the other element or there may be an intervening element. When an element is described as "connected to" another element, it can be directly connected to the other element or there may be an intervening element. The terms "vertical," "horizontal," "upper," "lower," "left," "right," and similar expressions used herein are for illustrative purposes only and do not represent the only possible implementation.

[0078] To address the problem of a mismatch between the cooling capacity and load demand of a refrigeration system, leading to overload or underload and a reduced lifespan of the compressor, this application first proposes a temperature control system and a control method for the temperature control system.

[0079] Please refer to Figure 1 The temperature control system in this embodiment includes a primary refrigeration module 10, a secondary refrigeration module 20, a heat exchange module 30, and a cooling circuit L2.

[0080] The primary refrigeration module 10 includes a primary compressor 11, a primary condenser 12, a primary expansion valve 13, and an evaporator-condenser 14 arranged sequentially in the primary refrigeration circuit L1. The cooling circuit L2 is thermally coupled to the primary refrigeration circuit L1 via the primary condenser L1.

[0081] The secondary refrigeration module 20 includes a secondary compressor 21, a secondary expansion valve 22, and a load evaporator 23 arranged sequentially in the secondary refrigeration circuit L3. The primary refrigeration module 10 and the secondary refrigeration module 20 are thermally coupled via an evaporator-condenser 14. Understandably, in the secondary refrigeration circuit L3, the evaporator-condenser 14 is arranged between the secondary compressor 21 and the secondary expansion valve 22.

[0082] The heat exchange module 30 includes a first heat exchanger 31, a heat exchange section 32, a heat exchange circuit 33, and a circulating pump 34. The circulating pump 34 is located in the heat exchange circuit 33. The first heat exchanger 31 is thermally coupled to the heat exchange circuit 33 and the secondary refrigeration circuit L3, and is arranged on the secondary refrigeration circuit L3 between the load evaporator 23 and the secondary compressor 21. The heat exchange circuit 33 is filled with heat exchange medium. The heat exchange section 32 is thermally coupled to the heat exchange circuit 33 and the cooling circuit L2.

[0083] In practical applications, the temperature control system has a cooling mode. In cooling mode, the primary compressor 11 operates and delivers high-temperature gaseous primary refrigerant to the primary condenser 12. Simultaneously, cooling water flows through the cooling circuit L2, passing through the primary condenser 12 and exchanging heat with the high-temperature gaseous primary refrigerant entering the condenser 12. The high-temperature gaseous primary refrigerant releases heat and becomes medium-temperature liquid primary refrigerant, while the cooling water absorbs heat and rises in temperature. The medium-temperature liquid primary refrigerant is then throttled and cooled by the primary expansion valve 13, becoming low-temperature liquid primary refrigerant.

[0084] Meanwhile, the secondary compressor 21 operates, supplying high-temperature gaseous secondary refrigerant to the evaporator-condenser 14. The low-temperature liquid primary refrigerant and the high-temperature gaseous secondary refrigerant exchange heat at the evaporator-condenser 14. The primary refrigerant absorbs heat, becomes a high-temperature gas, and flows back to the return gas end of the primary compressor 11, thus completing the cycle. The secondary refrigerant releases heat, becomes a medium-temperature liquid, and flows to the secondary expansion valve 22. After being throttled and cooled by the secondary expansion valve 22, it becomes a low-temperature liquid, then absorbs load heat at the load evaporator 23 to achieve load cooling, and finally flows back to the return gas end of the secondary compressor 21, thus completing the cycle.

[0085] The heat exchange circuit 33 is filled with a heat exchange medium. The heat exchange medium can be, but is not limited to, fluorinated liquid, silicone oil, liquid carbon dioxide, water, etc. The cooling circuit L2 is circulated with a cooling medium. For ease of explanation, this article uses cooling water as an example, but this is not a limitation on the type of cooling medium. A circulation pump 34 is installed on the heat exchange circuit 33, and the heat exchange medium circulates within the heat exchange circuit 33 under the action of the circulation pump 34.

[0086] The first heat exchanger 31 thermally couples the heat exchange circuit 33 and the secondary refrigeration circuit L3, and the heat exchange section 32 thermally couples the heat exchange circuit 33 and the cooling circuit L2. Alternatively, the first heat exchanger 31 may have two flow channels, one arranged in the heat exchange circuit 33 and the other in the secondary refrigeration circuit L3. Alternatively, the heat exchange section 32 may have two flow channels, one arranged in the heat exchange circuit 33 and the other in the cooling circuit L2.

[0087] In the secondary refrigeration circuit L3, a first heat exchanger 31 is arranged between the load evaporator 23 and the secondary compressor 21. That is, the heat exchange medium in the heat exchange circuit 33 exchanges heat with the refrigerant returning to the secondary compressor 21 via the first heat exchanger 31. The refrigerant returning to the secondary compressor 21 is called the return gas refrigerant. The return gas refrigerant and the heat exchange medium exchange heat at the first heat exchanger 31, and the heat exchange medium and the cooling water exchange heat at the heat exchange section 32.

[0088] When the required cooling capacity of the load exceeds the cooling capacity of the evaporator 23, the temperature control system is overloaded, causing the return gas refrigerant to overheat. When the temperature of the return gas refrigerant is higher than that of the heat exchange medium, the heat exchange medium absorbs the temperature of the return gas refrigerant at the first heat exchanger 31, causing the temperature of the return gas refrigerant to drop and solving the problem of excessively high return gas temperature. At the same time, after the heat exchange medium absorbs heat and rises in temperature at the first heat exchanger 31, it is cooled down by cooling water at the heat exchange section 32, and this cycle continues.

[0089] When the required cooling capacity of the load is lower than that of the load evaporator 23, the temperature control system is in a low-load state, and the liquid secondary refrigerant does not evaporate sufficiently, resulting in liquid carryover in the return gas of the secondary compressor 21. At this time, the temperature of the return gas refrigerant is low. When the temperature of the return gas refrigerant is lower than that of the heat exchange medium, the heat exchange medium heats the return gas refrigerant at the first heat exchanger 31, causing the liquid components in the return gas refrigerant to absorb heat and turn into gas, thus solving the problem of liquid carryover in the return gas. At the same time, after the heat exchange medium releases heat and cools down at the first heat exchanger 31, it is heated up by cooling water at the heat exchange section 32, and the cycle continues.

[0090] In this way, the temperature control system achieves indirect heat exchange between cooling water and return gas refrigerant through the heat exchange medium, solving the problem of overheating or liquid carryover of return gas refrigerant and improving the service life of the secondary compressor 21.

[0091] It is worth noting that the cooling valve 15 is used to control the flow rate of the cooling circuit L2 in order to adjust the heat exchange capacity of the cooling circuit L2.

[0092] Based on the temperature control system provided in the above embodiments, this application proposes a control method for the temperature control system, applied to the above-mentioned temperature control system, with reference to... Figure 2 The control method includes:

[0093] S10. In cooling mode, acquire the status data of the temperature control system, including the secondary return superheat and secondary exhaust temperature of the secondary compressor 21.

[0094] For ease of description, this application refers to the return gas superheat of the secondary compressor 21 as the secondary return gas superheat, and the discharge temperature of the secondary compressor 21 as the secondary discharge temperature.

[0095] Understandably, the secondary return gas superheat is determined by the difference between the return gas temperature of the secondary compressor 21 and the saturated evaporation temperature corresponding to the return gas pressure of the secondary compressor 21.

[0096] The return gas pressure of the secondary compressor 21 refers to the pressure of the return refrigerant. The return gas pressure of the secondary compressor 21 can be measured by a pressure sensor. In one embodiment, the pressure sensor is installed at the low-pressure detection port of the secondary compressor 21. In another embodiment, the pressure sensor is installed at the inlet end of the first heat exchanger 31 located in the secondary refrigeration circuit L3. The saturated evaporation temperature corresponding to the return gas pressure of the secondary compressor 21 can be obtained by looking up the type of secondary refrigerant; there is a one-to-one correspondence between the two.

[0097] The return gas temperature of the secondary compressor 21 refers to the actual temperature of its return refrigerant. In one embodiment, a contact temperature sensor is installed at the return gas inlet of the secondary compressor 21 to more accurately measure its return gas temperature. In another embodiment, a temperature sensor is installed at the inlet of the first heat exchanger 31 located in the secondary refrigeration circuit L3 to detect its return gas temperature.

[0098] Secondary exhaust temperature refers to the temperature of the refrigerant discharged by the secondary compressor 21. A higher secondary return gas superheat means a higher vapor temperature entering the secondary compressor 21. Combined with the heat generated by compression work, this results in a higher secondary exhaust temperature. In one embodiment, the secondary exhaust temperature is detected by a temperature sensor installed on the exhaust pipe of the secondary compressor 21.

[0099] S20. Based on the status data, determine whether the temperature control system meets the overload or low load conditions. The overload condition is that the secondary return gas superheat exceeds the upper limit of the first return gas superheat and the secondary exhaust temperature exceeds the upper limit of the exhaust temperature. The low load condition is that the secondary return gas superheat is lower than the lower limit of the return gas superheat and the secondary exhaust temperature is lower than the lower limit of the exhaust temperature.

[0100] The upper limit values ​​for the first return gas superheat and the upper limit value for the exhaust temperature are used to protect the second-stage compressor 21 from return gas overheating. The upper limit values ​​for the first return gas superheat and the upper limit value for the exhaust temperature are usually related to the type of the second-stage compressor 21 and can be set in advance based on experience or the usage requirements of the second-stage compressor 21.

[0101] When the temperature control system is in cooling mode, it can switch between three control modes: normal control mode, overload control mode, and low load control mode. In normal control mode, at the same production temperature, the cooling capacity required by the load is basically the same as that required by the testing equipment, meaning the load performance is basically the same as the testing equipment performance, and the operating state of the temperature control system is basically the same as the testing state, indicating normal operation of the temperature control system. At this time, either the secondary return gas superheat or the secondary exhaust temperature is within the allowable range (i.e., at least one is within the allowable range). It is worth noting that the allowable range for the secondary return gas superheat is [lower limit of return gas superheat, upper limit of first return gas superheat], and the allowable range for the secondary exhaust temperature is [lower limit of exhaust temperature, upper limit of exhaust temperature]. In a specific example, the allowable range for the secondary return gas superheat is 3℃~30℃, and the allowable range for the secondary exhaust temperature is 70℃~100℃.

[0102] When both the secondary return gas superheat and the secondary exhaust temperature exceed their respective upper limits, the temperature control system is deemed to be overloaded, indicating that the system is in an overload state. The heat load on the load evaporator 23 exceeds the cooling capacity provided by the temperature control system. Under the same production temperature, the heat load generated by the load exceeds the heat load required by the test equipment. When the temperature control system is overloaded, the cooling capacity required by the load exceeds the cooling capacity that the load evaporator 23 can provide. Insufficient liquid refrigerant and excessive heat absorption by the gaseous refrigerant lead to excessively high secondary return gas superheat, which in turn causes excessively high secondary exhaust temperature, shortening the service life of the secondary compressor 21.

[0103] When the secondary return gas superheat is lower than the lower limit of the return gas superheat and the lower limit of the secondary exhaust gas temperature, the temperature control system meets the low load condition, indicating that the temperature control system is in a low load state. The heat load of the load evaporator 23 is lower than the cooling capacity provided by the temperature control system. At the same production temperature, the heat load generated by the load is lower than the heat load required by the test equipment. When the heat load of the load evaporator 23 is too small, that is, in a low load state, the secondary refrigerant does not absorb heat sufficiently at the load evaporator 23, and a large amount of liquid refrigerant flows to the return gas end of the secondary compressor 21, resulting in "liquid slugging". Due to the large amount of liquid refrigerant in the secondary compressor 21, the lubricating oil is diluted, leading to lubrication failure.

[0104] S30. When the overload condition is met, the temperature control system enters the overload control mode. In the overload control mode, the circulating pump 34 is turned on so that the cooling circuit L2 indirectly cools the return gas refrigerant of the secondary compressor 21 through the heat exchange circuit 33.

[0105] When the temperature control system enters overload control mode and the circulating pump 34 is activated, the heat exchange medium circulates within the heat exchange circuit 33 under the drive of the circulating pump 34. It absorbs heat from the return gas refrigerant of the secondary compressor 21 at the first heat exchanger 31, causing the return gas refrigerant temperature to drop. Then, the heat-absorbing medium transfers the absorbed heat to the cooling water in the cooling circuit L2 at the heat exchange section 32, continuously circulating. In this way, the heat from the return gas refrigerant is transferred to the cooling water through the heat exchange medium, achieving the purpose of reducing the exhaust temperature and return gas superheat of the secondary compressor 21.

[0106] S40. When the low load condition is met, the temperature control system enters the low load control mode. In the low load control mode, the circulation pump 34 is turned on so that the cooling circuit L2 indirectly heats the return gas refrigerant of the secondary compressor 21 through the heat exchange circuit 33.

[0107] When the temperature control system enters the low-load control mode and the circulating pump 34 is turned on, the heat exchange medium circulates within the heat exchange loop 33 under the drive of the circulating pump 34. The heat exchange medium heats the return gas refrigerant at the first heat exchanger 31, causing the liquid components in the return gas refrigerant to absorb heat and turn into gas, thus solving the problem of liquid carryover in the return gas. Then, the cooled heat exchange medium is heated by the cooling water in the heat exchange section 32, and so on. This cycle indirectly transfers the temperature of the cooling water to the return gas refrigerant through the heat exchange medium, solving the problem of liquid carryover in the return gas refrigerant.

[0108] In summary, the control method of this application embodiment determines whether the temperature control system is overloaded or underloaded by monitoring the data of secondary superheat and secondary exhaust temperature. When overload or underload exists, the circulation pump 34 is turned on, and the temperature of the return gas refrigerant of the secondary compressor 21 is indirectly regulated by the cooling water on the cooling circuit L2 through the heat exchange circuit, so as to avoid overheating or liquid carryover of the return gas refrigerant and greatly improve the service life of the compressor.

[0109] Moreover, by using the cooling water on the cooling circuit L2 to improve the temperature and state of the return refrigerant, the heat exchange capacity of the cooling water in the cooling circuit L2 is fully utilized, and the heat exchange efficiency of the cooling water is improved. This not only has a significant regulating effect, but is also economical.

[0110] In addition, by using heat exchange circuit 33 as an intermediate circuit to realize heat exchange between cooling circuit L2 and primary refrigeration circuit L1, the unstable primary refrigeration circuit L1, which is at risk of phase change, is isolated from the stable cooling circuit L2. Personnel or equipment of the cooling water system will not come into direct contact with the refrigerant, thus improving system safety.

[0111] In some embodiments, please refer to Figure 3 In S30, under overload control mode, the circulating pump is activated, including:

[0112] S31. In overload control mode, first adjust the opening of the secondary expansion valve 22 to gradually increase the evaporation temperature of the load evaporator 23 until the first termination condition is met; when the first termination condition and the overload condition are met, start the circulation pump 34.

[0113] Specifically, the evaporation temperature of the load evaporator 23 is increased by increasing the opening degree of the secondary expansion valve 22. In other words, the opening degree of the secondary expansion valve 22 is adjusted using the evaporation temperature as a reference. At this point, adjusting the opening degree of the secondary expansion valve with the evaporation temperature as the control target only requires monitoring the evaporation temperature of the load evaporator 23. The reference is more direct, simplifying the control logic and helping to improve the utilization of the heat exchange area of ​​the load evaporator 23. The evaporation temperature of the load evaporator 23 can be determined by monitoring the pressure of the load evaporator 23 and understanding the relationship between pressure and saturation temperature.

[0114] When the temperature control system meets the conditions for entering overload control mode, in order to mitigate the dangers of overload, the opening of the secondary expansion valve 22 is gradually increased, thereby gradually increasing the refrigerant flow into the load evaporator 23. As more liquid refrigerant flows into the load evaporator 23, sufficient liquid evaporates over a longer pipe length, effectively reducing return gas superheat and thus lowering the exhaust temperature. Furthermore, the opening is adjusted gradually to avoid an excessive increase in opening at once, which could lead to the risk of "liquid slugging" due to excessive liquid refrigerant.

[0115] When the return gas superheat is extremely high, the latter half of the pipe in the secondary refrigeration circuit L3, where the load evaporator 23 is located, is in a "dry-burning" state and is not effectively utilized. Increasing the opening of the secondary expansion valve 22 increases the supply of liquid refrigerant, ensuring that liquid refrigerant is also present in the latter half of the pipe. This increases the effective heat exchange area of ​​the load evaporator 23, allowing it to provide the maximum possible cooling capacity to combat the high heat load under the current limit, effectively and quickly mitigating the adverse effects caused by "overload".

[0116] It is worth noting that, due to the increased liquid refrigerant content within the load evaporator 23, the gaseous refrigerant produced by evaporation is also more concentrated, leading to an increase in pressure within the load evaporator 23. According to the refrigerant's saturated pressure-temperature characteristic, an increase in pressure results in a corresponding increase in the saturated evaporation temperature, i.e., an increase in evaporation temperature. While this increase in evaporation temperature reduces the heat transfer temperature difference with the load and slightly decreases the heat exchange per unit area, the overall heat exchange capacity of the load evaporator 23 increases due to the increased liquid refrigerant content and effective heat exchange area.

[0117] In other words, when the temperature control system enters the overload control mode, the evaporation temperature of the load evaporator 23 is increased by gradually increasing the opening of the secondary expansion valve 22, thereby improving the heat exchange efficiency of the load evaporator 23. By optimizing the operating parameters, the "overload" problem is improved, the cost is reduced, and the cooling capacity of the secondary refrigeration module 20 can be better matched with the actual load demand.

[0118] The opening of the secondary expansion valve 22 cannot be increased indefinitely. If the opening is too large, the liquid refrigerant cannot exchange heat in time, leading to liquid carryover in the return gas and causing liquid slugging in the secondary compressor 21. When the opening of the secondary expansion valve 22 is increased to a certain extent and the temperature control system meets the first termination condition, it indicates that further increasing the opening of the secondary expansion valve 22 will have significant negative effects, such as liquid carryover in the return gas. At this point, the adjustment of the opening of the secondary expansion valve 22 should be stopped.

[0119] If the temperature control system still meets the overload condition after the opening of the secondary expansion valve 22 is terminated, it indicates that the secondary compressor 21 still has problems with return gas overheating and exhaust gas overheating. In this case, the circulation pump 34 is turned on and the heat exchange module 30 is started to remove the temperature of the return gas refrigerant. External force is used to solve the return gas overheating problem, thereby solving the exhaust gas overheating problem. This makes the cooling capacity of the secondary refrigeration module 20 match the load requirements and improves the service life of the secondary compressor 21.

[0120] The secondary expansion valve 22 is a passive, energy-efficient adjustment method. It is used preferentially to regulate the return refrigerant temperature of the secondary compressor 21, reducing energy consumption and making the cooling capacity of the secondary refrigeration module 20 more compatible with the load demand. In contrast, starting the circulation pump 34 requires a large amount of water and electricity, making it a high-energy-consuming adjustment method. The circulation pump 34 is only activated when the secondary expansion valve 22 cannot adjust, thus helping to reduce energy consumption.

[0121] In some embodiments, refer to Figure 4 In step S31, the opening of the secondary expansion valve 22 is adjusted to gradually increase the evaporation temperature of the load evaporator 23 until the first termination condition is met, specifically including:

[0122] S311. Adjust the opening of the secondary expansion valve 22 at set intervals so that the evaporation temperature of the load evaporator 23 rises to the set temperature each time.

[0123] For example, adjust the opening of the secondary expansion valve 22 every 1 to 5 minutes to increase the evaporation temperature by 1°C each time.

[0124] S312. After each adjustment, when the evaporation temperature of the load evaporator 23 has stabilized for a set time, determine whether the temperature control system meets the first termination condition. The first termination condition is that the current discharge pressure of the secondary compressor 21 exceeds the upper limit of the discharge pressure or the current evaporation temperature of the load evaporator 23 reaches the upper limit of the evaporation temperature.

[0125] After each adjustment, wait 10-30 seconds to determine whether the discharge pressure of the secondary compressor 21 exceeds the upper limit of the discharge pressure, or whether the evaporation temperature of the load evaporator 23 reaches the upper limit of the evaporation temperature. If either condition is met, it indicates that the temperature control system meets the first termination condition, and the adjustment of the opening of the secondary expansion valve 22 is stopped.

[0126] The discharge pressure of the secondary compressor 21 refers to the pressure on the discharge side of the secondary compressor 21. A pressure sensor is typically installed on the pipeline connecting the discharge port of the secondary compressor 21 and the inlet of the evaporator-condenser 14 to detect the discharge pressure of the secondary compressor 21.

[0127] When the discharge pressure exceeds the upper limit, it means that the condensing capacity of the evaporator-condenser 14 is insufficient. If the secondary expansion valve 22 is further enlarged, the secondary compressor 21 will draw in more gaseous refrigerant. This refrigerant will be pumped by the secondary compressor 21 into the overloaded evaporator-condenser 14, further deteriorating the condensing effect. This will cause the motor of the secondary compressor 21 to overload and burn out due to the extremely increased load. The lubricating oil will rapidly carbonize at extreme temperatures, losing its lubricating ability, causing mechanical wear of the secondary compressor 21, and ultimately rendering it unusable. The upper limit of the discharge pressure is a set value that can be set according to the configuration of each component of the temperature control system.

[0128] When the evaporation temperature reaches its upper limit, it means that the heat transfer temperature difference between the refrigerant and the load becomes very small. If the opening of the secondary expansion valve 22 is further increased, the load evaporator 23 will be filled with liquid refrigerant, and the heat exchange area of ​​the load evaporator 23 cannot be increased further. However, the heat transfer temperature difference will continue to decrease, resulting in a decrease in the overall cooling capacity of the load evaporator 23, a sharp increase in the power consumption of the secondary compressor 21, and a significant increase in the risk of liquid slugging.

[0129] S313. If the first termination condition is met, stop adjusting the opening of the secondary expansion valve 22.

[0130] Therefore, when adjusting the opening of the secondary expansion valve 22 to increase the evaporation temperature, when the first termination condition is reached, in order to protect the compressor and maintain stable system operation, it is necessary to stop adjusting the opening of the secondary expansion valve 22.

[0131] In some embodiments, refer to Figure 1The secondary refrigeration module 20 also includes a first bypass 24, one end of which is connected to the outlet end of the evaporator condenser 14, and the other end is connected to the return gas end of the secondary compressor 21. A first regulating expansion valve 25 is provided on the first bypass 24.

[0132] Continue to refer to Figure 4 In S31, when both the first termination condition and the overload condition are met, the circulating pump 34 is started, specifically including:

[0133] S314. When the first termination condition and the overload condition are met, obtain the current secondary return gas superheat of the secondary compressor 21.

[0134] S315. If the current secondary return gas superheat exceeds the upper limit of the second return gas superheat, start the circulation pump 34. The upper limit of the second return gas superheat is greater than the upper limit of the first return gas superheat.

[0135] S316. If the current secondary return gas superheat does not exceed the upper limit of the secondary return gas superheat, open the first regulating expansion valve 25.

[0136] When the temperature control system meets the first termination condition but not the overload condition, it indicates that the temperature control system has entered normal operation through the adjustment of the secondary expansion valve 22, and the temperature control system has entered the normal control mode. In the normal control mode, the circulation pump 34 is turned off.

[0137] When the temperature control system meets both the first termination condition and the overload condition, it indicates that adjusting the opening of the secondary expansion valve 22 has not completely alleviated the problems of overheating of the return gas and exhaust gas of the secondary compressor 21, and further adjustment is required. At this stage, this application proposes two solutions.

[0138] Specifically, the current secondary return gas superheat of the secondary compressor 21 is first obtained. Based on the relationship between the current secondary return gas superheat and the upper limit of the second return gas superheat, the next action is determined. The upper limit of the second return gas superheat is higher than the upper limit of the first return gas superheat; for example, if the upper limit of the first return gas superheat is 25°C, the upper limit of the second return gas superheat could be 30°C. The first regulating expansion valve 25 can be a liquid-injection electronic expansion valve.

[0139] The first solution is: if the current secondary return gas superheat exceeds the upper limit of the secondary return gas superheat, the temperature control system is overloaded. In this case, the circulating pump 34 is turned on, and the heat of the return gas refrigerant is transferred to the cooling water through the circulating heat exchange medium, so as to achieve rapid and effective cooling of the return gas refrigerant and prevent the temperature control system from entering a deteriorating state.

[0140] The second solution is as follows: If the current secondary return gas superheat does not exceed the upper limit of the secondary return gas superheat, it indicates that the overload of the temperature control system can still be withstood. At this time, the first regulating expansion valve 25 is opened, and the first bypass 24 is opened. In the secondary refrigeration circuit L3, the medium-temperature liquid secondary refrigerant flowing from the evaporator condenser 14 is divided into two paths. One path flows to the secondary expansion valve 22 and absorbs heat at the load evaporator 23, becoming a high-temperature gaseous refrigerant that flows back to the secondary compressor 21. The other path flows to the first bypass 24 and is cooled by the first regulating expansion valve 25, becoming a low-temperature gas-liquid mixture of secondary refrigerant that flows to the secondary compressor 21. During this process, the two secondary refrigerants mix, and the low-temperature liquid refrigerant absorbs heat from the high-temperature gaseous refrigerant to evaporate and form gaseous refrigerant. This significantly reduces the temperature of the refrigerant entering the secondary compressor 21, improving its cooling capacity, reducing the temperature of the return gas refrigerant, and thus reducing the secondary return gas superheat and exhaust temperature of the secondary compressor 21, protecting the secondary compressor 21 and extending its service life.

[0141] In this embodiment, when the secondary return gas superheat does not exceed the upper limit of the second return gas superheat, the overload load is still bearable, and the return gas superheat of the secondary compressor 21 is still within the acceptable range. The second solution is then activated: the low-temperature secondary refrigerant prepared using the first bypass 24 and the first regulating expansion valve 25 is used to lower the return gas temperature of the secondary compressor 21, preventing the discharge temperature of the secondary compressor 21 from becoming too high. This allows the cooling capacity of the secondary refrigeration module 20 to better match the load demand. At this point, the system achieves stable operation and a higher safety margin at a slight efficiency cost, with low energy consumption.

[0142] When the superheat of the secondary return gas exceeds the upper limit of the second return gas superheat, the superheat of the return gas of the secondary compressor 21 is high, and the system overload is too large. The first solution is activated, which is to use the heat exchange medium as a medium to realize indirect heat exchange between the cooling water and the secondary refrigerant. This can solve the problem of return gas superheat more effectively, quickly and reliably, and avoid system failure.

[0143] By combining these two complementary solutions, minor problems are addressed with minor solutions and major problems with major solutions, a balance is achieved between the efficiency, safety, and energy consumption of the temperature control system, greatly improving system reliability and reducing potential costs.

[0144] In a further embodiment, refer to Figure 3 If the current secondary return gas superheat exceeds the upper limit of the secondary return gas superheat, after starting S315 of the circulation pump 34, the following also applies:

[0145] S317. Obtain the current status data of the temperature control system, and determine whether the temperature control system meets the normal conditions based on the current status data. The normal conditions are that either the secondary return gas superheat or the secondary exhaust temperature is within the allowable range.

[0146] S318. If the normal conditions are not met, open the first regulating expansion valve 25.

[0147] After the circulating pump 34 is started, the cooling water, through the heat exchange medium, powerfully cools the return refrigerant of the secondary compressor 21. During this process, the current status data of the temperature control system can be acquired at set intervals. Based on the current status data, it is determined whether the normal conditions are met, that is, whether the return gas superheat or the exhaust temperature is within the allowable range. As long as either of these two conditions is met, the normal conditions are satisfied.

[0148] When the normal conditions are met, it means that when the circulating pump 34 is turned on and the temperature control system is applied to the existing load, the problem of overheating of the return gas or exhaust gas of the secondary compressor 21 has been resolved, and the temperature control system is within a safe operating range. Thus, the current operation is maintained and the circulating pump 34 is kept on.

[0149] If the normal conditions are not met, it means that turning on the circulation pump 34 still cannot completely solve the problem of overheating of the return gas of the secondary compressor 21. At the same time, turn on the circulation pump 34 and the first regulating expansion valve 25. The first solution and the second solution are used at the same time to completely solve the problems of overheating of the return gas and overheating of the exhaust gas of the secondary compressor 21.

[0150] In some embodiments, in S318, opening the first regulating expansion valve 25 includes:

[0151] The system repeatedly acquires the current secondary exhaust temperature. Each time the current secondary exhaust temperature is acquired, it selects the target exhaust temperature range from multiple exhaust temperature ranges with decreasing temperatures, all of which are not lower than the upper limit of the exhaust temperature. The first regulating expansion valve 25 is then controlled according to a set opening degree associated with the target exhaust temperature range until the current secondary exhaust temperature does not exceed the upper limit of the exhaust temperature. The higher the temperature within the exhaust temperature range, the larger the associated set opening degree.

[0152] Specifically, multiple exhaust temperature ranges are pre-set, with the temperature value of each range not lower than the upper exhaust temperature limit. The upper exhaust temperature limit can be within the range of [80℃, 100℃], depending on the type of the secondary compressor 21, and is not limited here. For example, the upper exhaust temperature limit is 100℃. Table 1 records the five pre-set exhaust temperature ranges and their corresponding opening degrees in the example. T0 is the upper exhaust temperature limit. Based on T0, an exhaust temperature range is set every set temperature (e.g., 2℃-5℃). In every two adjacent exhaust temperature ranges, the opening degree corresponding to the higher temperature is greater than the opening degree of the lower temperature range by a set percentage. This set percentage can be within the range of 1%-12%.

[0153] Table 1

[0154] Exhaust temperature ℃ Opening ≤T0 0 (T0, T1) Opening degree 1 [T1, T2) Opening degree 2 [T3, T4) Opening 3 [T4, T5) Opening 4

[0155] Each time the current secondary exhaust temperature is obtained, it is first determined whether it exceeds the upper limit of the exhaust temperature. If it does not exceed the limit, the first regulating expansion valve 25 is closed, and its opening is 0. If it exceeds the limit, the exhaust temperature range is further determined. If the current secondary exhaust temperature is in the range (T0, T1), the opening of the first regulating expansion valve 25 is controlled at opening 1. If the current secondary exhaust temperature is in the range [T1, T2), the opening of the first regulating expansion valve 25 is controlled at opening 2. If the current secondary exhaust temperature is in the range [T3, T4), the opening of the first regulating expansion valve 25 is controlled at opening 3. If the current secondary exhaust temperature is in the range [T4, T5), the opening of the first regulating expansion valve 25 is controlled at opening 4.

[0156] The secondary exhaust temperature is the final result of all thermal processes inside the secondary compressor 21. It integrates various factors such as return gas temperature, compression ratio, motor heating, and frictional heat generation, and is the most direct manifestation of the thermal stress borne by the secondary compressor 21. Therefore, adjusting the opening of the first regulating expansion valve 25 based on the secondary exhaust temperature is an efficient and reliable control strategy.

[0157] At the same time, the opening degree is matched according to the exhaust temperature range of the secondary exhaust temperature. The higher the secondary exhaust temperature, the larger the opening degree. This not only avoids the waste of cooling capacity, but also effectively suppresses high temperature, prevents liquid slugging, and reduces the negative impact on the system's heat exchange efficiency.

[0158] In some embodiments, refer to Figure 5 In S40, under low-load control mode, the circulating pump 34 is activated, including:

[0159] S41. In low-load control mode, first adjust the opening of the secondary expansion valve to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when the second termination condition and the low-load condition are met, start the circulation pump 34.

[0160] In low-load control mode, the opening of the secondary expansion valve 22 is reduced first, and the flow rate of liquid refrigerant entering the load evaporator 23 is gradually reduced, so that the cooling capacity of the load evaporator 23 matches its lower heat load, ensuring that the secondary refrigerant can be completely evaporated when it leaves the load evaporator 23, thereby delivering dry superheated steam to the secondary compressor 21, eliminating the risk of liquid slugging and the resulting low-temperature exhaust problem.

[0161] It is worth noting that the opening of the secondary expansion valve 22 is still adjusted here with the evaporation temperature as a reference. Similarly, the opening of the secondary expansion valve is adjusted with the evaporation temperature as the control target. Only the evaporation temperature of the load evaporator 23 needs to be monitored, making the reference more direct and simplifying the control logic. The evaporation temperature of the load evaporator 23 can be determined by monitoring the pressure of the load evaporator 23 and using the correlation between pressure and saturation temperature.

[0162] The opening of the secondary expansion valve 22 cannot be reduced indefinitely. If the opening is too small, the refrigerant flow will be too low, reducing the heat exchange capacity of the load evaporator 23. When the heat exchange capacity of the load evaporator 23 cannot match the heat load generated by the load, the load evaporator 23 will instead enter an overload state. Therefore, when the opening of the secondary expansion valve 22 is reduced to a certain extent, and the temperature control system meets the second termination condition, it indicates that if the temperature control system continues to reduce the opening of the secondary expansion valve 22, it will have significant negative effects, such as overload and compressor overheating. At this point, the adjustment of the opening of the secondary expansion valve 22 is terminated.

[0163] If the temperature control system still meets the low load condition after the opening of the secondary expansion valve 22 is stopped, it indicates that the secondary compressor 21 still has the problem of liquid carrying back gas. In this case, the circulation pump 34 is turned on for adjustment.

[0164] At this point, when the temperature control system enters the low-load control mode, before the circulating pump 34 starts, the evaporation temperature of the load evaporator 23 is first reduced by gradually decreasing the opening of the secondary expansion valve 22 to pre-regulate the temperature of the return gas refrigerant, thereby improving the heat exchange efficiency of the load evaporator 23. This optimization of operating parameters improves the "low-load" problem and reduces costs. If the return gas overheating temperature can be completely resolved through the regulation of the secondary expansion valve 22 without starting the circulating pump 34, the temperature control system will have lower energy consumption, smaller system fluctuations, and higher temperature control accuracy. Furthermore, after the circulating pump 34 starts, the refrigerant flow, pressure, and temperature will be more stable throughout the entire process, resulting in a faster system response and smaller temperature fluctuations.

[0165] In some embodiments, the primary refrigeration module 10 further includes a second bypass 16, one end of which is connected to the exhaust end of the primary compressor 11 and the other end of which is connected to the return end of the primary compressor 11. A second regulating expansion valve 17 is provided on the second bypass 16.

[0166] Reference Figure 6 In S41, under low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when both the second termination condition and the low-load condition are met, after starting the circulation pump 34, the following steps are also included:

[0167] S411. When the low load condition is met, the temperature control system enters the low load control mode. In the low load control mode, the opening of the secondary expansion valve 22 is first adjusted to gradually reduce the evaporation temperature of the load evaporator 23 until the second termination condition is met. When the second termination condition and the low load condition are met, the second regulating expansion valve 17 is opened.

[0168] S412. After opening the second regulating expansion valve, determine whether the temperature control system meets the normal conditions based on the current status data. If not, start the circulation pump 34.

[0169] The second regulating expansion valve 17 can be a liquid-injection electronic expansion valve. When the second regulating expansion valve 17 is open, the second bypass 16 diverts the refrigerant in the main circuit of the primary refrigeration loop L1, which reduces the refrigerant content flowing through the evaporator-condenser 14, reduces the condensing capacity of the secondary refrigerant, and thus reduces the liquid refrigerant content entering the load evaporator 23, improving the problem of liquid carryover in the return gas of the secondary compressor 21. At the same time, the diverted refrigerant, after being cooled by the second regulating expansion valve 17, flows back to the return gas end of the primary compressor 11, increasing the return gas superheat of the primary compressor 11 (referred to as primary return gas superheat) and the return gas pressure of the primary compressor 11 (referred to as primary return gas pressure), preventing liquid carryover in the return gas of the primary compressor 11.

[0170] After the set time for opening the second regulating expansion valve 17, once the system is running relatively stably, the status data of the secondary compressor 21 can be used to determine whether the temperature control system meets the normal conditions. If the normal conditions are not met, it means that opening the second regulating expansion valve 17 cannot completely solve the low load problem of the temperature control system. At this time, the circulating pump 34 is activated to intervene in the temperature of the return gas refrigerant through the cooling circuit L and the heat exchange module 30.

[0171] Specifically, the circulation pump 34 is turned on, and the heat exchange module 30 is started to heat the return gas refrigerant. Before the liquid refrigerant enters the secondary compressor 21, the liquid components in the return gas refrigerant are heated to evaporate into gas, thus completely solving the problem of liquid carrying in the return gas of the secondary compressor 21.

[0172] At this time, when the temperature control system is in low-load control mode, if the regulation of the secondary expansion valve 22 cannot completely solve the problem of liquid carryover in the return gas of the secondary compressor 21, the temperature of the return refrigerant of the secondary compressor 21 is first regulated by the second regulating expansion valve 17. Only when the second regulating expansion valve 17 also cannot completely solve the problem of liquid carryover in the return gas is the circulation pump 34 started. The regulation of the secondary expansion valve 22 and the second regulating expansion valve 17 are both passive and low-power regulation methods, and their limited use can avoid increasing energy consumption. Starting the circulation pump 34 and using the heat exchange module 30 to regulate the refrigerant temperature of the secondary compressor 21 through the cooling circuit L is an active and high-energy-consuming regulation method. At this time, in low-load mode, the three-stage progressive anti-liquid carryover control method of controlling the secondary expansion valve 22, the second regulating expansion valve 17, and the circulation pump 34 sequentially can maximize energy saving while ensuring system safety.

[0173] In some embodiments, the temperature control system further includes an electric heater (not shown) for regulating the load temperature.

[0174] Reference Figure 7 In S411, the opening of the secondary expansion valve 22 is adjusted to gradually reduce the evaporation temperature of the load evaporator 23 until the second termination condition is met, including:

[0175] S4111. Adjust the opening of the secondary expansion valve 22 at set intervals so that the evaporation temperature of the load evaporator 23 decreases by a set temperature each time.

[0176] For example, the opening of the secondary expansion valve 22 is adjusted every 1 to 5 minutes, so that the evaporation temperature of the load evaporator 23 decreases by 1 to 2 degrees Celsius after each adjustment.

[0177] S4112. After each adjustment, after the evaporation temperature of the load evaporator 23 has stabilized for a set time, determine whether the temperature control system meets the second termination condition. The second termination condition is that the duty cycle decay of the electric heater exceeds the decay threshold or the current evaporation temperature of the load evaporator 23 reaches the lower limit of the evaporation temperature. The duty cycle decay of the electric heater is the percentage of the duty cycle decay value to the default duty cycle. The duty cycle decay value is equal to the default duty cycle minus the current duty cycle of the electric heater.

[0178] After each adjustment, the evaporation temperature of the load evaporator 23 is acquired multiple times. Once the evaporation temperature remains stable for a set time (e.g., 30s to 1min), indicating that the system is operating stably, it is determined whether the temperature control system meets the second termination condition. Specifically, the degree of duty cycle decay of the electric heater and the current evaporation temperature are acquired.

[0179] The electric heater is used to heat the load. When the temperature control system is equipped with an electric heater, the electric heater works in conjunction with the secondary refrigeration module 20 to counteract heat and cold, jointly regulating the load temperature. At the set production temperature, the electric heater is usually configured with a default duty cycle, and the electric heater operates according to the default duty cycle. During the process of the temperature control system adjusting the evaporation temperature by controlling the secondary expansion valve 22, the cooling effect of the load evaporator 23 on the load decreases. In order to maintain the load temperature balance, the electric heater will also dynamically adjust, continuously reducing its duty cycle, that is, the duty cycle of the electric heater decays, in order to reduce heat output.

[0180] The duty cycle decay value of the electric heater is equal to the default duty cycle minus the current duty cycle. The decay threshold is used to limit the degree of duty cycle decay of the electric heater, preventing excessive decay that could cause unstable load temperature and affect test results. Optionally, the decay threshold is 3% to 6%, specifically 3%, 4%, 5%, 6%, or any adjacent values. The lower limit of the evaporation temperature of the load evaporator 23 (e.g., -80℃ to -50℃) is used to limit the degree of temperature reduction, preventing negative effects such as frost formation on the surface of the load evaporator 23 and reduced compressor efficiency.

[0181] S4113. If the second termination condition is met, stop adjusting the opening of the second expansion valve.

[0182] Therefore, when the duty cycle decay value of the electric heater reaches the decay threshold or the evaporation temperature reaches the lower limit of the evaporation temperature, stop adjusting the opening of the secondary expansion valve 22 to avoid other adverse consequences.

[0183] In one embodiment, an electric heater is disposed at the load evaporator 23. Installing the electric heater at the load evaporator 23 achieves close spatial coupling between the heat source and the cold source, reduces control hysteresis, prevents frost formation on the load evaporator 23, and simplifies the control logic.

[0184] Understandably, when the temperature control system meets the second termination condition and during the process of adjusting the opening of the secondary expansion valve 22, the temperature control system determines whether it meets the conditions for being in the normal control mode based on the current status data. If it does, the adjustment is stopped and the current parameters are maintained.

[0185] In some embodiments, continue to refer to Figure 7 In S411, opening the second regulating expansion valve 17 includes:

[0186] S4114. Obtain the first-stage discharge superheat and the first-stage return gas pressure of the first-stage compressor 11.

[0187] The method for obtaining the primary return gas pressure of the primary compressor 11 can refer to the method for obtaining the secondary return gas pressure described above. The primary exhaust superheat is determined by the difference between the primary exhaust temperature and the saturated evaporation temperature corresponding to the primary exhaust pressure. The primary exhaust temperature can be obtained through a temperature sensor installed on the exhaust pipe of the primary compressor 11, and the primary exhaust pressure can be obtained through a pressure sensor installed on the exhaust pipe of the primary compressor 11. The saturated evaporation temperature corresponding to the primary refrigerant is retrieved based on the measured primary exhaust pressure; the difference between the primary exhaust temperature and the saturated evaporation temperature is the primary exhaust superheat.

[0188] It is worth noting that as the opening of the secondary expansion valve 22 decreases, the refrigerant content in the load evaporator 23 decreases, causing a drop in the primary return gas pressure of the secondary compressor 21. Simultaneously, due to the reduced cooling capacity demand of the secondary refrigeration module 20, the heat transfer from the secondary refrigerant to the primary refrigerant at the evaporator-condenser decreases. This means the heat load on the evaporator-condenser 14 in the primary refrigeration circuit L1 decreases, making the primary compressor 11 prone to liquid carryover in the return gas, resulting in abnormal primary discharge superheat and primary return gas pressure. In some cases, when the heat load of the primary refrigerant decreases, the temperature control system can adapt to the change in heat load by reducing the opening of the primary expansion valve 13. However, while the adjustment effect of the primary expansion valve 13 is effective, the adjustment speed is slow. Therefore, in this embodiment, the problem of liquid carryover in the return gas of the primary compressor 11 is improved by adjusting the second regulating expansion valve 17, thereby improving the adjustment effect and efficiency. Of course, the problem of liquid carryover in the return gas of the primary compressor 11 can also be improved by combining the adjustment of the primary expansion valve 13 and the second regulating expansion valve 17.

[0189] S4115. If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first-stage return gas pressure is lower than the first return pressure critical value, control the second regulating expansion valve to work according to the first condition or the second condition. The first condition is to control the opening of the second regulating expansion valve 17 to the set opening, and when the first-stage return gas pressure is greater than the second return pressure critical value, close the second regulating expansion valve 17. The second condition is to control the opening of the second regulating expansion valve 17 according to the opening matched with the target production temperature of the temperature control system.

[0190] The first back pressure critical value is lower than the second back pressure critical value. Specifically, the first back pressure critical value is taken within the range of [25 kPa, 35 kPa], and the second back pressure critical value is taken within the range of [45 kPa, 60 kPa]. The first back pressure critical value can be 25 kPa, 30 kPa, 35 kPa, or any value between any two adjacent values. The second back pressure critical value can be 45 kPa, 50 kPa, 55 kPa, 60 kPa, or any value between any two adjacent values. The lower limit of exhaust superheat can be taken within the range of [25℃, 30℃], specifically 25℃, 26℃, 28℃, 30℃, or any value between any two adjacent values.

[0191] When the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first back pressure critical value is lower than the first back pressure critical value, it indicates that the first-stage compressor 11 has liquid in the return gas. At this time, the adjustment and control should be performed according to the first condition or the second condition.

[0192] The first condition is to control the opening degree of the second regulating expansion valve 17 to the set opening degree, and to close the second regulating expansion valve when the first-stage return gas pressure is greater than the second return pressure critical value.

[0193] That is, the opening degree of the second regulating expansion valve 17 is directly set to a fixed degree. This fixed opening degree can be between 15% and 25%, such as 15%, 18%, 20%, 23%, 25%, and any values ​​between adjacent values. If the fixed opening degree of the second regulating expansion valve 17 is too large, it will seriously affect the refrigeration efficiency; if the fixed opening degree of the second regulating expansion valve 17 is too small, it will not be effective in solving the liquid carryover problem of the first-stage compressor 11. When the fixed opening degree is within the range of 15%-25%, the liquid carryover problem can be solved while maintaining the refrigeration efficiency of the temperature control system.

[0194] As the second regulating expansion valve 17 opens, the return gas pressure of the first-stage compressor 11 gradually increases. When the first-stage return gas pressure exceeds the second return pressure critical value, the liquid carryover problem in the return gas of the first-stage compressor 11 is resolved, and the second regulating expansion valve 17 closes to prevent overheating of the return gas in the first-stage compressor 11. Controlling the operation of the second regulating expansion valve 17 with a fixed opening at this time greatly simplifies the control strategy.

[0195] The second condition is to control the opening of the second regulating expansion valve according to the opening degree matched to the target production temperature of the temperature control system. The target production temperature is a set value used to characterize the target temperature required by the load. Controlling the operation of the second regulating expansion valve 17 according to the opening degree matched to the target production temperature allows the actual production temperature of the temperature control system to approach the target production temperature infinitely. The target production temperature is the ultimate goal of the temperature control system. At this time, adjusting the opening degree of the second regulating expansion valve 17 with the target production temperature as the target is the most efficient and reliable control strategy.

[0196] S4116. If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first regulating expansion valve 25 is closed, if the actual production temperature of the temperature control system is lower than its target production temperature, the opening of the second regulating expansion valve shall be controlled according to the opening degree matched with the target production temperature of the temperature control system.

[0197] When the sorting machine is under ultra-low temperature testing, the first regulating expansion valve 25 is closed, and the temperature control system operates at high cooling capacity. Under these conditions, if the test temperature is significantly increased (e.g., from -55℃ to -10℃), the required cooling capacity decreases drastically, and the heat load on the evaporator-condenser 14 decreases significantly, leading to severe liquid carryover in the primary compressor 11. At this point, the opening of the second regulating expansion valve is controlled according to the opening degree matched to the target production temperature of the temperature control system to quickly reduce liquid carryover in the primary compressor 11, thereby preventing primary compressor 11 malfunction.

[0198] In one specific embodiment, in S4116 and S4115, controlling the opening of the second regulating expansion valve 17 according to the opening degree matched to the target production temperature of the temperature control system includes:

[0199] a1. Among the multiple production temperature ranges set by the self-defined temperature increment, the production temperature range where the target production temperature is located is determined as the target production temperature range.

[0200] a2. The second regulating expansion valve 17 is controlled to operate according to the set opening degree associated with the target production temperature range, wherein the set opening degree associated with the higher the temperature of the production temperature range is is smaller.

[0201] Specifically, multiple production temperature ranges are pre-set, and each production temperature range corresponds to a preset valve opening degree. Table 2 records the five pre-set production temperature ranges and their preset valve opening degrees in the example. The opening degrees are set decreasingly from 1 to 4, with opening degree 4 > 0. The temperatures ST0 to ST3 are set increasingly. For example, the five production temperature ranges are divided according to the production temperature range of -65℃ to 150℃, namely <-45℃, [-45℃, -20℃), [-20℃, -10℃), [-10℃, 0℃), and ≥0℃. The opening degree corresponding to these five production temperature ranges is gradually reduced according to a preset percentage (e.g., 5% to 10%) until it reaches 0.

[0202] Table 2

[0203] Production temperature Valve opening <ST0 Opening degree 1 [ST0, ST1) Opening degree 2 [ST1, ST2) Opening 3 [ST2, ST3) Opening 4 ≥ST3 0

[0204] After obtaining the target production temperature, the target production temperature range is determined from multiple production temperature ranges, and the valve opening corresponding to this target production temperature range is determined. Then, the second regulating expansion valve 17 is controlled to open at the set valve opening. For example, if the current target production temperature is in the production temperature range [ST1, ST2), the opening of the second regulating expansion valve 17 is controlled at opening 3.

[0205] The higher the production temperature, the higher the discharge and return gas temperatures of the secondary compressor 21. This results in a greater demand for cooling capacity from the primary refrigeration circuit L1 at the evaporator-condenser 14, and consequently, a higher refrigerant temperature returning to the primary compressor 11. To prevent excessively high return gas temperatures from the primary compressor 11, the opening of the second regulating expansion valve 17 needs to be reduced. Therefore, the higher the production temperature range, the smaller the set opening.

[0206] At this time, the production temperature is divided into multiple production temperature ranges, and the opening of the second regulating expansion valve 17 is controlled according to the production temperature range, so that the opening of the second regulating expansion valve 17 is more matched with the target production temperature, so that the actual production temperature approaches the target production temperature as quickly as possible, and the regulation efficiency of the temperature control system is accelerated.

[0207] In some embodiments, a cooling valve for regulating flow rate is provided on the cooling circuit. When the circulating pump is started, the method further includes controlling the opening degree of the cooling valve based on the difference between the actual outlet temperature and the set outlet temperature of the cooling circuit; the larger the difference, the larger the opening degree of the cooling valve, and vice versa.

[0208] In low-load control mode, the outlet set temperature is typically required to be higher than the temperature of the heat exchange medium to ensure that the cooling water absorbs heat from the heat exchange medium during heat exchange. Since cooling circuit L2 exchanges heat with the primary condenser 12, the cooling water absorbs heat from the primary refrigerant. This absorbed heat can be used to heat the heat exchange medium, thereby improving heat utilization. In this case, the outlet set temperature of cooling circuit L2 can be set relatively low, such as 20℃~25℃.

[0209] In overload control mode, since the cooling water needs to cool both the heat exchange medium and the primary refrigerant at the same time, the outlet set temperature in overload control mode is usually higher than that in low load control mode, such as 40℃~60℃.

[0210] In both overload and low-load control modes, when the circulating pump 34 is activated, the heat exchange circuit 33 is engaged to achieve heat exchange between the cooling circuit L2 and the return gas refrigerant of the secondary compressor 11. In overload control mode, the heat exchange medium in the heat exchange circuit 33 absorbs heat from the return gas refrigerant and heats up, releasing heat to the cooling water in the cooling circuit L2, thus enabling the cooling water to perform a cooling function. In low-load control mode, the heat exchange medium in the heat exchange circuit 33 heats the liquid phase in the return gas refrigerant and cools it down, while also absorbing heat from the cooling water in the cooling circuit L2, thus enabling the cooling water to perform a heating function.

[0211] In one embodiment, the primary condenser 12 serves as a heat exchange section 32, thermally coupling the cooling circuit L2 with both the heat exchange circuit 33 and the primary refrigeration circuit L1. Specifically, the primary condenser 12 has a first flow path and a second flow path internally, which are independently configured. The first flow path is located in the primary refrigeration circuit L1, and the second flow path is located in the heat exchange circuit 33. The cooling circuit L2 is wound around the outside of the primary condenser 12, and the flow rate of cooling water in the cooling circuit L2 is adjusted by controlling the opening of the cooling valve.

[0212] In overload control mode, the flow rate of the cooling valve is increased to increase the cooling water flow rate, thereby meeting the cooling requirements of the high-temperature heat exchange medium and the high-temperature primary refrigerant. In low-load control mode, the flow rate of the cooling valve is reduced, and the temperature at the outlet of cooling circuit L2 is controlled to be higher than the temperature of the heat exchange medium at the inlet of the second flow path. This allows the cooling water in cooling circuit L2 to both cool the high-temperature primary refrigerant in the first flow path and heat the low-temperature heat exchange medium in the second flow path. In this way, the two independent flow paths, primary refrigeration circuit L1 and heat exchange circuit 33, are integrated into the same heat exchanger, saving space and piping, and making it more economical.

[0213] In another embodiment, the heat exchange section 32 may also include two second heat exchangers (not shown). In the cooling circuit L2, one second heat exchanger is arranged downstream of the primary condenser 12, and the other second heat exchanger is arranged upstream of the primary condenser 12. In the heat exchange circuit 33, the two second heat exchangers are connected in parallel and are not simultaneously activated. Specifically, a switching valve is provided on each of the parallel flow paths containing the two second heat exchangers, and the opening and closing of the switching valves controls the activation or deactivation of the parallel flow paths containing each second heat exchanger.

[0214] The temperature control system proposed in this application includes the technical features described in the above embodiments, which will not be repeated here. Furthermore, the temperature control system is capable of executing the control method of the temperature control system in the above embodiments.

[0215] In addition, this application also proposes a testing device, which includes a temperature control system and a testing terminal. The temperature control system is used to adjust the temperature of the testing terminal. The temperature control system can execute the control method described in the above embodiments, or it can be the temperature control system described in the above embodiments.

[0216] In one embodiment, the test terminal includes a pressure connector, which serves as a load evaporator 23 connected to the secondary refrigeration circuit L3. In practical applications, the load can be a chip that contacts the pressure connector.

[0217] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0218] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are specific and detailed, they should not be construed as limiting the scope of this patent application. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A control method for a temperature control system, characterized in that, The temperature control system includes a primary refrigeration module, a secondary refrigeration module, a heat exchange module, and a cooling circuit. The primary refrigeration module includes a primary compressor, a primary condenser, a primary expansion valve, and an evaporator-condenser arranged sequentially in the primary refrigeration circuit. The cooling circuit is thermally coupled to the primary refrigeration circuit via the primary condenser. The secondary refrigeration module includes a secondary compressor, a secondary expansion valve, and a load evaporator arranged sequentially in the secondary refrigeration circuit. The primary and secondary refrigeration modules are thermally coupled through the evaporator-condenser. The heat exchange module includes a first heat exchanger, a heat exchange section, a heat exchange circuit, and a circulating pump. The circulating pump is located in the heat exchange circuit. The first heat exchanger thermally couples the heat exchange circuit and the secondary refrigeration circuit, and is arranged in the secondary refrigeration circuit between the load evaporator and the secondary compressor. The heat exchange circuit is filled with a heat exchange medium. The heat exchange section thermally couples the heat exchange circuit and the cooling circuit. The control method includes: In cooling mode, the status data of the temperature control system is acquired, including the secondary return gas superheat and the secondary exhaust temperature of the secondary compressor. Based on the status data, it is determined whether the temperature control system meets the overload condition or the low load condition. The overload condition is that the secondary return gas superheat exceeds the upper limit of the first return gas superheat and the secondary exhaust temperature exceeds the upper limit of the exhaust temperature. The low load condition is that the secondary return gas superheat is lower than the lower limit of the return gas superheat and the secondary exhaust temperature is lower than the lower limit of the exhaust temperature. When the overload condition is met, the temperature control system is controlled to enter the overload control mode; in the overload control mode, the circulation pump is turned on so that the cooling circuit indirectly cools the return gas refrigerant of the secondary compressor through the heat exchange circuit. When the low-load condition is met, the temperature control system is controlled to enter the low-load control mode; in the low-load control mode, the circulation pump is turned on so that the cooling circuit indirectly heats the return gas refrigerant of the secondary compressor through the heat exchange circuit.

2. The control method for the temperature control system according to claim 1, characterized in that, In the overload control mode, activating the circulation pump includes: In the overload control mode, the opening of the secondary expansion valve is first adjusted to gradually increase the evaporation temperature of the load evaporator until the first termination condition is met; when the first termination condition and the overload condition are met, the circulation pump is started.

3. The control method according to claim 2, characterized in that, The adjustment of the opening of the secondary expansion valve to gradually increase the evaporation temperature of the load evaporator until the first termination condition is met includes: The opening of the secondary expansion valve is adjusted at set intervals so that the evaporation temperature of the load evaporator rises to the set temperature each time. After each adjustment, when the evaporation temperature of the load evaporator stabilizes for a set time, it is determined whether the temperature control system meets the first termination condition. The first termination condition is that the current discharge pressure of the secondary compressor exceeds the upper limit of the discharge pressure or the current evaporation temperature of the load evaporator reaches the upper limit of the evaporation temperature. If the first termination condition is met, stop adjusting the opening of the secondary expansion valve.

4. The control method according to claim 2, characterized in that, The secondary refrigeration module further includes a first bypass, one end of which is connected to the outlet end of the evaporator-condenser, and the other end is connected to the return gas end of the secondary compressor. A first regulating expansion valve is provided on the first bypass. When the first termination condition and the overload condition are met, the circulation pump is started, including: When the first termination condition and the overload condition are met, the current secondary return gas superheat of the secondary compressor is obtained. If the current secondary return gas superheat exceeds the upper limit of the second return gas superheat, the circulation pump is turned on, and the upper limit of the second return gas superheat is greater than the upper limit of the first return gas superheat. If the current secondary return gas superheat does not exceed the upper limit of the second return gas superheat, the first regulating expansion valve is opened.

5. The control method according to claim 4, characterized in that, If the current return gas superheat exceeds the upper limit of the second return gas superheat, after starting the circulation pump, the method further includes: Obtain the current status data of the temperature control system, and determine whether the temperature control system meets the normal conditions based on the current status data. The normal conditions are that either the secondary return gas superheat or the secondary exhaust temperature is within the allowable range. If the aforementioned conventional conditions are not met, the first regulating expansion valve will be opened.

6. The control method according to claim 5, characterized in that, The opening of the first regulating expansion valve includes: The current secondary exhaust temperature is acquired multiple times. Each time the current secondary exhaust temperature is acquired, the exhaust temperature range in which the current secondary exhaust temperature is located is determined as the target exhaust temperature range from multiple exhaust temperature ranges with decreasing temperature settings and all temperature values ​​not lower than the upper limit of exhaust temperature. The first regulating expansion valve is controlled to work according to the set opening degree associated with the target exhaust temperature range until the current secondary exhaust temperature does not exceed the upper limit of exhaust temperature. The higher the temperature in the exhaust temperature range, the greater the associated set opening degree.

7. The control method according to claim 1, characterized in that, In the low-load control mode, starting the circulation pump includes: In the low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met; when the second termination condition and the low-load condition are met, the circulation pump is turned on.

8. The control method according to claim 7, characterized in that, The primary refrigeration module also includes a second bypass, one end of which is connected to the discharge end of the primary compressor and the other end of which is connected to the return end of the primary compressor. A second regulating expansion valve is provided on the second bypass. In the low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met. When the second termination condition and the low-load condition are met, the circulation pump is started, including: In the low-load control mode, the opening of the secondary expansion valve is first adjusted to gradually reduce the evaporation temperature of the load evaporator until the second termination condition is met. When the second termination condition and the low load condition are met, the second regulating expansion valve is opened. After opening the second regulating expansion valve, determine whether the temperature control system meets the normal conditions based on the current status data. If not, start the circulation pump.

9. The control method according to claim 7, characterized in that, The temperature control system also includes an electric heater, which is used to regulate the load temperature; Adjust the opening of the secondary expansion valve to gradually reduce the evaporation temperature of the loaded evaporator until the second termination condition is met, including: The opening of the secondary expansion valve is adjusted at set intervals so that the evaporation temperature of the load evaporator drops by the set temperature each time. After each adjustment, after the evaporation temperature of the load evaporator stabilizes for a set time, it is determined whether the temperature control system meets the second termination condition. The second termination condition is that the duty cycle decay of the electric heater exceeds the decay threshold or the current evaporation temperature of the load evaporator reaches the lower limit of the evaporation temperature. If the second termination condition is met, stop adjusting the opening of the secondary expansion valve.

10. The control method according to claim 8, characterized in that, The opening of the second regulating expansion valve includes: Obtain the first-stage discharge superheat and the first-stage return pressure of the first-stage compressor; If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first-stage return gas pressure is lower than the first back pressure critical value, the second regulating expansion valve is controlled to operate according to either the first condition or the second condition. The first condition is to control the opening of the second regulating expansion valve to a set opening, and to close the second regulating expansion valve when the first-stage return gas pressure is greater than the second back pressure critical value, wherein the first back pressure critical value is less than the second back pressure critical value. The second condition is to control the opening of the second regulating expansion valve according to the opening matched to the target production temperature of the temperature control system. If the first-stage exhaust superheat is lower than the lower limit of exhaust superheat and the first regulating expansion valve is closed, and if the actual production temperature of the temperature control system is lower than its target production temperature, then the opening degree of the second regulating expansion valve is controlled according to the opening degree matched to the target production temperature of the temperature control system.

11. The control method according to claim 10, characterized in that, Controlling the opening degree of the second regulating expansion valve according to the opening degree matched to the target production temperature of the temperature control system includes: Among the multiple production temperature ranges set by the self-defined temperature increment, the production temperature range in which the target production temperature is located is determined as the target production temperature range; The second regulating expansion valve is controlled to operate according to a set opening degree associated with the target production temperature range, wherein the set opening degree associated with the higher the temperature of the production temperature range is is smaller.

12. The control method according to claim 1, characterized in that, The cooling circuit is equipped with a cooling valve for regulating the flow rate; Starting the circulation pump also includes: The opening degree of the cooling valve is controlled according to the difference between the actual outlet temperature and the set outlet temperature of the cooling circuit. The larger the difference, the larger the opening degree of the cooling valve, and vice versa.

13. A temperature control system, characterized in that, include: The primary refrigeration module includes a primary compressor, a primary condenser, a primary expansion valve, and an evaporator-condenser arranged sequentially in the primary refrigeration circuit. The cooling circuit is thermally coupled to the primary refrigeration circuit via the primary condenser. The secondary refrigeration module includes a secondary compressor, a secondary expansion valve, and a load evaporator arranged sequentially in the secondary refrigeration circuit. The primary refrigeration module and the secondary refrigeration module are thermally coupled through the evaporator-condenser. A heat exchange module includes a first heat exchanger, a heat exchange section, a heat exchange circuit, and a circulating pump. The circulating pump is located in the heat exchange circuit. The first heat exchanger is thermally coupled to the heat exchange circuit and the secondary refrigeration circuit, and is arranged on the secondary refrigeration circuit between the load evaporator and the secondary compressor. The heat exchange circuit is filled with a heat exchange medium. The heat exchange section is thermally coupled to the heat exchange circuit and the cooling circuit.

14. The temperature control system according to claim 13, characterized in that, The secondary refrigeration module also includes a first bypass, one end of which is connected to the outlet end of the evaporator-condenser, and the other end is connected to the return gas end of the secondary compressor. A first regulating expansion valve is provided on the first bypass. And / or, The primary refrigeration module further includes a second bypass, one end of which is connected to the discharge end of the primary compressor, and the other end of which is connected to the return end of the primary compressor. A second regulating expansion valve is provided on the second bypass; and / or, The temperature control module includes an electric heater disposed on the load evaporator; and / or The primary condenser serves as the heat exchange unit, thermally coupling the cooling circuit with both the heat exchange circuit and the primary refrigeration circuit.

15. A testing device, characterized in that, The device includes a temperature control system and a test terminal, wherein the temperature control system is used to adjust the temperature of the test terminal; wherein the temperature control system performs the control method as described in any one of claims 1 to 12.

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