Refrigerating system for freezing and thawing machine and control method and control device of refrigerating system

Abstract

The invention relates to the technical field of refrigeration, and discloses a refrigeration system for a freeze thawing machine, comprising: a refrigerant circulation loop comprising a loop formed by sequentially connecting a compressor, a condenser, a first heat regenerator, a throttling device and an evaporator through a refrigerant pipeline, and the refrigerant circulation loop is filled with a plurality of refrigerants with different boiling points; the air return flow path switching assembly is arranged between the outlet of the evaporator and the air suction port of the compressor and is configured to selectively communicate with the first air return branch or the second air return branch; wherein the first air return branch does not pass through the first heat regenerator; and the second air return branch passes through the second flow path of the first heat regenerator and exchanges heat with the first flow path of the first heat regenerator. The refrigerating system has the low-temperature refrigerating capacity and the high-temperature operation stability within the wide-temperature-zone range, and the actual requirement of the freezing and thawing machine for precise temperature control of the wide-temperature-zone range is met. The invention further discloses a control method and device for the refrigerating system of the freezing and thawing machine.

Description

Technical Field

[0001] This application relates to the field of refrigeration system technology, for example to a refrigeration system for a freeze-thaw machine and its control method and control device. Background Technology

[0002] Currently, cryo-thaw machines are widely used in the biomedical field. Commonly used ultra-low temperature cryo-thaw machines on the market typically cover a temperature range of -82℃ to 40℃ to meet the needs of the entire process of biological sample preservation, from deep cryopreservation to rapid thawing. Therefore, cryo-thaw machines not only need extremely low cooling capacity but also precise temperature control over a wide temperature range. Based on this, a regenerative refrigeration cycle system has been proposed, utilizing the advantages of each component of a non-azeotropic refrigerant in different temperature zones to achieve both low temperatures and high cooling capacity.

[0003] In the process of implementing the embodiments of this disclosure, at least the following problems were found in the related art: While the relevant technologies can ensure stable operation and sufficient cooling capacity at lower temperatures, the evaporator return gas temperature will significantly increase under high-temperature conditions. If the high-temperature return gas continues to flow through the regenerator and exchange heat with the refrigerant at the condenser outlet, the regenerator will reverse-heat the liquid refrigerant at the condenser outlet. This not only reduces the subcooling of the refrigerant at the condenser outlet, but in severe cases, it can even cause low-boiling-point components in the non-azeotropic refrigerant mixture to vaporize prematurely before entering the throttling device, resulting in an abnormal increase in the dryness of the refrigerant at the condenser outlet. This, in turn, disrupts the normal operation of the throttling device and affects the system's operational stability.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this application, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To provide a basic understanding of some aspects of the disclosed embodiments, a brief summary is given below. This summary is not intended as a general commentary, nor is it intended to identify key / important components or describe the scope of protection of these embodiments, but rather as a prelude to the detailed description that follows.

[0006] This disclosure provides a refrigeration system and its control method and device for a freeze-thaw machine, enabling the refrigeration system to balance low-temperature cooling capacity and high-temperature operating stability over a wide temperature range, thus meeting the actual needs of the freeze-thaw machine for precise temperature control over a wide temperature range.

[0007] In some embodiments, the refrigeration system includes: a refrigerant circulation loop, comprising a compressor, a condenser, a first regenerator, a throttling device, and an evaporator connected sequentially via refrigerant piping, wherein the refrigerant circulation loop is filled with a variety of refrigerants with different boiling points; and a return gas path switching component, disposed between the outlet of the evaporator and the suction port of the compressor, configured to selectively connect a first return gas branch or a second return gas branch; wherein the first return gas branch connects the outlet of the evaporator and the suction port of the compressor, and does not pass through the first regenerator; the second return gas branch connects the outlet of the evaporator and the suction port of the compressor, and passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator.

[0008] In some embodiments, the control method includes: acquiring the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine; and controlling the connection state of the return airflow path switching component based on the load temperature and the ambient temperature.

[0009] In some embodiments, the control device includes a processor and a memory storing program instructions, the processor being configured to execute the control method described above for a refrigeration system for a freeze-thaw machine when the program instructions are executed.

[0010] The refrigeration system and control method and control device for freeze-thaw machines provided in this disclosure can achieve the following technical effects: This embodiment fills the refrigerant circulation loop with multiple refrigerants of different boiling points to form a non-azeotropic mixture. A return gas path switching component is used to construct a first return gas branch that bypasses the first regenerator and a second return gas branch that passes through the first regenerator. This allows the evaporator return gas to selectively switch between different return gas paths according to operating conditions, thereby preventing high-temperature return gas from participating in regenerative heat exchange under high-temperature conditions. Therefore, when the freeze-thaw unit is operating at high temperatures, this embodiment allows the high-temperature return gas from the evaporator outlet to flow directly back to the compressor, preventing reverse heat exchange with the refrigerant at the condenser outlet. This avoids the problem of reduced subcooling of the refrigerant at the condenser outlet and premature vaporization of low-boiling-point components in the non-azeotropic mixture, effectively maintaining a stable liquid phase state of the refrigerant at the throttling device inlet, ensuring the reliability of the throttling process and the operational stability of the refrigeration system. Meanwhile, the embodiments disclosed herein achieve effective heat recovery by passing the return air through the first regenerator under low-temperature conditions, which can give full play to the refrigeration advantages of non-azeotropic mixed refrigerant in the low-temperature range, so that the refrigeration system can take into account both low-temperature refrigeration capacity and high-temperature operation stability in a wide temperature range, and meet the actual needs of freeze-thaw machines for precise temperature control in a wide temperature range.

[0011] The above general description and the description below are exemplary and illustrative only and are not intended to limit this application. Attached Figure Description

[0012] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations and drawings do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are shown as similar elements. The drawings are not to be scaled. And wherein: Figure 1 This is a schematic diagram of a refrigeration system for a freeze-thaw machine provided in an embodiment of this disclosure; Figure 2 This is a schematic diagram of another refrigeration system for a freeze-thaw machine provided in an embodiment of this disclosure; Figure 3 This is a schematic diagram of another refrigeration system for a freeze-thaw machine provided in an embodiment of this disclosure; Figure 4 This is a schematic diagram of another refrigeration system for a freeze-thaw machine provided in an embodiment of this disclosure; Figure 5 This is a schematic diagram of a control method for a refrigeration system of a freeze-thaw machine provided in an embodiment of this disclosure; Figure 6 This is a schematic diagram of another control method for a refrigeration system of a freeze-thaw machine provided in an embodiment of this disclosure; Figure 7 This is a schematic diagram of a control device for a refrigeration system of a freeze-thaw machine provided in an embodiment of this disclosure.

[0013] Figure label: 10: Compressor; 20: Condenser; 30: First regenerator; 40: Throttling device; 50: Evaporator; 60: Second regenerator; 70: Gas-liquid separator; 80: Expansion tank; 90: Dryer filter; 100: Refrigerant circulation loop; 200: Return gas path switching assembly; 201: First return gas branch; 202: Second return gas branch; 203: Third return gas branch; 300: Component concentration adjustment branch; 401: First control valve; 402: Second control valve Valve; 403: Third control valve; 404: Fourth control valve; 405: Fifth control valve; 501: First check valve; 502: Second check valve; 601: First sensor; 602: Second sensor; 603: Third sensor; 604: Fourth sensor; 700: Heating device; 800: Housing; 900: Control device for the refrigeration system of the freeze-thaw machine; 901: Processor; 902: Memory; 903: Communication interface; 904: Bus. Detailed Implementation

[0014] To provide a more detailed understanding of the features and technical content of the embodiments of this disclosure, the implementation of the embodiments of this disclosure will be described in detail below with reference to the accompanying drawings. The accompanying drawings are for illustrative purposes only and are not intended to limit the embodiments of this disclosure. In the following technical description, for ease of explanation, several details are used to provide a full understanding of the disclosed embodiments. However, one or more embodiments may still be implemented without these details. In other cases, well-known structures and devices may be simplified in their depiction to simplify the drawings.

[0015] The terms "first," "second," etc., used in the specification, claims, and accompanying drawings of this disclosure are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such data can be interchanged where appropriate for the embodiments of this disclosure described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion.

[0016] Unless otherwise stated, the term "multiple" means two or more.

[0017] In this embodiment of the disclosure, the character " / " indicates that the objects before and after it are in an "or" relationship. For example, A / B means: A or B.

[0018] The term "and / or" describes an association between objects, indicating that three relationships can exist. For example, A and / or B means: A or B, or A and B.

[0019] The term "correspondence" can refer to an association or binding relationship. The correspondence between A and B means that there is an association or binding relationship between A and B.

[0020] Combination Figure 1 As shown, this disclosure provides a refrigeration system for a freeze-thaw machine, including a refrigerant circulation loop 100 and a return gas path switching assembly 200. The refrigerant circulation loop 100 includes a compressor 10, a condenser 20, a first regenerator 30, a throttling device 40, and an evaporator 50 connected sequentially via refrigerant piping. The refrigerant circulation loop 100 is filled with various refrigerants with different boiling points. The return gas path switching assembly 200 is located between the outlet of the evaporator 52 and the suction port of the compressor 10, and is configured to selectively connect either a first return gas branch 201 or a second return gas branch 202. The first return gas branch 201 connects the outlet of the evaporator 50 and the suction port of the compressor 10, and does not pass through the first regenerator 30. The second return gas branch 202 connects the outlet of the evaporator 50 and the suction port of the compressor 10, and passes through the second flow path of the first regenerator 30 and exchanges heat with the first flow path of the first regenerator 30.

[0021] The refrigeration system for a freeze-thaw machine provided in this embodiment fills the refrigerant circulation loop 100 with multiple refrigerants of different boiling points to form a non-azeotropic mixture. A return gas path switching component 200 is used to construct a first return gas branch 201 that does not pass through the first regenerator 30 and a second return gas branch 202 that does pass through the first regenerator 30. This allows the return gas from the evaporator 50 to selectively switch between different return gas paths according to the operating conditions, thereby preventing high-temperature return gas from participating in heat exchange under high-temperature conditions. Therefore, when the freeze-thaw machine is in a high-temperature operating condition, this embodiment allows the high-temperature return gas from the evaporator 50 outlet to flow directly back to the compressor 10, preventing reverse heat exchange with the refrigerant at the condenser 20 outlet. This avoids the problem of reduced subcooling of the refrigerant at the condenser 20 outlet and premature vaporization of low-boiling-point components in the non-azeotropic mixture, effectively maintaining a stable liquid phase state of the refrigerant at the inlet of the throttling device 40, ensuring the reliability of the throttling process and the operational stability of the refrigeration system. Meanwhile, in the embodiments disclosed herein, effective heat recovery is achieved by the return flow passing through the first regenerator 30 under low-temperature conditions. This can fully leverage the refrigeration advantages of the non-azeotropic mixed refrigerant in the low-temperature range, enabling the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range, thus meeting the actual needs of freeze-thaw machines for precise temperature control over a wide temperature range.

[0022] Optionally, the refrigerant circulation loop 100 is filled with a first refrigerant and a second refrigerant. The boiling point of the first refrigerant is higher than that of the second refrigerant. Specifically, in some embodiments, the boiling point of the first refrigerant is greater than -30°C, and the boiling point of the second refrigerant is less than -85°C.

[0023] Thus, this embodiment of the present disclosure enables the refrigeration system to operate using a non-azeotropic mixture of refrigerants by charging the refrigerant circulation loop 100 with two refrigerants having different boiling points. The boiling point of the first refrigerant is higher than that of the second refrigerant, allowing the evaporation temperature of the non-azeotropic mixture to be adjusted not only by system pressure but also by regulating the concentration of refrigerant components. Therefore, compared to a single-refrigerant refrigeration system that can only regulate the evaporation temperature through pressure, this embodiment of the present disclosure achieves a wider range of evaporation temperature regulation capabilities. This results in greater adjustment flexibility and operational adaptability of the refrigeration system when operating over a wide temperature range, meeting the practical requirements of freeze-thaw machines for precise temperature control over a wide temperature range.

[0024] Optionally, the return gas path switching assembly 200 includes a first control valve 401 and a second control valve 402. The first control valve 401 is disposed in the first return gas branch 201. The second control valve 402 is disposed in the second return gas branch 202.

[0025] Thus, by setting a first control valve 401 on the first return gas branch 201 and a second control valve 402 on the second return gas branch 202, the return gas path switching component 200 can selectively switch the return gas from the evaporator 50 between the first return gas branch 201 and the second return gas branch 202 by controlling the opening and closing of each return gas branch. Therefore, this embodiment can control whether the return gas from the evaporator 50 passes through the first regenerator 30 to participate in heat exchange according to the operating conditions of the freeze-thaw machine. This avoids high-temperature return gas entering the first regenerator 30 and causing reverse heat exchange of the refrigerant at the outlet of the condenser 20 under high-temperature conditions, while improving the system's refrigeration performance through heat exchange under low-temperature conditions. This allows the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range.

[0026] Optionally, the return gas path switching assembly 200 includes a three-way switching valve. The three-way switching valve is located at the connection between the outlet pipe of the evaporator 50 and the first return gas branch 201 and the second return gas branch 202.

[0027] Thus, this embodiment of the present disclosure provides a three-way switching valve at the outlet pipe of the evaporator 50, connecting the three-way switching valve to the first return gas branch 201 and the second return gas branch 202. This allows the return gas path switching component 200 to selectively switch between the first return gas branch 201 and the second return gas branch 202 through the switching action of the three-way switching valve. Therefore, this embodiment of the present disclosure can control whether the return gas from the evaporator 50 passes through the first regenerator 30 for heat exchange based on the operating conditions of the freeze-thaw machine. This prevents high-temperature return gas from entering the first regenerator 30 and causing reverse heat exchange of the refrigerant at the outlet of the condenser 20 under high-temperature conditions, while improving the system's refrigeration performance through heat exchange under low-temperature conditions. This allows the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range.

[0028] Optionally, combined Figure 2 As shown, the refrigeration system for the freeze-thaw machine also includes a second regenerator 60 and a third return gas branch 203. The first flow path of the second regenerator 60 is located between the exhaust port of the compressor 10 and the inlet of the condenser 20. The third return gas branch 203 connects the outlet of the evaporator 50 and the suction port of the compressor 10, and passes through the second flow path of the second regenerator 60 and exchanges heat with the first flow path of the second regenerator 60.

[0029] Thus, this embodiment of the present disclosure, by setting a second regenerator 60 between the exhaust port of the compressor 10 and the inlet of the condenser 20, and constructing a third return gas branch 203 via the second regenerator 60, allows the return gas from the evaporator 50 to exchange heat with the high-temperature exhaust gas of the compressor 10 before flowing back to the compressor 10. Therefore, this embodiment of the present disclosure can further reheat the return gas from the evaporator 50 under specific operating conditions, increasing the superheat of the return gas and preventing liquid refrigerant entrained in the return gas from directly entering the compressor 10, thereby effectively preventing liquid slugging in the compressor 10 and ensuring the operational safety and reliability of the compressor 10.

[0030] Specifically, one end of the third return gas branch 203 is connected to the pipeline between the second control valve 402 and the inlet of the second flow path of the first regenerator 30, and the other end of the third return gas branch 203 is connected to the pipeline between the first control valve 401 and the suction port of the compressor 10.

[0031] Optionally, the return gas path switching assembly 200 further includes a third control valve 403. The third control valve 403 is located in the third return gas branch 203.

[0032] Thus, by providing a third control valve 403 on the third return gas branch 203, this embodiment of the present disclosure allows the third return gas branch 203 to participate in or exit the return gas cycle in a controlled manner. Therefore, this embodiment of the present disclosure can adjust the degree of return gas reheating according to the operating conditions of the freeze-thaw machine, preventing liquid refrigerant entrained in the return gas from directly entering the compressor 10, thereby effectively preventing liquid slugging in the compressor 10 and ensuring the operational safety and reliability of the compressor 10.

[0033] Optionally, combined Figure 3 As shown, the refrigeration system for the freeze-thaw machine also includes a gas-liquid separator 70 and a component concentration regulating branch 300. The gas-liquid separator 70 is located between the outlet of the condenser 20 and the inlet of the first flow path of the first regenerator 30. The component concentration regulating branch 300 is located between the gas phase outlet of the gas-liquid separator 70 and the outlet of the second flow path of the first regenerator 300, and an expansion tank 80 is installed on the component concentration regulating branch 300.

[0034] Thus, this embodiment of the present disclosure, by setting a gas-liquid separator 70 between the outlet of the condenser 20 and the inlet of the first flow path of the first regenerator 30, and constructing a component concentration adjustment branch 300 leading from the gas phase outlet of the gas-liquid separator 70 to the outlet of the second flow path of the first regenerator 30, enables effective separation of the gas and liquid phases of the refrigerant before it enters the first regenerator 30. Therefore, this embodiment of the present disclosure can specifically guide and adjust the refrigerant of different phases and boiling point components in the refrigerant circulation loop 100, preventing the disorderly entry of gaseous refrigerant into subsequent loops and affecting heat exchange stability. Simultaneously, it provides a structural basis for the dynamic adjustment of the proportions of each component in the non-azeotropic mixed refrigerant, thereby helping to maintain the heat exchange efficiency and operational stability of the system under different operating conditions.

[0035] Optionally, the component concentration adjustment branch further includes a fourth control valve 404 and a fifth control valve 405. The fourth control valve 404 is located between the gas phase outlet of the gas-liquid separator and the inlet of the expansion tank. The fifth control valve 405 is located between the outlet of the expansion tank and the outlet of the second flow path of the first regenerator.

[0036] Thus, by providing a fourth control valve 404 between the gas phase outlet of the gas-liquid separator 70 and the inlet of the expansion tank 80, and a fifth control valve 405 between the outlet of the expansion tank 80 and the second flow path outlet of the first regenerator 30, the on / off state of the component concentration adjustment branch 300 can be precisely controlled. Therefore, according to the operating state of the refrigeration system, this embodiment can selectively involve the expansion tank 80 in the refrigerant storage or release process, achieving dynamic adjustment of the proportion of non-azeotropic mixed refrigerant components in the refrigerant circulation loop 100. This avoids system performance fluctuations caused by refrigerant component imbalance and improves the stability and adaptability of the refrigeration system during operation over a wide temperature range.

[0037] Optionally, the refrigeration system for the freeze-thaw machine also includes a dryer filter 90. The dryer filter 90 is disposed between the outlet of the first flow path of the first regenerator 30 and the throttling device 40.

[0038] Thus, by setting a drying filter 90 between the first flow path outlet of the first regenerator 30 and the throttling device 40, the refrigerant entering the throttling device 40 can be filtered and dried, reducing the impact of moisture and impurities on the throttling process, thereby improving the reliability of the throttling process and ensuring the long-term stable operation of the refrigeration system.

[0039] Optionally, the refrigeration system for the freeze-thaw unit further includes a first one-way valve 501 and a second one-way valve 502. The first one-way valve 501 is located in the first return gas branch 201 and is configured to limit the refrigerant flow in one direction from the outlet of the evaporator 50 to the suction port of the compressor 10. The second one-way valve 502 is located in the second return gas branch 202 and is configured to limit the refrigerant flow in one direction from the outlet of the evaporator 50 to the inlet of the second flow path of the first regenerator 30.

[0040] Thus, by setting a first one-way valve 501 on the first return gas branch 201 and a second one-way valve 502 on the second return gas branch 202, the flow direction of the return gas from the evaporator 50 is limited, so that the refrigerant flows only in the predetermined direction, avoiding backflow or crossflow during the return gas path switching process. This ensures that the adjustment effect of the return gas path switching component 200 is stable and reliable, and reduces the impact of abnormal operating conditions on the operating status of the refrigeration system.

[0041] Optionally, combined Figure 4 As shown, this embodiment of the present disclosure provides a freeze-thaw machine, including: a housing 800, a heating device 700, and the aforementioned refrigeration system for the freeze-thaw machine. The housing 800 has an internal accommodating space. An evaporator 50 is connected to the accommodating space via an air duct. The heating device 700 is disposed inside the air duct.

[0042] By using the freeze-thaw machine provided in this embodiment, the above-mentioned refrigeration system is applied to the freeze-thaw machine, and the evaporator 50 and the heating device 700 work together to enable the freeze-thaw machine to achieve stable and controllable temperature switching during the freezing and thawing stages, thus meeting the actual needs of the freeze-thaw machine for precise temperature control over a wide temperature range.

[0043] Optionally, the freeze-thaw unit also includes a first sensor 601 and a second sensor 602. The first sensor 601 is disposed inside the housing 800 and configured to acquire the load temperature inside the freeze-thaw unit. The second sensor 602 is disposed outside the housing 800 and configured to acquire the ambient temperature outside the freeze-thaw unit.

[0044] Thus, by installing a first sensor 601 inside the housing 800 to obtain the load temperature and a second sensor 602 outside the housing 800 to obtain the ambient temperature, the control device can simultaneously monitor both the internal load status of the freeze-thaw unit and the external environmental conditions. Therefore, based on the comparison between the load temperature and the ambient temperature, this embodiment can determine and adjust the operating strategy of the refrigeration system, providing a reliable data basis for the rational control of the return airflow path switching component 200.

[0045] Optionally, the freeze-thaw unit also includes a third sensor 603 and a fourth sensor 604. The third sensor 603 is located in the discharge line of the compressor 10 and is configured to acquire the discharge pressure of the compressor. The fourth sensor 604 is located in the inlet line of the evaporator 50 and is configured to acquire the inlet temperature of the evaporator.

[0046] Thus, by installing a third sensor 603 on the exhaust pipe of the compressor 10 to obtain the exhaust pressure, and a fourth sensor 604 on the inlet pipe of the evaporator 50 to obtain the evaporator inlet temperature, the control device can monitor the real-time operating parameters of the refrigerant circulation loop 100. Therefore, this embodiment of the present disclosure can precisely monitor the operating status of the refrigeration system, providing a basis for the control of the subsequent component concentration adjustment branch 300, and improving the accuracy and reliability of system operation adjustment.

[0047] Optionally, the freeze-thaw machine further includes a control device 900 for the refrigeration system of the freeze-thaw machine. The control device 900 is installed inside the housing 800 and electrically connected to the return airflow path switching component 200. Thus, embodiments of this disclosure can use the control device 900 to execute corresponding control methods, enabling the refrigeration system to balance low-temperature cooling capacity and high-temperature operational stability over a wide temperature range, meeting the actual requirements of the freeze-thaw machine for precise temperature control over a wide temperature range.

[0048] Based on the aforementioned refrigeration system for freeze-thaw machines, combined with Figure 5 As shown in the embodiments of this disclosure, a control method for a refrigeration system of a freeze-thaw machine is provided, including: S101, the control device acquires the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine.

[0049] S102, the control device controls the connection status of the return airflow path switching component according to the load temperature and ambient temperature.

[0050] The control method for the refrigeration system of a freeze-thaw machine provided in this disclosure acquires the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine, and controls the connection state of the return gas path switching component accordingly. This allows the evaporator return gas to selectively switch between different return gas paths based on the actual operating conditions. Specifically, when the freeze-thaw machine is in a high-temperature condition, the high-temperature return gas from the evaporator outlet flows directly back to the compressor, preventing reverse heat exchange with the refrigerant at the condenser outlet. This avoids the problem of reduced subcooling of the refrigerant at the condenser outlet and premature vaporization of low-boiling-point components in the non-azeotropic refrigerant mixture, thereby effectively maintaining the stable liquid phase state of the refrigerant at the inlet of the throttling device and ensuring the reliability of the throttling process and the operational stability of the refrigeration system. In a low-temperature condition, effective heat recovery is achieved by controlling the return gas flow through the regenerator, which fully utilizes the refrigeration advantages of the non-azeotropic refrigerant mixture in the low-temperature range. This allows the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range, meeting the actual needs of the freeze-thaw machine for precise temperature control over a wide temperature range.

[0051] Optionally, the control device controls the connection state of the first return gas path switching component according to the load temperature and the ambient temperature, including: when the load temperature is greater than or equal to the ambient temperature, the control device controls the return gas path switching component to connect to the first return gas branch, so that the refrigerant at the evaporator outlet does not flow back to the compressor suction port through the first regenerator; or, when the load temperature is less than the ambient temperature, the control device controls the return gas path switching component to connect to the second return gas branch, so that the refrigerant at the evaporator outlet first passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator, and then flows back to the compressor suction port.

[0052] Thus, when the load temperature is greater than or equal to the ambient temperature, this embodiment controls the return gas path switching component to connect to the first return gas branch, allowing the return gas from the evaporator outlet to flow directly back to the compressor without passing through the first regenerator. This avoids reverse heating of the refrigerant at the condenser outlet by the regenerator, preventing a decrease in subcooling or even vaporization, thereby ensuring system operational stability. When the load temperature is less than the ambient temperature, this embodiment controls the return gas path switching component to connect to the second return gas branch, allowing the return gas from the evaporator outlet to pass through the first regenerator and exchange heat with the refrigerant at the condenser outlet. This utilizes the regenerator to increase the subcooling of the refrigerant at the condenser outlet, allowing the non-azeotropic refrigerant mixture to fully utilize its refrigeration performance advantages within this temperature range. Therefore, this embodiment enables the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range, meeting the practical needs of freeze-thaw machines for precise temperature control over a wide temperature range.

[0053] Specifically, the control device controls the return gas path switching component to connect to the first return gas branch, including: the control device opens the first control valve and closes the second control valve to connect to the first return gas branch. Thus, in this embodiment of the present disclosure, by opening the first control valve and closing the second control valve, the evaporator return gas is switched to the branch connected to the first return gas, thereby preventing high-temperature return gas from entering the first regenerator and causing reverse heat exchange of the refrigerant at the condenser outlet.

[0054] Specifically, the control device controls the return gas path switching component to connect to the second return gas branch, including: the control device opens the second control valve and closes the first control valve to connect to the second return gas branch. Thus, in this embodiment of the present disclosure, by opening the second control valve and closing the first control valve, the evaporator return gas can be switched to the second return gas branch, thereby improving the system's cooling performance through heat recovery under low-temperature conditions.

[0055] Optionally, when the load temperature is lower than the ambient temperature, the control method further includes: when the load temperature is lower than a preset load temperature, the control device controls the return gas path switching component to simultaneously connect the second return gas branch and the third return gas branch, so that a portion of the refrigerant at the evaporator outlet passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator, and another portion passes through the second flow path of the second regenerator and exchanges heat with the first flow path of the second regenerator, finally converging and flowing back to the compressor's suction port. Here, the preset load temperature is lower than the ambient temperature.

[0056] Thus, when the load temperature is lower than the ambient temperature and further lower than the preset load temperature, the return gas path switching component of this embodiment controls the simultaneous connection of the second and third return gas branches. This allows a portion of the evaporator return gas to flow through the first regenerator and exchange heat with the refrigerant at the condenser outlet, while another portion flows through the second regenerator and exchanges heat with the compressor exhaust. Finally, both flows converge and return to the compressor. Therefore, when the freeze-thaw unit is operating at extremely low temperatures, this embodiment continuously increases the subcooling of the refrigerant at the condenser outlet and further increases the superheat of the return gas through heat exchange with the compressor exhaust. This ensures that the refrigerant at the evaporator outlet is completely vaporized before entering the compressor, effectively preventing liquid refrigerant from entering the compressor and causing liquid slugging, thus ensuring the safety and reliability of the compressor under deep cryogenic operating conditions.

[0057] Optionally, the preset load temperature can be set according to the type of biological sample. Specifically, the preset load temperature can be set to -40℃ to determine the extremely low temperature conditions under high load. The preset load temperature can also be adjusted according to the user's actual needs, or set to any other reasonable value.

[0058] Specifically, the control device controls the return gas path switching component to simultaneously connect the second return gas branch and the third return gas branch, including: the control device opens the second control valve and the third control valve, and closes the first control valve, so as to simultaneously connect the second return gas branch and the third return gas branch. Thus, in this embodiment of the present disclosure, by opening the second control valve and the third control valve and closing the first control valve, the evaporator return gas can be switched to simultaneously connecting the second return gas branch and the third return gas branch, thereby improving the system's cooling performance through heat recovery under low-temperature conditions and effectively preventing liquid slugging in the compressor.

[0059] Optionally, the control method further includes: when the difference between the load temperature and the target temperature is less than or equal to a preset temperature difference, the control device corrects the connection state of the return airflow path switching component.

[0060] Thus, when the difference between the load temperature and the target temperature is less than or equal to the preset temperature difference, it indicates that the refrigeration system has entered the temperature control stage. The embodiments of this disclosure can correct the connection state of the return air path switching component to appropriately adjust the effective heat recovery degree of the evaporator return air, thereby reasonably reducing the system's cooling capacity output and saving the working energy consumption of the freeze-thaw machine.

[0061] Optionally, the preset temperature difference can be set based on the ambient temperature. Specifically, the preset temperature difference can be set to 2°C to determine when the refrigeration system enters the temperature control phase. The preset temperature difference can also be adjusted according to the user's actual needs or set to any other reasonable value.

[0062] Optionally, the control device corrects the connectivity of the return gas path switching component, including: the control device determining the target opening degree of the third control valve based on the difference between the load temperature and the target temperature; and controlling the opening of the third control valve according to the target opening degree to adjust the amount of refrigerant passing through the third return gas branch. The target opening degree of the third control valve is negatively correlated with the difference between the load temperature and the target temperature.

[0063] Thus, as the difference between the load temperature and the target temperature decreases, this embodiment automatically increases the opening of the third control valve to increase the flow rate of refrigerant passing through the third return gas branch and participating in exhaust gas reheat. Therefore, this embodiment can utilize high-temperature exhaust gas to heat the evaporator return gas, thereby reasonably increasing the compressor's suction superheat to achieve a smooth reduction in the cooling capacity output of the refrigeration system, thus ensuring that the load temperature can quickly stabilize near the target temperature, achieving precise temperature control.

[0064] Based on the aforementioned refrigeration system for freeze-thaw machines, combined with Figure 6 As shown, this disclosure provides another control method for a refrigeration system of a freeze-thaw machine, including: S201, the control device acquires the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine.

[0065] S202, the control device controls the connection status of the return airflow path switching component according to the load temperature and ambient temperature.

[0066] S203, the control device acquires the operating parameters of the refrigerant circulation loop.

[0067] S204, the control device controls the working status of the component concentration adjustment branch according to the operating parameters of the refrigerant circulation loop.

[0068] The control method for the refrigeration system of a freeze-thaw machine provided in this disclosure acquires the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine, and controls the connection state of the return gas path switching component accordingly. This allows the evaporator return gas to selectively switch between different return gas paths based on the actual operating conditions. Specifically, when the freeze-thaw machine is in a high-temperature condition, the high-temperature return gas from the evaporator outlet flows directly back to the compressor, preventing reverse heat exchange with the refrigerant at the condenser outlet. This avoids the problem of reduced subcooling of the refrigerant at the condenser outlet and premature vaporization of low-boiling-point components in the non-azeotropic refrigerant mixture, thereby effectively maintaining the stable liquid phase state of the refrigerant at the inlet of the throttling device and ensuring the reliability of the throttling process and the operational stability of the refrigeration system. In a low-temperature condition, effective heat recovery is achieved by controlling the return gas flow through the regenerator, which fully utilizes the refrigeration advantages of the non-azeotropic refrigerant mixture in the low-temperature range. This allows the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range, meeting the actual needs of the freeze-thaw machine for precise temperature control over a wide temperature range. Furthermore, this embodiment of the present disclosure further obtains the operating parameters of the refrigerant circulation loop and controls the working state of the component concentration adjustment branch accordingly. This enables the gas-liquid separation of the refrigerant at the condenser outlet using a gas-liquid separator, and the storage or discharge of low-boiling-point gaseous refrigerant using an expansion tank. This allows for the reasonable adjustment of the component ratio of the non-azeotropic mixed refrigerant in the refrigerant circulation loop, so as to match the refrigerant composition with the current operating conditions. This is beneficial to further improve the low-temperature cooling capacity and high-temperature operating stability of the refrigeration system.

[0069] Optionally, the control device controls the operating state of the component concentration adjustment branch according to the operating parameters of the refrigerant circulation loop, including: the control device controls the opening and closing states of the fourth control valve and the fifth control valve according to the compressor's discharge pressure, so as to allow the expansion tank to store or discharge refrigerant; and / or, the control device controls the opening and closing states of the fourth control valve and the fifth control valve according to the evaporator's inlet temperature, so as to allow the expansion tank to store or discharge refrigerant.

[0070] Thus, this embodiment of the present disclosure can obtain the compressor's discharge pressure and / or the evaporator's inlet temperature. When the above operating parameters are determined to be abnormal, this embodiment of the present disclosure can appropriately adjust the working state of the component concentration adjustment branch, thereby enabling the gas-liquid separation of the refrigerant at the condenser outlet using a gas-liquid separator, and storing or discharging the low-boiling-point gaseous refrigerant in conjunction with an expansion tank. This allows for the reasonable adjustment of the component ratio of the non-azeotropic mixed refrigerant in the refrigerant circulation loop, so as to achieve a refrigerant composition that matches the current operating conditions, which is beneficial to further improve the low-temperature cooling capacity and high-temperature operating stability of the refrigeration system.

[0071] Optionally, the control device controls the opening and closing states of the fourth control valve and the fifth control valve according to the compressor's discharge pressure, so as to allow the expansion tank to store or discharge refrigerant, including: when the compressor's discharge pressure is greater than or equal to a preset discharge pressure, the control device opens the fourth control valve and closes the fifth control valve to allow the expansion tank to store refrigerant; or, when the compressor's discharge pressure is less than the preset discharge pressure, the control device closes the fourth control valve and closes the fifth control valve to allow the expansion tank to maintain refrigerant.

[0072] Thus, under conditions of high exhaust pressure, this embodiment of the present disclosure can open the fourth control valve and close the fifth control valve, allowing the low-boiling-point gaseous refrigerant separated by the gas-liquid separator to enter the expansion tank for storage. This reduces the concentration of low-boiling-point refrigerant in the refrigerant circulation loop, thereby suppressing the continuous increase in evaporation pressure and exhaust pressure, and preventing abnormal system operating pressure caused by an excessively high proportion of low-boiling-point components in the non-azeotropic refrigerant mixture. When the exhaust pressure is under normal operating conditions, this embodiment of the present disclosure closes both the fourth and fifth control valves, maintaining the refrigerant in the expansion tank in its current state. This ensures the stability of the refrigerant components in the refrigerant circulation loop and prevents fluctuations in system operating conditions caused by frequent adjustments to the refrigerant component concentration. Therefore, this embodiment of the present disclosure enables the non-azeotropic refrigerant mixture to maintain a reasonable component ratio under different operating conditions, allowing the refrigeration system to balance low-temperature cooling capacity and high-temperature operating stability over a wide temperature range.

[0073] Optionally, the preset exhaust pressure can be set in conjunction with the load temperature. Specifically, when the load temperature is greater than or equal to the ambient temperature, the preset exhaust pressure can be set to 1.85 MPa; when the load temperature is less than the ambient temperature, the preset exhaust pressure can be set to 1.65 MPa. The preset exhaust pressure can also be adjusted according to the user's actual needs, or set to any other reasonable value.

[0074] Optionally, the control device controls the opening and closing states of the fourth and fifth control valves based on the evaporator inlet temperature to allow the expansion tank to store or discharge refrigerant. This includes: when the evaporator inlet temperature is greater than or equal to the first inlet temperature, the control device closes the fourth control valve and opens the fifth control valve to allow the expansion tank to discharge refrigerant; or, when the evaporator inlet temperature is less than the first inlet temperature but greater than the second inlet temperature, the control device closes the fourth control valve and closes the fifth control valve to allow the expansion tank to maintain refrigerant; or, when the evaporator inlet temperature is less than or equal to the second inlet temperature, the control device opens the fourth control valve and closes the fifth control valve to allow the expansion tank to store refrigerant. Wherein, the first inlet temperature is greater than the second inlet temperature.

[0075] Thus, under high evaporator temperature conditions, this embodiment closes the fourth control valve and opens the fifth control valve, allowing the low-boiling-point refrigerant in the expansion tank to be discharged to the return gas branch. This increases the proportion of low-boiling-point refrigerant in the refrigerant circulation loop, fully utilizing the refrigeration advantages of low-boiling-point refrigerant in the low-temperature range and improving the system's refrigeration effect. When the evaporator temperature is normal, this embodiment closes both the fourth and fifth control valves, maintaining the refrigerant in the expansion tank in its current state to ensure stable refrigerant composition in the circulation loop and prevent frequent adjustments to refrigerant concentration from causing system fluctuations. When the evaporator temperature is low, this embodiment opens the fourth control valve and closes the fifth control valve, allowing the low-boiling-point gaseous refrigerant separated by the gas-liquid separator to enter the expansion tank for storage. This reduces the proportion of low-boiling-point refrigerant in the circulation loop, preventing refrigeration overflow and abnormal increases in system operating pressure. Therefore, this embodiment enables the non-azeotropic refrigerant mixture to maintain a reasonable component ratio under different operating conditions, allowing the refrigeration system to balance low-temperature refrigeration capacity and high-temperature operational stability over a wide temperature range.

[0076] Optionally, the first and second inlet temperatures can be set in conjunction with the load temperature. Specifically, when the load temperature is greater than or equal to the ambient temperature, the first inlet temperature can be set to the ambient temperature, and the second inlet temperature can be set to -20℃; when the load temperature is less than the ambient temperature but greater than or equal to the preset load temperature, the first inlet temperature can be set to -20℃, and the second inlet temperature can be set to -50℃; when the load temperature is less than the preset load temperature, the first inlet temperature can be set to -70℃, and the second inlet temperature can be set to -80℃. The first and second inlet temperatures can also be adjusted according to the user's actual needs or set to any other reasonable values.

[0077] Combination Figure 7As shown, this disclosure provides a control device 900 for a refrigeration system of a freeze-thaw machine, including a processor 901 and a memory 902. Optionally, the control device 900 may further include a communication interface 903 and a bus 904. The processor 901, communication interface 903, and memory 902 can communicate with each other via the bus 904. The communication interface 903 can be used for information transmission. The processor 901 can call logical instructions in the memory 902 to execute the control method for the refrigeration system of the freeze-thaw machine described in the above embodiment.

[0078] Furthermore, the logic instructions in the aforementioned memory 902 can be implemented as software functional units and, when sold or used as independent products, can be stored in a computer-readable storage medium.

[0079] The memory 902, as a computer-readable storage medium, can be used to store software programs and computer-executable programs, such as program instructions / modules corresponding to the methods in the embodiments of this disclosure. The processor 901 executes functional applications and data processing by running the program instructions / modules stored in the memory 902, thereby implementing the control method for the refrigeration system of the freeze-thaw machine in the above embodiments.

[0080] The memory 902 may include a program storage area and a data storage area. The program storage area may store the operating system and application programs required for at least one function; the data storage area may store data created based on the use of the terminal device. Furthermore, the memory 902 may include high-speed random access memory and may also include non-volatile memory.

[0081] This disclosure provides a computer-readable storage medium storing computer-executable instructions configured to execute the control method described above for a refrigeration system of a freeze-thaw machine.

[0082] The technical solutions of this disclosure can be embodied in the form of a software product. This computer software product is stored in a storage medium and includes one or more instructions to cause a computer device (which may be a personal computer, server, or network device, etc.) to execute all or part of the steps of the method described in this disclosure. The aforementioned storage medium can be a non-transitory storage medium, such as a USB flash drive, external hard drive, read-only memory (ROM), random access memory (RAM), magnetic disk, or optical disk, etc., and other media capable of storing program code.

[0083] The foregoing description and accompanying drawings fully illustrate embodiments of this disclosure to enable those skilled in the art to practice them. Other embodiments may include structural, logical, electrical, procedural, and other changes. The embodiments represent only possible variations. Individual components and functions are optional unless explicitly required, and the order of operation may vary. Parts and features of some embodiments may be included in or replace parts and features of other embodiments. Moreover, the terminology used in this application is for describing embodiments only and is not intended to limit the claims. As used in the description of embodiments and claims, the singular forms “a,” “an,” and “the” are intended to equally include the plural forms unless the context clearly indicates otherwise. Similarly, the term “and / or” as used in this application means including one or more of the associated listed items and all possible combinations thereof. Additionally, when used in this application, the term "comprise" and its variations "comprises" and / or "comprising" refer to the presence of stated features, integrals, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, integrals, steps, operations, elements, components, and / or groups thereof. Without further limitations, an element defined by the phrase "comprises a..." does not exclude the presence of other identical elements in the process, method, or apparatus that includes said element. In this document, each embodiment may focus on the differences from other embodiments, and similar or identical parts between embodiments can be referred to mutually. For methods, products, etc., disclosed in the embodiments, if they correspond to the method section disclosed in the embodiments, the relevant parts can be referred to the description of the method section.

[0084] Those skilled in the art will recognize that the units and algorithm steps of the various examples described in conjunction with the embodiments disclosed herein can be implemented in electronic hardware, or a combination of computer software and electronic hardware. Whether these functions are implemented in hardware or software depends on the specific application and design constraints of the technical solution. Those skilled in the art can use different methods to implement the described functions for each specific application, but such implementation should not be considered beyond the scope of the embodiments of this disclosure. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, devices, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here.

[0085] The methods and products disclosed in the embodiments herein (including but not limited to devices and equipment) can be implemented in other ways. For example, the device embodiments described above are merely illustrative. For instance, the division of units may be merely a logical functional division, and in actual implementation, there may be other division methods. For example, multiple units or components may be combined or integrated into another system, or some features may be ignored or not executed. In addition, the mutual coupling or direct coupling or communication connection shown or discussed may be through some interfaces, and the indirect coupling or communication connection of devices or units may be electrical, mechanical, or other forms. The units described as separate components may or may not be physically separate. The components shown as units may or may not be physical units, that is, they may be located in one place or distributed across multiple network units. Some or all of the units can be selected to implement this embodiment according to actual needs. In addition, the functional units in the embodiments of this disclosure may be integrated into one processing unit, or each unit may exist physically separately, or two or more units may be integrated into one unit.

[0086] The flowcharts and block diagrams in the accompanying drawings illustrate the architecture, functionality, and operation of possible implementations of systems, methods, and computer program products according to embodiments of this disclosure. In this regard, each block in a flowchart or block diagram may represent a module, segment, or portion of code containing one or more executable instructions for implementing a specified logical function. In some alternative implementations, the functions marked in the blocks may occur in a different order than that shown in the drawings. For example, two consecutive blocks may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. In the descriptions corresponding to the flowcharts and block diagrams in the accompanying drawings, the operations or steps corresponding to different blocks may also occur in a different order than disclosed in the description, and sometimes there is no specific order between different operations or steps. For example, two consecutive operations or steps may actually be executed substantially in parallel, and they may sometimes be executed in reverse order, depending on the functions involved. Each block in a block diagram and / or flowchart, and combinations of blocks in a block diagram and / or flowchart, can be implemented using a dedicated hardware-based system that performs the specified function or action, or using a combination of dedicated hardware and computer instructions.

Claims

1. A refrigeration system for a freeze-thaw machine, characterized in that, include: The refrigerant circulation loop includes a compressor, condenser, first regenerator, throttling device, and evaporator connected in sequence through refrigerant pipelines. The refrigerant circulation loop is filled with a variety of refrigerants with different boiling points. The return gas path switching component is located between the outlet of the evaporator and the suction port of the compressor and is configured to selectively connect the first return gas branch or the second return gas branch. The first return gas branch connects the outlet of the evaporator and the suction port of the compressor, and does not pass through the first regenerator; the second return gas branch connects the outlet of the evaporator and the suction port of the compressor, and passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator.

2. The refrigeration system according to claim 1, characterized in that, The return flow path switching component includes: The first control valve is located in the first return gas branch; The second control valve is located in the second return gas branch.

3. The refrigeration system according to claim 1, characterized in that, Also includes: The second regenerator has its first flow path located between the compressor's exhaust port and the condenser's inlet; The third return gas branch connects the outlet of the evaporator with the suction port of the compressor, and passes through the second flow path of the second regenerator and exchanges heat with the first flow path of the second regenerator.

4. The refrigeration system according to claim 3, characterized in that, The return flow path switching component also includes: The third control valve is located in the third return gas branch.

5. The refrigeration system according to claim 1, characterized in that, Also includes: A gas-liquid separator is installed between the outlet of the condenser and the inlet of the first flow path of the first regenerator; The component concentration regulating branch is located between the gas phase outlet of the gas-liquid separator and the outlet of the second flow path of the first regenerator, and an expansion tank is installed on the component concentration regulating branch.

6. The refrigeration system according to claim 5, characterized in that, The component concentration regulation branch also includes: The fourth control valve is located between the gas phase outlet of the gas-liquid separator and the inlet of the expansion tank; The fifth control valve is located between the outlet of the expansion tank and the outlet of the second flow path of the first regenerator.

7. A control method for a refrigeration system of a freeze-thaw machine, characterized in that, Applied to the refrigeration system as described in any one of claims 1 to 6; the control method includes: Obtain the load temperature inside the freeze-thaw machine and the ambient temperature outside the freeze-thaw machine; The connection status of the return airflow path switching component is controlled based on the load temperature and ambient temperature.

8. The control method according to claim 7, characterized in that, Based on the load temperature and ambient temperature, control the connection status of the return airflow path switching component, including: When the load temperature is greater than or equal to the ambient temperature, the return gas flow path switching component is connected to the first return gas branch so that the refrigerant at the evaporator outlet does not flow back to the compressor suction port through the first regenerator; or, When the load temperature is lower than the ambient temperature, the control return gas path switching component connects to the second return gas branch so that the refrigerant at the evaporator outlet first passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator before flowing back to the compressor's suction port.

9. The control method according to claim 8, characterized in that, The refrigeration system further includes: a second regenerator, the first flow path of which is located between the compressor's discharge port and the condenser's inlet; a third return gas branch, connecting the evaporator's outlet and the compressor's suction port, and passing through the second flow path of the second regenerator and exchanging heat with the first flow path of the second regenerator; when the load temperature is lower than the ambient temperature, the control method further includes: When the load temperature is lower than the preset load temperature, the control return gas path switching component connects the second return gas branch and the third return gas branch at the same time, so that part of the refrigerant at the evaporator outlet passes through the second flow path of the first regenerator and exchanges heat with the first flow path of the first regenerator, and the other part passes through the second flow path of the second regenerator and exchanges heat with the first flow path of the second regenerator, and finally flows back to the compressor suction port. The preset load temperature is lower than the ambient temperature.

10. The control method according to any one of claims 7 to 9, characterized in that, The refrigeration system also includes: a gas-liquid separator, located between the outlet of the condenser and the inlet of the first flow path of the first regenerator; a component concentration regulating branch, located between the gas phase outlet of the gas-liquid separator and the outlet of the second flow path of the first regenerator, wherein an expansion tank is installed on the component concentration regulating branch; and after controlling the connection state of the return flow path switching component according to the load temperature and ambient temperature, it also includes: Obtain the operating parameters of the refrigerant circulation loop; The operating status of the component concentration regulating branch is controlled based on the operating parameters of the refrigerant circulation loop.

11. The control method according to claim 10, characterized in that, The component concentration regulation branch also includes: a fourth control valve, located between the gas phase outlet of the gas-liquid separator and the inlet of the expansion tank; and a fifth control valve, located between the outlet of the expansion tank and the outlet of the second flow path of the first regenerator. Based on the operating parameters of the refrigerant circulation loop, the operating state of the component concentration regulation branch is controlled, including: Based on the compressor's discharge pressure, control the opening and closing states of the fourth and fifth control valves to allow the expansion tank to store or discharge refrigerant; and / or, Based on the evaporator inlet temperature, the opening and closing states of the fourth and fifth control valves are controlled to allow the expansion tank to store or discharge refrigerant.

12. A control device for a refrigeration system of a freeze-thaw machine, comprising a processor and a memory storing program instructions, characterized in that, The processor is configured to, when executing the program instructions, perform the control method for a refrigeration system for a freeze-thaw machine as described in any one of claims 7 to 11.

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