Refrigeration system, medical low-temperature storage box and anti-blocking method of refrigeration system

Abstract

The present disclosure relates to a refrigeration system, a medical low-temperature storage box, and an anti-blocking method for the refrigeration system. The refrigeration system includes a first compressor, a first heat exchanger, a throttling assembly, and a second heat exchanger. Along the refrigerant flow direction, the first compressor, the first heat exchanger, the throttling assembly, the second heat exchanger, and the first compressor are connected in sequence. The throttling assembly includes a first capillary tube and a second capillary tube connected in parallel. The length of the first capillary tube is greater than that of the second capillary tube. The first capillary tube and the second capillary tube are configured to be in a working state alternatively. Under normal conditions, the first capillary tube is in a working state. In the case of system blockage, the second capillary tube is in a working state, which can enable the lubricating oil to flow back to the first compressor along with the refrigerant, realizing the reuse of the lubricating oil accumulated in the second heat exchanger in the cycle, avoiding the blockage of the refrigeration system, enhancing the heat exchange effect of the second heat exchanger, and the lubricating oil flowing back to the first compressor, improving the service life of the first compressor.

Description

Technical Field

[0001] The present disclosure relates to the field of refrigeration technology, and particularly to a refrigeration system, a medical low-temperature storage box, and a method for preventing blockage of the refrigeration system. Background Art

[0002] For low-temperature refrigeration products, especially the low-temperature stage refrigeration system using a multi-stage refrigeration cycle, the lubricating oil existing in the system is difficult to flow due to the increase in viscosity caused by the decrease in temperature. Therefore, an oil separator is provided at the exhaust outlet position of the compressor to reduce the oil content in the refrigerant. However, the oil separator cannot achieve a complete oil separation effect, and there will always be a small amount of lubricating oil entering the system and participating in the refrigeration cycle. Under long-term operation, part of the lubricating oil will accumulate in the pipeline, especially on the evaporator side. The long-term accumulation will affect the heat exchange effect of the evaporator, reduce the refrigeration capacity of the system, and thus cause the temperature in the space to be heat-exchanged not to reach the target temperature. Moreover, the reduction in the lubricating oil circulation volume will also cause the lubrication effect of the compressor to deteriorate and reduce the service life of the compressor. Summary of the Invention

[0003] Some embodiments of the present disclosure provide a refrigeration system, a medical low-temperature storage box, and a method for preventing blockage of the refrigeration system to alleviate the problem of blockage of the refrigeration system.

[0004] In one aspect of the present disclosure, a refrigeration system is provided, including a first compressor, a first heat exchanger, a throttling assembly, and a second heat exchanger; along the refrigerant flow direction, the first compressor, the first heat exchanger, the throttling assembly, the second heat exchanger, and the first compressor are connected in sequence, wherein the throttling assembly includes a first capillary tube and a second capillary tube connected in parallel, the length of the first capillary tube is greater than that of the second capillary tube, and the first capillary tube and the second capillary tube are configured to be alternatively in a working state.

[0005] In some embodiments, the first capillary tube is configured to make the temperature of the refrigerant passing through it lower than the pour point of the lubricating oil to obtain a low-temperature storage environment, and the second capillary tube is configured to make the temperature of the refrigerant passing through it higher than the pour point of the lubricating oil.

[0006] In some embodiments, the refrigeration system further includes:

[0007] a first control valve, disposed on the pipeline where the first capillary tube is located, and configured to control the first capillary tube to be in a working state or a non-working state; and

[0008] a second control valve, disposed on the pipeline where the second capillary tube is located, and configured to control the second capillary tube to be in a working state or a non-working state.

[0009] In some embodiments, the refrigeration system further includes a controller, which is electrically connected to the first control valve and the second control valve, and is configured to control the opening of the first control valve or the second control valve so that the first capillary tube or the second capillary tube is in an operating state.

[0010] In some embodiments, the controller is configured to control the first compressor to operate at a target frequency and control the first control valve to open during the initial startup and operation stage of the first compressor.

[0011] In some embodiments, the refrigeration system further includes a temperature detector electrically connected to the controller. The temperature detector is configured to detect the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger, and the controller is configured to receive the temperature signal detected by the temperature detector;

[0012] The controller is further configured to control the first control valve to close, the second control valve to open, and the first compressor to operate at the maximum frequency when the cumulative startup and operation time of the first compressor < the first preset time t1 and the temperature Tx in the space is still > the set temperature value Ts within the set time.

[0013] In some embodiments, the refrigeration system further includes a temperature detector electrically connected to the controller. The temperature detector is configured to detect the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger, and the controller is configured to receive the temperature signal detected by the temperature detector;

[0014] The controller is further configured to control the first compressor to operate at the maximum frequency when the cumulative startup and operation time of the first compressor ≥ the first preset time t1.

[0015] In some embodiments, the controller is further configured to control the first control valve to close, the second control valve to open, and the first compressor to maintain operation at the maximum frequency when the operation time of the first compressor at the maximum frequency ≥ the second preset time t2, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger < the set temperature value Ts - ΔT1.

[0016] In some embodiments, the controller is configured to control the first control valve to open, the second control valve to close, and the first compressor to operate at the target frequency when the operation time of the first compressor at the maximum frequency ≥ the third preset time t3, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger > the set temperature value Ts + ΔT2.

[0017] In some embodiments, the refrigeration system further includes a second compressor, a third heat exchanger, and a throttling member. Along the flow direction of the refrigerant, the second compressor, the third heat exchanger, the throttling member, the first heat exchanger, and the second compressor are connected in sequence.

[0018] In one aspect of the present disclosure, there is provided a medical low-temperature storage box, including:

[0019] A box body, inside which a storage space for accommodating items is formed; and

[0020] The above-mentioned refrigeration system, wherein the second heat exchanger is configured to cool the storage space.

[0021] In some embodiments, the medical low-temperature storage box further includes a second compressor, a third heat exchanger, and a throttling member provided outside the box body. Along the flow direction of the refrigerant, the second compressor, the third heat exchanger, the throttling member, the first heat exchanger, and the second compressor are connected in sequence.

[0022] In one aspect of the present disclosure, there is provided a method for preventing blockage of a refrigeration system, including the following steps:

[0023] The first compressor is turned on, entering a working mode in which the first capillary tube is in a working state and the second capillary tube is in a non-working state, and the first compressor operates at a target frequency.

[0024] When the refrigeration system is blocked and the second heat exchanger is seriously oil-accumulated, switch to a working mode in which the second capillary tube is in a working state, the first capillary tube is in a non-working state, and the first compressor operates at the maximum frequency.

[0025] When the blockage of the refrigeration system is relieved, that is, when the lubricating oil accumulated in the second heat exchanger returns to the first compressor, switch to a working mode in which the first capillary tube is in a working state, the second capillary tube is in a non-working state, and the first compressor operates at a target frequency.

[0026] In some embodiments, the method for preventing blockage of the refrigeration system further includes a method for judging that the refrigeration system is blocked, which includes the following steps:

[0027] After entering the working mode in which the first capillary tube is in a working state, the second capillary tube is in a non-working state, and the first compressor operates at a target frequency:

[0028] When the cumulative start-up operation time of the first compressor < the first preset time t1; and the temperature Tx in the space where the second heat exchanger needs to exchange heat is still > the set temperature value Ts within the set time, it is judged that the refrigeration system is blocked, the second heat exchanger is seriously oil-accumulated, and the normal refrigeration and heat exchange have been affected.

[0029] In some embodiments, the anti-blocking method of the refrigeration system further includes a method for judging the blockage of the refrigeration system, which includes the following steps:

[0030] After entering the working mode in which the first capillary tube is in the working state, the second capillary tube is in the non-working state, and the first compressor operates at the target frequency:

[0031] When the cumulative start-up operation time of the first compressor ≥ the first preset time t1, considering that a part of the lubricating oil has been accumulated in the second heat exchanger at this time, it is judged that the refrigeration system is blocked.

[0032] In some embodiments, when the cumulative start-up operation time of the first compressor 11 ≥ the first preset time t1 and it is judged that the refrigeration system is blocked, first control the first compressor to operate at the maximum frequency for precooling; when the operation time of the first compressor at the maximum frequency ≥ the second preset time t2, or the temperature Tx in the space where the second heat exchanger needs to exchange heat < the set temperature value Ts - ΔT1, switch to the working mode in which the second capillary tube is in the working state, the first capillary tube is in the non-working state, and the first compressor operates at the maximum frequency.

[0033] In some embodiments, the anti-blocking method of the refrigeration system further includes a method for judging the release of the blockage of the refrigeration system, which includes the following steps:

[0034] After entering the working mode in which the second capillary tube is in the working state, the first capillary tube is in the non-working state, and the first compressor operates at the maximum frequency;

[0035] When the operation time of the first compressor at the maximum frequency ≥ the third preset time t3, or the temperature Tx in the space where the second heat exchanger needs to exchange heat > the set temperature value Ts + ΔT2, it is judged that the blockage of the refrigeration system is released.

[0036] Based on the above technical solutions, the present disclosure has at least the following beneficial effects:

[0037] In some embodiments, the throttling component in the refrigeration system includes a first capillary tube and a second capillary tube connected in parallel; under normal circumstances, the first capillary tube is in a working state, and the second capillary tube is in a non-working state. The length of the first capillary tube is greater than that of the second capillary tube. Therefore, the temperature after throttling and pressure reduction by the first capillary tube is much lower than that of the second capillary tube, which is used to obtain an ultra-low temperature storage environment. When the first capillary tube is in a non-working state and the length of the second capillary tube is less than that of the first capillary tube, the temperature of the refrigerant after throttling and cooling by the second capillary tube is higher than that after throttling and cooling by the first capillary tube. The refrigerant at a higher temperature enters the second heat exchanger, which can heat the lubricating oil accumulated in the second heat exchanger, causing the lubricating oil to flow back to the first compressor along with the refrigerant, realizing the recycling of the lubricating oil accumulated in the second heat exchanger and avoiding blockage of the refrigeration system; enhancing the heat exchange effect of the second heat exchanger, and the lubricating oil flowing back to the first compressor improves the service life of the first compressor. Description of the Drawings

[0038] The drawings described herein are used to provide a further understanding of the present disclosure, form a part of this application, and the illustrative embodiments and descriptions thereof of the present disclosure are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure. In the drawings:

[0039] Figure 1 is a schematic diagram of a refrigeration system provided according to some embodiments of the present disclosure;

[0040] Figure 2 is a schematic flowchart of a method for preventing blockage of a refrigeration system provided according to some embodiments of the present disclosure.

[0041] The reference numerals in the drawings are described as follows:

[0042] 11 - First compressor; 12 - Second compressor;

[0043] 21 - First heat exchanger; 22 - Second heat exchanger; 23 - Third heat exchanger;

[0044] 3 - Throttling component; 31 - First capillary tube; 32 - Second capillary tube;

[0045] 4 - Controller;

[0046] 51 - First control valve; 52 - Second control valve;

[0047] 6 - Temperature detection component;

[0048] 7 - Throttling element;

[0049] 81 - First drying filter; 82 - Second drying filter;

[0050] 9 - Oil separator.

[0051] It should be understood that the dimensions of the various parts shown in the drawings are not drawn to actual scale. In addition, the same or similar reference numerals denote the same or similar components. Detailed Description of the Invention

[0052] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and in no way limits the present disclosure or its application or use. The present disclosure may be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that: unless otherwise specifically stated, the relative arrangements of components and steps, the compositions of materials, the numerical expressions and values set forth in these embodiments should be construed as merely exemplary and not as limitations.

[0053] The terms "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are merely used to distinguish different parts. Terms such as "comprising" or "including" mean that the elements preceding the term cover the elements recited after the term and do not exclude the possibility of also covering other elements. Terms such as "upper", "lower", "left", "right" are only used to indicate relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0054] In the present disclosure, when it is described that a specific device is located between a first device and a second device, there may or may not be an intermediate device between the specific device and the first device or the second device. When it is described that a specific device is connected to other devices, the specific device may be directly connected to the other devices without an intermediate device, or may not be directly connected to the other devices and have an intermediate device.

[0055] All terms used in the present disclosure (including technical terms or scientific terms) have the same meaning as understood by those of ordinary skill in the art to which the present disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in a general dictionary such as should be construed as having a meaning consistent with their meaning in the context of the relevant art and should not be interpreted in an idealized or overly formal sense unless specifically defined as such herein.

[0056] Techniques, methods and devices known to those of ordinary skill in the relevant art may not be discussed in detail, but where appropriate, the techniques, methods and devices should be regarded as part of the specification.

[0057] Figure 1 is a schematic structural diagram of some embodiments of the refrigeration system according to the present disclosure. Refer to Figure 1, in some embodiments, the refrigeration system includes a first compressor 11, a first heat exchanger 21, a throttling assembly 3, and a second heat exchanger 22; along the refrigerant flow direction, the first compressor 11, the first heat exchanger 21, the throttling assembly 3, the second heat exchanger 22, and the first compressor 11 are connected in sequence. The throttling assembly 3 includes a first capillary tube 31 and a second capillary tube 32 connected in parallel. The length of the first capillary tube 31 is greater than that of the second capillary tube 32. The first capillary tube 31 and the second capillary tube 32 are configured to be in a working state alternatively.

[0058] The refrigerant mentioned in the embodiments of the present disclosure is the refrigerant used in the refrigeration system, and the lubricating oil is the lubricating oil used to lubricate the first compressor 11 in the refrigeration system. The lubricating oil for lubricating the first compressor 11 is discharged from the outlet of the first compressor 11 along with the refrigerant. Since the temperature of the refrigerant decreases, the temperature of the lubricating oil will decrease, the viscosity will increase, and it is difficult to flow. During the long-term operation of the refrigeration system, some lubricating oil will accumulate in the evaporator, that is, the second heat exchanger 22 in the embodiments of the present disclosure. The lubricating oil accumulated for a long time will cause system blockage, affect the heat exchange effect of the second heat exchanger 22, reduce the refrigeration capacity of the system, and thus cause the temperature in the space where the second heat exchanger 22 needs to perform heat exchange to fail to reach the target temperature; moreover, the reduction in the lubricating oil circulation volume will also cause the lubrication effect of the first compressor 11 to deteriorate and reduce the service life of the first compressor 11.

[0059] Based on this, some embodiments of the present disclosure provide a refrigeration system, which includes a first capillary tube 31 and a second capillary tube 32 connected in parallel. The length of the first capillary tube 31 is greater than that of the second capillary tube 32. The first capillary tube 31 and the second capillary tube 32 can be switched for use to alleviate the problem of lubricating oil accumulation in the refrigeration system, avoid system blockage, improve the heat exchange effect of the second heat exchanger 22, and improve the service life of the first compressor 11.

[0060] Specifically: Under normal conditions, the first capillary 31 is in a working state, and the second capillary 32 is in a non-working state. The length of the first capillary 31 is greater than that of the second capillary 32. Therefore, the temperature after throttling and pressure reduction by the first capillary 31 is much lower than that of the second capillary 32, which is used to obtain an ultra-low temperature storage environment. When the second heat exchanger 22 is severely oil-accumulated and the system is blocked, the second capillary 32 is in a working state, and the first capillary 31 is in a non-working state. The length of the second capillary 32 is less than that of the first capillary 31. The temperature of the refrigerant after throttling and cooling by the second capillary 32 is higher than that of the refrigerant after throttling and cooling by the first capillary 31. The refrigerant at a higher temperature enters the second heat exchanger 22, which can heat the lubricating oil accumulated in the second heat exchanger 22, so that the lubricating oil flows back to the first compressor 11 along with the refrigerant, enabling the lubricating oil accumulated in the second heat exchanger 22 to participate in the cycle again, avoiding the blockage of the refrigeration system; enhancing the heat exchange effect of the second heat exchanger 22 and solving the problem of poor heat exchange effect of the second heat exchanger 22; and the lubricating oil flows back to the first compressor 11, improving the service life of the first compressor 11. Moreover, compared with the traditional refrigeration system, the refrigeration system provided by the embodiments of the present disclosure only adds one capillary, having the advantages of simple structure and low cost.

[0061] The normal conditions described in the embodiments of the present disclosure include the initial startup stage of the first compressor 11 and after the blockage of the refrigeration system is relieved.

[0062] Under normal conditions, the first capillary 31 is in a working state, and the second capillary 32 is in a non-working state. When the system is blocked, the second capillary 32 is in a working state, and the first capillary 31 is in a non-working state. The working states of the first capillary 31 and the second capillary 32 can be switched according to specific conditions. Therefore, it is possible to avoid excessive accumulation of lubricating oil in the second heat exchanger 22 in the refrigeration system from causing blockage of the refrigeration system on the premise of minimizing the impact on the temperature in the space where the second heat exchanger 22 needs to perform heat exchange, and reducing the impact of oil accumulation on the heat exchange effect and refrigerating capacity of the second heat exchanger 22.

[0063] In some embodiments, the inner diameter of the first capillary 31 is smaller than that of the second capillary 32.

[0064] In some embodiments, the first capillary 31 is configured such that the temperature of the refrigerant passing through it is much lower than the pour point of the lubricating oil to obtain an ultra-low temperature. The second capillary 32 is configured such that the temperature of the refrigerant passing through it is higher than the pour point of the lubricating oil.

[0065] After the refrigerant passes through the first capillary tube 31 for throttling and temperature reduction, the temperature is lower than the pour point of the lubricating oil, and the lubricating oil is likely to accumulate in the second heat exchanger 22. The length of the second capillary tube 32 is shorter than that of the first capillary tube 31. After the refrigerant passes through the second capillary tube 32 for throttling and temperature reduction, the temperature is higher than the pour point of the lubricating oil. The refrigerant with a higher temperature passes through the second heat exchanger 22, which can increase the temperature of the lubricating oil accumulated in the second heat exchanger 22, enabling the lubricating oil accumulated in the second heat exchanger 22 to flow back to the first compressor 11 along with the refrigerant, realizing the reuse of the lubricating oil accumulated in the second heat exchanger 22 in the cycle, avoiding the blockage of the refrigeration system, enhancing the heat exchange effect of the second heat exchanger 22, and when the lubricating oil flows back to the first compressor 11, it can extend the service life of the first compressor 11.

[0066] In some embodiments, the temperature of the refrigerant after throttling and temperature reduction through the first capillary tube 31 is -86°C. The temperature of the refrigerant after throttling and temperature reduction through the second capillary tube 32 is -40°C.

[0067] In some embodiments, the refrigeration system further includes a first control valve 51. The first control valve 51 is arranged on the pipeline where the first capillary tube 31 is located, and the first control valve 51 is configured to control the first capillary tube 31 to be in a working state or a non-working state.

[0068] When the first control valve 51 is opened, the first capillary tube 31 is in a working state. When the first control valve 51 is closed, the first capillary tube 31 is in a non-working state.

[0069] In some embodiments, the refrigeration system further includes a second control valve 52. The second control valve 52 is arranged on the pipeline where the second capillary tube 32 is located and is configured to control the second capillary tube 32 to be in a working state or a non-working state.

[0070] When the second control valve 52 is opened, the second capillary tube 32 is in a working state. When the second control valve 52 is closed, the second capillary tube 32 is in a non-working state.

[0071] In some embodiments, the refrigeration system further includes a controller 4. The controller 4 is electrically connected to the first control valve 51 and the second control valve 52. The controller 4 is configured to control the first control valve 51 to open so that the first capillary tube 31 is in a working state, and the controller 4 is further configured to control the first control valve 51 to close so that the first capillary tube 31 is in a non-working state.

[0072] The controller 4 is further configured to control the second control valve 52 to open so that the second capillary tube 32 is in a working state, and the controller 4 is further configured to control the second control valve 52 to close so that the second capillary tube 32 is in a non-working state.

[0073] In some embodiments, the controller 4 is further configured to control the first compressor 11 to operate at a target frequency during the initial startup and operation stage of the first compressor 11, and control the first control valve 51 to open and the second control valve 52 to close.

[0074] The first compressor 11 is a variable-frequency compressor. The target frequency of the first compressor 11 can be determined according to parameters such as the set target temperature.

[0075] In some embodiments, the refrigeration system further includes a temperature detector 6 electrically connected to the controller 4. The temperature detector 6 is configured to detect the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22, and the controller 4 is configured to receive the temperature signal detected by the temperature detector 6.

[0076] The controller 4 is further configured to control the first control valve 51 to close and the second control valve 52 to open, and the first compressor 11 to operate at the maximum frequency when the cumulative startup and operation time of the first compressor 11 < the first preset time t1 and the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22 is still > the set temperature value Ts within the set time.

[0077] In some embodiments, the refrigeration system further includes a temperature detector 6 electrically connected to the controller 4. The temperature detector 6 is configured to detect the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22, and the controller 4 is configured to receive the temperature signal detected by the temperature detector 6.

[0078] The controller 4 is further configured to control the first compressor 11 to operate at the maximum frequency when the cumulative startup and operation time of the first compressor 11 ≥ the first preset time t1.

[0079] In some embodiments, the controller 4 is configured to control the first control valve 51 to close and the second control valve 52 to open, and the first compressor 11 to operate at the maximum frequency when the operation time of the first compressor 11 at the maximum frequency ≥ the second preset time t2, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22 < the set temperature value Ts - ΔT1.

[0080] In some embodiments, △T1 = 2K to 4K.

[0081] In some embodiments, the controller 4 is configured to control the first control valve 51 to open and the second control valve 52 to close, and the first compressor 11 to operate at the target frequency when the operation time of the first compressor 11 at the maximum frequency ≥ the third preset time t3, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22 > the set temperature value Ts + ΔT2.

[0082] In some embodiments, △T2 = 1K to 2K.

[0083] In some embodiments, the refrigeration system further includes a second compressor 12, a third heat exchanger 23, and a throttling member 7. Along the flow direction of the refrigerant, the second compressor 12, the third heat exchanger 23, the throttling member 7, the first heat exchanger 21, and the second compressor 12 are connected in sequence.

[0084] The refrigerant in both the first compressor 11 and the second compressor 12 passes through the first heat exchanger 21. When the refrigerant in the second compressor 12 passes through the first heat exchanger 21, it absorbs heat and evaporates. When the refrigerant in the first compressor 11 passes through the first heat exchanger 21, it releases heat and condenses. The refrigerant provided by the second compressor 12 cools the refrigerant provided by the first compressor 11 in the first heat exchanger 21. Compared with cooling in a normal environment, the temperature of the refrigerant provided by the first compressor 11 can be reduced to an extremely low level, so that after the refrigerant provided by the first compressor 11 is cooled in the first heat exchanger 21, it is further cooled by the throttling assembly 3 and exchanges heat with the space to be cooled in the second heat exchanger 22, enabling the space to be cooled to an extremely low temperature environment and meeting the usage requirements.

[0085] The throttling member 7 in the refrigeration cycle pipeline where the second compressor 12 is located can also be a capillary tube.

[0086] The probability of blockage in the refrigeration cycle pipeline where the second compressor 12 is located is small. This is because in the refrigeration cycle pipeline where the second compressor 12 is located, the temperature of the refrigerant after throttling by the throttling member 7 is about -40°C, while the pour point temperature of the lubricating oil is about -50°C. Therefore, the probability of blockage in the refrigeration cycle pipeline where the second compressor 12 is located is extremely small.

[0087] For the refrigeration cycle pipeline where the first compressor 11 is located, since it shares the first heat exchanger 21 with the refrigeration cycle pipeline where the second compressor 11 is located, the temperature of the refrigerant flowing through the first heat exchanger 21 in the refrigeration cycle pipeline where the first compressor 11 is located can be reduced to an extremely low level. The temperature of the refrigerant passing through the throttling assembly 3 can reach -80°C, which is much lower than the pour point of the lubricating oil. Therefore, the lubricating oil is likely to accumulate in the second heat exchanger 22, causing blockage of the refrigeration system. The parallel first capillary tube 31 and second capillary tube 32 provided in the embodiments of the present disclosure can be switched to alleviate the problem of blockage of the refrigeration system.

[0088] In some embodiments, the refrigeration system further includes an oil separator 9. The oil separator 9 is provided on the pipeline between the first compressor 11 and the first heat exchanger 21. The oil separator 9 is connected to the first compressor 11 through an oil return pipeline. The oil separator 9 is used to separate the lubricating oil in the refrigerant and send the separated lubricating oil back to the first compressor 11 through the oil return pipeline, reducing the oil content in the refrigerant.

[0089] In some embodiments, the refrigeration system further includes a first drying filter 81, which is disposed on the pipeline between the first heat exchanger 21 and the throttling assembly 3. The first drying filter 81 is used to absorb moisture in the refrigerant.

[0090] In some embodiments, the refrigeration system further includes a second drying filter 82, which is disposed on the pipeline between the third heat exchanger 23 and the throttling member 7. The second drying filter 82 is used to absorb moisture in the refrigerant.

[0091] Some embodiments also provide a method for preventing blockage of a refrigeration system, which includes the following steps:

[0092] The first compressor 11 is turned on, entering a working mode in which the first capillary tube 31 is in a working state, the second capillary tube 32 is in a non-working state, and the first compressor 11 operates at a target frequency.

[0093] In the case of blockage in the refrigeration system, switch to a working mode in which the second capillary tube 32 is in a working state, the first capillary tube 31 is in a non-working state, and the first compressor 11 operates at the maximum frequency.

[0094] In the case of the blockage in the refrigeration system being relieved, switch to a working mode in which the first capillary tube 31 is in a working state, the second capillary tube 32 is in a non-working state, and the first compressor 11 operates at a target frequency.

[0095] Under normal circumstances, the system operates stably, and according to the set target temperature, the first compressor 11 operates at a target frequency.

[0096] The stage when the first compressor 11 is just turned on and the stage after the blockage in the refrigeration system is relieved are normal situations.

[0097] In some embodiments, the method for preventing blockage of the refrigeration system further includes a method for determining blockage in the refrigeration system, which includes the following steps:

[0098] After entering the working mode in which the first capillary tube 31 is in a working state, the second capillary tube 32 is in a non-working state, and the first compressor 11 operates at a target frequency:

[0099] When the cumulative startup operation time of the first compressor 11 < the first preset time t1; and the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22 is still > the set temperature value Ts within the set time, it is determined that the refrigeration system is blocked.

[0100] In the operating mode where the first compressor 11 operates at the target frequency, if the temperature Tx in the space where the second heat exchanger 22 is to exchange heat drops to the set temperature value Ts, the first compressor 11 will shut down. When the temperature Tx in the space where the second heat exchanger 22 is to exchange heat is higher than the set temperature value Ts, the first compressor 11 will start up. Therefore, in the operating mode where the first compressor 11 operates at the target frequency, there may be multiple start-ups and shutdowns. Therefore, after entering the operating mode where the first capillary 31 is in the working state, the second capillary 32 is in the non-working state, and the first compressor 11 operates at the target frequency, the relationship between the cumulative start-up running time of the first compressor 11 and the first preset time t1 is statistically analyzed. Among them, the set temperature value Ts is extremely low, possibly -80°C to -90°C.

[0101] In some embodiments, the anti-blocking method of the refrigeration system further includes a method for judging whether the refrigeration system is blocked, which includes the following steps:

[0102] After entering the operating mode where the first capillary 31 is in the working state, the second capillary 32 is in the non-working state, and the first compressor 11 operates at the target frequency:

[0103] When the cumulative start-up running time of the first compressor 11 ≥ the first preset time t1, it is judged that the refrigeration system is blocked.

[0104] Before switching to the operating mode where the second capillary 32 is in the working state, the first capillary 31 is in the non-working state, and the first compressor 11 operates at the maximum frequency, first control the first compressor 11 to operate at the maximum frequency for precooling; when the running time of the first compressor 11 at the maximum frequency ≥ the second preset time t2, or when the temperature Tx in the space where the second heat exchanger 22 is to exchange heat < the set temperature value Ts - ΔT1, switch to the operating mode where the second capillary 32 is in the working state, the first capillary 31 is in the non-working state, and the first compressor 11 operates at the maximum frequency.

[0105] Among them, the operating mode where the first capillary 31 is in the working state, the second capillary 32 is in the non-working state, and the first compressor 11 operates at the target frequency is the refrigeration mode.

[0106] The operating mode where the first capillary 31 is in the working state, the second capillary 32 is in the non-working state, and the first compressor 11 operates at the maximum frequency is the precooling mode.

[0107] The operating mode where the second capillary 32 is in the working state, the first capillary 31 is in the non-working state, and the first compressor 11 operates at the maximum frequency is the oil return mode.

[0108] Under normal circumstances, the system operates stably. According to the set target temperature, the first compressor 11 operates at the target frequency, and the working mode is the cooling mode. When the cumulative startup operation time of the first compressor 11 is ≥ the first preset time t1, the first compressor 11 is controlled to operate at the maximum frequency and enter the pre-cooling mode. The pre-cooling mode means that the compressor operating frequency is turned to the maximum and the cooling temperature reaches the minimum. The purpose of this is to avoid a significant rise in the temperature Tx in the space where the second heat exchanger 22 is to perform heat exchange after entering the oil return mode, causing the average temperature to deviate significantly from the set temperature value Ts.

[0109] In some embodiments, the method for preventing blockage of a refrigeration system further includes a method for determining whether blockage of the refrigeration system is released, which includes the following steps:

[0110] After entering the working mode in which the second capillary tube 32 is in working state, the first capillary tube 31 is in non-working state, and the first compressor 11 operates at the maximum frequency;

[0111] When the time when the first compressor 11 runs at the maximum frequency is ≥ the third preset time t3, or the temperature Tx in the space where the second heat exchanger 22 is to perform heat exchange is greater than the set temperature value Ts+ΔT2, it is determined that the refrigeration system is unblocked.

[0112] In some embodiments, in the anti-blocking method of the refrigeration system, the conditions for switching to the oil return mode include at least the following two conditions:

[0113] 1) The first compressor 11 is turned on, and the refrigeration system operates in the refrigeration mode. When the accumulated startup operation time of the first compressor 11 is greater than or equal to the first preset time t1, the first compressor 1 operates at the maximum frequency and enters the pre-cooling mode. When the time when the first compressor 1 operates at the maximum frequency is greater than or equal to the second preset time t2, or the temperature Tx in the space where the second heat exchanger 22 is to perform heat exchange is lower than the set temperature value Ts-ΔT1, the pre-cooling mode is exited; the first capillary tube 31 in the system is switched to the second capillary tube 32, and the oil return mode is entered. At this time, the first compressor 11 maintains the operation at the maximum frequency.

[0114] 2) The first compressor 11 is turned on, and the refrigeration system operates in the refrigeration mode. The cumulative startup operation time of the first compressor 11 is less than the first preset time t1. The temperature Tx in the space where the second heat exchanger 22 is to perform heat exchange does not reach the set temperature value Ts within the set time. The first capillary tube 31 is switched to the second capillary tube 32, and the oil return mode is entered. At this time, the first compressor 11 operates at the maximum frequency.

[0115] In the above two cases, enter the oil return mode. When the operation time of the first compressor 11 at the maximum frequency is greater than or equal to the third preset time t3, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger 22 is greater than the set temperature value Ts + ΔT2, then exit the oil return mode, and the second capillary 32 in the system is switched back to the first capillary 31, and enter the refrigeration mode.

[0116] Some specific embodiments of the refrigeration system will be described in detail below.

[0117] Reference Figure 1 , the refrigeration system includes a high-temperature stage component and a low-temperature stage component.

[0118] The high-temperature stage component includes a second compressor 12, a third heat exchanger 23, a second dryer filter 82, and a throttling member 7. Along the flow direction of the refrigerant, the second compressor 12, the third heat exchanger 23, the throttling member 7, the first heat exchanger 21, and the second compressor 12 are connected in sequence. The third heat exchanger 23 serves as a condenser.

[0119] The low-temperature stage component includes a first compressor 11, an oil separator 9, a first dryer filter 81, a throttling assembly 3, a second heat exchanger 22, a first control valve 51, and a second control valve 52. Along the flow direction of the refrigerant, the first compressor 11, the first heat exchanger 21, the throttling assembly 3, the second heat exchanger 22, and the first compressor 11 are connected in sequence. The second heat exchanger 22 serves as an evaporator.

[0120] The high-temperature stage component and the low-temperature stage component share the first heat exchanger 21. The first heat exchanger 21 serves as an evaporator in the high-temperature stage component and as a condenser in the low-temperature stage component.

[0121] Among them, the lubricating oil accumulated in the oil separator 9 flows into the first compressor 11 through the oil return pipeline.

[0122] The throttling assembly 3 in the low-temperature stage component includes a first capillary 31 and a second capillary 32. The first control valve 51 controls the first capillary 31 to be in a working state or a non-working state. The second control valve 52 controls the second capillary 32 to be in a working state or a non-working state.

[0123] Reference Figure 2 , the situations of converting from the refrigeration mode to the oil return mode in the anti-blocking method of the refrigeration system include the following two.

[0124] 1) The first compressor 11 is started and operates at the target frequency. At this time, the first capillary 21 is connected to the system and in a working state, and the second capillary 32 is disconnected from the system and in a non-working state, and the refrigeration system is in the refrigeration mode.

[0125] When the cumulative startup running time of the first compressor 11 is greater than or equal to the first preset time t1, a certain amount of lubricating oil accumulates in the second heat exchanger 22. In order to reduce the influence of the oil return process on the temperature Tx in the space where the second heat exchanger 22 needs to perform heat exchange, the first compressor 11 operates at the maximum frequency and enters the pre-cooling mode.

[0126] When the running time of the first compressor 11 at the maximum frequency is greater than or equal to the second preset time t2, or the temperature Tx in the space where the second heat exchanger 22 needs to perform heat exchange is lower than the set temperature value Ts - △T1, the pre-cooling mode is exited and the oil return mode is started. At this time, the first capillary tube 21 connected to the system is disconnected and in a non-operating state, and the second capillary tube 32 is switched to be connected to the system and in an operating state.

[0127] 2) The first compressor 11 is started and operates at the target frequency. At this time, the first capillary tube 21 is connected to the system and in an operating state, and the second capillary tube 32 is disconnected from the system and in a non-operating state. The refrigeration system is in the refrigeration mode.

[0128] When the cumulative startup running time of the first compressor 11 is less than the first preset time t1, and the temperature Tx in the space where the second heat exchanger 22 needs to perform heat exchange cannot reach the set temperature value Ts (the set temperature value Ts is extremely low) within the set time, it is determined that the lubricating oil accumulated in the second heat exchanger 22 affects the heat exchange of the second heat exchanger 22, and then the oil return mode is entered. At this time, the first capillary tube 21 connected to the system is disconnected and in a non-operating state, and the second capillary tube 32 is switched to be connected to the system and in an operating state.

[0129] In the above two cases, after the refrigeration system is switched from the refrigeration mode to the oil return mode, the first compressor 11 operates at the maximum frequency. When the running time of the first compressor 11 at the maximum frequency is greater than or equal to the third preset time t3, or the temperature Tx in the space where the second heat exchanger 22 needs to perform heat exchange rises, Tx > Ts + △T2, the oil return mode is exited and the refrigeration mode is entered. At this time, the first compressor 11 operates at the target frequency, the first capillary tube 21 is connected to the system and in an operating state, and the second capillary tube 32 is disconnected from the system and in a non-operating state.

[0130] In some embodiments, after entering the working mode in which the first capillary tube 31 is in the operating state, the second capillary tube 32 is in the non-operating state, and the first compressor 11 operates at the target frequency, it is judged whether the temperature X in the space where the second heat exchanger 22 needs to perform heat exchange can reach the set temperature value Ts within the set time, and the set time can be set as needed.

[0131] The set time can be divided according to the ambient temperature Ta and the set temperature value Ts.

[0132] When the ambient temperature Ta is low and the set temperature value Ts is high, the time required for the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat to reach the set temperature value Ts is short.

[0133] When the ambient temperature Ta is high and the set temperature value Ts is low, the time required for the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat to reach the set temperature is long.

[0134] Among them, the allowable set time ts for the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat to reach the set temperature value Ts is shown in the following table.

[0135]

[0136] One of the criteria for determining the entry into the oil return mode is that the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat cannot reach the set temperature value Ts within the set time ts. The set time ts varies under different ambient temperatures Ta and set temperature values Ts.

[0137] For example: If the ambient temperature Ta≥28 and the set temperature value Ts≤-83, when the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat cannot reach the set temperature value Ts within the time ts11, it indicates that there is serious oil accumulation in the second heat exchanger 22.

[0138] Based on: when the ambient temperature Ta is low and the set temperature value Ts is high, the time required for the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat to reach the set temperature value Ts is short; when the ambient temperature Ta is high and the set temperature value Ts is low, the time required for the temperature Tx in the space where the second heat exchanger 22 needs to exchange heat to reach the set temperature is long, it can be inferred that: ts11>ts12>ts13>ts14.

[0139] In some other embodiments, it is also possible to judge whether there is a large amount of lubricating oil accumulated in the second heat exchanger 22 by the outlet temperature and outlet pressure of the second heat exchanger 22.

[0140] When there is a large amount of lubricating oil accumulated in the second heat exchanger 22, the heat exchange effect is poor, the temperature at the outlet of the second heat exchanger 22 is low, and the temperature in the space where the second heat exchanger 22 needs to exchange heat is high. When the outlet temperature of the second heat exchanger 22 is lower than the preset temperature value range, it is judged that there is a large amount of lubricating oil accumulated in the second heat exchanger 22. At this time, the refrigeration system can be switched from the refrigeration mode to the oil return mode.

[0141] Of course, in order to avoid the temperature in the space where the second heat exchanger 22 needs to exchange heat from rising too much when the refrigeration system is in the oil return mode, the refrigeration system can be first switched from the refrigeration mode to the precooling mode, and then from the precooling mode to the oil return mode.

[0142] The outlet temperature and pressure of the second heat exchanger 22 can reflect the heat exchange capacity of the second heat exchanger 22, and further reflect the temperature in the space where the second heat exchanger 22 is to conduct heat exchange. Therefore, the method of judging whether a large amount of lubricating oil accumulates in the second heat exchanger 22 based on the outlet temperature and outlet pressure of the second heat exchanger 22 is similar to the method of judging the temperature in the space where the second heat exchanger 22 is to conduct heat exchange, and will not be elaborated here.

[0143] Some embodiments also provide a medical low-temperature storage box, which includes a box body and the refrigeration system in any of the above embodiments.

[0144] A storage space for accommodating articles is formed inside the box body.

[0145] The second heat exchanger 22 in the refrigeration system is configured to cool the storage space.

[0146] In some embodiments, the temperature requirement for the storage space is -80°C to -90°C.

[0147] In some embodiments, the refrigeration system further includes a temperature detector 6, and the temperature detector 6 is used to detect the temperature in the space where the second heat exchanger 22 is to conduct heat exchange. In this embodiment, the space where the second heat exchanger 22 is to conduct heat exchange is the storage space for accommodating articles formed inside the box body of the medical low-temperature storage box. The temperature detector 6 is used to detect the temperature in the storage space.

[0148] In some embodiments, the medical low-temperature storage box further includes a second compressor 12, a third heat exchanger 23, and a throttling member 7 provided outside the box body. Along the flow direction of the refrigerant, the second compressor 12, the third heat exchanger 23, the throttling member 7, the first heat exchanger 21, and the second compressor 12 are connected in sequence.

[0149] The second heat exchanger 22 is used to cool the storage space for accommodating articles formed inside the box body of the medical low-temperature storage box. The first compressor 11, the first heat exchanger 21, and the throttling assembly 3 can be provided inside the box body and located outside the storage space.

[0150] The second compressor 12, the third heat exchanger 23, and the throttling member 7 can be provided outside the box body.

[0151] Based on the above embodiments of the present disclosure, without explicit negation or conflict, the technical features of one embodiment can be beneficially combined with one or more other embodiments.

[0152] Although some specific embodiments of the present disclosure have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present disclosure. Those skilled in the art should understand that the above embodiments can be modified or some technical features can be equivalently replaced without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A refrigeration system, characterized in that, it includes a first compressor (11), a first heat exchanger (21), a throttling component (3) and a second heat exchanger (22); along the refrigerant flow direction, the first compressor (11), the first heat exchanger (21), the throttling component (3), the second heat exchanger (22) and the first compressor (11) are connected in sequence. Lubricating oil is injected into the first compressor (11), and the lubricating oil flows with the refrigerant, and part of it accumulates in the second heat exchanger (22); wherein the throttling component (3) includes a first capillary tube (31) and a second capillary tube (32) connected in parallel, the length of the first capillary tube (31) is greater than the length of the second capillary tube (32), and the first capillary tube (31) and the second capillary tube (32) are configured to be alternatively in a working state; the first capillary tube (31) is configured to make the temperature of the refrigerant passing through it lower than the pour point of the lubricating oil, and the second capillary tube (32) is configured to make the temperature of the refrigerant passing through it higher than the pour point of the lubricating oil; Under normal circumstances, the first capillary tube (31) is in a working state, and the second capillary tube (32) is in a non-working state; In the case of a blockage in the refrigeration system, the second capillary tube (32) is in a working state, and the first capillary tube (31) is in a non-working state; In the case where the blockage of the refrigeration system is removed, it is switched to the first capillary tube (31) being in a working state, and the second capillary tube (32) being in a non-working state.

2. The refrigeration system according to claim 1, characterized in that, it further includes: a first control valve (51), arranged on the pipeline where the first capillary tube (31) is located, and configured to control the first capillary tube (31) to be in a working state or a non-working state; and a second control valve (52), arranged on the pipeline where the second capillary tube (32) is located, and configured to control the second capillary tube (32) to be in a working state or a non-working state.

3. The refrigeration system according to claim 2, characterized in that, it further includes a controller (4), the controller (4) is electrically connected to the first control valve (51) and the second control valve (52), and the controller (4) is configured to control the first control valve (51) or the second control valve (52) to open, so that the first capillary tube (31) or the second capillary tube (32) is in a working state.

4. The refrigeration system according to claim 3, characterized in that, the controller (4) is configured to control the first compressor (11) to operate at a target frequency and control the first control valve (51) to open during the initial startup and operation stage of the first compressor (11).

5. The refrigeration system according to claim 4, characterized in that, it further includes a temperature detection component (6) electrically connected to the controller (4), the temperature detection component (6) is configured to detect the temperature Tx in the space where heat exchange is to be carried out by the second heat exchanger (22), and the controller (4) is configured to receive the temperature signal detected by the temperature detection component (6); The controller (4) is further configured to control the first control valve (51) to close, the second control valve (52) to open, and the first compressor (11) to operate at the maximum frequency when the cumulative operating time of the first compressor (11) < the first preset time t1 and the temperature Tx in the space > the set temperature value Ts within the set time.

6. The refrigeration system according to claim 4, wherein, it further includes a temperature detector (6) electrically connected to the controller (4), the temperature detector (6) is configured to detect the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22), and the controller (4) is configured to receive the temperature signal detected by the temperature detector (6); The controller (4) is further configured to control the first compressor (11) to operate at the maximum frequency when the cumulative operating time of the first compressor (11) ≥ the first preset time t1.

7. The refrigeration system according to claim 6, wherein, the controller (4) is further configured to control the first control valve (51) to close, the second control valve (52) to open, and the first compressor (11) to maintain operating at the maximum frequency when the operating time of the first compressor (11) at the maximum frequency ≥ the second preset time t2, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22) < the set temperature value Ts - ΔT1.

8. The refrigeration system according to claim 5 or 7, wherein, the controller (4) is configured to control the first control valve (51) to open, the second control valve (52) to close, and the first compressor (11) to operate at the target frequency when the operating time of the first compressor (11) at the maximum frequency ≥ the third preset time t3, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22) > the set temperature value Ts + ΔT2.

9. The refrigeration system according to any one of claims 1 to 5, wherein, it further includes a second compressor (12), a third heat exchanger (23), and a throttling member (7), and along the flow direction of the refrigerant, the second compressor (12), the third heat exchanger (23), the throttling member (7), the first heat exchanger (21), and the second compressor (12) are connected in sequence.

10. A medical low-temperature storage box, wherein, it includes: a box body, which forms a storage space for accommodating items therein; and the refrigeration system according to any one of claims 1 to 9, and the second heat exchanger (22) is configured to cool the storage space.

11. The medical low-temperature storage box according to claim 10, wherein, it further includes a second compressor (12), a third heat exchanger (23), and a throttling member (7) provided outside the box body, and along the flow direction of the refrigerant, the second compressor (12), the third heat exchanger (23), the throttling member (7), the first heat exchanger (21), and the second compressor (12) are connected in sequence.

12. A method for preventing blockage of the refrigeration system according to any one of claims 1 to 9, which includes the following steps: The first compressor (11) is turned on, entering a working mode in which the first capillary tube (31) is in a working state and the second capillary tube (32) is in a non-working state, and the first compressor (11) operates at a target frequency. In the case of a blockage in the refrigeration system, it switches to a working mode in which the second capillary tube (32) is in a working state, the first capillary tube (31) is in a non-working state, and the first compressor (11) operates at the maximum frequency. In the case of the blockage in the refrigeration system being removed, it switches to a working mode in which the first capillary tube (31) is in a working state, the second capillary tube (32) is in a non-working state, and the first compressor (11) operates at a target frequency.

13. The method for preventing blockage of the refrigeration system according to claim 12 further includes a method for determining that the refrigeration system is blocked, which includes the following steps: After entering the working mode in which the first capillary tube (31) is in a working state, the second capillary tube (32) is in a non-working state, and the first compressor (11) operates at a target frequency: When the cumulative operating time of the first compressor (11) < the first preset time t1; and the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22) > the set temperature value Ts within the set time, it is determined that the refrigeration system is blocked.

14. The method for preventing blockage of the refrigeration system according to claim 12 further includes a method for determining that the refrigeration system is blocked, which includes the following steps: After entering the working mode in which the first capillary tube (31) is in a working state, the second capillary tube (32) is in a non-working state, and the first compressor (11) operates at a target frequency: When the cumulative operating time of the first compressor (11) ≥ the first preset time t1, it is determined that the refrigeration system is blocked.

15. For the method for preventing blockage of the refrigeration system according to claim 14, after determining that the refrigeration system is blocked, first control the first compressor (11) to operate at the maximum frequency for precooling; when the operating time of the first compressor (11) at the maximum frequency ≥ the second preset time t2, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22) < the set temperature value Ts - ΔT1, switch to a working mode in which the second capillary tube (32) is in a working state, the first capillary tube (31) is in a non-working state, and the first compressor (11) operates at the maximum frequency.

16. The method for preventing blockage of the refrigeration system according to any one of claims 12 to 15 further includes a method for determining that the blockage of the refrigeration system is removed, which includes the following steps: After entering the working mode in which the second capillary tube (32) is in a working state, the first capillary tube (31) is in a non-working state, and the first compressor (11) operates at the maximum frequency; When the operating time of the first compressor (11) at the maximum frequency ≥ the third preset time t3, or the temperature Tx in the space where heat exchange is to be performed by the second heat exchanger (22) > the set temperature value Ts + ΔT2, it is determined that the blockage of the refrigeration system is removed.

Images