Fluorine pump compression refrigeration system and control method thereof

Abstract

The application provides a fluorine pump compression refrigeration system and a control method thereof. The system comprises an evaporator, a condenser and a throttling element. The throttling element is connected between the outlet of the condenser and the inlet of the evaporator. A liquid storage tank is connected between the condenser and the throttling element. The fluorine pump compression refrigeration system further comprises a refrigerant adjusting tank. The top of the refrigerant adjusting tank is in controllable on-off communication with the outlet of the condenser through a first pipeline. The bottom of the refrigerant adjusting tank is in controllable on-off communication with the top of the liquid storage tank through a second pipeline or in controllable on-off communication with the liquid inlet of the throttling element through the second pipeline. The application controls the amount of refrigerant entering and leaving the refrigerant adjusting tank by controlling the on-off time length of the first pipeline and the second pipeline or the inner diameter of the two pipelines, realizes the migration of the refrigerant, effectively prevents the excessive filling amount of the refrigerant in the system from causing the retention of liquid accumulation, prevents the excessive refrigerant in the refrigeration system from occupying the heat exchange pipeline in the heat exchanger, and improves the heat exchange efficiency.

Description

Technical Field

[0001] This invention belongs to the field of air conditioning technology, specifically relating to a fluorine pump compression refrigeration system and its control method. Background Technology

[0002] With the widespread application of 4G and the gradual popularization of 5G, the heat generated by various data processing devices is increasing, and data centers are placing higher and higher demands on the cooling capacity and energy efficiency of their air conditioning equipment.

[0003] Using outdoor natural cold sources during transitional seasons and cold winters to cool data centers can significantly reduce the operating costs of air conditioning equipment. A common approach is to use refrigerant pump air conditioning. In winter, the refrigerant pump is activated, the compressor is stopped, and the refrigerant pump drives the refrigerant to achieve heat pipe cooling, greatly reducing equipment operating costs. The refrigerant pump compression refrigeration system is a composite system; the refrigerant pump heat pipe system shares the evaporator and condenser with the compression refrigeration system, as well as some shared refrigerant piping and system components.

[0004] Because the heat load of data centers fluctuates with user activity and seasonal changes, more and more data center air conditioners are now using inverter technology to cope with these fluctuations and ensure the data center's constant temperature and humidity requirements. However, changes in the compressor frequency of the refrigeration system can alter the optimal refrigerant circulation volume. Generally, higher frequencies require a larger refrigerant circulation volume. If the optimal refrigerant charge is designed and developed for 100% load, the optimal refrigerant charge for 75% or 50% load, or other low-frequency operating conditions, will be less. Consequently, refrigerant may accumulate inside the unit under low-frequency conditions, and this accumulation at the bottom of the heat exchanger hinders heat exchange.

[0005] Meanwhile, in refrigerant pump mode, considering the liquid height requirements at the refrigerant pump inlet, the required refrigerant charge is usually relatively large. Therefore, under actual operating conditions, the refrigerant pump compression refrigeration system may experience refrigerant liquid retention. It is necessary to consider migrating the retained refrigerant to the liquid receiver tank. In high-frequency compression refrigeration mode or refrigerant pump refrigeration mode, the retained refrigerant liquid in the liquid receiver tank should be released as soon as possible to participate in the system circulation. Summary of the Invention

[0006] Therefore, the present invention provides a fluorine pump compression refrigeration system and its control method, which can solve the technical problem of refrigerant redundancy caused by the difference in refrigerant charge amount required under different operating conditions in the prior art fluorine pump compression refrigeration system.

[0007] To address the aforementioned problems, this invention provides a refrigerant pump compression refrigeration system, comprising an evaporator, a condenser, and a throttling element. The throttling element is connected between the outlet of the condenser and the inlet of the evaporator. A liquid storage tank is connected between the condenser and the throttling element. The refrigerant pump compression refrigeration system further includes a refrigerant regulating tank. The top of the refrigerant regulating tank is controllably connected to the outlet of the condenser via a first pipeline, and the bottom of the refrigerant regulating tank is controllably connected to the top of the liquid storage tank via a second pipeline, or controllably connected to the inlet of the throttling element via the second pipeline.

[0008] In some embodiments, an electromagnetic on / off valve is connected in series on the second pipeline; and / or, the bottom height of the refrigerant regulating tank is higher than the top height of the liquid storage tank, so that the refrigerant in the refrigerant regulating tank can flow into the liquid storage tank under its own weight.

[0009] In some embodiments, the refrigerant pump compression refrigeration system further includes a flow path switching valve, which has a first state connecting the outlet of the condenser to the top of the refrigerant regulating tank and a second state connecting the outlet of the condenser to the top of the liquid storage tank. The flow path switching valve can be controlled to switch between the first state and the second state to achieve controllable on / off connection between the first pipeline and the outlet of the condenser.

[0010] In some embodiments, the fluorine pump compression refrigeration system further includes a fluorine pump, the inlet of which is connected to the bottom of the storage tank, the outlet of which is connected to the inlet of the throttling element, and a third pipeline connecting the inlet of the fluorine pump and the inlet of the throttling element. A first one-way valve is connected in series on the third pipeline, the one-way direction of which is from the inlet side of the fluorine pump to the inlet side of the throttling element; and / or, the flow path switching valve is a solenoid three-way valve.

[0011] In some embodiments, the refrigerant pump compression refrigeration system further includes a compressor and a fourth pipeline. The compressor's suction port is connected to the evaporator's outlet, and the compressor's discharge port is connected to the condenser's inlet. The fourth pipeline is connected between the compressor's suction port and discharge port, and a second one-way valve is connected in series on the fourth pipeline. The one-way direction of the second one-way valve is from the compressor's suction port side to the compressor's discharge port side.

[0012] In some embodiments, the refrigerant regulating tank is equipped with a level gauge for detecting the real-time liquid level of the refrigerant in the tank; and / or, the refrigerant regulating tank is equipped with a temperature sensor for detecting the real-time temperature of the refrigerant in the tank.

[0013] The present invention also provides a control method for the above-described fluorine pump compression refrigeration system, comprising the following steps:

[0014] Obtain the operating mode of the fluorine pump compression refrigeration system;

[0015] The operation mode is used to control the on / off state of the electromagnetic on / off valve, the state switching state of the flow path switching valve, and the start / stop of the compressor and the refrigerant pump.

[0016] In some implementations, when the operating mode is the refrigerant pump refrigeration mode, the solenoid on / off valve is controlled to open, the flow path switching valve is controlled to be in the first state, the compressor is controlled to stop operating or remain in a stopped state, and the refrigerant pump is controlled to operate after the refrigerant in the refrigerant regulating tank has completely flowed into the liquid receiver.

[0017] In some embodiments, when the operating mode is compression refrigeration mode, the compressor is controlled to operate and the real-time operating frequency of the compressor is obtained. Based on the obtained real-time operating frequency, the target liquid level height h of the refrigerant in the refrigerant regulating tank corresponding to the real-time operating frequency is obtained. The on / off state of the electromagnetic on / off valve and the state switching of the flow path switching valve are controlled to adjust the real-time liquid level height of the refrigerant in the refrigerant regulating tank to the target liquid level height h.

[0018] In some embodiments, when the real-time refrigerant level in the refrigerant regulating tank is lower than the target level h, the solenoid on / off valve is controlled to open, the flow path switching valve is controlled to be in the first state, and the on-time of the solenoid on / off valve is controlled to be shorter than the duration of the first state, until the real-time refrigerant level rises to the target level h, at which point the flow path switching valve is controlled to switch to the second state, and the solenoid on / off valve is controlled to close; or,

[0019] When the real-time liquid level of the refrigerant in the refrigerant regulating tank is higher than the target liquid level h, the solenoid on / off valve is controlled to open, the flow path switching valve is controlled to be in the first state, and the conduction time of the solenoid on / off valve is controlled to be longer than the maintenance time of the first state, until the real-time liquid level drops to the target liquid level h, the flow path switching valve is controlled to switch to the second state, and the solenoid on / off valve is controlled to close.

[0020] In some embodiments, the target liquid level height h is obtained in the following manner:

[0021] Obtain the optimal refrigerant charge m1 for the system cycle corresponding to the real-time operating frequency, and calculate the amount of refrigerant m2 that needs to be stored in the refrigerant regulating tank, m2 = m - m1, where m is the total amount of refrigerant in the system;

[0022] The real-time temperature t and / or real-time saturation pressure inside the refrigerant regulating tank are obtained, and the liquid refrigerant density ρ corresponding to the real-time temperature t and / or real-time saturation pressure is obtained according to the refrigerant parameters pre-stored in the controller.

[0023] The target liquid level height h is calculated using the formula h = m² / (ρS), where S is the cross-sectional area of ​​the storage space of the refrigerant regulating tank.

[0024] The fluorine pump compression refrigeration system and its control method provided by the present invention have the following beneficial effects:

[0025] The amount of refrigerant entering and exiting the refrigerant regulating tank can be controlled by adjusting the on / off time of the first and second pipelines or the inner diameter of the two pipelines. This allows for the transfer of refrigerant stored in the regulating tank to replenish the system circulation, increasing the refrigerant charge in the system circulation, or the transfer and storage of excess refrigerant in the system circulation in the refrigerant regulating tank. This effectively prevents excessive refrigerant charge in the system from causing liquid accumulation and prevents excessive refrigerant from occupying the heat exchange pipes in the heat exchanger, thus improving heat exchange efficiency. In this way, the technical solution of the present invention enables controllable adjustment of the refrigerant circulation volume required in the refrigeration system, meeting the optimal system circulation volume requirements. It solves the refrigerant redundancy problem caused by the difference in refrigerant charge volume required under different operating conditions in the prior art of fluorine pump compression refrigeration systems, so as to meet the optimal circulation volume required by the refrigeration system under various operating conditions as much as possible. Attached Figure Description

[0026] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the accompanying drawings used in the description of the embodiments or the prior art will be briefly introduced below. The drawings described below are merely exemplary, and those skilled in the art can derive other embodiments based on the provided drawings without creative effort.

[0027] Figure 1 This is a schematic diagram of the principle of the fluorine pump compression refrigeration system according to an embodiment of the present invention;

[0028] Figure 2 This is a schematic diagram of the principle of a fluorine pump compression refrigeration system according to another embodiment of the present invention.

[0029] The attached figures are labeled as follows:

[0030] 11. Evaporator; 111. Indoor fan; 12. Condenser; 121. Outdoor fan; 13. Throttling element; 14. Liquid receiver; 15. Refrigerant pump; 16. Compressor; 2. Refrigerant regulating tank; 21. Level gauge; 3. Flow path switching valve; 101. First pipeline; 102. Second pipeline; 1021. Solenoid on / off valve; 103. Third pipeline; 1031. First check valve; 104. Fourth pipeline; 1041. Second check valve. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0033] For ease of description, spatial relative terms such as "above," "on top of," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation beyond the orientation of the device as described in the figures. For example, if the device in the figures were inverted, a device described as "above" or "on top of" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90° or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0034] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0035] See Figure 1 and Figure 2 As shown, according to an embodiment of the present invention, a refrigerant pump compression refrigeration system is provided, including an evaporator 11, a condenser 12, and a throttling element 13 (e.g., an electronic expansion valve). The throttling element 13 is connected between the outlet of the condenser 12 and the inlet of the evaporator 11. A liquid storage tank 14 is connected between the condenser 12 and the throttling element 13. The refrigerant pump compression refrigeration system also includes a refrigerant regulating tank 2. The top of the refrigerant regulating tank 2 is controllably connected to the outlet of the condenser 12 via a first pipe 101. The bottom of the refrigerant regulating tank 2 is controllably connected to the top of the liquid storage tank 14 via a second pipe 102, or controllably connected to the inlet of the throttling element 13 via the second pipe 102. It is understood that the top of the refrigerant regulating tank 2 is its internal top space, which typically contains gaseous refrigerant. The top of the liquid storage tank 14 is its internal top space, which typically contains gaseous refrigerant.

[0036] In this technical solution, the amount of refrigerant entering and exiting the refrigerant regulating tank 2 can be controlled by adjusting the on / off time of the first pipeline 101 and the second pipeline 102 or by controlling the inner diameter of the two pipelines. This allows the refrigerant stored in the refrigerant regulating tank 2 to be transferred to replenish the system circulation, increasing the refrigerant charge in the system circulation, or to transfer and store excess refrigerant in the system circulation in the refrigerant regulating tank 2. This effectively prevents excessive refrigerant charge in the system from causing liquid accumulation and prevents excessive refrigerant from occupying the heat exchange pipes in the heat exchanger, thus improving heat exchange efficiency. In this way, the technical solution of the present invention enables controllable adjustment of the refrigerant circulation volume required in the refrigeration system, meeting the optimal system circulation volume requirements, and solving the refrigerant redundancy problem caused by the difference in refrigerant charge volume required under different operating conditions in the prior art of fluorine pump compression refrigeration systems, so as to meet the optimal circulation volume required by the refrigeration system under various operating conditions as much as possible.

[0037] In one specific embodiment, an electromagnetic on / off valve 1021 is connected in series on the second pipeline 102, so that the second pipeline 102 can be opened and closed by controlling the energization and de-energization of the aforementioned electromagnetic on / off valve 1021. The control is simple and the implementation cost is low. In a preferred embodiment, the electromagnetic on / off valve 1021 is a normally closed valve when de-energized, that is, it opens for flow when energized and cuts off the flow when de-energized.

[0038] In another preferred embodiment, the bottom height of the refrigerant regulating tank 2 is higher than the top height of the liquid storage tank 14, so that the refrigerant in the refrigerant regulating tank 2 can flow into the liquid storage tank 14 under its own weight.

[0039] In this technical solution, the refrigerant regulating tank 2 is positioned relatively high. When the electromagnetic on / off valve 1021 in the second pipeline 102 is opened, the liquid refrigerant in the refrigerant regulating tank 2 will enter the lower-positioned liquid storage tank 14 under its own weight, thereby increasing the refrigerant charge in the system circulation. It should be noted that this technical solution utilizes only the relative height difference between the refrigerant regulating tank 2 and the liquid storage tank 14, employing the weight of the liquid refrigerant for migration. The structure is particularly simple, requiring no additional pumping mechanisms, further reducing manufacturing costs.

[0040] In some embodiments, the refrigerant pump compression refrigeration system further includes a flow path switching valve 3, which has a first state connecting the outlet of the condenser 12 to the top of the refrigerant regulating tank 2 and a second state connecting the outlet of the condenser 12 to the top of the liquid storage tank 14. The flow path switching valve 3 can be controlled to switch between the first state and the second state to achieve controllable on / off connection between the first pipeline 101 and the outlet of the condenser 12.

[0041] In this technical solution, when the flow path switching valve 3 is in the first state, the refrigerant (mainly liquid) flowing out of the condenser 12 is introduced into the refrigerant regulating tank 2. At this time, the solenoid on / off valve 1021 is controlled to be open to ensure the smooth flow or storage of liquid refrigerant in the refrigerant regulating tank 2. When the flow path switching valve 3 is in the second state, the refrigerant flowing out of the condenser 12 is guided into the liquid storage tank 14 to participate in the system circulation. At this time, the solenoid on / off valve 1021 can be in the cut-off state.

[0042] Generally speaking, any valve or valve assembly capable of switching between the aforementioned first and second states can be referred to as the aforementioned flow path switching valve 3 of the present invention. For example, it can be implemented by combining multiple two-way valves. As a preferred embodiment, the flow path switching valve 3 is a three-way valve, specifically a two-position three-way solenoid valve, which can significantly simplify system design. See details. Figure 1 and Figure 2As shown, when the two-position three-way solenoid valve is energized, OM is closed and ON is connected; when the power is off, OM is connected and ON is closed. Since the redundancy of refrigerant adjustment through refrigerant regulating tank 2 is relatively rare and the time required is relatively short, and in the refrigerant pump refrigeration mode, the refrigerant in refrigerant regulating tank 2 needs to be migrated to liquid storage tank 14 or the system to participate in circulation, the probability of the ON channel of the three-way valve being open is relatively small and the probability of the OM channel being open is very high. Therefore, the preferred three-way valve is one in which OM is connected and ON is closed when the power is off, which can save energy and improve the service life of the three-way valve.

[0043] In some embodiments, the refrigerant pump compression refrigeration system further includes a refrigerant pump 15, the inlet of which is connected to the bottom of the liquid storage tank 14, and the outlet of which is connected to the inlet of the throttling element 13. A third pipeline 103 is also connected between the inlet of the refrigerant pump 15 and the inlet of the throttling element 13. A first check valve 1031 is connected in series on the third pipeline 103. The unidirectional flow direction of the first check valve 1031 is from the inlet side of the refrigerant pump 15 to the inlet side of the throttling element 13. It is understood that when the refrigerant pump 15 is running, the first check valve 1031 will block the flow of refrigerant through the third pipeline 103 under the action of reverse pressure difference.

[0044] In this technical solution, the automatic switching between the compression refrigeration mode and the refrigeration mode of the refrigeration pump compression refrigeration system of the present invention can be realized through the third pipeline 103 connected in parallel with the refrigeration pump 15. The structure is simple and easy to implement.

[0045] In some embodiments, the refrigerant pump compression refrigeration system further includes a compressor 16 and a fourth pipeline 104. The suction port of the compressor 16 is connected to the outlet port of the evaporator 11, and the discharge port of the compressor 16 is connected to the inlet port of the condenser 12. The fourth pipeline 104 is connected between the suction port and the discharge port of the compressor 16, and a second one-way valve 1041 is connected in series on the fourth pipeline 104. The one-way flow direction of the second one-way valve 1041 is from the suction port side of the compressor 16 to the discharge port side of the compressor 16. When the compressor 16 is running, the second one-way valve 1041 will stop the flow of refrigerant through the fourth pipeline 104 under the action of reverse pressure difference.

[0046] In some embodiments, the refrigerant regulating tank 2 is provided with a level gauge 21 for detecting the real-time liquid level of the refrigerant in the refrigerant regulating tank 2; and / or, the refrigerant regulating tank 2 is provided with a temperature sensor (not shown in the figure) for detecting the real-time temperature of the refrigerant in the refrigerant regulating tank 2.

[0047] Thus, it can be understood that, compared to the refrigerant pump compression refrigeration system in related technologies, the technical solution of the present invention only requires the addition of one solenoid valve (i.e., the aforementioned solenoid on / off valve 1021), one three-way valve (i.e., the aforementioned solenoid three-way valve), and one regulating tank (i.e., the aforementioned refrigerant regulating tank 2). This allows for redundant regulation of the refrigerant. In compression refrigeration mode, if the ON channel opening time of the three-way valve (i.e., the duration of the first state) is greater than the opening time of the solenoid valve, excess refrigerant can be stored in the regulating tank at a higher level, preventing excessive refrigerant from occupying the heat exchange pipes in the heat exchanger within the refrigeration system. Conversely, the refrigerant in the regulating tank can be transferred out to replenish the liquid storage tank or participate in the circulation within the system. In refrigerant pump refrigeration mode, opening the solenoid valve utilizes gravity to transfer the refrigerant in the regulating tank back to the liquid storage tank or participate in the circulation within the system, ensuring sufficient refrigerant liquid level in the liquid storage tank and preventing excessively low pressure at the liquid suction end of the refrigerant pump from causing cavitation. This technical solution provides precise and reliable regulation of redundant refrigerant, fully utilizes the on / off time difference control of the three-way valve and solenoid valve, and leverages the effect of liquid gravity. It requires few additional components and has simple connecting pipes.

[0048] It should be noted that, for details please refer to [link / reference]. Figure 1 The second pipe 102 in the figure is connected to the top area of ​​the liquid storage tank 14, which enables the refrigerant to be moved out or in the refrigerant regulating tank 2 of the present invention. However, this requires necessary modifications to the structure of the liquid storage tank 14 in the prior art, and the cost of the modification is relatively high. (See also...) Figure 2 As shown in the figure, the second pipeline 102 is connected to the pipeline between the first one-way valve 1031 and the throttling element 13. In the actual implementation, only a three-way pipe needs to be added, without modifying the structure of the liquid storage tank 14, which is simpler, easier and cheaper.

[0049] According to an embodiment of the present invention, a control method for the fluorine pump compression refrigeration system as described above is also provided, comprising the following steps:

[0050] Obtain the operating mode of the fluorine pump compression refrigeration system;

[0051] The operation mode controls the opening and closing of the electromagnetic on / off valve 1021, the state switching of the flow path switching valve 3, and the start and stop of the compressor 16 and the fluorine pump 15.

[0052] Specifically, when the operating mode is the refrigerant pump refrigeration mode, the solenoid on / off valve 1021 is controlled to open, the flow path switching valve 3 is controlled to be in the first state, the compressor 16 is controlled to stop running or remain in a stopped state, and after the refrigerant in the refrigerant regulating tank 2 has completely flowed into the liquid storage tank 14, the solenoid on / off valve 1021 is controlled to cut off and the refrigerant pump 15 is controlled to run.

[0053] That is, when the system is running in refrigerant pump refrigeration mode, before controlling the refrigerant pump 15 to operate, the solenoid on / off valve 1021 is first opened, and the flow path switching valve 3 is controlled to be in the first state. This allows the liquid refrigerant in the refrigerant regulating tank 2 to migrate back to the liquid storage tank 14 under its own weight. Then, the refrigerant pump 15 is controlled to operate in refrigerant pump refrigeration mode. This ensures that there is sufficient refrigerant liquid level in the liquid storage tank 14, preventing the refrigerant pump from cavitating due to excessively low pressure at the liquid suction end (i.e., the liquid inlet) of the refrigerant pump 15. When the refrigerant pump 15 is running, it is preferable to switch the flow path switching valve 3 to the second state (e.g., de-energize) and de-energize the solenoid on / off valve 1021 to stop the flow.

[0054] In some embodiments, when the operating mode is compression refrigeration mode, the compressor 16 is controlled to operate and the real-time operating frequency of the compressor 16 is obtained. Based on the obtained real-time operating frequency, the target liquid level height h of the refrigerant in the refrigerant regulating tank 2 corresponding to the real-time operating frequency is obtained. The electromagnetic on / off valve 1021 is controlled to open and close, and the state of the flow path switching valve 3 is switched so that the real-time liquid level height of the refrigerant in the refrigerant regulating tank 2 is adjusted to the target liquid level height h.

[0055] In this technical solution, when the system is running in compression refrigeration mode, the corresponding target liquid level height h is obtained according to the real-time operating frequency of the compressor 16, and the real-time liquid level height of the refrigerant in the refrigerant regulating tank 2 is controlled and adjusted to be at the corresponding target liquid level height h, thereby ensuring that the refrigerant charge in the system matches each real-time operating frequency, that is, it is at the optimal charge, and meets the requirements of the best system circulation volume.

[0056] Specifically, when the real-time refrigerant level in the refrigerant regulating tank 2 is lower than the target level h, it indicates that there is too much refrigerant circulating in the system. At this time, the electromagnetic on / off valve 1021 is opened, the flow path switching valve 3 is in the first state, and the on-time of the electromagnetic on / off valve 1021 is shorter than the duration of the first state. This utilizes the principle of more in and less out to move excess refrigerant from the system circulation into the refrigerant regulating tank 2. This continues until the real-time level rises to the target level h. Then, the flow path switching valve 3 is switched to the second state, and the electromagnetic on / off valve 1021 is opened to prevent excessive refrigerant from circulating in the system, thus preventing liquid accumulation and improving heat exchange efficiency. Alternatively...

[0057] When the real-time liquid level of the refrigerant in the refrigerant regulating tank 2 is higher than the target liquid level h, it indicates that there is too little refrigerant participating in the circulation in the system. At this time, the solenoid on / off valve 1021 is controlled to open, the flow path switching valve 3 is controlled to be in the first state, and the conduction time of the solenoid on / off valve 1021 is controlled to be longer than the maintenance time of the first state, so as to release the refrigerant stored in the refrigerant regulating tank 2 to participate in the system circulation by using the principle of less inflow and more outflow, thereby increasing the refrigerant charge of the system until the real-time liquid level drops to the target liquid level h. Then, the flow path switching valve 3 is controlled to switch to the second state, and the solenoid on / off valve 1021 is controlled to close.

[0058] This enables dynamic adjustment of the refrigerant within the system during compression refrigeration mode, ensuring that the refrigerant charge meets the optimal system circulation requirements.

[0059] In some embodiments, the target liquid level height h is obtained as follows: The optimal refrigerant charge m1 corresponding to the real-time operating frequency (pre-stored in the controller) is obtained, and the amount of refrigerant m2 to be stored in the refrigerant regulating tank 2 is calculated, where m2 = m - m1, and m is the total refrigerant charge in the system; the real-time temperature t and / or real-time saturation pressure in the refrigerant regulating tank 2 are obtained, and the liquid refrigerant density ρ corresponding to the real-time temperature t and / or real-time saturation pressure is determined according to the refrigerant parameters pre-stored in the controller; the target liquid level height h is calculated according to the formula h = m2 / (ρS), where S is the cross-sectional area of ​​the storage space in the refrigerant regulating tank 2. All the aforementioned physical parameters can be expressed in SI units. In a specific embodiment, the refrigerant regulating tank 2 is a cylinder with equal upper and lower diameters, i.e., all cross-sectional areas S are equal, which further simplifies the acquisition of h.

[0060] In this technical solution, the optimal refrigerant charge m1 corresponding to the real-time operating frequency is pre-stored in the controller to infer the amount of refrigerant to be stored in the refrigerant regulating tank 2, and then the corresponding target liquid level height is obtained by calculating the relevant physical parameters. This method is simple and reliable.

[0061] The following combination Figure 1 The technical solution of the present invention is further described as follows:

[0062] A) Compression refrigeration mode - the refrigerant pump (i.e., the aforementioned refrigerant pump 15, the same below) is off, and the compressor (i.e., the aforementioned compressor 16, the same below) is on. Because the second one-way valve 1041 cannot be opened at this time due to the reverse pressure difference between its two ends; the main circulation path of the refrigerant is: compressor → condenser (i.e., the aforementioned condenser 12, the same below) → three-way valve OM (i.e., the aforementioned second state, the same below) → liquid receiver (i.e., the aforementioned liquid receiver 14, the same below) → first one-way valve 1031 → throttle valve → evaporator → compressor.

[0063] In compression refrigeration mode, when the compressor frequency decreases, the required system circulation volume typically decreases, necessitating the transfer of some excess refrigerant to the regulating tank: The three-way valve is energized to open the ON channel (i.e., the aforementioned first state, hereinafter the same) / the OM channel is closed for duration t1. Then, the solenoid valve (i.e., the aforementioned solenoid on / off valve 1021, hereinafter the same) is opened for duration t2 < t1. When the liquid level in the regulating tank reaches height h (i.e., the aforementioned target liquid level height h, hereinafter the same), the three-way valve and the solenoid valve are de-energized, closing the ON channel, allowing the refrigerant liquid at the condenser outlet to re-enter the storage tank through the OM channel. The liquid tank is responsible for regulating and controlling the refrigerant. When the compressor frequency increases, the required system circulation volume usually increases, necessitating the refrigerant in the regulating tank to participate in the system circulation: the solenoid valve is opened for a duration of t3, and then the ON channel of the three-way valve is opened for a duration of t4 < t3. Under the action of gravity, the liquid refrigerant in the regulating tank flows into the liquid receiver tank or returns to the system to participate in the circulation through the solenoid valve. When the liquid level h in the regulating tank drops to the corresponding high frequency of the compressor, the solenoid valve is closed and the ON channel of the three-way valve is closed / the OM channel is opened, thus completing the refrigerant migration control.

[0064] B) Refrigerant pump refrigeration mode - when the refrigerant pump is on and the compressor is off, the three-way valve will open the OM channel / close the ON channel when the power is off, because the first one-way valve 1031 cannot be opened due to the reverse pressure difference between its two ends; the main circulation path of the refrigerant is: refrigerant pump → expansion valve → evaporator → second one-way valve 1041 → condenser → three-way valve OM → liquid receiver → refrigerant pump.

[0065] Because the refrigerant pump mode requires the largest amount of refrigerant (as explained in the background section, the main reason is to increase the liquid level in the receiver tank, ensuring the safety of the refrigerant pump's suction and preventing cavitation), all the refrigerant liquid in the regulating tank needs to be transferred into the system to participate in circulation. At this time, the solenoid valve is energized to open and the ON channel of the three-way valve is opened / OM channel is closed. The refrigerant liquid in the regulating tank enters the receiver tank or the system pipeline under the action of gravity to participate in circulation. When the level gauge and / or level sensor detect that the liquid level h in the regulating tank is 0, the solenoid valve is de-energized and the ON channel is closed / OM channel is opened, completing the refrigerant liquid transfer control in the regulating tank. Then, the refrigerant pump is started to operate in refrigerant pump refrigeration mode.

[0066] It will be readily understood by those skilled in the art that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0067] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the technical principles of the present invention, and these improvements and modifications should also be considered within the protection scope of the present invention.

Claims

1. A fluorine pump compression refrigeration system, comprising an evaporator (11), a condenser (12), and a throttling element (13), wherein the throttling element (13) is connected between the outlet of the condenser (12) and the inlet of the evaporator (11), and a liquid storage tank (14) is connected between the condenser (12) and the throttling element (13), characterized in that, It also includes a refrigerant regulating tank (2), the top of which is connected to the outlet of the condenser (12) via a first pipe (101), and the bottom of which is connected to the top of the liquid storage tank (14) via a second pipe (102) or via the second pipe (102) to the inlet of the throttling element (13).

2. The fluorine pump compression refrigeration system according to claim 1, characterized in that, An electromagnetic on / off valve (1021) is connected in series on the second pipeline (102); and / or, the bottom height of the refrigerant regulating tank (2) is higher than the top height of the liquid storage tank (14), so that the refrigerant in the refrigerant regulating tank (2) can flow into the liquid storage tank (14) under its own weight.

3. The fluorine pump compression refrigeration system according to claim 2, characterized in that, It also includes a flow path switching valve (3), which has a first state connecting the outlet of the condenser (12) to the top of the refrigerant regulating tank (2) and a second state connecting the outlet of the condenser (12) to the top of the liquid storage tank (14). The flow path switching valve (3) can be controlled to switch between the first state and the second state to realize the controllable on / off connection between the first pipeline (101) and the outlet of the condenser (12).

4. The fluorine pump compression refrigeration system according to claim 3, characterized in that, It also includes a fluorine pump (15), the inlet of which is connected to the bottom of the storage tank (14), the outlet of which is connected to the inlet of the throttling element (13), and a third pipeline (103) is connected between the inlet of the fluorine pump (15) and the inlet of the throttling element (13). A first check valve (1031) is connected in series on the third pipeline (103), and the unidirectional flow direction of the first check valve (1031) is from the inlet side of the fluorine pump (15) to the inlet side of the throttling element (13); and / or, the flow path switching valve (3) is an electromagnetic three-way valve.

5. The fluorine pump compression refrigeration system according to claim 4, characterized in that, It also includes a compressor (16) and a fourth pipeline (104). The suction port of the compressor (16) is connected to the outlet of the evaporator (11), and the discharge port of the compressor (16) is connected to the inlet of the condenser (12). The fourth pipeline (104) is connected between the suction port and the discharge port of the compressor (16), and a second one-way valve (1041) is connected in series on the fourth pipeline (104). The one-way conduction direction of the second one-way valve (1041) is from the suction port side of the compressor (16) to the discharge port side of the compressor (16).

6. The fluorine pump compression refrigeration system according to claim 1, characterized in that, The refrigerant regulating tank (2) is equipped with a level gauge (21) for detecting the real-time liquid level of the refrigerant in the refrigerant regulating tank (2); and / or, the refrigerant regulating tank (2) is equipped with a temperature sensor for detecting the real-time temperature of the refrigerant in the refrigerant regulating tank (2).

7. A control method for a fluorine pump compression refrigeration system as described in claim 5, characterized in that, Includes the following steps: Obtain the operating mode of the fluorine pump compression refrigeration system; The operation mode is used to control the opening and closing of the electromagnetic on / off valve (1021), the state switching of the flow path switching valve (3), and the start and stop of the compressor (16) and the fluorine pump (15).

8. The control method according to claim 7, characterized in that, When the operating mode is the refrigerant pump refrigeration mode, the electromagnetic on / off valve (1021) is turned on, the flow path switching valve (3) is turned on to the first state, the compressor (16) is turned off or kept in the off state, and the refrigerant pump (15) is turned on after the refrigerant in the refrigerant regulating tank (2) has completely flowed into the liquid storage tank (14).

9. The control method according to claim 7, characterized in that, When the operating mode is compression refrigeration mode, the compressor (16) is controlled to operate and the real-time operating frequency of the compressor (16) is obtained. Based on the obtained real-time operating frequency, the target liquid level height h of the refrigerant in the refrigerant regulating tank (2) corresponding to the real-time operating frequency is obtained. The electromagnetic on / off valve (1021) is controlled to open and close, and the state of the flow path switching valve (3) is switched so that the real-time liquid level height of the refrigerant in the refrigerant regulating tank (2) is adjusted to the target liquid level height h.

10. The control method according to claim 9, characterized in that, When the real-time liquid level of the refrigerant in the refrigerant regulating tank (2) is lower than the target liquid level h, the solenoid on / off valve (1021) is controlled to open, the flow path switching valve (3) is controlled to be in the first state, and the on-time of the solenoid on / off valve (1021) is controlled to be shorter than the maintenance time of the first state, until the real-time liquid level rises to the target liquid level h, the flow path switching valve (3) is controlled to switch to the second state, and the solenoid on / off valve (1021) is controlled to open; or, When the real-time liquid level of the refrigerant in the refrigerant regulating tank (2) is higher than the target liquid level h, the electromagnetic on / off valve (1021) is controlled to open, the flow path switching valve (3) is controlled to be in the first state, and the conduction time of the electromagnetic on / off valve (1021) is controlled to be longer than the maintenance time of the first state, until the real-time liquid level drops to the target liquid level h, the flow path switching valve (3) is controlled to switch to the second state, and the electromagnetic on / off valve (1021) is controlled to close.

11. The control method according to claim 9, characterized in that, The target liquid level height h is obtained in the following manner: Obtain the optimal refrigerant charge m1 corresponding to the real-time operating frequency, and calculate the amount of refrigerant m2 to be stored in the refrigerant regulating tank (2), m2 = m - m1, where m is the total amount of refrigerant in the system; The real-time temperature t and / or real-time saturation pressure in the refrigerant regulating tank (2) are obtained, and the liquid refrigerant density ρ corresponding to the real-time temperature t and / or real-time saturation pressure is obtained according to the refrigerant parameters pre-stored in the controller. The target liquid level height h is calculated according to the formula h=m2 / (ρS), where S is the cross-sectional area of ​​the storage space of the refrigerant regulating tank (2).

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