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 communicated with the outlet of the evaporator through a first pipeline. The bottom of the refrigerant adjusting tank is controllably communicated with the top of the liquid storage tank through a second pipeline. The bottom of the refrigerant adjusting tank is further controllably communicated with the liquid inlet of the throttling element through a third pipeline or controllably communicated with the liquid outlet of the liquid storage tank. The migration of the refrigerant is realized by controlling the opening and closing of the second pipeline and the third pipeline, which effectively prevents the excessive filling 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 connected to the outlet of the evaporator via a first pipe. The bottom of the refrigerant regulating tank is connected to the top of the liquid storage tank via a second pipe. The bottom of the refrigerant regulating tank is also connected to the inlet of the throttling element or the outlet of the liquid storage tank via a third pipe.

[0008] In some embodiments, a first solenoid on / off valve is connected in series on the second pipeline, and a second solenoid on / off valve is connected in series on the third pipeline; and / or, a first capillary tube is connected in series on the first 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 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 fourth pipeline connecting the inlet of the fluorine pump and the inlet of the throttling element. A first check valve is connected in series on the fourth pipeline, and the unidirectional flow direction of the first check valve is from the inlet side of the fluorine pump to the inlet side of the throttling element.

[0010] In some embodiments, the refrigerant pump compression refrigeration system further includes a compressor and a fifth 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 fifth pipeline is connected between the compressor's suction port and discharge port, and a second one-way valve is connected in series on the fifth 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.

[0011] In some embodiments, an oil separator is connected in series on the pipeline between the compressor's exhaust port and the condenser, and the outlet of the oil separator's return oil pipe is connected to the compressor's intake port via a second capillary tube.

[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 opening and closing of the first and second electromagnetic on / off valves, as well as the start and stop of the compressor and the refrigerant pump.

[0016] In some embodiments, when the operating mode is the refrigerant pump refrigeration mode, the first electromagnetic on / off valve is controlled to open, 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 first electromagnetic on / off valve and the second electromagnetic on / off valve are controlled to open and close so that the real-time liquid level height of the refrigerant in the refrigerant regulating tank is adjusted to the target liquid level height h.

[0018] In some embodiments, when the real-time liquid level of the refrigerant in the refrigerant regulating tank is lower than the target liquid level h, the second solenoid on / off valve is controlled to open and the first solenoid on / off valve is controlled to close, until the real-time liquid level rises to the target liquid level h, at which point the second 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 first solenoid on / off valve is controlled to open and the second solenoid on / off valve is controlled to close, until the real-time liquid level drops to the target liquid level h, at which point the first 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] By controlling the opening and closing of the aforementioned second and third pipelines and utilizing the pressure difference between the top and bottom of the refrigerant regulating tank, the liquid refrigerant inside can be released (migrated out) or stored (migrated in). This allows the refrigerant stored in the refrigerant regulating tank to be migrated to replenish the system circulation, increasing the refrigerant charge in the system circulation. Alternatively, it allows excess refrigerant in the system circulation to be migrated and stored in the refrigerant regulating tank, effectively preventing excessive refrigerant charge in the system from causing liquid accumulation and preventing 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; 4. Oil separator; 41. Second capillary tube; 101. First pipeline; 1011. First capillary tube; 102. Second pipeline; 1021. First solenoid on / off valve; 103. Third pipeline; 1031. Second solenoid on / off valve; 104. Fourth pipeline; 1041. First check valve; 105. Fifth pipeline; 1051. 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 2As 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 which is connected to the outlet of the evaporator 11 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. The bottom of the refrigerant regulating tank 2 is also controllably connected to the inlet of the throttling element 13 or the outlet of the liquid storage tank 14 via a third pipe 103. It is understood that the top of the refrigerant regulating tank 2 is the top space inside the tank, which usually contains gaseous refrigerant. The top of the liquid storage tank 14 is the top space inside the tank, which usually contains gaseous refrigerant.

[0036] In this technical solution, by controlling the opening and closing of the aforementioned second pipeline 102 and third pipeline 103, the liquid refrigerant in the refrigerant regulating tank 2 is released (migrated out) or stored (migrated in) by utilizing the pressure difference between the top and bottom of the refrigerant regulating tank 2. This allows the refrigerant stored in the refrigerant regulating tank 2 to be migrated and replenished into the system circulation, increasing the refrigerant charge in the system circulation. Alternatively, it allows excess refrigerant in the system circulation to be migrated and stored in the refrigerant regulating tank 2, effectively preventing excessive refrigerant charge in the system from causing liquid accumulation and preventing excessive refrigerant from occupying the heat exchange pipes in the heat exchanger, thus improving heat exchange efficiency. In this way, the technical solution of this 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.

[0037] The bottom of the refrigerant regulating tank 2 is higher than the top 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.

[0038] In this technical solution, the refrigerant regulating tank 2 is positioned relatively high. When the second pipeline 102 is connected, the liquid refrigerant in the refrigerant regulating tank 2 can also enter the liquid storage tank 14, which is positioned relatively low, under its own weight. This increases the amount of refrigerant injected into the system circulation and further ensures that the refrigerant is smoothly released into the system circulation.

[0039] In some embodiments, a first electromagnetic on / off valve 1021 is connected in series on the second pipeline 102, and a second electromagnetic on / off valve 1031 is connected in series on the third pipeline 103. By setting corresponding electromagnetic on / off valves on the second pipeline 102 and the third pipeline 103 respectively, the pipeline is controlled to open and close. The control is simple and the implementation cost is low. In a preferred embodiment, the electromagnetic on / off valve is a normally closed valve when de-energized, that is, it opens to flow when energized and cuts off to stop flow when de-energized.

[0040] In a preferred embodiment, a first capillary tube 1011 is connected in series on the first pipeline 101. The structure is simple and the system construction cost is low, so that the refrigerant flowing in the first pipeline 101 can be throttled and depressurized or pressure obtained (controlling flow).

[0041] 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 fourth pipeline 104 is also connected between the inlet of the refrigerant pump 15 and the inlet of the throttling element 13. A first one-way valve 1041 is connected in series on the fourth pipeline 104. The one-way flow direction of the first one-way valve 1041 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 one-way valve 1041 will block the flow of refrigerant through the fourth pipeline 104 under the action of reverse pressure difference.

[0042] 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 fourth pipeline 104 connected in parallel with the fluorine pump 15. The structure is simple and easy to implement.

[0043] In some embodiments, the refrigerant pump compression refrigeration system further includes a compressor 16 and a fifth pipeline 105. 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 fifth pipeline 105 is connected between the suction port and the discharge port of the compressor 16, and a second one-way valve 1051 is connected in series on the fifth pipeline 105. The one-way flow direction of the second one-way valve 1051 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 1051 will stop the flow of refrigerant through the fifth pipeline 105 under the action of reverse pressure difference.

[0044] In some embodiments, an oil separator 4 is connected in series on the pipeline between the exhaust port of the compressor 16 and the condenser 12. The outlet of the oil return pipe of the oil separator 4 is connected to the intake port of the compressor 16 via a second capillary tube 41. In this technical solution, by setting the oil separator 4, the lubricating oil in the exhaust gas flow of the compressor 16 can be separated and then flowed back into the compressor 16, ensuring sufficient lubrication of the components inside the compressor 16. At the same time, it prevents the lubricating oil from accumulating in the heat exchanger in the system circulation, which would reduce the heat exchange efficiency and reduce the heat exchange effect.

[0045] 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.

[0046] Thus, by adding only two solenoid valves (i.e., the aforementioned first solenoid on / off valve 1021 and second solenoid on / off valve 1031), one regulating tank (i.e., the aforementioned refrigerant regulating tank 2), and a pressure-reducing capillary tube (i.e., the aforementioned first capillary tube 1011), redundant regulation of the refrigerant can be achieved. In compression refrigeration mode, the pressure difference is used to store excess refrigerant in the regulating tank, preventing excessive refrigerant in the refrigeration system from occupying the heat exchange pipes in the heat exchanger. In refrigerant pump refrigeration mode, gravity and pressure difference are used to migrate the refrigerant in the regulating tank to the liquid receiver, ensuring that there is sufficient refrigerant liquid level in the liquid receiver, preventing the refrigerant pump from cavitation due to excessively low pressure at the suction end.

[0047] It should be noted that when the third pipeline 103 is controllably connected to the inlet of the throttling element 13, please refer to the following for details. Figure 1 As shown, when the system is operating in compression refrigeration mode, if it is necessary to store refrigerant in the refrigerant regulating tank 2 (i.e., to transfer refrigerant into the regulating tank), the refrigerant pump 15 can be controlled to operate (at this time, the second solenoid on / off valve 1031 is open and the first solenoid on / off valve 1021 is closed), thereby more efficiently and smoothly lifting excess liquid refrigerant in the system circulation (i.e., the liquid refrigerant in the liquid receiver 14) into the refrigerant regulating tank 2; and when the third pipeline 103 is controllably connected to the liquid outlet of the liquid receiver 14, see... Figure 2 As shown, when the system is running in refrigerant pump refrigeration mode, the first solenoid on / off valve 1021 and the second solenoid on / off valve 1031 can be controlled to be turned on simultaneously. In this way, the liquid refrigerant in the refrigerant regulating tank 2 and the liquid storage tank 14 can be drawn into the refrigerant pump 15 under the action of the refrigerant pump 15. Of course, after the liquid refrigerant in the refrigerant regulating tank 2 is completely discharged, the first solenoid on / off valve 1021 and the second solenoid on / off valve 1031 should be controlled to be turned off.

[0048] 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:

[0049] Obtain the operating mode of the fluorine pump compression refrigeration system;

[0050] The operation mode controls the opening and closing of the first electromagnetic on / off valve 1021 and the second electromagnetic on / off valve 1031, as well as the start and stop of the compressor 16 and the fluorine pump 15.

[0051] Specifically, when the operating mode is the refrigerant pump refrigeration mode, the first solenoid on / off valve 1021 is turned on (at this time, the second solenoid on / off valve 1031 is turned off), the compressor 16 is controlled to stop running or remain in a stopped state, the liquid refrigerant in the refrigerant regulating tank 2 flows into the liquid storage tank 14 through the second pipeline 102 under its own weight, and the refrigerant pump 15 is controlled to run after the refrigerant in the refrigerant regulating tank 2 has completely flowed into the liquid storage tank 14.

[0052] That is, when the system is running in refrigerant pump refrigeration mode, before controlling the refrigerant pump 15 to operate, the first solenoid on / off valve 1021 is first opened, so that the liquid refrigerant in the refrigerant regulating tank 2 migrates back to the liquid receiver 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 receiver 14, preventing the refrigerant pump from cavitating due to excessively low pressure at the liquid inlet (i.e., liquid outlet) of the refrigerant pump 15. Before the refrigerant pump 15 starts operating, it is preferable to de-energize the first solenoid on / off valve 1021 to cut off the flow.

[0053] 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 first electromagnetic on / off valve 1021 and the second electromagnetic on / off valve 1031 are controlled to open and close 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.

[0054] 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.

[0055] Specifically, when the real-time liquid level of the refrigerant in the refrigerant regulating tank 2 is lower than the target liquid level h, it indicates that there is too much refrigerant circulating in the system. At this time, the second solenoid on / off valve 1031 is opened and the first solenoid on / off valve 1021 is shut off. Since the compressor 16 is running, some of the liquid refrigerant flowing out of the liquid storage tank 14 enters the refrigerant regulating tank 2 from the bottom due to the pressure difference between the liquid refrigerant and the outlet of the evaporator 11 (i.e., the suction pressure of the compressor 16). The gaseous refrigerant is further throttled through the first capillary tube 1011 in the first pipeline 101 and flows back to the compressor 16. During this process, the liquid refrigerant is migrated from the system circulation into the refrigerant regulating tank 2 and stored, thereby reducing the amount of refrigerant charged in the system circulation and effectively preventing the phenomenon of low heat exchange efficiency caused by the deposition of redundant refrigerant in the heat exchanger. This continues until the real-time liquid level rises to the target liquid level h, at which point the second solenoid on / off valve 1031 is shut off to prevent the system from... Excessive refrigerant charge participating in the circulation leads to liquid accumulation, thereby increasing heat exchange efficiency; or, 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 the amount of refrigerant participating in the circulation in the system is insufficient. At this time, the first electromagnetic on / off valve 1021 is opened and the second electromagnetic on / off valve 1031 is shut off. At this time, the refrigerant gas entering the liquid storage tank 14 will enter the refrigerant regulating tank 2 along the second pipeline 102. Due to the first capillary tube 10 in the first pipeline 101... Due to the throttling effect of 11, the gaseous refrigerant in the top area of ​​the refrigerant regulating tank 2 will increase and form a certain pressure. This pressure acts on the surface of the refrigerant liquid in the tank, so that the liquid refrigerant in the refrigerant regulating tank 2 flows into the liquid storage tank 14 through the second pipeline 102 under the action of its own weight and pressure difference (that is, it forms a counterflow with the gaseous refrigerant) until the real-time liquid level drops to the target liquid level height h, and then the first electromagnetic on / off valve 1021 is controlled to cut off, thereby increasing the amount of refrigerant charged in the system circulation.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] The following combination Figure 1 The technical solution of the present invention is further described as follows:

[0060] 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 check valve 1051 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 → oil separator → condenser (i.e., the aforementioned condenser 12, the same below) → liquid receiver (i.e., the aforementioned liquid receiver 14, the same below) → first check valve 1041 → throttle valve (i.e., the aforementioned throttle element 13, the same below) → evaporator (i.e., the aforementioned evaporator 11, the same below) → compressor.

[0061] 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. This involves closing the first solenoid valve 1021 and opening the second solenoid valve 1031. A pressure difference exists between the high-pressure refrigerant liquid at the receiver tank outlet and the low-pressure gas at the compressor suction port, causing some high-pressure refrigerant liquid to flow into the regulating tank from the second solenoid valve 1031. When the liquid level in the regulating tank reaches height h (i.e., the aforementioned target liquid level height h, hereinafter the same), the second solenoid valve 1031 is closed to complete the compression refrigeration process. Refrigerant regulation and control: When the compressor frequency increases, the required system circulation volume usually increases, requiring some refrigerant in the regulating tank to be transferred out to participate in the system circulation: the first solenoid on / off valve 1021 is opened and the second solenoid on / off valve 1031 is closed. The refrigerant liquid in the regulating tank flows into the gas area at the top of the liquid receiver tank under the action of gravity through the first solenoid on / off valve 1021 and mixes with the refrigerant liquid in the liquid receiver tank. When the liquid level height h in the regulating tank drops to the corresponding high frequency of the compressor, the first solenoid on / off valve 1021 is closed to complete the refrigerant migration control.

[0062] B) Refrigerant pump refrigeration mode - The refrigerant pump is on and the compressor is off because the first check valve 1041 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 check valve 1051 → oil separator → condenser → liquid receiver → refrigerant pump.

[0063] Because the refrigerant pump mode requires the largest amount of refrigerant (as explained in the background art, the main reason is to increase the liquid level in the receiver tank, ensure the safety of the refrigerant pump's suction, and avoid cavitation), all the refrigerant liquid in the regulating tank needs to be transferred into the system to participate in the circulation. At this time, the first solenoid on / off valve 1021 is opened and the second solenoid on / off valve 1031 is closed. The refrigerant gas pressure at the evaporator outlet is greater than the refrigerant pressure in the receiver tank. Therefore, there is a reverse pressure difference at capillary tube B. As a result, the refrigerant liquid in the regulating tank enters the receiver tank under the action of gravity and the refrigerant pressure difference. When the level gauge and / or level sensor detect that the liquid level height h in the regulating tank is 0, the first solenoid on / off valve 1021 is closed to complete the migration control of the refrigerant liquid in the regulating tank.

[0064] 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.

[0065] 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 evaporator (11) via a first pipe (101), the bottom of which is connected to the top of the liquid storage tank (14) via a second pipe (102), and the bottom of which is connected to the inlet of the throttling element (13) or the outlet of the liquid storage tank (14) via a third pipe (103).

2. The fluorine pump compression refrigeration system according to claim 1, characterized in that, A first electromagnetic on / off valve (1021) is connected in series on the second pipeline (102), and a second electromagnetic on / off valve (1031) is connected in series on the third pipeline (103); and / or, a first capillary tube (1011) is connected in series on the first pipeline (101); 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 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 fourth pipeline (104) is connected between the inlet of the fluorine pump (15) and the inlet of the throttling element (13). A first check valve (1041) is connected in series on the fourth pipeline (104), and the unidirectional flow direction of the first check valve (1041) is from the inlet side of the fluorine pump (15) to the inlet side of the throttling element (13).

4. The fluorine pump compression refrigeration system according to claim 3, characterized in that, It also includes a compressor (16) and a fifth pipeline (105). 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 fifth pipeline (105) is connected between the suction port and the discharge port of the compressor (16), and a second one-way valve (1051) is connected in series on the fifth pipeline (105). The one-way conduction direction of the second one-way valve (1051) is from the suction port side of the compressor (16) to the discharge port side of the compressor (16).

5. The fluorine pump compression refrigeration system according to claim 4, characterized in that, An oil separator (4) is connected in series on the pipeline between the exhaust port of the compressor (16) and the condenser (12). The outlet of the oil return pipe of the oil separator (4) is connected to the suction port of the compressor (16) via a second capillary tube (41).

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 4, characterized in that, Includes the following steps: Obtain the operating mode of the fluorine pump compression refrigeration system; The operation mode controls the opening and closing of the first electromagnetic on / off valve (1021) and the second electromagnetic on / off valve (1031), as well as 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 first electromagnetic on / off valve (1021) is turned on, the compressor (16) is turned off or kept in a stopped 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 first electromagnetic on / off valve (1021) and the second electromagnetic on / off valve (1031) are controlled to open and close 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 second electromagnetic on / off valve (1031) is turned on and the first electromagnetic on / off valve (1021) is turned off, until the real-time liquid level rises to the target liquid level h, at which point the second electromagnetic on / off valve (1031) is turned off; 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 first electromagnetic on / off valve (1021) is controlled to open and the second electromagnetic on / off valve (1031) is controlled to close, until the real-time liquid level drops to the target liquid level h, and then the first 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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