Fluorine pump compression refrigeration system and control method thereof

Abstract

The invention provides a fluorine pump compression refrigerating system and a control method thereof.The system comprises an evaporator, a condenser and a throttling element, the throttling element is connected between an outlet of the condenser and an inlet of the evaporator, a liquid storage tank is connected between the condenser and the throttling element, and the fluorine pump compression refrigerating system further comprises a refrigerant adjusting tank; the top of the refrigerant adjusting tank communicates with an outlet of the evaporator through a first pipeline, the bottom of the refrigerant adjusting tank communicates with the top of the liquid storage tank through a second pipeline in a controllable on-off mode, and the bottom of the refrigerant adjusting tank further communicates with a liquid inlet of the throttling element through a third pipeline in a controllable on-off mode or communicates with a liquid outlet of the liquid storage tank in a controllable on-off mode. Refrigerant migration is achieved by controlling connection and disconnection of the second pipeline and the third pipeline, accumulated liquid retention in the system caused by too large refrigerant filling amount in the system is effectively prevented, excessive refrigerant in the refrigerating system is prevented from occupying a heat exchange pipeline in the heat exchanger, and the heat exchange efficiency is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of air conditioning, and in particular relates to a fluorine pump compression refrigeration system and a control method thereof. Background Art

[0002] With the extensive application of 4G and the gradual popularization of 5G, the heat generated by various data processing equipment is getting higher and higher, and data centers have higher and higher requirements for the cooling capacity and energy saving of air-conditioning equipment.

[0003] Using outdoor natural cold sources in transitional seasons and cold winters to cool the data center can significantly reduce the operating costs of air conditioning equipment. A common method is to use fluorine pump air conditioning, enable the fluorine pump mode in winter, stop the operation of the compressor, and use the fluorine pump to drive the refrigerant to achieve heat pipe refrigeration operation, which greatly reduces the operating costs of the equipment. The fluorine pump compression refrigeration system is a composite system. The fluorine pump heat pipe system and the compression refrigeration system share the evaporator and condenser, as well as some common refrigerant pipelines, system components, etc.

[0004] Since the heat load of the data center fluctuates with user usage and seasonal changes, more and more computer room air conditioners now use variable frequency technology to cope with the heat load fluctuations of the data center and ensure the constant temperature and humidity requirements of the data center. However, the change in the compressor frequency of the refrigeration system will cause the optimal refrigerant circulation volume to change. Generally, the higher the frequency, the greater the refrigerant circulation volume required. If the optimal refrigerant injection volume at 100% load is guaranteed during the design and development of the refrigeration system, the optimal refrigerant injection volume at 75% or 50% load or other low-frequency operation conditions will be relatively small. Therefore, the refrigerant inside the unit may accumulate liquid under low-frequency conditions, and the accumulated liquid is retained at the bottom of the heat exchanger, which is not conducive to heat exchange.

[0005] At the same time, in the fluorine pump mode, considering the liquid height requirement at the suction port of the fluorine pump, the required refrigerant filling amount is usually large in the fluorine pump mode. Therefore, the fluorine pump compression refrigeration system is likely to form refrigerant liquid retention under actual operating conditions. It is necessary to consider migrating the retained refrigerant to the liquid storage tank, and in the high-frequency compression refrigeration mode or the fluorine pump refrigeration mode, the refrigerant liquid retained in the liquid storage tank should be released as soon as possible to participate in the system circulation operation. Summary of the invention

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

[0007] In order to solve the above problems, the present invention provides a fluorine pump compression refrigeration system, comprising an evaporator, a condenser and a throttling element, wherein the throttling element is connected between the outlet of the condenser and the inlet of the evaporator, and a liquid storage tank is connected between the condenser and the throttling element. The fluorine pump compression refrigeration system also includes a refrigerant regulating tank, the top of the refrigerant regulating tank is connected to the outlet of the evaporator through a first pipeline, the bottom of the refrigerant regulating tank is controllably connected to the top of the liquid storage tank through a second pipeline, and the bottom of the refrigerant regulating tank is also controllably connected to the liquid inlet of the throttling element or the liquid outlet of the liquid storage tank through a third pipeline.

[0008] In some embodiments, a first electromagnetic on-off valve is connected in series to the second pipeline, and a second electromagnetic on-off valve is connected in series to the third pipeline; and / or a first capillary tube is connected in series to 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 the action of its own weight.

[0009] In some embodiments, the fluorine pump compression refrigeration system also includes a fluorine pump, the liquid inlet of the fluorine pump is connected to the bottom of the liquid storage tank, the liquid outlet of the fluorine pump is connected to the liquid inlet of the throttling element, and a fourth pipeline is also connected between the liquid inlet of the fluorine pump and the liquid inlet of the throttling element, and a first one-way valve is connected in series on the fourth pipeline, and the one-way conduction direction of the first one-way valve is from the liquid inlet side of the fluorine pump to the liquid inlet side of the throttling element.

[0010] In some embodiments, the fluorine pump compression refrigeration system also includes a compressor and a fifth pipeline, the air intake of the compressor is connected to the air outlet of the evaporator, the air exhaust of the compressor is connected to the air inlet of the condenser, the fifth pipeline is connected between the air intake and exhaust ports of the compressor, and a second one-way valve is connected in series on the fifth pipeline, and the one-way conduction direction of the second one-way valve is from the air intake side of the compressor to the air exhaust side of the compressor.

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

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

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

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

[0015] The on and off of the first electromagnetic on and off valve and the second electromagnetic on and off valve, and the start and stop of the compressor and the fluorine pump are controlled according to the operation mode.

[0016] In some embodiments, when the operating mode is the fluorine pump refrigeration mode, the first electromagnetic on-off valve is controlled to be turned on, the compressor is controlled to stop running or remain in a stopped state, and the fluorine pump is controlled to operate after the refrigerant in the refrigerant regulating tank completely flows into the liquid storage tank.

[0017] In some embodiments, when the operating mode is a compression refrigeration mode, the compressor is controlled to operate and the real-time operating frequency of the compressor is obtained, and the target liquid level height h of the refrigerant in the refrigerant regulating tank corresponding to the real-time operating frequency is obtained according to the obtained real-time operating frequency, and the first electromagnetic on-off valve and the second electromagnetic on-off valve are controlled to be on and off 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 electromagnetic on-off valve is controlled to be turned on and the first electromagnetic on-off valve is turned off, until the real-time liquid level rises to the target liquid level h, the second electromagnetic on-off valve is controlled to be turned off; 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 electromagnetic on-off valve is controlled to be connected and the second electromagnetic on-off valve is controlled to be cut off, until the real-time liquid level drops to the target liquid level h, and the first electromagnetic on-off valve is controlled to be cut off.

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

[0021] Obtaining the optimal refrigerant filling amount m1 of the system cycle corresponding to the real-time operating frequency, and calculating the refrigerant amount m2 to be stored in the refrigerant regulating tank, m2=m-m1, where m is the total refrigerant amount in the system;

[0022] Acquire the real-time temperature t and / or the real-time saturation pressure in the refrigerant regulating tank, and acquire the liquid refrigerant density ρ corresponding to the real-time temperature t and / or the real-time saturation pressure according to the refrigerant parameters pre-stored in the controller;

[0023] 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.

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

[0025] By controlling the on-off of the aforementioned second pipeline and the third pipeline and utilizing the pressure difference between the top and the bottom of the refrigerant regulating tank to realize the release (migration) or storage (migration) of the liquid refrigerant therein, the refrigerant stored in the refrigerant regulating tank is migrated and supplemented to the system circulation, thereby increasing the refrigerant filling amount of the system circulation, or the excess refrigerant in the system circulation is migrated and stored in the refrigerant regulating tank, thereby effectively preventing the system from being filled with too much refrigerant and causing liquid accumulation in the system, preventing the existence of excessive refrigerant in the refrigeration system from occupying the heat exchange pipes in the heat exchanger, and improving the heat exchange efficiency; in this way, the technical solution of the present invention realizes the controllable adjustment of the refrigerant circulation amount required in the refrigeration system, meets the requirements of the optimal system circulation amount, and solves the refrigerant redundancy problem caused by the difference in the refrigerant filling amount required under different operating conditions of the fluorine pump compression refrigeration system in the prior art, so as to meet the optimal circulation amount required by the refrigeration system under various operating conditions as much as possible. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the implementation methods of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the implementation methods or the description of the prior art. The drawings described below are only exemplary, and for ordinary technicians in this field, other implementation drawings can be derived from the provided drawings without creative work.

[0027] Figure 1 2 is a schematic diagram of the principle of a fluorine pump compression refrigeration system according to an embodiment of the present invention;

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

[0029] The accompanying drawings are marked as follows:

[0030] 11. Evaporator; 111. Inner fan; 12. Condenser; 121. Outer fan; 13. Throttling element; 14. Liquid storage tank; 15. Fluorine pump; 16. Compressor; 2. Refrigerant regulating tank; 21. Liquid level gauge; 4. Oil separator; 41. Second capillary tube; 101. First pipeline; 1011. First capillary tube; 102. Second pipeline; 1021. First electromagnetic on-off valve; 103. Third pipeline; 1031. Second electromagnetic on-off valve; 104. Fourth pipeline; 1041. First non-return valve; 105. Fifth pipeline; 1051. Second non-return valve. DETAILED DESCRIPTION

[0031] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is by no means intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0032] In the description of the present invention, it is necessary to understand that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "lateral, vertical, perpendicular, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention. The directional words "inside and outside" refer to the inside and outside relative to the contours of each component itself.

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

[0034] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. If not otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0035] See also Figure 1 and Figure 2As shown, according to an embodiment of the present invention, a fluorine pump compression refrigeration system is provided, comprising an evaporator 11, a condenser 12 and a throttling element 13 (e.g., an electronic expansion valve), wherein 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 fluorine pump compression refrigeration system also comprises a refrigerant regulating tank 2, the top of the refrigerant regulating tank 2 is connected to the outlet of the evaporator 11 through a first pipeline 101, and the refrigeration The bottom of the refrigerant regulating tank 2 is controllably connected to the top of the liquid storage tank 14 via the second pipeline 102, and the bottom of the refrigerant regulating tank 2 is also controllably connected to the liquid inlet of the throttling element 13 or the liquid outlet of the liquid storage tank 14 via the third pipeline 103. It can be understood that the top of the refrigerant regulating tank 2 is the top space in the tank, and generally speaking, the top space contains gaseous refrigerant, and the top of the liquid storage tank 14 is the top space in the tank, and generally speaking, the top space contains gaseous refrigerant.

[0036] In this technical solution, by controlling the on-off of the aforementioned second pipeline 102 and the third pipeline 103 and then utilizing the pressure difference between the top and the bottom of the refrigerant regulating tank 2 to realize the release (migration) or storage (migration) of the liquid refrigerant therein, the refrigerant stored in the refrigerant regulating tank 2 is migrated and supplemented to the system circulation, thereby increasing the refrigerant filling amount of the system circulation, or the excessive refrigerant in the system circulation is migrated and stored in the refrigerant regulating tank 2, thereby effectively preventing the excessive refrigerant filling amount in the system from causing liquid accumulation in the system, preventing the existence of excessive refrigerant in the refrigeration system from occupying the heat exchange pipes in the heat exchanger, and improving the heat exchange efficiency; in this way, the technical solution of the present invention realizes the controllable adjustment of the refrigerant circulation amount required in the refrigeration system, meets the requirements of the optimal system circulation amount, and solves the refrigerant redundancy problem caused by the difference in the refrigerant filling amount required under different operating conditions of the fluorine pump compression refrigeration system in the prior art, so as to meet the optimal circulation amount required by the refrigeration system under various operating conditions as much as possible.

[0037] 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 the action of its own weight.

[0038] In this technical solution, the refrigerant regulating tank 2 is set at a higher position. When the second pipeline 102 is controlled to be connected, the liquid refrigerant in the refrigerant regulating tank 2 can also enter the liquid storage tank 14 set at a lower position under the action of its own weight, thereby increasing the refrigerant filling amount in the system cycle, and further ensuring that the refrigerant is smoothly released in the system cycle.

[0039] In some embodiments, a first electromagnetic on-off valve 1021 is connected in series to the second pipeline 102, and a second electromagnetic on-off valve 1031 is connected in series to the third pipeline 103. By respectively providing corresponding electromagnetic on-off valves on the second pipeline 102 and the third pipeline 103, the on-off control of the pipelines is simple and the implementation cost is low. In a preferred embodiment, the electromagnetic on-off valve is a normally closed valve when the power is on, that is, it is open for flow when the power is on, and it is cut off when the power is off.

[0040] In a preferred embodiment, a first capillary tube 1011 is serially connected to the first pipeline 101, which has a simple structure and a low system construction cost, so as to be able to throttle and reduce the pressure or obtain the pressure (control the flow) of the refrigerant flowing in the first pipeline 101.

[0041] In some embodiments, the fluorine pump compression refrigeration system also includes a fluorine pump 15, the liquid inlet of the fluorine pump 15 is connected to the bottom of the liquid storage tank 14, the liquid outlet of the fluorine pump 15 is connected to the liquid inlet of the throttling element 13, and a fourth pipeline 104 is also connected between the liquid inlet of the fluorine pump 15 and the liquid inlet of the throttling element 13, and a first one-way valve 1041 is connected in series to the fourth pipeline 104, and the one-way conduction direction of the first one-way valve 1041 is from the liquid inlet side of the fluorine pump 15 to the liquid inlet side of the throttling element 13. It can be understood that when the fluorine pump 15 is running, the first one-way valve 1041 will cut off the circulation of the refrigerant through the fourth pipeline 104 under the action of the reverse pressure difference.

[0042] In this technical solution, the fourth pipeline 104 connected in parallel with the fluorine pump 15 can realize the automatic switching between the compression refrigeration mode and the fluorine pump refrigeration mode of the fluorine pump compression refrigeration system of the present invention, and the structure is simple and easy to operate.

[0043] In some embodiments, the fluorine pump compression refrigeration system further includes a compressor 16 and a fifth pipeline 105, the air intake of the compressor 16 is communicated with the air outlet of the evaporator 11, the air outlet of the compressor 16 is communicated with the air inlet of the condenser 12, the fifth pipeline 105 is connected between the air intake and the air outlet of the compressor 16, and a second one-way valve 1051 is serially connected to the fifth pipeline 105, and the one-way conduction direction of the second one-way valve 1051 is from the air intake side of the compressor 16 to the air outlet side of the compressor 16. When the compressor 16 is running, the second one-way valve 1051 will cut off the circulation of the refrigerant of the fifth pipeline 105 under the action of the reverse pressure difference.

[0044] In some embodiments, an oil separator 4 is further connected in series to the pipeline between the exhaust port of the compressor 16 and the condenser 12, and the outlet of the oil return pipe of the oil separator 4 is connected to the air intake port of the compressor 16 via a second capillary tube 41. In this technical solution, the lubricating oil in the exhaust gas flow of the compressor 16 can be separated by setting the oil separator 4 and then refluxed into the compressor 16, thereby ensuring sufficient lubrication of various components in the compressor 16, and preventing the lubricating oil from being retained in the heat exchanger in the system circulation, resulting in reduced heat exchange efficiency and reduced heat exchange effect.

[0045] In some embodiments, a liquid level meter 21 is provided in the refrigerant regulating tank 2 for detecting the real-time liquid level height of the refrigerant in the refrigerant regulating tank 2; and / or, a temperature sensor (not shown in the figure) is provided in the refrigerant regulating tank 2 for detecting the real-time temperature of the refrigerant in the refrigerant regulating tank 2.

[0046] In this way, only two solenoid valves (i.e., the aforementioned first solenoid on-off valve 1021 and the second solenoid on-off valve 1031), one regulating tank (i.e., the aforementioned refrigerant regulating tank 2) and a pressure-reducing capillary (i.e., the aforementioned first capillary 1011) need to be added to achieve redundant regulation of the refrigerant. In the compression refrigeration mode, the pressure difference is used to store excess refrigerant in the regulating tank to prevent excessive refrigerant in the refrigeration system from occupying the heat exchange pipes in the heat exchanger; in the fluorine pump refrigeration mode, gravity and pressure difference are used to migrate the refrigerant in the regulating tank to the liquid storage tank to ensure that there is sufficient refrigerant liquid height in the liquid storage tank to prevent the fluorine pump cavitation caused by excessive low pressure at the suction end of the fluorine pump.

[0047] It should be noted that when the third pipeline 103 is controllably connected to the liquid inlet of the throttling element 13, see Figure 1 As shown, when the system operates in compression refrigeration mode, when it is necessary to store refrigerant in the refrigerant regulating tank 2 (i.e., to transfer refrigerant into the regulating tank), the fluorine pump 15 can be controlled to operate (at this time, the second electromagnetic on-off valve 1031 is turned on and the first electromagnetic on-off valve 1021 is turned off), so that the excess liquid refrigerant in the system cycle (i.e., the liquid refrigerant in the liquid storage tank 14) can be lifted and input into the refrigerant regulating tank 2 more efficiently and smoothly; and when the third pipeline 103 is controllably connected to the liquid outlet of the liquid storage tank 14, see Figure 2 As shown, when the system operates in the fluorine pump refrigeration mode, the first electromagnetic on-off valve 1021 and the second electromagnetic on-off valve 1031 can be controlled to be turned on at the same time. In this way, the liquid refrigerant in the refrigerant regulating tank 2 and the liquid storage tank 14 can be sucked into the fluorine pump 15 under the action of the fluorine pump 15. Of course, after the liquid refrigerant in the refrigerant regulating tank 2 is completely discharged, the first electromagnetic on-off valve 1021 and the second electromagnetic on-off valve 1031 should be controlled to be cut off.

[0048] According to an embodiment of the present invention, there is also provided a control method for the fluorine pump compression refrigeration system as described above, comprising the following steps:

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

[0050] The on / off of the first electromagnetic on / off valve 1021 and the second electromagnetic on / off valve 1031 , and the start / stop of the compressor 16 and the fluorine pump 15 are controlled according to the operation mode.

[0051] Specifically, when the operating mode is the fluorine pump refrigeration mode, the first electromagnetic on-off valve 1021 is controlled to be turned on (the second electromagnetic on-off valve 1031 is cut off at this time), the compressor 16 is controlled to stop running or remain in a stopped state, and 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 the fluorine pump 15 is controlled to operate after the refrigerant in the refrigerant regulating tank 2 completely flows into the liquid storage tank 14.

[0052] That is, when the system is running the fluorine pump refrigeration mode, before controlling the fluorine pump 15 to operate, the first electromagnetic on-off valve 1021 is first controlled to be turned on, so that the liquid refrigerant in the refrigerant regulating tank 2 is completely transferred back to the liquid storage tank 14 under the action of its own weight, and then the fluorine pump 15 is controlled to operate the fluorine pump refrigeration mode, so as to ensure that there is enough refrigerant liquid height in the liquid storage tank 14, and prevent the pressure at the suction end (i.e., the liquid inlet) of the fluorine pump 15 from being too low to cause fluorine pump cavitation. Before the fluorine pump 15 is operated, it is preferred that the first electromagnetic on-off valve 1021 is powered off to cut off the flow.

[0053] In some embodiments, when the operating mode is a compression refrigeration mode, the compressor 16 is controlled to operate and the real-time operating frequency of the compressor 16 is obtained, and the target liquid level height h of the refrigerant in the refrigerant regulating tank 2 corresponding to the real-time operating frequency is obtained according to the obtained real-time operating frequency, and the first electromagnetic on-off valve 1021 and the second electromagnetic on-off valve 1031 are controlled to be on and off 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 operates 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 filling amount in the system matches each real-time operating frequency, that is, they are all at the optimal filling amount, meeting the better system circulation volume requirements.

[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 electromagnetic on-off valve 1031 is controlled to be turned on and the first electromagnetic on-off valve 1021 is turned off. At this time, since the compressor 16 is in operation, the liquid refrigerant flowing out of the liquid storage tank 14 partially enters the refrigerant regulating tank 2 from the bottom of the refrigerant regulating tank 2 under the action of the pressure difference between the liquid storage tank 14 and the outlet of the evaporator 11 (that is, the suction pressure of the compressor 16), and the gaseous refrigerant further flows back to the compressor 16 after throttling through the first capillary 1011 in the first pipeline 101. In this process, the liquid refrigerant is migrated from the system circulation into the refrigerant regulating tank 2 and stored, thereby reducing the refrigerant filling amount in the system circulation, effectively preventing the occurrence of low heat exchange efficiency caused by the deposition of redundant refrigerant in the heat exchanger, until the real-time liquid level rises to the target liquid level h, the second electromagnetic on-off valve 1031 is controlled to be turned off to prevent the system When the amount of refrigerant circulating in the refrigerant regulating tank 2 is too large, liquid accumulation occurs, thereby improving the 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 refrigerant circulating in the system is too little. At this time, the first electromagnetic on-off valve 1021 is controlled to be connected and the second electromagnetic on-off valve 1031 is controlled to be cut 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 101 in the first pipeline 101, the refrigerant gas in the liquid storage tank 14 will enter the refrigerant regulating tank 2 along the second pipeline 102. 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, which acts on the refrigerant liquid surface 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 countercurrent with the gaseous refrigerant), until the real-time liquid level height drops to the target liquid level height h, and the first electromagnetic on-off valve 1021 is controlled to be cut off, thereby increasing the refrigerant filling amount of the system circulation.

[0056] In this way, dynamic adjustment of the refrigerant in the system under the compression refrigeration mode is achieved, which can ensure that the refrigerant injection amount in the system meets the optimal system circulation volume requirements.

[0057] In some embodiments, the target liquid level height h is obtained by: obtaining the optimal refrigerant filling amount m1 of the system cycle corresponding to the real-time operating frequency (specifically pre-stored in the controller), and calculating the refrigerant amount m2 to be stored in the refrigerant regulating tank 2, m2=m-m1, where m is the total refrigerant amount in the system; obtaining the real-time temperature t and / or real-time saturation pressure in the refrigerant regulating tank 2, and obtaining the liquid refrigerant density ρ corresponding to the real-time temperature t and / or real-time saturation pressure according to the refrigerant parameters pre-stored in the controller; calculating the target liquid level height h according to the formula h=m2 / (ρS), where S is the cross-sectional area of ​​the storage space of the refrigerant regulating tank 2, and the aforementioned physical parameters can all be expressed in international units. In a specific embodiment, the refrigerant regulating tank 2 is a cylinder with equal upper and lower diameters, that is, each cross-sectional area S is equal, which can further simplify the acquisition of h.

[0058] In this technical solution, the optimal refrigerant filling amount m1 corresponding to the real-time operating frequency pre-stored in the controller is obtained to reversely infer the refrigerant amount m2 that should be stored in the refrigerant regulating tank 2, and then the corresponding target liquid level height is calculated through relevant physical parameters, which is simple and reliable.

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

[0060] A) Compression refrigeration mode - the fluorine pump (i.e. the aforementioned fluorine pump 15, hereinafter the same) is turned off, and the compressor (i.e. the aforementioned compressor 16, hereinafter the same) is turned on, because the second one-way valve 1051 cannot be conducted due to the reverse pressure difference at both ends at this time; the main circulation flow path of the refrigerant is: compressor → oil separator → condenser (i.e. the aforementioned condenser 12, hereinafter the same) → liquid storage tank (i.e. the aforementioned liquid storage tank 14, hereinafter the same) → first one-way valve 1041 → throttle valve (i.e. the aforementioned throttling element 13, hereinafter the same) → evaporator (i.e. the aforementioned evaporator 11, hereinafter the same) → compressor.

[0061] In the compression refrigeration mode, when the compressor frequency is reduced, the required system circulation volume is usually reduced, and some of the excess refrigerant needs to be transferred to the regulating tank: close the first electromagnetic on-off valve 1021 and open the second electromagnetic on-off valve 1031. There is a pressure difference between the high-pressure refrigerant liquid at the outlet of the storage tank and the low-pressure gas at the suction port of the compressor, causing part of the high-pressure refrigerant liquid to flow into the regulating tank from the second electromagnetic on-off valve 1031. When the liquid level in the regulating tank reaches the height h (that is, the aforementioned target liquid level height h, the same below), close the second electromagnetic on-off valve 1031 to complete the system. Regulation and control of refrigerant; when the frequency of the compressor increases, the required system circulation volume usually increases, and part of the refrigerant in the regulating tank needs to be migrated out to participate in the circulation of the system: open the first electromagnetic on-off valve 1021 and close the second electromagnetic on-off valve 1031. The refrigerant liquid in the regulating tank flows into the gas area at the top of the liquid storage tank through the first electromagnetic on-off valve 1021 under the action of gravity and mixes with the refrigerant liquid in the liquid storage tank. When the liquid level height h in the regulating tank drops to the corresponding high frequency of the compressor, the first electromagnetic on-off valve 1021 is closed to complete the migration control of the refrigerant.

[0062] B) Fluorine pump refrigeration mode - the fluorine pump is turned on and the compressor is turned off, because there is a reverse pressure difference at both ends of the first one-way valve 1041 and it cannot be connected; the main circulation flow path of the refrigerant is: fluorine pump → throttle valve → evaporator → second one-way valve 1051 → oil separator → condenser → liquid storage tank → fluorine pump.

[0063] Since the fluorine pump mode requires the largest amount of refrigerant filling (as explained in the background technology, the main reason is to increase the liquid level height in the liquid storage tank, ensure the safety of the fluorine pump's liquid suction and avoid cavitation of the fluorine pump), it is necessary to migrate all the refrigerant liquid in the regulating tank to the system to participate in the circulation. At this time, the first electromagnetic on-off valve 1021 is opened and the second electromagnetic on-off valve 1031 is closed. The refrigerant gas pressure at the evaporator outlet is greater than the refrigerant pressure in the liquid storage tank. Therefore, there is a reverse pressure difference at the capillary B. Therefore, the refrigerant liquid in the regulating tank enters the liquid storage tank under the action of gravity and the refrigerant pressure difference. When the liquid level meter and / or liquid level sensor detects that the liquid level height h in the regulating tank is 0, the first electromagnetic on-off valve 1021 is closed to complete the migration control of the refrigerant liquid in the regulating tank.

[0064] It is easy for those skilled in the art to understand that, without conflict, the advantageous technical features of the above-mentioned methods can be freely combined and superimposed.

[0065] The above description is only 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 principle of the present invention shall be included in the protection scope of the present invention. The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and variations can be made without departing from the technical principles of the present invention. These improvements and variations should also be regarded as 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 comprises a refrigerant regulating tank (2), the top of the refrigerant regulating tank (2) being connected to the outlet of the evaporator (11) via a first pipeline (101), the bottom of the refrigerant regulating tank (2) being controllably connected to the top of the liquid storage tank (14) via a second pipeline (102), and the bottom of the refrigerant regulating tank (2) being controllably connected to the liquid inlet of the throttling element (13) or the liquid outlet of the liquid storage tank (14) via a third pipeline (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 to the second pipeline (102), and a second electromagnetic on-off valve (1031) is connected in series to the third pipeline (103); and / or a first capillary tube (1011) is connected in series to 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 the action of 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 liquid inlet of the fluorine pump (15) is connected to the bottom of the liquid storage tank (14), the liquid outlet of the fluorine pump (15) is connected to the liquid inlet of the throttling element (13), and a fourth pipeline (104) is connected between the liquid inlet of the fluorine pump (15) and the liquid inlet of the throttling element (13), and a first one-way valve (1041) is connected in series to the fourth pipeline (104), and the one-way conduction direction of the first one-way valve (1041) is from the liquid inlet side of the fluorine pump (15) to the liquid 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), wherein the air intake port of the compressor (16) is connected to the air outlet port of the evaporator (11), and the air exhaust port of the compressor (16) is connected to the air inlet port of the condenser (12); the fifth pipeline (105) is connected between the air intake port and the air exhaust port of the compressor (16), and a second one-way valve (1051) is connected in series to the fifth pipeline (105); the one-way conduction direction of the second one-way valve (1051) is from the air intake port side of the compressor (16) to the air exhaust 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 also 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 air intake 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 provided with a liquid level meter (21) for detecting the real-time liquid level height of the refrigerant in the refrigerant regulating tank (2); and / or the refrigerant regulating tank (2) is provided 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 claimed in claim 4, characterized in that: The steps include: Obtaining the operating mode of the fluorine pump compression refrigeration system; The on / off of the first electromagnetic on / off valve (1021) and the second electromagnetic on / off valve (1031), and the start / stop of the compressor (16) and the fluorine pump (15) are controlled according to the operation mode.

8. The control method according to claim 7, characterized in that: When the operation mode is the fluorine pump refrigeration mode, the first electromagnetic on-off valve (1021) is controlled to be turned on, the compressor (16) is controlled to stop running or remain in a stopped state, and the fluorine pump (15) is controlled to operate after the refrigerant in the refrigerant regulating tank (2) completely flows into the liquid storage tank (14).

9. The control method according to claim 7, characterized in that: When the operation mode is the compression refrigeration mode, the compressor (16) is controlled to operate and the real-time operation frequency of the compressor (16) is obtained. The target liquid level height h of the refrigerant in the refrigerant regulating tank (2) corresponding to the real-time operation frequency is obtained based on the obtained real-time operation frequency. The first electromagnetic on-off valve (1021) and the second electromagnetic on-off valve (1031) are controlled to be on and off 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 controlled to be turned on and the first electromagnetic on-off valve (1021) is controlled to be turned off, until the real-time liquid level rises to the target liquid level h, and the second electromagnetic on-off valve (1031) is controlled to be 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 be connected and the second electromagnetic on-off valve (1031) is controlled to be cut off, until the real-time liquid level drops to the target liquid level h, and the first electromagnetic on-off valve (1021) is controlled to be cut off.

11. The control method according to claim 9, characterized in that: The target liquid level height h is obtained by: Obtaining the optimal refrigerant filling amount m1 of the system cycle corresponding to the real-time operating frequency, and calculating 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; Acquiring the real-time temperature t and / or the real-time saturation pressure in the refrigerant regulating tank (2), and obtaining the liquid refrigerant density ρ corresponding to the real-time temperature t and / or the real-time saturation pressure 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), wherein S is the cross-sectional area of ​​the storage space of the refrigerant regulating tank (2).

Images