A fluorine pump compression dual-cycle refrigeration unit and control method

Abstract

This invention provides a refrigerant pump-compressed dual-cycle refrigeration unit and its control method, comprising: a compressor, a refrigerant pump, a liquid receiver, and an oil return assembly. The oil return assembly can recover an oil-containing mixture from the liquid receiver and transport it to the compressor when the compressor and / or the refrigerant pump stops. The oil return assembly includes a floating body disposed inside the liquid receiver and capable of floating in the liquid within the receiver, rising or falling with the liquid level. The floating body is provided with a suction port to draw in the oil-containing mixture at the liquid surface. When the compressor and / or the refrigerant pump stops, and the temperature of the liquid receiver is below a preset temperature, the oil can be automatically discharged from the receiver using the stratification of the oil. This invention solves the problem of the inability to return oil to the compressor when the refrigerant pump-compressed dual-cycle refrigeration unit stops, preventing oil shortage in the compressor.

Description

Technical Field

[0001] This invention relates to the field of refrigeration technology, specifically to a refrigerant pump compression dual-cycle refrigeration unit 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, which activates the refrigerant pump mode in winter, stops the compressor from running, and uses the refrigerant pump to drive the refrigerant to achieve heat pipe cooling, greatly reducing the operating costs of the equipment.

[0004] Split-type air conditioning units typically use mechanically driven, separate heat pipes, such as those driven by a refrigerant pump (e.g., a liquid pump or a gas pump). When the heat pipe and heat pump share a system, a parallel design of a throttling element and a solenoid valve is usually employed. When the heat pump is running, the solenoid valve is closed, and the refrigerant operates by reducing its pressure through the throttling element. When the heat pipe is running, the solenoid valve is open, and the refrigerant primarily passes through the low-resistance solenoid valve to prevent the high resistance of the throttling element from consuming most of the gravity or the refrigerant pump's head.

[0005] While combining heat pipes and heat pumps in a system can reduce the number of components, system debugging and optimization are complex issues, and there are some significant problems with system reliability. For example, the refrigerant circulation volume in compression refrigeration mode is much larger than that in refrigerant pump heat pipe circulation, usually requiring a larger liquid receiver to adjust for the difference. In refrigerant pump refrigeration mode, incompletely evaporated refrigerant liquid entering the gas line between the evaporator and condenser can easily form a "liquid seal," increasing gas flow resistance and even affecting gas flow. This leads to problems such as increased pump head, decreased system efficiency ratio, and reduced system performance. Therefore, it is necessary to guide the refrigerant liquid from the evaporator outlet back to the liquid line as much as possible. When the refrigerant pump heat pipe operates at low outdoor temperatures, the low-temperature liquid refrigerant and lubricating oil returning from the outdoor condenser are prone to oil-liquid separation in the liquid receiver. In this case, the lubricating oil is not easily returned to the compressor during startup with the refrigerant liquid, which may cause oil shortage during compressor startup and, in severe cases, damage the compressor.

[0006] Because existing fluorine pump compression refrigeration systems have technical problems such as the inability to return oil to the compressor when the system is shut down, this invention studies and designs a fluorine pump compression dual-cycle refrigeration unit and a control method. Summary of the Invention

[0007] Therefore, the technical problem to be solved by the present invention is to overcome the defect of the existing fluorine pump compression refrigeration system that cannot return oil to the compressor when it is stopped, thereby providing a fluorine pump compression dual-cycle refrigeration unit and control method.

[0008] To address the above problems, the present invention provides a fluorine pump compression dual-cycle refrigeration unit, comprising:

[0009] The system includes a compressor, a refrigerant pump, a liquid receiver, and an oil return assembly. The oil return assembly is capable of recovering the oil-containing mixture in the liquid receiver and transporting it back to the compressor when the compressor and / or the refrigerant pump stops. The oil return assembly includes a floating body disposed inside the liquid receiver and capable of floating in the liquid within the liquid receiver to rise or fall with the liquid level. The floating body is provided with a suction port to draw in the oil-containing mixture at the liquid surface. When the compressor and / or the refrigerant pump stops, and the temperature of the liquid receiver is lower than a preset temperature, the upper layer of oil-containing mixture can be automatically discharged from the liquid receiver by utilizing the stratification of the oil.

[0010] In some implementations...

[0011] The oil return assembly also includes a hose and an oil return line. The upper end of the hose is connected to the floating body so that it can rise and fall together with the floating body to discharge the oil-containing mixture sucked in by the floating body. The lower end of the hose is connected to one end of the oil return line, which extends out of the liquid storage tank to guide the oil-containing mixture to the compressor.

[0012] In some implementations...

[0013] A one-way valve C is installed on the oil return line, and a heating element is installed on the oil return line. The heating element can heat the mixture of refrigerant and oil in the oil return line to make the refrigerant evaporate and separate the lubricating oil. The one-way valve C can only allow fluid to flow from the liquid storage tank to the heating element.

[0014] In some implementations...

[0015] It also includes an evaporator and an internal fan. The heating component includes fins and / or fins on a portion of the oil return pipe so that the portion of the pipe forms a finned tube and / or a finned tube. The finned tube and / or finned tube is located at the return air inlet of the evaporator. The internal fan drives the airflow at the return air inlet to exchange heat with the finned tube and / or finned tube.

[0016] In some implementations...

[0017] The finned tubes and / or finned tubes are disposed on the outside and / or inside of the evaporator. When the finned tubes and / or finned tubes are disposed inside the evaporator, the finned tubes and / or finned tubes are integrally formed with the heat exchange tubes of the evaporator.

[0018] In some implementations...

[0019] It also includes an oil separator, a first oil return pipe, and a second oil return pipe. The oil separator is located at the discharge end of the compressor and communicates with the discharge end. One end of the first oil return pipe is connected to the inner bottom of the oil separator, and the other end is connected to the finned tube and / or the finned tube. One end of the second oil return pipe is also connected to the finned tube and / or the finned tube and / or connected to the first oil return pipe. The other end of the second oil return pipe can be connected to the suction end of the compressor. After the refrigerant and oil mixture in the oil return pipe is separated by the finned tube and / or the finned tube, the refrigerant gas first enters the oil separator. When the oil return pipe returns oil again, the oil in the finned tube and / or the finned tube is recycled back into the oil separator. After the compressor starts, the oil in the oil separator can return to the suction end of the compressor through the first oil return pipe and the second oil return pipe.

[0020] In some implementations...

[0021] The compressor's suction end is connected to the fourth pipeline, and the other end of the second oil return pipe is connected to the fourth pipeline. The second oil return pipe is also equipped with an oil return throttling device. The first oil return pipe is also equipped with fins and / or ribs.

[0022] In some implementations...

[0023] It also includes a condenser, an inlet pipe, and an outlet pipe. The condenser is connected between the exhaust end of the compressor and the liquid storage tank. The oil separator is located between the exhaust end of the compressor and the condenser. One end of the inlet pipe is connected to the condenser, and the other end is connected to the top of the inside of the liquid storage tank, so as to introduce the refrigerant that has undergone heat exchange in the condenser into the liquid storage tank. One end of the outlet pipe is connected to the bottom of the inside of the liquid storage tank, and the other end is connected to one end of the refrigerant pump.

[0024] In some implementations...

[0025] It also includes a first pipeline, a second pipeline, a third pipeline, a fifth pipeline, a throttle valve, a one-way valve A, and a one-way valve B. The other end of the refrigerant pump is connected to one end of the evaporator through the first pipeline. The throttle valve is installed on the first pipeline. One end of the second pipeline is connected to the liquid outlet pipe, and the other end is connected to a position on the first pipeline located between the refrigerant pump and the throttle valve. The second pipeline is equipped with the one-way valve A, which only allows fluid to flow from the liquid outlet pipe to the first pipeline. The other end of the evaporator is connected to the third pipeline. The third pipeline is connected to the suction end of the compressor through the fourth pipeline. The third pipeline is also connected to the discharge end of the compressor through the fifth pipeline. The fifth pipeline is equipped with the one-way valve B, which only allows refrigerant fluid to flow from the suction end to the discharge end of the compressor.

[0026] The present invention also provides a control method for a refrigerant pump compression dual-cycle refrigeration unit as described above, comprising:

[0027] The detection steps include checking whether the compressor or refrigerant pump is shut down, and checking the temperature of the storage tank.

[0028] The judgment step is to determine the relationship between the temperature of the liquid storage tank and the preset temperature T0;

[0029] The control procedure involves starting the internal fan when the compressor or refrigerant pump is stopped and the temperature of the liquid storage tank is less than T0.

[0030] The fluorine pump compression dual-cycle refrigeration unit and control method provided by this invention have the following beneficial effects:

[0031] This invention relates to an oil return assembly installed inside a dual-cycle refrigeration unit with a refrigerant pump and compressor. This assembly recovers the oil-containing mixture from the receiver tank when the compressor and / or the refrigerant pump stops and transports it back to the compressor. Specifically, the oil return assembly includes a floating body located inside the receiver tank. The floating body floats in the liquid within the receiver tank, rising and falling with the liquid level. The floating body has a suction port to draw in the oil-containing mixture at the liquid surface. When the compressor and / or the refrigerant pump stops, and the temperature of the receiver tank is below a preset temperature, the upper layer of oil-containing mixture is automatically discharged from the receiver tank due to oil stratification. This allows for automatic oil return when the compressor or refrigerant pump stops and the temperature is low (under which conditions the lubricating oil and refrigerant liquid stratification is significant). The upper layer of oil-containing mixture is extracted by a floating body, greatly improving the separation efficiency of oil and refrigerant. This solves the problem of the inability to return oil to the compressor in a dual-cycle refrigeration unit with a refrigerant pump during shutdown. By utilizing the stratification of oil in the receiver tank under low-temperature conditions, the lubricating oil is effectively recovered and controlled, and the oil is separated and returned to the compressor oil sump, avoiding oil shortage in the compressor and solving the problem of poor oil return during compressor startup. This does not affect the reliability of the compressor refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the receiver tank under low-temperature conditions is safe and reliable. Furthermore, by using a heating element to heat the oil return pipeline, the separation efficiency of refrigerant and lubricating oil is further improved, ensuring that high-purity lubricating oil is recovered to the compressor. This does not affect the reliability of the compressor refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the receiver tank under low-temperature conditions is safe and reliable. Attached Figure Description

[0032] Figure 1 This is a system structure diagram of the fluorine pump compression dual-cycle refrigeration unit of the present invention;

[0033] Figure 2 yes Figure 1 Enlarged view of the liquid storage tank section (with a lot of lubricating oil, before liquid suction);

[0034] Figure 3 yes Figure 2 Enlarged view of the liquid storage tank section (with less lubricating oil, after liquid absorption).

[0035] The reference numerals in the attached figures are as follows:

[0036] 1. Compressor; 2. Receiver; 3. Condenser; 4. Throttling valve; 5. Evaporator; 6. Floating body; 7. Hoses; 8. Suction port; 9. Finned tubes and / or finned tubes; 10. Refrigerant pump; 11. Check valve A; 12. Check valve C; 13. Oil separator; 14. Internal fan; 15. Check valve B; 16. Return oil throttling element (capillary tube); 17. External fan;

[0037] 101. Liquid inlet pipe; 102. Liquid outlet pipe; 103. Oil return pipe; 104. Gas collection pipe; 105. First oil return pipe; 106. Second oil return pipe; 201. First pipeline; 202. Second pipeline; 203. Third pipeline; 204. Fourth pipeline; 205. Fifth pipeline. Detailed Implementation

[0038] 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.

[0039] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the exemplary embodiments according to this application. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0040] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0041] 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.

[0042] 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 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0043] 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.

[0044] like Figure 1-3 As shown, the present invention provides a fluorine pump compression dual-cycle refrigeration unit, which includes:

[0045] The system includes a compressor 1, a refrigerant pump 10, a liquid storage tank 2, and an oil return assembly. The oil return assembly can recover the oil-containing mixture (i.e., oil-rich liquid) in the liquid storage tank 2 and transport it back to the compressor 1 when the compressor 1 stops and / or the refrigerant pump 10 stops. The oil return assembly includes a floating body 6, which is disposed inside the liquid storage tank 2 and can float in the liquid in the liquid storage tank 2 so as to rise or fall with the liquid level. The floating body 6 is provided with a suction port 8 so as to suck up the oil-containing mixture at the liquid surface. When the compressor 1 stops and / or the refrigerant pump 10 stops, and the temperature of the liquid storage tank 2 is lower than a preset temperature, the upper layer of oil-containing mixture can be automatically discharged from the liquid storage tank 2 by utilizing the stratification of the oil.

[0046] This invention relates to an oil return assembly installed inside a dual-cycle refrigeration unit powered by a refrigerant pump. This assembly recovers the oil-containing mixture from the storage tank when the compressor and / or the refrigerant pump stops and transports it back to the compressor. Specifically, the oil return assembly includes a floating body located inside the storage tank. The floating body floats in the liquid within the storage tank, rising and falling with the liquid level. The floating body has a suction port to draw in the oil-containing mixture at the liquid surface. When the compressor and / or the refrigerant pump stops, and the temperature of the storage tank is below a preset temperature, the upper layer of oil-containing mixture can be automatically discharged using the oil stratification process. The receiver tank is designed to automatically extract the upper layer of oil, which has undergone preliminary separation, when the compressor or refrigerant pump stops and the system is at a low temperature (under which conditions the lubricating oil and refrigerant liquid are clearly separated). This significantly improves the separation efficiency of oil and refrigerant, solving the problem of the inability to return oil to the compressor in a dual-cycle refrigeration unit with a refrigerant pump when it stops. By utilizing the oil stratification in the receiver tank under low temperature conditions, the system effectively controls the recovery of lubricating oil, separating it and returning it to the compressor oil sump, thus preventing oil shortage in the compressor and solving the problem of poor oil return during compressor startup. This does not affect the reliability of the compressor refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the receiver tank under low temperature conditions is safe and reliable.

[0047] In some implementations...

[0048] The oil return assembly also includes a hose 7 and an oil return line 103. The upper end of the hose 7 is connected to the floating body 6 so that it can rise and fall together with the floating body 6 to discharge the oil-containing mixture sucked in by the floating body 6. The lower end of the hose 7 is connected to one end of the oil return line 103. The oil return line 103 extends out of the liquid storage tank 2 to guide the oil-containing mixture to the compressor 1.

[0049] The oil return assembly of the present invention further includes a hose and an oil return pipeline. The floating body can float in the liquid (partially on the liquid surface and partially below the liquid surface), preferably with a density less than that of the lubricating oil. This allows it to draw lubricating oil from the liquid surface through the suction port. The hose's structure allows its upper end to be connected to the floating body and float up and down together, so as to guide the oil-containing mixture drawn by the floating body downwards into the oil return pipeline and further back to the compressor. This effectively recovers the lubricating oil from the storage tank and delivers it to the compressor, ensuring the normal and reliable operation of the compressor.

[0050] The liquid storage tank of the present invention is provided with a float (floating body 6) and a hose 7. The float is connected to the oil return line 103 through the hose. The oil-rich liquid in the upper layer of the liquid storage tank 2 flows out of the liquid storage tank 2 through the float, the hose 7 and the oil return line 103.

[0051] The float and hose of the present invention are preferably made of low-density material. The float has a hollow structure and a liquid inlet 8 is provided in the upper middle part of the float to connect the internal space and the external space of the float. The hose 7 is connected to the lower center of the float. The density of the float and hose is lower than the density of the lubricating oil at the highest design operating temperature of the unit (the density of lubricating oil is usually negatively correlated with temperature).

[0052] The fluorine pump compression dual-cycle refrigeration unit of the present invention preferably further includes an oil return pipeline 103, one end of which is connected to the bottom of the inside of the liquid storage tank, and the other end is located between the oil outlet of the oil separator and the capillary inlet.

[0053] In some implementations...

[0054] A one-way valve C12 is provided on the oil return line 103, and a heating component is provided on the oil return line 103. The heating component can heat the mixture of refrigerant and oil in the oil return line 103 to make the refrigerant evaporate and separate the lubricating oil. The one-way valve C12 can only allow fluid to flow from the liquid storage tank 2 to the heating component.

[0055] This invention utilizes a one-way valve C installed on the oil return line, which allows fluid to flow only from the reservoir 2 to the heating element. This prevents fluid in the oil separator from entering the reservoir through the oil return line during compression or refrigerant pump mode, thus avoiding a short circuit to the condenser. Furthermore, this invention preferably uses a heating element to heat the oil return line, further improving the separation efficiency of refrigerant and lubricating oil. This ensures that high-purity lubricating oil is recovered into the compressor without affecting the reliability of compression refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the reservoir under low-temperature conditions is safe and reliable.

[0056] Preferably, the lubricating oil level in the upper part of the storage tank is higher than the lubricating oil level in the lower part of the oil separator, and the height of the heating element is lower than that of the oil separator, so that the oil-rich liquid in the upper part of the storage tank can automatically enter the heating element at a lower position through the one-way valve C under the action of gravity.

[0057] In some implementations...

[0058] It also includes an evaporator 5 and an internal fan 14. The heating component includes fins and / or fins on a portion of the pipe section on the oil return line 103, so that the portion of the pipe section forms a finned tube and / or a finned tube 9. The finned tube and / or finned tube 9 is located at the return air inlet of the evaporator 5. The internal fan 14 drives the airflow at the return air inlet to exchange heat with the finned tube and / or finned tube 9.

[0059] The present invention further enhances heat exchange by configuring the heating element to include fins and / or fins, thereby forming finned tubes and / or finned tubes in the oil return line. In particular, by setting the finned tubes and / or finned tubes at the return air inlet of the evaporator, the hotter gas from the evaporator return air can be used to heat the mixture of refrigerant and oil in the oil return line to evaporate the refrigerant, thereby achieving further separation of refrigerant and oil, improving the separation purity of lubricating oil, and improving the oil return efficiency of the compressor.

[0060] The return oil pipeline of the present invention is preferably provided with a heating component, which includes a finned tube and / or a ribbed tube. A heating component is also connected in series on the connecting pipeline between the oil outlet of the oil separator and the return oil pipeline.

[0061] The heating element is preferably located on the return air side of the hot air in the evaporator, so as to make full use of the heat of the indoor hot air to heat the oil-rich liquid inside the evaporation heating element, so that the refrigerant in the oil-rich liquid evaporates and vaporizes, thereby separating the lubricating oil.

[0062] In some implementations...

[0063] The finned tubes and / or finned tubes 9 are disposed on the outside and / or inside of the evaporator 5. When the finned tubes and / or finned tubes 9 are disposed inside the evaporator 5, the finned tubes and / or finned tubes 9 are integrally formed with the heat exchange tubes of the evaporator 5.

[0064] The finned tubes and / or finned tubes of the present invention can be located outside and / or inside the evaporator. These are two different arrangements of the finned tubes and / or finned tubes of the present invention. As long as they are located at the return air inlet of the evaporator, the higher temperature gas at the return air inlet can be effectively used to heat the oil return pipeline. When the finned tubes and / or finned tubes are arranged inside the evaporator, it is preferable that they are integrally formed with the heat exchange tubes of the evaporator to achieve integral forming. However, the refrigerant in the heat exchange tubes of the evaporator does not mix with the fluid in the finned tubes and / or finned tubes and is not connected.

[0065] Preferably, the heating component of this invention can be integrally formed with the evaporator, that is, a separate branch on the finned tube heat exchanger type evaporator is used to connect to the oil return pipe, that is, the oil return port of the oil separator is connected to one end of the branch, and the other end of the branch is connected to the liquid return pipe of the liquid storage tank (not shown in the figure).

[0066] In some implementations...

[0067] It also includes an oil separator 13, a first oil return pipe 105, and a second oil return pipe 106. The oil separator 13 is located at the discharge end of the compressor 1 and communicates with the discharge end. One end of the first oil return pipe 105 communicates with the inner bottom of the oil separator 13, and the other end communicates with the finned tube and / or the finned tube 9. One end of the second oil return pipe 106 also communicates with the finned tube and / or the finned tube 9 and / or communicates with the first oil return pipe 105. The other end of the second oil return pipe 106 can be connected to... The refrigerant and oil mixture in the oil return line 103 is separated by the finned tube and / or finned tube 9 and then the refrigerant gas first enters the oil separator 13. When the oil return line 103 returns oil again, the oil in the finned tube and / or finned tube 9 is recycled back into the oil separator 13. After the compressor starts, the oil in the oil separator 13 can return to the suction end of the compressor 1 through the first oil return line 105 and the second oil return line 106.

[0068] This is a further preferred structural form of the refrigeration unit of the present invention, namely, the first and second oil return pipes of the oil separator are respectively or both connected to the finned tube and / or the finned tube, which allows the refrigerant and oil mixture in the oil return line to be separated after passing through the finned tube and / or the finned tube. The refrigerant gas first enters the oil separator through the first oil return pipe. When the oil return line returns oil again, the oil in the finned tube and / or the finned tube is recycled back into the oil separator. After the compressor starts, the oil in the oil separator can return to the suction end of the compressor through the first and second oil return pipes, ultimately achieving the effect of separating the lubricating oil in the liquid receiver and leading it to the suction end of the compressor or the oil sump, thus ensuring the reliable operation of the compressor.

[0069] This invention adds a novel liquid storage tank to a refrigerant pump compression dual-cycle refrigeration unit. Through an oil return assembly, which includes a low-density hollow float (floating body 6) and a matching hose 7, the oil-rich liquid on the upper layer of the storage tank is collected under low-temperature conditions and transported to the oil separator 13 by gravity. A heating element is installed on the oil return pipeline 103. The refrigerant in the oil-rich liquid is vaporized by heat exchange between the indoor hot air and the heating element. The separated lubricating oil floats on the upper layer and enters the oil separator 13, waiting for the compressor to start and suck it back.

[0070] When the compressor and / or refrigerant pump stops, the low temperature conditions cause the oil-rich liquid and refrigerant liquid in the upper layer of the receiver tank to separate. The low-density float sinks more in the oil-rich layer and can draw up the oil-rich liquid. It enters the heating element through the hose and uses hot air to separate the refrigerant and lubricating oil. The residual lubricating oil is stored in the oil separator, and the vaporized refrigerant gas enters the condenser to be cooled and liquefied.

[0071] As the oil-rich liquid is drawn into the float, the oil-rich layer on the upper part of the storage tank becomes less and less. The float sinks to a shallower depth in the denser refrigerant liquid, causing the liquid inlet on the float to be exposed above the oil-rich layer, thus stopping the absorption of the oil-rich liquid and achieving the function of automatically stopping the return of oil.

[0072] The beneficial effect is that when the compressor and / or refrigerant pump stops, the low temperature conditions cause the oil-rich liquid and refrigerant liquid in the upper layer of the receiver tank to separate. The low-density float sinks more in the oil-rich layer and can draw up the oil-rich liquid, which enters the heating element through the hose 7. The hot air is used to separate the refrigerant and lubricating oil. The residual lubricating oil is stored in the oil separator, and the vaporized refrigerant gas enters the condenser to cool and liquefy. This does not affect the reliability of the compressor refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the receiver tank under low temperature conditions is safe and reliable. When the compressor starts refrigeration, the separated lubricating oil can be returned to the compressor oil sump in time, ensuring the reliable operation of the compressor refrigeration.

[0073] This solves the problem of the compressor being unable to return oil when it is stopped and / or under low temperature conditions.

[0074] In some implementations...

[0075] The suction end of the compressor 1 is connected to the fourth pipeline 204, and the other end of the second oil return pipe 106 is connected to the fourth pipeline 204. The second oil return pipe 106 is also provided with an oil return throttling device 16. The first oil return pipe 105 is also provided with fins and / or ribs.

[0076] This is a further preferred structural form of the refrigeration unit of the present invention, namely, the other end of the second oil return pipe is connected to the fourth pipe, which enables the lubricating oil in the second oil return pipe to be drawn into the compressor by drawing fluid from the fourth pipe when the compressor starts in compressor mode; the first oil return pipe of the present invention is preferably also provided with fins and / or ribs, which enables this section of the pipe to also heat the mixture of lubricating oil and refrigerant liquid, thereby turning the refrigerant into gas, realizing effective and complete separation between lubricating oil and refrigerant, and further improving the separation effect.

[0077] In some implementations...

[0078] It also includes a condenser 3, an inlet pipe 101, and an outlet pipe 102. The condenser 3 is connected between the exhaust end of the compressor 1 and the liquid storage tank 2. The oil separator 13 is disposed between the exhaust end of the compressor 1 and the condenser 3. One end of the inlet pipe 101 is connected to the condenser 3 and the other end is connected to the top of the inside of the liquid storage tank 2 so as to introduce the refrigerant that has undergone heat exchange in the condenser 3 into the liquid storage tank 2. One end of the outlet pipe 102 is connected to the bottom of the inside of the liquid storage tank 2 and the other end is connected to one end of the refrigerant pump 10.

[0079] This is a further preferred structural form of the present invention, wherein the inlet pipe is connected to the top of the inside of the liquid storage tank, which can introduce the refrigerant that has undergone heat exchange in the condenser into the liquid storage tank, and the outlet pipe is connected to the bottom of the inside of the liquid storage tank, which can export the refrigerant (preferably liquid refrigerant) in the liquid storage tank to the refrigerant pump.

[0080] like Figure 2-3 As shown, the liquid storage tank includes an inlet pipe, an outlet pipe, and a return pipe. The outlet pipe and the return pipe are preferably located at the bottom of the liquid storage tank; the inlet pipe is preferably located at the top and / or bottom of the liquid storage tank.

[0081] In some implementations...

[0082] It also includes a first pipeline 201, a second pipeline 202, a third pipeline 203, a fifth pipeline 205, a throttle valve 4, a one-way valve A11, and a one-way valve B15. The other end of the refrigerant pump 10 is connected to one end of the evaporator 5 via the first pipeline 201. The throttle valve 4 is installed on the first pipeline 201. One end of the second pipeline 202 is connected to the outlet pipe 102, and the other end is connected to the first pipeline 201 at a position between the refrigerant pump 10 and the throttle valve 4. The evaporator 5 is equipped with a one-way valve A11 that allows fluid to flow only from the outlet pipe 102 to the first pipe 201; the other end of the evaporator 5 is connected to the third pipe 203, the third pipe 203 is connected to the suction end of the compressor 1 through the fourth pipe 204, and the third pipe 203 is also connected to the discharge end of the compressor 1 through the fifth pipe 205. The fifth pipe 205 is equipped with a one-way valve B15 that allows refrigerant fluid to flow only from the suction end to the discharge end of the compressor 1.

[0083] This is a further preferred structural form of the refrigeration system of the present invention, namely, one-way valve A is the pipeline for refrigerant flow in compression refrigeration mode, and one-way valve B is the pipeline for refrigerant flow in refrigerant pump mode. One-way valve A effectively ensures that the refrigerant at the outlet end of the refrigerant pump will not directly return to the inlet end of the refrigerant pump, and one-way valve B effectively ensures that the refrigerant at the outlet end of the compressor will not directly return to the inlet end of the compressor.

[0084] like Figure 1-3 As shown, the refrigerant pump compression dual-cycle refrigeration unit consists of a compressor, oil separator, condenser, liquid receiver, refrigerant pump, expansion valve, and evaporator connected in sequence.

[0085] The refrigerant pump compression dual-cycle refrigeration unit also includes a capillary tube for oil return. The oil separator is connected between the compressor's exhaust port and the condenser's inlet. The oil separator's inlet is connected to the compressor's exhaust port, and the oil separator's outlet is connected to the condenser's inlet. The capillary tube is connected between the oil separator's outlet and the compressor's suction port.

[0086] The fluorine pump compression dual-cycle refrigeration unit also includes a one-way valve A. The outlet pipe of the liquid storage tank is connected to the inlet of the fluorine pump and the inlet of the one-way valve A. The outlet of the one-way valve A is connected between the outlet of the fluorine pump and the inlet of the throttle valve. The flow direction of the one-way valve A is only allowed to be from the outlet pipe of the liquid storage tank to the inlet of the throttle valve.

[0087] The refrigerant pump compression refrigeration system also includes a one-way valve B, which is connected in parallel to bypass the compressor. The inlet and outlet of the one-way valve B are connected to the suction port and discharge port of the compressor, respectively. The flow direction of the one-way valve B is only allowed from the compressor inlet to the compressor outlet.

[0088] The present invention also provides a control method for a refrigerant pump compression dual-cycle refrigeration unit as described above, comprising:

[0089] The detection steps include detecting whether the compressor or the refrigerant pump is shut down, and detecting the temperature of the liquid storage tank 2.

[0090] The judgment step is to determine the relationship between the temperature of the liquid storage tank 2 and the preset temperature T0;

[0091] The control step involves controlling the internal fan 14 to start when the compressor or refrigerant pump is stopped, and the temperature of the liquid storage tank 2 is less than T0, and when the internal fan 14 is included.

[0092] This invention determines the operating status of the compressor and / or refrigerant pump. When the compressor or refrigerant pump is shut down and the temperature of the liquid storage tank 2 is less than T0 (this state is most prone to oil-refrigerant stratification, thus the purity and efficiency of oil absorption and separation are higher), it controls the on / off state of the oil return component to allow the oil-rich liquid in the upper layer of the low-temperature liquid storage tank to enter the heating component. Hot air is used to separate the refrigerant and lubricating oil. The system control is simple and reliable, and does not affect the reliability of the compressor refrigeration or refrigerant pump refrigeration operation. The separation and recovery of lubricating oil in the liquid storage tank under low-temperature conditions is safe and reliable.

[0093] The working principle of the fluorine pump compression dual-cycle refrigeration unit of the present invention, as well as the circulation path and working status of the components of the refrigeration system, are described below:

[0094] A) such as Figure 1 As shown, the main refrigerant path in the fluorine pump refrigeration mode is: fluorine pump → expansion valve → evaporator → check valve B → oil separator → condenser → liquid receiver → fluorine pump.

[0095] illustrate:

[0096] a1) Part of the refrigerant at the evaporator outlet will also enter the oil separator and then the condenser through the capillary tube. In other words, this flow path is in parallel with the flow path of check valve B, but the refrigerant flow at check valve B is larger, and the refrigerant flow in the flow path where the capillary tube is located can be ignored.

[0097] a2) When the fluorine pump is working, its outlet pressure is higher than its inlet pressure. This means that at this time, the one-way valve A is in a reverse high-pressure cut-off and non-flow state. In other words, the one-way valve A can prevent the refrigerant liquid at the outlet of the fluorine pump from directly short-circuiting back to the inlet of the fluorine pump.

[0098] a3) The outlet pressure of the fluorine pump is the highest pressure in the system, and the inlet pressure of the fluorine pump is the lowest pressure in the system. Therefore, the pressure at the inlet of the one-way valve C and the inlet of the condenser can be approximated as the pressure inside the oil separator, which is the pressure inside the high-pressure liquid storage tank. Thus, the one-way valve C is in a reverse high-pressure shut-off and non-flowing state at this time.

[0099] B) such as Figure 1 As shown, the main refrigerant path in compression refrigeration mode is: compressor → oil separator → condenser → liquid receiver → check valve A → expansion valve → evaporator → compressor.

[0100] illustrate:

[0101] b1) The lubricating oil separated in the oil separator returns to the compressor suction port through the capillary tube under the pressure difference between high pressure and low pressure. Sometimes a small amount of high-pressure refrigerant gas will return to the compressor suction port through the capillary tube, but this can be ignored.

[0102] b2) Part of the refrigerant liquid in the outlet pipe of the liquid receiver will also flow through the impeller gap of the fluorine pump. That is, the one-way valve A and the fluorine pump are connected in parallel at this time, but the refrigerant liquid flow at the one-way valve A is larger, and the refrigerant liquid flow through the fluorine pump can be ignored.

[0103] (b3) The compressor discharge port pressure is at the highest point of the system pressure, and the compressor suction port pressure is at the lowest point of the system pressure. The pressure gradually decreases along the direction of refrigerant flow. The inlet of the expansion valve is high pressure and the outlet is low pressure. Because the outlet of check valve C is connected to the high-pressure oil separator, while the inlet of check valve C is connected to the low-pressure liquid receiver (actually, the liquid receiver is also at high pressure at this time, but the pressure inside the liquid receiver is lower than the pressure inside the oil separator. The pressure difference between the two is mainly due to the change in refrigerant flow resistance caused by the condenser), check valve C is in a reverse high-pressure cut-off and non-flowing state at this time.

[0104] The principle of oil return control in this invention is explained as follows:

[0105] Under low-temperature conditions, the refrigerant liquid and lubricating oil in the receiver tank will separate into layers. The low-density lubricating oil floats on top of the high-density refrigerant liquid, while the even lower-density float floats on the oil-rich layer. Therefore, the upper layer of the receiver tank is oil-rich liquid. The float and hose are made of low-density material, and the float has a suction port connected to the hose. The density of the float and hose is lower than the density of the lubricating oil at the highest design operating temperature of the unit (the density of lubricating oil is usually negatively correlated with temperature). As analyzed above, the one-way valve C cannot flow during the operation of the refrigerant pump or compressor. Therefore, the one-way valve C can only flow when both the refrigerant pump and compressor are stopped. Obviously, when the temperature around the receiver tank is high, if the low-temperature condition is not reached, the oil in the receiver tank is less likely to separate into layers or the separation phenomenon is not obvious. The upper layer of oil-rich liquid in the receiver tank is not large, so the suction port of the float is unlikely to absorb oil-rich liquid, and automatic gravity oil return cannot be achieved. In this case, the system is not required to have an automatic oil return function.

[0106] 1) During compressor and refrigerant pump shutdown, and under low temperature conditions (which is also the condition for internal fan to be turned on), low temperature stratification occurs in the oil in the receiver tank. The upper layer of rich oil liquid in the receiver tank enters through the float's suction port under gravity and fills the return oil pipe. Figure 2 (as shown);

[0107] 2) Turn on the internal fan and use the hot air in the room to heat the refrigerant liquid inside the heating component to evaporate into gas. The refrigerant gas enters the low temperature condenser to cool and liquefy and then returns to the liquid storage tank. The lubricating oil is separated and left in the heating component, and more oil-rich liquid continuously flows in to replenish the heating component. The separated lubricating oil is gradually pushed into the oil separator for storage.

[0108] 3) As the rich oil layer in the storage tank decreases, the float's suction port exposes the rich oil layer, and the rich oil liquid no longer enters the heating components (e.g., Figure 3As shown), the refrigerant in the heating components is heated and vaporized, enters the condenser for cooling and liquefaction, and then returns to the liquid receiver. Therefore, the separated lubricating oil remains in the oil return pipe and / or oil separator, waiting to be drawn back to the compressor's oil sump after the compressor starts.

[0109] In the refrigerant pump refrigeration mode, lubricating oil is continuously collected and separated, and stored in the oil return pipe and / or oil separator. This does not affect the reliable operation of the refrigerant pump refrigeration mode. As more and more lubricating oil accumulates in the oil return pipe and / or oil separator, it awaits the compressor to start running, effectively ensuring the reliability of the compressor's start-up and operation. In the refrigerant pump refrigeration mode, the amount of lubricating oil flowing in the system decreases, reducing the flow resistance of the refrigerant pump refrigeration operation and improving the energy efficiency ratio of the refrigerant pump refrigeration. Therefore, the oil return control proposed in this case is safe and reliable, and can fully guarantee the oil return effect of the compressor.

[0110] 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 dual cycle refrigeration unit characterized by: Comprise: Compressor (1), fluorine pump (10), liquid tank (2) and oil return assembly, the oil return assembly can recover the oil-containing mixture in the liquid tank (2) when the compressor (1) stops and / or the fluorine pump (10) stops and can be delivered to the compressor (1); the oil return assembly comprises a floating body (6), the floating body (6) is arranged in the inside of the liquid tank (2), and the floating body (6) can float in the liquid in the liquid tank (2) to be integrated with the liquid level height rises or falls, the floating body (6) is provided with a liquid suction port (8), so that the oil-containing mixture at the liquid level can be sucked in, and when the compressor (1) stops and / or the fluorine pump (10) stops, and the temperature of the liquid tank (2) is lower than the preset temperature, the upper oil-containing mixture in the liquid tank (2) can be automatically guided out by using the oil layering; The oil return assembly further comprises an oil return pipeline (103), the oil return pipeline (103) is provided with a heating component, the heating component can heat the mixed liquid of refrigerant and oil in the oil return pipeline (103) to make the refrigerant evaporate, and separate out the lubricating oil, and further comprises an evaporator (5), the heating component comprises fins and / or fins arranged on the part of the pipe section of the oil return pipeline (103), so that the part of the pipe section forms a finned tube and / or finned tube (9), and the finned tube and / or finned tube (9) is arranged at the air return port of the evaporator (5).

2. The fluorine pump compression double-cycle refrigeration unit according to claim 1, wherein: The oil return assembly further comprises a hose (7), the upper end of the hose (7) is connected with the floating body (6) to be integrated with the floating body (6) to be lifted, so that the oil-containing mixture sucked by the floating body (6) can be guided out, and the lower end of the hose (7) is communicated with one end of the oil return pipeline (103), and the oil return pipeline (103) extends out of the liquid tank (2) to guide the oil-containing mixture to the compressor (1).

3. The fluorine pump compression double-cycle refrigeration unit according to claim 2, wherein: The oil return pipeline (103) is provided with a one-way valve C (12), and the one-way valve C (12) can only allow fluid to flow from the liquid tank (2) to the heating component.

4. The fluorine pump compression double-cycle refrigeration unit according to claim 3, wherein: Further comprising an inner fan (14), and the inner fan (14) drives the air flow at the air return port to exchange heat with the finned tube and / or finned tube (9).

5. The fluorine pump compression double-cycle refrigeration unit according to claim 4, wherein: The finned tube and / or finned tube (9) is arranged outside and / or inside the evaporator (5), and when the finned tube and / or finned tube (9) is arranged inside the evaporator (5), the finned tube and / or finned tube (9) is integrally formed with the heat exchange pipe of the evaporator (5).

6. The fluorine pump compression double-cycle refrigeration unit according to claim 4, wherein: Also comprising an oil separator (13), a first oil return pipe (105) and a second oil return pipe (106), the oil separator (13) is arranged at the exhaust end of the compressor (1) and communicates with the exhaust end, one end of the first oil return pipe (105) communicates with the inner bottom of the oil separator (13) and the other end communicates into the finned tube and / or finned tube (9), one end of the second oil return pipe (106) also communicates into the finned tube and / or finned tube (9) and / or communicates into the first oil return pipe (105), the other end of the second oil return pipe (106) can communicate to the suction end of the compressor (1), after the mixture of refrigerant and oil in the oil return pipeline (103) is separated by the finned tube and / or finned tube (9), the refrigerant gas first enters the oil separator (13), the next time the oil return pipeline (103) returns oil, the oil in the finned tube and / or finned tube (9) is recycled into the oil separator (13), after the compressor starts, the oil in the oil separator (13) can return to the suction end of the compressor (1) through the first oil return pipe (105) and the second oil return pipe (106).

7. The fluorine pump compression double-cycle refrigeration unit according to claim 6, characterized in that: The suction end of the compressor (1) communicates with a fourth pipeline (204), the other end of the second oil return pipe (106) communicates to the fourth pipeline (204), and an oil return throttling member (16) is further arranged on the second oil return pipe (106); the first oil return pipe (105) is also provided with fins and / or fins.

8. The fluorine pump compression double-cycle refrigeration unit according to claim 7, characterized in that: Also comprising a condenser (3), an inlet pipe (101) and an outlet pipe (102), the condenser (3) is connected between the exhaust end of the compressor (1) and the liquid storage tank (2), the oil separator (13) is arranged between the exhaust end of the compressor (1) and the condenser (3), one end of the inlet pipe (101) communicates with the condenser (3) and the other end communicates with the inner top end of the liquid storage tank (2), so as to guide the refrigerant in the condenser (3) after heat exchange into the liquid storage tank (2), one end of the outlet pipe (102) communicates with the inner bottom end of the liquid storage tank (2) and the other end communicates to one end of the fluorine pump (10).

9. The fluorine pump compression double-cycle refrigeration unit according to claim 8, characterized in that: Also include the first pipeline (201), the second pipeline (202), the third pipeline (203), the fifth pipeline (205), the throttle valve (4), one-way valve A (11) and one-way valve B (15), the other end of the fluorine pump (10) is communicated to one end of the evaporator (5) through the first pipeline (201), the throttle valve (4) is arranged on the first pipeline (201), one end of the second pipeline (202) is communicated to the liquid outlet pipe (102), the other end is communicated to the first pipeline (201) between the fluorine pump (10) and the throttle valve (4), the second pipeline (202) is provided with the one-way valve A (11) allowing fluid to flow from the liquid outlet pipe (102) to the first pipeline (201) only; The other end of the evaporator (5) is communicated to the third pipeline (203), the third pipeline (203) is communicated to the suction end of the compressor (1) through the fourth pipeline (204), the third pipeline (203) is also communicated to the exhaust end of the compressor (1) through the fifth pipeline (205), the fifth pipeline (205) is provided with the one-way valve B (15) allowing refrigerant fluid to flow from the suction end of the compressor (1) to the exhaust end only.

10. A method of controlling a fluoro pump compression dual cycle chiller unit as claimed in any one of claims 4 to 9, characterised by: It includes: The detection step detects whether the compressor is stopped or the fluorine pump is stopped, and detects the temperature of the liquid storage tank (2); The judgment step judges the relationship between the temperature of the liquid storage tank (2) and the preset temperature T0; The control step controls the inner fan (14) to start when the compressor is stopped or the fluorine pump is stopped, and the temperature of the liquid storage tank (2) is less than T0.

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