Chiller system and oil return control method

Abstract

This invention provides a chiller system and an oil return control method. The chiller system includes: a compressor and a heat exchanger, the outlet of the heat exchanger being connected to the compressor; a gas-liquid separator, the inlet of which is connected to the exhaust port of the compressor; the gas-liquid separator has a first separation port for communication with the inlet of the heat exchanger; wherein at least a portion of the outlet of the heat exchanger is selectively connected to or disconnected from the inlet, so that when at least a portion of the outlet of the heat exchanger is connected to the inlet, the fluid flowing out of at least a portion of the outlet of the heat exchanger exchanges heats the fluid discharged through the exhaust port. The technical solution provided by this invention can solve the technical problem of low separation efficiency of refrigerant oil and refrigerant in existing chiller systems.

Description

Technical Field

[0001] This invention relates to the field of chiller technology, and more specifically, to a chiller system and an oil return control method. Background Technology

[0002] Currently, for screw chillers that use either flooded shell-and-tube or falling film shell-and-tube heat exchangers, chilled water is produced through shell-and-tube heat exchangers and screw compressors are used. The refrigeration oil in the shell-and-tube heat exchangers is used in the screw compressor for functions such as lubrication, sealing, cooling, and load control.

[0003] However, because refrigeration oil and refrigerant are miscible, the refrigerant in the refrigeration cycle of a chiller often carries refrigeration oil. To avoid compressor oil shortage, the conventional solution is to install a gas-liquid separator at the compressor discharge port to separate the refrigeration oil from the refrigerant gas and allow the refrigeration oil to flow back into the compressor. However, due to the high temperature at the compressor discharge port, the oil droplets are smaller, making it difficult for the refrigeration oil to separate from the refrigerant. This means the oil separator cannot completely separate the oil and gas, and some refrigeration oil always enters the refrigerant cycle with the refrigerant, leading to compressor oil shortage. Simultaneously, because the refrigerant carries refrigeration oil in the refrigerant cycle, refrigeration oil accumulates in the shell-and-tube heat exchanger during the refrigeration cycle. This accumulation affects the heat exchange effect within the chiller shell and tube, further impacting the chiller's heat exchange efficiency. Summary of the Invention

[0004] The main objective of this invention is to provide a chiller system and an oil return control method to solve the technical problem of low separation efficiency of refrigeration oil and refrigerant in existing chiller systems.

[0005] To achieve the above objectives, according to one aspect of the present invention, a chiller unit system is provided, comprising:

[0006] The compressor and heat exchanger are connected, with the outlet of the heat exchanger connected to the compressor.

[0007] A gas-liquid separator, the inlet of which is connected to the exhaust port of the compressor; the gas-liquid separator has a first separation port, which is used to communicate with the inlet of the heat exchanger;

[0008] The outlet of the heat exchanger may be selectively connected to or disconnected from the inlet, so that when the outlet of the heat exchanger is connected to the inlet, the fluid flowing out of the outlet of the heat exchanger exchanges with the fluid discharged through the exhaust port.

[0009] Furthermore, the outlet portion of the heat exchanger includes a first outlet and a second outlet spaced apart, the second outlet being located below the first outlet. The first outlet is in communication with the compressor, and the second outlet forms at least a portion of the outlet portion of the heat exchanger; and / or,

[0010] The chiller system also includes a first valve body disposed at at least a portion of the outlet of the heat exchanger, the first valve body being used to control the connection or disconnection between at least a portion of the outlet of the heat exchanger and the inlet; and / or,

[0011] The chiller system also includes a pump body, which is located at least a portion of the outlet of the heat exchanger and is used to direct the fluid flowing out of at least a portion of the outlet of the heat exchanger into the inlet.

[0012] Furthermore, the inlet and outlet are connected via an exhaust pipe; the chiller system also includes:

[0013] Pressure detection element, installed at the exhaust pipe; and / or,

[0014] Temperature sensing element, installed at the exhaust pipe; and / or,

[0015] A liquid level sensor is installed inside the heat exchanger to detect the refrigerant level within the heat exchanger.

[0016] Furthermore, the gas-liquid separator also has a second separation port, located below the first separation port and used to connect to the compressor; the chiller system also includes:

[0017] An oil filter, located at the second separation port, is used to filter impurities in the fluid discharged from the second separation port; and / or,

[0018] The second valve body is located at the second separation port and is used to control the connection or disconnection between the second separation port and the compressor.

[0019] Furthermore, the chiller system also includes:

[0020] An ejector is used to connect to the compressor's suction port; the ejector's inlet can be selectively connected to or disconnected from the heat exchanger's second outlet, and the ejector's ejector port can be selectively connected to or disconnected from the exhaust port.

[0021] The ejector has an ejection state in which the inlet of the ejector is connected to the second outlet, the ejector port is connected to the exhaust port, and the ejector is connected to the intake port, and a closed state in which the inlet of the ejector is disconnected from the second outlet and the ejector port is disconnected from the exhaust port.

[0022] According to another aspect of the present invention, a return oil control method is provided, applicable to the chiller system provided above, the return oil control method comprising:

[0023] Obtain at least one of the following: the amount of refrigerant in the heat exchanger of the chiller system and the discharge temperature of the compressor of the chiller system.

[0024] Depending on at least one of the refrigerant quantity and exhaust temperature, control the connection or disconnection between at least a portion of the heat exchanger outlet and the inlet of the gas-liquid separator in the chiller system.

[0025] Furthermore, the exhaust temperature condition includes the compressor's exhaust temperature; and / or,

[0026] Exhaust temperature conditions include compressor exhaust superheat; and / or,

[0027] The refrigerant quantity information includes the refrigerant level inside the heat exchanger.

[0028] Further, depending on at least one of the refrigerant quantity and exhaust temperature, controlling the connection or disconnection between at least a portion of the heat exchanger outlet and the inlet of the gas-liquid separator in the chiller system includes:

[0029] Obtain the refrigerant level in the heat exchanger, the compressor discharge temperature, and the compressor operating time;

[0030] Determine whether the chiller system simultaneously meets the first preset judgment condition, the second preset judgment condition, the third preset judgment condition, and the fourth preset judgment condition;

[0031] When the chiller system simultaneously meets the first preset judgment condition, the second preset judgment condition, the third preset judgment condition and the fourth preset judgment condition, at least a portion of the outlet of the heat exchanger is connected to the inlet.

[0032] The first preset judgment condition is that the compressor's exhaust temperature is greater than a preset temperature value; the second preset judgment condition is that the compressor's exhaust superheat is greater than a preset superheat value; the third preset judgment condition is that the refrigerant level in the heat exchanger is greater than the first preset level value; and the fourth preset judgment condition is that the compressor's running time is greater than a preset duration value.

[0033] Further, determining whether the chiller system meets the first preset judgment condition includes: acquiring the compressor's exhaust temperature within a first preset temperature measurement period; determining whether the compressor's exhaust temperature within the first preset temperature measurement period is greater than a preset temperature value; when the compressor's exhaust temperature within the first preset temperature measurement period is greater than the preset temperature value, determining that the chiller system meets the first preset judgment condition; and / or,

[0034] Determining whether the chiller system meets the second preset judgment condition includes: obtaining the compressor's exhaust superheat within a second preset temperature measurement period; determining whether the compressor's exhaust superheat within the second preset temperature measurement period is greater than a preset superheat; when the compressor's exhaust superheat within the second preset temperature measurement period is greater than the preset superheat, determining that the chiller system meets the second preset judgment condition; and / or,

[0035] The ratio of the first preset liquid level value to the height of the storage cavity of the heat exchanger used to store refrigerant is greater than 0 and less than or equal to 0.3.

[0036] Furthermore, the preset temperature value is greater than or equal to 60℃ and less than or equal to 100℃; and / or,

[0037] The preset superheat is greater than 0°C and less than or equal to 30°C; and / or,

[0038] The preset duration is greater than or equal to 30 minutes.

[0039] Furthermore, the oil return control method also includes:

[0040] Obtain at least one of the following: refrigerant level in the heat exchanger, compressor discharge temperature, and compressor operating status;

[0041] Determine whether the chiller system meets at least one of the fifth, sixth, and seventh preset judgment conditions;

[0042] If the chiller system meets at least one of the fifth, sixth, or seventh preset judgment conditions, at least a portion of the outlet of the heat exchanger is disconnected from the inlet.

[0043] The fifth preset judgment condition is that the compressor's exhaust superheat is less than or equal to the preset superheat; the sixth preset judgment condition is that the refrigerant level in the heat exchanger is less than the second preset level value; and the seventh preset judgment condition is that the compressor is in a closed state.

[0044] Further, determining whether the chiller system meets the fifth preset judgment condition includes: obtaining the compressor's exhaust superheat within a third preset temperature measurement time range; determining whether the compressor's exhaust superheat within the third preset temperature measurement time range is all less than or equal to a preset superheat; when the compressor's exhaust superheat within the third preset temperature measurement time range is all less than or equal to the preset superheat, determining that the chiller system meets the fifth preset judgment condition; and / or,

[0045] The ratio of the second preset liquid level value to the height of the heat exchanger's storage cavity for storing refrigerant is greater than 0 and less than or equal to 0.3.

[0046] The technical solution of this invention firstly improves the oil return efficiency and system reliability of the chiller system. By establishing a selectable connection between the gas-liquid separator and the heat exchanger, when at least a portion of the heat exchanger outlet is connected to the gas-liquid separator inlet, the cooling capacity of the fluid flowing out of the heat exchanger can be effectively utilized to exchange heat with the heat of the compressor exhaust. This heat exchange reduces the exhaust temperature, thereby increasing the diameter of the fluid flowing into the gas-liquid separator inlet, which in turn improves the gas-liquid separation efficiency of the gas-liquid separator, increases the recycling rate of the refrigerant oil, reduces the accumulation of refrigerant oil in the heat exchanger, and thus improves heat exchange efficiency and avoids compressor failures caused by oil shortage. Secondly, by controlling the connection state between the heat exchanger outlet and the gas-liquid separator inlet, the oil return and heat exchange strategies can be optimized under different operating conditions, thereby improving the overall system energy efficiency. Furthermore, this setup can also cool the high-temperature refrigerant discharged from the compressor, further improving the condensation effect. Therefore, the technical solution of this invention can solve the technical problem of low refrigerant oil and refrigerant separation efficiency in existing chiller systems. Attached Figure Description

[0047] The accompanying drawings, which form part of this application, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings:

[0048] Figure 1 A schematic diagram of the structure of a chiller unit system according to Embodiment 1 of the present invention is shown;

[0049] Figure 2 A schematic diagram of the steps of the oil return control method provided according to Embodiment 2 of the present invention is shown.

[0050] The above figures include the following reference numerals:

[0051] 10. Compressor; 11. Exhaust port; 12. Inlet port; 13. Oil return port;

[0052] 20. Heat exchanger; 21. First outlet; 22. Second outlet;

[0053] 30. Gas-liquid separator; 31. First separation port; 32. Second separation port; 33. Inlet;

[0054] 40. First valve body;

[0055] 50. Pump body;

[0056] 60. Pressure testing components;

[0057] 70. Temperature sensing components;

[0058] 80. Second valve body;

[0059] 90. Ejector;

[0060] 100. Third valve body;

[0061] 110. Fourth valve body;

[0062] 120. Oil filter;

[0063] 130. Air heat exchanger;

[0064] 140. Electronic expansion valve;

[0065] 150. Exhaust pipe. Detailed Implementation

[0066] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0067] like Figure 1 As shown, Embodiment 1 of the present invention provides a chiller system, which includes a compressor 10, a heat exchanger 20, and a gas-liquid separator 30. The outlet of the heat exchanger 20 is connected to the compressor 10. The inlet 33 of the gas-liquid separator 30 is connected to the exhaust port 11 of the compressor 10; the gas-liquid separator 30 has a first separation port 31, which is used to communicate with the inlet of the heat exchanger 20. At least a portion of the outlet of the heat exchanger 20 can be selectively connected to or disconnected from the inlet 33, so that when at least a portion of the outlet of the heat exchanger 20 is connected to the inlet 33, the fluid flowing out of at least a portion of the outlet of the heat exchanger 20 exchanges heat with the fluid discharged through the exhaust port 11.

[0068] The chiller system provided in Embodiment 1 of this invention firstly improves the oil return efficiency and system reliability of the chiller system. By establishing a selectable connection between the gas-liquid separator 30 and the heat exchanger 20, when at least a portion of the outlet of the heat exchanger 20 is connected to the inlet 33 of the gas-liquid separator 30, the cooling capacity of the fluid flowing out of the heat exchanger 20 can be effectively utilized to exchange heat with the heat of the exhaust gas from the compressor 10. This heat exchange can reduce the exhaust temperature, thereby increasing the diameter of the fluid flowing into the inlet 33 of the gas-liquid separator 30, which in turn facilitates the improvement of the gas-liquid separation efficiency of the gas-liquid separator 30, increases the recycling rate of the refrigeration oil, and reduces the accumulation of refrigeration oil in the heat exchanger 20, thereby improving the heat exchange efficiency and preventing compressor 10 failures caused by oil shortage. Secondly, by controlling the connection state between the outlet of the heat exchanger 20 and the inlet 33 of the gas-liquid separator 30, the oil return and heat exchange strategies can be optimized under different operating conditions, thereby improving the overall energy efficiency of the system. Furthermore, this configuration can also cool the high-temperature refrigerant discharged from the compressor 10, further improving the condensation effect. Therefore, the chiller system provided in this embodiment can solve the technical problem of low separation efficiency of refrigeration oil and refrigerant in existing chiller systems.

[0069] Specifically, the heat exchanger 20 is a shell-and-tube heat exchanger. The heat exchanger 20 has a first heat exchange section for containing refrigerant and a second heat exchange section for containing water.

[0070] Specifically, the chiller system also includes an air heat exchanger 130, with the first separation port 31 connected to it. The chiller system also includes an electronic expansion valve 140, with its inlet connected to the air heat exchanger 130 and its outlet connected to the heat exchanger 20. This structural arrangement, by connecting the first separation port 31 of the gas-liquid separator 30 to the air heat exchanger 130, allows for further cooling of the high-temperature, high-pressure refrigerant gas separated from the compressor 10 exhaust, reducing its temperature and improving condensation efficiency. The use of the electronic expansion valve 140 enables precise control of the refrigerant flow rate, automatically adjusting the refrigerant flow and pressure according to system load changes, thereby optimizing the energy efficiency ratio and operational stability of the refrigeration system.

[0071] Specifically, the refrigeration cycle of the chiller system includes: the high-temperature, high-pressure gas (carrying refrigerant oil) discharged from the compressor 10 enters the gas-liquid separator 30 through the inlet 33 for oil-gas separation, and most of the refrigerant oil is separated by the gas-liquid separator 30. The high-temperature, high-pressure refrigerant gas continues to enter the air heat exchanger 130 along the first separation port 31 for heat exchange, where it condenses into a high-pressure, medium-temperature refrigerant liquid. After being throttled and depressurized by the electronic expansion valve 140 (EXV), it enters the shell-and-tube heat exchanger, where it absorbs heat from the water, causing the water temperature to drop and thus producing chilled water. After absorbing heat and evaporating, the refrigerant enters the suction port 12 of the compressor 10, completing the refrigerant cycle.

[0072] Specifically, inlet 33 is connected to outlet 11 via exhaust pipe 150. At least a portion of the outlet of heat exchanger 20 is optionally connected to or disconnected from exhaust pipe 150. This structural arrangement allows for sufficient heat exchange between the cooling capacity of the fluid flowing out of heat exchanger 20 and the heat of the exhaust from compressor 10 within the exhaust pipe 150, utilizing its extended length. This further reduces the exhaust temperature, thereby increasing the diameter of the fluid flowing into inlet 33 of gas-liquid separator 30. This further facilitates improved gas-liquid separation efficiency of gas-liquid separator 30, increases the recycling rate of refrigeration oil, reduces the accumulation of refrigeration oil in heat exchanger 20, and thus improves heat exchange efficiency and prevents compressor 10 malfunctions due to oil shortage.

[0073] Specifically, the outlet portion of the heat exchanger 20 includes a first outlet 21 and a second outlet 22 spaced apart. The second outlet 22 is located below the first outlet 21. The first outlet 21 is connected to the compressor 10, and the second outlet 22 forms at least a portion of the outlet portion of the heat exchanger 20. This structural arrangement, by placing the second outlet 22 below the first outlet 21, facilitates the use of gravity to allow refrigerant containing refrigeration oil to preferentially flow out from the second outlet 22 for oil separation and return, thereby improving the efficiency of refrigeration oil recovery.

[0074] Specifically, the chiller system also includes a first valve body 40, which is disposed at least at a portion of the outlet of the heat exchanger 20. The first valve body 40 is used to control the connection or disconnection between at least a portion of the outlet of the heat exchanger 20 and the inlet 33. This structural arrangement provides flexibility in flow path control, enabling intelligent adjustment of the refrigerant flow distribution according to the system's operating status and requirements, avoiding unnecessary energy waste, and preventing liquid refrigerant from directly entering the compressor 10, thus reducing the risk of liquid compression.

[0075] Specifically, the chiller system also includes a pump body 50, which is located at least a portion of the outlet of the heat exchanger 20. The pump body 50 is used to direct the fluid flowing out of at least a portion of the outlet of the heat exchanger 20 into the inlet 33. With this structural arrangement, the use of the pump body 50 enhances the initiative of refrigerant oil recovery. By pumping the refrigerant mixture containing refrigerant oil into the inlet 33, the reliability of oil return is improved, while promoting the recycling of refrigerant.

[0076] Specifically, pump body 50 is a booster pump.

[0077] Specifically, the first valve body 40 and the pump body 50 open and close simultaneously. This synchronized start and stop of the first valve body 40 and the pump body 50 ensures that when oil-containing fluid needs to be drawn back from the heat exchanger 20, the pump body 50 immediately operates, while the first valve body 40 opens simultaneously, forming a continuous and reliable flow path. This allows the refrigerant oil in the heat exchanger 20 to be drawn back to the gas-liquid separator 30 in a timely and effective manner, preventing the accumulation of refrigerant oil in the heat exchanger 20, which would affect heat exchange efficiency. It also prevents the compressor 10 from experiencing poor lubrication due to insufficient oil, thus improving the system's operational stability and the reliability of the compressor 10.

[0078] Specifically, inlet 33 and outlet 11 are connected via outlet pipe 150. The chiller system also includes a pressure sensor 60, which is located at outlet pipe 150. This structural arrangement allows for real-time monitoring of the compressor 10's discharge pressure, facilitating timely adjustments to the system's operating status, optimizing condensation conditions, and providing data support for system protection and fault diagnosis. Furthermore, the pressure sensor 60, located at outlet pipe 150, can also monitor the pressure of the gas mixture between the compressor 10's discharge and the fluid flowing from the heat exchanger 20, thus enabling real-time monitoring of the system's status.

[0079] Specifically, the pressure detection range of the pressure detection element 60 is 0 kPa to 3550 kPa (inclusive of 0 kPa and 3550 kPa).

[0080] Specifically, inlet 33 and outlet 11 are connected via outlet pipe 150. The chiller system also includes a temperature sensor 70, which is located at outlet pipe 150. This structural arrangement allows the system to accurately monitor the temperature of the compressor 10's exhaust gas. This is crucial for optimizing refrigerant circulation, improving condensation efficiency, and preventing compressor 10 from overheating. It also provides ideal temperature control conditions for separating the refrigerant oil from the refrigerant. Furthermore, the temperature sensor 70, located at outlet pipe 150, can also monitor the temperature of the mixture between the compressor 10's exhaust gas and the fluid flowing from heat exchanger 20, facilitating real-time system monitoring.

[0081] Specifically, the temperature detection range of the temperature detection element 70 is 0℃~100℃ (inclusive of 0℃ and 100℃).

[0082] Specifically, inlet 33 and outlet 11 are connected via outlet pipe 150. The chiller system also includes a level sensor, which is installed inside the heat exchanger 20 to detect the refrigerant level within the heat exchanger 20. This structural arrangement allows for precise monitoring of refrigerant level changes within the heat exchanger 20, which is crucial for preventing refrigerant buildup, avoiding liquid compression by the compressor 10, and optimizing the refrigerant circulation path. Furthermore, the level information is a key basis for controlling the pump body 50 and the first valve body 40, contributing to improved overall system operating efficiency and safety.

[0083] In this embodiment, the gas-liquid separator 30 also has a second separation port 32, which is located below the first separation port 31 and is used to communicate with the compressor 10. The chiller system also includes an oil filter 120, which is located at the second separation port 32 and is used to filter impurities in the fluid discharged from the second separation port 32. With this structural arrangement, the design of the second separation port 32 makes full use of the principle of gravity to effectively separate the refrigerant oil in the condensed liquid, allowing it to flow preferentially through the second separation port 32, thereby improving the refrigerant oil return efficiency. The oil filter 120 can filter out impurities mixed in the condensed liquid, such as metal shavings and dust, preventing these impurities from entering the compressor 10, protecting the normal operation of the compressor 10, extending the system life, and ensuring the quality of the refrigerant oil, thereby optimizing the lubrication, cooling, and sealing effects of the compressor 10.

[0084] Specifically, the second separation port 32 is used to connect to the suction port 12 of the compressor 10 or the oil return port 13 of the compressor 10. This structural arrangement provides two options, increasing the flexibility of the system.

[0085] In this embodiment, the gas-liquid separator 30 also has a second separation port 32, which is located below the first separation port 31 and is used to communicate with the compressor 10. The chiller system also includes a second valve body 80, which is disposed at the second separation port 32 and is used to control the connection or disconnection between the second separation port 32 and the compressor 10. With this structural arrangement, the introduction of the second valve body 80 provides controllability of the flow path from the second separation port 32 to the compressor 10. It can intelligently adjust the refrigerant oil backflow according to the system operating status and demand, avoiding fluid backflow when not needed, reducing energy loss, and also preventing liquid refrigerant from entering the compressor 10 under inappropriate conditions, reducing the risk of liquid compression, and improving the safety and efficiency of system operation.

[0086] Specifically, the second valve body 80 opens and closes simultaneously with the compressor 10. This synchronized start and stop of the second valve body 80 and the compressor 10 ensures that when the compressor 10 starts, the second valve body 80 also opens simultaneously, allowing the refrigerant oil filtered at the second separation port 32 of the gas-liquid separator 30 to flow back to the compressor 10 in a timely manner. This ensures that the compressor 10 has sufficient refrigerant oil for lubrication, cooling, and sealing, preventing damage to the compressor 10 due to insufficient oil during startup. Simultaneously, when the compressor 10 shuts down, the second valve body 80 closes accordingly, preventing refrigerant or oil backflow, protecting the system from unnecessary pressure fluctuations and energy waste, and improving system safety and energy efficiency.

[0087] Specifically, the chiller system also includes an ejector 90, which is used to communicate with the suction port 12 of the compressor 10; the inlet of the ejector 90 can be selectively connected to or disconnected from the second outlet 22 of the heat exchanger 20, and the ejector port of the ejector 90 can be selectively connected to or disconnected from the exhaust port 11. The ejector 90 has an ejection state in which the inlet of the ejector 90 is connected to the second outlet 22, the ejector port of the ejector 90 is connected to the exhaust port 11, and the ejector 90 is connected to the suction port 12; and a closed state in which the inlet of the ejector 90 is disconnected from the second outlet 22 and the ejector port of the ejector 90 is disconnected from the exhaust port 11. With this structural design, the ejector 90 utilizes the kinetic energy and pressure difference of the compressor 10's exhaust to guide liquid containing refrigerant oil from the second outlet 22 of the heat exchanger 20 back to the compressor's suction port 12. This process requires no additional power source, saving energy and effectively solving the problem of refrigerant oil accumulation in the heat exchanger 20. This improves the refrigerant oil recovery rate and heat exchange efficiency, ensuring good lubrication and cooling conditions for the compressor 10, thereby enhancing the compressor's reliability. Secondly, this controllable connectivity allows the ejector 90 to switch between ejection and closed states under different operating conditions. In the ejection state, the inlet of the ejector 90 is connected to the second outlet 22, and the ejector port is connected to the exhaust port 11, achieving efficient refrigerant oil backflow. In the closed state, both the inlet and ejector port are disconnected, avoiding unnecessary fluid backflow, protecting the compressor from direct impact from liquid refrigerant, and reducing the risk of liquid compression. This intelligent flow path control optimizes the system's operating efficiency and safety under different operating conditions.

[0088] Specifically, the chiller system also includes a third valve body 100, which is located at the oil drain port of the heat exchanger 20. The third valve body 100 controls the connection or disconnection between the inlet of the ejector 90 and the second outlet 22 of the heat exchanger 20. This structural arrangement provides controllability to the flow path between the ejector 90 and the heat exchanger 20, enabling intelligent control of the oil-containing refrigerant fluid recovery process according to system requirements. When oil return is needed, the third valve body 100 opens, allowing the oil-containing fluid to smoothly enter the ejector 90, improving oil return efficiency. When the system does not need to recover refrigerant oil or is under abnormal operating conditions, the third valve body 100 closes to prevent unnecessary fluid flow, avoid energy consumption and system fluctuations, and ensure the safe operation of the equipment.

[0089] Specifically, the chiller system also includes a fourth valve body 110, which is located at the exhaust port 11. The fourth valve body 110 controls the connection or disconnection between the ejector port of the ejector 90 and the exhaust port 11. This fourth valve body 110 ensures flow path control between the ejector 90 and the exhaust port 11, allowing the ejector port to be opened or closed in a timely manner according to the compressor 10's operating status and system requirements. Utilizing the kinetic energy and pressure of the compressor 10's exhaust, it efficiently guides the oil-containing refrigerant in the heat exchanger 20 back to the compressor suction port 12, optimizing the refrigerant oil recovery path, reducing energy loss during the oil return process, and improving the overall system energy efficiency. Simultaneously, in non-oil return states or when the compressor 10 is not running, the fourth valve body 110 can be closed to avoid unnecessary fluid circulation in the system, protecting the compressor 10 from direct impact from liquid refrigerant, reducing the risk of liquid compression, and enhancing the system's operational safety and stability.

[0090] Specifically, the third valve body 100 and the fourth valve body 110 open and stop simultaneously. Specifically, the third valve body 100 and the fourth valve body 110 open periodically together. This structural arrangement, with the synchronized periodic operation of the third valve body 100 and the fourth valve body 110, automates and intelligently refrigerant oil recovery, enabling the refrigerant oil recovery process to be initiated periodically and automatically during system operation. This periodic opening strategy ensures timely recovery of refrigerant oil, preventing long-term accumulation in the heat exchanger 20, which affects heat exchange efficiency and normal equipment operation. Simultaneously, it avoids the energy waste and operational instability that might result from continuous oil return, ensuring efficient and stable system operation under various conditions. The periodic opening strategy can also be optimized and adjusted according to system operating conditions, further improving system energy efficiency and operational flexibility. Furthermore, this arrangement reduces the risk of liquid slugging. In conventional refrigeration systems, direct entry of liquid refrigerant into the compressor 10 can lead to liquid slugging, damaging the compressor 10. By establishing a controllable connection path, liquid carryover during suction can be avoided, thereby reducing the risk of liquid slugging and increasing system safety and operational stability.

[0091] Specifically, the first valve body 40, the second valve body 80, the third valve body 100, and the fourth valve body 110 are all solenoid valves.

[0092] Specifically, in order to avoid interfering with the communication between at least a portion of the outlet of the heat exchanger 20 and the inlet 33 of the gas-liquid separator 30, the third valve body 100 and the fourth valve body 110 are closed when the first valve body 40 is opened.

[0093] like Figure 2 As shown, Embodiment 2 of the present invention provides an oil return control method applicable to the chiller system provided in Embodiment 1. The oil return control method includes: obtaining at least one of the refrigerant quantity in the heat exchanger 20 of the chiller system and the exhaust temperature of the compressor 10 of the chiller system; and controlling the connection or disconnection between at least a portion of the outlet of the heat exchanger 20 and the inlet 33 of the gas-liquid separator of the chiller system based on at least one of the refrigerant quantity and exhaust temperature.

[0094] The oil return control method provided in Embodiment 2 of this invention can intelligently control the connection between the outlet of the heat exchanger 20 and the inlet 33 of the gas-liquid separator 30 based on the monitored refrigerant quantity and / or exhaust temperature, adjusting the oil return path and timing of the refrigeration oil. Thus, when the refrigerant quantity is sufficient and / or the exhaust temperature is high, the temperature of the high-temperature refrigerant discharged from the compressor 10 can be reduced using the relevant flow path, improving the condensation effect. Simultaneously, the cooling capacity of the fluid flowing out of the heat exchanger 20 can be effectively utilized to exchange heat with the heat of the compressor 10's exhaust. This heat exchange promotes a decrease in exhaust temperature, thereby increasing the diameter of the fluid flowing into the inlet 33 of the gas-liquid separator 30, which in turn facilitates improved gas-liquid separation efficiency of the gas-liquid separator 30, increases the recycling rate of the refrigeration oil, reduces the accumulation of refrigeration oil in the heat exchanger 20, thereby improving heat exchange efficiency and preventing compressor 10 malfunctions due to oil shortage, promoting refrigeration oil recovery, and preventing performance degradation of the compressor 10 due to oil shortage. When the refrigerant supply is insufficient or the exhaust temperature is low, priority is given to ensuring the system's refrigeration cycle to avoid affecting heat exchange within heat exchanger 20, thus ensuring efficient and safe system operation. The oil return control method can adjust the refrigerant oil recovery strategy according to different operating conditions, enhancing the system's adaptability to various operating conditions. This allows the chiller system to respond more flexibly to changing environments and demands, improving the overall system performance and operating efficiency. Therefore, the oil return control method provided in this embodiment can solve the technical problem of low refrigerant oil and refrigerant separation efficiency in existing chiller systems.

[0095] Specifically, the discharge temperature includes the discharge temperature of compressor 10. This allows for the determination of when to connect or disconnect at least a portion of the outlet of heat exchanger 20 with the inlet 33 of the chiller system based on the discharge temperature. Real-time monitoring of the compressor 10's discharge temperature enables accurate assessment of its heat load status and operating efficiency. High discharge temperatures are often associated with heat accumulation inside compressor 10 and decreased refrigerant circulation efficiency. By monitoring the discharge temperature, potential problems in system operation can be detected promptly, such as insufficient refrigerant or poor oil return. Corresponding control measures can then be taken to improve the oil return efficiency of the refrigerant oil, reduce the discharge temperature of compressor 10, prevent equipment failure caused by compressor overheating, and improve the operational safety and long-term reliability of the chiller system.

[0096] Specifically, the exhaust temperature includes the exhaust superheat of compressor 10. It should be noted that exhaust superheat is equal to the difference between the exhaust temperature and the saturation temperature corresponding to the exhaust pressure. With this setting, exhaust superheat directly affects the oil droplet diameter; the higher the exhaust superheat, the smaller the oil droplet diameter, and the lower the separation efficiency of the gas-liquid separator 30 for the refrigeration oil. Therefore, exhaust superheat is an important indicator for evaluating the refrigerant cycle efficiency and refrigeration oil recovery performance of compressor 10. Excessively high or low exhaust superheat can affect the stable operation of the system. By monitoring exhaust superheat, the system can intelligently determine the timing and amount of refrigeration oil recovery, ensuring that the refrigeration oil recovery process is initiated when the exhaust superheat reaches a threshold, effectively reducing exhaust superheat, preventing compressor 10 from overheating, and improving system operating efficiency. Simultaneously, the optimized exhaust superheat control strategy helps improve the lubrication conditions of compressor 10, increasing its reliability and service life.

[0097] Specifically, the refrigerant quantity includes the refrigerant level inside the heat exchanger 20. By adopting this setup, monitoring the refrigerant level inside the heat exchanger 20 allows for timely understanding of the refrigerant quantity in the system. This prevents at least a portion of the outlet of the heat exchanger 20 from connecting with the inlet 33 of the chiller system in the event of insufficient refrigerant in the heat exchanger 20, thereby affecting the normal refrigeration circulation path of the system.

[0098] Specifically, the method for controlling the connection or disconnection between at least a portion of the outlet of the heat exchanger 20 and the inlet 33 of the gas-liquid separator of the chiller system, based on at least one of the refrigerant quantity and exhaust temperature, includes: acquiring the refrigerant level in the heat exchanger 20, the exhaust temperature of the compressor 10, and the operating time of the compressor 10; determining whether the chiller system simultaneously meets a first preset judgment condition, a second preset judgment condition, a third preset judgment condition, and a fourth preset judgment condition; and, if the chiller system simultaneously meets the first, second, third, and fourth preset judgment conditions, controlling the connection between at least a portion of the outlet of the heat exchanger 20 and the inlet. The first preset judgment condition is that the exhaust temperature of the compressor 10 is greater than a preset temperature value; the second preset judgment condition is that the exhaust superheat of the compressor 10 is greater than a preset superheat value; the third preset judgment condition is that the refrigerant level in the heat exchanger 20 is greater than the first preset level value; and the fourth preset judgment condition is that the operating time of the compressor 10 is greater than a preset duration value. By adopting this setup, and through real-time acquisition of the refrigerant level in the heat exchanger 20, the exhaust temperature of the compressor 10, and its operating time, this control method can perform comprehensive analysis and decision-making based on multi-dimensional data, achieving precise control over the connection state between the outlet and inlet 33 of the heat exchanger 20. This real-time monitoring and intelligent decision-making capability improves the system's adaptability and response speed, ensuring efficient and stable operation under various working conditions. Specifically, the first preset judgment condition sets a threshold for the compressor 10's exhaust temperature. This allows the cooling effect of the fluid flowing out of the heat exchanger 20 to reduce the compressor 10's exhaust temperature when it is high, improving the compressor's reliability and service life. The second preset judgment condition focuses on the exhaust superheat. When the exhaust superheat exceeds a preset superheat, it indicates a decrease in the separation efficiency between the refrigerant oil and the refrigerant gas in the system. At this time, the refrigerant oil recovery process is initiated, effectively improving the recovery efficiency of refrigerant oil from the heat exchanger 20 to the compressor 10. This ensures sufficient refrigerant oil for lubrication and cooling inside the compressor 10, improving the operating efficiency and overall performance of the chiller system. The third preset judgment condition sets a threshold for the refrigerant level inside the heat exchanger 20. When the refrigerant level is higher than the first preset level value, the refrigerant oil recovery process is initiated. This avoids affecting the normal refrigeration cycle of the system due to excessively low refrigerant levels, optimizes the system's operating status, and improves system energy efficiency and equipment protection. The fourth preset judgment condition sets a threshold for the operating time of the compressor 10. Only when the operating time of the compressor 10 exceeds a preset time value will the system consider initiating the refrigerant oil recovery process. This avoids interference from system instability during the initial startup of the compressor 10, ensures that the oil return process starts when the system reaches a stable operating state, improves the efficiency and reliability of oil return, and reduces unnecessary energy consumption.By simultaneously meeting four preset judgment conditions to activate the connection between the outlet of heat exchanger 20 and the inlet 33, this control method realizes intelligent linkage between refrigerant oil recovery and system operation status. This not only improves the efficiency of refrigerant oil recovery and the operational safety of compressor 10, but also optimizes refrigerant circulation, improves the heat exchange efficiency of heat exchanger 20, reduces the overall energy consumption of the system, and enhances the overall performance and operational stability of the chiller system.

[0099] Specifically, the method for determining whether the chiller system meets the first preset judgment condition includes: acquiring the discharge temperature of compressor 10 within a first preset temperature measurement period; determining whether the discharge temperature of compressor 10 within the first preset temperature measurement period is greater than a preset temperature value; and determining that the chiller system meets the first preset judgment condition when the discharge temperature of compressor 10 within the first preset temperature measurement period is greater than the preset temperature value. Using this method, the judgment condition, by detecting the discharge temperature of compressor 10 within the first preset temperature measurement period, ensures that the system can respond and take action quickly when compressor 10 is under high heat load. If the discharge temperature remains higher than the preset temperature value within the set time period, the system will consider the first preset judgment condition met, thereby initiating the refrigerant oil recovery process. This utilizes the circulating cooling effect of the refrigerant oil to reduce the discharge temperature of compressor 10, preventing performance degradation and equipment failure caused by excessively high discharge temperature, and improving the operational stability and overall efficiency of compressor 10. This setting avoids the influence of unstable fluctuations in discharge temperature on the judgment of the first preset judgment condition.

[0100] Specifically, the method for determining whether the chiller system meets the second preset judgment condition includes: obtaining the discharge superheat of compressor 10 within a second preset temperature measurement period; determining whether the discharge superheat of compressor 10 within the second preset temperature measurement period is greater than a preset superheat; and determining that the chiller system meets the second preset judgment condition when the discharge superheat of compressor 10 is greater than the preset superheat within the second preset temperature measurement period. In this way, the second preset judgment condition, by monitoring the discharge superheat of compressor 10, ensures the optimization of refrigerant circulation and refrigeration oil separation efficiency. When the discharge superheat is continuously greater than the preset superheat within the second preset temperature measurement period, the system will consider the second preset judgment condition met and automatically initiate the refrigeration oil recovery process. High discharge superheat indicates a decrease in the separation efficiency of refrigeration oil and refrigerant in the system. By timely recovering refrigeration oil and optimizing the circulation path, the oil return rate of refrigeration oil can be improved, the lubrication conditions of compressor 10 can be improved, and the discharge superheat can be reduced, optimizing refrigerant circulation and improving the cooling efficiency and operational stability of the chiller system. This setting avoids the influence of unstable fluctuations in exhaust temperature and exhaust pressure on the judgment of the second preset judgment condition.

[0101] Specifically, the ratio of the first preset liquid level value to the height of the storage cavity of the heat exchanger 20 for storing refrigerant is greater than 0 and less than or equal to 0.3. This setting effectively controls the refrigerant level within the heat exchanger 20, preventing the heat exchanger 20 from connecting to the inlet 33 and affecting the normal refrigeration process if there is insufficient refrigerant. It also prevents poor oil return and reduced heat exchange efficiency due to excessively high liquid levels, while mitigating the risk of oil shortage in the compressor 10 due to excessively low liquid levels. This setting ensures a balance between refrigerant oil and refrigerant circulation under different operating conditions, optimizes the heat exchange efficiency of the heat exchanger 20, reduces the risk of liquid compression, and improves the overall performance and operational safety of the chiller system.

[0102] In this embodiment, the preset temperature value is greater than or equal to 60°C and less than or equal to 100°C. This allows the system to determine whether it is under high heat load by comparing the temperature with the preset value, triggering the refrigerant oil recovery process to reduce the discharge temperature of compressor 10 and prevent overheating that could lead to performance degradation or equipment failure. This intelligent control of the temperature threshold improves system operational stability and long-term reliability, while also optimizing the system's cooling efficiency and energy efficiency ratio.

[0103] In this embodiment, the preset superheat is greater than 0°C and less than or equal to 30°C. This allows the gas-liquid separator 30 to determine the separation efficiency of the refrigerant oil and refrigerant gas by comparing it with the preset superheat. This optimizes the circulation path of the refrigerant oil and refrigerant gas, increases the oil return rate, improves the lubrication of the compressor 10, reduces the exhaust superheat, optimizes refrigerant circulation, improves the cooling efficiency and overall performance of the chiller system, reduces equipment maintenance costs, and extends equipment lifespan.

[0104] In this embodiment, the preset duration is greater than or equal to 30 minutes. This ensures that the oil return process only starts after the compressor 10 reaches a stable operating state, avoiding energy waste and equipment shock caused by the system performing oil return operations during the initial startup or under unstable operating conditions.

[0105] Specifically, the oil return control method further includes: acquiring at least one of the following: refrigerant level in heat exchanger 20, discharge temperature of compressor 10, and operating status of compressor 10; determining whether the chiller system meets at least one of the fifth, sixth, and seventh preset judgment conditions; and, if the chiller system meets at least one of the fifth, sixth, and seventh preset judgment conditions, controlling at least a portion of the outlet of heat exchanger 20 to disconnect from the inlet 33; wherein the fifth preset judgment condition is that the discharge superheat of compressor 10 is less than or equal to a preset superheat; the sixth preset judgment condition is that the refrigerant level in heat exchanger 20 is less than a second preset level value; and the seventh preset judgment condition is that compressor 10 is in a closed state. With this setup, intelligent linkage between the refrigeration oil recovery process and the system operating status is achieved by real-time monitoring of the discharge superheat of compressor 10, the refrigerant level in heat exchanger 20, and the operating status of compressor 10. When one of the fifth, sixth, or seventh preset judgment conditions is met, the system can automatically adjust the connection state of the outlet of heat exchanger 20. This not only improves the efficiency of refrigerant oil recovery and optimizes the circulation and distribution of refrigerant oil, but also avoids potential risks in system operation, such as compressor 10 overheating, abnormal liquid level, and equipment failure, thereby improving the overall performance and operational safety of the chiller system. Specifically, regarding the fifth preset judgment condition, by acquiring the exhaust temperature of compressor 10 and detecting its exhaust superheat, if it is less than or equal to the preset superheat, the system will determine that the separation efficiency of the refrigerant oil and refrigerant gas has reached an optimal level, eliminating the need to initiate the refrigerant oil recovery process. This condition setting avoids unnecessary activation of the refrigerant oil recovery process, reducing system energy consumption and optimizing the circulation and distribution of refrigerant oil, maintaining efficient system operation with lower energy consumption, and improving the economy and reliability of the chiller system. Regarding the sixth preset judgment condition, by acquiring and monitoring the refrigerant level within the heat exchanger 20, when the level falls below the second preset level, the system will automatically disconnect the connection between the outlet and inlet 33 of the heat exchanger 20 to prevent the heat exchanger 20 from failing to produce chilled water due to excessively low refrigerant levels. This level control strategy not only avoids wear and performance degradation of the compressor 10 due to insufficient oil, but also ensures efficient heat exchange of the heat exchanger 20 and system energy efficiency, reduces the risk of hydraulic compression and equipment failure, and improves the operational safety and stability of the chiller system. Regarding the seventh preset judgment condition, by acquiring the operating status of the compressor 10, when the compressor 10 is in the off state, the system will automatically disconnect the connection between the outlet and inlet 33 of the heat exchanger 20.This state control strategy ensures that the refrigerant oil circulation and return process can be automatically stopped when the compressor 10 is not working, avoiding unnecessary energy consumption. At the same time, it reduces the maintenance complexity of the system in non-operational state, improves the energy efficiency and maintenance convenience of the chiller system, and reduces operating costs.

[0106] Specifically, the method for determining whether the chiller system meets the fifth preset judgment condition includes: obtaining the discharge superheat of compressor 10 within a third preset temperature measurement period; determining whether the discharge superheat of compressor 10 within the third preset temperature measurement period is consistently less than or equal to a preset superheat; and determining that the chiller system meets the fifth preset judgment condition when the discharge superheat of compressor 10 within the third preset temperature measurement period is consistently less than or equal to the preset superheat. This method, by obtaining the discharge superheat of compressor 10 within the third preset temperature measurement period and determining whether it is consistently less than or equal to the preset superheat, achieves refined monitoring of the system status. When the system meets the fifth preset judgment condition, it indicates that the separation efficiency of refrigerant oil and refrigerant gas in compressor 10 under the current operating conditions has reached an optimal level, eliminating the need for an additional refrigerant oil recovery process. Setting this condition avoids unnecessary refrigerant oil recovery operations, reduces system energy consumption, optimizes the refrigerant oil circulation path, ensures that compressor 10 operates under suitable exhaust superheat conditions, improves its operating efficiency and stability, and reduces the risk of equipment failure. It is a key technical means to achieve efficient and safe operation of the system.

[0107] Specifically, the first preset temperature measurement duration is greater than 0 seconds and less than or equal to 180 seconds. The second preset temperature measurement duration is greater than 0 seconds and less than or equal to 180 seconds. The third preset temperature measurement duration is 10 seconds. This avoids the influence of short-term fluctuations in the detection results on the judgment of the preset judgment conditions.

[0108] Specifically, the ratio of the second preset liquid level value to the height of the storage cavity of the heat exchanger 20 for storing refrigerant is greater than 0 and less than or equal to 0.3. This ensures that the refrigerant level inside the heat exchanger 20 is maintained at an appropriate level, avoiding oil shortage problems in the compressor 10 and insufficient refrigerant in the heat exchanger 20 caused by excessively low refrigerant levels. Simultaneously, this liquid level control strategy ensures sufficient space for refrigerant oil return, improves refrigerant oil recovery efficiency, optimizes refrigerant oil circulation and distribution, guarantees internal lubrication and cooling effects in the compressor 10, improves the heat exchange efficiency of the heat exchanger 20, reduces the risk of liquid compression, and optimizes refrigerant circulation. Therefore, it improves the overall performance and operational safety of the chiller system and is a key technical measure for achieving efficient and stable cooling.

[0109] As can be seen from the above description, the above embodiments of the present invention achieve the following technical effects: effectively reducing the amount of refrigeration oil accumulated in the cold water shell and pipe, lowering the exhaust temperature and reducing the amount of refrigeration oil entering the refrigerant circulation along with the refrigerant, and effectively reducing the risk of liquid carryover in the compressor suction.

[0110] 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.

[0111] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of this application. 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 drawings denote similar items; therefore, once an item is defined in one drawing, it need not be further discussed in subsequent drawings.

[0112] In the description of this application, 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 usually based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this application 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 application; the directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0113] 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.

[0114] 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 cannot be construed as limiting the scope of protection of this application.

[0115] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for controlling oil return in a chiller system, applicable to chiller systems, characterized in that, The chiller system includes: A compressor (10) and a heat exchanger (20), wherein the outlet of the heat exchanger (20) is connected to the compressor (10); A gas-liquid separator (30) is provided, the inlet (33) of which is connected to the exhaust port (11) of the compressor (10); the gas-liquid separator (30) has a first separation port (31) which is used to communicate with the inlet of the heat exchanger (20). At least a portion of the outlet of the heat exchanger (20) may be selectively connected to or disconnected from the inlet (33) so that when at least a portion of the outlet of the heat exchanger (20) is connected to the inlet (33), the fluid flowing out of at least a portion of the outlet of the heat exchanger (20) exchanges heat with the fluid discharged through the exhaust port (11). The oil return control method includes: Obtain at least one of the following: the amount of refrigerant in the heat exchanger of the chiller system and the discharge temperature of the compressor of the chiller system; Based on the refrigerant quantity and the exhaust temperature, control the connection or disconnection between at least a portion of the heat exchanger outlet and the inlet of the gas-liquid separator of the chiller system.

2. The method for controlling the oil return of a chiller system according to claim 1, characterized in that, The outlet portion of the heat exchanger (20) includes a first outlet (21) and a second outlet (22) spaced apart, the second outlet (22) being located below the first outlet (21). The first outlet (21) communicates with the compressor (10), and the second outlet (22) forms at least a portion of the outlet portion of the heat exchanger (20); and / or, The chiller system further includes a first valve body (40) disposed at at least a portion of the outlet of the heat exchanger (20), the first valve body (40) being used to control the connection or disconnection between at least a portion of the outlet of the heat exchanger (20) and the inlet (33); and / or, The chiller system also includes a pump body (50) disposed at at least a portion of the outlet of the heat exchanger (20), the pump body (50) being used to allow fluid flowing out at least a portion of the outlet of the heat exchanger (20) to enter the inlet (33).

3. The method for controlling the oil return of a chiller system according to claim 1, characterized in that, The inlet (33) and the outlet (11) are connected via an exhaust pipe (150); the chiller system also includes: A pressure sensing element (60) is provided at the exhaust pipe (150); and / or, A temperature sensing element (70) is disposed at the exhaust pipe (150); and / or, A liquid level detection element is installed inside the heat exchanger (20) and is used to detect the refrigerant level inside the heat exchanger (20).

4. The method for controlling the oil return of a chiller unit system according to claim 1, characterized in that, The gas-liquid separator (30) also has a second separation port (32), which is located below the first separation port (31) and is used to communicate with the compressor (10); the chiller system also includes: An oil filter (120) is disposed at the second separation port (32), the oil filter (120) being used to filter impurities in the fluid discharged from the second separation port (32); and / or, The second valve body (80) is located at the second separation port (32) and is used to control the connection or disconnection between the second separation port (32) and the compressor (10).

5. The method for controlling the oil return of a chiller unit system according to claim 1, characterized in that, The chiller system also includes: An ejector (90) is used to communicate with the suction port (12) of the compressor (10); the inlet of the ejector (90) may be connected or disconnected from the second outlet (22) of the heat exchanger (20), and the ejector port of the ejector (90) may be connected or disconnected from the exhaust port (11). The ejector (90) has an ejection state in which the inlet of the ejector (90) is connected to the second outlet (22), the ejector port of the ejector (90) is connected to the exhaust port (11), and the ejector (90) is connected to the intake port (12), and a closed state in which the inlet of the ejector (90) is disconnected from the second outlet (22) and the ejector port of the ejector (90) is disconnected from the exhaust port (11).

6. The oil return control method according to claim 1, characterized in that, The exhaust temperature information includes the exhaust temperature of the compressor; and / or, The exhaust temperature condition includes the exhaust superheat of the compressor; and / or, The refrigerant quantity information includes the refrigerant liquid level inside the heat exchanger.

7. The oil return control method according to claim 1, characterized in that, The step of controlling the connection or disconnection between at least a portion of the outlet of the heat exchanger and the inlet of the gas-liquid separator of the chiller system based on the refrigerant quantity and the exhaust temperature includes: The refrigerant level in the heat exchanger, the discharge temperature of the compressor, and the operating time of the compressor are obtained. Determine whether the chiller system simultaneously meets the first preset judgment condition, the second preset judgment condition, the third preset judgment condition, and the fourth preset judgment condition; When the chiller system simultaneously meets the first preset judgment condition, the second preset judgment condition, the third preset judgment condition, and the fourth preset judgment condition, at least a portion of the outlet of the heat exchanger is controlled to be connected to the inlet; The first preset judgment condition is that the exhaust temperature of the compressor is greater than a preset temperature value; the second preset judgment condition is that the exhaust superheat of the compressor is greater than a preset superheat value; the third preset judgment condition is that the refrigerant level in the heat exchanger is greater than a first preset level value; and the fourth preset judgment condition is that the running time of the compressor is greater than a preset duration value.

8. The oil return control method according to claim 7, characterized in that, The step of determining whether the chiller system meets the first preset judgment condition includes: acquiring the discharge temperature of the compressor within a first preset temperature measurement time range; determining whether the discharge temperature of the compressor within the first preset temperature measurement time range is greater than the preset temperature value; when the discharge temperature of the compressor within the first preset temperature measurement time range is greater than the preset temperature value, determining that the chiller system meets the first preset judgment condition; and / or, The step of determining whether the chiller system meets the second preset judgment condition includes: acquiring the discharge superheat of the compressor within a second preset temperature measurement time range; determining whether the discharge superheat of the compressor within the second preset temperature measurement time range is greater than the preset superheat; and determining that the chiller system meets the second preset judgment condition when the discharge superheat of the compressor within the second preset temperature measurement time range is greater than the preset superheat; and / or, The ratio of the first preset liquid level value to the height of the storage cavity of the heat exchanger for storing refrigerant is greater than 0 and less than or equal to 0.

3.

9. The oil return control method according to claim 7, characterized in that, The preset temperature value is greater than or equal to 60℃ and less than or equal to 100℃; and / or, The preset superheat is greater than 0°C and less than or equal to 30°C; and / or, The preset duration value is greater than or equal to 30 minutes.

10. The oil return control method according to claim 1, characterized in that, The oil return control method further includes: Obtain at least one of the following: refrigerant level in the heat exchanger, discharge temperature of the compressor, and operating status of the compressor; Determine whether the chiller system meets at least one of the fifth, sixth, and seventh preset judgment conditions; If the chiller system satisfies at least one of the fifth preset judgment condition, the sixth preset judgment condition, and the seventh preset judgment condition, at least a portion of the outlet of the heat exchanger is controlled to disconnect from the inlet; The fifth preset judgment condition is that the superheat of the compressor's exhaust is less than or equal to a preset superheat; the sixth preset judgment condition is that the refrigerant level in the heat exchanger is less than a second preset level value; and the seventh preset judgment condition is that the compressor is in a closed state.

11. The oil return control method according to claim 10, characterized in that, The step of determining whether the chiller system meets the fifth preset judgment condition includes: obtaining the discharge superheat of the compressor within a third preset temperature measurement time range; determining whether the discharge superheat of the compressor within the third preset temperature measurement time range is less than or equal to the preset superheat; when the discharge superheat of the compressor within the third preset temperature measurement time range is less than or equal to the preset superheat, determining that the chiller system meets the fifth preset judgment condition; and / or, The ratio of the second preset liquid level value to the height of the storage cavity of the heat exchanger for storing refrigerant is greater than 0 and less than or equal to 0.3.

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