Liquid level control method and water chiller refrigeration system

Abstract

The application provides a liquid level control method and a water chilling unit refrigeration system. The liquid level control method comprises the following steps: setting a target refrigerant liquid level in a condenser as H1, detecting an actual refrigerant liquid level in the condenser as H3; if H3 is greater than H1, increasing the opening degree of a first valve by a first set percentage and maintaining the first set time, so as to transport more refrigerant in the condenser to an economizer, thereby reducing the refrigerant liquid level in the condenser to H1. When the actual liquid level of the condenser is detected to be greater than the target liquid level, the opening degree of the first valve is increased, so that more refrigerant in the condenser flows into the economizer, thereby reducing the refrigerant liquid level in the condenser. Since more refrigerant in the water chilling unit refrigeration system flows into the economizer, the refrigerant input into the evaporator from the economizer is also increased, the amount of refrigerant in the evaporator is increased, thereby improving the refrigeration effect of the evaporator and improving the refrigeration efficiency of the unit.

Description

Technical Field

[0001] This invention relates to the field of refrigeration system technology, and more specifically, to a liquid level control method and a chiller unit refrigeration system. Background Technology

[0002] Centrifugal chillers are high-efficiency, energy-saving refrigeration equipment primarily used in air conditioning and refrigeration systems in commercial buildings and industrial production. Centrifugal chillers utilize a centrifugal compressor to increase the pressure and temperature of the refrigerant, then send the high-pressure refrigerant to the condenser for cooling and condensation. After condensation, the refrigerant passes through a throttling valve to reduce its pressure and temperature, becoming a low-temperature, low-pressure two-phase gas-liquid refrigerant. It then passes through an economizer into the evaporator to absorb heat, lowering the water temperature and achieving a cooling effect.

[0003] When a centrifugal chiller is operating, the refrigerant pressure in the condenser is higher than that in the evaporator. A sufficient pressure difference is required between the condenser and evaporator to ensure smooth refrigerant flow in the piping. At low pressure ratios (a lower pressure ratio between the condenser and evaporator), the refrigerant flow velocity in the piping is low and affected by flow resistance, easily leading to most of the refrigerant remaining in the condenser, resulting in less refrigerant entering the evaporator, affecting heat transfer and causing low unit efficiency. Current technology lacks regulation for situations where the refrigerant level in the condenser is too high, further impacting the cooling efficiency of the centrifugal chiller. Summary of the Invention

[0004] This invention provides a liquid level control method and a chiller refrigeration system to at least solve the problem in the prior art that centrifugal chillers lack the ability to regulate the refrigerant level in the condenser when it is too high, which affects the refrigeration efficiency of the unit.

[0005] To address the aforementioned problems, according to one aspect of the present invention, a liquid level control method is provided for a chiller unit refrigeration system. The liquid level control method includes a condenser liquid level control step, which includes:

[0006] S11. Set the target refrigerant level in the condenser to H1, and detect the actual refrigerant level in the condenser to H3.

[0007] S12. If H3 is greater than H1, the opening of the first valve is increased by a first set percentage and maintained for a first set time to deliver more refrigerant from the condenser to the economizer, thereby reducing the refrigerant level in the condenser to H1. The first set percentage is the percentage relative to the first valve being fully open.

[0008] Using the above method, when the actual liquid level in the condenser is detected to be higher than the target liquid level, the opening of the first valve is increased, allowing more refrigerant to flow into the economizer from the condenser, thereby reducing the refrigerant level in the condenser. Since more refrigerant flows into the economizer in the chiller unit's refrigeration system, more refrigerant is input into the evaporator from the economizer, increasing the amount of refrigerant in the evaporator, thereby improving the evaporator's cooling effect and increasing the unit's refrigeration efficiency.

[0009] Furthermore, the condenser level control steps also include:

[0010] S13. After the opening of the first valve increases by a first set percentage and is maintained for a first set time, if H3 is not greater than H1, the adjustment is stopped; if H3 is still greater than H1, S12 is repeated.

[0011] Furthermore, the condenser level control steps also include:

[0012] S14. After the opening of the first valve is adjusted to be fully open and maintained for the first set time, if H3 is still greater than H1, the branch valve is opened to directly deliver a portion of the refrigerant in the condenser to the evaporator without passing through the economizer, thereby reducing the refrigerant level in the condenser to H1.

[0013] Furthermore, the level control method includes an economizer level control step, which includes:

[0014] S21. Set the target refrigerant level in the economizer to H2, and detect the actual refrigerant level in the economizer to H4.

[0015] S22. If H4 is greater than H2, the opening of the second valve is increased by a second set percentage and maintained for a second set time to deliver more refrigerant from the economizer to the evaporator, thereby reducing the refrigerant level in the economizer to H2. The second set percentage is the percentage relative to the second valve being fully open.

[0016] Furthermore, the economizer level control steps also include:

[0017] S23. After increasing the opening of the second valve by the second set percentage and maintaining it for the second set time, if H4 is not greater than H2, then stop adjusting; if H4 is still greater than H2, then repeat S22.

[0018] Furthermore, the economizer level control steps also include:

[0019] S24. After the second valve is fully opened and maintained for the second set time, if H4 is still greater than H2, the third valve is closed to prevent the refrigerant in the economizer from flowing into the compressor's gas inlet. After the third valve is closed, the pressure in the economizer increases, and more refrigerant in the economizer is delivered to the evaporator, thereby reducing the refrigerant level in the economizer to H2.

[0020] Furthermore, the liquid level control method also includes:

[0021] Detect the refrigerant pressure P1 in the condenser and the refrigerant pressure P2 in the evaporator;

[0022] If P1 / P2 < 1.8, then execute the condenser level control step and the economizer level control step;

[0023] If P1 / P2≥1.8, then the condenser level control step and the economizer level control step will not be executed.

[0024] According to another aspect of the present invention, a chiller refrigeration system is provided, using the above-described liquid level control method. The chiller refrigeration system includes a compressor, a condenser, an economizer, and an evaporator connected in sequence to form a closed loop. A first liquid level gauge is provided on the condenser to detect the refrigerant level in the condenser. The outlet of the condenser is connected to the inlet of the economizer through a first pipeline. A first valve is provided on the first pipeline. The first valve is adjustable in opening and closing. The first valve is adjusted according to the detection result of the first liquid level gauge.

[0025] Furthermore, the outlet of the condenser is connected to the inlet of the evaporator through a regulating branch. A branch valve is installed on the regulating branch. The branch valve can be opened and closed and its opening degree is adjustable. The branch valve is adjusted according to the detection result of the first liquid level gauge.

[0026] Furthermore, the first valve and the branch valves are all electronic expansion valves. The chiller unit's refrigeration system also includes a controller. The first level gauge, the first valve, and the branch valves are all electrically connected to the controller. The controller controls the first valve and the branch valves respectively based on the detection result of the first level gauge.

[0027] Furthermore, a second level gauge is installed on the economizer to detect the refrigerant level inside the economizer. The first outlet of the economizer is connected to the inlet of the evaporator through a second pipeline. A second valve is installed on the second pipeline. The second valve is adjustable in opening and closing. The second valve is adjusted according to the detection result of the second level gauge.

[0028] Furthermore, the second outlet of the economizer is connected to the compressor's air supply port via a third pipeline. A third valve is installed on the third pipeline, which can be opened and closed and is adjusted according to the detection result of the second level gauge.

[0029] Furthermore, the second valve is an electronic expansion valve, the third valve is a butterfly valve, and the chiller unit's refrigeration system also includes a controller. The second level gauge, the second valve, and the third valve are all electrically connected to the controller. The controller controls the second valve and the third valve respectively based on the detection result of the second level gauge.

[0030] Furthermore, the chiller unit's refrigeration system also includes a first pressure sensor and a second pressure sensor. The first pressure sensor is used to detect the pressure inside the condenser, and the second pressure sensor is used to detect the pressure inside the evaporator.

[0031] Furthermore, the chiller unit's refrigeration system also includes a first temperature sensor, which is installed on the compressor to detect the temperature of the motor inside the compressor. The outlet of the condenser is connected to the compressor through a fourth pipeline, on which a fourth valve is installed. The fourth valve is adjustable in that it can be opened and closed.

[0032] Furthermore, the chiller unit's refrigeration system also includes a second temperature sensor and a frequency converter. The second temperature sensor is installed on the frequency converter to detect the temperature of the frequency converter. The outlet of the condenser is connected to the frequency converter through a fifth pipeline. A fifth valve is installed on the fifth pipeline. The fifth valve can be opened and closed and its opening degree is adjustable. Attached Figure Description

[0033] 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:

[0034] Figure 1 A schematic diagram of a liquid level control method provided by an embodiment of the present invention is shown;

[0035] Figure 2 A schematic diagram of the chiller refrigeration system provided in an embodiment of the present invention is shown.

[0036] The above figures include the following reference numerals:

[0037] 10. Compressor;

[0038] 20. Condenser;

[0039] 30. Economizer;

[0040] 40. Evaporator;

[0041] 51. First level gauge; 52. Second level gauge;

[0042] 61. First pipeline; 62. Regulating branch; 63. Second pipeline; 64. Third pipeline; 65. Fourth pipeline; 66. Fifth pipeline;

[0043] 71. First valve; 72. Branch valve; 73. Second valve; 74. Third valve; 75. Fourth valve; 76. Fifth valve;

[0044] 81. First temperature sensor; 82. Second temperature sensor;

[0045] 90. Frequency converter;

[0046] 100. Dryer. Detailed Implementation

[0047] 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. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0048] like Figure 1 As shown, an embodiment of the present invention provides a liquid level control method for a chiller unit refrigeration system. The liquid level control method includes a condenser liquid level control step, which includes:

[0049] S11. Set the target refrigerant level in the condenser 20 to H1, and detect the actual refrigerant level in the condenser 20 to H3.

[0050] S12. If H3 is greater than H1, the opening degree of the first valve 71 is increased by a first set percentage and maintained for a first set time to deliver more refrigerant from the condenser 20 to the economizer 30, thereby lowering the refrigerant level in the condenser 20 to H1. The first set percentage is the percentage relative to when the first valve 71 is fully open. The first set percentage and the first set time are set according to the system conditions; for example, the first set percentage is 10% to 20%, and the first set time is 2 to 4 minutes, such as 3 minutes.

[0051] Using the above method, when the actual liquid level in the condenser 20 is detected to be greater than the target liquid level, the opening of the first valve 71 is increased, allowing more refrigerant to flow into the economizer 30 from the condenser 20, thereby reducing the refrigerant level in the condenser 20. Since more refrigerant flows into the economizer 30 in the chiller unit's refrigeration system, the amount of refrigerant input from the economizer 30 to the evaporator 40 also increases, increasing the amount of refrigerant in the evaporator 40, thereby improving the cooling effect of the evaporator 40 and increasing the unit's refrigeration efficiency.

[0052] Furthermore, the condenser level control step also includes: S13, after the opening of the first valve 71 is increased by a first set percentage and maintained for a first set time, if H3 is not greater than H1, the adjustment is stopped; if H3 is still greater than H1, S12 is repeated.

[0053] If the liquid level in the condenser 20 does not drop to the target level after the opening of the first valve 71 is initially increased by the first set percentage and maintained for the first set time, more refrigerant can be output from the condenser 20 by continuing to increase the opening of the first valve 71, thereby achieving the purpose of lowering the liquid level and allowing more refrigerant to enter the evaporator 40.

[0054] In this method, the condenser level control step further includes: S14, after the opening of the first valve 71 is adjusted to be fully open and maintained for a first set time, if H3 is still greater than H1, then the branch valve 72 is opened to directly deliver a portion of the refrigerant in the condenser 20 to the evaporator 40 without passing through the economizer 30, thereby reducing the refrigerant level in the condenser 20 to H1.

[0055] If even with the first valve 71 adjusted to its maximum opening, the liquid level in the condenser 20 still cannot be lowered to the target liquid level H1, then the branch valve 72 is opened, allowing some refrigerant to bypass the economizer 30 and directly enter the evaporator 40 from the condenser 20. This reduces the refrigerant flow resistance, allowing more refrigerant to exit the condenser 20 and enter the evaporator 40, thereby lowering the liquid level in the condenser 20 to a suitable range.

[0056] Optionally, the condenser liquid level control step further includes: if H3 is greater than H1, opening the fourth valve 75, and through the fourth valve 75, inputting a portion of the refrigerant in the condenser 20 into the cooling channel inside the motor of the compressor 10 to cool the motor and prevent the motor temperature from becoming too high and affecting normal operation. This cools the motor while simultaneously lowering the liquid level in the condenser 20.

[0057] Optionally, the condenser liquid level control step further includes: if H3 is greater than H1, opening the fifth valve 76 to allow a portion of the refrigerant in the condenser 20 to be introduced into the cooling channel within the frequency converter 90 through the fifth valve 76 to cool the frequency converter 90 and prevent the frequency converter 90 from overheating and affecting normal operation. This cooling of the frequency converter 90 simultaneously lowers the liquid level within the condenser 20.

[0058] If the liquid level in the economizer 30 is too high during the operation of the chiller unit's refrigeration system, that is, if too much refrigerant remains in the economizer 30, it will also lead to a reduction in the amount of refrigerant entering the evaporator 40, thus affecting the system's refrigeration efficiency.

[0059] To address the issue of excessively high liquid level in the economizer 30, this liquid level control method includes economizer liquid level control steps, which include:

[0060] S21. Set the target refrigerant level in the economizer 30 to H2, and detect the actual refrigerant level in the economizer 30 as H4.

[0061] S22. If H4 is greater than H2, the opening of the second valve 73 is increased by a second set percentage and maintained for a second set time to deliver more refrigerant from the economizer 30 to the evaporator 40, thereby reducing the refrigerant level in the economizer 30 to H2. The second set percentage is the percentage relative to the second valve 73 being fully open.

[0062] The second set percentage and the second set time are set according to the system conditions. For example, the second set percentage is 10% to 20%, and the second set time is 2 to 4 minutes, such as 3 minutes.

[0063] Using the above method, when the actual liquid level of the economizer 30 is detected to be greater than the target liquid level, the opening of the second valve 73 is increased, allowing more refrigerant to flow into the evaporator 40, thereby reducing the refrigerant level in the economizer 30 and increasing the amount of refrigerant in the evaporator 40, so as to avoid affecting the cooling efficiency of the chiller unit's cooling system due to the excessively high liquid level of the economizer 30.

[0064] Furthermore, the economizer level control step also includes: S23, after increasing the opening of the second valve 73 by a second set percentage and maintaining it for a second set time, if H4 is not greater than H2, then stop the adjustment; if H4 is still greater than H2, then repeat S22.

[0065] If the liquid level in the economizer 30 does not drop to the target level after the opening of the second valve 73 is initially increased by the second set percentage and maintained for the second set time, more refrigerant in the economizer 30 can be output to the evaporator 40 by continuing to increase the opening of the second valve 73, thereby achieving the purpose of reducing the liquid level in the economizer 30.

[0066] In this scheme, the economizer level control step further includes: S24, after the opening of the second valve 73 is adjusted to be fully open and maintained for a second set time, if H4 is still greater than H2, the third valve 74 is closed to prevent the refrigerant in the economizer 30 from flowing into the gas supply port of the compressor 10. After the third valve 74 is closed, the pressure in the economizer 30 increases, and more refrigerant in the economizer 30 is delivered to the evaporator 40, thereby reducing the refrigerant level in the economizer 30 to H2.

[0067] With the third valve 74 closed, the economizer 30 is disconnected from the compressor 10, the pressure of the economizer 30 increases, and the pressure difference between the economizer 30 and the evaporator 40 increases. As a result, more refrigerant flows from the economizer 30 into the evaporator 40, thereby reducing the refrigerant level in the economizer 30.

[0068] Therefore, when the liquid level in the economizer 30 is too high and needs to be lowered, the liquid level is first adjusted by adjusting the opening of the second valve 73. If the liquid level in the economizer 30 cannot be lowered to a suitable range even when the opening of the second valve 73 is adjusted to the maximum, the liquid level in the economizer 30 can be further lowered by closing the third valve 74, thereby achieving the target liquid level.

[0069] In this scheme, the liquid level control method also includes: detecting the refrigerant pressure P1 in the condenser 20 and the refrigerant pressure P2 in the evaporator 40; if P1 / P2 < 1.8, then the condenser liquid level control step and the economizer liquid level control step are executed; if P1 / P2 ≥ 1.8, then the condenser liquid level control step and the economizer liquid level control step are not executed.

[0070] When P1 / P2 < 1.8, it is considered a low-pressure ratio operating condition. Under this condition, the refrigerant flow velocity in the pipeline is low and affected by flow resistance, which easily leads to most of the refrigerant remaining in the condenser 20 and economizer 30, resulting in less refrigerant entering the evaporator 40, affecting heat transfer and causing low unit efficiency. Therefore, under low-pressure ratio conditions, by executing the aforementioned condenser level control and economizer level control steps, the liquid levels in the condenser 20 and economizer 30 can be regulated to prevent them from exceeding the target levels. Under non-low-pressure ratio conditions, the liquid levels in the condenser 20 and economizer 30 typically do not exceed the target levels, so the condenser level control and economizer level control steps can be omitted.

[0071] This invention pre-sets two target liquid level heights, determines the relationship between the set target liquid level and the liquid level height detected by the two liquid level sensors, and adjusts the corresponding valves according to the determination results to achieve liquid regulation. The overall device structure of this invention is simple and can solve the problem of high refrigerant liquid level in the condenser 20 and economizer 30 when the chiller unit refrigeration system is running under low pressure ratio conditions, thereby improving the unit's energy efficiency.

[0072] like Figure 2 As shown, an embodiment of the present invention provides a chiller refrigeration system. Using the above-described liquid level control method, the chiller refrigeration system includes a compressor 10, a condenser 20, an economizer 30, and an evaporator 40 connected in sequence to form a closed loop. A first liquid level gauge 51 is installed on the condenser 20 to detect the refrigerant level inside the condenser 20. The outlet of the condenser 20 is connected to the inlet of the economizer 30 through a first pipe 61. A first valve 71 is installed on the first pipe 61. The first valve 71 is adjustable in opening and closing and its opening degree is adjustable. The first valve 71 is adjusted according to the detection result of the first liquid level gauge 51. The compressor 10 can be an air-suspended centrifugal compressor, a magnetic levitation centrifugal compressor, or other types of compressors.

[0073] In this design, the refrigerant circulates within the compressor 10, condenser 20, economizer 30, and evaporator 40, achieving cooling of the ambient space through the coordinated operation of multiple components. The refrigerant level in the condenser 20 can be detected by the first level gauge 51. If the detected refrigerant level in the condenser 20 is too high, affecting the unit's cooling efficiency, the refrigerant flow rate is changed by adjusting the opening of the first valve 71, thereby adjusting the refrigerant level in the condenser 20 to a suitable range.

[0074] That is, if the refrigerant level in the condenser 20 is detected to be too high, the opening of the first valve 71 can be increased to allow more refrigerant to flow from the condenser 20 into the economizer 30 through the first pipe 61, and then more refrigerant to flow into the evaporator 40, thereby reducing the refrigerant level in the condenser 20 and preventing the excessive refrigerant in the condenser 20 from affecting the cooling effect of the evaporator 40.

[0075] Furthermore, the outlet of the condenser 20 is connected to the inlet of the evaporator 40 via a regulating branch 62. A branch valve 72 is installed on the regulating branch 62, and the branch valve 72 is adjustable in opening and closing. The branch valve 72 is adjusted according to the detection result of the first level gauge 51. In this way, by opening the branch valve 72, a portion of the refrigerant in the condenser 20 can be directly introduced into the evaporator 40, increasing the level regulation capability within the condenser 20.

[0076] Specifically, branch valve 72 is normally closed. When the liquid level in condenser 20 is too high, the liquid level in condenser 20 is first adjusted by regulating the opening of the first valve 71. If adjusting the opening of the first valve 71 to its maximum still cannot lower the liquid level in condenser 20 to a suitable range, branch valve 72 can be opened in this case. This allows some refrigerant to bypass the economizer 30 and enter the evaporator 40 directly from condenser 20. This reduces refrigerant flow resistance, allowing more refrigerant to be discharged from condenser 20, thereby lowering the liquid level in condenser 20 to a suitable range.

[0077] like Figure 2 As shown, both the first valve 71 and the branch valve 72 are electronic expansion valves. The chiller unit's refrigeration system also includes a controller. The first level gauge 51, the first valve 71, and the branch valve 72 are all electrically connected to the controller. The controller controls the first valve 71 and the branch valve 72 respectively based on the detection result of the first level gauge 51. The first valve 71 and the branch valve 72 use electronic expansion valves and are controlled by the controller, which can achieve precise adjustment of the valve opening, thereby precisely adjusting the liquid level height of the condenser 20, and can realize automated operation.

[0078] like Figure 2 As shown, the economizer 30 is equipped with a second level gauge 52, which is used to detect the refrigerant level in the economizer 30. The first outlet of the economizer 30 is connected to the inlet of the evaporator 40 through a second pipe 63. A second valve 73 is installed on the second pipe 63. The second valve 73 can be opened and closed and its opening degree is adjustable. The second valve 73 is adjusted according to the detection result of the second level gauge 52.

[0079] The refrigerant level in the economizer 30 can be detected by the second level gauge 52. If the refrigerant level in the economizer 30 is too high and affects the cooling efficiency of the unit, the refrigerant flow rate can be changed by adjusting the opening of the second valve 73, thereby adjusting the refrigerant level in the economizer 30 to a suitable range.

[0080] That is, if the refrigerant level in the economizer 30 is detected to be too high, the opening of the second valve 73 can be increased to allow more refrigerant to flow from the economizer 30 into the evaporator 40 through the second pipe 63. This reduces the refrigerant level in the economizer 30 and increases the amount of refrigerant in the evaporator 40, thus preventing the refrigerant level in the evaporator 40 from being too low and affecting the cooling effect.

[0081] Furthermore, the second outlet of the economizer 30 is connected to the gas supply port of the compressor 10 via a third pipe 64. A third valve 74 is installed on the third pipe 64, which can be opened and closed and is adjusted according to the detection result of the second level gauge 52. The third valve 74 is normally open, and the third pipe 64 is used to supply gas to the compressor 10. When the third valve 74 is closed, the economizer 30 is disconnected from the compressor 10, the pressure in the economizer 30 increases, the pressure difference between the economizer 30 and the evaporator 40 increases, and more refrigerant flows from the economizer 30 into the evaporator 40, thereby lowering the refrigerant level in the economizer 30.

[0082] Therefore, when the liquid level in the economizer 30 is too high and needs to be lowered, the liquid level is first adjusted by regulating the opening of the second valve 73. If adjusting the second valve 73 to its maximum opening still cannot lower the liquid level in the economizer 30 to a suitable range, then the third valve 74 is closed to further lower the liquid level in the economizer 30. This configuration improves the liquid level regulation capability of the economizer 30.

[0083] Specifically, the second valve 73 is an electronic expansion valve, and the third valve 74 is a butterfly valve. The chiller unit's refrigeration system also includes a controller. The second level gauge 52, the second valve 73, and the third valve 74 are all electrically connected to the controller. The controller controls the second valve 73 and the third valve 74 respectively based on the detection result of the second level gauge 52. The second valve 73, as an electronic expansion valve, can achieve precise adjustment of its opening degree, while the third valve 74, as a butterfly valve, can achieve rapid opening and closing. Furthermore, by cooperating with the controller, automated operation can be achieved.

[0084] In this design, the chiller unit's refrigeration system also includes a first pressure sensor and a second pressure sensor. The first pressure sensor detects the pressure inside the condenser 20, and the second pressure sensor detects the pressure inside the evaporator 40. This allows for timely monitoring of the chiller unit's operating status through pressure detection. For example, by calculating the pressure ratio between the condenser 20 and the evaporator 40, it can be determined whether the chiller unit's refrigeration system is operating under a low-pressure ratio condition; for instance, a ratio less than 1.8 indicates a low-pressure ratio condition.

[0085] Under low-pressure conditions, less refrigerant flows into the evaporator 40, leaving more refrigerant in the condenser 20 and economizer 30. This results in higher liquid levels in the condenser 20 and economizer 30, affecting refrigeration efficiency. The liquid level needs particular attention under this condition and can be adjusted using the valves mentioned above.

[0086] Furthermore, the chiller unit refrigeration system also includes a first temperature sensor 81, which is installed on the compressor 10 to detect the temperature of the motor inside the compressor 10. The outlet of the condenser 20 is connected to the compressor 10 through a fourth pipe 65. A fourth valve 75 is installed on the fourth pipe 65, and the fourth valve 75 is set to be openable and adjustable.

[0087] The temperature of the motor inside the compressor 10 can be detected by the first temperature sensor 81. If the motor temperature is too high, it will affect the long-term reliable operation of the system. At this time, the fourth valve 75 can be opened to allow a portion of the refrigerant in the condenser 20 to be introduced into the cooling channel inside the motor through the fourth pipe 65 to cool the motor, thereby preventing the motor temperature from becoming too high. The refrigerant after heat exchange is then introduced into the evaporator 40 through the pipe.

[0088] Furthermore, under low pressure ratio conditions, the liquid level in the condenser 20 is relatively high. At this time, the fourth valve 75 can be opened to allow a portion of the refrigerant in the condenser 20 to be introduced into the cooling channel of the motor through the fourth pipe 65 to cool the motor. In this way, while cooling the motor, the liquid level in the condenser 20 is reduced.

[0089] like Figure 2 As shown, the chiller unit refrigeration system also includes a second temperature sensor 82 and a frequency converter 90. The frequency converter 90 is used to adjust the operating frequency of the compressor 10. The second temperature sensor 82 is installed on the frequency converter 90 to detect the temperature of the frequency converter 90. The outlet of the condenser 20 is connected to the frequency converter 90 through a fifth pipe 66. A fifth valve 76 is installed on the fifth pipe 66. The fifth valve 76 can be opened and closed and its opening degree is adjustable.

[0090] The temperature of the frequency converter 90 can be detected by the second temperature sensor 82. If the temperature of the frequency converter 90 is too high, it will affect the long-term reliable operation of the system. At this time, the fifth valve 76 can be opened to introduce a portion of the refrigerant in the condenser 20 into the cooling channel inside the frequency converter 90 through the fifth pipe 66 to cool the frequency converter 90, thereby preventing the frequency converter 90 from overheating. The refrigerant after heat exchange is then introduced into the evaporator 40 through the pipe.

[0091] Furthermore, under low pressure ratio conditions, the liquid level in the condenser 20 is relatively high. At this time, the fifth valve 76 can be opened to allow a portion of the refrigerant in the condenser 20 to be introduced into the cooling channel of the inverter 90 through the fifth pipe 66 to cool the inverter 90. In this way, while cooling the inverter 90, the liquid level in the condenser 20 is reduced.

[0092] In this design, the chiller unit's refrigeration system also includes a dryer 100, which is connected to the outlet of the condenser 20. If moisture enters the refrigeration system, it may alter the chemical properties of the refrigerant, affecting the refrigeration effect. Furthermore, moisture can freeze at low temperatures, potentially clogging pipes and impacting the system's operation. The dryer 100 effectively absorbs moisture from the refrigerant, maintaining stable operation of the refrigeration system. In addition to moisture, the refrigerant may also contain impurities such as oil and metal particles. These impurities also affect the refrigerant's performance and the system's operation. The dryer 100 adsorbs these impurities, ensuring the refrigerant's purity.

[0093] The above description is merely an optional embodiment of this solution and is not intended to limit the solution. Various modifications and variations can be made to this solution by those skilled in the art. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of this solution should be included within the scope of protection of this solution.

[0094] 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.

[0095] 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 invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the accompanying 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 exemplary only 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.

[0096] In the description of this solution, 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 attached drawings. It is only for the convenience of describing this solution and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or component referred to must have a specific orientation or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the scope of protection of this solution. The directional terms "inner" and "outer" refer to the inner and outer contours of each component itself.

[0097] 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.

[0098] 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 solution.

Claims

1. A liquid level control method for a chiller unit refrigeration system, characterized in that, The liquid level control method includes a condenser liquid level control step, which includes: S11. Set the target liquid level of refrigerant in the condenser (20) to H1, and detect the actual liquid level of refrigerant in the condenser (20) to H3; S12. If H3 is greater than H1, the opening of the first valve (71) is increased by a first set percentage and maintained for a first set time to deliver more refrigerant from the condenser (20) to the economizer (30), thereby reducing the refrigerant level in the condenser (20) to H1. The first set percentage is the percentage relative to the first valve (71) being fully open.

2. The liquid level control method according to claim 1, characterized in that, The condenser liquid level control step further includes: S13. After the opening of the first valve (71) is increased by the first set percentage and maintained for the first set time, if H3 is not greater than H1, the adjustment is stopped; if H3 is still greater than H1, S12 is repeated.

3. The liquid level control method according to claim 2, characterized in that, The condenser liquid level control step further includes: S14. After the opening of the first valve (71) is adjusted to be fully open and maintained for the first set time, if H3 is still greater than H1, the branch valve (72) is opened to directly deliver a portion of the refrigerant in the condenser (20) to the evaporator (40) without passing through the economizer (30), thereby reducing the refrigerant level in the condenser (20) to H1.

4. The liquid level control method according to claim 1, characterized in that, The liquid level control method includes an economizer liquid level control step, which includes: S21. Set the target refrigerant level in the economizer (30) to H2, and detect the actual refrigerant level in the economizer (30) to H4. S22. If H4 is greater than H2, the opening of the second valve (73) is increased by a second set percentage and maintained for a second set time to deliver more refrigerant from the economizer (30) to the evaporator (40), thereby reducing the refrigerant level in the economizer (30) to H2, wherein the second set percentage is the percentage relative to the second valve (73) being fully open.

5. The liquid level control method according to claim 4, characterized in that, The economizer level control step also includes: S23. After the opening of the second valve (73) is increased by the second set percentage and maintained for the second set time, if H4 is not greater than H2, the adjustment is stopped; if H4 is still greater than H2, S22 is repeated.

6. The liquid level control method according to claim 5, characterized in that, The economizer level control step also includes: S24. After the opening of the second valve (73) is adjusted to be fully open and maintained for the second set time, if H4 is still greater than H2, the third valve (74) is closed to prevent the refrigerant in the economizer (30) from flowing into the gas inlet of the compressor (10). After the third valve (74) is closed, the pressure in the economizer (30) increases, and more refrigerant in the economizer (30) is delivered to the evaporator (40), thereby reducing the refrigerant level in the economizer (30) to H2.

7. The liquid level control method according to claim 4, characterized in that, The liquid level control method further includes: The pressure P1 of the refrigerant in the condenser (20) and the pressure P2 of the refrigerant in the evaporator (40) are detected; If P1 / P2 < 1.8, then execute the condenser level control step and the economizer level control step; If P1 / P2 ≥ 1.8, then the condenser level control step and the economizer level control step will not be executed.

8. A chiller unit refrigeration system, characterized in that, Using the liquid level control method according to any one of claims 1 to 7, the chiller refrigeration system includes a compressor (10), a condenser (20), an economizer (30), and an evaporator (40) connected in sequence to form a closed loop. A first liquid level gauge (51) is provided on the condenser (20) for detecting the refrigerant level in the condenser (20). The outlet of the condenser (20) is connected to the inlet of the economizer (30) through a first pipe (61). A first valve (71) is provided on the first pipe (61). The first valve (71) is set to be openable and closable with an adjustable opening degree. The first valve (71) is adjusted according to the detection result of the first liquid level gauge (51).

9. The chiller refrigeration system according to claim 8, characterized in that, The outlet of the condenser (20) is connected to the inlet of the evaporator (40) through a regulating branch (62). A branch valve (72) is provided on the regulating branch (62). The branch valve (72) is set to be openable and closed and the opening degree is adjustable. The branch valve (72) is adjusted according to the detection result of the first level gauge (51).

10. The chiller unit refrigeration system according to claim 9, characterized in that, The first valve (71) and the branch valve (72) are both electronic expansion valves. The chiller refrigeration system also includes a controller. The first level gauge (51), the first valve (71), and the branch valve (72) are all electrically connected to the controller. The controller controls the first valve (71) and the branch valve (72) respectively according to the detection result of the first level gauge (51).

11. The chiller unit refrigeration system according to claim 8, characterized in that, The economizer (30) is equipped with a second level gauge (52), which is used to detect the refrigerant level in the economizer (30). The first outlet of the economizer (30) is connected to the inlet of the evaporator (40) through a second pipe (63). A second valve (73) is provided on the second pipe (63). The second valve (73) is adjustable and can be opened and closed. The second valve (73) is adjusted according to the detection result of the second level gauge (52).

12. The chiller refrigeration system according to claim 11, characterized in that, The second outlet of the economizer (30) is connected to the air supply port of the compressor (10) through a third pipeline (64). A third valve (74) is provided on the third pipeline (64). The third valve (74) can be opened and closed. The third valve (74) is adjusted according to the detection result of the second level gauge (52).

13. The chiller refrigeration system according to claim 12, characterized in that, The second valve (73) is an electronic expansion valve, and the third valve (74) is a butterfly valve. The chiller unit refrigeration system also includes a controller. The second level gauge (52), the second valve (73), and the third valve (74) are all electrically connected to the controller. The controller controls the second valve (73) and the third valve (74) respectively according to the detection result of the second level gauge (52).

14. The chiller refrigeration system according to claim 11, characterized in that, The chiller unit refrigeration system also includes a first pressure sensor and a second pressure sensor. The first pressure sensor is used to detect the pressure inside the condenser (20), and the second pressure sensor is used to detect the pressure inside the evaporator (40).

15. The chiller refrigeration system according to any one of claims 8 to 14, characterized in that, The chiller unit refrigeration system also includes a first temperature sensor (81), which is installed on the compressor (10) to detect the temperature of the motor inside the compressor (10). The outlet of the condenser (20) is connected to the compressor (10) through a fourth pipe (65). A fourth valve (75) is installed on the fourth pipe (65), and the fourth valve (75) is adjustable in that it can be opened and closed.

16. The chiller refrigeration system according to any one of claims 8 to 14, characterized in that, The chiller unit refrigeration system also includes a second temperature sensor (82) and a frequency converter (90). The second temperature sensor (82) is installed on the frequency converter (90) to detect the temperature of the frequency converter (90). The outlet of the condenser (20) is connected to the frequency converter (90) through a fifth pipeline (66). A fifth valve (76) is installed on the fifth pipeline (66). The fifth valve (76) is adjustable in that it can be opened and closed.

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