Air-cooled chiller and control method

Abstract

The present application relates to an air-cooled chiller and a control method, wherein the air-cooled chiller comprises a nuclear-grade motor and an open compressor connected to the nuclear-grade motor, wherein the open compressor is sequentially connected to an oil separator, a condensing system, a liquid reservoir, a throttling system and an evaporator through a refrigerant pipeline, and forms a refrigerant circulation loop, wherein an exhaust pressure sensor is arranged between the open compressor and the oil separator; the condensing system comprises multiple air-cooled condensing branches, each of which comprises a condenser, a two-speed fan and a pressure-discharging solenoid valve, the condensing inlet of the condenser is connected to the air outlet of the oil separator, a pressure-discharging solenoid valve is arranged on at least one first pipeline between the condensing inlet and the air outlet, the condensing outlet is connected to the liquid reservoir, the two-speed fan is arranged on the condenser, and the exhaust pressure sensor, the pressure-discharging solenoid valve and the two-speed fan are all electrically connected to the control unit. Through the present application, the problems of unstable high-pressure control and poor operation stability of the air-cooled chiller are solved.

Description

Technical Field

[0001] The invention relates to the field of nuclear power plant chillers, and in particular to an air-cooled chiller and a control method thereof. Background Art

[0002] Nuclear power is an economical, safe, reliable and clean new energy. The normal operation of a nuclear power plant requires appropriate ambient temperature and humidity. The "nuclear safety-grade air-cooled chiller" belongs to the electrical plant chilled water system. Its function is to provide the required chilled water for the DVC main control room air conditioning system, the DVL electrical plant main ventilation system, the DVE cable layer ventilation system, etc.

[0003] In order to increase the high pressure of the existing air-cooled chiller during winter cooling, a pressure maintaining valve is added to the condenser outlet to block the refrigerant from flowing from high pressure to low pressure through the pressure maintaining valve, thereby increasing the high pressure. However, when the ambient temperature of the air-cooled chiller is relatively low, the low pressure will drop rapidly when the air-cooled chiller is started, causing low pressure protection of the air-cooled chiller and the air-cooled chiller cannot operate stably, thus causing the electrical plant chilled water system to fail, and causing the temperature of the main control room, electrical plant, and cable layer of the electrical plant to rise, which will eventually lead to the shutdown of the nuclear power reactor of the power plant or other nuclear accidents.

[0004] At the same time, the control logic of the high-pressure control of the existing air-cooled chiller is chaotic, which makes the high-pressure pressure of the air-cooled chiller vary greatly, and the high and low pressure difference stability of the compressor and the operation stability of the air-cooled chiller are poor.

[0005] Currently, no effective solution has been proposed for the problems of unstable high-pressure control and poor operating stability of air-cooled chillers in related technologies. Summary of the invention

[0006] In this embodiment, an air-cooled chiller and a control method are provided to solve the problems of unstable high-pressure control and poor operating stability of the air-cooled chiller in the related art.

[0007] In the first aspect, an air-cooled chiller is provided in this embodiment, comprising a nuclear-grade motor and an open compressor connected to the nuclear-grade motor, wherein the open compressor is connected to an oil separator, a condensation system, a liquid reservoir, a throttling system and an evaporator in sequence through a refrigerant pipeline to form a refrigerant circulation loop, wherein an exhaust pressure sensor is provided on the refrigerant pipeline connecting the open compressor and the oil separator; the condensation system comprises a plurality of parallel air-cooled condensation branches, each of the air-cooled condensation branches comprises a condenser, a two-speed fan and a pressure-exhaust solenoid valve, the condenser comprises a condensation inlet and a condensation outlet, the condensation inlet is connected to the air outlet of the oil separator through a first pipeline, and the pressure-exhaust solenoid valve is provided on at least one of the first pipelines between the condensation inlet and the air outlet, the condensation outlet is connected to the liquid reservoir through a second pipeline, the two-speed fan is arranged on the condenser, and the exhaust pressure sensor, the pressure-exhaust solenoid valve and the two-speed fan are all electrically connected to a control unit.

[0008] In some embodiments, at least one of the second pipelines between the condensation outlet and the liquid storage tank is provided with a first one-way valve, wherein the first one-way valve is used to prevent the refrigerant from flowing back to the condenser.

[0009] In some embodiments, the condenser includes a finned heat exchanger.

[0010] In some of these embodiments, the evaporator comprises a nuclear-grade flooded evaporator.

[0011] In some of the embodiments, a filter is provided on the refrigerant pipeline between the liquid reservoir and the throttling system, wherein the filter is used to dry the refrigerant output along the liquid reservoir.

[0012] In some of the embodiments, an exhaust temperature sensor is also provided on the refrigerant pipeline between the open compressor and the oil separator, and an intake temperature sensor and an intake pressure sensor are provided on the refrigerant pipeline between the evaporator and the open compressor, wherein the exhaust temperature sensor, the intake temperature sensor and the intake pressure sensor are all electrically connected to the control unit.

[0013] In some of these embodiments, the throttling system includes an electronic expansion valve.

[0014] In some embodiments, an oil circuit for supplying oil to the open compressor is also provided between the oil separator and the open compressor, wherein the oil circuit includes an oil filter, the input end of the oil filter is connected to the oil outlet of the oil separator through an oil pipe, the output end of the oil filter is respectively connected to the input end of the first oil return branch and the input end of the second oil return branch, the output end of the first oil return branch is connected to the capacity regulating slide valve of the open compressor, and the output end of the second oil return branch is respectively connected to the suction and exhaust end bearings of the open compressor and the capacity regulating slide valve, wherein the first oil return branch is used to supply oil to the open compressor when the open compressor is started or the high and low pressure difference is less than a preset threshold value, and the second oil return branch is used to supply oil to the open compressor after the open compressor is started and / or when the high and low pressure difference is not less than a preset threshold value.

[0015] In some embodiments, the first oil return branch includes an oil pump and a check valve connected in series through the oil pipe, the input end of the oil pump is connected to the output end of the oil separator through the oil pipe, and the other end of the check valve is connected to the capacity adjustment slide valve through the oil pipe; the second oil return branch includes two second one-way valves arranged in parallel, one end of the two second one-way valves is connected to the output end of the oil filter through the oil pipe, and the other end of the two second one-way valves is respectively connected to the suction and exhaust end bearings of the open compressor and the capacity adjustment slide valve through the oil pipe.

[0016] In some embodiments, an oil pressure sensor is provided on the oil pipe between the capacity adjustment sliding valve and the check valve.

[0017] In a second aspect, a control method for an air-cooled chiller is provided in this embodiment. The air-cooled chiller includes the air-cooled chiller as described in the first aspect. The control method includes:

[0018] When the air-cooled chiller enters a high-pressure refrigeration operation state, the control unit acquires the exhaust pressure of the open compressor detected by the exhaust pressure sensor;

[0019] The control unit detects whether the exhaust pressure is in a preset exhaust pressure interval, and after first detecting that the exhaust pressure is in the preset exhaust pressure interval, controls a first device in one of the multiple air-cooled condensing branches to operate in a first working mode, wherein the first device includes a pressure discharge solenoid valve and one of a two-speed fan in one of the multiple air-cooled condensing branches, and the first working mode includes the corresponding pressure discharge solenoid valve being opened and the corresponding two-speed fan operating at a preset low speed;

[0020] After the first device operates in the first working mode, the control unit detects the exhaust pressure multiple times at a set time interval;

[0021] The control unit determines the pressure exhaust operation gear corresponding to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the pressure exhaust solenoid valve or the two-speed fan associated with the pressure exhaust operation gear to operate in a preset pressure exhaust mode, wherein each preset pressure exhaust mode sets the corresponding opening and closing state of the pressure exhaust solenoid valve and sets the corresponding wind speed gear of the two-speed fan.

[0022] In some embodiments, the control unit determines the exhaust pressure operation gear corresponding to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operation gear to operate in the preset exhaust pressure mode, including:

[0023] The control unit determines that the exhaust pressure operation gear includes a first gear when it is first determined that the exhaust pressure is in the preset exhaust pressure range after the first device is operated in the first working mode, wherein the first gear is associated with the first device in one of the multiple air-cooled condensing branches that is not operated in the first working mode;

[0024] The control unit controls the first device in one of the multiple air-cooled condensation branches that is not operating in the first working mode to operate in the preset exhaust pressure mode, and maintains the exhaust pressure in the preset exhaust pressure range.

[0025] In some embodiments, after the first device operates in the first operating mode, when the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, the control unit shuts down the first device operating in the first operating mode until the exhaust pressure increases to the preset exhaust pressure range.

[0026] In some embodiments, after the control unit controls the first device in one of the multiple air-cooled condensing branches that is not operating in the first working mode to operate in the preset exhaust pressure mode, the control unit determines the exhaust pressure operation gear corresponding to the judgment result based on the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operation gear to operate in the preset exhaust pressure mode, including:

[0027] When the control unit determines that the exhaust pressure is within the preset exhaust pressure range for multiple times in a row, the control unit controls the corresponding exhaust pressure solenoid valve or the two-speed fan to work in the preset exhaust pressure mode in sequence according to the preset exhaust pressure equipment operation order, until the control unit determines that the exhaust pressure is lower than the preset exhaust pressure range, and then shuts down the exhaust pressure solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode;

[0028] When the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, it shuts down the pressure exhaust solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode, and restarts the pressure exhaust solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode when it determines that the exhaust pressure is in the preset exhaust pressure range next time.

[0029] Compared with the related art, the air-cooled chiller and control method provided in the present embodiment, by arranging multiple parallel air-cooled condensing branches in the condensing system, each air-cooled condensing branch is provided with a condenser, a two-speed fan and a pressure exhaust solenoid valve, the condensation inlet of the condenser is connected to the air outlet of the oil separator through a first pipeline, and a pressure exhaust solenoid valve is provided on at least one first pipeline between the condensation inlet of the condenser and the air outlet of the oil separator, the condensation outlet of the condenser is connected to the liquid reservoir through a second pipeline, the two-speed fan is equipped with the condenser, the exhaust pressure sensor, the pressure exhaust solenoid valve and the two-speed fan are electrically connected to the control unit, thereby solving the problems of unstable high-pressure pressure control and poor operating stability of the air-cooled chiller in the related art, achieving stable control of the high-pressure pressure of the air-cooled chiller, stable high and low pressure difference of the open compressor, and stable operation of the air-cooled chiller.

[0030] Details of one or more embodiments of the present application are set forth in the following drawings and description to make other features, objects, and advantages of the present application more readily apparent. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] The drawings described herein are used to provide a further understanding of the present application and constitute a part of the present application. The illustrative embodiments of the present application and their descriptions are used to explain the present application and do not constitute an improper limitation on the present application. In the drawings:

[0032] Figure 1 is a structural schematic diagram of an air-cooled chiller according to an embodiment of the present application;

[0033] Figure 2 is a structural schematic diagram of an air-cooled chiller according to a preferred embodiment of the present application;

[0034] Figure 3 is a flow chart of a control method for an air-cooled chiller according to an embodiment of the present application;

[0035] Figure 4 is a flow chart of a control method for an air-cooled chiller according to a preferred embodiment of the present application;

[0036] Figure 5 It is a structural block diagram of a terminal of a control method for an air-cooled chiller according to an embodiment of the present application.

[0037] In the figure, 1. nuclear-grade motor; 2. open compressor; 3. oil separator; 4. two-speed fan; 5. condenser; 6. liquid storage tank; 7. filter; 8. throttling system; 9. evaporator; 10. oil filter; 11. oil pump; 12. check valve; 13. oil pressure sensor; 14. exhaust temperature sensor; 15. exhaust pressure sensor; 16. suction temperature sensor; 17. suction pressure sensor; 18. exhaust pressure solenoid valve; 19. first one-way valve. DETAILED DESCRIPTION

[0038] In order to more clearly understand the purpose, technical solutions and advantages of the present application, the present application is described and illustrated below in conjunction with the accompanying drawings and embodiments.

[0039] Unless otherwise defined, the technical terms or scientific terms involved in this application shall have the general meaning understood by people with ordinary skills in the technical field to which this application belongs. The words "one", "a", "a", "the", "these" and the like in this application do not represent quantitative restrictions, and they can be singular or plural. The terms "include", "comprise", "have" and any variants thereof involved in this application are intended to cover non-exclusive inclusions; for example, a process, method and system, product or device comprising a series of steps or modules (units) is not limited to the listed steps or modules (units), but may include unlisted steps or modules (units), or may include other steps or modules (units) inherent to these processes, methods, products or devices. The words "connect", "connected", "coupled" and the like involved in this application are not limited to physical or mechanical connections, but may include electrical connections, whether directly or indirectly. The "multiple" involved in this application refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there can be three relationships. For example, "A and / or B" can mean: A exists alone, A and B exist at the same time, and B exists alone. Usually, the character " / " indicates that the objects associated with each other are in an "or" relationship. The terms "first", "second", "third", etc. involved in this application are only used to distinguish similar objects and do not represent a specific ordering of the objects.

[0040] Figure 1The schematic diagram of the structure of the air-cooled chiller in the embodiment of the present application. The air-cooled chiller shown in the figure solves the problems of unstable high-pressure control and poor operation stability of the air-cooled chiller by setting a multi-way air-cooled condensation branch composed of a condenser 5, a two-speed fan 4 and a pressure exhaust solenoid valve 18 in parallel, based on the exhaust pressure as the control target, and realizes the stable control of the high-pressure pressure of the air-cooled chiller, the high and low pressure difference of the open compressor is stable, and the air-cooled chiller operates stably.

[0041] See also Figure 1 to Figure 2 The embodiment of the present application provides an air-cooled chiller, comprising a nuclear-grade motor 1, an open compressor 2 connected to the nuclear-grade motor 1, the open compressor 2 is connected to the oil separator 3, the condensation system, the liquid reservoir 6, the throttling system 8 and the evaporator 9 in sequence through a refrigerant pipeline, and forms a refrigerant circulation loop, wherein an exhaust pressure sensor 15 is provided on the refrigerant pipeline connecting the open compressor 2 and the oil separator 3; the condensation system comprises a plurality of parallel air-cooled condensation branches, each of which comprises a condenser 5, a two-speed fan 4 and a pressure-discharging solenoid valve 18, the condenser 5 comprises a condensation inlet and a condensation outlet, the condensation inlet is connected to the air outlet of the oil separator 3 through a first pipeline, and a pressure-discharging solenoid valve 18 is provided on at least one first pipeline between the condensation inlet and the air outlet, the condensation outlet is connected to the liquid reservoir 6 through a second pipeline, the two-speed fan 4 is arranged on the condenser 5, and the exhaust pressure sensor 15, the pressure-discharging solenoid valve 18 and the two-speed fan 4 are all electrically connected to a control unit (not shown in the drawings).

[0042] In the above-mentioned air-cooled chiller, a multi-way air-cooled condensing branch consisting of a condenser 5, a two-speed fan 4 and a pressure relief solenoid valve 18 is set in parallel, and the exhaust pressure is used as the control target to solve the problems of unstable high-pressure pressure control and poor operating stability of the air-cooled chiller, thereby ensuring that the nuclear-grade air-cooled chiller can achieve stable refrigeration operation in winter and avoid low-pressure protection; at the same time, a pressure relief solenoid valve 18 is set at the condensation inlet of the condenser 5 to avoid the migration of refrigerant to the condenser 5 in winter, which may cause low-pressure protection when the air-cooled chiller is started and cause failure of the air-cooled chiller.

[0043] It should be noted that, in the present embodiment, the control unit detects whether the exhaust pressure is in the preset exhaust pressure range by comparing the exhaust pressure at the output end of the open compressor 2 obtained by the exhaust pressure sensor 15 with the preset exhaust pressure range, thereby correspondingly controlling the start and stop of the exhaust pressure solenoid valve 18 and / or the two-speed fan 4. Specifically, when it is detected that the exhaust pressure is in the preset exhaust pressure range, especially when the upper limit of the preset exhaust pressure range is reached, if the existing refrigerant circulation loop is maintained at this time, the exhaust pressure of the open compressor 2 will increase and exceed the preset exhaust pressure range. At this time, by opening The exhaust pressure solenoid valve 18 keeps the condenser 5 in an open state, thereby increasing the heat exchange between the air-cooled chiller and the outside and reducing the pressure of the air-cooled chiller until the exhaust pressure returns to the preset exhaust pressure range, and / or by turning on the two-speed fan 4 and running the two-speed fan 4 at an appropriate wind speed gear to accelerate the heat exchange of the condenser 5, thereby reducing the exhaust pressure of the air-cooled chiller; when it is detected that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, if the corresponding refrigerant circulation loop is maintained at this time, that is, the corresponding two-speed fan 4 is continued to operate or the exhaust pressure solenoid valve 18 is opened, the open compressor 2 is getting lower and lower, causing the air-cooled chiller to perform low-pressure protection or malfunction. At this time, the exhaust pressure solenoid valve 18 is closed to put the condenser 5 in a closed state, thereby reducing the heat exchange between the air-cooled chiller and the outside, and increasing the pressure of the air-cooled chiller until the exhaust pressure is increased to a preset exhaust pressure range, and / or by reducing the wind speed of the two-speed fan 4 or turning off the two-speed fan 4, reducing the heat exchange of the condenser 5, thereby increasing the exhaust pressure of the air-cooled chiller; of course, the gear position of the two-speed fan 4 can be set according to the need to reduce the exhaust pressure or increase the exhaust pressure. In this embodiment, The two-speed fan 4 is set with two wind speed gears, namely: low speed gear and high speed gear. In the process of graded control of high pressure pressure in this embodiment, the two-speed fan 4 will be operated at low speed first. When the two-speed fan 4 is not enough to reduce the exhaust pressure of the open compressor 2 to the preset exhaust pressure range when it is operated at low speed, the two-speed fan 4 will be operated at high speed, so that the exhaust pressure of the open compressor 2 is reduced to the preset exhaust pressure range, so that the high pressure pressure of the air-cooled chiller is maintained stable and a stable high and low pressure difference is established. Otherwise, the wind speed gear of the two-speed fan 4 is first reduced until the two-speed fan 4 is turned off.

[0044] It should be noted that, in the present embodiment, during the high-pressure pressure control process, the control unit controls the start-up of the pressure relief solenoid valve 18 and the two-speed fan 4 of the corresponding air-cooled condensing branch according to the preset pressure relief equipment operation order. For example, it is set to first make the two-speed fan 4 of a certain air-cooled condensing branch run at a low speed, and then open at least one pressure relief solenoid valve 18 of the air-cooled condensing branch, and then make the two-speed fan 4 run at a high speed; at the same time, in the present embodiment, according to the needs of high-pressure pressure control, different numbers of air-cooled condensing branches are set, for example, two parallel air-cooled condensing branches are set (reference Figure 1 and Figure 2 ), and are arranged symmetrically on the left and right, and according to the different number of grade adjustment gears, different numbers of pressure relief solenoid valves 18 are arranged in each air-cooled condensing branch. For example, one pressure relief solenoid valve 18 is arranged in one air-cooled condensing branch (refer to Figure 1 ), thus, two air-cooling condensation branches are combined to form six-speed adjustment gears. For example, two pressure relief solenoid valves 18 are set in one air-cooling condensation branch (refer to Figure 2 ), thus, in combination with setting two air-cooled condensation branches, eight adjustment gears are formed; of course, in order to make the high-pressure pressure control more stable, more adjustment gears can be set; when further explanation is needed, each adjustment gear of the constructed multiple adjustment gears corresponds to the preset operation order of the pressure relief equipment, for example: when six adjustment gears are formed by setting two air-cooled condensation branches and setting a pressure relief solenoid valve 18 for each air-cooled condensation branch, the preset operation order of the pressure relief equipment from the first gear to the sixth gear is: Figure 1 The two-speed fan 4 on the left side runs at low speed. Figure 1 The pressure relief solenoid valve 18 on the left side is opened. Figure 1 The pressure relief solenoid valve 18 on the right side is opened. Figure 1 The two-speed fan 4 on the left side runs at high speed. Figure 1 The two-speed fan 4 on the right side runs at low speed and Figure 1 The two-speed fan 4 located on the right side in the middle runs at a high speed.

[0045] In order to prevent the refrigerant from migrating to the condenser 5 during the winter refrigeration process, causing low-pressure protection when the air-cooled chiller is started, in some embodiments, at least one second pipeline between the condensation outlet and the liquid reservoir 6 is provided with a first one-way valve 19, wherein the first one-way valve 19 is used to prevent the refrigerant from flowing back to the condenser 5.

[0046] It should be understood that, with such an arrangement, the one-way conduction function of the first one-way valve 19 allows the refrigerant to flow only in the direction from the condenser 5 to the liquid storage tank 6, thereby avoiding the refrigerant backflow and causing a refrigerant circulation backflow failure.

[0047] In order to improve the heat exchange efficiency of the air-cooled condensation branch, in some embodiments, the condenser 5 includes a finned heat exchanger.

[0048] It should be noted that, in this embodiment, the condenser 5 includes but is not limited to a finned heat exchanger, and any air-cooled condenser that meets the requirements of this embodiment is suitable for the condenser 5 in this application.

[0049] In order to achieve full contact between the refrigerant and the heat transfer surface and improve the boiling heat transfer coefficient, in some embodiments, the evaporator 9 includes a nuclear-grade flooded evaporator.

[0050] In order to remove the water vapor generated during the heat exchange process of the refrigerant output along the condensing system, in some embodiments, a filter 7 is provided on the refrigerant pipeline between the liquid reservoir 6 and the throttling system 8, wherein the filter 7 is used to dry the refrigerant output along the liquid reservoir 6.

[0051] In this embodiment, the liquid reservoir 6 adopts a large-capacity nuclear-grade liquid reservoir to carry excess refrigerant of the air-cooled chiller in a wide cooling range of ambient temperature from -15°C to 45°C, ensuring stable and reliable operation of the air-cooled chiller under variable operating conditions.

[0052] In order to ensure that the intake and exhaust of the open compressor 2 can work normally, in some embodiments, an exhaust temperature sensor 14 is also provided on the refrigerant pipeline between the open compressor 2 and the oil separator 3, and an intake temperature sensor 16 and an intake pressure sensor 17 are provided on the refrigerant pipeline between the evaporator 9 and the open compressor 2, wherein the exhaust temperature sensor 14, the intake temperature sensor 16 and the intake pressure sensor 17 are all electrically connected to the control unit.

[0053] In this embodiment, the suction pressure sensor 17 is used to detect the suction pressure at the suction end of the open compressor, and the pressure difference with the exhaust pressure at the exhaust end of the open compressor 2 detected by the exhaust pressure sensor 15 is used to construct the high and low pressures of the air-cooled chiller.

[0054] It should be understood that an exhaust temperature sensor 14 and an exhaust pressure sensor 15 are provided on the refrigerant pipeline between the open compressor 2 and the oil separator 3, and the air-cooled chiller calculates the exhaust superheat by the changes in temperature and pressure in the refrigerant circulation loop, and controls the opening size of the throttling system 8 by comparing it with the target exhaust superheat; similarly, by providing an intake temperature sensor 16 and an intake pressure sensor 17 on the refrigerant pipeline between the open compressor 2 and the evaporator 9, the air-cooled chiller calculates the intake superheat by the changes in temperature and pressure in the refrigerant circulation loop, and controls the opening size of the throttling system 8 by comparing it with the target intake superheat, and the air-cooled chiller calculates the exhaust superheat, the intake superheat and controls the opening size of the throttling system 8 based on the changes in temperature and pressure in the refrigerant circulation loop through the control unit.

[0055] In order to achieve accurate control of the refrigerant flow rate and the liquid level of the evaporator 9, in some embodiments, the throttling system 8 includes an electronic expansion valve.

[0056] It should be understood that the throttling system 8 uses an electronic expansion valve, which can achieve precise control of the refrigerant flow and the liquid level of the evaporator 9, leaving a large margin in the selection of cooling capacity to ensure stable operation under two extreme conditions of cooling water inlet temperature of 15 to 45 degrees.

[0057] In order to realize the normal operation of the open compressor of the air-cooled chiller and overcome the problem of oil return difficulty of the compressor, in some embodiments, an oil circuit for supplying oil to the open compressor 2 is also provided between the oil separator 3 and the open compressor 2, wherein the oil circuit includes an oil filter 10, the input end of the oil filter 10 is connected to the oil outlet of the oil separator 3 through an oil pipe, the output end of the oil filter 10 is respectively connected to the input end of the first oil return branch and the input end of the second oil return branch, the output end of the first oil return branch is connected to the capacity regulating slide valve of the open compressor 2, and the output end of the second oil return branch is respectively connected to the suction and exhaust end bearings and the capacity regulating slide valve of the open compressor 2, wherein the first oil return branch is used to supply oil to the open compressor 2 when the open compressor 2 is started or the high and low pressure difference is less than a preset threshold value, and the second oil return branch is used to supply oil to the open compressor 2 after the open compressor 2 is started and / or when the high and low pressure difference is not less than a preset threshold value.

[0058] In this embodiment, the first oil return branch includes an oil pump 11 and a check valve 12 connected in series through an oil pipe, the input end of the oil pump 11 is connected to the output end of the oil separator 3 through the oil pipe, and the other end of the check valve 12 is connected to the capacity adjustment slide valve through the oil pipe; the second oil return branch includes two second one-way valves arranged in parallel, one end of the two second one-way valves is connected to the output end of the oil filter 10 through an oil pipe, and the other end of the two second one-way valves is respectively connected to the suction and exhaust end bearings and the capacity adjustment slide valve of the open compressor 2 through the oil pipe.

[0059] In this embodiment, an oil pressure sensor 13 is provided on the oil pipe between the capacity adjustment sliding valve and the check valve 12 , wherein the oil pressure sensor 13 is used to detect the oil supply pressure measurement of the open compressor 2 .

[0060] It should be noted that, in the present embodiment, the oil circuit of the open compressor 2 controlled by the rear end of the oil filter 10 is divided into two branches, the first oil return branch is connected to the capacity regulating slide valve through the oil pump 11 and the check valve 12, and the second oil return branch is directly connected to the inner bearing and the capacity regulating slide valve of the open compressor 2 through the oil pipe and two second one-way valves. Before the open compressor 2 is started, the oil pump 11 is driven first, that is, the oil pressure is established by the oil pump 11, so as to supply oil and lubricate the bearings, shaft seals and compression chambers at the suction and exhaust ends of the open compressor 2, and push the capacity regulating slide valve to the minimum load to reduce the starting current of the open compressor 2, and monitor the oil supply of the oil pump 11 after a short delay. The oil supply pressure (measured by the oil pressure sensor 13) and the compressed exhaust pressure (measured by the exhaust pressure sensor 15), if the corresponding oil supply pressure or exhaust pressure exceeds a certain value, the open compressor 2 is started. After the open compressor 2 runs for a certain period of time, the difference between the oil supply pressure and the suction pressure (measured by the suction pressure sensor 17) is calculated. If the pressure difference does not reach the target value at this time, it will be shut down. If it reaches the target value, the open compressor 2 will continue to run. After that, the working state of the oil pump 11 is controlled according to the pressure difference between the suction pressure and the exhaust pressure. If the difference between the exhaust pressure and the suction pressure is less than the limit value, the oil pump 11 is turned on, otherwise the oil pump 11 is turned off. When the oil pump 11 is turned off, the oil does not pass through the oil pump 11 at this time, but directly flows to the open compressor 2 from the second oil return branch. The pressure difference established by the normal operation of the open compressor 2 is used to push the lubricating oil for lubrication, ensuring the normal operation of the air-cooled chiller under various working conditions.

[0061] It should be further explained that the open compressor 2 adopts differential pressure oil supply, and the control unit detects the high and low pressure difference between the suction pressure and the exhaust pressure to drive the suction and exhaust end bearings of the open compressor to lubricate the refrigeration oil, and at the same time cools and seals the compression chamber and the rotor, and pushes the capacity adjustment slide valve to perform loading and unloading actions. When the ambient temperature is too low, the exhaust pressure and the exhaust temperature are too low. At this time, the high and low pressure difference is too small, and it is difficult to maintain the refrigeration oil flow required for the normal operation of the open compressor 2. Due to the low exhaust temperature, the viscosity of the refrigeration oil is large and the flow resistance is high; at the same time, under this working condition, the refrigerant flow and performance of the throttling system 8 will be severely attenuated, and the liquid level and evaporation pressure of the evaporator 9 will also be too low. At this time, it is automatically started by the oil pump 11; on the cooling water side of the evaporator 9, the high pressure is kept above the minimum limit through the control of the exhaust pressure solenoid valve 18 and the two-speed fan 4 of the air-cooled condensation branch to maintain the normal oil supply of the oil circuit.

[0062] The working process of the air-cooled chiller is described as follows:

[0063] When the nuclear-grade motor 1 adopts a 1E-grade motor, the open compressor 2 is driven and operated by the nuclear-grade motor 1. After the refrigerant is compressed and discharged in the open compressor 2, it enters the external oil separator 3. The lubricating oil is separated by a combination of changing the gas flow direction, reducing the gas flow rate, and mechanical separation. The separated lubricating oil passes through the oil filter 10 and is sprayed back to the suction side of the open compressor 2 along the first return oil branch or the second return oil branch to cool, seal and lubricate the suction and exhaust end bearings, compression chamber and rotor of the open compressor 2, and pushes the capacity adjustment slide valve to add and unload the capacity. The refrigerant gas enters the condensation system for condensation, and flows to the liquid reservoir 6 after condensation into liquid. After flowing out of the liquid reservoir 6, it is filtered by the filter 7. After coming out of the filter 7, the refrigerant passes through the throttling system 8 for throttling and pressure reduction, and the refrigerant becomes gas-liquid two-phase and enters the evaporator 9. The refrigerant exchanges heat with the chilled water therein, absorbs heat and evaporates, and the required chilled water is produced. After absorbing heat, the refrigerant becomes gaseous and enters the open compressor 2 for compression, and the cycle is carried out.

[0064] In this embodiment, a control method for an air-cooled chiller is provided, which is applied to the control unit of the air-cooled chiller in the above embodiment. Figure 3 is a flow chart of the control method of the air-cooled chiller of this embodiment. Figure 3 As shown, the process includes the following steps:

[0065] Step S301, when the air-cooled chiller enters the high-pressure refrigeration operation state, the control unit obtains the exhaust pressure of the open compressor detected by the exhaust pressure sensor.

[0066] In this embodiment, the control unit acquires the exhaust pressure at the exhaust end of the open compressor detected by the exhaust pressure sensor in real time, uses the exhaust pressure as a control parameter, and performs high pressure control based on the exhaust pressure.

[0067] In step S302, the control unit detects whether the exhaust pressure is in a preset exhaust pressure range, and after first detecting that the exhaust pressure is in the preset exhaust pressure range, controls a first device of one of the multiple air-cooled condensing branches to operate in a first working mode, wherein the first device includes a pressure exhaust solenoid valve and one of the two-speed fans of one of the multiple air-cooled condensing branches, and the first working mode includes the corresponding pressure exhaust solenoid valve opening and the corresponding two-speed fan operating at a preset low speed.

[0068] In this embodiment, the set value of the preset exhaust pressure range is 1.2-1.4 MPa. When it is detected that the exhaust pressure is in the preset exhaust pressure range, the first device is started so that the exhaust pressure does not continue to increase.

[0069] Step S303: After the first device operates in the first working mode, the control unit detects the exhaust pressure multiple times at a set time interval.

[0070] In this embodiment, after starting the first device, the effect of reducing the exhaust pressure after the first device starts working cannot offset the progress of the exhaust pressure increase generated by the open compressor during its own working process. Therefore, even after the first device is running, the detected exhaust pressure will still rise to the preset exhaust pressure range. Therefore, in order to ensure that the exhaust pressure is in the preset exhaust pressure range, the exhaust pressure is detected multiple times at set time intervals, and then the corresponding device is started according to the inspection results, so that the exhaust pressure is maintained within the preset exhaust pressure range, thereby maintaining the high pressure stability and the high and low pressure difference stability.

[0071] In step S304, the control unit determines the exhaust pressure operating gear corresponding to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operating gear to operate according to the preset exhaust pressure mode, wherein each preset exhaust pressure mode sets the opening and closing state of the corresponding exhaust pressure solenoid valve and sets the corresponding wind speed gear of the two-speed fan.

[0072] In this embodiment, when the judgment result is that the exhaust pressure is within the preset exhaust pressure range, it indicates that the currently running first device is not sufficient to maintain the exhaust pressure within the preset exhaust pressure range during continued operation, and it is necessary to control the operation of the unstarted exhaust pressure solenoid valve or the two-speed fan in the air-cooled condensation branch, or change the wind speed gear of the running two-speed fan, so as to strengthen the reduction of the exhaust pressure; when the judgment result is that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, it indicates that during the operation of the first device, the effect of the first device on reducing the exhaust pressure is stronger than the effect of the open compressor on enhancing the exhaust pressure. At this time, it is necessary to stop the operation of the first device and increase the exhaust pressure to the preset exhaust pressure range.

[0073] Through the above steps S301 to S304, when the air-cooled chiller enters the operating state of high-pressure refrigeration, the exhaust pressure of the open compressor detected by the exhaust pressure sensor is obtained; the exhaust pressure is detected to be in a preset exhaust pressure range, and after the exhaust pressure is detected to be in the preset exhaust pressure range for the first time, the first device of one of the multiple air-cooled condensing branches is controlled to operate in the first working mode; after the first device operates in the first working mode, the exhaust pressure is detected multiple times at a set time interval; according to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, the exhaust pressure operating gear corresponding to the judgment result is determined, and the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operating gear is controlled to operate in the preset exhaust pressure mode, which solves the problems of unstable high-pressure pressure control and complex logic of air-cooled chillers in related technologies, and realizes the provision of high-pressure pressure stability and maintenance of stable operation of the air-cooled chiller.

[0074] In some embodiments, the control unit determines the exhaust pressure operation gear corresponding to the judgment result according to each judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operation gear to operate in the preset exhaust pressure mode, including the following steps:

[0075] Step 1. After the first device operates in the first working mode, the control unit determines that the exhaust pressure operating gear includes the first gear when it first determines that the exhaust pressure is in the preset exhaust pressure range, wherein the first gear is associated with the first device in one of the multiple air-cooled condensation branches that is not operating in the first working mode.

[0076] In this embodiment, the first device associated with the first gear is another first device belonging to the same air-cooled condensing branch as the first device that was started the last time it was determined that the exhaust pressure was in the preset exhaust pressure range. For example: when it is determined that the exhaust pressure is in the preset exhaust pressure range, the first device that is started is a two-speed fan, and the two-speed fan is set to run at a low speed. Then, after the two-speed fan runs at a low speed, when it is detected for the first time that the exhaust pressure is in the preset exhaust pressure range, the exhaust pressure solenoid valve located in the same air-cooled condensing branch is opened.

[0077] Step 2, the control unit controls the first device in one of the multiple air-cooled condensation branches that is not operating in the first working mode to operate in a preset exhaust pressure mode, and maintains the exhaust pressure in a preset exhaust pressure range.

[0078] In this embodiment, the preset pressure relief mode is the operating mode of the first device in one of the corresponding multi-way air-cooled condensing branches that is not operating in the first working mode. For example, when the first device in one of the multi-way air-cooled condensing branches that is not operating in the first working mode is a pressure relief solenoid valve, then the preset pressure relief mode is to open the pressure relief solenoid valve. If the first device in one of the multi-way air-cooled condensing branches that is not operating in the first working mode is a two-speed fan, the preset pressure relief mode is to start the two-speed fan according to the corresponding wind speed gear, wherein the wind speed gear includes a low speed gear and a high speed gear, but the two-speed fan is set to run at a low speed gear first.

[0079] Through the above steps, after the first device operates in the first working mode, when it is first determined that the exhaust pressure is in the preset exhaust pressure range, it is determined that the exhaust pressure operating gear includes the first gear; the first device in one of the multiple air-cooled condensation branches that is not operating in the first working mode is controlled to operate in the preset exhaust pressure mode, and the exhaust pressure is maintained in the preset exhaust pressure range, so as to achieve the stability of the high-pressure pressure controlled according to the exhaust pressure.

[0080] In some of the embodiments, after the first device operates in the first operating mode, when the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, the control unit executes the following steps: shutting down the first device operating in the first operating mode until the exhaust pressure increases to the preset exhaust pressure range.

[0081] In this embodiment, when the first device is operated in the first working mode, if it is determined that the exhaust pressure is lower than the preset exhaust pressure range, it means that after the first device is operated in the first working mode, the effect of the first device on reducing the exhaust pressure is stronger than the effect of the open compressor on enhancing the exhaust pressure. At this time, it is necessary to stop the operation of the first device to increase the exhaust pressure to the preset exhaust pressure range.

[0082] In some embodiments, after the control unit controls the first device in one of the multiple air-cooled condensing branches that is not operated in the first working mode to operate in the preset exhaust pressure mode, the control unit determines the exhaust pressure operation gear corresponding to the judgment result according to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operation gear to operate in the preset exhaust pressure mode, including the following steps:

[0083] Step 1: When the control unit determines that the exhaust pressure is in the preset exhaust pressure range for multiple consecutive times, it controls the corresponding pressure exhaust solenoid valve or two-speed fan to work in the preset pressure exhaust mode in sequence according to the preset pressure exhaust equipment operation order, until it determines that the exhaust pressure is lower than the preset exhaust pressure range, and then shuts down the pressure exhaust solenoid valve or two-speed fan currently working in the preset pressure exhaust mode.

[0084] In this embodiment, when it is determined that the exhaust pressure is in the preset exhaust pressure range for multiple consecutive times, it means that each time the exhaust pressure is detected to be in the preset exhaust pressure range, the exhaust pressure reduced by the exhaust solenoid valve or the two-speed fan that operates continues to operate, and is lower than the exhaust pressure generated during the operation of the open compressor, so that within a time interval, the exhaust pressure rises, and it is necessary to start the subsequent exhaust solenoid valve or the two-speed fan set according to the operating order of the exhaust pressure equipment to maintain the exhaust pressure in the preset exhaust pressure range.

[0085] Step 2: When the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, it shuts down the exhaust pressure solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode, and restarts the exhaust pressure solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode the next time it determines that the exhaust pressure is in the preset exhaust pressure range.

[0086] In this embodiment, during multiple consecutive judgments, if it is judged that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range at a certain time, it indicates that in the previous detection, it was detected that the exhaust pressure was in the preset exhaust pressure range, and the exhaust pressure solenoid valve or the two-speed fan that was running continued to operate, and the exhaust pressure reduced was higher than the exhaust pressure generated during the operation of the open compressor, so that the exhaust pressure dropped within a time interval. At this time, it is necessary to suspend the exhaust pressure solenoid valve or the two-speed fan that is currently started, so as to maintain the exhaust pressure within the preset exhaust pressure range. At the same time, when the next time interval arrives, it is detected whether the exhaust pressure is in the preset exhaust pressure range. If the exhaust pressure is judged to be in the preset exhaust pressure range next time, it indicates that after suspending the currently running exhaust pressure solenoid valve or the two-speed fan, the operation of the open compressor is to increase the exhaust pressure. In order to maintain the exhaust pressure within the preset exhaust pressure range, it is necessary to restart the exhaust pressure solenoid valve or the two-speed fan that is currently working in the preset exhaust pressure mode, so that the exhaust pressure is maintained within the preset exhaust pressure range within the next time interval.

[0087] Through the above steps, by successively controlling the corresponding pressure relief solenoid valve or the operation of the two-speed fan, the high pressure and high and low pressure difference of the air-cooled chiller can be maintained stable, thereby ensuring the stable operation of the air-cooled chiller.

[0088] The present embodiment is described and illustrated below through preferred embodiments.

[0089] In the preferred embodiment of the present application, six adjustment gears are formed by setting two air-cooled condensing branches and setting a pressure relief solenoid valve for each air-cooled condensing branch. The preset pressure relief equipment operation order from the first gear to the sixth gear is as follows: the first two-speed fan (corresponding to Figure 1 The two-speed fan on the left side of the middle) runs at low speed, and the first row pressure solenoid valve (corresponding to Figure 1 The pressure relief solenoid valve on the left side of the middle) opens, and the second pressure relief solenoid valve (corresponding to Figure 2 The pressure relief solenoid valve on the right side of the middle is opened, the first two-speed fan runs at high speed, and the second two-speed fan (corresponding to Figure 1 The two-speed fan on the right in the middle runs at low speed and the second two-speed fan runs at high speed. Figure 4 is a flow chart of a control method for an air-cooled chiller according to a preferred embodiment of the present application, and the following reference is made to Figure 1 and Figure 4 According to the preferred embodiment of the present application, the control method of the air-cooled or water-cooled unit comprises the following steps:

[0090] Step S401, the open compressor is running.

[0091] Step S402, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S403.

[0092] Step S403: the first dual-speed fan operates at a low speed, and then step S404 is executed.

[0093] Step S404, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S405, otherwise executing step S415.

[0094] In step S405, the first pressure relief solenoid valve is opened, and then step S406 is executed.

[0095] Step S406, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S407, otherwise executing step S416.

[0096] Step S407, the second pressure relief solenoid valve is opened, and then step S408 is executed.

[0097] Step S408, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S409, otherwise executing step S417.

[0098] Step S409: the first dual-speed fan operates at a high speed, and then step S410 is executed.

[0099] Step S410, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S411, otherwise executing step S418.

[0100] Step S411, the second dual-speed fan operates at a low speed, and then step S412 is executed.

[0101] Step S412, determining whether the exhaust pressure is within a preset exhaust pressure range, if yes, executing step S411, otherwise executing step S419.

[0102] Step S413, the second dual-speed fan operates at a high speed, and then step S414 is executed.

[0103] Step S414, determining whether the exhaust pressure is within a preset exhaust pressure range, if not, executing step S420, and then executing step S402.

[0104] Step S415, stop the first dual-speed fan to operate at a low speed.

[0105] Step S416, closing the first exhaust pressure solenoid valve.

[0106] Step S417, closing the second pressure relief solenoid valve.

[0107] Step S418: the first dual-speed fan is switched to a low speed gear.

[0108] Step S419, stop the second dual-speed fan to operate at a low speed.

[0109] Step S420: the second dual-speed fan is switched to a low speed gear.

[0110] The method embodiment provided in this embodiment can be executed in a terminal, a computer or a similar computing device. For example, running on a terminal, Figure 5 : is a hardware structure block diagram of a terminal of the control method of the air-cooled chiller of this embodiment. Figure 5 As shown, the terminal may include one or more ( Figure 5 Only one is shown in the figure) processor 502 and memory 504 for storing data, wherein processor 502 may include but is not limited to a processing device such as a microprocessor MCU or a programmable logic device FPGA. The above terminal may also include a transmission device 506 and an input and output device 508 for communication functions. It can be understood by those skilled in the art that Figure 5 The structure shown is only for illustration and does not limit the structure of the above terminal. Figure 5 More or fewer components as shown, or with Figure 5 Different configurations shown.

[0111] The memory 504 can be used to store computer programs, for example, software programs and modules of application software, such as the computer programs corresponding to the method in the present embodiment. The processor 502 executes various functional applications and data processing by running the computer programs stored in the memory 504, that is, the above-mentioned method is realized. The memory 504 may include a high-speed random access memory, and may also include a non-volatile memory, such as one or more magnetic storage devices, flash memory, or other non-volatile solid-state memory. In some examples, the memory 504 may further include a memory remotely arranged relative to the processor 502, and these remote memories may be connected to the terminal via a network. Examples of the above-mentioned network include, but are not limited to, the Internet, an intranet, a local area network, a mobile communication network, and combinations thereof.

[0112] The transmission device 506 is used to receive or send data via a network. The above network includes a wireless network provided by the communication provider of the terminal. In one example, the transmission device 506 includes a network adapter (Network Interface Controller, referred to as NIC), which can be connected to other network devices through a base station so as to communicate with the Internet. In one example, the transmission device 506 can be a radio frequency (RF) module, which is used to communicate with the Internet wirelessly.

[0113] It should be understood that the specific embodiments described herein are only used to explain the application, rather than to limit it. Based on the embodiments provided in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the protection scope of this application.

[0114] Obviously, the drawings are only some examples or embodiments of the present application. For ordinary technicians in the field, the present application can also be applied to other similar situations based on these drawings without creative work. In addition, it is understandable that although the work done in this development process may be complicated and lengthy, for ordinary technicians in the field, certain changes in design, manufacturing or production based on the technical content disclosed in this application are only conventional technical means and should not be regarded as insufficient content disclosed in this application.

[0115] The term "embodiment" in this application refers to a specific feature, structure or characteristic described in conjunction with the embodiment that can be included in at least one embodiment of the present application. The appearance of this phrase in various locations in the specification does not necessarily mean the same embodiment, nor does it mean that it is mutually exclusive with other embodiments and is independent or optional. It is clearly or implicitly understood by those of ordinary skill in the art that the embodiments described in this application can be combined with other embodiments without conflict.

[0116] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of patent protection. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the scope of protection of the present application. Therefore, the scope of protection of the present application shall be subject to the attached claims.

Claims

1. An air-cooled chiller, comprising a nuclear-grade motor (1) and an open compressor (2) connected to the nuclear-grade motor (1), characterized in that: The open compressor (2) is connected to the oil separator (3), the condensing system, the liquid storage device (6), the throttling system (8) and the evaporator (9) in sequence through a refrigerant pipeline to form a refrigerant circulation loop, wherein an exhaust pressure sensor (15) is provided on the refrigerant pipeline connecting the open compressor (2) and the oil separator (3); the condensing system comprises a plurality of parallel air-cooled condensing branches, each of which comprises a condenser (5), a two-speed fan (4) and an exhaust pressure solenoid valve (18); The condenser (5) comprises a condensation inlet and a condensation outlet, the condensation inlet is connected to the gas outlet of the oil separator (3) through a first pipeline, and at least one of the first pipelines between the condensation inlet and the gas outlet is provided with the pressure discharge solenoid valve (18), the condensation outlet is connected to the liquid reservoir (6) through a second pipeline, the two-speed fan (4) is arranged on the condenser (5), and the exhaust pressure sensor (15), the pressure discharge solenoid valve (18) and the two-speed fan (4) are all electrically connected to a control unit; When the air-cooled chiller enters a high-pressure refrigeration operation state, the control unit acquires the exhaust pressure of the open compressor detected by the exhaust pressure sensor; The control unit detects whether the exhaust pressure is in a preset exhaust pressure interval, and after first detecting that the exhaust pressure is in the preset exhaust pressure interval, controls a first device in one of the multiple air-cooled condensing branches to operate in a first working mode, wherein the first device includes a pressure discharge solenoid valve and one of a two-speed fan in one of the multiple air-cooled condensing branches, and the first working mode includes the corresponding pressure discharge solenoid valve being opened and the corresponding two-speed fan operating at a preset low speed; After the first device operates in the first working mode, the control unit detects the exhaust pressure multiple times at a set time interval; The control unit determines the pressure exhaust operation gear corresponding to the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the pressure exhaust solenoid valve or the two-speed fan associated with the pressure exhaust operation gear to operate in a preset pressure exhaust mode, wherein each preset pressure exhaust mode sets the corresponding opening and closing state of the pressure exhaust solenoid valve and sets the corresponding wind speed gear of the two-speed fan.

2. The air-cooled chiller according to claim 1, characterized in that: At least one of the second pipelines between the condensation outlet and the liquid storage tank (6) is provided with a first one-way valve (19), wherein the first one-way valve (19) is used to prevent the refrigerant from flowing back to the condenser (5).

3. The air-cooled chiller according to claim 1, characterized in that: The condenser (5) comprises a finned heat exchanger.

4. The air-cooled chiller according to claim 1, characterized in that: The evaporator (9) comprises a nuclear-grade flooded evaporator.

5. The air-cooled chiller according to claim 1, characterized in that: A filter (7) is provided on the refrigerant pipeline between the liquid reservoir (6) and the throttling system (8), wherein the filter (7) is used to dry the refrigerant output along the liquid reservoir (6).

6. The air-cooled chiller according to claim 1, characterized in that: An exhaust temperature sensor (14) is also provided on the refrigerant pipeline between the open compressor (2) and the oil separator (3), and an intake temperature sensor (16) and an intake pressure sensor (17) are provided on the refrigerant pipeline between the evaporator (9) and the open compressor (2), wherein the exhaust temperature sensor (14), the intake temperature sensor (16) and the intake pressure sensor (17) are all electrically connected to the control unit.

7. The air-cooled chiller according to claim 1, characterized in that: The throttling system (8) comprises an electronic expansion valve.

8. The air-cooled chiller according to claim 1, characterized in that: An oil circuit for supplying oil to the open compressor (2) is also provided between the oil separator (3) and the open compressor (2), wherein the oil circuit comprises an oil filter (10), the input end of the oil filter (10) is connected to the oil outlet of the oil separator (3) via an oil pipe, the output end of the oil filter (10) is respectively connected to the input end of a first oil return branch and the input end of a second oil return branch, the output end of the first oil return branch is connected to the capacity adjustment slide valve of the open compressor (2), and the output end of the second oil return branch is respectively connected to the suction and exhaust end bearings of the open compressor (2) and the capacity adjustment slide valve, wherein the first oil return branch is used to supply oil to the open compressor (2) when the open compressor (2) is started or the high and low pressure difference is less than a preset threshold value, and the second oil return branch is used to supply oil to the open compressor (2) after the open compressor (2) is started and / or when the high and low pressure difference is not less than a preset threshold value.

9. The air-cooled chiller according to claim 8, characterized in that: The first oil return branch comprises an oil pump (11) and a check valve (12) connected in series via the oil pipe, the input end of the oil pump (11) is connected to the output end of the oil separator (3) via the oil pipe, and the other end of the check valve (12) is connected to the capacity adjustment slide valve via the oil pipe; the second oil return branch comprises two second one-way valves arranged in parallel, one end of the two second one-way valves is connected to the output end of the oil filter (10) via the oil pipe, and the other end of the two second one-way valves is respectively connected to the suction and exhaust end bearings of the open compressor (2) and the capacity adjustment slide valve via the oil pipe.

10. The air-cooled chiller according to claim 9, characterized in that: An oil pressure sensor (13) is provided on the oil pipe between the capacity adjustment slide valve and the check valve (12).

11. A control method for an air-cooled water chiller, the air-cooled water chiller comprising the air-cooled water chiller according to any one of claims 1 to 10, characterized in that: The control method comprises: The control unit determines that the exhaust pressure operation gear includes a first gear when it is first determined that the exhaust pressure is in the preset exhaust pressure range after the first device is operated in the first working mode, wherein the first gear is associated with the first device in one of the multiple air-cooled condensing branches that is not operated in the first working mode; The control unit controls the first device in one of the multiple air-cooled condensation branches that is not operating in the first working mode to operate in the preset exhaust pressure mode, and maintains the exhaust pressure in the preset exhaust pressure range.

12. The control method of the air-cooled chiller according to claim 11, characterized in that: After the first device operates in the first operating mode, when the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, the control unit shuts down the first device operating in the first operating mode until the exhaust pressure increases to the preset exhaust pressure range.

13. The control method of the chiller according to claim 11, characterized in that: After the control unit controls the first device in one of the multiple air-cooled condensing branches that is not operating in the first working mode to operate in the preset exhaust pressure mode, the control unit determines the exhaust pressure operation gear corresponding to the judgment result based on the judgment result of whether the detected exhaust pressure is in the preset exhaust pressure range each time, and controls the exhaust pressure solenoid valve or the two-speed fan associated with the exhaust pressure operation gear to operate in the preset exhaust pressure mode, including: When the control unit determines that the exhaust pressure is within the preset exhaust pressure range for multiple times in a row, the control unit controls the corresponding exhaust pressure solenoid valve or the two-speed fan to work in the preset exhaust pressure mode in sequence according to the preset exhaust pressure equipment operation order, until the control unit determines that the exhaust pressure is lower than the preset exhaust pressure range, and then shuts down the exhaust pressure solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode; When the control unit determines that the exhaust pressure is lower than the lower limit of the preset exhaust pressure range, it shuts down the pressure exhaust solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode, and restarts the pressure exhaust solenoid valve or the two-speed fan currently working in the preset exhaust pressure mode when it determines that the exhaust pressure is in the preset exhaust pressure range next time.

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