Large-capacity evaporative cooling type variable frequency air suspension centrifugal water chiller

Abstract

The utility model discloses a kind of large-capacity evaporative cooling type frequency conversion air suspension centrifugal water chiller, it is related to refrigeration and refrigeration equipment field, including compressor, condenser, evaporator, economic device efficiency unit, compressor motor cooling unit, compressor frequency converter cooling unit, hot gas bypass unit, refrigeration hydraulic module unit and pipeline and control loop.The utility model fuses and applies evaporative condensation technology, compressor air suspension technology, frequency conversion technology, simultaneously integrates refrigeration water and cooling water conveying device, and further improves the reliability and operating efficiency of large-capacity air suspension centrifugal compressor application, increases evaporative condenser service life, improves the current design deficiency of integrated unit, and proposes a kind of highly integrated efficient and reliable water chiller.

Description

Technical Field

[0001] This utility model relates to the field of refrigeration and freezing equipment, specifically to a large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit. Background Technology

[0002] Evaporative cooling is a highly efficient, energy-saving, and water-saving technology. It involves spraying cooling water onto the surface of a heat exchanger to form a continuous water film. The water absorbs heat through evaporation, exchanging heat with the refrigerant fluid inside the heat exchanger. The refrigerant is rapidly cooled, and the vaporized water transfers heat to the airflow, which is then exhausted by a fan. This method is more than 45% more efficient than air-cooled cooling. In recent years, with the upgrading of energy efficiency in chiller units, the use of evaporative cooling condensers has become a preferred option. However, evaporative condensers also suffer from problems such as easy corrosion and scaling of the heat exchange tubes, resulting in a relatively high water drift rate, which requires significant attention.

[0003] Air suspension + variable frequency technology for compressors is a highly efficient and energy-saving technology. Its core component is the compressor's air suspension bearing, which uses air pressure to suspend the rotor in the air, eliminating mechanical contact between the rotor and stator. This technology offers numerous advantages, including oil-free operation, frictionless operation, low noise, and low power consumption, significantly improving the compressor's energy efficiency under partial load. Air suspension variable frequency centrifugal compressors are relatively new, especially large-capacity compressors with a cooling capacity of 300RT (1055kW) or higher, which are still in the research and development stage. Improvements in reliable and practical application technologies are needed. For example, large-capacity compressor motors and inverter modules generate significant heat, requiring effective cooling and accurate temperature control. The compressor motor temperature needs to be kept below 85℃, and the inverter module temperature below 90℃. Conventional refrigerant liquid cooling, air cooling, and water cooling methods require improvement.

[0004] In recent years, the demand for integrated central air conditioning units that combine chilled water and cooling water delivery functions has been increasing. However, current integrated products have the disadvantages of large unit size and heavy weight. Some units have unreasonable chilled water system design, simplified functional components, and when the user's water system is tested, it is difficult to prevent dirt from entering the evaporator. These problems result in low reliability and inconvenient maintenance. Utility Model Content

[0005] The purpose of this utility model is to overcome the shortcomings of existing technologies and provide a large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit. The product development direction is to adopt new energy-saving technologies. To this end, evaporative condensation technology, compressor air suspension technology, and variable frequency technology can be integrated. At the same time, chilled water and cooling water conveying devices are integrated, and the reliability and operating efficiency of the large-capacity air suspension centrifugal compressor application are further improved, the service life of the evaporative condenser is increased, and the shortcomings of the current integrated unit design are improved, thus proposing a highly integrated, efficient and reliable chiller unit.

[0006] The purpose of this utility model is achieved through the following technical solution: This large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit includes a compressor, a condenser, an evaporator, an economizer efficiency enhancement unit, a compressor motor cooling unit, a compressor inverter cooling unit, a hot gas bypass unit, a chilled water hydraulic module unit, and pipelines and control circuits. The compressor is an air-suspension variable frequency centrifugal compressor. The compressor's exhaust port is connected to the inlet of the evaporative condenser, the evaporative condenser outlet is connected to the tube-side inlet of the evaporator, and the tube-side outlet of the evaporator is connected to the compressor's suction port. The compressor motor liquid supply interface is connected to the outlet of the evaporative condenser through the compressor motor cooling unit, and the compressor motor cooling outlet interface is connected to the top of the evaporator; the economizer efficiency enhancement unit includes an economizer heat exchanger, and the outlet liquid pipe of the evaporative condenser has two connections to the economizer heat exchanger, one of which is equipped with an economizer throttling device and leads to the auxiliary channel inlet of the economizer heat exchanger, and the auxiliary channel outlet of the economizer efficiency enhancement unit is connected to the economizer interface of the compressor; the other leads to the main channel inlet of the economizer heat exchanger, and the main channel outlet of the economizer heat exchanger is connected to the evaporator; The compressor inverter cooling unit is connected between the outlet liquid pipes of the evaporator and the evaporative condenser. The hot gas bypass unit is connected between the exhaust port and the evaporator. The chilled water module unit is connected to the water-side inlet and outlet of the evaporator and is connected to the inlet and outlet of the user end.

[0007] As a further technical solution, the economizer efficiency enhancement unit also includes an economizer filter and an electric valve. The economizer plate heat exchanger is a subcooled type plate heat exchanger. The economizer filter is connected to the liquid outlet pipeline of the evaporative condenser. The inlet of the economizer throttling device is connected after the economizer filter. The outlet of the economizer throttling device is connected to the inlet of the auxiliary channel of the economizer plate heat exchanger. The outlet of the auxiliary channel of the economizer plate heat exchanger is connected to the economizer interface through an electric valve. The main channel outlet of the economizer plate heat exchanger is connected to the evaporator in sequence through a maintenance valve, a dryer filter, and a throttling device.

[0008] As a further technical solution, the compressor motor cooling unit includes a motor throttling device, a motor filter, and a motor maintenance valve connected in sequence through pipelines. The inlet of the motor maintenance valve is connected to the liquid outlet pipeline of the evaporative condenser. The motor throttling device is connected to the motor liquid supply interface of the compressor and provides low-temperature two-phase refrigerant cooling to the compressor motor, so that the motor temperature is less than 70°C during the full operating condition of the compressor. The heat-exchanged fluid returns to the evaporator through the motor cooling outlet interface.

[0009] As a further technical solution, the compressor inverter cooling unit includes an inverter maintenance valve, an inverter filter, an inverter throttling device, and an inverter cooler connected in sequence via pipelines. The inlet of the inverter maintenance valve is connected to the liquid pipeline at the outlet of the evaporative condenser. The inverter throttling device provides low-temperature two-phase refrigerant cooling to the compressor inverter module, ensuring that the temperature of the compressor inverter module is less than 80°C under all operating conditions. The fluid after heat exchange flows back to the gas phase space above the evaporator shell through the inverter cooler.

[0010] As a further technical solution, an exhaust check valve is installed on the connecting pipe between the compressor's exhaust port and the evaporative condenser. The hot gas bypass unit has two branches. The first branch is connected between the exhaust port and the exhaust check valve. Through the first hot gas bypass valve installed on the first branch, the high-temperature and high-pressure hot gas from the exhaust port is directed to the gas phase space at the top of the evaporator. The second branch is connected after the exhaust check valve. Through the second hot gas bypass valve installed on the second branch, the high-temperature and high-pressure hot gas from the compressor exhaust flowing through the exhaust check valve pipe is directed to the bottom liquid phase space of the evaporator.

[0011] As a further technical solution, the chilled water module unit includes a chilled water pump. One end of the chilled water pump is connected in sequence to a filter, a first water circuit valve, an expansion tank, a safety valve, and a pressure gauge, and is connected to the user-side return water. The other end of the chilled water pump is connected in sequence to a flexible joint, a check valve, an electronic descaling device, and a second water circuit valve, and is connected to the water-side inlet of the evaporator. A third water circuit valve is installed at the water-side outlet of the evaporator and connected to the user-side outlet water.

[0012] As a further technical solution, a flow switch is connected to the second water valve and the third water valve via a bypass. The second water valve and the electronic descaling device are connected to the user-side outlet via a pipeline, and a fourth water valve and an automatic air vent valve are provided on the pipeline. A bypass pipeline is provided between the filter and the first water valve, and a fifth water valve and an automatic water supply valve are connected in parallel on the bypass pipeline, and a water supply port is provided. A drain valve is provided between the chilled water pump and the filter.

[0013] As a further technical solution, the evaporative condenser includes an evaporative air cooler arranged in the center, evaporative cooling coils symmetrically arranged on both sides of the evaporative condenser, and a spray water pump connected to a spray head installed above the evaporative cooling coils.

[0014] As a further technical solution, the compressor's intake port is equipped with an IGV inlet guide vane intake regulating valve.

[0015] The beneficial effects of this utility model are as follows: 1. Compared with existing ordinary centrifugal chiller units, the unit's operating efficiency is significantly improved, by more than 30%; 2. Compared with existing similar products, the heat exchange tubes of the evaporative condenser are made of stainless steel SUS316L and continuously bent, which significantly reduces the risk of corrosion failure; the symmetrical structural layout of the condenser reduces the drift rate to as low as 0.002% of the cooling water circulation volume. 3. It adopts a large-capacity air-suspended centrifugal compressor, with technical measures to prevent surge and improve the compressor's operating range, making it safer to operate and significantly improving its reliability. 4. The integrated unit design incorporates a chilled water pump hydraulic module unit, saving on engineering costs and reducing investment for users; 5. Bypass branches are designed in the chilled water hydraulic transmission unit to effectively prevent the heat exchanger from getting dirty and clogged during testing, thereby enhancing reliability and facilitating maintenance. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the pipeline connection structure in Embodiment 1 of this utility model.

[0017] Figure 2 This is a schematic diagram of the pipeline connection structure in Embodiment 2 of this utility model.

[0018] Figure 3 This is a schematic diagram of the main structure of the present invention after assembly.

[0019] Figure 4 This is a top view of the assembled structure of this utility model.

[0020] Figure 5 This is a side view of the assembled structure of this utility model.

[0021] Explanation of reference numerals in the attached diagram: Compressor 1, Suction port 1-a, Discharge port 1-b, Motor liquid supply interface 1j1, Motor cooling outlet interface 1j2, Economizer interface 1j3, Evaporative condenser 2, Evaporative air cooler 2-a, Evaporative cooling coil 2-b, Spray water pump 2-c, Evaporator 3, Throttling device 4, Discharge check valve 5, Inspection valve 6, Dryer filter 7, Evaporator level gauge 8, Motor throttling device DJ-1, Motor filter DJ-2, Motor inspection valve DJ-3, Inverter cooler BP-0, Inverter throttling device BP-1, Inverter filter BP-2, Inverter inspection valve BP-3, Economizer Plate heat exchanger E-0, economizer throttling device E-1, economizer filter E-2, electric valve E-3, first hot gas bypass valve PT-1, second hot gas bypass valve PT-2, chilled water pump M-1, filter M-2, check valve M-3, electronic descaling device M-4, automatic air vent valve M-5, water flow switch M-6, expansion tank M-7, safety valve M-8, automatic water supply valve M-9, first water circuit valve M-10, second water circuit valve M-11, third water circuit valve M-12, fourth water circuit valve M-13, drain valve M-14, fifth water circuit valve M-15, flexible joint M-16, pressure gauge M-17. Detailed Implementation

[0022] The present invention will now be described in detail with reference to the accompanying drawings: Example 1: As shown in the attached document Figure 1 , 3As shown in Figure 5, this large-capacity evaporative cooling variable frequency air-suspension centrifugal chiller unit includes a compressor 1, an air intake 1-a, an exhaust 1-b, a motor liquid supply interface 1j1, a motor cooling air outlet 1j2, an economizer interface 1j3, an evaporative condenser 2, an evaporative air cooler 2-a, an evaporative cooling coil 2-b, a spray water pump 2-c, an evaporator 3, a throttling device 4, an exhaust check valve 5, a maintenance valve 6, a dryer filter 7, an evaporator level gauge 8, a motor throttling device DJ-1, a motor filter DJ-2, a motor maintenance valve DJ-3, a frequency converter cooler BP-0, a frequency converter throttling device BP-1, a frequency converter filter BP-2, a frequency converter maintenance valve BP-3, an economizer plate heat exchanger E-0, an economizer throttling device E-1, and an economizer filter E. -2. Electric valve E-3, First hot gas bypass valve PT-1, Second hot gas bypass valve PT-2, Chilled water pump M-1, Filter M-2, Check valve M-3, Electronic descaling device M-4, Automatic air vent valve M-5, Flow switch M-6, Expansion tank M-7, Safety valve M-8, Automatic water supply valve M-9, First water circuit valve M-10, Second water circuit valve M-11, Third water circuit valve M-12, Fourth water circuit valve M-13, Drain valve M-14, Fifth water circuit valve M-15, Flexible joint M-16, Pressure gauge M-17, Economizer efficiency enhancement unit (E), Compressor motor cooling unit (DJ), Compressor inverter cooling unit (BP), Hot gas bypass unit (PT), Chilled water hydraulic module unit (M), and piping and control circuits.

[0023] Reference Appendix Figure 1 The compressor 1 is an air-suspension variable frequency centrifugal compressor. The exhaust port 1-b of the compressor 1 is connected to the inlet of the evaporative condenser 2, the outlet of the evaporative condenser 2 is connected to the tube-side inlet of the evaporator 3, and the tube-side outlet of the evaporator 3 is connected to the suction port 1-a of the compressor 1. Furthermore, the compressor 1 is also equipped with a motor liquid supply interface 1j1, a motor cooling outlet interface 1j2, and an economizer interface 1j3. The motor liquid supply interface 1j1 of the compressor 1 is connected to the outlet of the evaporative condenser 2 through the compressor motor cooling unit (motor throttling device DJ-1), and the motor cooling outlet interface 1j2 of the compressor 1 is connected to the top of the evaporator 3. In addition, the economizer efficiency enhancement unit includes an economizer plate heat exchanger E-0 and an economizer throttling device E-1. Two branches are provided at the outlet liquid pipe of the evaporative condenser 2, which are connected to the economizer plate heat exchanger E-0. One branch is equipped with the economizer throttling device E-1 and leads to the auxiliary channel inlet of the economizer plate heat exchanger E-0. The auxiliary channel outlet of the economizer efficiency enhancement unit is connected to the economizer interface 1j3 of the compressor 1 through a check valve M-3. The other branch leads to the main channel inlet of the economizer plate heat exchanger E-0. The main channel outlet of the economizer plate heat exchanger E-0 is connected to the evaporator 3 in sequence through a maintenance valve 6, a dryer filter 7, and a throttling device 4.

[0024] Furthermore, the inverter throttling device BP-1 and the inverter cooler BP-0 together form the compressor inverter cooling unit, which is connected between the outlet liquid pipes of the evaporator 3 and the evaporative condenser 2.

[0025] An exhaust check valve 5 is installed on the connecting pipe between the exhaust port 1-b of compressor 1 and the evaporative condenser 2. The hot gas bypass unit has two branches. The first branch connects the exhaust port 1-b and the exhaust check valve 5. Through the first hot gas bypass valve PT-1 installed on the first branch, the high-temperature and high-pressure hot gas from the exhaust port 1-b is directed to the gas phase space at the top of the evaporator 3. The second branch connects after the exhaust check valve 5. Through the second hot gas bypass valve PT-2 installed on the second branch, the high-temperature and high-pressure hot gas from the compressor exhaust flowing through the exhaust check valve 5 is directed to the bottom liquid phase space of the evaporator 3.

[0026] Furthermore, the chilled water hydraulic module unit is connected to the water-side inlet and outlet of the evaporator 3, and is also connected to the inlet and outlet of the user end. The chilled water hydraulic module unit includes a chilled water pump M-1. One end of the chilled water pump M-1 is sequentially connected to a filter M-2, a first water circuit valve M-10, an expansion tank M-7, a safety valve M-8, and a pressure gauge M-17, and is connected to the user-side return water. The other end of the chilled water pump M-1 is sequentially connected to a flexible connector M-16, a check valve M-3, an electronic descaling device M-4, and a second water circuit valve M-11, and is connected to the water-side inlet of the evaporator 3. The water-side outlet of the evaporator 3 is equipped with a third water circuit valve M-12 and is connected to the user-side outlet water.

[0027] In addition, a flow switch M-6 is connected in a bypass connection between the second water circuit valve M-11 and the third water circuit valve M-12. The second water circuit valve M-11 and the electronic descaling device M-4 are connected in a bypass pipeline to the user's outlet, and the pipeline is equipped with a fourth water circuit valve M-13 and an automatic air vent valve M-5. A bypass pipeline is provided between the filter M-2 and the first water circuit valve M-10. A fifth water circuit valve M-15 and an automatic water replenishment valve M-9 are connected in parallel on the bypass pipeline, and a water replenishment port is provided. A drain valve M-14 is provided between the chilled water pump M-1 and the filter M-2.

[0028] like Figure 3 , 4 As shown in Figure 5, the evaporative condenser 2 includes a centrally located evaporative air cooler 2-a, symmetrically arranged evaporative cooling coils 2-b on both sides of the evaporative condenser 2, and a spray water pump 2-c connected to a spray head located above the evaporative cooling coils 2-b. Preferably, the suction port 1-a of the compressor 1 is equipped with an IGV inlet guide vane suction regulating valve. To prevent liquid carryover during centrifugal compressor suction, an evaporator level gauge 8 is installed on the evaporator 3. By controlling the liquid level in the evaporator 3, liquid carryover during compressor suction is effectively prevented.

[0029] Example 2: Figure 2 As shown, the difference from Embodiment 1 is that the economizer efficiency enhancement unit also includes an economizer filter E-2 and an electric valve E-3. The economizer plate heat exchanger E-0 is a subcooled plate heat exchanger. The economizer filter E-2 is connected to the liquid outlet pipe of the evaporative condenser 2. The inlet of the economizer throttling device E-1 is connected to the downstream of the economizer filter E-2. The outlet of the economizer throttling device E-1 is connected to the inlet of the auxiliary channel of the economizer plate heat exchanger E-0. The outlet of the auxiliary channel of the economizer plate heat exchanger E-0 is connected to the economizer interface 1j3 through the electric valve E-3.

[0030] Furthermore, the compressor motor cooling unit includes a motor throttling device DJ-1, a motor filter DJ-2, and a motor maintenance valve DJ-3 connected in sequence via pipelines. The inlet of the motor maintenance valve DJ-3 is connected to the liquid outlet pipeline of the evaporative condenser 2. The motor throttling device DJ-1 is connected to the motor liquid supply interface 1j1 of the compressor 1 and provides low-temperature two-phase refrigerant cooling to the motor of the compressor 1, so that the motor temperature is less than 70°C during the full operating condition of the compressor. The fluid after heat exchange returns to the evaporator 3 through the motor cooling outlet interface 1j2.

[0031] In addition, the compressor inverter cooling unit includes an inverter maintenance valve BP-3, an inverter filter BP-2, an inverter throttling device BP-1, and an inverter cooler BP-0 connected in sequence by pipelines. The inlet of the inverter maintenance valve BP-3 is connected to the liquid pipeline at the outlet of the evaporative condenser 2. The inverter throttling device BP-1 provides low-temperature two-phase refrigerant cooling to the compressor inverter module, so that the temperature of the compressor inverter module is less than 80°C under all operating conditions. The fluid after heat exchange flows back to the gas phase space above the evaporator 3 cylinder through the inverter cooler BP-0.

[0032] Example 3: As Figure 3 , 4Figure 5 shows a 350RT (1230kW) R134a high-efficiency evaporative cooling variable frequency air-suspended centrifugal chiller unit. It consists of a compressor 1, evaporative condenser 2, evaporator 3, throttling device 4, exhaust check valve 5, dryer filter 7, evaporator level gauge 8, economizer efficiency unit E, compressor motor cooling unit DJ, compressor inverter cooling unit BP, hot gas bypass unit PT, and control circuit. The unit also incorporates a chilled water module unit M. This unit adopts a functional segment unit design layout, divided into three functional module units: the main unit, the evaporative cooling unit, and the chilled water module unit M. The main unit and the evaporative cooling unit are the most important structural units, designed in parallel to ensure a high degree of independence in their function and construction and maintenance. The chilled water module unit M is embedded in the main unit, forming an integrated structure. The unit's dimensions are 8900L*2830W*3180H. Compared to current integrated central air conditioning units with this function, its structure is very compact, suitable for transportation, and convenient for operation and maintenance.

[0033] Compressor 1 is a large-capacity variable frequency air-suspended centrifugal compressor with a cooling capacity of 350RT, equipped with an IGV regulating valve and an economizer efficiency enhancement design. The economizer efficiency enhancement unit E consists of a brazed plate heat exchanger E-0, an electronic expansion valve E-1, a filter E-2, and a solenoid valve E-3. The solenoid valve E-3 controls the activation and deactivation of the economizer function. The compressor is equipped with an IGV regulating valve, a hot gas bypass unit PT, a compressor motor cooling unit DJ, a compressor inverter cooling unit BP, and other economizer efficiency enhancement technologies, which can adapt to partial load operation, prevent compressor surge, and widen the compressor's operating range.

[0034] Evaporative condenser 2 and evaporative cooling coil 2-b are designed as modular units, using 6 groups arranged symmetrically. Evaporative cooling coil 2-b is a coil composed of a serpentine tube bundle. The heat exchange tubes are made of SUS316L stainless steel, and each heat exchange tube is continuously bent to ensure strong corrosion resistance. The heat exchange tube diameter is 9.52mm, each serpentine flow channel has a total length of 12 meters, and the refrigerant mass flow velocity inside the tube does not exceed 190kg / m³. 2 The design ensures efficient heat exchange while maintaining a low flow pressure drop. The evaporative air cooler 2-a employs three large-diameter, high-static-pressure, low-noise axial flow fans, with noise levels less than 78 dB(A). Centrally positioned within the condenser unit, it provides uniform airflow and minimizes drift compared to conventional units. The spray pump 2-c is a low-head, high-flow-rate pump specifically designed for cooling towers, with a flow rate of 220 m³ / h. This allows for a large spray volume, rapidly reducing coil surface temperature and preventing scale buildup. The evaporative condenser 2 features a co-current airflow and water flow structure, resulting in high heat exchange efficiency and preventing scale buildup on the heat exchange tube surface due to dry evaporation.

[0035] Evaporator 3 is a flooded shell-and-tube heat exchanger with a cylinder diameter of 630mm. A level gauge 8 is installed on the evaporator cylinder to control the liquid level inside the evaporator cylinder, preventing liquid carryover during compressor suction and avoiding damage to the compressor. The evaporator cylinder receives return refrigerant from compressor motor cooling, compressor inverter module cooling, and compressor hot gas bypass.

[0036] The refrigeration cycle system of the unit consists of four main components: a high-efficiency air-suspended variable frequency centrifugal compressor 1, a high-efficiency evaporative condenser 2, a high-efficiency flooded evaporator 3, and a throttling electronic expansion valve 4, along with an economizer efficiency enhancement function. During refrigeration operation, the exhaust from compressor 1 passes through check valve 5 and then to the evaporative condenser 2 for efficient cooling via evaporation and condensation. The high-temperature, high-pressure refrigerant gas is cooled into a liquid and then filtered through economizer filter E-2 before entering the economizer efficiency enhancement unit E. Economizer E-0 is a brazed plate heat exchanger. The main channel fluid is the high-temperature refrigerant liquid formed by cooling in the evaporative condenser 2, while the auxiliary channel is the low-temperature, low-pressure two-phase refrigerant fluid formed by throttling device E-1. After convective heat exchange between the two fluids, the liquid in the main channel becomes a subcooled liquid and enters the throttling device 4 for pressure and temperature reduction. The low-temperature, low-pressure two-phase refrigerant fluid formed by throttling enters the evaporator 3 for heat exchange. The refrigerant absorbs heat from the chilled water and becomes a superheated gas, which is then drawn into compressor 1 for compression and work before being discharged, completing one refrigeration cycle. After the refrigerant two-phase fluid in the economizer auxiliary channel is converted into superheated gas through heat exchange, it returns to the compressor 1 economizer interface 1j3 via solenoid valve E-3.

[0037] The hot gas bypass unit PT consists of two branches: hot gas bypass valve PT-1 and hot gas bypass valve PT-2. The inlet of branch PT-1 is located on the pipeline between the compressor discharge port and the discharge check valve 5, and the outlet is at evaporator 3. Evaporator 3 is a shell-and-tube heat exchanger, with a gas phase space above the shell. When hot gas bypass valve PT-1 is opened, high-temperature, high-pressure refrigerant is rapidly introduced into the large gas phase space within the evaporator shell, balancing the high and low pressures and suppressing the adverse effects of discharge back pressure on the air-suspended centrifugal compressor. The inlet of branch PT-2 is located on the pipeline between the compressor discharge check valve 5 and the condenser 2, and the outlet is at the bottom of evaporator 3. Evaporator 3 is a flooded heat exchanger, with a liquid phase region at the bottom of the shell. When hot gas bypass valve PT-2 is opened, high-temperature, high-pressure refrigerant is introduced into the liquid phase region at the bottom of the shell, effectively raising the refrigerant temperature, reducing heat exchange between the chilled water and the refrigerant, and preventing a rapid drop in chilled water temperature.

[0038] The compressor motor cooling unit DJ consists of an electronic expansion valve DJ-1, a filter DJ-2, and a maintenance valve DJ-3. The DJ branch inlet originates from the liquid outlet pipe of the condenser. After throttling by the electronic expansion valve DJ-1, the refrigerant flows to the compressor motor liquid supply interface 1j1. After cooling the motor, the refrigerant becomes superheated gas and flows from the compressor motor cooling outlet interface 1j2. The DJ branch outlet is located in the gas phase space above the evaporator 3 cylinder. This cooling and temperature control method ensures that the compressor motor winding temperature remains below 70℃ throughout the entire operating range, effectively preventing motor overheating.

[0039] The compressor inverter cooling unit BP consists of an electronic expansion valve BP-1, a filter BP-2, and a maintenance valve BP-3. The BP branch inlet originates from the liquid pipeline at the condenser outlet. After throttling by the electronic expansion valve BP-1, the refrigerant flows to the compressor inverter cooling unit BP-0. After cooling the inverter module, the refrigerant becomes superheated gas and finally flows into the gas phase space above the evaporator 3 cylinder. This cooling and temperature control method ensures that the inverter module temperature remains below 80℃ throughout the entire operating range, guaranteeing stable and reliable inverter operation.

[0040] The unit integrates a chilled water hydraulic transport module M, which mainly consists of a chilled water pump M-1, a filter M-2, a check valve M-3, an electronic descaling device M-4, an automatic air vent valve M-5, a flow switch M-6, an expansion tank M-7, a safety valve M-8, an automatic water supply valve M-9, a drain valve M-14, a flexible connector M-16, a pressure gauge M-17, and necessary water circuit valves M-10, 11, 12, 13, and 15. It has automatic water supply, pressure stabilization, automatic air venting, automatic pressure relief, water treatment and drainage, and bypass functions. Water circuit valves, consisting of valves M-11, 12, and 13, are designed at the water side inlet and outlet of evaporator 3, forming a bypass branch. This bypass branch can be opened or closed to completely cut off the water flow into the heat exchanger or reduce the circulating water flow into the heat exchanger. This prevents dirty water from entering the heat exchanger during the unit's engineering water system commissioning and cleaning, thus protecting the evaporator. Alternatively, if the evaporator water flow is too high, the evaporator water flow rate can be reduced to decrease the water velocity in the heat exchange tubes, further protecting the evaporator. The chilled water module unit is easy to maintain; only the relevant valves inside the unit need to be operated, and it is unrelated to the operation of valves at the user end outside the unit. Closing valves M-10, M-11, and M-13 and opening drain valve M-14 allows for the removal and cleaning of filter M-2 and maintenance of chilled water pump M-1. Closing evaporator inlet and outlet valves M-11 and M-12 and opening valve M-13 allows for the maintenance of evaporator 3.

[0041] The working process of this utility model: To avoid surge in the centrifugal compressor during low-load operation and to expand its operating range, the following technical measures are implemented: Compressor 1 is equipped with an IGV inlet guide vane suction regulating valve, which can further regulate compressor energy reduction during partial-load operation. A check valve 5 is designed at the discharge outlet of centrifugal compressor 1 to prevent reverse rotation during shutdown. A hot gas bypass unit PT is installed between the compressor 1 discharge pipe and the evaporator 3, consisting of a first hot gas bypass valve PT-1 and a second hot gas bypass valve PT-2. The first hot gas bypass valve PT-1 directly guides the compressor 1 discharge to the top vapor phase space of the evaporator 3, eliminating the influence of discharge back pressure during compressor start-up and shutdown. The second hot gas bypass valve PT-2 directly guides the high-temperature, high-pressure fluid after the compressor discharge check valve 5 to the bottom liquid phase space of the evaporator 3, effectively suppressing rapid temperature drops in chilled water and avoiding frequent start-ups and shutdowns. The large-capacity compressor motor cooling and inverter cooling adopt two-phase refrigerant cooling, which has a stronger cooling capacity than conventional refrigerant liquid cooling, water cooling, and air cooling. It also uses an electronic expansion valve for throttling to achieve accurate temperature control. Cooling functions are accomplished through the compressor motor cooling unit DJ and the compressor inverter cooling unit BP, respectively. Refrigerant cooling of the inverter provides better cooling performance than air cooling, results in a smaller housing size and lower noise, and avoids scale buildup and blockage in the water circuit compared to water cooling. To prevent liquid carryover during centrifugal compressor suction, an evaporator level gauge 8 is designed to effectively prevent liquid carryover during compressor suction by controlling the liquid level in the evaporator.

[0042] Evaporative condenser 2 employs a serpentine tube bundle heat exchanger, continuously bent and formed without butt welds, made of high-grade SUS316L stainless steel, offering excellent corrosion resistance. Its design incorporates co-directional air and water heat exchange, high-flow-rate spraying, and a large-capacity water tank to enhance anti-scaling performance. A large settling and separation space effectively reduces water drift. The evaporative condenser's structural layout has been changed from a conventional single-channel to a dual-channel layout, with the evaporative air cooler 2-a centrally located and the evaporative cooling coils 2-b symmetrically arranged on both sides of the condenser. The sprayed water and air exchange in a co-directional flow. The evaporative air cooler 2-a is a large-diameter, low-noise axial flow fan, centrally positioned to increase the unit's air intake area and water vapor separation space, thus reducing water drift. Evaporative cooling coil 2-b adopts a modular unit coil design. Its symmetrical arrangement structure increases the number of standard module coils. For evaporative cooling module unit coils composed of small-diameter heat exchange tubes, the number of heat exchange flow paths is increased, which can reduce refrigerant pressure drop and control the refrigerant mass flow rate to a more favorable heat exchange area.

[0043] A bypass branch is designed at the water-side inlet and outlet of evaporator 3, enabling the following application scenarios: Scenario 1: During the initial water system test and cleaning of the user's water system, water valves M-11 and M-12 can be closed to isolate evaporator 3 from the water circuit. By opening the bypass branch valve M-13, the internal heat exchanger water circuit is isolated, preventing debris from entering the heat exchanger and avoiding blockage or erosion damage to the heat exchange tubes, significantly improving the safety and reliability of the heat exchanger. Scenario 2: If the unit's circulating water flow is too high, exceeding the rated flow by more than 1.5 times, it can easily damage evaporator 3. By opening the bypass branch valve M-13 for bypass flow, protecting evaporator 3. Scenario 3: If evaporator 3 requires maintenance or antifreeze drainage, water valves M-11 and M-12 can be closed, and valve M-13 can be opened to isolate evaporator 3 from the operating water system, helping to improve operational reliability.

[0044] In the chilled water module unit M, variable frequency pumps can be used to improve operational adaptability and thus enhance pump operating efficiency. A standby pump design can be employed to enhance operational reliability.

[0045] It is understood that, for those skilled in the art, any equivalent substitutions or modifications to the technical solutions and inventive concepts of this utility model should fall within the protection scope of the appended claims.

Claims

1. A large-capacity evaporative cooling variable frequency air-suspension centrifugal chiller unit, characterized in that: It includes a compressor (1), a condenser (2), an evaporator (3), an economizer efficiency enhancement unit, a compressor motor cooling unit, a compressor inverter cooling unit, a hot gas bypass unit, a chilled water module unit, and piping and control circuits; The compressor (1) is an air-suspension variable frequency centrifugal compressor. The exhaust port (1-b) of the compressor (1) is connected to the inlet of the evaporative condenser (2). The outlet of the evaporative condenser (2) is connected to the tube side inlet of the evaporator (3). The tube side outlet of the evaporator (3) is connected to the suction port (1-a) of the compressor (1). The motor liquid supply interface (1j1) of the compressor (1) is connected to the outlet of the evaporative condenser (2) through the compressor motor cooling unit, and the motor cooling gas outlet interface (1j2) of the compressor (1) is connected to the top of the evaporator (3); the economizer efficiency enhancement unit includes an economizer plate heat exchanger (E-0), and the outlet liquid pipeline of the evaporative condenser (2) is provided with two paths connected to the economizer plate heat exchanger (E-0), one of which is provided with an economizer throttling device (E-1) and leads to the auxiliary channel inlet of the economizer plate heat exchanger (E-0), and the auxiliary channel outlet of the economizer efficiency enhancement unit is connected to the economizer interface (1j3) of the compressor (1); the other path leads to the main channel inlet of the economizer plate heat exchanger (E-0), and the main channel outlet of the economizer plate heat exchanger (E-0) is connected to the evaporator (3); The compressor inverter cooling unit is connected between the outlet liquid pipe of the evaporator (3) and the evaporative condenser (2). The hot gas bypass unit is connected between the exhaust port (1-b) and the evaporator (3). The chilled water module unit is connected to the water side inlet and outlet of the evaporator (3), and the chilled water module unit is connected to the inlet and outlet of the user end.

2. The large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit according to claim 1, characterized in that: The economizer efficiency enhancement unit also includes an economizer filter (E-2) and an electric valve (E-3). The economizer plate heat exchanger (E-0) is a subcooled plate heat exchanger. The economizer filter (E-2) is connected to the liquid outlet pipe of the evaporative condenser (2). The economizer filter (E-2) is connected to the inlet of the economizer throttling device (E-1). The outlet of the economizer throttling device (E-1) is connected to the inlet of the auxiliary channel of the economizer plate heat exchanger (E-0). The outlet of the auxiliary channel of the economizer plate heat exchanger (E-0) is connected to the economizer interface (1j3) through the electric valve (E-3). The main channel outlet of the economizer plate heat exchanger (E-0) is connected to the evaporator (3) in sequence through the maintenance valve (6), the dryer filter (7), and the throttling device (4).

3. The large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit according to claim 1, characterized in that: The compressor motor cooling unit includes a motor throttling device (DJ-1), a motor filter (DJ-2), and a motor maintenance valve (DJ-3) connected in sequence through pipelines. The inlet of the motor maintenance valve (DJ-3) is connected to the liquid outlet pipeline of the evaporative condenser (2). The motor throttling device (DJ-1) is connected to the motor liquid supply interface (1j1) of the compressor (1) and provides low-temperature two-phase refrigerant cooling to the motor of the compressor (1), so that the motor temperature of the compressor is less than 70°C during full-condition operation. The fluid after heat exchange returns to the evaporator (3) through the motor cooling outlet interface (1j2).

4. The large-capacity evaporative cooling variable frequency air-suspended centrifugal chiller unit according to claim 1, characterized in that: The compressor inverter cooling unit includes an inverter maintenance valve (BP-3), an inverter filter (BP-2), an inverter throttling device (BP-1), and an inverter cooler (BP-0) connected in sequence by pipelines. The inlet of the inverter maintenance valve (BP-3) is connected to the liquid outlet pipeline of the evaporative condenser (2). The inverter throttling device (BP-1) provides low-temperature two-phase refrigerant cooling to the compressor inverter module, so that the temperature of the compressor inverter module is less than 80°C under all operating conditions. The fluid after heat exchange flows back to the gas phase space above the evaporator (3) cylinder through the inverter cooler (BP-0).

5. The large-capacity evaporative cooling variable frequency air-suspended centrifugal chiller unit according to claim 1, characterized in that: An exhaust check valve (5) is installed on the connecting pipe between the exhaust port (1-b) of the compressor (1) and the evaporative condenser (2). The hot gas bypass unit has two branches. The first branch is connected between the exhaust port (1-b) and the exhaust check valve (5). Through the first hot gas bypass valve (PT-1) installed on the first branch, the high temperature and high pressure hot gas from the exhaust port (1-b) is directed to the gas phase space at the top of the evaporator (3). The second branch is connected behind the exhaust check valve (5). Through the second hot gas bypass valve (PT-2) installed on the second branch, the high temperature and high pressure hot gas from the compressor exhaust flowing through the exhaust check valve (5) is directed to the bottom liquid phase space of the evaporator (3).

6. The large-capacity evaporative cooling variable frequency air-suspended centrifugal chiller unit according to claim 1, characterized in that: The chilled water module unit includes a chilled water pump (M-1). One end of the chilled water pump (M-1) is connected in sequence to a filter (M-2), a first water circuit valve (M-10), an expansion tank (M-7), a safety valve (M-8), and a pressure gauge (M-17), and is connected to the user-side return water. The other end of the chilled water pump (M-1) is connected in sequence to a flexible connector (M-16), a check valve (M-3), an electronic descaling device (M-4), and a second water circuit valve (M-11), and is connected to the water-side inlet of the evaporator (3). The water-side outlet of the evaporator (3) is equipped with a third water circuit valve (M-12) and is connected to the user-side outlet water.

7. The large-capacity evaporative cooling variable frequency air-suspended centrifugal chiller unit according to claim 6, characterized in that: A flow switch (M-6) is connected to the second water circuit valve (M-11) and the third water circuit valve (M-12) via a bypass. The second water circuit valve (M-11) and the electronic descaling device (M-4) are connected to the user's outlet via a pipeline, and the pipeline is equipped with a fourth water circuit valve (M-13) and an automatic air vent valve (M-5). A bypass pipeline is provided between the filter (M-2) and the first water circuit valve (M-10), and a fifth water circuit valve (M-15) and an automatic water supply valve (M-9) are connected in parallel on the bypass pipeline, and a water supply port is provided. A drain valve (M-14) is provided between the chilled water pump (M-1) and the filter (M-2).

8. The large-capacity evaporative cooling variable frequency air suspension centrifugal chiller unit according to claim 1, characterized in that: The evaporative condenser (2) includes an evaporative air cooler (2-a) arranged in the center, evaporative cooling coils (2-b) arranged symmetrically on both sides of the evaporative condenser (2), and a spray water pump (2-c) connected to a spray head set above the evaporative cooling coils (2-b).

9. The large-capacity evaporative cooling variable frequency air-suspended centrifugal chiller unit according to claim 1, characterized in that: The compressor (1) is equipped with an IGV inlet guide vane intake regulating valve at its intake port (1-a).

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