Water chilling unit operating under extreme working condition

Abstract

The invention discloses a water chilling unit operating under extreme working conditions, which comprises a fan and a finned condenser at the upper part and a refrigerating unit at the lower part, and the refrigerating unit is provided with a refrigerant circulating system and a chilled water circulating system; the refrigerant circulating system comprises a compressor, a finned condenser, an electronic expansion valve and a shell and tube evaporator which are connected in sequence; the chilled water circulation system comprises a water pipe, a water pump and an evaporator which are connected in sequence; the electronic expansion valve is connected with the drying filter cartridge and the shell and tube evaporator, the drying filter cartridge is connected with the liquid storage tank, and the shell and tube evaporator is connected with the gas-liquid separator. According to the invention, PWM and stepless regulation multi-dimensional cooperative control are used, so that stable operation is realized when the energy efficiency in a wide temperature range is suddenly reduced; on the high-temperature side, the condensation fan adopts a stepless speed regulation technology; and the low-temperature side is switched into a PWM period adjusting mode.

Description

Technical Field

[0001] The present invention relates to the field of refrigeration technology, and in particular to a chiller operating under extreme working conditions. Background Art

[0002] Air-cooled chillers operate on the principle of vapor compression refrigeration, achieving a refrigeration cycle through the coordinated action of a compressor, air-cooled condenser, throttling device, and evaporator. When the unit operates the refrigeration cycle, the compressor adiabatically compresses the low-temperature, low-pressure gaseous refrigerant, outputting a high-temperature, high-pressure, high-temperature, high-pressure gas. The high-temperature refrigerant gas enters the air-cooled condenser, where, under forced convection heat transfer, it undergoes a gas-liquid phase transition and releases latent heat, transforming into a high-pressure, subcooled liquid refrigerant. The high-pressure liquid refrigerant flows through the throttling device, achieving adiabatic throttling, and forms a low-temperature gas at the outlet. The high-temperature gaseous refrigerant absorbs heat at an isobaric pressure within the evaporator, exchanges heat with chilled water, and is completely vaporized into a saturated gas before returning to the compressor suction port, forming a closed cycle. Existing technologies, such as an outdoor cabinet for electronic equipment with air cooling and heat dissipation resistant to harsh environments (CN119031669A), disclose an outdoor cabinet for electronic equipment with air cooling and heat dissipation resistant to harsh environments. The cabinet body adopts a skeleton structure, with the outer surface skin being a continuous sealed structure. The front and rear doors are hingedly mounted on the cabinet body and locked with door locks. Conductive sealing strips are installed between the door frame and the cabinet body for sealing. The front door of the cabinet body is a ventilation and heat dissipation area, while the rear door is a closed area. The ventilation and heat dissipation area and the closed area are separated by a back panel. Electronic equipment requiring heat dissipation are installed in the ventilation and heat dissipation area, while components not requiring heat dissipation are installed in the closed area. The ventilation and heat dissipation area has an air inlet at the bottom, and an air outlet is located above the cabinet body. This solves the problem that outdoor cabinets for electronic equipment must meet the requirements of open air cooling and heat dissipation and have good environmental adaptability.

[0003] Air-cooled screw chillers face severe challenges operating under extreme conditions such as large temperature swings throughout the year and rain, snow, wind, and sandstorms. When the ambient temperature varies significantly throughout the year, the condensing pressure rises sharply in high-temperature environments. This not only causes excessively high compressor exhaust temperatures, posing a risk of lubricant carbonization, but can also cause malfunctions on the control panel due to insufficient heat dissipation from electronic components. In low-temperature environments, a sudden increase in lubricant viscosity affects lubrication effectiveness, refrigerant migration can easily induce liquid hammer, and the evaporator copper tubes face the risk of frost heave and rupture. Low-temperature embrittlement of metal materials can also cause cracks in flange welds. Excessively low condensing pressure can also interfere with the traditional throttling device's adjustment based on the evaporator outlet superheat. Combined with the lag in the response of traditional PID control, this often causes the compressor to start and stop frequently or deviate from the high-efficiency operating zone for long periods, accelerating wear of core components.

[0004] The combined effects of rain, snow, and windy sandstorms further exacerbate the operational challenges of the units. Large particles such as sand and dust clog the gaps between the condenser fins, causing a drop in airflow and triggering high-pressure alarms. Heavy rainfall impacting the fins can cause aluminum foil to collapse and copper pipe welds to corrode and perforate. Rainwater infiltration can also cause the fan bearing lubrication to fail. Snow accumulation forms an insulating layer over the fins, reducing the heat transfer temperature difference. Repeated melting and freezing expansion can easily cause the windowed fin structure to fracture. Salt carried by windblown sand adheres to the fin surface, combining with condensate to form an electrolyte that accelerates electrochemical corrosion. Furthermore, dust intrusion into the electrical control cabinet can not only cause electrical component shorts but also increase contact resistance in the contactors. These systemic problems, caused by the combination of extreme temperature differences and severe weather, significantly increase the annual failure rate of the units and accelerate performance degradation. Therefore, it is urgent to develop unit design and operation methods specifically for these extreme operating conditions to overcome these challenges. Summary of the Invention

[0005] Purpose of the invention: In response to the deficiencies and defects of the prior art, the present invention provides a method for using a chiller operating under extreme working conditions, which uses PWM and stepless regulation multi-dimensional coordinated control to achieve stable operation when the condensing temperature changes suddenly in a wide temperature range; on the high-temperature side, the condensing fan adopts stepless speed regulation technology, and dynamically adjusts the speed according to the signal of the condensing pressure sensor. The fan runs at high speed to enhance heat dissipation, ensuring that the condensing temperature does not exceed the limit, the system operates stably and the pressure difference fluctuation is small, and at the same time, the refrigerant flow is compensated by the opening of the electronic expansion valve to avoid the compressor exhaust temperature exceeding the limit; in a low-temperature environment, the fan stepless speed regulation cannot maintain the condensing temperature. When the condensing temperature continues to drop and exceeds the limit, the system automatically switches to PWM cycle regulation mode, the fan frequency is reduced to the lowest speed, and enters the self-regulating cycle intermittent start and stop to maintain the condensing pressure to prevent the lubricating oil viscosity from being too high, and cooperates with the superheat closed-loop control of the electronic expansion valve and combines with the compressor slide valve regulation to achieve evaporator side antifreeze protection and precise cooling output.

[0006] Technical solution: The present invention provides a chiller that operates under extreme working conditions, characterized in that it includes a fan and a finned condenser in the upper part and a refrigeration unit in the lower part, and the refrigeration unit is provided with a refrigerant circulation system and a chilled water circulation system; the refrigerant circulation system includes a compressor, a finned condenser, an electronic expansion valve and a shell and tube evaporator connected in sequence; the chilled water circulation system includes a water pipe, a water pump and an evaporator connected in sequence; the electronic expansion valve is connected to a drying filter cartridge and a shell and tube evaporator, the drying filter cartridge is connected to a liquid storage tank, and the shell and tube evaporator is connected to a gas-liquid separator.

[0007] The air inlet side of the finned condenser is provided with a grid, which is a V-shaped dustproof grid.

[0008] The water pipes of the chilled water circulation system are connected to an external water supply system.

[0009] The fin-type condenser is provided with a water inlet, a water outlet and a water flow switch.

[0010] The side of the finned condenser is provided with shutters.

[0011] The chiller operating under extreme working conditions of the present invention is characterized in that: in the refrigerant cycle, the low-temperature and low-pressure gaseous refrigerant first enters the compressor, is compressed into a high-temperature and high-pressure gas through rotor meshing, and then enters the finned condenser, where the fan drives the ambient air to force convection to dissipate heat, causing the refrigerant to condense into a medium-temperature and high-pressure liquid; when the liquid refrigerant flows through the electronic expansion valve, the opening is adjusted to achieve adiabatic expansion, forming a low-temperature and low-pressure gas-liquid two-phase flow, entering the shell and tube evaporator to absorb the heat of the chilled water and completely vaporize, and finally returning to the compressor to complete the cycle.

[0012] The oil circuit system operates synchronously. The lubricating oil discharged from the compressor is captured by the oil separator, cooled by the oil cooler, and then recirculated into the compressor bearings and rotor cavity for lubrication, ensuring low-wear operation of the moving parts.

[0013] In the chilled water cycle, chilled water pumped into the system from the user meter first enters the buffer water tank. When the buffer water tank is filled to a set amount, room-temperature chilled water flows into the evaporator to exchange heat with the low-temperature refrigerant. After the chilled water temperature drops to the required range, it is delivered to the user-end equipment to absorb heat. After the temperature rises, the return water is filtered and purified before re-entering the evaporator cycle. The system regulates the water flow to ensure that the heat exchange temperature difference within the evaporator is within a reasonable range to avoid the risk of freezing. The chiller unit operating under extreme working conditions of the present invention is characterized by adopting a variable frequency regulation mode and a PMW regulation mode. During operation, it detects the outdoor dry-bulb temperature and condensing temperature, automatically determines whether the switching conditions are met, and automatically switches between the variable frequency regulation mode and the PMW regulation mode.

[0014] In high-temperature environments, the fan automatically switches to variable frequency regulation mode. The fan speed is dynamically adjusted according to the signal from the condensing pressure sensor, running at high speed to enhance heat dissipation, ensuring stable condensing temperature and small pressure difference fluctuations. At the same time, the refrigerant flow is compensated by the opening of the electronic expansion valve to avoid exceeding the compressor exhaust temperature limit.

[0015] In low-temperature environments, the system automatically switches to PWM cycle adjustment mode. At this time, the fan frequency has been adjusted to the lowest speed, and the fan is switched to PWM adjustment, automatically switching to an initial duty cycle of 0.8, that is, it runs for 4 minutes and then stops for 1 minute. If the condensing pressure still drops according to this cycle, the duty cycle will be reduced; otherwise, the duty cycle will be increased. In conjunction with the superheat closed-loop control of the electronic expansion valve and the adjustment of the compressor slide valve, the condensing pressure is maintained to prevent the lubricating oil viscosity from being too high, thereby achieving antifreeze protection on the evaporator side and accurate cooling output.

[0016] The chilled water pump does not stop when the unit is in standby mode; after shutdown, the chilled water pump and cooling fan are shut down with a delay.

[0017] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: 1) High efficiency and energy saving: The present invention integrates variable frequency drive, electronic expansion valve and compressor load coordinated control, based on multi-sensor data fusion and adaptive algorithm, automatically identifies abnormal working conditions, switches to standby strategy to ensure continuous operation, quickly responds to load fluctuations, reduces energy consumption peak-valley difference, and maintains optimal efficiency under all working conditions. 2) Reliable operation: The system has built-in anti-freeze, anti-overheating and anti-corrosion functions for extreme conditions, reducing the risk of system failure. By strengthening the speed regulation range of the condensing fan and the selection of low-temperature resistant materials, a two-way balance between high-temperature heat dissipation and low-temperature antifreeze is achieved, which can adapt to various complex and changeable operating environments and ensure stable operation and efficient cooling effect of the equipment.

[0018] This invention incorporates a V-shaped dust screen on the condenser's air inlet side, separating PM50+ particles through inertial collision and featuring a quick-release mechanism for easy cleaning. A rain and snow diversion system is installed on the top and a drainage trough at the bottom to direct runoff away from the fin area. The screen and diversion device are epoxy-coated for resistance to salt spray corrosion, reducing maintenance frequency and extending fin life. The system integrates a low-temperature lubricating oil heater and refrigerant migration suppression logic, supplemented by a liquid storage tank and gas-liquid separator. Ultimately, an intelligent controller integrates multi-parameter prediction algorithms, including ambient temperature, pressure, and flow, to meet the reliable cooling needs of harsh environments such as deserts and polar regions. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of the present invention;

[0020] Figure 2 It is an internal system diagram of the present invention;

[0021] In the figure, 1 is a fan; 2 is a shutter; 3 is a gas-liquid separator; 4 is a grid; 5 is a water outlet; 6 is a shell and tube evaporator; 7 is a water inlet; 8 is a compressor; 9 is a liquid storage tank; 10 is a drying filter cartridge; and 11 is a finned condenser. DETAILED DESCRIPTION

[0022] The technical solution of the present invention is further described below in conjunction with the accompanying drawings and specific implementation methods.

[0023] The chiller unit of the present invention, which operates under extreme working conditions, includes a fan 1 and a finned condenser 11 in the upper portion, and a refrigeration unit in the lower portion. The refrigeration unit is provided with a refrigerant circulation system and a chilled water circulation system. The refrigerant circulation system includes a compressor 8, a finned condenser 11, an electronic expansion valve, and a shell-and-tube evaporator 6 connected in sequence. The chilled water circulation system includes a water pipe, a water pump, and an evaporator connected in sequence. The electronic expansion valve is connected to a drying filter cartridge 10 and a shell-and-tube evaporator 6, the drying filter cartridge 10 is connected to a liquid storage tank 9, and the shell-and-tube evaporator 6 is connected to a gas-liquid separator 3. A grid 4 is provided on the air inlet side of the finned condenser 11, and the grid 4 is a V-shaped dustproof grid. The water pipe of the chilled water circulation system is connected to an external water supply system. The finned condenser 11 is provided with a water inlet 7, a water outlet 5, and a water flow switch. A louver 2 is provided on the side of the finned condenser 11.

[0024] In the chiller operating under extreme working conditions of the present invention, in the refrigerant cycle, the low-temperature and low-pressure gaseous refrigerant first enters the compressor 8, is compressed into a high-temperature and high-pressure gas through rotor meshing, and then enters the finned condenser 11. The fan 1 drives the ambient air to force convection heat dissipation, so that the refrigerant is condensed into a medium-temperature and high-pressure liquid; when the liquid refrigerant flows through the electronic expansion valve, it realizes adiabatic expansion through opening adjustment, forming a low-temperature and low-pressure gas-liquid two-phase flow, enters the shell and tube evaporator 6 to absorb the heat of the chilled water and is completely vaporized, and finally returns to the compressor 8 to complete the cycle.

[0025] The oil circuit system operates synchronously. The lubricating oil discharged from the compressor 8 is captured by the oil separator, cooled by the oil cooler, and then recirculated into the compressor bearings and rotor cavity for lubrication, ensuring low-wear operation of the moving parts.

[0026] In the chilled water cycle, chilled water at room temperature is driven by a water pump, flows through the evaporator, and exchanges heat with the low-temperature refrigerant to reduce its temperature to the required range. It is then transported to the user-end equipment to absorb heat. The return water after the temperature rises is filtered and purified before re-entering the evaporator cycle; the system ensures that the heat exchange temperature difference in the evaporator is within a reasonable range by adjusting the water flow rate to avoid the risk of freezing.

[0027] The chiller operating under extreme working conditions of the present invention adopts a variable frequency regulation mode and a PMW regulation mode, detects the outdoor dry bulb temperature and the condensing temperature during operation, automatically determines whether the switching conditions are met, and automatically switches between the variable frequency regulation mode and the PMW regulation mode.

[0028] In high temperature environments, the fan 1 automatically switches to variable frequency regulation mode. The fan 1 dynamically adjusts its speed according to the condensing pressure sensor signal and runs at high speed to enhance heat dissipation, ensuring stable condensing temperature and small pressure difference fluctuations. At the same time, the refrigerant flow is compensated by the opening of the electronic expansion valve to prevent the exhaust temperature of the compressor 8 from exceeding the limit.

[0029] In low-temperature environments, the system automatically switches to PWM cycle adjustment mode. When the fan frequency is adjusted to the lowest speed, fan 1 switches to PWM adjustment and automatically switches to an initial duty cycle of 0.8, i.e., it runs for 4 minutes and then stops for 1 minute. If the condensing pressure still drops according to this cycle, the duty cycle will be reduced; otherwise, the duty cycle will be increased. In conjunction with the superheat closed-loop control of the electronic expansion valve and the adjustment of the compressor 8 slide valve, the condensing pressure is maintained to prevent the lubricating oil viscosity from being too high, thus achieving antifreeze protection on the evaporator side and accurate cooling output.

[0030] The chilled water pump does not stop when the unit is in standby mode; after shutdown, the chilled water pump and cooling fan are shut down with a delay.

[0031] The present invention is 1) highly efficient and energy-saving: it integrates variable frequency drive, electronic expansion valve and compressor load coordinated control, based on multi-sensor data fusion and adaptive algorithm, automatically identifies abnormal operating conditions, switches to backup strategies to ensure continuous operation, quickly responds to load fluctuations, reduces energy consumption peaks and valleys, and maintains optimal efficiency under all operating conditions. 2) Reliable operation: the system has built-in antifreeze, anti-overheating and anti-corrosion functions for extreme conditions, reducing the risk of system failure. By strengthening the condensing fan speed regulation range and selecting low-temperature resistant materials, it achieves a two-way balance between high-temperature heat dissipation and low-temperature antifreeze, can adapt to various complex and changing operating environments, and ensure stable operation and efficient cooling effect of the equipment.

[0032] This invention incorporates a V-shaped dust screen on the condenser's air inlet side, separating PM50+ particles through inertial collision and featuring a quick-release mechanism for easy cleaning. A rain and snow diversion system is installed on the top and a drainage trough at the bottom to direct runoff away from the fin area. The screen and diversion device are epoxy-coated for resistance to salt spray corrosion, reducing maintenance frequency and extending fin life. The system integrates a low-temperature lubricating oil heater and refrigerant migration suppression logic, supplemented by a liquid storage tank and gas-liquid separator. Ultimately, an intelligent controller integrates multi-parameter prediction algorithms, including ambient temperature, pressure, and flow, to meet the reliable cooling needs of harsh environments such as deserts and polar regions.

Claims

1. A chiller operating under extreme working conditions, characterized by: The invention comprises a fan (1) in the upper part, a finned condenser (11) and a refrigeration unit in the lower part, wherein the refrigeration unit is provided with a refrigerant circulation system and a chilled water circulation system; the refrigerant circulation system comprises a compressor (8), a finned condenser (11), an electronic expansion valve and a shell-and-tube evaporator (6) connected in sequence; the chilled water circulation system comprises a water pipe, a water pump and an evaporator connected in sequence; the electronic expansion valve is connected to a drying filter cartridge (10) and a shell-and-tube evaporator (6); the drying filter cartridge (10) is connected to a liquid storage tank (9); and the shell-and-tube evaporator (6) is connected to a gas-liquid separator (3).

2. The chiller operating under extreme working conditions according to claim 1, characterized in that: The air inlet side of the finned condenser (11) is provided with a grid (4), and the grid (4) is a V-shaped dustproof grid.

3. The chiller operating under extreme working conditions according to claim 1, characterized in that: The water pipes of the chilled water circulation system are connected to an external water supply system.

4. The chiller operating under extreme working conditions according to claim 1, characterized in that: The finned condenser (11) is provided with a water inlet (7), a water outlet (5) and a water flow switch.

5. The chiller operating under extreme working conditions according to claim 1, characterized in that: The fin-type condenser (11) is provided with a shutter (2) on the side.

6. A chiller operating under extreme working conditions according to any one of claims 1 to 5, characterized in that: In the refrigerant cycle, the low-temperature, low-pressure gaseous refrigerant first enters the compressor (8), is compressed into a high-temperature, high-pressure gas by the rotor meshing, and then enters the finned condenser (11). The fan (1) drives the ambient air to force convection heat dissipation, so that the refrigerant is condensed into a medium-temperature, high-pressure liquid; when the liquid refrigerant flows through the electronic expansion valve, it is adiabatically expanded by adjusting the opening, forming a low-temperature, low-pressure gas-liquid two-phase flow, and enters the shell and tube evaporator (6) to absorb the heat of the chilled water and completely vaporize, and finally returns to the compressor (8) to complete the cycle.

7. The chiller operating under extreme working conditions according to claim 6, characterized in that: The oil circuit system operates synchronously. The lubricating oil discharged from the compressor (8) is collected by the oil separator, cooled by the oil cooler, and then recirculated and injected into the compressor bearings and rotor cavity for lubrication, ensuring low-wear operation of the moving parts.

8. The chiller operating under extreme working conditions according to any one of claims 1 to 5, characterized in that: In the chilled water cycle, chilled water at room temperature is driven by a water pump, flows through the evaporator, and exchanges heat with the low-temperature refrigerant to reduce its temperature to the required range. It is then transported to the user-end equipment to absorb heat. The return water after the temperature rises is filtered and purified before re-entering the evaporator cycle; the system ensures that the heat exchange temperature difference in the evaporator is within a reasonable range by adjusting the water flow rate to avoid the risk of freezing.

9. The chiller operating under extreme working conditions according to any one of claims 1 to 5, characterized in that: It adopts variable frequency regulation mode and PMW regulation mode, detects outdoor dry bulb temperature and condensing temperature during operation, automatically determines whether the switching conditions are met, and automatically switches between variable frequency regulation mode and PMW regulation mode.

10. The chiller operating under extreme working conditions according to claim 9, characterized in that: In a high temperature environment, the variable frequency adjustment mode is automatically switched, and the fan (1) dynamically adjusts the speed according to the signal of the condensing pressure sensor, and runs at high speed to enhance heat dissipation, ensuring that the condensing temperature is stable and the pressure difference fluctuation is small. At the same time, the refrigerant flow is compensated by the opening of the electronic expansion valve to avoid the exhaust temperature of the compressor (8) exceeding the limit; In a low-temperature environment, the PWM cycle adjustment mode is automatically switched. At this time, the fan frequency has been adjusted to the lowest speed. The fan (1) is changed to PWM adjustment and automatically switches to an initial duty cycle of 0.8, that is, it runs for 4 minutes and then stops for 1 minute. If the condensing pressure still drops according to this cycle, the duty cycle becomes smaller; On the contrary, the duty cycle becomes larger, and the closed-loop control of the superheat of the electronic expansion valve is combined with the adjustment of the compressor (8) slide valve to maintain the condensing pressure to prevent the viscosity of the lubricating oil from being too high, thereby achieving antifreeze protection on the evaporator side and accurate cooling output; The chilled water pump does not stop when the unit is in standby mode; after shutdown, the chilled water pump and cooling fan are shut down with a delay.

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