A screw type air-cooled chiller and operation method thereof

Abstract

The present invention relates to the field of chillers, and discloses a screw air-cooled chiller and an operation method, including setting a target cold water temperature and environmental adaptation parameters, starting a compressor and a fan, and gradually increasing the operating power; adjusting the operating frequency of the compressor and the fan speed according to the actual load demand, monitoring the evaporation temperature and the condensation temperature in real time, and optimizing the throttling device opening; starting and stopping the compressor according to the load demand in a multi-compressor system, and reducing the fan speed and the compressor power at low ambient temperature; periodically defrosting or adjusting the fan speed when running at low load or at low ambient temperature, regularly cleaning the evaporator and condenser, and removing the accumulated scale; monitoring the fault state in real time through a sensor and an electronic control system, and executing automatic shutdown, load reduction or sending an alarm according to the fault level. The present invention has the advantage of ensuring the long-term stable operation of the equipment.

Description

Technical Field

[0001] The invention relates to the field of chillers, and in particular to a screw-type air-cooled chiller and an operating method thereof. Background Art

[0002] With the continuous advancement of industrialization, refrigeration technology has been widely used in many fields, especially in industrial production and building air conditioning that require large-scale temperature control. As an important refrigeration equipment, chillers are widely used in industrial, commercial and civil fields. Its main function is to reduce the water temperature through the circulation of refrigerant and transport the cooling water to the system or equipment that needs to be cooled.

[0003] Traditional chillers generally include core components such as compressors, evaporators, condensers and expansion valves. With the continuous advancement of technology, the design and operation of various types of chillers are constantly innovating. Among chillers, screw compressors have gradually become efficient and reliable refrigeration equipment due to their unique working principles and advantages. Screw compressors are based on the principle of relative rotation of screw rotors and can provide more stable and efficient compression performance. Compared with other types of compressors, screw compressors have higher energy efficiency ratios and lower noise levels, which makes them widely used in large-scale commercial and industrial applications. By precisely controlling the speed of the screw rotor, screw chillers can adapt to different load requirements, thereby improving energy utilization efficiency.

[0004] Air-cooled chillers use air as a cooling medium and utilize an air-cooled condenser to remove heat from the refrigerant. They do not rely on water sources and are suitable for areas with poor water sources. Compared with water-cooled chillers, air-cooled chillers have a simpler structure and lower installation and maintenance costs, making them particularly suitable for air conditioning systems in small and medium-sized buildings and factories.

[0005] However, with the increasing demand for chillers, how to improve the operating efficiency of screw air-cooled chillers, reduce energy consumption, and extend service life has become an urgent problem to be solved. Therefore, it is necessary to design a screw air-cooled chiller and an operating method that can ensure long-term stable operation of the equipment. Summary of the invention

[0006] 1. Technical issues to be solved

[0007] In view of the deficiencies in the prior art, the present invention provides a screw-type air-cooled chiller and an operating method, which have the advantages of ensuring long-term stable operation of the equipment and solve the problems in the above-mentioned background technology.

[0008] (II) Technical solution

[0009] In order to achieve the above-mentioned purpose of improving its comprehensive performance and ensuring the long-term stable operation of the equipment, the present invention provides the following technical solutions: a screw air-cooled chiller, comprising a screw compressor, a condenser, an evaporator, a throttling device, a refrigerant, an electronic control system and auxiliary equipment;

[0010] The screw compressor is a core component responsible for compressing the refrigerant and providing cooling output;

[0011] The condenser adopts a finned heat exchanger and an axial flow fan to dissipate heat through air cooling;

[0012] The evaporator exchanges heat with the cooling medium to cool the cold water;

[0013] The throttling device is a thermal expansion valve, which is used to control the refrigerant flow and reduce the pressure;

[0014] The refrigerant is R134a environmentally friendly refrigerant;

[0015] The electric control system includes a PLC controller, a sensor and a frequency converter, which are used to monitor operating parameters and perform intelligent control;

[0016] The auxiliary equipment includes a liquid receiver, an oil separator and a drying filter, which are used to assist refrigerant circulation and system protection.

[0017] A method for operating a screw air-cooled chiller comprises the following steps:

[0018] S1: Set the target cold water temperature and environmental adaptation parameters, turn on the compressor and fan, and gradually increase the operating power;

[0019] Preferably, S1 further includes using a low-speed operation mode to gradually increase the cooling output, gradually increase the compressor speed, and adjust the fan speed at the same time, and adjust the compressor speed through a frequency converter. The power is proportional to the speed. The power calculation formula is:

[0020] In the formula, P is the compressor power, Q is the cooling capacity, and COP is the coefficient of performance. The required power output is calculated based on the cooling capacity change and COP value of the system. Based on the operating data, the deviation between the target power and the actual power is calculated, and the compressor output is automatically adjusted;

[0021] By adjusting the fan speed, the heat dissipation efficiency can be maintained according to the change of ambient temperature. The wind speed sensor and current sensor are used to monitor the operating status of the fan and compare it with the set target wind speed to adjust the fan speed in real time. The relationship between the fan speed and the ambient temperature is calculated as follows:

[0022] Where N is the fan speed, Nmax is the maximum speed, T ambient is the current ambient temperature, T max and T min They are the maximum and minimum values ​​of the fan operating temperature range respectively.

[0023] S2: Adjust the operating frequency of the compressor and the fan speed according to the actual load demand, monitor the evaporation temperature and condensation temperature in real time, and optimize the opening of the throttling device;

[0024] Preferably, S2 further includes calculating the actual load of the system by real-time monitoring of the cold water outlet temperature, ambient temperature and flow rate, and the load demand calculation formula is: Q = m*C p *(T inlet -T outlet )

[0025] In the formula, Q is the cooling capacity, m is the cooling water flow rate, C p is the specific heat capacity of water, T inlet and T outlet are the cold water inlet and outlet temperatures respectively;

[0026] The throttling device controls the flow and pressure of the refrigerant, affecting the evaporation temperature and condensation temperature. When the evaporation temperature is too high or too low, the expansion valve opening is adjusted.

[0027] S3: In a multi-compressor system, the compressors are started and stopped according to load demand, and the fan speed and compressor power are reduced when the ambient temperature is low;

[0028] Preferably, S3 further includes that in a multi-compressor system, the system dynamically adjusts the equipment operating status by real-time monitoring of load demand and ambient temperature. When the load demand is low, the system will gradually stop some compressors according to the load prediction model. The whole process realizes the coordinated optimization of fans and compressors through real-time feedback of precise temperature, pressure and flow data combined with intelligent control algorithms.

[0029] S4: When running at low load or at low ambient temperature, periodically defrost or adjust the fan speed, clean the evaporator and condenser regularly, and remove accumulated scale;

[0030] Preferably, S4 further includes that when the system is running at low load or the ambient temperature is low, the system optimizes the operating efficiency by periodically defrosting or adjusting the fan speed. The defrosting process is usually automatically controlled according to the evaporation temperature or cycle setting, and the frost layer on the evaporator surface is melted by reverse operation or stopping the compressor.

[0031] S5: Real-time monitoring of fault status through sensors and electronic control systems, automatic shutdown, load reduction or alarm transmission according to the fault level.

[0032] Preferably, the S5 further includes continuously monitoring the operating status of the equipment by arranging multiple sensors in the system and combining the real-time monitoring function of the electronic control system. When the system detects an abnormality, the electronic control system will automatically execute corresponding protection measures according to the type and severity of the fault. When the fault level is high, the electronic control system will execute an automatic shutdown procedure, quickly cut off the power supply and start the backup system. The system will transmit the fault information to the monitoring platform or the operator's mobile device in real time through the networking function, and issue an alarm notification. The fault level is evaluated based on the comparison of the real-time data of the equipment with the preset threshold, and the trend is analyzed with the help of intelligent algorithms to predict potential fault risks.

[0033] (III) Beneficial effects

[0034] Compared with the prior art, the present invention provides a screw-type air-cooled chiller and an operating method, which have the following beneficial effects:

[0035] The present invention adjusts the operating frequency and fan speed of the compressor according to the actual load demand, monitors the evaporation temperature and condensation temperature in real time, and optimizes the throttling device opening; in a system of multiple compressors, starts and stops the compressor according to the load demand, and reduces the fan speed and compressor power when the ambient temperature is low; when running at low load or the ambient temperature is low, periodic defrosting or adjusting the fan speed, regularly cleaning the evaporator and condenser, and removing the accumulated scale; the fault status is monitored in real time through sensors and electronic control systems, and automatic shutdown, load reduction or alarm is executed according to the fault level. It has the advantage of ensuring the long-term stable operation of the equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 Schematic diagram of the method of the present invention. DETAILED DESCRIPTION

[0037] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0038] Example 1

[0039] The present invention provides a technical solution: an operation method of a screw air-cooled chiller, comprising the following steps:

[0040] S1: Set the target cold water temperature and environmental adaptation parameters, turn on the compressor and fan, and gradually increase the operating power;

[0041] Set the target chilled water temperature according to the application requirements, for example, building air conditioning or industrial cooling. The target chilled water temperature is generally set in the range of 7°C-12°C, depending on the actual application. Monitor the chilled water temperature in real time through a temperature sensor and set the chilled water temperature error tolerance. Set the adaptability range of the external ambient temperature, usually 20°C-45°C, which is the ambient temperature range in which the air-cooled chiller can operate efficiently. For lower ambient temperatures, the load of the fan and compressor will be reduced accordingly. Use ambient temperature sensors for real-time monitoring, set maximum and minimum ambient temperature thresholds, and automatically adjust the operation strategy. Dynamically adjust the device output by monitoring the system load. Set the load response strategy according to the changes in chilled water demand. Monitor the chilled water temperature through a temperature sensor, use pressure sensors and flow sensors to evaluate the cooling load, and adjust it according to the difference between the set load and the actual value.

[0042] After setting the target chilled water temperature and load demand, start the compressor and fan. First, use the low-speed operation mode to gradually increase the cooling output to avoid sudden load changes. Gradually increase the compressor speed, for example from 30%-100%, while adjusting the fan speed to keep it within the error range of the target chilled water temperature. The power increase of the compressor should be dynamically adjusted according to the load demand and temperature changes. For example, when the load is low, the compressor operating power can be maintained at a lower value, such as 30%-50%, while increasing the power output when the load is high. The speed of the compressor is adjusted by the inverter, and the power is proportional to the speed, ensuring the optimization of energy efficiency under different load conditions. Power calculation formula:

[0043] In the formula, P is the compressor power, Q is the cooling capacity, and COP is the coefficient of performance. The required power output is calculated based on the cooling capacity change and COP value of the system. Based on the operating data, the deviation between the target power and the actual power is calculated, and the compressor output is automatically adjusted.

[0044] The speed of the fan directly affects the heat exchange efficiency of the condenser. By adjusting the fan speed, the best heat dissipation efficiency can be maintained according to the changes in ambient temperature, such as increasing the speed at high temperatures and reducing the speed at low temperatures. Use wind speed sensors and current sensors to monitor the operating status of the fan, compare it with the set target wind speed, and adjust the fan speed in real time.

[0045] The relationship between fan speed and ambient temperature is calculated by the formula:

[0046] Where N is the fan speed, N max is the maximum speed, T ambient is the current ambient temperature, T max and T min They are the maximum and minimum values ​​of the fan operating temperature range respectively.

[0047] S2: Adjust the operating frequency of the compressor and the fan speed according to the actual load demand, monitor the evaporation temperature and condensation temperature in real time, and optimize the opening of the throttling device;

[0048] The operating frequency of the compressor is directly related to the load demand. When the load is low, the speed of the compressor can be reduced to reduce energy consumption; when the load is high, the speed can be increased to provide more cooling capacity. The actual load of the system is calculated by real-time monitoring of the cold water outlet temperature, ambient temperature and flow rate. Load demand calculation formula: Q = m*C p *(T inlet -T outlet )

[0049] In the formula, Q is the cooling capacity, m is the cooling water flow rate, C p is the specific heat capacity of water, T inlet and T outlet are the cold water inlet and outlet temperatures respectively;

[0050] The throttling device controls the flow and pressure of the refrigerant, affecting the evaporation temperature and condensation temperature. Optimizing the opening of the throttling device can effectively adjust the cooling capacity and energy efficiency of the system. When the evaporation temperature is too high or too low, adjust the expansion valve opening. The opening of the throttling device directly affects the efficiency and energy efficiency of the refrigeration system. Too large an opening may cause the evaporation temperature to be too low and the refrigeration efficiency to be reduced; while too small an opening may cause the evaporation temperature to be too high, affecting the cooling capacity.

[0051] S3: In a multi-compressor system, the compressors are started and stopped according to load demand, and the fan speed and compressor power are reduced when the ambient temperature is low;

[0052] In a multi-compressor system, the system dynamically adjusts the operating status of the equipment by monitoring the load demand and ambient temperature in real time. When the load demand is low, the system will gradually stop some compressors according to the load forecast model to avoid excessive operation and energy waste. Only when the load demand increases will more compressors be enabled to ensure stable cooling output. At low ambient temperatures, the condensing temperature is low, so the heat dissipation efficiency of the fan is improved. The system reduces unnecessary energy consumption by reducing the fan speed. At the same time, the load of the compressor is also reduced accordingly. The compressor power output can be reduced by adjusting the inverter, thereby saving electricity and extending the service life of the equipment. The entire process realizes the coordinated optimization of the fan and the compressor through real-time feedback of precise temperature, pressure, flow and other data, combined with intelligent control algorithms, to ensure that the system always operates in the best state under different load and environmental conditions, maximize energy efficiency, reduce the risk of failure and extend the life cycle of the equipment.

[0053] S4: When running at low load or at low ambient temperature, periodically defrost or adjust the fan speed, clean the evaporator and condenser regularly, and remove accumulated scale;

[0054] When the system is running at low load or the ambient temperature is low, the system optimizes the operating efficiency by periodically defrosting or adjusting the fan speed to avoid the decrease of heat exchange efficiency due to the accumulation of frost on the evaporator surface. The defrosting process is usually automatically controlled according to the evaporation temperature or cycle setting. The frost layer on the evaporator surface is melted by reversing or stopping the compressor to restore the heat exchange efficiency. In addition, the system will regularly adjust the fan speed to ensure uniform air flow and avoid excessive fan work or unnecessary energy consumption caused by low ambient temperature. During long-term operation, scale or other contaminants may accumulate on the surface of the evaporator and condenser, which will affect the heat exchange performance. Therefore, these components must be cleaned regularly, usually by chemical cleaning or high-pressure water flow to remove deposits and ensure that the heat exchange efficiency is not affected. These maintenance and adjustment measures help to improve the system's operating stability, reduce the occurrence of failures, extend the service life of the equipment, and optimize energy use, especially under low load and low ambient temperature conditions, to ensure that the system always maintains an efficient and stable working state.

[0055] S5: Real-time monitoring of fault status through sensors and electronic control systems, automatic shutdown, load reduction or alarm transmission according to the fault level.

[0056] By arranging a variety of sensors in the system and combining them with the real-time monitoring function of the electronic control system, the operating status of the equipment can be continuously monitored. These sensors can accurately capture the key parameters of the equipment and promptly identify potential fault signs, such as excessive temperature, abnormal pressure fluctuations, or excessive vibration. When the system detects an abnormality, the electronic control system will automatically perform corresponding protection measures according to the type and severity of the fault. For example, when the fault level is low, the system may temporarily relieve the pressure by adjusting the equipment load or fan speed to avoid system overload; when the fault level is high, the electronic control system will execute an automatic shutdown procedure, quickly cut off the power supply and start the backup system to ensure the safe operation of the equipment. At the same time, the system will transmit the fault information to the monitoring platform or the operator's mobile device in real time through the networking function, and issue an alarm notification so that manual intervention measures can be taken in time. The assessment of the fault level is usually based on the comparison of the real-time data of the equipment with the preset threshold, and the trend is analyzed with the help of intelligent algorithms to predict the potential fault risk. Through this automated and intelligent fault diagnosis and response mechanism, the system can respond in the shortest time, reduce downtime, reduce maintenance costs, and improve the reliability and operation stability of the equipment.

[0057] It should be noted that, in this article, relational terms such as first and second, etc. are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Moreover, the terms "include", "comprise" or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, article or device.

[0058] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A screw type air-cooled chiller, characterized in that: Including screw compressor, condenser, evaporator, throttling device, refrigerant, electronic control system and auxiliary equipment; The screw compressor is a core component responsible for compressing the refrigerant and providing cooling output; The condenser adopts a finned heat exchanger and an axial flow fan to dissipate heat through air cooling; The evaporator exchanges heat with the cooling medium to cool the cold water; The throttling device is a thermal expansion valve, which is used to control the refrigerant flow and reduce the pressure; The refrigerant is R134a environmentally friendly refrigerant; The electric control system includes a PLC controller, a sensor and a frequency converter, which are used to monitor operating parameters and perform intelligent control; The auxiliary equipment includes a liquid receiver, an oil separator and a drying filter, which are used to assist refrigerant circulation and system protection.

2. The method for operating a screw air-cooled chiller according to claim 1, characterized in that: The following steps are involved: S1: Set the target cold water temperature and environmental adaptation parameters, turn on the compressor and fan, and gradually increase the operating power; S2: Adjust the operating frequency of the compressor and the fan speed according to the actual load demand, monitor the evaporation temperature and condensation temperature in real time, and optimize the opening of the throttling device; S3: In a multi-compressor system, the compressors are started and stopped according to load demand, and the fan speed and compressor power are reduced when the ambient temperature is low; S4: When running at low load or at low ambient temperature, periodically defrost or adjust the fan speed, clean the evaporator and condenser regularly, and remove accumulated scale; S5: Real-time monitoring of fault status through sensors and electronic control systems, automatic shutdown, load reduction or alarm transmission according to the fault level.

3. The operating method of a screw air-cooled chiller according to claim 1, characterized in that: The S1 further includes using a low-speed operation mode to gradually increase the cooling output, gradually increase the compressor speed, and adjust the fan speed at the same time. The compressor speed is adjusted by the inverter. The power is proportional to the speed. The power calculation formula is: In the formula, P is the compressor power, Q is the cooling capacity, and COP is the coefficient of performance. The required power output is calculated based on the cooling capacity change and COP value of the system. Calculate the deviation between target power and actual power based on operating data and automatically adjust compressor output; By adjusting the fan speed, the heat dissipation efficiency can be maintained according to the change of ambient temperature. The wind speed sensor and current sensor are used to monitor the operating status of the fan and compare it with the set target wind speed to adjust the fan speed in real time. The relationship between the fan speed and the ambient temperature is calculated as follows: Where N is the fan speed, N max is the maximum speed, T ambient is the current ambient temperature, T max and T min They are the maximum and minimum values ​​of the fan operating temperature range respectively.

4. The method for operating a screw-type air-cooled chiller according to claim 1, characterized in that: The S2 further includes calculating the actual load of the system by real-time monitoring of the cold water outlet temperature, ambient temperature and flow rate. The load demand calculation formula is: Q = m*C p *(T inlet -T outlet ) In the formula, Q is the cooling capacity, m is the cooling water flow rate, C p is the specific heat capacity of water, T inlet and T outlet are the cold water inlet and outlet temperatures respectively; The throttling device controls the flow and pressure of the refrigerant, affecting the evaporation temperature and condensation temperature. When the evaporation temperature is too high or too low, the expansion valve opening is adjusted.

5. The method for operating a screw air-cooled chiller according to claim 1, characterized in that: The S3 further includes that in a multi-compressor system, the system dynamically adjusts the equipment operating status by real-time monitoring of load demand and ambient temperature. When the load demand is low, the system will gradually stop some compressors according to the load prediction model. The entire process realizes the coordinated optimization of fans and compressors through real-time feedback of precise temperature, pressure, and flow data combined with intelligent control algorithms.

6. The method for operating a screw air-cooled chiller according to claim 1, characterized in that: The S4 further includes that when the system is running at low load or the ambient temperature is low, the system optimizes the operating efficiency by periodically defrosting or adjusting the fan speed. The defrosting process is usually automatically controlled according to the evaporation temperature or cycle setting, and the frost layer on the evaporator surface is melted by reverse operation or stopping the compressor.

7. The method for operating a screw air-cooled chiller according to claim 1, characterized in that: The S5 further includes continuously monitoring the operating status of the equipment by arranging multiple sensors in the system and combining the real-time monitoring function of the electronic control system. When the system detects an abnormality, the electronic control system will automatically execute corresponding protection measures according to the type and severity of the fault. When the fault level is high, the electronic control system will execute an automatic shutdown procedure, quickly cut off the power supply and start the backup system. The system will transmit the fault information to the monitoring platform or the operator's mobile device in real time through the networking function, and issue an alarm notification. The fault level is evaluated based on the comparison of the real-time data of the equipment with the preset threshold, and the trend is analyzed with the help of intelligent algorithms to predict potential fault risks.

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