1. The working principle of water chiller: Industrial water chiller consists of three interrelated systems: refrigerant cycle system, water cycle system and electrical automatic control system.            Refrigerant cycle system: the liquid refrigerant in the evaporator absorbs heat from water and begins to evaporate. The liquid refrigerant is also completely evaporated into gaseous state and then inhaled and compressed by the compressor. The gaseous refrigerant absorbs heat through the condenser and condenses into liquid. After throttling by the thermal expansion valve (or capillary), it becomes a low-temperature and low-pressure refrigerant and enters the evaporator to complete the refrigerant cycle process. 。            2. The basic composition of the refrigeration system:            Compressor: Compressor is the core component of refrigeration system. Its function is to convert the input electric energy into mechanical energy and compress refrigerant.            Condenser: In the process of refrigeration, the condenser plays the role of exporting heat energy and condensing refrigerant. After the high-pressure superheated vapor discharged from the refrigeration compressor enters the condenser, the heat absorbed from the evaporator and the refrigeration compressor as well as in the pipeline is transferred to the surrounding medium (water or air); the high-pressure superheated vapor of the refrigerant re-condenses into liquid.            Storage: After the storage device is installed in the condenser, it is directly connected with the discharge pipe of the condenser. The refrigerant liquid of the condenser should flow unimpeded into the reservoir, so that the cooling area of the condenser can be fully utilized. On the other hand, when the heat load of the evaporator changes, the refrigerant liquid requirement also changes. At that time, the reservoir will play the role of adjusting and storing refrigerants.            Drying filter: In the refrigeration cycle, water and dirt (oil, iron, copper) must be prevented from entering. If the water in the system is not removed, when the refrigerant passes through the throttle valve (thermal expansion valve or capillary), water sometimes solidifies into ice due to the drop of pressure and temperature, which blocks the passage and affects the normal operation of the refrigeration device.            Thermal Expansion Valve: Thermal Expansion Valve is not only a flow regulating valve, but also a throttle valve in the refrigeration system. It is installed between the drying filter and the evaporator in the refrigeration equipment. Its temperature-sensitive wrap is wrapped at the outlet of the evaporator. Its main function is to make the refrigerant liquid at high pressure and normal temperature throttle and depressurize when flowing through the thermodynamic expansion valve, and turn into the low temperature and low pressure refrigerant wet vapor (entering the evaporator, vaporizing and absorbing heat in the evaporator), so as to achieve the purpose of cooling.            Evaporator: Evaporator is a heat exchanger that absorbs heat from the cooling medium by evaporation of refrigerant liquid. Its function in refrigeration system is to absorb heat (or output cooling). In order to ensure the steady and lasting evaporation process, it is necessary to continuously use refrigeration compressor to extract the evaporated gas to maintain a certain evaporation pressure.            Refrigerant: R22 as refrigerant. Its function is to carry heat, and to achieve endothermic and exothermic changes in the state.            3. Water circulating system: Water circulating system is a device that pumps water out of the water tank to be cooled by the user. After the heat is taken away by the chilled water, the temperature rises and then returns to the chilled water tank.            4. Electrical automatic control system:            Electrical automatic control system includes power supply part and automatic control part.            The power supply part supplies power to compressors, fans and pumps through contactors.            The automatic control part includes temperature controller, pressure protection, delay device, relay and overload protection, which can automatically start and stop and protect according to water temperature.            5. Work before operation of industrial water chiller: Install the machine in a strong place. In order to facilitate operation and maintenance, the machine must be surrounded by more than one meter of space, without heat source, harmful gas, steam and flammable gas, so as to ensure safe operation and safety from machine pollution.            The machine should be placed in a place close to the power source and the supply water source and convenient wiring. There should be drainage pipes around the machine. If the machine is placed in the open air, rain protection and sunscreen shelters should be erected.            The place where the machine is installed should be ventilated and equipped with ventilation equipment to ensure that the temperature around the machine does not exceed 35 C. In cold areas, it is necessary to ensure that the temperature around the machine does not exceed zero degree in order to avoid freezing the machine.            The dimension and specification of the pipeline connected with the machine should refer to the specification of the technical parameter table and can not be changed arbitrarily.            Power Connection: Connect the auxiliary power cord (5m) which has been connected to the switch of the control unit to the power supply. At this time, the grounding terminal (E) must be connected. Otherwise, there will be electric shock because of misoperation and leakage of water and oil.            Machine water supply: Close water tank drainage valve, open water source valve, water supply valve, cold water output valve, cold water input valve.            For the water temperature and flow rate of cooling water and refrigerant water, users should base on the data provided in the technical parameter table, otherwise the machine will not work properly.            Inspection before machine operation:            Check whether the inlet and outlet valves of the die are opened.            Check whether the amount of water in the cold water tank is sufficient, whether the water supply and replenishment are normal.            Check whether the whole piping system is adequately watered and the air is exhausted.            Check whether the supply voltage is normal.            Check whether the ground wire is firmly connected. 

Screw chiller has compact structure, high working efficiency, energy saving, electricity saving and easy operation. It is an industrial refrigeration equipment often used by many large enterprises. But after a long time of use, it will certainly cause a certain degree of wear and tear, so how to effectively extend its service life?            Firstly, the cleaning and maintenance rules and regulations of screw chillers should be formulated to record each maintenance work. The cleaning of the unit is not only for appearance, but also for evaporator, condenser, pipeline, filter, cooling tower, fan and other parts of the unit, so as to avoid impurity scaling in water quality affecting the normal operation of the chiller.            Secondly, according to the use time of screw chiller, the compressor lubricant is replaced. The main function of lubricating oil for compressor is lubrication, cooling and capacity adjustment. It is suggested that the lubricating oil should be checked once every 10000 hours when the water cooler is running, and the lubricating oil should be replaced every 20000 hours or every 4 years. When changing lubricants, you should choose the oil that has passed the quality certification. Different brands of oil can not be mixed!            Thirdly, when using screw chiller, operators should always pay attention to shut down the chiller in time to prevent the unit from being damaged again once the chiller has abnormal sound or failure. Then according to the fault prompt in the water chiller control panel, troubleshooting is carried out. When the fault has not been eliminated, remember not to start the water chiller. If you encounter trouble that can not be eliminated by yourself, please contact professional maintenance personnel to deal with it in time.            Finally, the data of unit operation (including unit maintenance) are recorded regularly to facilitate future inquiries. After a long period of use, the components of the unit should be inspected to ensure that they can work properly. If the machine does not need to run for a long time, the water inside the unit and the pipeline should be cleaned up to avoid damage to the unit components.            Generally speaking, screw chillers need to run for a long time. In order to prolong the service life of the chillers, users are advised to formulate rules for safe operation and maintenance of the chillers, so as to effectively ensure the long-term use of the chillers.