Maintenance Method of Chiller Unit
Refrigeration chillers are composed of three interrelated systems: refrigerant circulation system, water circulation system, and electrical automatic control system.
1. Refrigerant circulation system:
The liquid refrigerant in the evaporator absorbs the heat in the water and starts to evaporate. The liquid refrigerant is also completely evaporated into a gaseous state and then sucked in and compressed by the compressor. The gaseous refrigerant absorbs heat through the condenser, condenses into liquid, and passes through the thermal expansion valve ( After throttling, it becomes a low temperature and low pressure refrigerant and enters the evaporator to complete the refrigerant cycle.
2. the basic composition of the refrigeration system:
Compressor: The compressor is the core component of the refrigeration system, and its function is to convert the input electrical energy into mechanical energy and compress the refrigerant.
Condenser: During the refrigeration process, the condenser plays the role of outputting heat energy and condensing the 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 and in the pipeline is transferred to the surrounding medium (water or air) to take away; the refrigerant high-pressure superheated vapor Recondenses into liquid.
Liquid accumulator: The liquid accumulator is installed after the condenser and is directly connected to the drain pipe of the condenser. The refrigerant liquid of the condenser should flow into the liquid receiver unimpeded, 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 demand of the refrigerant liquid also changes accordingly, and the accumulator plays the role of adjusting and storing the refrigerant at that time.
Filter drier: In the refrigeration cycle, it is necessary to prevent the entry of moisture and dirt (oil, iron filings, copper filings), etc. If the moisture in the system is not completely removed, when the refrigerant passes through the throttle valve (thermal expansion valve or capillary) When , Due to the drop of pressure and temperature, sometimes the water will freeze into ice, which will block the channel and affect the normal operation of the refrigeration device.
Thermal expansion valve: The thermal expansion valve is both a flow control valve and a throttle valve in the refrigeration system. It is installed between the drying filter and the evaporator in the refrigeration equipment, and its temperature sensing package is wrapped at the outlet of the evaporator. place. Its main function is to throttle and depressurize the high-pressure and normal-temperature refrigerant liquid when it flows through the thermal expansion valve, and turn it into a low-temperature and low-pressure refrigerant wet vapor (enter the evaporator, vaporize and absorb heat in the evaporator, and achieve the purpose of cooling and cooling.
Evaporator: The evaporator is a heat exchange device that relies on the evaporation of the refrigerant liquid to absorb the heat of the cooled medium. Its function in the refrigeration system is to absorb heat (or output cold). In order to ensure that the evaporation process can be carried out stably and lastingly, the evaporating gas must be continuously pumped out by the refrigeration compressor to maintain a certain evaporation pressure.
Refrigerant: NTC uses R22 as refrigerant. Its role is to carry heat and to achieve heat absorption and heat release when the state changes.
3. Water circulation system:
The water circulation system is a water pump that pumps water from the water tank to the equipment that the user needs to cool. The chilled water takes away the heat and then the temperature rises, and then returns to the chilled water tank.
4. Electrical automatic control system:
The electrical automatic control system includes the power supply part and the automatic control part.
The power supply part supplies power to compressors, fans, water pumps, etc. through contactors.
The automatic control part includes thermostat, pressure protection, delay device, relay, overload protection, etc. to achieve automatic start and stop according to the water temperature, protection and other functions.
3. Maintenance of the chiller:
The compressor of the refrigeration unit is a very critical component in the unit. The quality of the compressor is directly related to the stability of the unit. Therefore, regular maintenance is required. Common maintenance includes:
1. Replace the lubricating oil
After the refrigeration unit is used for a long time, the oil quality of the lubricating oil deteriorates, and the impurities and moisture inside the oil increase, so the oil quality should be observed and checked regularly. Once a problem is found, it should be replaced in time, and the replaced lubricating oil grade must conform to the technical data.
2. Replace the filter drier
The filter drier is an important part to ensure the normal circulation of the refrigerant. Since water and refrigerant are immiscible with each other, if the system contains moisture, it will greatly affect the operating efficiency of the unit. Therefore, it is very important to keep the inside of the system dry, and the filter element inside the drying filter must be replaced regularly.
3. Calibration of safety valve
The condenser and evaporator on the chiller are pressure vessels. According to the regulations, a safety valve should be installed on the high-pressure side of the chiller, that is, the condenser body. Once the chiller is in an abnormal working environment, the safety valve can automatically release pressure. In order to prevent the high pressure may cause damage to the human body. Therefore, the regular calibration of the safety valve is very important for the safety of the entire unit.
4. Cleaning of condenser and evaporator
Because the cooling water of the water-cooled condenser is an open circulation loop, the tap water generally used is recycled through the cooling tower. When the content of calcium salt and magnesium salt in the water is large, it is easy to decompose and deposit on the cooling water pipe to form scale, which affects the heat transfer. If the scale is too thick, the cooling water circulation section will be reduced, the water volume will be reduced, and the condensing pressure will increase. Therefore, when the quality of the cooling water used is poor, the cooling water pipes should be cleaned at least once a year to remove scale and other dirt in the pipes. There are usually two ways to clean the condenser water pipes:
(1) Use a special cleaning gun to clean the pipe.
(2) Use a special cleaning agent to circulate and rinse, or fill it in cooling water, and then change the solution after 24 hours until it is cleaned.
