• Common faults of cold storage equipment
    Common faults of cold storage equipment May 23, 2022
    1. Refrigerant leakage: After the refrigerant leaks in the system, the cooling capacity is insufficient, the suction and exhaust pressures are low, and the intermittent airflow sound much larger than usual can be heard at the expansion valve. There is no frost or a small amount of floating frost on the evaporator. If the expansion valve hole is enlarged, the suction pressure still does not change greatly. After the shutdown, the equilibrium pressure in the system is generally lower than the saturation pressure corresponding to the same ambient temperature. 2. Excessive charging of refrigerant after maintenance: The amount of refrigerant charged in the refrigeration system after maintenance exceeds the capacity of the system, and the refrigerant will occupy a certain volume of the condenser, reduce the heat dissipation area, and reduce the cooling effect. The suction and exhaust pressure are generally higher than the normal pressure value, the cooler unit is not frosted solidly, and the cooling in the warehouse is slow 3. There is air in the refrigeration system: the air in the refrigeration system will reduce the refrigeration efficiency. The obvious phenomenon is that the suction and exhaust pressures increase (but the exhaust pressure has not exceeded the rated value), and the compressor of condensing unit outlet to the condenser inlet The temperature increases significantly. Due to the presence of air in the system, the exhaust pressure and exhaust temperature increase. 4. Low compressor efficiency: The low efficiency of the refrigeration compressor of condensing unit refers to the fact that the actual exhaust volume decreases and the refrigeration capacity decreases accordingly when the working conditions remain unchanged. This phenomenon mostly occurs in compressors that have been used for a long time. The wear and tear of the compressors are large, the matching clearance of each component is large, and the sealing performance of the air valve is reduced, resulting in a decrease in the actual exhaust volume. 5. The frost on the surface of the evaporator is too thick: the long-term use of the cold storage evaporator should be defrosted regularly. If it is not defrosted, the frost layer on the evaporator pipeline will accumulate and thicken. When the entire pipeline is wrapped into a transparent ice layer, It will seriously affect the heat transfer, causing the temperature in the warehouse to fall below the required range. 6. There is refrigerated oil in the evaporator pipeline: During the refrigeration cycle, some refrigerated oil remains in the evaporator pipeline. After a long period of use, if there is a lot of residual oil in the evaporator, it will seriously affect its heat transfer effect. , the phenomenon of poor cooling occurs. 7. The refrigeration system is not smooth: due to the poor cleaning of the refrigeration system, after a period of use, the dirt gradually accumulates in the filter, and some meshes are blocked, which reduces t...
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  • Description of common components of cold storage system
    Description of common components of cold storage system May 23, 2022
    1. Compressor: It plays the role of compressing and driving the refrigerant in the refrigerant circuit, and is the power of the refrigeration system. 2. Condenser: It is one of the main heat exchange equipment in the refrigeration system of cold storage. Its function is to cool and condense the superheated vapor of the high-temperature refrigerant discharged from the compressor of the assembled cold storage into high-pressure liquid. 3. Evaporator: The liquid refrigerant evaporates at low pressure and low temperature, absorbs the heat from the freezer and evaporates, and turns into a gaseous refrigerant. The gaseous refrigerant is sucked into the compressor and compressed, and then discharged into the condenser to discharge heat. Basically, the principle of the evaporator and the condenser is the same, the difference is that the former absorbs heat into the storehouse, and the latter exhausts heat to the outside. 4. Liquid storage tank: store Freon storage tank to ensure that the refrigerant is always in a saturated state. 5. Solenoid valve: The first is to prevent the high-pressure part of the refrigerant liquid from entering the evaporator when the compressor is stopped, to prevent the low-pressure from being too high when the compressor is started next time, and to prevent the compressor from liquid shock. Second, when the temperature of the cold storage reaches the set value, the thermostat will act, the solenoid valve will lose power, and the compressor will stop when the low pressure pressure reaches the set value. When the electricity is turned on, the compressor starts when the low pressure pressure rises to the compressor start setting value. 6. High and low pressure protector: to prevent high pressure and low pressure from being too low to protect the compressor. 7. Thermostat: It is equivalent to the brain of the cold storage that controls the opening and stopping of refrigeration, defrosting, and the opening and stopping of fans. 8. Dry filter: filter impurities and moisture in the system. 9. Oil pressure protector: ensure that the compressor has enough lubricating oil. 10. Expansion valve: The high-pressure refrigeration liquid at the outlet of the expansion valve is rapidly expanded and evaporated, and the heat in the air is absorbed through the tube wall for cold and heat exchange. 11. Oil separator: its function is to separate the lubricating oil in the high-pressure steam discharged from the refrigeration compressor to ensure the safe and efficient operation of the device. According to the principle of oil separation by reducing the airflow speed and changing the airflow direction, the oil particles in the high-pressure steam are separated under the action of gravity. Generally, when the airflow velocity is below 1m/s, the oil particles with a diameter of more than 0.2mm contained in the steam can be separated. There are four types of oil separators commonly used: washing type, centrifugal type, packing type and filter type. 12. ...
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  • the classification of cold storage temperature
    the classification of cold storage temperature May 19, 2022
    Cold storage is usually divided into four temperatures: high temperature, medium and low temperature, low temperature, and ultra-low temperature. Different ingredients require different temperatures. A. High temperature cold storage The high temperature cold storage is what we call the cold storage cold storage. Adhere to the temperature is usually around 0 ° C, and air cooler unit with a cooling fan. B. Medium and low temperature cold storage The medium and low temperature cold storage is the high temperature freezing cold storage, the temperature is usually within -18°C, and it is mainly used to store meat, water commodities and commodities suitable for this temperature range. C, low temperature cold storage Low-temperature cold storage, also known as freezing storage, freezing cold storage, usually the storage temperature is about -20°C~-30°C, and the freezing of food is completed by air cooler or special freezing equipment. D. Ultra-low temperature cold storage Ultra-low temperature cold storage, ≤-30 °C cold storage, is mainly used for quick-frozen food and special purposes such as industrial experiments and medical treatment. Compared with the above three, the applications on the market need to be slightly smaller.
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  • The difference between water cooled chiller and air cooled chiller
    The difference between water cooled chiller and air cooled chiller May 17, 2022
    Industrial chillers are divided into water cooled industrial chillers and air cooled industrial chillers. The difference between them is mainly the difference in condensers. The condenser of the water cooled chiller mainly removes heat by circulating cooling water, so the water cooled condenser of the water cooled chiller is also commonly called a water cannon. Different from the water cooled type, the air cooled industrial chiller uses a fan for heat dissipation. A finned condenser is usually used. The fins actually refer to aluminum sheets. The parts that need heat exchange are externally installed with aluminum sheets to achieve efficient heat dissipation, and then the hot air is drawn out through a powerful fan. Therefore, when the temperature of the workshop is high, the air-cooled chiller will not only be affected by itself (the high temperature of the condenser will directly cause the high pressure alarm of the industrial chiller, and the cooling capacity will decrease), it will also have a direct impact on the temperature of the workshop. The advantages of water-cooled chillers are obvious. The water-cooled industrial chiller requires the cooling water tower to circulate cooling water to cool down. Therefore, to use the water-cooled chiller, it is necessary to install the cooling water tower, the cooling water circulating pump, and the pipeline, which is cumbersome. Compared with air-cooled industrial chillers, the ease of movement pales in comparison. But in most cases factories are already equipped with cooling water circulation system.
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  • The basic composition of the chiller refrigeration system
    The basic composition of the chiller refrigeration system May 17, 2022
    Condenser: In 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, all the heat absorbed in the working process, including the heat absorbed from the evaporator and the refrigeration compressor and in the pipeline, is transferred to the surrounding medium (water or Air) is taken away; the high-pressure superheated vapor of the refrigerant is re-condensed into a liquid. (According to the different cooling medium and cooling methods, condensers can be divided into three categories: water cooled condensers, air cooled condensers, and evaporative condensers.) Liquid accumulator: The liquid accumulator is installed after the condenser and is directly connected to the discharge 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. For the small chiller refrigeration system, the liquid receiver is often not installed, but the condenser is used to adjust and store the refrigerant. Filter drier: In the refrigeration cycle of the chiller, it is necessary to prevent the entry of moisture and dirt (oil, iron filings, copper filings), etc. The source of moisture is mainly the trace moisture contained in the newly added refrigerant and lubricating oil, or due to Moisture from air ingress during system maintenance. If the water in the system is not removed, when the refrigerant passes through the throttle valve (thermal expansion valve or capillary), the water will sometimes freeze into ice due to the drop in pressure and temperature, blocking the channel and affecting the normal operation of the refrigeration device. Therefore, a filter drier must be installed in the chiller refrigeration system. Evaporator: The evaporator is a heat exchange device that relies on the evaporation (actually boiling) of the refrigerant liquid to absorb the heat of the cooled medium. Its function in the refrigeration system is to absorb heat (or output cooling). 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. Thermal expansion valve: The thermal expansion valve is not only a flow control valve in the chiller refrigeration system, but also a throttle valve in the refrigeration equipment. It is installed between the drying filter and the evaporator in the refrigeration equipment. It is wrapped at the outlet of the evaporator. Its main function is to throttle and depressurize the high-pressure and normal-temperature r...
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  • Introduction of air-cooled chiller
    Introduction of air-cooled chiller May 17, 2022
    Air-cooled chiller: a type of chiller, the water at room temperature is cooled to a certain temperature by the compressor of the condensing unit to strengthen the cooling of the mold or machine, as a stand-alone use, the heat dissipation device is a built-in fan, there are mainly three mutual Contact systems: refrigerant circulation system, water circulation system, electrical automatic control system. Refrigerant circulation system: The liquid refrigerant in the evaporator absorbs the heat in the water and begins to evaporate, and finally a certain temperature difference is formed between the refrigerant and the water, and the liquid refrigerant is also completely evaporated into a gaseous state, which is then sucked in and compressed by the compressor. (increase in pressure and temperature), the gaseous refrigerant absorbs heat through the condenser and condenses into a liquid. After throttling through the expansion valve (or capillary), it becomes a low temperature and low pressure refrigerant and enters the evaporator to complete the refrigerant cycle process. Water circulation system: The water pump is responsible for pumping 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. Electrical automatic control system: including power supply part and 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-stop, protection and other functions according to the water temperature.
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  • Operating principle of air-cooled screw heat pump unit
    Operating principle of air-cooled screw heat pump unit May 12, 2022
    The air-cooled screw cold water heat pump unit is a central air-conditioning unit that uses air as the cooling medium (summer) and heat source (winter), water as the refrigerant, and adopts a vapor compression refrigeration cycle. The unit has the characteristics of both heating and cooling. It can form a centralized or semi-centralized central air-conditioning system together with fan coil units, air conditioning boxes, and air handlers. It has the characteristics of flexible layout and various control methods. Refrigeration cycle: During refrigeration: the compressor continuously extracts the refrigerant vapor from the evaporator, and after compression by the compressor, the refrigerant changes from low temperature and low pressure vapor to high temperature and high pressure vapor. The high-temperature and high-pressure refrigerant vapor is condensed in the air cooled condenser, and a large amount of heat is released and absorbed by the air. The high-pressure liquid refrigerant condensed by the air cooled condenser is throttled and depressurized by the thermal expansion valve, and turned into a low-pressure refrigerant liquid. The low-pressure refrigerant evaporates in the evaporator and absorbs a lot of heat from the refrigerant water, thereby reducing the temperature of the refrigerant water and achieving the purpose of refrigeration. The low pressure refrigerant vapor is extracted by the compressor, thus forming a refrigeration cycle. Heating cycle: When heating: the compressor of condensing unit continuously extracts the refrigerant vapor from the evaporator, and after being compressed by the compressor, the refrigerant changes from low temperature and low pressure vapor to high temperature and high pressure vapor. The high temperature and high pressure refrigerant vapor is condensed in the condenser, and a large amount of heat is released and absorbed by the heat medium water, so as to achieve the purpose of heating. The low pressure refrigerant vapor is extracted by the compressor, thus forming a heating cycle.
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  • Characteristics and Treatment Methods of Oil Plugging in Refrigeration System of Cold Storage
    Characteristics and Treatment Methods of Oil Plugging in Refrigeration System of Cold Storage May 10, 2022
    The oil blockage of the refrigeration system of the cold storage refers to the phenomenon that the valve hole of the thermal expansion valve is blocked by the solidified lubricating oil and hinders the flow of the refrigerant. It usually occurs in the refrigeration system of low-temperature cold storage, or due to the selection of high freezing point and inferior refrigeration oil. Because the freezing point of inferior refrigeration oil is high, it may cause the refrigeration lubricating oil to flow through the valve hole of the thermal expansion valve after mixing with the refrigerant. , Due to the sudden drop in temperature, part of the lubricating oil is precipitated from the refrigerant and frozen into a thick paste, causing the valve hole of the thermal expansion valve to be blocked. When encountering the problem of oil blockage in the refrigeration system, it is usually necessary to replace the refrigeration oil.
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