Analysis Of 10 Common Malfunction In Refrigeration Maintenance (II)

- Jul 30, 2019-

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4.  Liquid Hit:


1). Avoid inhalation temperatures that are too high or too low. If the suction temperature is too low, it means that the refrigerant is not completely evaporated in the evaporator, which reduces the heat exchange efficiency of the evaporator, and the suction of the wet steam will form a compressor liquid hammer. The inspiratory temperature should be 5 to 10 ° C higher than the evaporation temperature under normal conditions.


2). In order to ensure the safe operation of the compressor and prevent the occurrence of liquid hammer, the inhalation temperature is required to be higher than the evaporation temperature, that is, it should have a certain degree of superheat


5. Refrigeration System with liquid start:


1). Foaming with liquid start can be clearly observed on the oil sight glass. The root cause is that a large amount of refrigerant dissolved in the lubricating oil and sinking under the lubricating oil suddenly boils when the pressure suddenly drops, and causes the foaming phenomenon of the lubricating oil, which easily causes liquid shock.


2). The compressor is equipped with a crankcase heater (heater) to prevent refrigerant migration. Shut down for a short time to maintain the crankcase heater energized. After a long period of downtime, heat the oil for several or ten hours before starting the machine. The installation of a gas-liquid separator on the return line can increase the resistance of refrigerant migration and reduce the amount of migration.


6. Refrigeration system appears oil return:


1). Lack of oil can cause serious lubrication shortage. The root cause of lack of oil is not how much and how slow the compressor is, but the system is not good. The oil separator can be installed to quickly return oil and extend the compressor's return-free operation time.


2). When the compressor is higher than the evaporator, there is no oil return bend on the vertical return pipe. The oil return bend should be as compact as possible to reduce oil deposits. The spacing between the oil return bends should be appropriate. When the number of oil return bends is relatively large, some lubricants should be added.


3). The compressor starts frequently. The frequent start of the compressor is not conducive to oil return. Since the continuous operation time is short, the compressor stops, and the return air pipe does not have a stable high-speed air flow, and the lubricating oil can only remain in the pipeline. If the oil is less than the oil, the compressor will be short of oil. The shorter the running time, the longer the pipeline, the more complicated the system, the more prominent the oil return problem