How to solve the blockage failure in the refrigeration system is a concern for many users. The blockage of the refrigeration system is mainly caused by oil blockage, ice blockage or dirt blockage of the throttle valve, or dirt blockage of the dry filter. Today, the Refrigeration Encyclopedia WeChat public account will give you a detailed introduction to the causes and solutions of the system blockage. I hope this article can bring you some help.
1. Oil blockage failure
The main reason for oil blockage is that the compressor cylinder is severely worn or the cylinder fit clearance is too large. The gasoline discharged from the compressor is discharged into the condenser, and then enters the dry filter together with the refrigerant. Due to the high viscosity of the oil, it is blocked by the desiccant in the filter. When there is too much oil, it forms a blockage at the filter inlet, so that the refrigerant cannot circulate normally.
There is too much refrigeration oil remaining in the refrigeration system, which affects the refrigeration effect or even fails to refrigerate. Therefore, the refrigeration oil in the system must be cleaned.
How to deal with oil blockage:
When the filter is blocked by oil, a new filter should be replaced, and at the same time, high-pressure nitrogen should be used to blow out part of the refrigeration oil accumulated in the condenser. It is best to use a hair dryer to heat the condenser when nitrogen is introduced.
Harm of oil film:
If the oil film is attached to the surface of the heat exchanger, the condensation temperature will rise and the evaporation temperature will drop, resulting in increased energy consumption;
When the condenser surface is attached with a 0.1mm oil film, the refrigeration capacity of the refrigeration compressor will drop by 16% and the power consumption will increase by 12.4%;
When the oil film in the evaporator reaches 0.1mm, the evaporation temperature will drop by 2.5℃ and the power consumption will increase by 11%.
Oil film treatment method:
The use of high-efficiency oil separators can greatly reduce the amount of oil entering the system pipeline;
If the system already has an oil film, it can be flushed with nitrogen several times until there is no mist.
2. Ice blockage failure
Ice blockage failure occurs mainly because the refrigeration system contains excessive water. With the continuous circulation of the refrigerant, the water in the refrigeration system gradually concentrates at the outlet of the throttle valve. Since the temperature at the outlet of the throttle valve is the lowest, the water freezes and gradually increases. To a certain extent, the capillary is completely blocked and the refrigerant cannot circulate.
The main sources of moisture:
The moisture left in the components and connecting pipes of the refrigeration system due to insufficient drying;
The refrigeration oil and refrigerant contain more moisture than allowed;
The installation is not vacuumed or improperly installed, resulting in moisture;
The motor insulation paper in the compressor contains moisture.
The manifestation of ice blockage:
The airflow gradually weakens and intermittently;
When the blockage is serious, the sound of the airflow disappears, the refrigerant cycle is interrupted, and the condenser gradually becomes cooler;
Due to the blockage, the exhaust pressure increases, and the sound of the machine operation increases;
No refrigerant flows into the evaporator, the frosting area gradually decreases, and the refrigeration effect becomes worse;
After a period of shutdown, the refrigerant begins to be re-made (the cold ice begins to melt)
The ice blockage forms a periodic repetition of being unblocked for a while, blocked again, unblocked again, and unblocked again.
Ice blockage treatment:
The ice blockage failure of the refrigeration system is due to excessive moisture in the system, so the entire refrigeration system must be dried. The treatment methods are as follows:
Evacuate, replace the dry filter, and wait until the moisture indicator in the sight glass of the refrigeration system turns green to be qualified;
If a large amount of water enters the system, use nitrogen to flush the dirt in sections, replace the filter, replace the refrigeration oil, replace the refrigerant, and vacuum until the moisture indicator in the sight glass turns green.
3. Dirty blockage failure
After the refrigeration system is dirty and blocked, the refrigerant cannot circulate, so the compressor runs continuously, the evaporator is not cold, the condenser is not hot, the compressor shell is not hot, and there is no airflow sound in the evaporator. If there are many impurities in the system, the dry filter will gradually be blocked, and the filter screen of the throttling mechanism will be blocked.
The main reasons for dirty blockage:
Dust and metal chips during construction and installation, and the oxide layer on the inner wall of the pipeline falls off during welding;
During the processing of each component, the inner and outer surfaces are not cleaned, and the pipeline is not tightly sealed, and dust enters the pipe;
Refrigeration oil and refrigerant contain impurities, and the poor quality desiccant powder in the dry filter;
The distance between the capillary and the filter screen in the dry filter is too close, which is also easy to cause dirty blockage.
Performance after dirty blockage:
If it is partially blocked, the evaporator feels cool or icy, but not frosted;
When touching the outer surface of the filter drier and the throttle valve, it feels very cold, frosted, and even a layer of white frost;
The evaporator is not cold, the condenser is not hot, and the compressor shell is not hot.
Treatment of dirty blockage: Dirty blockage is generally in the filter drier, throttling mechanism filter, suction filter, etc. The throttling mechanism filter and the suction filter can be removed and cleaned, and the filter drier is generally replaced. After the replacement is completed, the refrigeration system needs to be leak-checked and vacuumed.
