What blockages may occur in the refrigeration system? How to solve it?

1. Oil blockage

The main reason for oil blockage is that the compressor cylinder is severely worn or the cylinder 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.

Treatment method for oil blockage:

When the filter is blocked by oil, a new filter should be replaced, and some of the refrigeration oil accumulated in the condenser should be blown out with high-pressure nitrogen. It is best to heat the condenser with a hair dryer when nitrogen is introduced.

Hazards of oil film:

• If an oil film adheres to the surface of the heat exchanger, the condensation temperature will rise and the evaporation temperature will drop, resulting in increased energy consumption;
• When a 0.1mm oil film adheres to the surface of the condenser, 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:

• Using high-efficiency oil separation 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 gas.

2. Ice blockage failure

Ice blockage failure mainly occurs because the refrigeration system contains excessive water. As the refrigerant circulates continuously, the water in the refrigeration system gradually concentrates at the throttle valve outlet. Since the temperature at the throttle valve outlet is the lowest, the water freezes into ice and gradually increases. When it reaches a certain level, it completely blocks the capillary tube and the refrigerant cannot circulate.

Main sources of water:

• Residual water in the refrigeration system components and connecting pipes due to insufficient drying;

• Refrigeration oil and refrigerant contain more water than allowed;

• Moisture is caused by failure to vacuumize or improper installation during installation;

• The motor insulation paper in the compressor contains water.

Symptoms of ice blockage:

• The airflow gradually weakens and becomes intermittent;

• When the blockage is serious, the sound of the airflow disappears, the refrigerant circulation 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 starts to be produced again (the cold ice begins to melt)

• Ice blockage forms a cycle of sometimes unblocked and sometimes blocked, blocked and unblocked, and unblocked and blocked again.

Treatment of ice blockage:

Ice blockage in the refrigeration system is caused by excessive water in the system, so the entire refrigeration system must be dried. The treatment methods are as follows:

• Vacuum, replace the drying filter, and wait until the water 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 stages, replace the filter, replace the refrigeration oil, replace the refrigerant, and vacuum until the water indicator in the sight glass turns green.

3. Dirty blockage failure

When the refrigeration system is dirty and blocked, the refrigerant cannot circulate, causing the compressor to run continuously, the evaporator is not cold, the condenser is not hot, the compressor shell is not hot, and there is no sound of airflow 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 causes of dirty blockage:

• Dust and metal chips during construction and installation, and the oxide layer on the inner wall of the pipe falls off during pipe welding;

• During the processing of each component, the inner and outer surfaces are not cleaned, and the pipeline is not tightly sealed, allowing dust to enter the pipe;

• Impurities in the refrigeration oil and refrigerant, and 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 can also easily cause dirty blockage.

Performance after dirty blockage:

• If it is partially blocked, the evaporator feels cool or icy, but there is no frost;

• When touching the outer surface of the filter drier and the throttle valve, it feels very cold, there is frost, 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.