Do you really know the differences and ways to resolve ice blockage, dirt blockage, and oil blockage in refrigeration systems?
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Causes and symptoms of ice blockage: Ice blockage occurs mainly due to an excessive amount of moisture in the refrigeration system. As the refrigerant circulates continuously, this moisture gradually accumulates at the outlet of the expansion valve. Since the temperature at the outlet of the expansion valve is the lowest, the water freezes into ice, which continues to grow in size. Once it reaches a certain size, it completely blocks the expansion valve, preventing the refrigerant from circulating and thus preventing the freezer from cooling. The signs of ice blockage in a refrigeration system are that it operates normally at first; frost forms inside the evaporator, the condenser dissipates heat effectively, the unit runs smoothly, and the sound produced by the refrigerant moving inside the evaporator is clear and steady. As ice blockage forms, the airflow can be heard to weaken gradually and become intermittent; when the blockage is severe, the sound of airflow disappears, the refrigerant circulation is interrupted, and the condenser gradually cools down. Due to the blockage, the exhaust pressure increases, the noise generated by the machine rises, no refrigerant flows into the evaporator, the frost formation area gradually decreases, the temperature rises as well, and the temperature of the expansion valve also increases. As a result, the ice begins to melt, and at this point the refrigerant starts circulating again. After some time, ice blockage occurs again, resulting in a periodic pattern of flow and blockage. Troubleshooting ice blockage faults: Ice blockage faults in a refrigeration system occur due to an excessive amount of moisture within the system; therefore, it is necessary to dry out the entire refrigeration system. There are two methods for handling this: 1. Use a drying oven to heat and dry each component; the compressor, condenser, evaporator, expansion valve, and return pipe in the refrigerant system are removed from the cold storage and placed in the drying oven for heating and drying. 2. Use heating vacuuming and secondary vacuuming to remove moisture from various components of the refrigeration system.
Causes and symptoms of fouling Fouling occurs due to an excessive amount of impurities in the refrigeration system. The main sources of impurities in the system include dust and metal shavings from the manufacturing process of refrigeration equipment, the oxidation layer on the inner walls of pipes that comes off during welding, inadequate cleaning of the inner and outer surfaces of various components during processing, dust entering the pipes due to poor sealing, as well as impurities present in the refrigeration oil and refrigerant, along with low-quality desiccant powder in the dry filters ； Additionally, when welding the expansion valve and the dryer filter, it is also easy to block the valve port with welds. Difference between ice blockage and dirt blockage: After ice blockage occurs, cooling can still be restored; there is a periodic pattern of periods of functionality followed by blockages, with the condition alternating between blocked and unblocked states. And once it gets clogged, it can no longer cool. Methods for troubleshooting clogged expansion valves: Use high-pressure nitrogen in combination with other methods to blow out the debris blocking the expansion valve. Once the expansion valve is cleared, clean and dry all components within the refrigeration system, then reassemble and weld them together to resolve the issue. If the expansion valve is severely clogged and the above methods fail to resolve the issue, the problem can be fixed by replacing the expansion valve.
Oil blockage faults and other types of pipeline blockages: The main reasons for oil blockage in a refrigeration system are severe wear of the compressor cylinder or an excessive clearance between the piston and the cylinder. The gasoline discharged from the compressor is sent to the condenser, and from there it enters the dryer-filter along with the refrigerant. Due to the high viscosity of the oil, it is blocked by the desiccant inside the filter; when there is too much oil, a blockage forms at the inlet of the filter, preventing the refrigerant from circulating properly and resulting in the cooling equipment failing to cool. Other causes of blockages in the pipelines are: blockage by solder during pipeline welding; or the replacement pipe itself being blocked but going unnoticed when replacing it. All such blockages are caused by human error, so it is necessary to follow the proper procedures and conduct thorough inspections during welding and pipe replacement to avoid such blockage problems. Troubleshooting oil blockage: The occurrence of oil blockage indicates that there is an excessive amount of refrigerant oil remaining in the cooling system, which affects the cooling efficiency or even prevents cooling altogether; therefore, it is necessary to remove all the refrigerant oil from the system. When the filter becomes clogged with oil, a new filter should be installed. At the same time, high-pressure nitrogen should be used to blow out any frozen oil that has accumulated in the condenser; an electric hair dryer can be used to heat the condenser while nitrogen is being introduced.
The refrigerant side and the oil side of the refrigeration system also need to be cleaned, but in reality it is not possible to carry out such cleaning. Instead, we use refrigerant additives to clean the oil side and the refrigerant side, removing the oil film on the surface of the evaporator as well as any impurities such as carbon deposits. This not only cleans the oil circuits but also improves the heat exchange efficiency, thereby increasing the COP. In China, applications such as those related to Sinopec and BASF have been around for a very long time; work on them has been ongoing ever since.