Effect of moisture and non-condensable gases on refrigeration equipment

In the refrigeration system, the refrigerant contains various foreign substances such as water, non-condensable gas, refrigeration oil, metal chips, grease, fibers, dust, etc., which have a great impact on the refrigeration equipment. As a refrigerant, you should know about the undesirable phenomena caused by the presence of foreign substances and how to eliminate them.
1. The influence of moisture
The moisture in the system has a very bad impact on the equipment, generally the water and the refrigerant interact with each other to corrode the metal, and at the same time emulsify the lubricating oil, in the low pressure part of the small channel, sometimes the moisture can freeze and block the channel. If there is moisture in the freon system, it will not only create ice blockages, but also make the system not work properly.
Measures to prevent moisture from entering the system
1. When using air for air tightness test, dry gas and non-combustible gas should be used as much as possible, such as carbon dioxide or nitrogen;
2. Choose a refrigerant that meets the standard;
3. Choose refrigeration oil that meets the standards;
4. There shall be no leakage in the system, especially in the vacuum, to prevent air intrusion;
5. When disassembling the machine, it is best to keep the machine room dry to prevent steam from entering the machine.
2. The effect of non-condensable gases
The non-condensable gas in the system, most of the time is produced by the air intrusion and the gas decomposed by oil at high temperature, due to the existence of non-condensable gas in the system, the condensation pressure increases, the exhaust temperature rises, the refrigeration capacity is reduced, and the power consumption is increased, especially when ammonia is used as a refrigerant, due to the presence of non-condensable gas, it is often necessary to pay attention to the venting of non-condensable gas in the system. Generally, the air is discharged through an air separator.
Measures to prevent non-condensable gases from entering the system:
1. Before filling the refrigerant, the system should be made to reach a high vacuum;
2. After the equipment is disassembled and installed, it should be vacuumed;
3. The system is strictly anti-leakage.
3. The impact of refrigeration oil
Although the refrigeration system is separated by the oil separator, there is still part of the oil into the intercooler, condenser, liquid reservoir and evaporator, etc., due to the oil in the equipment, the oil film is generated on the inner surface of the equipment to increase the thermal resistance, so that the heat exchange deteriorates, and affects the performance of the equipment.
Due to the difference in the specific gravity of liquid refrigerant and oil, the oil accumulation is generally stored in the lower part of the equipment, if there is a concave and convex place on the suction pipeline, the oil accumulates in the concave place, which narrows the gas path and increases the resistance of gas flow. In addition, when the exhaust temperature is too high, the oil quality deteriorates, and it is easy to carbonize around the compressor valve, and carbon deposition will hinder the operation of the valve.
Pay attention to the following when installing:
1. Iron filings, dust, sediment, oxides, etc. in the equipment and pipelines should be completely removed;
2. Remove stagnant water in various equipment;
3. Remove the grease and other foreign matter coated for rust prevention inside the machine;
4. For the newly installed equipment, the suction filter, dry filter, and suction filter, oil filter, crankcase, etc. in the system should be cleaned frequently.