Poor cooling equipment There is a foreign body at work!

Poor cooling equipment There is a foreign body at work!

In the refrigeration system, the refrigerant contains various foreign substances such as moisture, non-condensable gas, refrigerating oil, metal shavings, grease, fiber, dust, etc. These foreign substances have a great impact on the refrigeration equipment. Therefore, everyone must know the undesirable phenomena caused by the presence of foreign objects and how to eliminate them.

　　 1. The influence of moisture

The moisture in the system has a very bad effect on the equipment. Generally, moisture and refrigerant interact with each other to corrode metals and emulsify lubricating oil. At the small passages in the low pressure part, sometimes moisture can freeze and block the passages, so ammonia refrigerant The water content should be ≤4%. If there is water in the Freon system, it will not only cause ice blockage, but also make the system unable to work normally.

　　 Measures to prevent moisture from entering the system

　　 1. When air is used for the air tightness test, dry gas and non-flammable gas, such as carbon dioxide or nitrogen, should be used as much as possible;

　　 2. Choose a refrigerant that meets the standard;

　　3. Choose refrigerating oil that meets the standard;

　　4. There should be no leaks in the system, especially in 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 influence of non-condensable gas

The non-condensable gas in the system is mostly produced by air intrusion and oil decomposed at high temperature. Due to the presence of non-condensable gas in the system, the condensing pressure and exhaust temperature rise, reducing the cooling capacity , Increase the power consumption, especially when ammonia is used as the refrigerant, the presence of non-condensable gas will often cause an explosion, so always pay attention to the emptying of the non-condensable gas in the system. Generally, air is discharged through an air separator. When there is no such equipment, after the compressor stops running, water is supplied to the condenser, the ammonia in the condenser is condensed into liquid, and the non-condensable gas gathers on the top of the equipment and can be discharged through the vent valve.

　　 Measures to prevent non-condensable gas from entering the system

　　 1. Before charging refrigerant, make the system reach high vacuum;

　　2. After the equipment is disassembled and installed, it should be vacuumed;

　　3. The exhaust temperature should not exceed 1500C;

　　4. The system shall strictly prevent leakage.

　　 3. The influence of refrigerating oil

Although the lubricating oil contained in the compressor discharge gas in the ammonia system is separated by an oil separator, some of the oil still enters the intercooler, condenser, liquid reservoir and evaporator, etc. Because of the oil in the equipment, The oil film on the inner surface increases the thermal resistance, worsens the heat exchange, and affects the performance of the equipment. Because of the difference in the specific gravity of liquid refrigerant and oil, oil generally accumulates in the lower part of the equipment. If there are bumps on the suction pipe, the oil will accumulate The recess narrows the gas passage and increases the gas flow resistance. Under the action of a certain pressure difference, the oil will suddenly return to the compressor, causing a liquid hammer accident. In addition, when the exhaust temperature is too high, the oil quality deteriorates, and it is easy to be carbonized around the compressor valve, and the carbon deposits will hinder the operation of the valve. Therefore, the operator should regularly discharge the oil in the refrigeration equipment and clean the compressor exhaust frequently. Gas valve.

　　 Freon systems generally dissolve fluorine and oil, and measures must be taken to bring the lubricating oil back into the compressor.

The foreign matter mentioned above can easily block the throttle valve or other narrow passages in the system, which will interrupt the circulation of refrigerant and the machine will be in an idling state. On the sealing surface, the machine or system's seal will be damaged. If it is light, it will leak a small amount of oil and gas, and it will not work in severe cases.

　　 When preparing for installation, pay attention to the following matters

　　 1. Iron filings, dust, silt, oxides, etc. should be removed from equipment and pipelines;

　　2, clear the accumulated water in various equipment;

　　3. Remove the grease and other foreign objects that are applied inside the machine for rust prevention;

　　4. For newly installed equipment, the ammonia filter, ammonia filter in the system, and the suction filter, oil filter, crankcase, etc. at all levels of the compressor should be cleaned frequently