How much do you know about the refrigerant used in domestic freeze dryers?

　　The freeze dryer is based on the principle of air freeze-drying. The refrigeration equipment is used to cool the compressed air to a certain dew point temperature, and the corresponding moisture is deposited, and the gas-liquid separation is performed by the separator, and then the water is discharged by the automatic drain valve. Thereby achieving the purpose of freezing and dehumidification. At the same time, the solid dust particles and micro-oil content of 3μ and above in the compressed air are filtered out, so that the quality of the gas source can be cleaned and dried.

　　The work of the freeze dryer is divided into two parts: the air system and the refrigeration system:

　　Air system:

　　The compressed air containing moisture and oil enters the gas-to-gas heat exchanger to pre-cool the compressed air, reduce the temperature of the compressed air, remove a part of the moisture, and then enter the gas-to-refrigerant heat exchanger to cool the compressed air to (2-10) Dew temperature of 0C. Moisture, oil and some impurities are condensed here. The cooled gas and the condensed water, oil and some impurities are separated by the gas-liquid separator, and then the water and oil are discharged by the automatic drain valve. The compressed air is heated and output through the gas-to-gas heat exchanger, thereby effectively preventing the "sweating" phenomenon of the pipeline.

　　Cooling System:

　　The low-temperature liquid refrigerant absorbs heat in the gas-to-refrigerant exchanger and evaporates into a gaseous state. The gaseous refrigerant enters the suction port of the refrigeration compressor from the refrigerant outlet of the exchanger through the vaporizer and the suction filter, and the vaporizer and the suction filter are In order to prevent liquid refrigerant and impurities from entering the compressor, the compressor compresses the low-temperature and low-pressure refrigerant into high-temperature and high-pressure gas. According to the automatic adjustment of the bypass valve, a small portion of the gas directly enters the gas-to-refrigerant heat exchanger. Most of the gas enters the condenser to condense and cool down. The low temperature liquid refrigerant from the condenser enters the expansion valve through the reservoir and the drying filter. The role of the reservoir and condenser is to ensure that the refrigerant is in a pure liquid state at the inlet of the expansion valve. The liquid refrigerant expands into the gas-to-refrigerant heat exchanger and cools the compressed air in the exchanger, which in turn begins a new cycle.

　　As the load increases, the pressure of the refrigerant in the refrigerant heat exchanger increases, and the expansion port is opened by the expansion valve sensor signal until a new equilibrium is reached.

　　When the load is too small, the bypass valve automatically supplies an artificial load to the gas-to-refrigerant heat exchanger to prevent the suction pressure from being too low.

　　For the refrigerant used in domestic freeze dryers:

　　1. The refrigerant is poured too little, and the chance of cold drying appears:

　　1 The evaporation pressure and condensing pressure are lower than normal operation, but the air dew point cannot be lowered;

　　2 The compressor casing is hot.

　　2. If the refrigerant is poured too much, the chance of cold drying will appear:

　　1 Because the refrigerant liquid stores two condensers, the condensation area is reduced, resulting in an increase in the condensing pressure, causing a high voltage trip in severe cases;

　　2 The refrigeration compressor load is increased and the starting is difficult;

　　3 The refrigerant is not completely vaporized in the evaporator, so that the wet steam enters the compressor, and there is a danger of "liquid compression";

　　4 As the condensing pressure increases, the compressor cooling capacity is reduced and the air dew point is increased.

　　Which kind of refrigerant is used in the domestic freeze dryer?

　　At present, most of the domestically produced cold-drying machines use R22 as a refrigerant.

　　Features: no burning, no explosion, colorless, odorless, low toxicity, is a safe refrigerant;

 freeze dryer :

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