The refrigerant of centrifugal refrigeration unit mainly uses Freon R11, R134A, R123 and so on. The performance changes of refrigerant can be described from three aspects: refrigerant and water, refrigerant and lubricating oil, refrigerant and metal and non-metal.
(1) Refrigerant and water, in the refrigeration system with Freon as refrigerant, when the refrigeration temperature is below 0 ℃, the free water will freeze and block the throttle channel, and cause insufficient liquid supply in the system, and the cooling capacity of the unit decreases; In addition, the water dissolved into the refrigerant will occur water decomposition phenomenon, and produce acidic substances, corrosion of metal materials, reduce the electrical insulation performance of the winding.
(2) The solubility of refrigerant and lubricating oil is different from that of refrigerant and lubricating oil, which is generally intersoluble or insoluble. When the intersolubility, the lubricating oil can penetrate into the various components of the compressor together with the refrigerant, forming good lubrication conditions and prolonging the operating life of the unit, but the intersolubility will reduce the viscosity of the lubricating oil, and the evaporation temperature of the unit will rise under the same pressure; When insoluble, refrigerant and lubricating oil are easy to separate, but the formation of oil film on the heat transfer surface and the inner surface of the unit will reduce the heat transfer coefficient.
(3) When refrigerant and metal and non-metal halogenated hydrocarbon contain water, hydrolysis will form acidic substances, which have corrosive effect on metal. Therefore, the mixture of water-containing refrigerant and lubricating oil can dissolve copper, forming copper plating phenomenon. Copper plating will affect the sealing condition of the moving parts, damage the bearing and then affect the overall sealing performance of the negative pressure unit, so that the outside air enters the unit, resulting in abnormal condensation pressure is too high; At the same time, halogenated hydrocarbon is also a good organic solvent, will make the polymer materials (such as natural rubber, resin, etc.) soft, expand or produce bubbles.
