Cold storage installations in my country mainly use two kinds of refrigerants, ammonia liquid and fluorine liquid, but with the progress of society, science and technology are becoming more and more advanced. Nowadays, ammonia liquid is used most in cold storage installation projects because it is cheap and has good cooling effect, but it is poisonous and easy to burn. Then let’s take a look at the advantages and disadvantages of this ammonia refrigerant.
Beginning in the 1970s, my country began to use ammonia liquid for refrigeration as a strategic reserve of frozen and refrigerated food for cold storage installation projects. In the early days of cold storage, there was no other choice but ammonia liquid refrigeration. Ammonia liquid refrigeration has become the only required equipment as a cold storage refrigeration equipment.
Today we first talk about the advantages and disadvantages of ammonia liquid refrigeration cold storage:
The advantages of ammonia liquid as a refrigerant are: relatively easy to purchase, low price during operation, moderate pressure, large unit refrigeration capacity, very good refrigeration effect, high heat release coefficient, almost insoluble in oil, low flow resistance, and leakage Easy to find. At present, ammonia liquid refrigeration can still be used as a refrigerant and has not been eliminated. The main features are wide sources, low prices, and relatively mature traditional technologies.
The disadvantage of ammonia liquid as a refrigerant is: the ammonia liquid itself has a pungent odor, and contains toxic components, will cause combustion and explosion when encountering sudden changes in high temperature, and has a corrosive effect on copper and copper alloys. In the past few years, the explosion of the Jilin cold storage and the ammonia leakage of the Shanghai cold storage have all shown that the ammonia refrigeration is gradually being phased out. This is also for the inevitable trend.
Ammonia has very good water absorption, even at low temperatures, water will not precipitate from the ammonia solution and freeze, so there will be no “ice plug” phenomenon in the system. Hong Kong and China Cold Storage Installation Company reminded that ammonia has no corrosive effect on steel, but after ammonia liquid contains water, it has corrosive effect on copper and copper alloys, and slightly increases the evaporation temperature. Therefore, copper and copper alloy materials cannot be used in ammonia refrigeration devices, and it is stipulated that the water content in ammonia should not exceed 0.2%. The specific gravity and viscosity of ammonia are small, the heat release coefficient is high, the price is cheap, and it is easy to obtain. However, ammonia has strong toxicity and flammability. In terms of volume, when the content of ammonia in the air reaches 0.5% to 0.6%, people can be poisoned by staying in it for half an hour. When it reaches 11% to 13%, it can be ignited. When it reaches 16%, it will explode when exposed to an open flame. . Therefore, the ammonia refrigerating machine room must pay attention to ventilation and exhaust, and often need to remove the air and other non-condensable gases in the system.
The installation of cold storage in my country still accounts for most of the refrigeration at this stage, but with the advancement of technology, fluorine refrigerant will also be continuously improved, and the use will become more and more common.