Classification Of Cryogenic Refrigerators

There are many classification methods for cryogenic refrigerators, for example, they can be classified according to their use, refrigeration medium or machine structure; they can also be classified according to their working temperature zone, cooling capacity and heat exchange method. If classified by cooling temperature, a cryogenic refrigerator refers to a machine or device that produces cooling capacity at a temperature below 120K. The size of the cooling capacity of the low-temperature refrigerator has a great relationship with the temperature at which the cooling capacity is provided. For example, an ideal refrigerator based on the Carnot cycle can provide 1W of cooling capacity at 120K and only need 29W of energy input; if it provides 1W of cooling capacity at 0.5K, it requires more than 20 times the energy of 600W. Moreover, the energy required by the actual refrigerator is often dozens or even hundreds of times larger than the theoretical value, because the refrigerator needs to overcome a number of irreversible losses during the actual working process, and these losses will be compensated by the theoretical cooling capacity of the refrigerator. Therefore, the available cooling capacity of the actual output of the cryogenic refrigerator is the difference between its theoretical cooling capacity and the sum of all the energy lost during the actual working process.