"Cooling capacity" is a common term in the field of refrigeration. To achieve a lower temperature than the environment, it is necessary to rely on refrigeration and electricity consumption. Extracting heat from low-temperature objects comes at a cost. Due to its temperature being lower than the ambient temperature, it has the ability to spontaneously absorb heat from the environment. The maximum capacity it can absorb heat is the amount of heat it can absorb when its temperature is raised to ambient temperature. The magnitude of this heat absorption capacity is called cooling capacity.
The lower the temperature and the more quantity of an object, the greater its ability to absorb heat, which is called having more cooling capacity. In terms of quantity, it is equal to the heat taken from low-temperature objects during refrigeration, and also equal to the heat that low-temperature objects can absorb (both based on ambient temperature). To achieve a lower temperature than the environment through artificial methods, it requires a certain amount of energy consumption (work, electricity, etc.). This process is called "cooling".
In an oxygen concentrator, the air temperature needs to be lowered to the liquefaction temperature, which is also a refrigeration process. Therefore, a compressor must be installed at the cost of consuming electrical energy. However, in the oxygen concentrator, air is used as the working fluid, and the purpose of cooling is achieved by compressing and then expanding the air. Then cool the air itself again until it reaches the liquefaction temperature and is liquefied.
