Refrigerated Air Dryer

They are used to remove the humidity in the compressed air, by cooling the air the water removed from the humidity is then sent to a drain drying the air. The dryer is nothing more the a refrigeration unit.

you recently registered and started shooting of nonsense questions.

why dont you get off your seat and do some reading.

Having no perception of your background it is difficult to have a clear vision of your question. Basically you are asking about air conditioning of a compressed air system. The answer to your question is completely covered in the study of psychometrics.^{Psychrometries (derived from the Greek: psukhros = cold) is study of air-water vapor mixtures at different conditions. To quote the 1989 ASHRAE Handbook of Fundamentals, "Psychrometries deals with the thermodynamic properties of moist air and uses these properties to analyze conditions and processes involving moist air." Not knowing your background}