In the book, the air treatment processes in the air conditioning systems are given. The new corrected method is developed for the calculation of heat and humidity treatment of air by water, where is taking into account not only the heat transfer process between water and air but also the mass transfer process. That is, in the chamber take place sensible and latent heat exchange processes and as well as the mass transfer of water vapour. As a result, both air and water change their parameters, that is, they move from one state to another. The state of air is mainly characterized by its temperature, humidity, relative humidity, and enthalpy, through which these states are represented on the humid air psychrometric chart or The Mollier diagram. The main equipment for evaporating cooling is an air irrigation chamber, so the construction schemes and design characteristics are given, and also shown the necessary processes on the air Enthalpy-Humidity (h-d) diagram. The book is useful for engineers, designers, researchers, and students of energy.