The rudimentary basis for understanding any air conditioning, dehumidification and evaporative cooling is psychrometrics. Psychrometry consists of the interactions between heat, moisture and air. It is basically the study of air-water mixtures and is an essential foundation for understanding how to change air from one condition to another. As air temperature rises, its capacity to hold moisture also rises, and warmer air becomes less dense. This makes moisture a very influential factor for heat gain, both for comfort and in calculations. The knowledge of systems consisting of dry air and water vapor is essential for the design and analysis of air conditioning devices, cooling towers, and industrial processes requiring close control of the vapor content in air. Air moisture and heat interactions are rather complex; fortunately, these interactions can be combined in a single chart. However before explaining the details of how to use the chart, some terms, definitions, and principles used in the study of systems a brief review about the system and the processes involved is given in order for better understanding.
While in our evaporative cooler we have introduced another process which involves a heating process leading to decrease in the relative humidity and increase in dry bulb temperature thus providing the optimum conditions for an evaporative cooler to work efficiently and produce optimum cooling effects. The inlet air is ambient air that enters the cooler from the single entry side and thus enters to the first stage of the cooler i.e sensible heating with the help of heating rods thus reducing the relative humidity to comfort level and also increasing the dry bulb temperature. After sensible heating the heated air passes through the filter media through which evaporative cooling effect is produced and hence optimum cooling effects are produced.