ABSTRACT
Psychrometry is the study of the changes in the state and content of moist air or humid air in applications such as heating, ventilation and air-conditioning, drying and cooling towers used in thermal power plants. It is well known that atmospheric air usually contains some amount of water vapor, which is colloquially referred to as humidity. The water vapor in the room air is superheated on account of the fact that its partial pressure is quite small. Furthermore, in psychrometric applications, the air is usually at a pressure of 1 atm or slightly higher and the range of temperature is typically between 0°C and about 60°C. Application of first law to psychrometric process is quite straightforward, since moist air is being treated as just a mixture of two ideal gases, namely, air and water vapor.
