Psychrometric Chart

A psychrometric chart is a graphical representation of the thermodynamic properties of moist air at a constant pressure. It plots the relationships between dry bulb temperature, wet bulb temperature, dew point temperature, relative humidity, humidity ratio, enthalpy, and specific volume. HVAC engineers use psychrometric charts to analyze air conditioning processes such as heating, cooling, humidification, dehumidification, and mixing of airstreams. Each point on the chart represents a unique air state defined by any two independent properties. The chart is essential for understanding how air treatment processes move air from one state to another and for verifying that system designs will achieve the desired indoor conditions.