HVAC Design

Psychrometric Processes


In HVAC design the fundamental requirement is to identify the processes that is being performed on the air. These processes can be plotted on a psychrometric chart.

A psychrometric chart is a graphical representation of the thermodynamic properties of moist air at a pressure of one atmosphere. Using this chart, engineers can solve problems without having to do long and tedious calculations.

The psychrometric charts shows the quantities of:

  • dry bulb temperature
  • wet bulb temperature (also known as saturation temperature)
  • dew point temperature
  • relative humidity
  • moisture content (also known as humidity ratio)
  • enthalpy (also known as total heat)
  • specific volume (the inverse of density)