Interactive Self-Study Module: Humidity and Water-Air Vapor-Liquid Equilibrium (Psychrometric Chart)
Department of Chemical and Biological Engineering, University of Colorado Boulder 

This module uses screencasts and an interactive simulation to discuss vapor-liquid equilibrium for water in the presence of air. It explains how to use a psychrometric chart (humidity chart). It then provides example problems to allow the user to test themselves. We suggest using the learning resources in the following order:

  1. Attempt to answer the multiple-choice ConcepTest and solve the example problem before watching the screencasts or working with the simulations.
  2. Watch the screencasts that explain psychrometric charts and humidity.
  3. Use the interactive simulation to further understand psychrometric charts.
  4. Try to solve the two example problems before watching the solutions in the screencasts.
  5. Answer the ConcepTests.
        Vapor-liquid equilibrium for water and humidity are important in many applications.
        This module is intended for thermodynamics course or materials and energy balances course. 

Before studying this module, you should:

After studying this module, you should be able to:
  1. Use a psychometric chart to determine dry bulb temperature, wet bulb temperature, dew point temperature, relative humidity, and enthalpy.
  2. Predict behavior of two-phase systems with two components where only one component is in the liquid phase (air/water systems).
  3. Apply energy balances to vapor liquid equilibrium for air/water systems.
  4. Apply mass balances two air/water systems equilibrium.
  5. Use steam tables to determine equilibrium conditions for air/water systems.