Interactive Self-Study Module: Throttling and Joule-Thomson Expansion


This module uses screencasts and interactive simulation(s) to explain throttling (Joule-Thomson expansion) of single-component liquids and gases. When a mixture is throttled, the liquid and vapor compositions are different, and this is a basis for separations; see the Flash Separations module. Your retention of material in this module will increase if you write down reasons for your answers to ConcepTests, questions in screencasts, and questions to answer before using interactive simulation(s), and you try to solve the example problems before watching the solutions in the screencasts. 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 Joule-Thomson expansion and answer the questions within the screencasts.
  3. Review important equations for throttling and Joule-Thomson expansion.
  4. Use the interactive simulation(s) to further understand throttling and Joule-Thomson expansion.
  5. Try to solve the example problems before watching the solutions in the screencasts.
  6. Answer the ConcepTests.
  7. Look at the list of key points, but only after you try to list the key points yourself.
  • Throttling or Joule-Thomson expansion results in a temperature change when a high-pressure liquid or ideal gas undergoes an adiabatic pressure drop. For most gases the temperature decreases. For most liquids, the temperature drops as some of the liquid evaporates.
  • This module is intended for a thermodynamics course.
Before studying this module, you should be able to:
After studying this module, you should be able to:
  • Determine the outlet conditions for a throttle, given the inlet pressure and temperature, the outlet pressure, and an equation of state or a table of properties.