#### Interactive Self-Study Module: Liquefaction

##### Overview:

This module uses screencasts to explain liquefaction processes. It then provides example problems to allow the user to test themselves. Your retention of material in this module will increase if you write down reasons for your answers to ConcepTests and questions in screencasts, and you try to solve the example problems before watching the screencast solutions. We suggest using the learning resources in the following order:

- Attempt to answer the multiple choice ConcepTest and solve the example problem before watching the screencasts.
- Watch the screencasts that describe the liquefaction process and show the processes on P-H and T-S diagrams and then answer the questions within the screencast.
- Review important equations for liquefaction processes.
- Try to solve the example problems before watching the solutions in the screencasts.
- Answer the ConcepTests.
- Look at the list of key points, but only after you try to list the key points yourself.

##### Motivation:

- Liquefaction processes are used to form low-temperature liquids such as liquid N
_{2}, CH_{4}, and H_{2}. - This module is intended for a thermodynamics course.

##### Before studying this module, you need to:

- Be aware that Equations of State can be used to determine thermodynamic properties.
- Be able to show processes on pressure-enthalpy and temperature-entropy diagrams: Thermodynamic Properties Phase Diagrams.
- Be able to apply an energy balance for Throttling and Joule-Thomson Expansion.
- Be able to apply the First Law – Open Systems to a steady-state system.
- Be able to determine output conditions from a reversible compressor: Turbines and Compressors.

##### After studying this module, you should be able to:

- Solve mass and energy balances for a liquefaction process to determine the fraction of fluid entering the Joule-Thomson expansion that is converted to liquid.
- Solve energy balances to determine the compressor work required to form one kg of liquid.
- Explain how gas is converted to liquid in a steady-state process.
- Draw a liquefaction cycle on a pressure-enthalpy diagram and a temperature-entropy diagram.