Calculation of Exergy — Lesson 2

This lesson covers the concept of exergy, a measure of the maximum useful work that can be extracted from a system. It explains how exergy is calculated and how it changes during different processes. The lesson also discusses the concept of entropy and its relationship with exergy. It further elaborates on the concept of work and heat transfer in relation to exergy. The lesson provides illustrative examples such as a tank of air at a certain pressure and temperature, and a steel casting cooling to room temperature, to explain how exergy changes in these scenarios.

Video Highlights

03:17 - Concept of exergy and its application in defining efficiency for any process
07:26 - Exergy of the air in the tank can be calculated using the equation of state
13:45 - Concept of specific exergy for a flow process
15:18 - Explanation of how the exergy of an isolated system decreases or remains the same.
25:30 - Concept of exergy transfer due to heat interaction

Key Takeaways

- Exergy is a measure of the maximum work that can be developed from a system.
- The generation of entropy in the universe is due to internal and external irreversibilities.
- The exergy of a system changes when heat or work is added or removed from the system.
- The calculation of exergy involves considering the system's initial and final states and the changes in its internal energy, volume, and entropy.
- The concept of exergy is crucial in defining efficiency for any process while taking into account the entropy generated in the universe as a result of the process.