Entropy Change and Generation — Lesson - 2

This lesson covers the concept of entropy change and entropy generation in a control volume. It explains how to develop expressions for the change in entropy of a fluid across a control volume and the rate of entropy generation due to internal irreversibilities. The lesson also discusses the rate of entropy generation in the universe as a result of a process. It further elaborates on the concept of entropy transfer and entropy generation due to internal irreversibilities. The lesson also provides an understanding of how to calculate the entropy change of a system using tedious relations for ideal gases or using tabulated values of entropy.

Video Highlights

02:09 - Concept of entropy generation and its implications
05:34 - Performance metric of processes based on entropy generation
07:22 - First law applied to a control volume
17:10 - Entropy balance equation for steady flow devices

Key Takeaways

- Entropy change of a system is the sum of entropy change due to transfer from the surroundings and entropy generation due to internal irreversibilities.
- Entropy transfer can be greater than, equal to, or less than zero depending on the direction of heat transfer.
- Entropy generation is always positive or equal to zero. It is positive as a result of internal irreversibility such as friction, dissipation, and mixing.
- The rate of entropy generation in the universe is a crucial performance metric for processes. The lesser the entropy generated, the more desirable the process is.
- The entropy balance equation is a crucial tool in understanding the behavior of steady flow devices.