Exergy Balance for Fixed Mass Systems — Lesson 1

This lesson covers the concept of exergy balance for fixed mass systems. It explains how to solve problems related to exergy balance using given properties such as initial and final states, work input, and surrounding conditions. The lesson provides a step-by-step solution to three different problems, each with varying conditions and requirements. For instance, the first problem involves a piston-cylinder device containing air, the second problem deals with a piston-cylinder device containing refrigerant, and the third problem involves a rigid tank divided into two equal parts. The lesson also explains how to calculate the exergy destroyed during the process and the second law efficiency.

Video Highlights

03:44 - Calculation of the specific volume for the state ambient
09:04 - Explanation of the minimum work and second law efficiency
11:04 - Introduction to the problem involving a piston cylinder device
21:23 - Introduction to the problem involving a rigid tank divided into two equal parts
28:01 - Explanation of the first law for the entire tank

Key Takeaways

- Exergy balance for fixed mass systems involves calculating the exergy at initial and final states, the minimum useful work required for a process, and the second law efficiency of the process.
- Specific exergy can be calculated using the properties of the system at the initial and final states.
- Exergy destruction is calculated using the first law for the entire system and entropy balance.
- The irreversibility in a process leads to a loss of work, which can be calculated as the product of entropy generated and the temperature.