Steam Turbines and Air Compressors — Lesson - 3

This lesson covers the solution to a complex problem involving an insulated 5m cube rigid tank containing air. The air is allowed to escape until the pressure inside drops, while the temperature is maintained constant using an electrical resistance heater. The lesson explains how to calculate the electrical energy supplied during the process and the total entropy change. It also discusses how to solve the problem by considering a control volume and applying the laws of thermodynamics. For instance, the lesson uses the first law for control volume and mass conservation to derive equations for the problem. The lesson also provides a detailed explanation of how to integrate these equations to find the solution.

Video Highlights

02:50 - Explanation of the control volume including the electric resistance heater
06:23 - Integration the equation to find the electrical work supplied during the process
09:21 - Explanation of how to find the entropy balance
17:00 - Application of the first law to find the amount of liquid that has gone out and the entropy generation
23:09 - Explanation of how to find the entropy balance

Key Takeaways

- The first law of thermodynamics, mass conservation, and entropy balance are crucial in solving problems involving insulated tanks.
- In a process where the tank discharges its mass, causing the pressure to decrease, electrical work is applied to maintain the temperature.
- The electrical energy supplied during the process and the total entropy change can be calculated using the principles of thermodynamics.
- The quality of the steam in the tank in the initial state can also be determined using these principles.