Isothermal Gas Enclosures — Lesson 10

This lesson covers the concept of estimating temperature profiles in radiating gases, with a focus on furnaces. It introduces the concept of radiation slip and explains how solutions differ in thin and thick limits. The lesson also discusses the importance of estimating fluxes in radiation occurring in a furnace and the role of temperature profiles in this process. It further explains the concept of isothermal gas enclosures and the calculation of radiation between surfaces. The lesson concludes with a detailed explanation of the Hottel's Well-Stirred furnace model and an example of calculating the efficiency of a power plant furnace.

Video Highlights

01:49 - Explanation of the concept of isothermal gas enclosures and the assumptions made in this context.
09:28 - Discussion on the concept of mean transmittance and mean emissivity of the gas.
21:33 - Introduction to Hottel’s Well-Stirred furnace model and its application.
30:12 - Explanation of the concept of adiabatic flame temperature and effective area of the furnace.
42:55 - Calculation of the heat transfer efficiency of a furnace using a real-life example.

Key Takeaways

- The temperature profile in a radiating gas can be estimated using integral equations.
- In furnaces, radiation plays a crucial role and the aim is to estimate fluxes rather than temperature profiles.
- The concept of isothermal gas enclosures simplifies the estimation of fluxes.
- The Hottel's Well-Stirred furnace model provides a simple way to estimate heat transfer in furnaces.
- The efficiency of a power plant furnace is not highly sensitive to the emissivity of the gases.