Radiation in Enclosures — Lesson 4

This lesson covers the concept of radiative heat transfer, focusing on the empirical method for finding shape factors used in the industry for complex shapes. It explains how to calculate shape factors empirically, particularly for objects with compact shapes. The lesson also delves into the estimation of radiative properties of surfaces, such as emissivity, absorptivity, and reflectivity. It further discusses the concept of radiative transfer in enclosures, which are a series of surfaces enclosing a given area. The lesson concludes with an exploration of radiative transfer between non-black surfaces and the use of shields in temperature measurement to reduce error.

Video Highlights

03:26 - Introduction to radiative transfer in enclosures
11:14 - Explanation of the concept of thermal resistance to radiation with an example of two parallel black infinitely long plates,
33:56 - Discussion of the concept of radiosity with an example of two infinite parallel plates,
41:57 - Explanation of the concept of thermocouple shield with an example,

Key Takeaways

- Shape factors can be calculated empirically for complex shapes, which is particularly useful when standard expressions are not easily available.
- The radiative properties of surfaces, such as emissivity, absorptivity, and reflectivity, can be estimated.
- Radiative transfer occurs in enclosures, which are a series of surfaces enclosing a given area.
- Radiative transfer can occur between non-black surfaces, making the problem more realistic.
- Shields can be used in temperature measurement to drastically reduce the error introduced by radiative transfer.