This preview shows pages 1–15. Sign up to view the full content.

Chapter 13 Radiation Exchange Between Surfaces

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
The View Factor (also Configuration or Shape Factor) The view factor, is a geometrical quantity corresponding to the fraction of the radiation leaving surface i that is intercepted by surface j . ij F , i j ij i i q F A J = The view factor integral provides a general expression for F ij . Consider exchange between areas . ij F i j dA and dA : 2 1 i j i j ij i j A A i F dAdA A R θ π = ∫ ∫ cos cos 2 i j i j i i i j i i i j dq I dAd J dAdA R ϖ - = = cos cos cos

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
P. 13.106
Radiation Shields High reflectivity (low ) surface(s) inserted between two surfaces for which a reduction in radiation exchange is desired. α ε = Consider use of a single shield in a two-surface enclosure, such as that associated with large parallel plates: Note that, although rarely the case, emissivities may differ for opposite surfaces of the shield.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Radiation Network: ( 29 4 4 1 2 12 1 2 31 3 2 1 2 1 1 1 13 31 3 3 2 3 3 32 2 2 1 1 1 1 1 1 T T q q q A A F A A A F A σ ε - = = - = - - - - + + + + + , , , , The foregoing result may be readily extended to account for multiple shields and may be applied to long, concentric cylinders and concentric spheres, as well as large parallel plates.

This preview has intentionally blurred sections. Sign up to view the full version.

View Full Document
Directional Considerations and the Concept of Radiation Intensity Radiation emitted by a surface will be in all directions associated with a hypothetical hemisphere about the surface and is characterized by a directional distribution. Direction may be represented in a spherical coordinate system characterized by the zenith or polar angle and the azimuthal angle .
This is the end of the preview. Sign up to access the rest of the document.

{[ snackBarMessage ]}