radiation network analysis

RADIATION NETWORKS:

IRRADIATION (G)  

Irradiation (G) is defined as the total thermal radiation incident upon a surface per unit time per unit area (in W/m²)

RADIOSITY (J):

The total thermal radiation leaving a surface per unit time & per unit area is called radiosity of the surface.

J = Emitted Energy + Reflected Part of Incident energy,

The net radiation heat exchange between the surface & all of its surroundings is given by,

The equivalent radiation circuit is,

Radiation heat exchange between two finite surfaces:

,The equivalent radiation circuit is

This space resistance shall exist in the space between two surfaces exchanging heat by radiation.

Complete radiation network between two surfaces exchanging heat by radiation:

Therefore,

APPLICATIONS OF RADIATIONS NETWORKS:

(i) Radiation Exchange Between two Infinitely Large Plane Surfaces:

(ii) TWO INFINITELY LONG CYLINDERS:

 

Therefore,

RADIATION SHIELDS:

F₁₂ = 1, F₂₁ = 1

 

Since surfaces are very large

A₁ = A₂ = A₃ = 1 and F₁₃ = 1, F₃₂ = 1

Therefore,