1,2 • THE VIEW FACTOR 



Ratio, 



3 4 5 



side or diameter 

 distance between planes 



Fig. 1, 2b. View factor F and interchange factor F for opposed 

 parallel disks, squares, and rectangles. 



Fig. I,2c. 



Dimension ratio Z 



View factor F for direct radiation between adjacent 

 rectangles in perpendicular planes. 



is now SiFncTl; from ^2 to Si, it is S2F2KTTI; the net interchange is 

 their difference, which may be written as either SiFi2(t{T\ — Tf) or 

 S2F2i<T{Tt - Tl). One thus reaches the important conclusion that inter- 

 change may be obtained by evaluating the one-way radiation from either 

 surface to the other, whichever is more convenient, and then replacing 



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