This page calculates the net radiant heat exchange for two isothermal (constant temperature) parallel flat black plates of equal size.

The heat flow *(q)* from the plate is calculated as:

q = 56.69x10^{-9} x VF_{(1-2)} x L_{1}
x W (T_{1}^{4} - T_{2}^{4})

Where 56.69x10^{-9} is the average Stefan-Bolzmann
constant, *L _{1}* is the length of plate 1,

Where * x*, *y*, and *z* are defined as:

x = L_{1} / W

y = L_{2} / W

z = x^{2} + y^{2}

Where * L _{1}* is the plate 1 length,

**References**

Ellison G. N., *Thermal
Computations for Electronic Equipment*, Van Nostrand Reinhold Company, New
York, 1984. p. 78 - 80.

Holman, J.P., *Heat Transfer*, 7th ed., McGraw Hill
Book Company, New York, 1990. p. 385 - 405.