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 A x (T_{1}^{4} - T_{2}^{4})

Where 56.69x10^{-9} is the average Stefan-Bolzmann
constant, *A*
is the area of the plate, *T _{1}* is the plate 1 temperature
and

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

x = L / D

y = W / D

Where * L* is the plate length, * W* is the plate width, and
* D* is
the distance between the plates.

**References**

Ellison G. N., *Thermal
Computations for Electronic Equipment*, Van Nostrand Reinhold Company, New
York, 1984. p. 78 - 79.

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