The symbol (f) is a dimensionless factor
sometimes called the radiation
configuration factor,
which takes into account the
emissivity of both bodies and their relative geometry. The
radiation configuration
factor is usually found in a text book for the given
situation. Once the configuration
factor is obtained, the overall net heat flux can be
determined. Radiant heat flux should
only be included in a problem when it is greater than 20% of
the problem.
Example:
Calculate the radiant heat between the floor
(15 ft x 15 ft) of a furnace and the roof, if the
two are located 10 ft apart. The floor and roof temperatures
are 2000°F and 600°F, respectively.
Assume that the floor and the roof have black surfaces.
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