Heat Transfer-1 (color)

– Heat Transfer via Free Electrons:
This second conduction heat transfer mechanism is observed
primarily in metallic solids. The concentration of free electrons
varies considerably for metallic alloys and is very low for nonmetals.
The previous statement implies that the ability of solids
to conduct heat via this mechanism varies directly with the free
electron concentration (pure metals conduct heat the best). This
conduction mechanism also relies on the existence of a
temperature gradient.
• Theoretical Treatment of Heat Transfer by Conduction
A quantitative expression relating the rate of heat transfer, the
temperature gradient and the nature of the conducting medium
is attributed to Fourier (1822)
q x dT
= − k temperature
A dx gradient along x
Heat flux= heat thermal
flow rate per unit conductivity
area in direction x of material
A: area normal to
heat flow