# Heat transfer

(Difference between revisions)
 Revision as of 12:40, 1 December 2005 (view source)Jola (Talk | contribs)← Older edit Revision as of 04:29, 2 December 2005 (view source) (→Conduction)Newer edit → Line 11: Line 11: :$Q = \mbox{Heat conducted}\;[W]$ :$Q = \mbox{Heat conducted}\;[W]$ :$k = \mbox{Thermal conductivity of the material}\;[W/m\,K]$ :$k = \mbox{Thermal conductivity of the material}\;[W/m\,K]$ - :$A = \mbox{Cross-sectional area of the object parallel to heat conduction}\;[m^2]$ + :$A = \mbox{Cross-sectional area of the object perpendicular to heat conduction}\;[m^2]$ :$T = \mbox{Temperature}\;[K]$ :$T = \mbox{Temperature}\;[K]$ :$x = \mbox{Length of the object}\;[m]$ :$x = \mbox{Length of the object}\;[m]$

## Conduction

Conduction can be defined as the heat transfer through a substance because of a temperature gradient. The rate of heat transfer by conduction between two regions of a substance is proportional to the temperature difference between them. The constant of propotionality is called thermal conductivity of the material.

Mathematically, it can be described by using the Fourier's law:

$Q_{Conduction} = -k*A*\frac{dT}{dx}$

Where

$Q = \mbox{Heat conducted}\;[W]$
$k = \mbox{Thermal conductivity of the material}\;[W/m\,K]$
$A = \mbox{Cross-sectional area of the object perpendicular to heat conduction}\;[m^2]$
$T = \mbox{Temperature}\;[K]$
$x = \mbox{Length of the object}\;[m]$