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Heat transfer

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(Conduction)
Line 11: Line 11:
:<math>Q = \mbox{Heat conducted}\;[W]</math>
:<math>Q = \mbox{Heat conducted}\;[W]</math>
:<math>k = \mbox{Thermal conductivity of the material}\;[W/m\,K]</math>
:<math>k = \mbox{Thermal conductivity of the material}\;[W/m\,K]</math>
-
:<math>A = \mbox{Cross-sectional area of the object parallel to heat conduction}\;[m^2]</math>
+
:<math>A = \mbox{Cross-sectional area of the object perpendicular to heat conduction}\;[m^2]</math>
:<math>T = \mbox{Temperature}\;[K]</math>
:<math>T = \mbox{Temperature}\;[K]</math>
:<math>x = \mbox{Length of the object}\;[m]</math>
:<math>x = \mbox{Length of the object}\;[m]</math>

Revision as of 04:29, 2 December 2005

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]

Convection

Radiation

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