Basic constitutive equations
Conduction through a circular wall
Heat flows through a circular wall with inner radius r_{i} and outer radius r_{o} as illustrated to the right: | |
The rate of heat flow Q [W] over the area A [m^{2}] and an infinitesimal thickness dr [m] of the wall may be written as: | |
where λ [W/m·K] is the wall thermal
conductivity. This equation is known as Fourier's law of conduction. | |
Integrating for a wall thickness (r_{o} - r_{i}) with boundary temperatures T_{1} and T_{2} gives: | |
The temperature profile is hence a logarithmic curve. | |
For thin walls the equation for a plane wall may be applied. |
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