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Heat transfer by radiation

The Radiative Heat Transfer block represents a heat transfer by radiation between two bodies. The transfer is governed by the Stefan-Boltzmann law and is described with the following equation:

where

Q | Heat flow |

k | Radiation coefficient |

A | Emitting body surface area |

T_{A}, T_{B} | Temperatures of the bodies |

The radiation coefficient is determined by geometrical shapes, dimensions, and surface emissivity. For example, the radiation constant for the heat transfer between two parallel plates is computed as

where

σ | Stefan-Boltzmann constant |

ε_{1}, ε_{2} | Surface emissivity for the emitting and receiving plate, respectively |

Similarly, the radiation coefficient for concentric cylinders is determined with the formula

where *r*_{1} and *r* _{2}
are the emitting and receiving cylinder radii, respectively. Reference
[1] contains formulas
for a wide variety of shapes.

Connections A and B are thermal conserving ports associated with the emitting and receiving bodies, respectively. The block positive direction is from port A to port B. This means that the heat flow is positive if it flows from A to B.

**Area**Radiating body area of heat transfer. The default value is

`0.0001`m^2.**Radiation coefficient**Radiation coefficient of the two bodies, based on their geometrical shapes, dimensions, and surface emissivity. See [1] for more information. The default value is

`4e-8`W/m^2/K^4.

Use the **Variables** tab to set the priority
and initial target values for the block variables prior to simulation.
For more information, see Set Priority and Initial Target for Block Variables.

[1] Siegel, R. and J.R. Howell. *Thermal Radiation
Heat Transfer*. New York: Taylor and Francis, 2002.

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