Radiative Heat Transfer
Heat transfer by radiation
Library
Thermal Elements
Description
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 |
| TA, TB | 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 |
| ε1, ε2 | Surface emissivity for the emitting and receiving plate, respectively |
Similarly, the radiation coefficient for concentric cylinders is determined with the formula
where r1 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.
Variables
To set the priority and initial target values for the block variables prior to simulation, use the Variables tab in the block dialog box (or the Variables section in the block Property Inspector). For more information, see Set Priority and Initial Target for Block Variables.
Parameters
- Area
Radiating body area of heat transfer. The default value is
0.0001m^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-8W/m^2/K^4.
Ports
The block has the following ports:
AThermal conserving port associated with body A.
BThermal conserving port associated with body B.
References
[1] Siegel, R. and J.R. Howell. Thermal Radiation Heat Transfer. New York: Taylor and Francis, 2002.