This Demonstration shows how radiation shields affect radiative heat transfer to a ball. The ball in the center is the object that is shielded; you can remove the shield by unchecking the shield control checkbox. The enclosure around the shield and ball is assumed to be a black body at a temperature of 600 K. The diameter of the radiation shield is always 0.2 m larger than the diameter of the ball, and the shield is assumed thin enough that conductive heat transfer can be ignored. Three views are possible: a 3D physical representation, a radiation network, and a plot of the radiative heat transfer from the enclosure to the ball as a function of the emissivity of the radiation shield. The emissivity of the radiation shield can be adjusted to match emissivities of targeted materials.
The radiation network schematic tab shows the resistivities involved in this process. is the resistance from the enclosure to the shield. and are the resistances associated with the emissivity of the shield. is the resistance between the shield and the ball, and is the resistance associated with the emissivity of the ball. The radiative heat transfer is calculated using a relation between the temperatures of the ball and enclosure over the sum of the resistances, shown below.