Radiation Shielding of a Spherical Black Body
This Demonstration shows how a radiation shield affects radiative heat transfer to a ball. The ball, in the center of an enclosure, is the object that is shielded; you can remove the shield by unchecking "shield". The enclosure around the shield and ball is assumed to be a black body at a temperature of 600 K. The radiation shield diameter is 0.2 m larger than the ball diameter, and the shield is thin enough that conductive heat transfer can be ignored. Use buttons to view a radiation network or a plot of the radiative heat transfer from the enclosure to the ball as a function of the emissivity of the shield. The plot is available only when "shield" is checked and a 3D physical representation of the ball and shield is shown on the plot.
Contributed by: Mathew L. Williams (June 2014)
Additional contributions by: Rachael L. Baumann
University of Colorado Boulder, Department of Chemical and Biological Engineering
Open content licensed under CC BY-NC-SA
The radiative heat transfer is calculated using a relation between the temperatures of the ball and enclosure over the sum of the resistances:
where is in , is the Stefan–Boltzmann constant (), and are the wall and ball temperatures (K) and is thermal resistance ().
The resistance from enclosure to shield is:
The resistances associated with shield emissivity are:
The resistance between the shield and ball is:
The resistance associated with the ball emissivity is:
where is surface area (), is diameter (m) and is emissivity.
 T. L. Bergman, A. S. Lavine, F. P. Incropera and D. P. DeWitt, Introduction to Heat Transfer, 6th ed., Hoboken, NJ: John Wiley and Sons, 2011.