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.

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DETAILS

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:
,
where .
The resistances associated with shield emissivity are:
,
.
The resistance between the shield and ball is:
,
where .
The resistance associated with the ball emissivity is:
,
where is surface area (), is diameter (m) and is emissivity.
Reference
[1] 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.
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