Question

An uninsulated steam pipe passes through a room in which the air and walls are at

20°C. The outside diameter of the pipe is 70 mm, and its surface temperature and
emissivity are 100°C and 0.8, respectively. What are the surface emissive power
and irradiation?

Answer 1

The surface emissive power of the steam pipe can be calculated using the Stefan-Boltzmann law. The irradiation can then be determined using the surface emissive power and reflectivity.

Step-by-step explanation:

The surface emissive power of the steam pipe can be calculated using the Stefan-Boltzmann law. The formula is:

Surface Emissive Power = emissivity * Stefan-Boltzmann constant * surface temperature^4

Plugging in the values, the surface emissive power would be:

Surface Emissive Power = 0.8 * 5.67 * 10^-8 * (373)^4

To calculate the irradiation, we can use the formula:

Irradiation = surface emissive power * (1 - reflectivity)

Given that the reflectivity is not mentioned in the question, we'll assume it is 0 (meaning no reflection). Therefore, the irradiation would be:

Irradiation = Surface Emissive Power * (1 - 0)