Engineering

"To find the heat transfer rate per unit length at surface 1, we can use the Stefan-Boltzmann Law, which states that the radiative heat transfer rate between two surfaces is proportional to the fourth power of the absolute temperature difference between them. The formula for radiative heat transfer rate per unit area is given by:

Q=εσ(T1 4 − T4 2)

Where:

Q is the heat transfer rate per unit area.

ε is the emissivity of the surfaces.

σ is the Stefan-Boltzmann constant.

T1 and T2 are the temperatures of the two surfaces.

Since the surfaces are diffuse and gray, we assume that they are in thermal equilibrium, and we can use the same formula to find the radiative heat transfer rate per unit area from surface 2 to surface 3. However, since surface 3 is well insulated, there is no heat transfer through it."