A furnace consists of a 100 cm thick brick wall chamber in which gaseous material is combusted. The air surrounding the furnace chamber is at ambient temperature (25°C) and circulates due to natural convection with a value of the convection coefficient at 15 W/(m2.K). Assuming a thermal conductivity of 1 W/(m.K) for brick wall, which can be assumed a blackbody, calculate the of the furnace wall if the outer wall inner temperature of the furnace wall if the oute temperature reaches 80°C at steady-state.

Respuesta :

Explanation:

The heat transferred through conduction = heat transfer through radiation + heat transfer through convection

It is given that thermal conductivity of wall is 1 W/(m.K)

      Boltzmann constant ([tex]\sigma_{e}[/tex]) = [tex]5.68 \times 10^{-8} W/T^{4} m^{2}[/tex]  

Formula to calculate the inner temperature of the furnace is as follows.

       kA(T - 80) = [tex]\sigma_{e} \times A \times (80 + 273)^{4} - (25 + 273)^{4} + hA(80 - 25)[/tex]

It is known that for black body emissitivity = 1

Now putting the given values into the above formula as follows.

        kA(T - 80) = [tex]\sigma_{e} \times A \times (80 + 273)^{4} - (25 + 273)^{4} + hA(80 - 25)[/tex]

       [tex]1 \times A(T - 80)[/tex] = A ([tex]\sigma_{e} \times (80 + 273)^{4} - (25 + 273)^{4} + h(80 - 25)[/tex])

              T - 80 = [tex]5.68 \times 10^{-8} \times [(353)^{4} - (298)^{4}] + 1 \times 55[/tex]

               T = [tex]1338.25^{o}C[/tex]

Thus, we can conclude that the inner temperature of the furnace wall is [tex]1338.25^{o}C[/tex].