A flat plate of polished copper of surface emissivity 0.1 is 0.1 m long and 0.1 m wide. The plate is placed vertically, with one side heated to a surface temperature of 500 K, and the other side remaining insulated. The heated side is exposed to quiescent air at 300 K and the surroundings are also at 300 K. Assume that air can be taken as an ideal gas. Estimate the heat rate from the flat plate.
Answer:
The heat rate is
Explanation:
From the question we are told that
The surface emissivity is [tex]e=0.1[/tex]
The length is [tex]L = 0.1 \ m[/tex]
The width is [tex]W = 0.1 \ m[/tex]
The surface temperature of one side is [tex]T_1 = 500 \ K[/tex]
The temperature of the quiescent air [tex]T_c = 300 \ K[/tex]
The temperature of the surrounding is [tex]T_s = 300 \ K[/tex]
The heat rate from the flat plate is mathematically represented as
[tex]Q = \sigma A e (T_1^4 – T_a^4)[/tex]
Where [tex]\sigma[/tex] is the quiescent air Stefan-Boltzmann constant and it value is
[tex]\sigma = 5.67*10^{-8} m^{-2} \cdot K^{-4}[/tex]
A is the area which is mathematically evaluated as
[tex]A = W * L[/tex]
substituting values
[tex]A = 0.1 * 0.1[/tex]
[tex]A = 0.01 \ m^2[/tex]
substituting values
[tex]Q = 5.67 *10^{-8} * (0.01) *(500^4 -300^4)[/tex]
[tex]Q =3.045 \ Watt[/tex]