The proposed design for a blackbody simulator consists of a diffuse gray, circular plate with an emissivity of 0.9 maintained at T_p = 600 K and mounted over a well-insulated hemispherical cavity of radius r_o =100 mm. The opening in the circular plate is r_o/2.

(a) Calculate the radiant power leaving the opening when the surroundings are at 300 K.

(b) Calculate the effective emissivity of the cavity, ?_e, which is defined as the ratio of the radiant power leaving the cavity to the rate at which the heated circular plate would emit radiation if it were black.

(c) Determine the surface temperature of the hemi-spherical cavity, T _{h c.}

(d) The For plate emissivities of ?_p = 0.5, 0.7, and 0.9, plot ?_e and T _hc as a function of the opening in the circular plate over a range from r_o/8 to r_o/2. All other conditions remain the same.

Transcribed Image Text:

T- 300 K Molten metal T- 900 K. E- 055 L = 100 mm D= 250 mm