The irradiation (in kW/m2) for the upper plate is

Question

Common Data for Question 01 & 02

Radiative heat transfer is intended between the inner surfaces of two very large isothermal parallel metal plates. While the upper plate (designated as plate 1) is a black surface and is the warmer one being maintained at 727⁰C, the lower plate (plate2) is a diffuse and gray surface with an emissivity of 0.7 and is kept at 227⁰C. Assume that the surfaces are sufficiently large to form a two surface enclosure and steady state condition to exist. Stephen Boltzmannn constant as 5.67 ´ 10^–8 W/m²K⁴.

 

1. The irradiation (in kW/m²) for the upper plate is                                                                                                                       

      (a) 2.5                             (b) 3.6                          (c) 17.0                           (d) 19.5

 

      2.  If plate is also a diffuse gray surface with an emissivity value of 0.8, the net radiant heat exchange (in kW/m²) between plate 1 and plate 2                                                                                                                                             

      (a) 17.0                           (b) 19.5                        (c) 23.0                           (d) 31.7