determine the view factor, and the net heat transfer by radiation between two gray surfaces, A (εA= 0.88) and B (εB= 0.65) at temperatures 450°C and 50°C, respectively if d. surfaces A and B concentric cylindrical tubes with diameters of 400 mm and 200 mm, respectively e. both surfaces are discs of diameter 3 m one exactly above the other, 1 m apart

determine the view factor, and the net heat transfer by radiation between two gray surfaces, A (εA= 0.88) and B (εB= 0.65) at temperatures 450°C and 50°C, respectively if d. surfaces A and B concentric cylindrical tubes with diameters of 400 mm and 200 mm, respectively e. both surfaces are discs of diameter 3 m one exactly above the other, 1 m apart

Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

Section: Chapter Questions

Problem 1.1MA

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A furnace is located next to a dense array of cryogenic fluid piping. The ice-covered piping approximates a plane surface with an average temperature of Tp = 0°C and a total, hemispherical emissivity of εp = 0.56. That is, the piping can be replaced by a flat surface with the given properties. The furnace wall has a temperature of Tf = 247°C and a total, hemispherical emissivity of εf = 0.86. To minimize the heat loading on the regirgeration equipment and piping, a reflective aluminum radiation shield with a total, hemispherical emissivity of εs = 0.13 on each of its sides is installed between the pipiing and the furnace wall as shown. Assume that all surfaces are diffuse and gray and treat the problem as one-dimensional (surfaces form infinite parallel plates). What is the heat load on on the refrigeration unit? That is, what is the net radiative power at the surface which approximates the dense array of ice-cold piping, qrad,p in Watts?
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Question 30 of 30 く - / 4.3 View Policies Current Attempt in Progress Two concentric spheres of diameter D = 0.8 m and D2 = 1.2 m are separated by an air space and have surface temperatures of T = 410 K and T2 = 300 K. (a) If the surfaces are black, what is the net rate of radiation exchange between the spheres, in W? 912 = W (b) What is the net rate of radiation exchange between the surfaces if they are diffuse and gray with &j = 0.5 and ɛ2 = 0.05, in W? 912 = i W (c) What is the net rate of radiation exchange if D2 is increased to 20 m, with ɛ2 = 0.05, ɛ = 0.5, and D = 0.8 m, in W? 912 = W (d) What is the net rate of radiation exchange if the larger sphere behaves as a black body (ɛ2 = 1.0) and with &j = 0.5, D2 = 20 m, and D = 0.8 m, in W? 912 = i W Physical Properties Mathematical Functions II