Question
Home work help needed will rate high double points
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Consider two coaxial cylinders of radii r1 = 5 cm and r2 = 15 cm which are maintained at T1 = 1000 K and T2 = 300 K, respectively. The emissivity for the surfaces arc epsilon1 = 0.6 and epsilon2 = 0.9, respectively. Calculate the radiation exchange between the cylinders per meter length of the cylinder. A radiation shield of radius r3 = 10 cm having an emissivity epsilon3 = 0.1 is placed coaxially between the two cylinders. Sketch the radiation network. Calculate the heat transfer rate between cylinders 1 and 2 with the shield present, and determine the equilibrium temperature T3 of the shield. Radiosity matrix method
Explanation / Answer
radiation exchange heat = A1 * sigma (t1^4 - t2 ^ 4) / (1/e1 + (1-e2)/e2 * r1/r2^2) =pi * 5*10^-2 *5.67*10^-8 *( 1000^4 -300^4) /( 1/0.6 + 0.1/0.9 * 5/15^2)= 5262.359J