A 2 m long cylindrical rod (radius r = 75 mm) is coated by an insulation layer (thickness: 2 mm).The rod is uniformly, heated by an electrical current. The air flows around the coated rod at 300 Kand 4 m/s. Ignore radiation and the heat transfer at two ends of the rod.(a) What is the convection heat transfer coefficient h between the air and the coating outersurface?(b) Calculate the Biot number of the rod.(c) The electrical current is suddenly cut off (no heat generation any more). How long does ittake for the rod temperature to drop from 1000 K to 600 K?Properties of the air: pa = 0.7 kg/m³, Cp,a= 1030 J/kg K, a = 38.8×106 m²/s, ka = 0.041 W/mK,da 56.7×106 m²/s, and Pra = 0.684..=Properties of the rod: pr = 7832 kg/m³, Cpr = 559 J/kg K, and ky = 48.8 W/m.K.Properties of the coating: ke = 0.4 W/m.K.

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Elements Of Electromagnetics

7th Edition

ISBN:9780190698614

Author:Sadiku, Matthew N. O.

Publisher:Sadiku, Matthew N. O.

ChapterMA: Math Assessment

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