(b) The inner and outer surfaces of a 25-cm-thick wall are at 27 C and 45 C, respectively. The outer surface of the wall exchanges heat by radiation with surrounding surfaces at 40 C and convection with ambient air at 42 C, with convection heat transfer coefficient of 9.0 W/m? K. Solar radiation incident on the surface is at a rate of 150 W/m?. If the emissivity and the solar absorptivity of the outer surface are 0.75 and 0.85, respectively: write the expression of the energy balance at the outer surface; (i) (ii) write the expression of conduction heat flux; (iii) calculate the convection heat flux; (iv) calculate the radiation heat flux; (v) calculate the effective thermal conductivity of the wall.

(b) The inner and outer surfaces of a 25-cm-thick wall are at 27 C and 45 C, respectively. The outer surface of the wall exchanges heat by radiation with surrounding surfaces at 40 C and convection with ambient air at 42 C, with convection heat transfer coefficient of 9.0 W/m? K. Solar radiation incident on the surface is at a rate of 150 W/m?. If the emissivity and the solar absorptivity of the outer surface are 0.75 and 0.85, respectively: write the expression of the energy balance at the outer surface; (i) (ii) write the expression of conduction heat flux; (iii) calculate the convection heat flux; (iv) calculate the radiation heat flux; (v) calculate the effective thermal conductivity of the wall.

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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