The external brick wall of a building has a surface area A of 830 m² and thickness 8 of 300 mm. The wall has a thermal insulation on its outer sur- face. The thermal conductivity of concrete k is 1.6 W/m K and of insulation k; is 0.04 W/m K. The indoor and outdoor air temperatures are t₁ = 21°C and to = 3°C, respectively. The heat-transfer coefficients are h₁ = 14 W/m²K (on the inner surface) and h, = 20 W/m²K (on the outer surface). Determine (1) the rate of heat loss through the wall without insulation and (2) the thick- ness of the insulation required to reduce the rate of heat loss by 60%.

The external brick wall of a building has a surface area A of 830 m² and thickness 8 of 300 mm. The wall has a thermal insulation on its outer sur- face. The thermal conductivity of concrete k is 1.6 W/m K and of insulation k; is 0.04 W/m K. The indoor and outdoor air temperatures are t₁ = 21°C and to = 3°C, respectively. The heat-transfer coefficients are h₁ = 14 W/m²K (on the inner surface) and h, = 20 W/m²K (on the outer surface). Determine (1) the rate of heat loss through the wall without insulation and (2) the thick- ness of the insulation required to reduce the rate of heat loss by 60%.

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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