Q1) A 6 m wide 2.8 m high wall is constructed of one layer of common brick (k = 0. 72 W/m. °C) of thickness 20 cm, one inside layer of light-weight plaster (k = 0.36 W/m. °C) of thickness 1 cm, and one outside layer of cement based covering (k = 1.4 W/m. K) of thickness 2 cm. The inner surface of the wall is maintained at 23 °C while the outer surface is exposed to outdoors at 8 °C with a combined convection and radiation heat transfer coefficient of 17 W/m².°C. It is desired to insulate the wall in order to decrease the heat loss by 75 %. For the same inner surface temperature, determine the thickness of insulation and the outer surface temperature if the wall is insulated with polyurethane foam (k = 0.025 W/m. °C). Use thermal resistance network.

Q1) A 6 m wide 2.8 m high wall is constructed of one layer of common brick (k = 0. 72 W/m. °C) of thickness 20 cm, one inside layer of light-weight plaster (k = 0.36 W/m. °C) of thickness 1 cm, and one outside layer of cement based covering (k = 1.4 W/m. K) of thickness 2 cm. The inner surface of the wall is maintained at 23 °C while the outer surface is exposed to outdoors at 8 °C with a combined convection and radiation heat transfer coefficient of 17 W/m².°C. It is desired to insulate the wall in order to decrease the heat loss by 75 %. For the same inner surface temperature, determine the thickness of insulation and the outer surface temperature if the wall is insulated with polyurethane foam (k = 0.025 W/m. °C). Use thermal resistance network.

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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Question

Q1) A 6 m wide 2.8 m high wall is constructed of one layer of common brick (k =
0. 72 W/m. °C) of thickness 20 cm, one inside layer of light-weight plaster (k =
0.36 W/m. °C) of thickness 1 cm, and one outside layer of cement based covering (k =
1.4 W/m. K) of thickness 2 cm. The inner surface of the wall is maintained at 23 °C while the
outer surface is exposed to outdoors at 8 °C with a combined convection and radiation heat
transfer coefficient of 17 W/m2.°C. It is desired to insulate the wall in order to decrease the
heat loss by 75 %. For the same inner surface temperature, determine the thickness of
insulation and the outer surface temperature if the wall is insulated with polyurethane foam
(k = 0.025 W/m.°C). Use thermal resistance network.

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