A house wall is made up of three layers with the following properties (inside to outside): inner plaster δ 1 = 1.5 cm, λ 1 = 0.87W/K m; wall of perforated bricks δ 2 = 17.5 cm, λ 2 = 0.68W/K m; outer...

A house wall is made up of three layers with the following properties (inside to outside): inner plaster δ₁
= 1.5 cm, λ₁
= 0.87W/K m; wall of perforated bricks δ₂
= 17.5 cm, λ₂
= 0.68W/K m; outer plaster δ₃
= 2.0 cm, λ₃
= 0.87W/K m. The heat transfer coefficients are α₁
= 7.7W/m²K inside and α₂
= 25W/m²K outside. Calculate the heat flux, ˙q, through the wall, from inside at ϑ₁
= 22.0 ◦C to the air outside at ϑ₂
= −12.0 ◦C. What are the temperatures ϑW1 and ϑW2 of the two wall surfaces?