Question

A house has a composite wall of wood (exterior) (k = 0.12 W m-1 K -1 , 20 mm thick), fibreglass insulation (k = 0.045 W m-1 K -1 , 70 mm thick) and plasterboard (interior) (k = 0.25 W m-1 K -1 , 10 mm thick). Determine the total heat loss through the wall when the inside temperature is 20 °C, the outside temperature is -10 °C, the inside heat transfer coefficient is 15 W m-2 K -1 , and the outside heat transfer coefficient is 65 W m2 K -1 . Also, determine the temperature at the interface between the plasterboard and the insulation, assuming contact resistance is negligible.

Answer #1

A carpenter builds an exterior house wall with a layer of wood
2.8 cm thick on the outside and a layer of Styrofoam insulation 2.3
cm thick on the inside wall surface. The wood has k=0.080W/(m⋅K),
and the Styrofoam has k= 0.010 W/(m⋅K). The interior surface
temperature is 19.0 ∘C , and the exterior surface temperature is
-11.0 ∘C .
Part A
What is the temperature at the plane where the wood meets the
Styrofoam?
Part B
What is the...

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