Consider steady-state heat conduction across the thickness in a plane composite wall (as shown in the figure) exposed to convection conditions on both sides.
Given :hi=20 W/m2K; h∘=50 W/m2K; T∞,i=20∘C, T∞,∘=−2∘Ck1=20 W/mK; k2=50 W/mK;L1=0.30 m and L2=0.15 m
Assuming negligible contact resistance between the wall surfaces, the interface temperature, T(in ∘ C), of the two walls will be