Figure shows (in cross section) a wall consisting of four layers, with thermal conductivities k1 = 0.060 W/m ? K, k3 = 0.040 Wm ? K, and k4 = 0.12 Wm ? K (k2 is not known). The layer thicknesses are L1 = 1.5 cm, L3 = 2.8 cm, and L4 = 3.5 cm (L2 is not known). The known temperatures are T1 = 30oC, T12 = 25oC, and T4 = ?? 10oC. Energy transfer through the wall is steady. What is interface temperature T34?

Transcribed Image Text:

-T, Tas T12