GATE 2016 ME (ME3) – Question 25

Heat Transfer · Modes of heat transfer, one-dimensional conduction, resistance concept · 1 mark · Numerical answer

Steady one-dimensional heat conduction takes place across the faces 1 and 3 of a composite slab consisting of slabs A and B in perfect contact as shown in the figure, where k𝐴, k𝐵 denote the respective thermal conductivities. Using the data as given in the figure, the interface temperature T2 (in °C) is __________

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Correct answer: 67 to 68

Explanation

For unit area, resistances are0.1/20=0.005 and0.3/100=0.003m²K/W. Steady heat flux is(130−30)/0.008=12500W/m². The first-layer drop is12500×0.005=62.5K, so the interface is **67.5°C**. Heat flux is common to both layers.