GATE MT 2016 Q34. The lining of a box-type furnace is made up of a refractory layer and steel plate as shown in the figure. Steady state temperature at the surface of the refractory is 1273 K and that at the outer steel surface is 473 K. If the steady-state heat flux through the refractory-steel plate composite is 1600 W.m-2, and heat flow is along x-direction, the thermal contact resistance (W-1.m2.K) between refractory and steel is _____. Given data: Thermal conductivity of refractory = 1.2 W.m-1K-1 Thickness of refractory lining = 80 mm Thermal conductivity of steel = 32 W.m-1K-1 Thickness of steel plate = 4 mm