In: Mechanical Engineering
A thick steel slab (ρ= 7800 kg/m3, c= 480 J/kg·K, k=
50 W/m·K) is initially at 300°C and is cooled by water jets
impinging on one of its surfaces. The temperature of the water is
25°C, and the jets maintain an extremely large, approximately
uniform convection coefficient at the surface. Assuming that the
surface is maintained at the temperature of the water throughout
the cooling, how long will it take for the temperature to reach
50°C at a distance of 28 mm from the surface?