5.11 WP A flaked cereal is of thickness 2L = 1.2 mm. The density, specific heat, and thermal conductivity of the flake are p= 700 kg/m3, C, = 2400 J/kg

· K, and k = 0.34 W/m K,%3Drespectively. The product is to be baked by increasing its temperature from T; = 20°C to Tf= 220°C in a convection oven,through which the product is carried on a conveyor. If the oven is Lo = 3 m long and the convection heat transfer coefficient at the product surface and oven air temperature are h = 55 W/m2 .K and T = 300°C, respectively, determine the required If the thickness of the coating is L = 1 mm and it has an initial uniform temperature of T; = 200°C, how long will it take for the surface to achieve a safe-to-touch temperature of 42°C if the convection co efficient is h = 250 W/m2 K? What is the corresponding value of the interface temperature? The thermal conductivity and diffusivity of the plastic are k = 0.25 W/m K and a = 1.20 x 10-7m2/s, respectively.