Metal plates (k = 180 W/m K, = 2800 kg/m 3 , and c p

Metal plates (k = 180 W/m · K, ρ = 2800 kg/m³, and c_p = 880 J/kg · K) with a length of 1 m and a thickness of 2 cm exiting an oven are then conveyed through a 10-m-long cooling chamber at a speed of 5 mm/s. The plates enter the cooling chamber at an initial temperature of 155°C. In the cooling chamber, the plates are cooled with 10°C air blowing in parallel over them. To prevent any incident of thermal burn, it is necessary to design the cooling process such that the plates exit the cooling chamber at a relatively safe temperature. Determine the air velocity such that the temperature of the plates exiting the cooling chamber is 45°C or less. Assume combined laminar and turbulent flow (verify this assumption).

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2 cm Cooling chamber Metal plate 5 mm/s Blowing air, 10°C f f