A 5-mm-thick stainless steel strip (k = 21 W/m•K, rho = 8000 kg/m3, and cp = 570 J/kg•K) is being heat treated as it moves through a furnace at a speed of 1 cm/s. The air temperature in the furnace is maintained at 930°C with a convection heat transfer coefficient of 80 W/m2•K. If the furnace length is 3 m and the stainless steel strip enters it at 20°C, determine the temperature of the strip as it exits the furnace.

The temperature of the strip as it exits the furnace is 819.15 °C

Explanation:

The characteristic length of the strip is given by;

The Biot number is given as;

< 0.1,  thus apply lumped system approximation to determine the constant time for the process;

The time for the heating process is given as;

Apply the lumped system approximation relation to determine the temperature of the strip as it exits the furnace;

Therefore, the temperature of the strip as it exits the furnace is 819.15 °C