A long iron rod (ρ = 7870 kg/m³, c_p= 447 J/kg·K, k = 80.2 W/m·K, and α = 23.1 × 10^€“6m²/s) with diameter of 25 mm is initially heated to a uniform temperature of 700°C. The iron rod is then quenched in a large water bath that is maintained at constant temperature of 50°C and convection heat transfer coefficient of 128 W/m²·K. Determine the time required for the iron rod surface temperature to cool to 200°C. Solve this problem using analytical one-term approximation method (not the Heisler charts).

Transcribed Image Text:

Iron rod Water, 50°C h = 128 W/m2K