4.0 cm
Hope this helps (:
q = 1156363.6W/m².
To calculate the heat flux per unit area (W/m²) of a sheet made of metal:
q = -k(ΔT/Δx)
q = -k[(T₂ - T₁)/Δx]
Where, k is the thermal conductivity of the metal, ΔT is the temperature difference and Δx is the thick.
With Δx = 11 mm = 11x10⁻³m, T₂ = 350°C and T₁ = 110°C, and k = 53.0 W/m-K:
q = -53.0W/m-K[(110°C - 350°C)/11x10⁻³m
q = 1156363.6W/m²
