A furnace door, 1.5m high and 1m wide is insulated from inside and has an outer surface temperature of $70^0C$. If the surrounding ambient air is at $30_0C$. Calculate steady state heat loss from the door. The properties at film temperature $50^0C$ are $\rho= 1.093kg/m^3, C_p = 1.005kJ/kg-K, v = 17.95 × 10^{-6}m^2/s, k = 0.02826W/m-K, Pr= 0.698$. Use the relation $Nu= 0.13(Ra)^{1/3}$.

Given,

$A=1.5×1=1.5m^2 \ (Surface \ Area \ of \ furnace \ door) \\ ts=70℃=343K \ (Door \ surface \ temperature) \\ tb=30℃=303K \ (Surrounding \ temperature) \\ tf=50℃=323K \ (Mean \ film \ temperature) \\ ρ=1.093kg/m^3 \ (Density \ of \ air) \\ Cp=1.005kJ/kgK \ (Specific \ heat \ of …