Chapter 4, Problem 4.26P

A cubical glass melting furnace has exterior dimensions of width $W=5\text{m}$ on a side and is constructed from refractory brick of thickness $L=0.35\text{m}$ and thermal conductivity $k=1.4\text{W/m}\cdot \text{K}\text{.}$ The sides and top of the furnace are exposed to ambient air at 25°C, with free convection characterized by an average coefficient of $h=5{\text{W/m}}^{\text{2}}\cdot \text{K}\text{.}$ The bottom of the furnace rests on a framed platform for which much of the surface is exposed to the ambient air, and a convection coefficient of $h=5{\text{W/m}}^{\text{2}}\cdot \text{K}$ may be assumed as a first approximation. Under operating conditions for which combustion gases maintain the inner surfaces of the furnace at 1100°C, what is the heat loss from the furnace?