The net radiative heat transfer (in kW) from the roof to the floor is_____

Question

A hermispherical furnace of 1 m radius has the inner surface (emissivity, e=0.5) is kept at 600K. Stafan-Boltzmannn constant is 5.668´10^–8W/m².K⁴. The net radiative heat transfer (in kW) from the roof to the floor is_______