A radiator may be treated as a black body with a true surface area of 6 m^2. It has a surface temperature of 40ĆĀ°C and is situated in a dark room at 20ĆĀ°C. The surface heat transfer coefficient is 4 W/mK. Calculate the radiated heat transfer (Stefan-Boltzmann constant, ĆĘ = 5.67 x 10^-9 W/m^2K^4).