A gray surface has a directional total absorptivity given by a(0) = 0.8 cos40. This flat surface is exposed to normally incident sunlight of flux 1250 W/m. A fluid flows past the back of the thin radiation absorber plate at T, = 320 K and with a velocity that gives a heat transfer coefficient of h = 60 W/mK. The ambient air temperature, T.-,-300K. Neglecting natural convection from the exposed to air surface, but considering the respective radiation loss what is the equilibrium temperature of this flat plate radiation collector?