Let us consider a solar powered water heater. The solar collector surface is coated with black chrome, whose emissivity can be approximated to be 0.9 for radiation at wavelengths less than 5 m and 0.05 for radiation greater than 5 m. How much heat does this surface deliver to the water circulating in the collector when solar radiation is incident on the surface at a rate of 600 W/m2 and the absorber surface temperature is 70C. The air and effective sky temperatures are 25C and 15C, respectively, and the convection heat transfer coeffcient is 10 W/m2 -K. Assume that the temperature of the sun is 5800 K.