A central receiver in a solar power plant absorbs a concentratedsolar flux from heliostats. However, losses from free convectionand radiation lowers the collection efficiency. Consider a receiverwith a diameter of 7 m and a height of 12 m that has an emissivityof 0.25 and a surface temperature of 800 K. If the solar flux is100,000 W/m2, find the collection efficiency. The ambient air andsurroundings are at a temperature of 300 K. Assume the curvature ofcylinder has a negligible effect on boundary layer development anduse the Churchill and Chu correlation to determine the Nusseltnumber.
