Question

A central receiver in a solar power plant absorbs a concentrated solar flux from heliostats. However, losses from free convection and radiation lowers the collection efficiency. Consider a receiver with a diameter of 7 m and a height of 12 m that has an emissivity of 0.25 and a surface temperature of 1100 K. If the solar flux is 100,000 W/m², find the collection efficiency. The ambient air and surroundings are at a temperature of 300 K. Assume the curvature of cylinder has a negligible effect on boundary layer development and use the Churchill and Chu correlation to determine the Nusselt number.

Answer 1