A novel sun-tracking and target-aiming method to improve the concentration efficiency of solar central receiver systems

The solar central receiver (SCR) system is an important candidate for solar thermal utilization. The cosine loss and astigmatism of heliostats are two major factors which lead to the low concentration efficiency of SCR systems. Most public discussions of concentration efficiency improvement of SCR systems focused on astigmatism correction; however, not so many studies were given to reducing cosine loss of heliostats. In this paper, we proposed a new sun-tracking and target-aiming method for SCR systems in order to eliminate the cosine loss and enhance the concentration efficiency. We calculated the tracking formulae of the sun-tracking strategy and target-aiming strategy by using coordinate rotation transformation method, designed an aspheric lens in target-aiming device by using non-imaging optics principles, and finally constructed the optical model of the proposed system in TracePro software to simulate its concentration performance. The computational results demonstrated the kinematic feasibility of the sun-tracking strategy and target-aiming strategy. The simulation results showed that the proposed method can improve the concentration efficiency of SCR systems obviously in some cases. This novel sun-tracking and target-aiming method sheds light on the field efficiency improvement of SCR systems.