Determination of optically feasible heliostat field region for solar power tower system employing innovative receiver aperture

The proper prediction of the optical performance of the Solar Power Tower (SPT) system is a critical requirement. In this study, the heliostats are assumed to be negligibly small in dimension compared to the inter-heliostat distance, and the receiver aperture is idealized to be the outer surface of a cone. The receiver aperture is represented using the tilt angle. The interception efficiency of a heliostat could be predicted with the help of the ratio of the receiver aperture slant height to the heliostat characteristic diameter and the tilt angle of the receiver aperture. The cosine and the attenuation efficiency factors have also been estimated, but, the shading and blocking factors have not been considered. The outcome of the numerical analysis showed that the optical performance potential of a field location is strongly dependent on the tilt angle of the receiver aperture. The optimum value of the tilt angle of the receiver aperture was seen to vary with the latitude and the tower height. In general, the optical performance of the heliostat field improved with the increase in the tower height and an increase in the ratio of receiver aperture slant height to heliostat characteristic diameter. But, the results also indicated that the degree of improvement in the optical performance due to a tall tower is a strong function of the latitude. Also, increasing the receiver aperture slant height relative to the heliostat characteristic diameter beyond a certain limit failed to enhance the optical performance by any significant extent.