Hourly and Monthly Variation in Shading and Blocking of Aperture Area in a Linear Fresnel Reflector Field

Abstract

In a Linear Fresnel Reflector (LFR) field, rows of reflectors direct the incident sun rays towards a linear receiver. Some portion of reflector aperture area gets shaded and blocked by neighboring reflector-rows. Thus, complete utilization of reflector aperture area is hampered. Continuously changing sun's position in sky demands appropriate tracking of reflectors, which leads to varying shaded and blocked aperture areas over a day. Orientation of the field also plays an important role. Orientation is defined by the tracking axis of the reflector. For example, North-South (N-S) oriented LFR field is the one having tracking axis of reflector along N-S. In the present work, analytical expressions are used to find out shaded and blocked aperture areas. Results for hourly and monthly variation in shaded and blocked aperture areas for different orientations of the field, different values of spacing between reflector-rows and height of receiver are plotted and compared.