Page 37 - Design of Solar Thermal Power Plants
P. 37

30                        1. INTRODUCTION

            1.2.3.1 Optic Terms
             1. Absorber.
                Element of the receiver absorbing radiant solar energy and
                transferring it to a fluid in the form of heat.
             2. Concentrator aperture area.
                The maximum projected area of solar irradiation intercepted by the
                concentrator, which is actually the sum of all mirror areas in a
                concentrator.
                This is different from the contour area. The concentrator contour
                area contains the clearance between reflective glasses and is
                normally larger than the aperture area.
             3. Solar collector net aperture area.
                The area of the perpendicular projection over the aperture plane of
                the solar collector reflecting/refracting components. In a line
                focusing system it is this surface plus the part of the perpendicular
                projection of the steel receiver tube onto the aperture plane that
                does not overlap, provided that the sun-oriented side of the
                receiver is absorbing radiation. For LFR and heliostat: the net
                aperture area of a Fresnel collector or heliostat is defined as the sum
                of the net collecting areas of its mirror segments. The net aperture
                area of a mirror segment is the perpendicular projection of the
                reflective mirror area over its aperture plane when they are in
                horizontal position.
             4. Solar collector gross aperture area.
                The area of the flat surface defined by the outer perimeter of the
                collector, including the gaps between adjacent reflectors. This
                definition may be used for modules, heliostats, heliostat fields,
                parabolic dishes, LFRs, etc., as well as complete concentrating
                collectors.
             5. Optical concentration ratio.
                Ratio of the average irradiance integrated over the receiver area to
                irradiance incident on the solar collector aperture, also called as
                flux concentration ratio.
             6. Geometric concentration ratio.
                The ratio of the collector aperture area to the receiver aperture area.
             7. Receiver net collection area.
                The maximum receiver flat area that accepts concentrated solar
                radiation. It is given by the sum of the products of the active length
                and diameter of the receiver elements that compose the receiver.
             8. Solar field
                The part of the CSP plant that collects and concentrates beam solar
                radiation. In CSP plants with a parabolic trough collector or Fresnel
                linear collectors, the solar field is composed of a set of solar collectors
                and their piping interconnections and headers. In a central receiver
   32   33   34   35   36   37   38   39   40   41   42