THE STATE-OF-THE-ART IN MODELING LINE-AXIS CONCENTRATING SOLAR-ENERGYCOLLECTORS

To enable accurate predictions of the thermo-physical performance of l ine-axis concentrating solar energy collectors to be made, a unified a pproach that allows detailed consideration of both the thermal and opt ical behaviour in such systems was developed. Employing ray-trace tech niques, the incident energy distributions at the surfaces of the compo nents of line-axis systems are determined, for both diffuse and direct constituents of the incident insolation. To calculate accurately the temperatures and air velocities within the collector, the energy fluxe s determined with the ray trace technique, are incorporated into the b oundary conditions of a in-house developed, finite element model for p redicting the thermo-fluid behaviour in line-axis systems. With the de veloped model a case study is performed for an inverted absorber CPC s ystem. Isothermal plots and velocity vector diagrams illustrate the co nvective heat transfer within the collector cavity. The effect that si mple modifications in system geometry can have on the thermo-physical performance of line-axis systems is highlighted and the efficiency gai ns that can result are discussed.