Perers, Bengt1; Duff, William S.4; Daosukho, Jirachote4
1 Department of Civil Engineering, Technical University of Denmark2 Section for Building Physics and Services, Department of Civil Engineering, Technical University of Denmark3 Colorado State University4 Colorado State University
A novel geometry ICPC solar collector was developed at the University of Chicago and Colorado State University. A ray tracing model has been designed to investigate the optical performance of both the horizontal and vertical fin versions of this collector. Solar radiation is modeled as discrete uniform rays. Rays falling on the collector are followed as they are attenuated by various components of the collector until they are absorbed by the fin or escape. The extent to which each absorbed ray is attenuated is recorded. Modelled collector properties are transmittance and translation of a ray passing through transparent media, the size of the gap between the glass tube and fin, reflectivity of the reflective surface, absorptivity of the fin and blocking and displacement of the rays by adjacent tubes. . Presentation of the progressive animation of individual rays and associated summary graphics at the various specified incident angles provide model verification for the investigation into causes of ray attenuation and provide accounts for rays that escape. Two fourteen tube modules were tested on Sandia National Laboratory’s two-axis tracking (AZTRAK) platform. By adjusting the tracking of the platform to the desired incident angle of the sun’s rays, performance of the novel ICPC solar collector at various specified angles along the transverse and longitudinal evacuated tube directions were experimentally determined. To validate the ray tracing model, transverse and longitudinal performance predictions at the corresponding specified incident angles are compared to the Sandia results. A 100 m2 336 Novel ICPC evacuated tube solar collector array has been in continuous operation at a demonstration project in Sacramento California since 1998. Data from the initial operation of the array are used to further validate the ray tracing model. Examples of the progressive casting of individual rays across the evacuated tube aperture width and the fit to experimental data are shown in the accompanying figures.