Estimating intercept factor of a parabolic solar trough collector with new supporting structure using off-the-shelf photogrammetric equipment

Abstract

When a new design for a solar collector is developed it is necessary to guarantee that its intercept factor is good enough to produce the expected thermal jump. This factor is directly related with the fidelity of the trough geometry with respect to its theoretical design shape. This paper shows the work carried out to determine the real shape and the intercept factor of a new prototype of parabolic solar collector. Convergent photogrammetry with off-the-shelf equipment was used to obtain a 3D point cloud that is simultaneously oriented in space and adjusted to a parabolic cylinder in order to calculate the deviations from the ideal shape. The normal vectors at each point in the adjusted surface are calculated and used to determine the intercept factor. Deviations between adjusted shape and the theoretical one suggest mounting errors for some mirror facets, resulting in a global intercept factor slightly below the commonly accepted limit for this type of solar collector.