In Linear Fresnel solar concentration systems there are some energy losses due to the arrangement of the primary reflectors. An important loss of geometric type is caused by the fact that mirrors have only one degree of freedom. Therefore, the accuracy of the solar tracking, at the ends of the collector, cannot be guaranteed, especially if the height of the absorber tube is considerable. The problem could be solved by making the primary reflectors placed at the ends of the plant movable around two axes. In the work, the mathematical law is analytically obtained to determine the position that each reflectors must assume during the day. The study shows that they must be moved independently in each direction. For the purposes of reducing the cost of the plant, a configuration is studied in which, around an axis, the reflectors are moved with the same motor, differentiating the movement only around the other axis of rotation. Thanks to the presence of the secondary reflector, the tracking error committed is not significant.
Finally, the advantages, in terms of performance, obtained with the adoption of the above-mentioned reflectors, both for North-South oriented plants and for East-West oriented plants, are illustrated.
concentrating solar power, linear Fresnel, bi-axial tracking system, law of motion
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