Parametric cylindrical solar collector having an optimised secondary reconcentrator and method for designing same

Design process of a parametric cylindrical solar collector such as the one described in the above claims which comprises the following stages:

• With φ being the half angle of acceptance of the radiation impacting the primary reflector (1) first the curve of the geometric location is drawn for the points from which it is possible to emit light confined in an opening angle θ equal to 2φ so that the end rays of the aforementioned light beam (4) are tangent to the absorber tube (6), one of them without any reflection over the secondary reconcentrator (5) and the other after a single reflection over the aforementioned reconcentrator (5);
• the end point (11) of this curve, the complete geometry of the secondary reconcentrator (5), mirrored (10) and the relative position between the absorber tube (6) and glass tube (6′), are obtained imposing the condition of symmetry and forcing that, for the point in question (11), all of the intermediate rays (4) placed between the aforementioned end rays reach the absorber tube (6) after one or no reflections in the secondary reconcentrator (5).
• Secondly, the curve which, passing through the point (11), ensures that the impacting rays perpendicular to the wave front inclined to an angle φ with respect to the horizontal in a clockwise direction are reflected tangent to the absorber tube (6), is drawn;
• both of the previous curves intersect at points (11) and (11′) and define the limits of the curve of the primary reflector's right parametric section (9);
• the left parametric section of the primary reflector is symmetric to the latter.
• The second section of the primary reflector's geometry is a parabolic section (8);
• both end points (12) of the parabolic section (8) meet three conditions:
• they are symmetrical, they see the tube (6) with an acceptance equal to or higher than that of the design and they do not block the light beam reflected by point (11′) and its symmetrical one. In these two points (12) both discontinuities in the geometry of the primary are manifested.