Stoves and furnaces – Tool having fluid fuel burner – Curling iron
Patent
1991-11-01
1992-10-13
Dority, Carroll B.
Stoves and furnaces
Tool having fluid fuel burner
Curling iron
F24J 218
Patent
active
051541637
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
The present invention relates to a radiation concentrator, particularly for solar power station.
Such radiation concentrators for solar power station are known, essentially constituted by cylindrical reflectors with a parabolic base which concentrate the sun's rays on cylindrical tubes of circular section, disposed at the focus of the parabola and whose generatrices are parallel to those of the reflector, these tubes being passed through by a heat-transfer fluid. These concentrators present the advantage of allowing the production of parabolic reflectors with a large angular aperture which make it possible to dispose the heat-transfer tube near the center of gravity of the reflector, which promotes the mechanical resistance of the assembly of the concentrator and allows the concentrator to pivot about its center of gravity, minimizing the relative displacements of the heat-transfer tube, which simplifies the problems of tightness thereof.
Such concentrators present a relatively weak concentration and this is why it has been proposed to add to the parabolic reflector a so-called "CPC" type reflector, i.e. a reflector constituted by two cylindrical elements of which the elliptic base is symmetrical with respect to a central axis and of which one of the foci is constituted by the downstream end of the reflector element which is symmetrical thereto with respect to the central axis, and the other focus is constituted by the intersection of the straight line joining the downstream end of this element to the upstream end of the other element with the parabolic reflector opposite the tube conveying the heat transfer fluid.
However, in such concentrators, the increase in concentration furnished by the CPC is significantly manifested only for parabolic reflectors of small angular aperture, so that the manufacturers of collectors have preferred, for the reasons mentioned above, to employ cylindrical collectors associated with simple parabolic reflectors despite the relatively low concentration resulting therefrom.
SUMMARY OF THE INVENTION
It is an object of the present invention to overcome these drawbacks by proposing a novel type of association of parabolic reflectors and reflectors of CPC type.
The present invention thus has for an object a concentrator device intended for effecting concentration of substantially parallel radiations on a receiver element, this device being constituted by cylindrical elements symmetrical with respect to a plane P of the same direction as the radiations, characterized in that it comprises, on each side of the plane of symmetry P, at least one concentrator element, each concentrator element comprising a principal cylindrical reflector whose base is constituted by an arc of parabola AA', of which the axis zz' is parallel to the direction of the radiations and is offset by a distance d with respect to the plane of symmetry P on the side of the arc of parabola A,A', and a secondary reflector, constituted by two cylindrical elements B C D, B' C' D', and whose base is constituted by at least one arc of generalized involute BC,B'C' of the outer surface of the receiver element, whose concavities face each other, each of these arcs terminating in an upstream end B,B' determining a segment of straight line BB' on which is positioned the focus F of the arc of parabola AA' constituting the base of the principal reflector, and a downstream end C,C', the focus of each of the arcs of generalized involute BD and B'D' being respectively constituted by the end A',A of the arc of parabola AA' facing its concavity.
The concentrator according to the invention makes it possible notably to improve the concentration in a ratio of about 2.5.
Moreover, the concentrator according to the invention makes it possible to attain large angles of aperture, able to attain 120.degree., without noteworthy loss of concentration.
In fact, it is known that, to obtain an optimum yield of a concentrator, it must be considered that the sun's rays are not all parallel, and that rays deviating b
REFERENCES:
patent: 4327969 (1982-05-01), Giutronich et al.
patent: 4505260 (1985-03-01), Metzger
Winston et al., Applied Optics, vol. 19, No. 3, Feb. 1980, Design of Non-Imaging Concentrators As Second Stages In Tandem With Image-Forming First Stage Concentrators, pp. 347-351.
Kritchman, Applied Optics, vol. 21, No. 5, Mar. 1982, Asymmetric Second Stage Concentrators, pp. 870-873.
Winston et al., N.T.I.S. Technical Notes, No. 10, Part C, Oct. 1984, Two-Stage Off-Axis Cylindrical Solar Concentrator, p. 774.
Bassett et al., Optical and Quantum Electronics, vol. 10, No. 1, Jan. 1978, The Collection of Diffuse Light Onto An Extended Absorber, pp. 61-82.
Mills et al., Solar Energy, vol. 20, No. 1, 1978, Asymmetrical Non-Imaging Cylindrical Solar Concentrators, pp. 45-55.
A.R.M.I.N.E.S.
Dority Carroll B.
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