ES2346629B2 - SOLAR RADIATION CONCENTRATOR, WITH MULTIPLE INDEPENDENT PARABOLIC MIRRORS. - Google Patents

Abstract

Solar radiation concentrator, with mirrors Multiple independent parabolic.

Device composed of several mirrors longitudinal (7) of parallel axes, and in turn parallel to the axis length of the receiver (1) on which they focus, whose sections straight lines are parabolic arcs defined for a solar position of reference, passing the parabola (44) through the center point of the mirror (25), and focusing on the center point (3) of the active face (2) of the receiver (1), where the reflected radiation affects, being bounded the width of each mirror to limit the derives from rays reflected in other solar positions than those of reference, and being established the separation between successive mirrors to avoid shadows from a certain height of the Sun.

Description

Solar radiation concentrator, with mirrors Multiple independent parabolic.

Technical sector

The invention falls within the field of solar power plants that require concentration of the original radiation, which in this case is reflected by a series of longitudinal mirrors whose longest axes are horizontal or slightly inclined, and transverse orientable by turning around its axis of longitudinal symmetry; focusing the radiation reflected on a similarly longitudinal receiver, with its long horizontal axis or slightly inclined, and with some inclination transversely, and parallel to the axes of the mirrors.

Said receiver may have very structuring diverse and be composed of very different materials, because it can engage in high temperature thermal uses, to conversion photovoltaic, photochemical or thermochemical processes, or any phenomenon that needs visible type electromagnetic radiation, infrared or ultraviolet. In any case, the receiver will have a surface or active face, which is really relevant to effects of this invention, and is the area in which it affects and is absorbs concentrated radiation.

The invention falls within the so-called field solar, which is the set of mirrors with their frames and elements corresponding focus, to reflect solar radiation directly from the sun on said active face, accumulating on it an intensity much higher than solar radiation original, by affecting the active surface unit of the receiver radiation from several reflective surfaces, which total a surface several times larger than said surface unit.

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Background of the invention

The invention has an immediate background, which It is patent application P201000644, which deals with a Device solar radiation concentrator, with longitudinal mirrors, rotating around its longest axis, these axes being parallel each other and parallel in turn to the active face of the receiver in its longitudinal direction The inventors of this request are the same who sign this. The fundamental difference between the two lies in the profile of the straight section used in the mirrors Longitudinal that make up the solar field. In the cited application, the straight section of the mirrors corresponds to circular arcs, which they do not produce a perfect concentration of rays parallel to their axis of symmetry, but provide an acceptable concentration when the angular aperture with which the mirror illuminates from the center point of the active face of the receiver is sufficiently small so that its value, in radians, matches the sine of the angle, at least in the first three decimal places. In the present invention a perfect concentration of the rays is sought parallel to the axis of symmetry of each set mirror-receiver, which is achieved with profiles parabolic in the straight sections of the mirrors. Now at have only its longest, or longitudinal, axis of rotation, the mirrors only concentrate the sun's rays perfectly in a position of the sun in the celestial vault; and the invention serves to give the precise constructive prescriptions so that the concentration of radiation on the receiver is as high as possible, with the restrictions that may be imposed on the width of the mirrors.

The macroscopic arrangement of the installation is identical in this case to that described in the aforementioned application above, corresponding to the assembly called Fresnel de reflection. In the aforementioned application, several others are analyzed background of this type of assembly, which are simply reviewed here, they were valued in that application. As patents Classics include WO 99/42765, BE 1 013 565 A3 and BE 1 013 566 A3; and as more recent patents WO 2009/029277 A2 and 2009/023063 A2; and other notable patents are WO 2006/000834 A1, WO 02/12799 A2, WO 02/12799 A2 and EP 2 161 516 A1.

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Technical problem to solve

All this background, except the specific the P201000644, ignore the fundamental physical fact that the solar radiation is not perfectly collimated, but comes from solar disk, which has an optical aperture from Earth that is worth 32 '(32 sexagesimal minutes), its intensity being practically uniform throughout the disk, as corresponds to radiation emitted from perfectly diffused form from a spherical surface. This opening means that the incident radiation at a point in the Earth's surface is not simply composed of lightning coming from the sun, but it is a cone of rays whose conical angle It is worth precisely the 32 'mentioned above. Therefore, and in function of the principle of reflection of light, from the point in question no a single ray is reflected, but a set of rays, or beam, of opening exactly equal to that of the incident beam, that is, 32 '. This opening equals 0.0093 radians (or 1/107 radians), which means that when the beam travels distances progressively long, the surface of its cross-sectional section becomes each getting bigger, which produces a low intensity in the receiver solar radiation absorber.

That low value of the radiation received prevents that the heating fluid, which circulates through the absorber tubes, reach high temperatures. Or in the photovoltaic case, it prevents the necessary radiation reaches high performance cells, which They can only be manufactured in small quantities because they are very expensive, but that provide good performance when illuminated with a intensity tens of times greater than natural.

With the current concentration systems denominated Fresnel longitudinal reflection, which are of construction much cheaper than the other systems of concentration, it is impossible to achieve high values of radiation concentration Therefore, the problem to be solved is reach said concentration values sufficiently high in a device of this basic geometry, dimensioning its elements constitutive in a novel way, taking into account the opening natural sunlight and drift, or displacement of the trajectory, of the rays reflected by a mirror, when it rotate to focus on the sun in any position not matching the reference, which is used to define its geometry.

Other prior considerations

In the application presented here, the invention part of a set of slightly concave mirrors in the direction transversal, parallel to each other, geometry markedly longitudinal, that is, with a length much greater than its width. The mirrors have only a degree of freedom of rotation, and specifically its axis of rotation coincides with its axis of symmetry longitudinal, which in turn is the axis that takes support in some standard cylindrical bearings, which sit on the pillars that, every certain stretch of length, are embedded in the ground and rigidly support said bearings, whereby the shaft of clamping, which is also the axis of rotation, always remains fixed on that straight line position, although it can rotate on its imaginary axis central. To do this, at one end of the physical axis it goes in solidarity together with a cogwheel, an auger or a rotating pulley, that by means of an electric motor or a hydraulic pusher, either acting through a direct gear, either through chain or Transmission belt, forces the mirror to rotate on its axis longitudinal center, taking this the corresponding inclination so that its reflected rays are focused on the active surface of the longitudinal receptor. The invention includes specific aspects. novel about the profile of straight section of each mirror, according to its position relative to the receiver.

Solar astronomical tables allow to know at every moment the situation of the sun, for which it is possible to determine with total precision, within the natural solar tolerances, what should be the inclination of each mirror so that its rays reflected impact on the receiver, whose longitudinal axis is parallel to the set of axes of the mirrors. It's important to remember that the maximum angular height at which the sun rises above the local horizon, passing through the meridian at the solstice of summer, is the sum of the complementary angle to the latitude of the place, plus 23º 27 '(degrees and sexagesimal minutes) being the latter value the inclination of the ecliptic axis, and being the smallest angular height the difference between both quantities, in the solstice of winter.

For astronomical reasons, this set geometric concentration of solar radiation presents two different basic assemblies: one according to the meridian, in which the Longitudinal axes of the mirrors and receiver go in the direction North South; and another according to the local parallel, in the which the longitudinal axes of the mirrors and the receiver go in East-West direction; being possible others assemblies, going the longitudinal axes in any direction in the local horizontal plane.

In order to conveniently explain the invention, a brief presentation on the reflection of the radiation. First, when this occurs, a angle between the incident ray and the reflected ray, in such a way that the bisector of said angle coincides with the normal line at plane tangent to the reflective surface at the point of incidence. Like this surface, for each of the mirrors used in the invention, has the same straight section throughout the entire mirror, what is to be determined are the characteristics to be have that straight section for each mirror. In this regard we must remember that solar radiation has a three-dimensional character, and however the definition of a straight section is just two-dimensional For this, solar radiation is projected in what we call optical plane or work plane; what is a plane perpendicular to the longitudinal axes, and therefore short transversely and perpendicularly to the receiver and mirrors. Saying Cut can be set at any point on the length of the axes. In any of the assemblies, the layout can be so long however you want, but transversely you must comply with the specifications set forth in the invention.

It is important to note that these prescriptions they are established in the work plane defined above; and in such sense should be borne in mind that in the assemblies according to the meridian, the projection of the diurnal orbit on that plane is in general an ellipse that has its peak in the local meridian; Y whatever the angular height it presents on the horizon local, the sun always passes through the zenith, and therefore, and for reasons of morning-afternoon symmetry, the reference position it is precisely that, with the projection of the sun on the vertical of the place. Certainly the inclination of the sun's radiation on the local horizon will vary seasonally, as recalled, and this advises prolonging the mirrors, but does not produce any effect in the prescriptions of how the mirror profile should be transversely.

In assemblies according to the parallel, the orbit Daytime sun varies between seasons. Referring to the hemisphere North, which by default will be to which everything is referred, in winter the sun rises well below the heading of 90º, which is the East, it it rises little in the southern part of the celestial vault, and goes south of heading 270º, which is the West. The projection of this orbit in the work plane is a trace, practically straight, that goes up with little slope from its ortho, south of the location that has, pointing further south, and taller, staying high angular already explained, of the difference of the complement of the Latitude and inclination of the ecliptic axis. Conversely, in summer it leaves north of the east cardinal point, and ascends (with faster the lower the latitude) to its maximum height, which in the northern hemisphere is the sum of the complement of the latitude and inclination of the ecliptic axis, in the solstice of summer. Regarding the location of the installation, that orbit is project as a trace that rises from the real ortho of the sun, is, in terms of projection on the work plane, in the vertical of the place when it rises above the East, and continues to ascend until its maximum angular height of that day, which means, in the projection on the work plane, that the rays have less impact inclined than when the sun was on the east. Is important to note that these data refer to the projection on The work plane. If the actual inclination is measured, with all its components, the maximum value is when passing through the meridian local. When passing through the East, although its projection is 90º, the real inclination is around 25º (in latitudes Spanish, at the beginning of summer).

In the parabolic mirrors, all the rays that they propagate in the optical plane parallel to the axis of symmetry of the parable, they will converge in the focus of this one after the reflection in the parable. Parables are usually expressed in a system of coordinates whose apex originates, and as an ordinate axis, Symmetry The abscissa is normal to the ordinate, in said origin. The general equation is

100

where the "a" parameter of proportionality between the square of the abscissa and the ordinate, it has a value that is exactly equal to a quarter of the inverse of the focal length, this being the distance from the apex to focus. So, if to a mirror of the employees in this invention is given a parabolic profile, such that its focal length equals that between the midpoint of the mirror and the midpoint of the receiver, all the rays that go parallel to the axis of symmetry, converge at the midpoint of the receiver. That is not the case of rays not parallel to the axis of symmetry, which is one of the main causes of loss of performance in Fresnel assemblies of reflection, and what motivates this invention, which aims to remedy that weakness in so much that device solar.

The fundamental problem is that only to a solar position on the work plane, given the locations fixed receiver and center mirror, you can take advantage of the above property of radiation concentration on a focus. For the rest of the solar positions projected in the work plane in your daily career, which are a majority, that property is not given. The invention precisely addresses this actually, and provides a device configuration of this type that achieves high concentrations on the receptor, starting of a field of longitudinal mirrors like the classics of Fresnel reflections assemblies, but with unique specifications novel.

Explanation of the invention.

The invention consists in configuring the high concentration solar device with the following elements, optically connected to each other by the trajectories of solar radiation:

-

a solar radiation receiver, longitudinally, supported on high by pillars or structural porches, generally braced transversely, with a height above ground according to the reflection of the radiation reflected by the mirrors, and consisting of an active surface or face that is where the radiation affects concentrated, having said active face transversely certain inclination on the ground, and being also constituted the receiver for some elements that will depend on the ultimate goal of the central in question, which can be the photovoltaic generation, the activation of photochemical processes, or the heating of a fluid thermal to reach high temperatures;

-

a set of longitudinal mirrors, the longitudinal axis of symmetry of each mirror parallel to the longitudinal axis of the receiver, the specular surface being seated in a composite structure by a longitudinal rigid axis that coincides with the axis of symmetry longitudinal of the specular surface, and serves as support fundamental of this one, also counting on small rigid crossbars in solidarity with said material axis, which is rotary, so it rotates the specular surface, the rotation materializing by the action of any gear mechanism or transmission belt that located at one end of the shaft or in an intermediate position of its length, which can be activated either by electric motor or by hydraulic drive; and the material axis being supported on the inside of cylindrical bearings, whose outer part is fixed and it is integral to the pillars or right feet of the mirror support and their structure, which are embedded in the corresponding foundations in the field, the whole existing bearing-pillar every certain distance, coinciding that arrangement with a small interruption of the specular surface, if one chooses because it rotates like this the entire circumference, which is unnecessary for the radiation approach, but it can be of interest for cleaning reasons and to reduce the dynamic load of the wind against the mirror; or keeping the specular surface continue, above the support structure, if you do not opt for the full circumference rotation;

-

being the concave surface mirrors towards its reflective side, said concavity materializing, for each mirror, with the profile of the parable that passes through the center of the mirror and focuses the central point of the active face of the receiver, being its axis of symmetry parallel to the rays of direct sunlight reference, selecting for this purpose a certain position of the sun in its projection in the optical or working plane, called the position of reference.

The invention can materialize preferably in two geographical configurations: according to local meridian, or North-South, and according to the parallel local, or East-West. In the case of the meridian, there are a field of mirrors on each side of the receiver, by symmetry of daytime solar motion, and instead of a single receiver central, there may be two, in dual or double mounting, with the faces active looking at each of the fields, respectively.

For the explanation and application of the invention, an optical or work plane is used, which is a plane perpendicular to the longitudinal axes, and therefore short transversely and perpendicularly to the receiver and mirrors. Saying cut can be set at any point the length of the axes

The corresponding work plane is used to specify in it the transverse inclination of the mirror, whose axis of Longitudinal symmetry will cut the aforementioned plane at a point, which designates as the center of the mirror in question.

In this work plane angles are defined that they form some lines (usually associated with rays and visuals of point to point) with the abscissa axis, and these angles are measured according to the usual pattern of flat trigonometry, turning in direction counterclockwise or levógiro from the positive axis of abscissa. This applies when the general coordinate system of a field of mirrors, whose axis of ordinates is the vertical straight line that passes by the center point of the active surface of the receiver of that field, and as an axis of abscissa perpendicular to the previous one that passes by the center point of the mirror closest to the receiver.

This trigonometric criterion also applies. when it comes to the local coordinate system, associated with each mirror, being in that case the axis of ordinates the normal line to mirror in its central point, and its axis of abscissa perpendicular to anterior axis in the center of the mirror, which is the origin of coordinates

With the reference position of the sun that more forward is defined, projected on the work plane from its position in the celestial vault, the complete parable is determined that passes through the center of the mirror, which is its center of rotation in said work plane, and whose focus is the central point of the face Active receiver. The mirror in question is the arch of that parable contained in a circle of radius E / 2, centered in the center of rotation of the mirror, E being what is called the effective width of the mirror; which is determined in such a way that the drift, or lateral displacement of the rays reflected from the ends of the mirror, does not exceed a fraction P, less than 1, of the apparent width W of the active face of the receiver seen from the mirror, which is equal to the actual width of its active face, R, which is where the radiation affects, multiplied by the cosine of angle formed by the visual to the center point of the active face of the receiver from the center point of the mirror, and the normal line to the active face of the receiver at its center point.

In turn, R is set by the property already mentioned of having the original solar radiation an opening of 1/107 radians The width of the active face of the receiver, R, is fixed at 1/107 of the length that results from dividing the distance from the center of the mirror furthest from the receiver, to the center of the active face of the latter, by the cosine of the angle formed by the visual to the center point of the active face of the receiver from the center point of said mirror, and the normal line to the active face of the receiver at its central point.

The invention contains a complete set of prescriptions to uniquely determine the characteristics geometric elements of the device, depending on the optical relationships established between them, and specifically refer to the height at which the receiver is located, to the width of his active face and his inclination; as well as to the position of successive mirrors across the solar field, the width of these and, above all, the profile of its straight section. further the prescription of focus is given to the sun of each mirror in each moment.

The sun's reference situation for determine the parabolic profile of the mirrors has to be astronomically representative, that is, it must represent a situation in which solar energy has a relevant value and is in turn average of the relevant situations, because that is when the parable is perfectly focused on the center point of the receiver.

The situation or reference position is defined by the inclination with which the sun's rays strike the horizontal, always expressed in the work plane. This inclination, in the methodology to determine the profiles parabolic mirrors, is measured by the angle formed by the solar rays of the reference position with the vertical axis, which It is the ordinate of the device coordinate system. Alternatively it is measured by the angle of position of the rays solar in relation to the abscissa axis of the reference system associated to the work plane, counted in a levógiro sense from the positive semi-axis of abscissa. For device mounts according to the meridian, a value of 90º is applied (º = degrees sexagesimal) at this angle of reference position, as the movement of the sun is always symmetrical in this plane in its daytime movement, and the sun is in the middle of its path in its apparent zenith. With respect to the vertical axis, the angle is therefore null, 0º.

For assemblies according to the parallel, in the Northern hemisphere, with the field mirrors south of the receiver, the angle taken as reference position corresponds to the semi-sum of 90º plus the maximum solar height angle, which is the sum of the complementary latitude of the place plus 23º 27 '; what equivalent to the angle of the reference sunrays, with respect to the vertical axis, be the complement of said semisuma

For assemblies according to the parallel, in the Northern hemisphere, with the field mirrors north of the receiver, the angle of situation that is taken as a reference has as value the semi-sum of 90º sexagesimal plus the supplementary angle of maximum solar height, the latter being the sum of the angle complementary to the latitude of the place plus 23º 27 '; What equals to that the angle of the reference sunrays, with respect to the axis vertical, be negative, and corresponds to the value 90º minus the semi-sum above, having the solar rays of reference pending negative in the installation coordinate system; giving the symmetrical situation in the assemblies according to the parallel in the southern hemisphere.

A capital specification is the height at which the receiver is placed, and its inclination with respect to the horizontal, which depends on the distance to the mirror farthest from the field in question. For reasons of having a good transparency for cross the receiver cover, you should do reflected near the perpendicular on the active face of the receiver. This leads to placing the receiver at a certain height, giving for it indirect prescriptions, because the inclination of the active face of the receiver is defined because it must be normal to the bisector of the field from the center point of the active face of the receiver, said bisector being that of the angle formed with the straight from the central point of the active face of the receiver to the center point of the mirror closest to the receiver, and to the point center of the furthest mirror. As additional prescription indicated that the value of the acute angle that forms the straight line with the horizontal that joins the center point of the furthest mirror in the field with the center point of the active surface of the receiver, is selected in a margin of values between 10º and 80º, with a reference value of 45º.

To determine the spacing between mirrors consecutive, almost complete contiguity is chosen between mirrors consecutive, in order to obtain a concentration factor truly tall. This causes shadows and interference between mirrors, but ensures that the entire surface available for reflect solar radiation on the receiver, within the limits that are imposed on the field of mirrors, is effectively used. The almost complete contiguity means that it is not left between mirrors consecutive more space than that of the mounting tolerances, which are encrypted at a value selected between 0.1% and 5% of the width of the mirrors. For cleaning or repair of these, it placed with an angle of rotation that takes them to the vertical, or close to it, which can allow access by staff or a robot cleaning.

The length of the mirrors must be at least the length of the receiver, but it is recommended a length somewhat greater, with a length added by the side from which it is going to receive solar radiation in the hours of efficient heat stroke, which it is the south, in the northern hemisphere, for assemblies according to the meridian, the mirrors can be shortened equally north side, and vice versa in the southern hemisphere. For assemblies according to the parallel, or east-west orientation, the mirrors should be longer on both sides, with respect to the receiver length In both assemblies the added length is equal to the height of the midpoint of the active face of the receiver, divided by the tangent of an angle formed by solar radiation and the horizontal or abscissa axis, selected in the design between 20 degrees and 90 degrees sexagesimal.

In a solar power plant there can be a plurality of these receiver-mirror sets, which will be parallel to each other; being able to have equal or different lengths, according to the terrain orography.

The operation of the invention incorporates a method of specifying the angle of rotation or inclination to be have each mirror at all times regarding the system of general coordinates of the field, consisting of the central beam of the solar beam that affects the central point of the mirror in question, which is the center point of its straight section, as it go in the optical or working plane, it is reflected on the point center of the face or active surface of the corresponding receiver, which means that the normal to the mirror at its central point coincides with the bisector of the angle that they form, in the optical plane, the projection on this plane of the mentioned incident ray and the straight that joins the central point of that mirror with the central point of the receiver, the latter being referred to as the reference line of the mirror straight.

For this, the situation angle of this line, which joins the central point of the mirror in question with the center point of the receiver, like the angle that forms this straight regarding the positive axis of abscissa of the general system of coordinates, which is parallel to the horizontal of the place. All lines have their corresponding situation angle, in the system general coordinate of the device, with respect to the axis of abscissa, always counted in a levógiro sense, from the semi-axis positive abscissa In particular, the central rays of the solar radiation beams have an angle of incidence on the horizontal that will be given by astronomical data for each moment, although said angle of incidence must be defined in the work plane, and therefore corresponds to the projection of the solar radiation on this plane. The tilt prescription of each mirror is that the normal to the mirror at its central point has a situation angle which is the semi-sum of the situation angle of the reference line of the mirror and the angle of incidence of the solar radiation, all in its expression or in its projection in the work plane, and remembering that all these angles are measured with respect to the positive axis of abscissa, in a levógiro sense

The invention includes a variant in the prescription of the parable's approach to the central point of the active face of the receiver, as this approach can produce values very high radiation intensity around said point. The variant consists in defining as the focus of the parable a point beyond the above center point of the active face of the receiver, although the new focus must be on the same line that unites the center of the mirror with the center point of the active surface of the receiver. The distance between the center point of the active face and the focus can be defined by design in a specific application, fixing in general the distance between the center point of the face active and focus as a fraction of the distance from the center from the mirror to the center of the active face of the receiver, selecting said fraction between 0 and 1. The basic prescription of this variant is that said distance is proportional to the distance from the center of the mirror to the center of the active face of the receiver, in the same proportion as the maximum drift of rays reflected from the mirror with respect to its width.

In the assembly according to the meridian, being the symmetrical arrangement with respect to the double receiver, the centers of the mirrors, which are its centers of rotation in the work plane, are preferably placed on a horizontal line, that is, they are all mirrors at the same height, because a few hours will receive the solar radiation from the East, and others from the West.

In the assembly according to the parallel, the lighting effective is always from the South, in the Northern Hemisphere, and from the North in the southern hemisphere, except in tropical areas, and except for very early in the morning and very late at sunset, when the sun it is, in late spring and early summer, farther north than the local parallel, in the northern hemisphere, but then its Lighting is not thermally effective speaking. This asymmetry of lighting makes, for the field of mirrors north of the receiver, in the northern hemisphere, the height of the centers of the mirrors on the work plane, and therefore at local altitude, can increase as the mirrors move away from the receiver, to have a better reflectivity of the radiation on it, with the only shadow limitation that the last mirrors would cast about the next set of receiver-mirrors that can be found further north of the whole that is being considering, in the northern hemisphere. In the southern hemisphere there is the symmetric situation, with respect to the equator, and the increase of that height is applied to the fields south of the receiver.

As a culmination of the explanation of the invention It is important to note that, while it is a device High concentration, the invention is applicable to any purpose, as the receiver can be configured with selected devices between thermal type, photovoltaic type, or other type of phenomena that involve physical-chemical transformations or molecular by radiation action.

Explanation of the figures

The figures, in general, are not to scale, because the relative sizes of the elements are very different; by For example, the width of the receiver and mirrors will be noticeably less than the distance from the receiver to the mirrors, and also very less than the height at which the receiver is supported.

Figure 1 shows a diagram, in section straight, of the solar device, corresponding to a double mount reflector, or dual mount.

Figure 2 shows the three-dimensional scheme of a receiver-mirror assembly in the assembly according to the parallel, with northward arrangement of the parallel in the hemisphere north.

Figure 3 shows a cross section of the ray reflection on a parabolic mirror arch, in the solar situation chosen as a reference, showing the concentration of rays on the focus of the parabola, which coincides with the center of the receiver. It serves to determine the parable in question. It does notice that the symbols included to identify the incident ray with its reflected, and both with its bisector, are specific to each figure, so they cannot be used to analyze others.

Figure 4 shows the same focused mirror for another solar position. The phenomenon of drift of the extreme rays

Figure 5 schematically shows the section straight from a mirror that revolves around its center point, in a assembly according to the parallel and south of the receiver (in the hemisphere North), from the position considered effective solar ortho to that of maximum height of the sun, passing through an intermediate taken from reference, indicating the drift of the rays reflected from each extreme.

Figure 6 shows the geometric scheme of calculation of the drift value of the rays reflected from a mirror like the one in the previous figure, between the two situations extreme position of the sun for a typical case.

Figure 7 shows the dimension scheme of the device, with a field of mirrors serving a receiver, and the inclination of the latter with respect to the horizontal and the mirrors in general.

Figure 8 shows the diagram of an assembly according to the parallel, with the mirrors north of the receiver, in the Northern hemisphere, pointing out the elements for the calculation of the arc Parabolic of each mirror.

Figure 9 shows the diagram of an assembly according to the parallel, with the mirrors north of the receiver, in the Northern hemisphere, indicating the representative angles of the turn of a mirror along the path of the solar path daytime

Figure 10 shows, enlarged, the angles representative presented in figure 9, to calculate the Drift of the rays at the ends of the mirror.

Figure 11 shows the coordinate system X *, Y * as more suitable for the construction of the parable of the mirror.

Figure 12 shows the variant of the approach of the parable, to a point beyond the central point of the active face of the receiver.

Figure 13 shows an assembly according to the parallel, with mirrors north of the receiver, in the hemisphere North, with increasing elevation in the central points of the mirrors consecutive.

Embodiment of the invention

To facilitate the understanding of the figures of the invention, and its embodiments, will now be relate the relevant elements of it:

one.

Solar radiation receiver, whose transverse width of its active face, where it affects and absorbs the radiation, is R. It can take various positions depending on whether the assembly is according to the meridian or according to the parallel, but its properties are generic, and it is mounted on pillars or rods that they support it at a considerable height on the ground. The receptor It may consist of various elements according to its purposes. May be a set of photovoltaic cells; or a bundle of tubes radiation absorption within which a fluid circulates heater; or any other provision to fulfill the function of energy collection reflected by the field of mirrors. In the Figure 1 shows two receivers placed symmetrically, in a double or dual mounting.

2.

Receiver surface or active face (1), whose transverse width is R, where radiation is absorbed concentrated solar.

3.

Point central segment representing the active face (2) of the receiver (1), in the definition work plane of the invention.

Four.

Direct solar radiation.

5.

Longitudinal mirror that reflects the original solar radiation on the receiver (1), and that is closer to the receiver

6.

Solar radiation reflected by mirrors (7).

7.

Generic mirrors that reflect the solar radiation (4) on the receiver (1). There is a plurality of parallel mirrors in all of them, which reflect the radiation on the same receiver (1).

8.

Stands or tall pillars that maintain in its height and position to the radiation receiver (1) and all its internal elements

9.

Low pillars that keep in your height and position to the axes of the mirrors, generically represented by (7).

10.

Axis of system ordinates (X, Y) in the work plane for a field of mirrors determined, and is the vertical axis that passes through the point center (3) of the active face (2) of the receiver (1).

eleven.

Axis of abscissa of the system (X, Y) in the work plane, which is the horizontal line passing through the center point (88) of the mirror (5) closest to the receiver (1), and is therefore perpendicular to the axis of ordered (10).

12.

Origin of coordinates, which is the intersection between axes (10) and (11).

13.

Axis vertical symmetry in dual assemblies, other than the axis (10) which is the axis of ordinates in the coordinate system of reference.

14.

Axis length of a generic mirror (7), around which it rotates to acquire the precise transverse inclination for the focus solar.

fifteen.

Rotating junction, thanks to bearing, abutment (9) with the axis (14) of rotation of the generic mirror (7).

16.

Firm receiver clamp (1) to the staff (8), at the top, allowing dilation in vertical of the receiver, maintaining its inclination angle. You can adopt various configurations.

17.

Cross Bracing Cables of the pillars or staffs (8).

18.

Upper stiffening cross member the receivers (1) in double or dual assemblies.

19.

Interior elements of the receiver (1). It can be a set of longitudinal tubes, inside the which circulates the heating fluid that takes most of the heat deposited by radiation on the active surface (2) of the receiver (1); or it can be the set of photovoltaic cells and cables in the case of the photovoltaic application, or the elements of any other radiation harnessing system concentrated.

twenty.

Generic angle of situation of the incident sunrays (4). This angle is specified with another numbering when applied to specific circumstances that require well defined differentiation.

         \ global \ parskip0.950000 \ baselineskip
      

twenty-one.

Situation angle from normal to mirror in its central point. It is an essential element for the approach of Each mirror

22

Normal to the mirror (7) at its point central (25). It is specified with another specific numbering when applies to circumstances that require differentiation well defined.

2. 3.

Land and foundation.

24.

Mirror farther from the receiver, used to determine the width R of the active face (2) of the receiver (one).

25.

Center point of a generic mirror (7) on the work plane.

26.

Thunderbolt of original sunlight incident at the center point (25) of a generic mirror (7).

27.

Normal to the mirror (7) at its point central (25). It varies depending on the rotation of the mirror. The normal ones (27a, 27b and 27c) are perpendicular respectively to the tangents (45a, 45b and 45c).

28.

Thunderbolt reflected from point (25), by incidence of lightning (26), being the normal (27) bisector of the angle formed by the rays (26) and (28).

29.

Thunderbolt of original sunlight incident at the end (35) of a mirror generic (7).

30

Normal to the mirror (7) at its end left (35).

31.

Thunderbolt reflected from point (35), by lightning incidence (29), being the normal (30) bisector of the angle formed by the rays (29) and (31).

32

Thunderbolt of original sunlight incident on the far right (36) of a generic mirror (7).

33.

Normal to the mirror (7) at its end right (36).

3. 4.

Thunderbolt reflected from point (36), by incidence of lightning (32), being the normal (33) bisector of the angle formed by the rays (32) and (3. 4).

35

Left extreme point of a mirror generic (7). It adopts various positions (35a, 35b and 35c) according to the position of the sun, depending on the arrival of the rays (46a, 46b and 46c).

36.

Right extreme point of a mirror generic (7). It adopts various positions (36a, 36b and 36c) according to the position of the sun, depending on the arrival of the rays (46a, 46b and 46c).

37.

Apex of the parabola (44) that passes through the center (25) of the mirror and has its focus on the midpoint (3) of the active face (2) of the receiver (1) being its axis of symmetry (43) parallel to the original sunrays (26, 29, 32).

38.

Axis of ordinates of the system (X '', Y ''), parallel to the Y axis (10) but located its origin in coincidence with the apex (37) of the parabola (44).

39.

Axis of system abscissa (X '', Y ''), parallel to the X axis (11) but located its origin in coincidence with the apex (37) of the parabola (44).

40

Axis of ordinates of the system (X ', Y'), coinciding with the axis of symmetry (43), with its origin coinciding with the apex (37) of the parable (44).

41.

Axis of abscissa of the system (X ', Y'), perpendicular to the axis of symmetry (43) and located its origin in coincidence with the apex (37) of the parable (44).

42

Angle formed by the axes (40) and (38) with the apex (37) as the vertex, which is the same as that formed by the solar rays of the reference situation with the vertical of the place. It is identified by A42.

43

Axis symmetry of the parabola (44) parallel to the sun's rays originals (26, 29, 32) and passing through the central point (3) of the active face (2) of the receiver (1).

44.

Parable passing through the center (25) of the mirror and has its focus on the midpoint (3) of the active face (2) of the receiver (1) being its axis of symmetry (43) parallel to the original sunrays (26, 29, 32).

Four. Five.

Straight tangent to the parabola (44) in the center (25) of the mirror (7). It is represented exclusively for three positions (45a, 45b and 45c) in figure 5, corresponding to three focusing positions of the mirror on the active face (2) of the receiver, for three positions of the sun on the work plane, represented by the rays (46a, 46b and 46c) respectively. Their respective normals are (27a, 27b and 27c).

         \ global \ parskip1.000000 \ baselineskip
      

46.

Thunderbolt solar incident in the mirror (7) at its central point (25). Mirror it turns to focus on the sun, so that its normal in the center (27) is the bisector between the incident ray (46), and the line (48) that joins the central point (25) of the mirror (7), with the center point (3) of the active face (2) of the receiver (1). Straight (48) is fixed, but not the normal one (27) that must accommodate the focus, depending on the position angle of the central sunbeam (46) which is represented exclusively by the rays (46a, 46b and 46c) in three solar positions, corresponding respectively to the situations:

to.

Reference situation, in which the parable of the profile of that mirror.

b.

Situation of effective solar ortho, which is the height at from which the heating produced by the sun is cash.

C.

For assembly according to any direction it represents the maximum height reached by the sun, in the corresponding plane of work, being 90º both in the assemblies according to meridian and parallel (unless you choose another value, in an application determined).

47

Angle of incidence of the beam (46) in the three solar positions characterized, in the figures, only by (46a, 46b and 46c) to which the angles (47a, 47b and 47c). The angle A47a is that of the reference situation, and is worth 90º for assemblies according to the meridian. For assemblies according to parallel, in the northern hemisphere, with the field mirrors to the south of the receiver, the angle taken as the reference position corresponds to the semi-sum of 90º with the angle of solar height maximum, which is the sum of the complementary latitude of the place plus 23º 27 '; and with the field mirrors north of the receiver, the angle of situation that is taken as reference has as value the semi-sum of 90º sexagesimal with the supplementary height angle maximum solar, the latter being the sum of the complementary angle of the latitude of the place plus 23º 27 '.

48.

Straight that joins the center point (25) of the mirror (7), with the center point (3) of the active face (2) of the receiver (1).

49.

Local horizontal line, shown rotated in figure 5 by reason of representing the drawing with Enough extension It is also the axis of abscissa of the system of general coordinates of the mirror field.

fifty.

Thunderbolt reflected from the right end (36) of the mirror (7) representing exclusively by lightning (50a, 50b and 50c). In its various positions (36a, 36b and 36c) according to the position of the sun, gives rise respectively to the rays (50a, 50b and 50c).

51.

Thunderbolt reflected from the left end (35) of the mirror (7) representing exclusively by the rays (51a, 51b and 51c). In their various positions (35a, 35b and 35c) depending on the position of the sun, gives place respectively to the rays (51a, 51b and 51c).

52

Circumference described by the ends (35 and 36) of the mirror (7) in its turn around its center (25).

53.

Circumference Diameter (52) perpendicular to the line (48).

54

Position angle from normal to mirror at its central point, representing exclusively by elements (54a, 54b and 54c), which varies from the position of reference (54a) to the focus on the sun in the effective ortho, (54b) or to that of the maximum solar height (54c) in the assemblies according to the parallel.

55.

Angle of position or situation of the straight (48).

56.

Ray position angle (parallel) that are reflected from the left end of the mirror, according to the positions it occupies (36a, 36b).

57.

Angle equal to the difference of angles (55) less (56).

58.

Angle formed by the tangent (45a) a the parabola at its center point, for the position with the diameter (53) perpendicular to the line (48).

59.

Angle formed by the tangent (45b) a the parabola at its central point, for the position of solar ortho effective, with the diameter (53) perpendicular to the line (48).

60

(Virtual) beam cutting point (51a) with the diameter (53).

61.

(Virtual) beam cutting point (51b) with the diameter (53).

62

Distance between points (60) and (61) which marks the maximum ray drift from the reference position from the mirror (7) to that of the effective solar ortho.

63.

Center point of the nearest mirror (5) to the receiver.

64.

Center point of the furthest mirror (24) to the receiver.

65

Straight that joins the center point (63) of the nearest mirror (5) with point (3) of the receiver.

66.

Straight that joins the center point (64) of the furthest mirror (24) with point (3) of the receiver.

67.

Line angle of the line (65).

68.

Line angle of the line (66).

69.

Bisector of the angle formed in the point (3) for the straight lines (65) and (66), being the visual bisector of the countryside.

70.

Angle of rotation in a mirror, in assembly according to the parallel with mirrors north of the receiver, from the lowest position of the sun, ray (46b), to the highest, ray (46c), this angle being the difference in situation angles of the normal in the center (25) corresponding to angles A54b and A54c

71.

Angle of rotation in a mirror, in assembly according to the parallel with mirrors north of the receiver, from the highest position of the sun, with tangent (45c) at the center point of the mirror, until it coincides with the diameter (53) that is perpendicular to the line (48).

72.

Angle of rotation in a mirror, in assembly according to the parallel with mirrors north of the receiver, from the lowest position of the sun, with tangent (45b) at the center point of the mirror, until it coincides with the diameter (53) that is perpendicular to the line (48).

73

Straight parallel to (48) at the end diameter right (53).

74.

Angle formed by the line (73) and the ray (50c) reflected from the right end of the mirror when occupies the position given by the tangent in the center (45c).

75.

First mirror of a couple consecutive of them, used in the procedure to determine the separation between them.

76

Center point of 75.

77.

Second mirror, of a couple consecutive of them, used in the procedure to determine the separation between them.

78.

Central point of 77.

79.

Angle that forms the line (90) that joins virtually points 76 and 78, with the horizontal.

80.

Angle of solar height above which should not be a shadow between consecutive mirrors.

81.

Thunderbolt solar with angle of height (80), which is tangent to two mirrors consecutive, each by one end (figure 13).

82.

Acute angle that forms with the horizontal the line that joins point 78 with 3.

83.

Acute angle that forms the tangent to mirror 77 at point 78, with the horizontal.

84.

Acute angle that forms with the horizontal the line that joins point 76 with 3.

85.

Acute angle that forms the tangent to mirror 75 at its point 76, with the horizontal.

86.

Acute angle forming the mirror 77 with line 90.

87.

Acute angle that forms the normal at mirror 77 at point 78, with the horizontal.

88.

Acute angle forming the mirror 75 with line 90.

89.

Acute angle that forms the normal at mirror 75 at its point 76, with the horizontal.

90.

Straight that virtually joins the points 76 and 78.

91.

Horizontal line that passes through the point 78.

92.

Thunderbolt solar with height 80, which affects point 76.

93.

Thunderbolt solar with height 80, which affects point 78.

94.

Normal to mirror 75 at its point central (76).

95.

Normal to mirror 77 at its point central (78).

96.

Thunderbolt reflected on point 3, from point 76.

97.

Thunderbolt reflected on point 3, from point 78.

98.

Tilt of the active face (2) of the receiver (1) with respect to the horizontal.

99.

Angle formed by the normal to the face active (2) at its central point (3) and the line (48) that joins this point with the center (25) of a mirror.

100

Angle, type 99, formed by the normal to the active face (2) at its center point (3) and the straight (66) which joins this point with the center (64) of the furthest mirror (24). Being type 99, it has not been represented in figure 7, since 99 It is sufficiently explanatory, and both angles cannot overlap in the figure, they would be indiscernible.

101.

Upper end of the first mirror (75) used to determine the distance to which the next mirror (77).

102

Lower end of the second mirror (77) used to determine the distance to be placed from the previous mirror (75).

103.

Axis And * of ordinates that have their origin at the central point (25) of a generic mirror (7), and is parallel to the Y 'axis (40).

104.

Axis X * of ordinates that have their origin at the central point (25) of a generic mirror (7), and is parallel to the X 'axis (41).

105.

Polar coordinate angle with center at the central point (25) and used to describe the circle (52) radius (E / 2).

106.

Focus point beyond the point central (3), in this variant.

107.

Distance between points (3) and (106) on the line (48).

108.

Virtual surface, parallel to (2) where the alternative focus lies (106)

Given the importance of several angles for the specification of the invention, hereafter It makes a relationship of these. They are identified by the letter A followed by their reference number, and are used with this denomination in the explanation of the embodiments. The angles are in several situation cases of a line, and in that case they are measured in the sense levógiro from the positive axis of abscissa of the system in which are defined, which can be the general of the field, or the specific of a mirror

A42 (element 42) is the complementary angle of the angular height of the sun on the work plane. Angular height of the sun is represented generically by A20 (element 20).

A47a, which is the reference angle of light solar, as explained in element 47.

A54, situation angle from normal to a mirror in its central point.

A55, which is the angle of the straight line that joins the central point of a mirror with the central point of the receiver. There is therefore an A55 for each mirror.

A74, angle of inclination of the beam coming out of one end of the mirror in focus position in position of reference, with respect to the line (48).

A98, inclination of the active face (2) of the receiver (1) with respect to the horizontal.

A99, angle formed by the normal to the face active (2) at its central point (3) and the line (48) that joins this point with the center (25) of a mirror.

A100, angle, type A99, referred to the mirror further away (24).

There are several more angles, in particular referred to the determination of the distance between central points of consecutive mirrors, as seen in figure 13, which follow the naming pattern given here, even if they are not situation angles referred to the axis of abscissa, but any.

It is also pertinent to list a set of capital letters that have particular relevance in the explanation of the invention, and in its materialization:

D is the distance from the center point (25) of a mirror to the center point (3) of the active face of the receiver (one).

Dmax is the maximum value of D, which corresponds to last mirror (24) of the field (the furthest from the receiver (1)).

E is the width of a mirror, which is determined depending on the drift produced, so that it is bounded to a fraction of R.

F, focal length, which is the focus distance at the apex. In figure 3 it corresponds to the distance between the point center (3) of the active face of the receiver (1) and the apex (37).

H is the height of the center point (3) of the receiver (1), on the origin of coordinates (12).

K, trigonometric coefficient that determines the width E.

M, slope of the sun's rays in the reference situation.

P is the quotient between the maximum ray drift which is supported in mirrors, and the value of the visual width W of the active surface (2) of the receiver.

Q mirror quality factor, which is greater than 1 when the mirror is of good quality and its tolerances of manufacturing do not introduce significant deformations in the lightning reflection; and is less than 1 when introduced. In this invention its value is limited between 0.5 and 2.

R is the transverse width of the active face of the receiver (1), which is equal to the distance from the central point (64) from the furthest mirror (24) to the center point (3) of the face active receptor (1), divided by 107; and also divided by a quality factor Q of said mirror; and also divided by the cosine of angle A100, which is the particularized A99 for said mirror.

T is an angle that modifies the inclination of the active face of the receiver, depending on the orientation want to give respect to the bisector of the field.

V is the maximum drift of the rays in a mirror, which depends on the construction data and the type of assembly, as well as the reference situation of the sun chosen by design.

W is the visual or apparent transverse width of the active face (2) of the receiver (1), as seen from the center of a mirror, which is equal to the value of R multiplied by the cosine of angle A99 of the mirror in question.

Additionally, various series of coefficients (C1, C2, C3) and (J, S, U) that serve simply for Better express the parabolic equations.

In order to materialize this invention, a set of tall pillars or rods (8) that form a row longitudinal as shown in figures 1 and 2, with the receiver (1) in said row of pillars, generally in version dual, although in some assemblies according to East-West it you can opt for a single receiver, as in figure 2. In parallel to that row is arranged the set of longitudinal mirrors (7), supported on their solid axes of rotation (14), in turn supported by rows of low pillars (9), which connect with the previous ones in the pieces (15). Given that the arrangement is uniform in a longitudinal direction, and may have the required length, The description of the invention and its quantitative requirements are perform in the corresponding work plane, which is always normal to the longitudinal mounting shafts, which are mutually parallel

A set of mirrors is also available. (7) of elongated rectangular shape, which may be made of any reflective material, the mirrors having a frame lower structural to maintain its shape and be rotated around its longitudinal clamping axis (14) that coincides with the axis of symmetry of the specular surface. These mirrors are sit on low pillars (9), provided on their upper bumper of a clamp that clings to a bearing (15) which in turn holds the structural axis (14) of rotation of the mirror (7). They are mounted in parallel Several mirrors of these characteristics. Your location comes determined by a fixed point, which is its central point (25). This location is fixed consecutively, starting with the mirror more close (5) to the receiver (1) whose location is chosen by the concrete application of the invention. In the extreme option, the abscissa of the central point of that first mirror can be 0, is say, that is in the vertical of the central point (3) of the face Active receiver. Allowed variants are any, in function of the inclination of the active face (2) of the receiver, although in turn this is dependent on where the first mirror is located (5) and the last (24). As a prescription, the angle of situation of the line that goes from the center point of the mirror more close (5) to the center point (3) of the active face of the receiver, You have to choose between 90º and 110º. From there, the mirrors are they have contiguity, leaving between two consecutive only the assembly tolerance, evaluated between 0.1% and 5% of the average of the widths of consecutive mirrors, so the prescription fundamental is that of width, identified by E. The invention includes a variant to determine the separation between mirrors consecutive, whose centers may even be at different levels, and which is developed later, in relation to figure 13.

The height at which the receiver is located and the transverse length of the field of mirrors, as well as the dimension longitudinal of the receiver and mirrors, are design parameters which are selected based on the radiation concentration solar that is intended to be obtained at the receiver, and does not limit the application of the invention Nor is the material limited employees in each component of the system, although for reasons elementary said materials should present the properties optical and thermal appropriate to its function, and mirrors, by example, they should have a high reflectivity to the photons of direct solar radiation

In the basic assembly of the mirror field, the center points of the mirrors are all at the same height, which is the height of the center (63) of the nearest mirror (5) to the receiver, which is the one taken as a reference to fix the abscissa axis of the general coordinate system of the field. Now it fits the variant that each center be at a different height, having said case a specific abscissa axis to define the profile of said mirror, which will be the horizontal line that passes through the center of the mirror in question, which in turn will have an order given in the general field coordinate system. That allows unambiguously Define the complete assembly of the device.

To determine the value of E it is necessary previously determine the drift of the rays reflected by the mirror, particularly from its ends, when it rotates to maintain the sun-receiver approach. In turn, the lightning drift depends on the normal lines to the mirror at its point central and at its ends, so it is indispensable, as a step prior fundamental in the invention, determine the parabola (44) that passes through the center (25) of the mirror and focuses on the point central (3) of the active face of the receiver, being its axis of symmetry (43) parallel to the rays of the original sunlight (26, 29 and 32). In that determination the apex of the parable (37), which is also used as the origin of two systems of coordinates:

-

he (X ', Y') whose axes are respectively (41) and (40) and is the system natural definition of the parabola, because its Y axis coincides with the axis of symmetry (43), and its coordinate origin coincides with the apex (37) of the parable;

-

he system (X '', Y '') that is parallel to the system (X, Y) and has as axes, respectively, the (39) and the (38), and their coordinate origin It coincides with the apex (37) of the parabola.

Thus, it is necessary to perform certain steps of analysis with certain hypotheses in the values of certain variables, After completing the analysis, go back to leave these variables consistently set. The objective of the invention is to determine the specifications of

-

situation and measures of the receiver longitudinal, particularly the height H of the central point (3) of its active face (2) and its transverse width, R, as well as its tilt (98);

-

situation, specific form and measures of each mirror, for which it is necessary to start from the location, chosen by design, from the center of the first mirror; to which the determination of its shape and width; and subsequently it has to apply that same pattern to successive mirrors, for which it is It is necessary to have a criterion to determine its width, because this is essential to define the center of the following mirror.

To achieve this objective, it is carried out Then the following sequence of analysis:

-

determine the parabolic shape corresponding to the focus coinciding with the center point of the active face of the receiver, and pass through the center point of the mirror, whose coordinates are assumed to be known (Xc, 0); and also choose, by design, the value of the solar height above the horizon local, which corresponds to the astronomical reference situation that it is used for this determination;

-

determine the drift of the rays reflected by the mirror, when it rotates to meet the criteria focusing on the sun and the receiver, the drift being the displacement lateral, in parallel, of the rays reflected from the same point of the mirror, when it turns by prescription of the focus;

-

determine from there the value of the width of the mirror, so that the drift does not exceed a fraction, P, of the width of the receiver; thus having the criteria necessary to materialize the invention.

The parabola equation in its natural system it is easily written based on its focal length, F, which is the distance from the focus to the apex, which in this case corresponds to the distance between the center point (3) of the active face of the receiver and the apex (37). The first is defined by design. The apex (37) must be determined for each mirror, depending on the location of its only fixed point, which is its center (25).

The equation in question is

101

Now, the apex (37) is not determined, so that the first analysis to perform is to determine their coordinates (X_ {0}, Y_ {0}) taking as known data

H, point height (3)

Xc, center abscissa (25) of the mirror, setting void your ordinate (Yc = 0). In many cases, all centers of mirrors will be at the same height; but they are expected to be at different height. In this case, H is expressed as height above the center point of the mirror in question being calculated, The Calculation results are then expressed in the general system of ordinates, by mere translation of the abscissa axis.

A42, angle (42) complementary to the height angular of the sun. In figure 3 it is represented for the case of assembly according to the parallel, with the field of mirrors south of the recipient, in the Northern Hemisphere, and by convention that is taken angle as positive. In figure 8 it is represented for the case of assembly according to the parallel, with the field of mirrors north of the receiver, in the Northern Hemisphere, and the angle has to be taken then as negative, which implies a difference in the equations, in particular when choosing the sign of the square roots that appear In the calculation.

The determination of the parable (44) and therefore of the mirror profile, it is made for a position of the sun, which called reference; therefore, out of that position, the parable of the mirror, which will have experienced a turn, will have lost its optical-geometric properties. That will force a second analysis, which is the determination of the drift of the reflected rays.

Enter the coordinates of a certain point in the various reference systems exist specific relationships, but these in turn depend on the assembly chosen for the device, in which essentially three cases are distinguished:

-

assembly according to the parallel, with the mirrors south of the receiver, as seen in figure 3;

-

assembly according to the parallel, with the mirrors north of the receiver, as seen in figure 8;

-

assembly according to the meridian, and any in which the position of the sun in the zenith, on the work plane, for which any of the previous representations, and especially figure 7, but taking into account that in general there will be two symmetric fields, to lift and west of the receiver line, which in general will be dual.

In assemblies according to the parallel, the specific relationships between coordinate systems are the following. Between (X '', Y '') and (X, Y):

102

where X_ {0} and Y_ {0} are the coordinates of the apex of the parabola in the system (X, Y).

Between (X '', Y '') and (X'.Y) you have:

103

Take into account the above for the angle A42, which is positive if the field is mirrors is south of the receiver; and negative if it is north. This does not affect the sign of cosine, which is always positive, but yes to the breast, because odd function Between (X, Y) and (X ', Y') you have:

104

So the parable equation remains

105

The focal length F is calculated based on the coordinates of points (3) and (37), particularly in the system (X, Y) which is where the device is to be defined, because the other systems are dependent on the mirror that is being calculated. For this, it is taken into account that the abscissa of the point (3) is null, and its ordinate is the height H. It has:

106

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On the other hand, both the focus and the apex of The parabola are on the axis of symmetry (43). The slope of this axis is M,

107

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The value of M is positive if the mirror field It is south of the receiver; and negative if it is north. Throughout case,

108

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Therefore the focal length can be expressed according to the situation of the field. With field of mirrors south of receiver is

109

Where the minus sign has been taken in the result of the square root because F has to be positive (it is a distance in absolute value) and X_ {0} is negative, since the apex of the parabola must be on its axis of symmetry, and said axis is of positive slope (M) and its ordinate at the origin is H (the focus) by what X_ {0} will be unconditionally negative (not Y_ {0}, that it can be positive or negative). The case with the field of mirrors at North is completed later.

This expression of F leaves as the only unknown, in the equation of the parabola, the value of X_ {0}, because it also use equality;

110

The parable (44) must pass through the central point of the mirror (25), whose coordinates in (X, Y) are (Xc, 0); condition that provides the equation

111

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The equation can be grouped by terms homogeneous in X_ {0}, resulting

112

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Now, in the second member, the parenthesis that multiplies X_ {0} is identically null, by the definition of M,

113

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In turn, if you multiply the entire equation of the parable for -X_ {0}, remains

114

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For better handling of the parabola equation its terms can be rearranged and coefficients defined

115

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Which leads to reformulate the expression of the parable, applied to the apex, as

116

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Being the solution sought that produces a negative value of X_ {0}, since the other solution would correspond to the symmetric parabola with the concavity down and the apex by above focus, which would be useless for the reflection of the solar radiation, which comes from above. Note that C1 is Always positive and C3 is always negative. The valid solution is:

117

In turn, the ordinate of the apex is

118

The parabola equation in the general system of coordinates is

119

Where A42 and M are common values for all mirrors, but not X_ {0} and Y_ {0}, which depend on the position of each mirror (because they depend on Xc).

In the case of the mirror field north of the receiver, in the northern hemisphere, there are small variations in the analysis, because the relative situation sun-mirrors reverses from semi-flat, and it has already been said that A42 is negative in that case. On the contrary X_ {0} is unconditionally positive, what makes the focal length should now be expressed as

120

having chosen the solution positive, because X_ {0} is. Precisely for this reason, and for being M and A42 negative, the coefficients of the equation are redefined how

121

in what you have to keep in mind that C1 is always positive, and C3 always negative; being the expression of the parable, applied to the apex, the next

122

Whereby the apex abscissa is

123

That always provides a positive value of X_ {0}. In turn, the ordinate of the apex is

124

with M = tg (90º - A42)

being its negative value, because A42 it is, and the resulting angle is greater than 90º, being in the second quadrant.

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The parabola equation in the general system of coordinates is

125

Where A42 and M are common values for all mirrors, but not X_ {0} and Y_ {0}, which depend on the position of each mirror (because they depend on Xc).

There is a particular case that cannot be resolved with this general method, and it is the one that corresponds to the sun at the zenith, then A42 is null, and the slope M acquires infinite value, making the equation undetermined. It is precisely the case of assemblies according to the meridian. However, the resolution of this mathematically singular case is trivial, because then the axis of symmetry of the parabola, which has to be parallel to the rays central to the sun, is vertical, and corresponds to the axis of ordinates, where is the point (3) at a height H. The apex will be in that same axis, and only Y_ {0} will have to be determined because X_ {0} is null. Plus still, the axes (X'.Y ') are a translation downwards, until the ordered Y_ {0}, of the system (X, Y), and the parabola equation It can be written

126

And the relationship between systems is

127

128

And in turn the focal length in this case is

129

Remembering that Y_ {0} is negative, and that logically F must be greater than H. The equation of the parabola in the system (X, Y) is therefore

130

Particularizing for the central point of the mirror, coordinate (Xc, 0)

131

That transforms into the second equation grade

132

Being the valid solution

133

That is always negative, and has a limit of 0 when the value of Xc becomes 0, that is, when it falls below the point (3) in its vertical, and it is also the apex.

This prescription applies when the assembly is according to the meridian, and in any other case in which the position of reference be with the sun at the zenith in the work plane.

With the analysis performed, everything is already known about the parable (44) for a given mirror, being in general its focal length, F

134

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And the equation of the parable whose profile has that mirror, in general is:

135

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from which you can get your pending, differentiating

136

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that for the central point (25) of mirror is concrete in

137

This value is important, particularly because determines the slope of the normal at the center point, Nc, that is

138

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Both the tangent (45) at the central point and the slope (27) serve to represent the position of the mirror.

Each mirror is made to follow the same pattern of spin specifications to provide focus to the sun included in the invention, and which is done using as a tool the normal one (27) to the mirror (7) at its central point (25). The mirror is turn until this normal coincides with the angle bisector formed by the central beam of the solar beam incident at the point center of the mirror, and the line (48) that joins said central point (25) with the center point (3) of the active surface of the receiver, expressed all this in the projection in the optical plane or of job. The mirror is spinning as the sun advances in its daytime path, from a position of the sun called ortho cash, which is from which it is relevant for purposes practical radiation received, and continues to turn until sunset effective, when those practical effects disappear.

The effects of that mirror rotation are evident with the help of figure 4. In it you see the generic mirror (7) in a different position from the reference one (in figure 3) with the solar rays (26, 29, 32) arriving very oblique. In particular is important the ray (26), which is the central ray of those that affect at the center point (25) of the mirror. His reflected beam goes through the straight (48), and by prescription the approach affects (always, in all position of the sun) at the center point (3) of the active face (2) of the receiver. Now the other rays, and in particular those that they affect the ends of the mirror, which are the rays (29) and (32), since they do not affect point (3), which is where they would affect the situation reference.

In this context the concept of drift, which is the lateral displacement, in parallel, of the rays reflected from the same point of the mirror, when it rotates by focus prescription. This drift is null for the center point (25) of the mirror, but it is not for the other points, and it is so much greater the further the point considered from the center of the mirror, so you have to consider the drifts of the extremes in the criterion of determining the width of the mirror.

For these purposes it is essential to remember that the angle formed between the normal (27) at the center point of the mirror (25), and the normal one at any other point of the mirror, remains in rotation, because the mirror is considered undeformable. In particular, the normal (30) at the left end (35) will form always the same angle with the normal one (27) at the center point. This it has an important effect: the reflected ray (51) from that end (35) propagates in a path parallel to the ray (31) reflected from that end (35) in the reference situation, expressed in figure 3. However, as the end in question it no longer occupies the same point in the work plane, because it has rotated (in figure 4, and in general), the reflected ray (51) no longer impacts at the receiver at point (3) but at a different point, whose distance to point (3) is to be calculated, and that is what constitutes the drift.

It is very important to point out this property of rotating mirrors, whatever their geometry, because the shape is keeps in the turns, and the values of the angles that form any two normal, corresponding to two well defined points of the mirror. The property states that solar rays reflected from a certain point of the mirror will be parallel to each other, for the various turns of the mirror, if the mirror it turns to focus on solar radiation in such a way that the beam reflected from the center point and mirror pivot follow always the same trajectory (which in this case is the one that goes from that pivot point (25), to the center point (3) of the active surface of the receiver).

This effect of lightning drift is perfectly quantifiable simply by knowing the positions extreme astronomical of the sun, in its projection in the plane of work, and their relationship with the reference situation, the which has to be astronomically representative, that is, represent the situation when solar energy has a value relevant, because that is when the parable is perfectly focused on the central point of the receiver. The drift determination is set for each type of device configuration radiation concentrator, although it always obeys them beginning.

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Mounting according to the parallel, with the mirrors south of the receiver (in the northern hemisphere)

For mounting according to the parallel, with the mirrors south of the receiver (in the northern hemisphere) is determined with the help of figures 5 and 6, which show how to turn the mirror, which is denoted by its tangent (45) at the central point (25), which materializes respectively in the tangents (45a, 45b and 45c) for the reference position, for the height at its ortho effective solar in winter, and for the maximum height reached by the Sun throughout the year, on the work plane, which are 90º. The reference position is in the middle, but closer to that of maximum height, it is for those positions when more intensity provides sun When describing in the list of elements the number (46), which is the solar beam incident at the center point of the mirror, the geometric situation was explained, in this case of assembly according to the parallel, with the mirrors south of the receiver (in the northern hemisphere).

In figure 6 only the information concerning the reference position (a) and that of the effective solar ortho (b) because it is between them two in which produces the greatest drift, which is measured by the projection of the reflected beam displacement from its left end (in this figure, but the right one can be used) on the diameter (53) which is perpendicular to the line (48).

The ray (51a) that is reflected from the end left in position (35a) drifts to the beam (51b) when the mirror rotates, and its end occupies the position (35b). The virtual extension of these rays up to the diameter (53) can be seen in figure 6, in which are also identified a series of relevant angles to calculate the drift, which is the distance (62) that separates the points (60) and (61), which are the virtual cutting of (51a) and (51b) with (53).

Between the angles of that figure are established The following relationships:

139

In turn you can write the following trigonometric relationships between the various points of the diameter (53), taking into account that the radius of the circumference (52) is half the width of the mirror, this is E / 2. The points are identified by their numbering, and the distance between them is the numbering difference.

140

So, the maximum drift, which is the distance between points (60) and (61) it turns out to be

141

Since angle A57 is very small, then corresponds to the angle at which half of the mirror is seen from the center point (3) of the active face of the receiver, drift can be approximate by

142

that can be expressed based on data constructive, as is the angle of position of the line that goes from the center (25) of the mirror and the center point (3) of the face active (2) of the receiver. Using the given relationships:

143

This drift value has been called V maximum, which must be limited to a fraction P of the width visual or apparent W of the active face (2) of the receiver, contemplated from the central point of the mirror in question (figure 7).

The existing relationship is

144

where A99 is the angle formed by the normal to the active face (2) at its center point (3) and the straight (48) that joins this point with the central (25) of the mirror. So:

145

If the following coefficient is called K trigonometric

146

It has

147

The K factor is always positive, since A47a It is always greater than A47b. In turn the K factor can be broken down as follows:

148

The factors in A55 are dependent on the constructive geometry, while the parentheses only depend on Solar evolution in the work plane.

It is important to quantitatively analyze the E value for representative situations. For example, if take the following values for the representation of the sun

149

And a value P = 0.1 is adopted, can be obtained the values of E as a function of R, for various positions of the center of the mirror If this is right on the vertical of the point (3), A55 is worth 90º, and you have

150

For what you get

151

If the value of A55 is taken as 120º, which is representative of an intermediate mirror in the field, you get K = 0.159, so that the width of the mirror E remains,

152

Finally, you can take A55 = 150º for the furthest mirror, and it is

153

So the width is approximately

154

As the mirror separates from the receiver, it must be smaller, and with the previous formulation it is quantified this property.

Assembly according to the meridian

Although the previous geometry has been specified as own of assemblies according to the parallel, with the mirrors to the south of the recipient (in the Northern Hemisphere) the methodology is valid for characterize an assembly according to the meridian, with the proviso that the reference solar position in this case must be the zenith local, because the sun will be half the time aside, and half in the other one. So, the characteristic will be

155

The formulation previously used for the assembly according to the parallel, in the Northern Hemisphere, with the mirrors south of the receiver, serves to determine the semi-space lift. In it, A55 of any mirror will be greater than or equal to 90º.

Obviously, the mirrors should be symmetrical with respect to the middle plane of the device, where they will be install two receivers at the corresponding height, each looking at a semi-field of mirrors, one to lift, Another west.

Figure 7 shows the scheme of a field of mirrors in the assembly according to the parallel, with the mirrors at south, in the northern hemisphere, but the arrangement of figure 7 is also applicable to a mounting according to the meridian, in a semi-flat Figure 7 represents only the half of the installation in the assembly according to the meridian, where it must use the own symmetry of daytime solar evolution (in the work plane) to exploit the elements more efficiently Construction used. Figure 1 represents both semi-flat, up and west.

Tilt of the receiver

In Figure 7 the centers of the first and last mirror, corresponding respectively to the elements (63) and (64). Also important are the straight lines that unite those points with the center point (3) of the active face of the receiver, and that are respectively the elements (65) and (66), which have as situation angles elements (67) and (68). The length of the segment (66) between points (3) and (64) is the distance Dmax, used to determine the width R of the active face (2) of the receiver.

The bisector (69) of the angle formed by the lines (65) and (66) at point (3) is called the visual bisector of the field of mirrors, and the receiver is positioned with an inclination in which his active face is normal to said bisector.

This means that angle A98 is worth

156

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As a variant, the invention allows a different inclination of the receiver, to take into account the quality of the closest and farthest mirrors, which may be different, providing that the active face is more perpendicular to the area with mirrors of higher quality. This leads to express, in general

157

where T is a value that select between -20º and + 20º, according to the application design of the invention.

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Assembly according to the parallel, in the Northern Hemisphere, with the mirrors north of the receiver

In the assembly according to the parallel, in the Northern hemisphere, the angle of situation that is taken as a reference It has as a value the semi-sum of 90º sexagesimal with the angle Supplementary maximum solar height, the latter being the sum of complementary angle of the latitude of the place plus 23º 27 '; what equivalent to the angle of the reference sunrays, with respect to the vertical axis, be negative, and corresponds to the value 90º minus the semi-above mentioned, having the sunrays of negative slope reference in the coordinate system of the installation. Figure 8 represents this situation, which was useful to determine the parabolic profile of the mirror. That information on the solar movement in the work plane for these assemblies It is completed with figure 9.

In this case, the angle of rotation of the mirror, A70 (70), to determine the drift corresponds to half the angle formed by rays (46b) and (46a). As lightning (46a) is very next to the line (48) that goes from the center of the mirror to the center of the active face, the latter can be used as a reference alternative to calculate drifts, using figure 10 as the basis to determine the drift, it is possible to define the drift. occurs when the sun is at the top of the work plane (which in principle corresponds to the vertical, but in the figures it puts, as a rule, any value), and Vb, which is when is in the lowest (but does not get 0, the horizontal, but an ortho cash). It has:

158

In the first case the maximum drift occurs in the far right, and in the second on the left. However, Since the angle A74 is very small, the effect can be considered it's symmetric, and for each case it is worth,

159

With these values you can determine the widths of the mirrors according to their position relative to the receiver, which It is measured by the value of A55. The width in question E will be the smallest of the two values set forth below, Eb and Ec:

160

Where the coefficient values Trigonometric Kb and Kc are

161

A55 being the position angle of the line (48) that joins the central point (25) of the mirror in question, with the center point (3) of the active face (2) of the receiver (1); Y where A47b (47b) is the location angle of the sunrays central (4) of each beam, in the situation of effective ortho, moment from which the effect of solar radiation on the receiver It is considered relevant in the design of a specific device; Y where A47c (47c) is the location angle of the solar rays when the sun reaches its maximum height in the plane of job'.

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Now, in figure 10 it has been assumed practical coincidence between the line (48) whose angle of situation it is A55 (55) and the reference solar ray (46a) whose angle of reference is A47a (47a), which is not exact, although it approximates a lot, and in figure 10, because of scale problems, they couldn't discern However, the algebraic formulation does require that discern, so the trigonometric coefficients Kb and Kc are must rewrite as

162

where abs (value) means absolute value of the amount that is within the parenthesis.

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As solar data to illustrate with an example, we can take

163

We first consider the mirror that is under the receiver, in its vertical, that is, A55 = 90º. It has:

164

The latter being the one that limits the value of E, what's left

165

And taking P = 0.1

166

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On the contrary, if we move away from the receiver, we find, for example for A55 = 135º

167

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Being older Go, so E is worth

168

Which means that in this case the mirrors they get older as they move away from the receiver, because they have What to make smaller turns. In this context the problem of shadows and optical interference between consecutive mirrors, which It reduces concentration efficiency.

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Distance between successive mirrors, in the field north of the receiver. Possibility of central points with increasing dimensions high

The invention, in addition to the basic prescription already given about the contiguity between mirrors, includes a variant particularly useful for assemblies according to the parallel with the mirrors north of the receiver, which allows no interference optics between mirrors, when the sun is above a height given, minimizing the separation between them, to obtain the maximum radiation concentration value. This variant also allows that the central points have higher and higher levels when moving away of the receiver, although the case of constant dimension is included in the general prescription In this case it is essential to take into account that the profile of each mirror has to be determined with its own reference system, as stated, in which the axis of abscissa moves so that the origin of ordinates (12) is at the same level than the center point (25) of the mirror.

In assemblies according to the parallel with the field of mirrors north of the receiver, in the northern hemisphere, in the which the height of the centers of the mirrors in the plane of work, and therefore at local altitude, may increase as that the mirrors move away from the receiver, given the situation symmetrical, with respect to the equator, in the southern hemisphere, in which the increase in said height applies to the fields south of the receiver, the separation between center points is specified (76 and 78) of two consecutive mirrors (75 and 77) depending on:

-

angle of solar height A80 (80) above which there is no interference optics between the mirrors,

-

angle A79 (79) formed on the horizontal by the line that joins virtually to the two central points above (76 and 78)

-

respective width of both mirrors, denoted respectively by E and E ',

-

angle acute, on the horizontal, of the line that joins each central point of a mirror with the central point (3) of the active face (2) of the receiver (1), said angles being the A84 (84) for the first mirror (75) and the A82 (82) for the second (77).

From the above, the respective angles of inclination of the tangent to each mirror in its central point, the angle A85 (85) being for the first mirror and A83 (83) for the second. The representation of the Figure 13, and specifically the angles A87 and A89 that are, respectively, complementary to A83 and A85. Which leads to

169

from which it remains specified the angle that forms the tangent to each mirror in its center point with the line (90) that virtually joins the points central (76 and 78), the angle A88 (88) being for the first mirror (75) and A86 (86) for the second (77), which correspond to

170

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which in turn specifies the distance Z between the center points (76 and 78) of both mirrors, measured on the line (90) that virtually joins them, being this value

171

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which in turn sets the separation in coordinates of their central points, which are identified by the letter X and Y followed by the point number, being

172

This prescription of the invention applies from the mirror (5) closest to the receiver, to the furthest (24).

The previous prescription can be materialized by various systems for determining their unknowns, which fundamentally they are X78 and Y78, which is the same as identifying Z as unknown. To determine these values so that it is met strictly the above prescription, which is what ensures the higher radiation concentration, for conditions specified, the following set of relationships, starting by identifying the case data, which They are:

Width E of the first mirror, determined by the maximum drift limitation procedure, according to the mounting.

Width E 'of the second mirror, determined approximately by the drift limitation procedure maximum, depending on the assembly, using an approximate value of coordinates of its central point.

X76 and Y76 coordinates of the center of the first mirror.

A85 angle of inclination of the first mirror.

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Coordinates of point (101) upper end of first mirror

173

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Having line 81, which marks the ray that rubs to the two consecutive mirrors, the following equation:

174

Value of angle A79. It can be specified a priori , or be an unknown to determine, or a value to select from several; but in the relations to be explained, it is assumed fixed (although successive determinations of the second mirror can be made, for different values of A79).

Value of A80, on which the same can be said reasonings that about A79.

Coordinates of the center point (3) of the face active receptor, which are X3 = 0 and Y3 = H.

The indexed variable Z_ {n} is defined as

175

Whose subsequent relationships are calculated from n = 1 onwards,

176

having made use of the mirror in every sequence "n" must be focused on point (3), so that its normal, straight 95, must be the bisector of the angle formed by the incident ray, with angle A80, and the reflected one, with angle A82_ {n}.

By having the value of A83_ {n}, the lower end point (102) of the second mirror

177

calculating on the other hand the ordered Y102 'n corresponding to line 81 for the value of the abscissa X102_ {n}

178

For case n = 1, the mirrors are too next, and the Y102_ {1} end of the second mirror is below point Y102 '1, so the difference

179

is negative.

When increasing the index "n", the value of DY102_ {n} increases, and the perfect prescription of the value of Z is its value that cancels this difference, which is obtained by interpolating between the values of Z_ {n} and Z_ {n + 1} that give the last value negative of that difference, and the first positive, respectively, applying the rule of the lever in the interpolation.

Constructive method of mirrors

Mirrors can be built with any material, selecting the properties to meet each of its parts, from structural to properly reflexive ones. The reflective surface is the one that requires special attention in the materialization of the invention, as it must follow the prescriptions of location, width and profile that have been given, and that have to materialize for each mirror; which is determined by its point center (25) and its width E, E / 2 being the turning radius around of said central point, leaving the extreme values of the arc parabolic of that mirror determined by its coordinates in polar, with center at the center point (25) of the mirror, and angle polar (A105) rotating counterclockwise from the axis of own abscissa of the mirror (104), finishing the mirror by each end at the points where it cuts to the circumference (52) centered on the center point (25) of the mirror and with radius (E / 2), whose polar coordinates are X * and Y *, which are determined at continuation.

In support of construction, although others alternatives are valid for this materialization, in figure 11 a replica of figure 3 is presented in which the coordinate system (X *, Y *) that has its origin at the point center (25) of the mirror (7) and its axes (104) and (103) respectively, they are parallel to those of the system (X ', Y') with their axes (41) and (40) and originating at the apex (37) of the parabola (44).

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Also using the systems (X, Y) and (X '', Y '') You can write the following relationships, where X_ {0} and Y_ {0} are the coordinates of the apex of the parabola in the system (X, Y).

180

And therefore

181

Already known X'c and Y'c, you have:

182

Like the parabola equation in the system (X ', Y') is

183

It can be rewritten as

184

To find where it cuts to the circumference (52) centered on the center point (25) of the mirror and with radius (E / 2), it use polar coordinates

185

What provides the equation that will give the two cut points, or mirror ends, points (35) and (36), which is

186

Transcendent equation, elementary to be solved by numerical or graphic methods, and that provides 2 values of angle A105, which in turn provide the values of the coordinates of the extreme points.

It should be noted that if the field measures are express in terms of (E / 2), the equation takes form dimensionless Calling

187

The equation is

188

which is indicative of the self-similarity of device.

Finally, although the mirrors have been defined of straight section corresponding to a parabolic arch, its curvature intrinsic is very meager, so they can be built with a polygonal profile to follow, by registered straight segments or circumscribed, the line of the parable in question.

Once the invention has been clearly described, notes that the particular realizations above described are subject to modifications of detail provided that do not alter the fundamental principle and the essence of the invention.

Claims (13)

1. Solar radiation concentrator, with Multiple independent parabolic mirrors, based on: a set of slightly concave mirrors (7) upwards, parallel to each other, of markedly geometry longitudinal, that is, with a length much greater than its width, which are rotatable around its axis of longitudinal symmetry (14), which in turn is the shaft that supports bearings, that settle on the pillars (9) that, every certain stretch of length, they are embedded in the ground and rigidly support the cited bearings, whereby the clamping shaft, which is also shaft turning, it is always fixed in that line position straight turning each mirror to reflect radiation to a solar receiver (1) of a longitudinal nature, located its axis of longitudinal symmetry at a height H above the mirror axis height (5) closest to the receiver (1), thanks to some rods or pillars (8) that support it, with an active face (2) which is where it receives the radiation (6) reflected by the mirrors (7), the active surface (2) having a transverse width R; the work plane being defined as a plane perpendicular to the axes of rotation of the mirrors, and considering the active face (2) as a straight segment in the work plane, which corresponds to the approximation to a straight line of the conformation real that has the active face (2), which is the face where the concentrated radiation (6) reflected by the mirrors (7), being said active face (2) perpendicular to the visual bisector (69) of the field of mirrors, said visual bisector (69) being that of the angle formed at the center point (3) of the active face (2) by the straight lines that go from said point (3) to the respective central points, (63) and (64), from the closest (5) and farthest (24) mirrors to the receiver (1); containing the receiver (1) elements interiors (19) that absorb solar radiation, being said receiver (1) of longitudinal geometry, and its greater parallel length to the longitudinal axes (14) of the mirrors; having one last mirror (24) which is the most away from the receiver, mounting mirror fields symmetrically with respect to two parallel receivers with the opposite active faces, looking at each face in a field, particularly in the assemblies in the which longitudinal axes follow the local meridian, and mounting both north and south of the receiver in cases where that the longitudinal axes of the mirrors are parallel to the parallel local astronomy, in whose assemblies two can also be located parallel receivers with opposite active faces, looking at each face a field; and the turn given to each of the mirrors (7), for its approach to the sun at each moment, it is defined because the normal (27) to the mirror (7) at its center point (25) coincides with the bisector of the angle formed, in the work plane, by the projection in that plane of the central ray (26) of the solar beam incident at that central point (25), and the straight line (48) that goes from this point (25) to the central point (3) of the active surface (2) of the receiver (1), already defined in that plane, the beam going (28) reflected from the center point (25) along the line (48); expressing positions and angles in a coordinate system in the work plane used, which is a plane perpendicular to the longitudinal axes, and therefore cuts transversely and perpendicular to the receiver and mirrors, projecting on said work plane the position of the sun according to astronomical data, and the ordinate axis of the coordinate system in the work plane being the vertical line (10) that passes through the central or middle point (3) of the segment representing the active face (2) of the receiver (1) in the work plane, and the abscissa axis (11) being the horizontal line that passes through the central point (63) of the mark that, in the work plane, represents the mirror (5) closest to the receiver (1), characterized in that each mirror (7) has as a straight section a parabolic arc profile that corresponds to the parabola that, passing by the central point (25) of the straight section of the mirror, which is the fixed point around which it revolves, the center point is focused (3) of the active face (2) of the receiver (1), and the axis of symmetry of the parable is the line that passes through this focus, it has a tilt over horizontal equal to that of sunrays (4) which are taken as rays of the reference position; and the straight section of the mirror is defined by the parabolic arch that is enclosed within the circumference (52) centered at the center point (25) of the mirror, whose radius is E / 2, E being the width of the mirror, which corresponds, for assemblies according to the meridian and for assemblies according to the parallel with the field of mirrors south of the receiver, in the northern hemisphere, to the value 2000 Dmax being the distance from the center point (64) of the last mirror (24) of the field, to the point center (3) of the active face (2) of the receiver (one); P being the quotient between the maximum drift of rays allowed in mirrors, and the value W, which is the width transverse visual or apparent of the active face (2) of the receiver (1), which is equal to the value of R multiplied by the cosine of angle A99 of the mirror in question; A99 being the angle formed by the normal to the active face (2) at its center point (3) and the straight (48) that joins this point with the central point (25) of the mirror; being A100 the angle formed by the normal to the active face (2) in its center point (3) and the line (66) that joins this point with the point central (64) of the furthest mirror (24); and Q being the mirror quality factor, which It is greater than 1 when the mirror is of good quality and its manufacturing tolerances do not introduce deformations significant in the reflection of rays; and less than 1 when enter, limiting in this invention its value between 0.5 and 2, and using the value of 1 as a basic reference; and being K a trigonometric coefficient, which depends on the sun's trajectory in the work plane and the geometric relationship between the receiver and the mirror, and that corresponds to 202 A55 being the position angle of the line (48) that joins the central point (25) of the mirror in question, with the center point (3) of the active face (2) of the receiver (1); and being A47b the situation angle of the sunrays (4) in the situation of effective ortho, moment from which the effect of the solar radiation on the receiver is considered relevant in the design of a specific device; and A47 being the angle of situation of solar rays that is taken as a reference.

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2. Concentrator of solar radiation, with independent multiple parabolic mirrors, according to claim one, characterized in that in the assemblies according to the parallel with the field of mirrors north of the receiver, in the Northern hemisphere, the value of the width E of the mirror corresponds to the lower of the two values set forth below, Eb and Ec:

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203

-

having P, Dmax, A99, A100 and Q identical meaning and characteristics as the same terms in the preceding claim, the values of the coefficients being trigonometric Kb and Kc

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204

-

where abs (value) means absolute value of the quantity that is inside the parenthesis, where A55 is the position angle of the line (48) that joins the central point (25) of the mirror in question, with the center point (3) of the active face (2) of the receiver (1); and being A47b (47b) the angle of central solar rays (4) of each beam, in the situation of effective ortho, moment from which effect of solar radiation on the receiver is considered relevant in the design of a specific device; and being A47c (47c) the angle of sunlight situation when the sun reaches its maximum height in the work plane.

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3. Solar radiation concentrator, with independent multiple parabolic mirrors, according to previous claims, characterized in that the reference situation or position of the solar rays is defined by the inclination with which the sun's rays strike (4, 26, 29, 32) on the horizontal (11), always expressed in the work plane, measuring this inclination, in the methodology to determine the parabolic profiles of the mirrors, by the angle formed by the sunrays of the reference position (42) with the vertical axis, which is the ordinate (10) of the system device coordinates; and alternatively measuring the inclination by the angle of situation (20) of the solar rays in relation to the axis of abscissa of the reference system associated to the work plane, counted levógiro from the positive semi-axis of abscissa (eleven); establishing itself as a prescription of the invention, for the assemblies of the device according to the meridian, a 90º value for this reference position angle, as the movement of the sun is always symmetrical in this plane in its daytime movement, and the sun is in the middle of its path in its apparent zenith, which is equivalent, with respect to the vertical axis, to a null angle, 0º; and for the assemblies according to the parallel, in the Northern hemisphere, with the field mirrors south of the receiver, the angle taken as reference position corresponds to the semi-sum of 90º with the maximum solar height angle, which is the sum of the complementary latitude of the place plus 23º 27 '; what equivalent to the angle of the reference sunrays, with respect to the vertical axis, be the complement of said semi-sum; and for assemblies according to the parallel, in the Northern Hemisphere, with the field mirrors north of the receiver, the situation angle which is taken as a reference has the value of the semi-sum of 90º sexagesimal with the maximum angle of maximum solar height, the latter being the sum of the complementary angle of latitude from the place plus 23º 27 '; which is equivalent to the angle of the rays reference solar, with respect to the vertical axis, be negative, and corresponds to the value 90º minus the semi-above mentioned, having the solar rays of negative slope reference in the system installation coordinates; given the symmetrical situation in the assemblies according to the parallel in the southern hemisphere.

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4. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that in the assemblies according to the parallel, with the mirrors south of the receiver, its reference solar position in the work plane is selected , which is reflected in a direction of the solar rays (4) that forms a given angle, A42 (42), with the vertical line of the place or axis of ordinates (10), positive and greater than zero sexagesimal degrees, and the parabolic profile of the mirror whose fixed central point (25) is located at the abscissa Xc and has a null order, and around which said mirror rotates, corresponds to 189 M being the slope of the axis of symmetry of the parable 190 and with A42 (42) being the cited angle, and X_ {0} being the abscissa of the apex of the parable, which corresponds in turn to 191 the coefficients C1, C2 and C3 being the terms following 192 and being Y_ {0} the ordinate of apex of the parable, which corresponds 193 and being its distance focal 194 and being the parabolic arc of mirror the section of the parabola contained within the circle (52) with center at the center point (25) of the mirror, and radius equal to half of the width E of said mirror.

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5. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that in the assemblies according to the parallel, with the mirrors north of the receiver, in the northern hemisphere, the value of the angle A42 ( 42) that form the solar rays of reference with the vertical line of the place or axis of ordinates (10) is negative and less than 0º, being the abscissa of the apex (37), X_ {0}, unconditionally positive, and the parabolic profile of the mirror whose fixed central point (25) is located in the abscissa Xc and has a null order, and around which said mirror rotates, corresponds to 195

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where A42 and M are common values for all mirrors, where M is the slope of the axis of symmetry of the parable 196 but not being common X_ {0} e Y_ {0}, which depend on the position of each mirror, these being coordinates 197 and the coefficients being characteristic of case 198 and being its distance focal 199 and being the parabolic arc of mirror the section of the parabola contained within the circle (52) with center at the center point (25) of the mirror, and radius equal to half of the width E of said mirror.

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6. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that in the assemblies according to the meridian, whose reference is that of the sun at the zenith, the angle A42 (42) that form the solar rays with the vertical of the place, is null, so the apex is on the same axis of ordinates in which the focus is, which is the central point (3) of the active face (2) of the receiver (1) , the apex abscissa, X_ {0}, being null; and the equation of the parabola in the general coordinate system (X, Y) is 200 being Y_ {0} the value 201 where H is the height of the point center (3) of the active face (2) of the receiver (1) in the system general coordinate, and Xc the abscissa of the central point (25) of the mirror in question; and applying this prescription also when the assembly is not according to the meridian, but the reference position it is that of the sun at the zenith in the work plane; and being the bow parabolic of the mirror the section of the parable contained within the circle (52) centered at the center point (25) of the mirror, and radius equal to half the width E of said mirror.

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7. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that each mirror is determined by its central point (25) and its width E, E / 2 being the turning radius around said central point, the extreme values of the parabolic arc of that mirror being determined by its polar coordinates, centered on the central point (25) of the mirror, and polar angle (A105) rotating counterclockwise from the axis of abscissa itself of each mirror (104), ending the mirror at each end at the points where it cuts to the circumference (52) centered on the center point (25) of the mirror and with radius (E / 2), whose polar coordinates are 205 being the coordinate angle polar A105 the value that solves the equation, 206 that as a transcendent equation is solve by numerical or graphic methods, and provide 2 values of angle A105, which in turn provide the values of coordinates of the extreme points; being 207 A42 being the angle formed by solar rays of the reference situation with the vertical of the place; and Xc and Ye being the coordinates of the center of the mirror; Y where X_ {0} and Y_ {0} are those of the apex of the parabola in question.

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8. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that the mirrors are placed in the solar field practically in contiguity, which means that, between two consecutive mirrors a value selected between 0.1% and 5% of the semi-sum of the widths of said mirrors. 9. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that the height of the central points (25) of the mirrors (7) is always the same in the basic or reference assemblies ; but the invention includes the variant that the heights of the central points (25) be different, in which case the axis of abscissa of the coordinate system with which the parabolic profile of each mirror is specified, is adapted to each mirror, and it is a horizontal line that passes through its central point (25), so neither the value of the abscissa of its center, Xc, nor the angle A42 varies, but the height H of the central point (3) of the active face (2) of the receiver, since it is expressed as height above the central point of the mirror in question, the result being subsequently transferred to the general coordinate system of the device, by mere translation of the abscissa axis; and adequately expressing in that system the geometric characteristics of each mirror (7). 10. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that, in the assemblies according to the parallel with the field of mirrors north of the receiver, in the Northern hemisphere, in which the height of the centers of the mirrors in the work plane, and therefore in local altitude, can increase as the mirrors move away from the receiver, giving the symmetrical situation, with respect to the equator, in the southern hemisphere, in which the increase of said height is applied to the fields south of the receiver, the separation between central points (76 and 78) of two consecutive mirrors (75 and 77) is specified based on the solar height angle A80 (80) by above which there is no optical interference between the mirrors, and depending on the angle A79 (79) formed on the horizontal by the line (90) that virtually joins the two aforementioned central points (76 and 78), as as a function of the respective width of both mirrors, denoted respectively by E and E ', and of the acute angle, on the horizontal, of the line that joins each central point of a mirror with the central point (3) of the active face (2) of the receiver (1), said angles being A84 (84) for the first mirror (75) and A82 (82) for the second (77), from which the respective inclination angles of the tangent to each mirror at its central point, the angle being A85 (85) for the first mirror and A83 (83) for the second, defined by 208 from which it remains specified the angle that forms the tangent to each mirror in its center point with the line (90) that virtually joins the points central (76 and 78), the angle A88 (88) being for the first mirror (75) and A86 (86) for the second (77), which correspond to 209 which in turn specifies the distance Z between the center points (76 and 78) of both mirrors measured on the line (90) that virtually joins them, being this value 210 which in turn sets the separation in coordinates of their central points, which are identified by the letter X and Y followed by the point number, being 211 applying this prescription of the invention from the mirror (5) closest to the receiver, to the most far (24).

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11. Solar radiation concentrator, with independent multiple parabolic mirrors according to any of the preceding claims, in which the widths E and E 'of two successive mirrors are known, as well as the angle A80 (80) of elevation of the sun above of which optical interference between mirrors is not allowed, the central point (76) of the first mirror being also known, with coordinates X7 and Y76, and its upper end point (101) with coordinates X101 and Y101, and the angle A79 being fixed ( 79) of elevation from the center of the first mirror to the center of the second, and the center point (3) of the active face (2) of the receiver (1) having zero abscissa and ordinate coordinates H, characterized in that the value of the distance Z that separates in a straight line the central points of a first and a second mirror, (76) and (78) respectively, is the value that voids the difference between the ordinate Y102 of the lower end of the second mirror and the ord enada of the straight line (81) through which the ray with angle A80 circulates on the horizontal, and that rubs above the first mirror and below the second, for the value of the abscissa X102 of the lower end of the second mirror, which it is determined by interpolating between the values of Z_ {n} and Z_ {n + 1} that give the last negative value and the first positive, respectively, of the indexed difference 212 in the that 213 being 214 Y being 215 where the value of Z_ {n} is indexed, and corresponds to 216 12. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that the receiver is positioned with an inclination of its active face (2) on the horizontal, given by the angle A98 (98) in which this angle A98 is valid 217

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where A67 (67) is the angle of location of the line (65) that joins the central point (63) of the mirror closest (5) to point (3) of the receiver, and A68 (68) is the angle of the straight line (66) that joins the central point (64) of the furthest mirror (24) with point (3) of the receiver, and where T it is a value that is selected between -20º and + 20º, according to the design of the application of the invention.

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13. Solar radiation concentrator, with independent multiple parabolic mirrors, according to any of the preceding claims, characterized in that it includes a variant in the prescription of the parabola approach on the receiver, in which the focus of the parabola is fixed on a point (106) beyond the central point (3) of the active face of the receiver, located on the same straight line (48) that joins the center of the mirror with the central point of the active surface of the receiver, setting the distance (107 ) between the central point of the active face and the focus as a fraction of the distance from the center of the mirror to the center of the active face of the receiver, said fraction being selected between 0 and 1, the basic prescription being that said distance (107 ) is proportional to the distance from the center of the mirror (25) to the center (3) of the active face of the receiver, in the same proportion as the maximum drift of rays reflected from the mirror with respect to the an chura of this one.