DE8531571U1 - Tracking drive for a solar collector - Google Patents

Description

'fiiestfiuysqn & yoi}

The invention relates to a tracking drive for tracking the | Sun movement pivotable about a pivot axis, a main radiation | level solar collector, with two auxiliary collectors each with | a heat absorbing element for a heat transfer medium, wherein the auxiliary collectors 1 on both sides of the containing the pivot axis

Main radiation level are arranged perpendicular to a defining Haupteinstrah- \ lung plane lying transverse plane, and the heat absorbing elements of the
Auxiliary collectors via a transition element for the heat transfer medium with- i are connected to each other, wherein the auxiliary collectors to track the sun £ movement about the pivot axis from a starting position with the
one side inclined transverse plane over a middle position with horizontal
lying transverse plane can be pivoted into an end position with the > transverse plane inclined to the other side and through the transition of heat transfer medium from one side
Heat absorption element to the other heat absorption. 7, eelement always independently
can be brought into a position of the same energy absorption and wherein the
Auxiliary collectors preferably assigned to the heat absorbing elements Auxiliary reflectors on the one hand for partial shielding, on the other hand
have for radiation compression.

In the known tracking drive from which the invention is based |

(DE-PS 33 03 000) and all other known tracking drives

(British Patent 1,553,359), the auxiliary panels symmetrically on both sides ■ "

th of the main radiation plane. The main radiation level |

is the plane that includes the swivel axis of the swiveling solar collector \ and when the solar collector is exactly aligned with the sun
also includes the imaginary connecting line from the sun to the pivot axis. Through the two auxiliary collectors of the tracking drive is a; defines a transverse plane running perpendicular to the main irradiation plane, f which preferably, although not necessarily, also contains the pivot axis. I. E. ₅ that the transverse plane can possibly also be above or below the pivot axis of the solar collector. Incidentally, the symmetrical arrangement of the auxiliary collectors means on both sides
the main irradiation level does not mean that it is necessarily mirror-symmetrical

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'Gesth [iyseh & vof> Röhr

must be arranged. For example, it is advantageous to use the auxiliary collectors to offset axially with respect to the pivot axis against the actual solar collector and against each other in order to shade a changing side to be avoided if the solar collector is not precisely aligned.

The previously explained known tracking drive for a solar collector has proven itself extremely well and is structurally optimally simple. There is a certain problem with this known tracking drive in that when the sun is very low, the "sensitivity sensitivity" is low, i.e. the pivoting movement is slower and more sluggish than when the sun is high. This in turn is due to the fact that with increasing angle of inclination defined by the auxiliary collectors The transverse plane compared to the horizontal is achieved by shifting a certain mass of heat transfer medium from one heat exchanger element to the other re heat exchanger element generated torque decreases. The following equation applies:

= 2 * r * g * A

r <\ · cos

Where M is the moment about the pivot axis, m is the mass of the heat transfer medium, r is the radial distance between the heat absorption elements of the auxiliary collectors and the pivot axis, Λ is the angle opposite the transverse plane the horizontal, i.e. 0 ° with a horizontal transverse plane and 90 ° with vertical transverse plane. One can see without further ado that the moment caused by a certain mass displacement increases with the inclination of the transverse f level decreases according to a cosine function.

The invention is now based on the object of the known tracking drive with regard to the "sensitivity" when the sun is low to improve.

The tracking drive according to the invention, in which the above-mentioned object is achieved, is characterized in that two equalizing collectors each with a heat absorption element for a heat transfer medium

I; ' "(pesthjjysQn & yorj Rofcir

can be seen that the compensation collectors are arranged in the main irradiation plane on both sides of the transverse plane and are connected to each other via a transition element for the heat transfer medium, that the compensation collectors always independently in a position of the same energy consumption through the transition of heat transfer medium from the heat absorption element of one compensation collector to the heat absorption element of the other compensation collector can be brought and that the heat absorbing element of the compensation collector arranged below the transverse plane between the initial position and the middle position and the heat absorbing element of the compensation collector arranged above the transverse plane between the middle position Tt,. and the end position is shielded from solar radiation on the side facing the end position. According to the invention, in addition to the pair of auxiliary collectors, a pair of compensation collectors arranged at right angles thereto is also provided. These equalizing collectors are arranged in such a way that a decrease in the torque generated by the auxiliary collectors is compensated for or even overcompensated for by an increase in the torque generated by the equalizing collectors. The following equation essentially applies to the equalization collectors:

The sum of the moments of auxiliary collectors and compensation collectors results If one simplifies the assumption that the radial distances of all heat absorbing elements from the pivot axis are the same, this leads to:

4M = 2- r g'idm (cosrt + are \).

It has also been assumed that the masses are shifted when there is a change the solar radiation at the auxiliary collectors on the one hand and the equalizing collectors on the other hand is the same. Both the requirement with regard to the radius as well as the requirement with regard to the displacement of mass is not mandatory, it only serves to simplify the calculation.

'Gesttfuysan & vöra Röhr

The above equation for the total torque of auxiliary collectors and compensating collectors shows that in the tracking drive according to the invention the total torque is always at least as large as the largest torque generated by the auxiliary collectors alone when the transverse plane is exactly horizontal. The expression in brackets "cosdl + sind-" increases from the value 1 at d. = 0 ° to the value \ fT = 1.4142 at λ. = 45 ° and then falls back to the value 1 at λ = 90 °. Thus the "Ansprechempfindr friendliness" is the erfindüngsgemäßen Nachführantriebs low sun § ■ keinsswe ⁿ s worse than high, the sun _is; whereby a maximum for the "sensitivity" ^ is reached for mean i-active positions of the sun.
'U

What is essential for the teaching of the invention is the shielding of the compensation «I collectors against solar radiation in the manner explained. Would be this

f.! not available, both equalizing collectors would also be open when not yes, the solar collector aligned with the sun always absorbs the same amount of energy to have. The inventive shielding of the compensation collectors against solar radiation is achieved that when the sun rises Compensation collector arranged below the transverse level on the in the direction of ascent front side is shielded against solar radiation, so that its energy absorption decreases when the sun rises, heat

¹ I carrier medium is transferred from the other compensation collector and one

Pivoting movement to track the sun is initiated. Corresponding Q must now when the sun is sinking, i.e. after passing the middle position the compensation collector arranged above the transverse plane against solar

t be shielded from radiation in order to achieve the opposite effect when the sun is setting.

There are now various possibilities for embodying the teaching of the invention and further training, which will only be explained in the following by way of example.

First of all, there are various ways of shielding the compensation collectors from solar radiation. Mechanically

:; ''Gesthüyseh& vöh Rohr

This is easy to achieve because the equalizing collectors are provided with correspondingly hinged radiation shields. If the middle position is exceeded, the radiation shielding of the below the transverse plane arranged compensation collector folded down, so that solar radiation is no longer shielded, essentially at the same time the radiation shielding of the compensation collector arranged above the transverse plane is folded up and thus against solar radiation effective. Since in the area of the middle position by the auxiliary collectors anyway the greatest moment is generated, the mechanical energy required to carry out these folding movements can easily be obtained from the auxiliary collectors be generated.

There is also the option of changing the shielding against solar radiation to be realized without mechanical radiation shields, for example by means of electrically controlled liquid crystal screens. There is also the possibility of providing two equalizing collectors arranged below and above the transverse plane and with fixed ones To provide radiation shields and to switch from one pair of equalization collectors to the other pair of equalization collectors when the central position is reached. These are only exemplary possibilities for constructive Realization of the basic concept according to the invention.

It has already been stated previously that the radial distance of the heat absorption elements of the compensation collectors from the pivot axis not necessarily equal and not necessarily equal to the radial distance between the heat absorbing elements the auxiliary collectors must be away from the pivot axis. Nevertheless, this is of course particularly simple and expedient in terms of construction.

Uti to avoid mutual shadowing are according to preferred teaching of the invention, the compensation collectors axially offset from one another and preferably also arranged to the auxiliary collectors. Finally, it is advisable to add the '^ ·. knead compensation collector axially seen behind or in front of one end of the ouiv / enk axis, if this

'GesthjjyseSi & yör> Roijr

«I ·« 14

Pivot axis is physically present as such. Then it is avoided that the pivot axis shadows the compensation collector arranged below the transverse plane.

In the following the invention is explained in more detail with reference to a drawing showing only one embodiment; it shows

1 in a schematic representation explaining the functional principle an embodiment of the tracking drive according to the invention,

FIG. 2 shows the tracking drive according to FIG. 1 in an end view at at the zenith standing sun and

3 shows the tracking drive according to FIG. 1 in a front view with the evening sun being low.

The tracking drive shown in Fig. 1 is used for tracking the movement of the sun about a pivot axis 1 pivotable, a main radiation plane I having solar collector 2. The solar collector 2 has in the embodiment shown here, a reflector mirror 3 and a heat absorbing element arranged in the focal area of the reflector mirror 3 4 in the form of a heat pipe. The reflector mirror 3 is parabolic designed as a cylinder mirror, in the focal line of which the heat absorbing element 4 is arranged more or less precisely. The reflector mirror 3 of the solar collector 2 can be pivoted about the pivot axis 1, while the heat absorbing element 4 remains essentially at rest. It is however, it is not mandatory that a reflector mirror be provided at all and that the element to be tracked is the reflector mirror. That too Heat absorption element, a possibly provided auxiliary mirror, a possibly provided Carriers for measuring elements etc. can or can by the tracking drive be tracked.

: ':'. " feestHuysen & ί / αή Rohr

As FIG. 1 shows, the tracking drive has two auxiliary collectors 5, each with a heat absorbing element 6 for a heat transfer medium, preferably a refrigerant. The auxiliary collectors 5 are arranged symmetrically on both sides of the main radiation plane I containing the pivot axis 1. However, this arrangement is not mirror-symmetrical, but the auxiliary collectors 5 are axially ei i with respect to the pivot axis

On the one hand, offset from one another and, on the other hand, offset from the reflector mirror 3. The auxiliary collectors 5 define a transverse plane II lying perpendicular to the main radiation plane I. The heat absorption elements 6 of the auxiliary collectors 5 are connected to one another via a transition element 7 for the heat transfer medium. Moreover, the pivot shaft 1 as a whole is located above the Nachführantriebs the \ () Heavy line so that even without external influences a stable equilibrium is present.

In general, the tracking drive according to the invention with the solar collector can be arranged in a protective cover in the form of a glass tube, the axi'l offset arrangement of the auxiliary collectors 5 opposite the reflector mirror 3 is of particular importance, since the overall diameter of the arrangement is kept as small as possible can. Stops are also provided for both directions of the pursuit movement.

To follow the movement of the sun, the auxiliary collectors 5 are around the Pivot axis 1 from an initial position A with a transverse plane II inclined to one side, namely to the right in FIG with horizontally lying transverse plane II can be pivoted into an end position C with transverse plane II inclined to the left in FIG. 2, namely to the other side. This pivoting movement is generated by the fact that through the transfer of heat

carrier medium from a heat absorbing element 6 to the other heat absorbing element 6 the auxiliary collectors 5 always independently in a position the same Energy absorption are brought. The heat absorption elements contribute to this 6 associated auxiliary reflectors 8, on the one hand to the partial Shielding, on the other hand, serve to condense radiation.

i. "Gesthljyseh & von Rohr

According to the invention, in addition to the auxiliary collectors 5, there are now two equalizing collectors 9, 10 are each provided with a heat absorbing element 11 for a heat transfer medium. The equalizing collectors 9, 10 are arranged in the main irradiation plane I and symmetrically to the pivot axis 1 on both sides of the transverse plane II. Im shown and preferred In the exemplary embodiment, the compensation collectors 9, 10 are even symmetrical arranged to the transverse plane II, since this transverse plane II includes the pivot axis I here. But that is not mandatory.

The equalizing collectors 9, 10 have their own transition element for the heat transfer medium connected to each other and by transition from Heat transfer medium from one compensation collector 9 to the other compensation collector 10 always independently in a position with the same energy consumption bringable.

Fig. 1 shows that the equalizing collectors 9, 10 of a special Shielding against solar radiation is required. It can be clearly seen that the heat absorbing element 11 of the below the transverse plane II arranged compensation collector 9 between the initial position A and the middle position B on the end position C facing side opposite Solar radiation is shielded, while the heat absorbing element 11 of the expansion tank 10 arranged above the transverse plane II is between the middle position B and the end position C on the end position C facing Side is shielded from direct sunlight.

In the illustrated and preferred embodiment are for implementation the shielding against solar radiation the equalizing collectors 9, provided with correspondingly foldable radiation shields 13, 14. Instead of the mechanically foldable radiation shields 13, 14 also liquid crystal radiation shields or other types of radiation shields be provided. As an alternative, it is also possible to provide two pairs of equalizing collectors, which are correspondingly

& from l

are equipped with fixed radiation shields, and when they are reached the middle position to switch from one pair to the other pair.

In the illustrated and preferred Ausführungsbeispiei of the invention is the radial distance between the heat absorbing elements 6, 11 of the auxiliary collectors 5 and the equalizing collectors 9, 10 of the pivot axis 1. The radial distance could easily be smaller in the case of the equalizing collectors than with the auxiliary collectors. In addition, the radial distance between the differential collectors does not necessarily have to be the same.

The embodiment shown in Fig. 1 clearly shows that after A preferred teaching of the invention, the equalizing collectors 9, 10, like the auxiliary collectors 5, are arranged axially offset from one another. The equalizing collectors 9, 10 are also axially offset with respect to the auxiliary collectors 5 arranged.

Finally, Fig. 1 clearly shows that the below the transverse plane II arranged compensation collector 9 is arranged behind or in front of one end of the pivot axis 1 viewed axially *

Beam in Fig. 2, the sun from the upper left guide drive on the inventive post-\, the left disposed in the figure, the heat receiving element 6 is shielded by the auxiliary reflector 8, so that there is hardly any ER * _f-heating takes place. The solar radiation hits the heat absorbing element 6 on the right in Fig. 2, and is reinforced by the mirrored ■: apply inner surface of the auxiliary reflector 8. The heat transfer medium present here - liquid refrigerant - evaporates and condenses in the colder,, opposite heat absorbing element 6 down. So it finds a mas- | senverlagerung instead of heat transfer medium in the left located in Fig. 2 '. "heat receiving element 6. The result is a pivoting movement in the counterclockwise direction in Fig. 2, which ceases as soon as the two heat receiving elements of the auxiliary collectors irradiated 6 5 uniformly.

ί i. * · GfcsthiuysGn &! Von Rohr

The previously explained pivoting movement is supported by the compensation collectors 9, 10 * While namely in the previously explained situation of the upper compensation collector 10 through the radiation shield 14 against solar radiation Is shielded and remains cool, is the heat absorbing element 11 of the lower compensation collector 9 because of the folded away radiation shield 13 fully exposed to sunlight. The liquid refrigerant present here evaporates and condenses in the colder heat absorbing element 11 of the upper compensation collector 9 down. AiSö finds a MäSSöfiveriäyöruriy from WäffiioträyöriTiödiuin in the Wäffneaufnähmeeiöment 11 of the upper compensation collector 10 instead, which also results in a counterclockwise pivoting movement. As soon as the top Equalizing collector 10 is precisely aligned with the sun, its heat absorbing element 11 is again fully exposed to solar radiation, the heat absorbing elements 11 of both equalizing collectors 9, 10 are irradiated evenly, the pivoting movement ceases.

Fig. 3 shows the position of the tracking drive when it is very low Sun, practically in the end position C, clearly. It is clearly recognizable here that because of the almost vertical transverse plane II, the displacement of the masses of heat transfer medium between the heat absorbing elements 6 of the auxiliary collectors 5 only have a very small influence on the Has pivoting movement. On the other hand, because of the large effective lever arm, the mass displacement of the heat transfer medium between the heat absorption elements 11 of the equalizing collectors 9, 10.

A possibly particularly simple one is not shown in the drawing Construction of the radiation shields in which the tracking drive is characterized in that the radiation shields are attached to their own mounted on the pivot axis pivotably mounted carriers and can be taken along by the respective compensation collector when it is pivoted are. The radiation shielding for the compensation collector lying below the transverse plane is due to its own weight, for example on the side of the compensation collector and follows its pivoting

öestfijjysejn & yoq Roljr

movement to the lowest point of the pivoting path, d. H. up to the horizontal Position of the transverse plane * The radiation shielding then no longer follows a further swiveling of the associated compensation collector * The one above Radiation shielding associated with the transverse plane arranged compensation collector is just so strongly spring-loaded that it is held in an upright position * This radiation shielding then be taken along by the compensation collector when pivoting further counterclockwise in Fig. 2 of the drawing.

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Claims (7)

&. yort Rofeir is saying: 1. Tracking drive for a solar collector which can be pivoted about a pivot axis to track the movement of the sun and has a main radiation plane, with two auxiliary collectors each with a heat absorbing element for a heat transfer medium, the auxiliary collectors being arranged on both sides of the main radiation plane containing the pivot axis, a transverse plane perpendicular to the main radiation plane define and the heat absorption elements of the auxiliary collectors are connected to one another via a transition element for the heat transfer medium, the auxiliary collectors for tracking the movement of the sun around the pivot axis from an initial position with a transverse plane inclined to one side via a central position with a horizontal transverse plane into an end position with an inclined plane to the other side Swiveling transverse plane and through ¹ ! Transfer of the heat transfer medium from one heat absorbing element to the other heat absorption element can always be brought automatically into a position of the same energy absorbtion and the auxiliary collectors preferably have auxiliary reflectors assigned to the heat absorbing elements on the one hand for partial shielding and on the other hand for condensing radiation, characterized in that two equalizing collectors (9, 10) each with a heat absorbing element (11) for a heat transfer medium are provided that the equalizing collectors (9, 10) () are arranged in the main irradiation plane (I) on both sides of the transverse plane (II) and connected to one another via a transition element (12) for the heat transfer medium are that the compensation collectors (9, 10) by transferring heat transfer medium from the heat absorption element (11) of one compensation collector (9 or 10) to the heat absorption element (11) of the other compensation collector (10 or 9) always independently in a position of the same energy can be absorbed and that the heat absorption element (11) of the compensation collector (9) arranged below the transverse plane (II) between the initial position (A) and the middle position (B) and the heat absorption element (11) of the compensation collector arranged above the transverse plane (II) ::. ' 'Gfesthliysäh & von Röhr ι · «4 tors (10) zv / ischen the middle position (B) and the end division (C) on the the end position (C) facing side is shielded against solar radiation. 2. Tracking drive according to claim 1, characterized in that the compensating collectors (9, 10) with correspondingly hinged radiation shields (13, 14) are provided. 3. Tracking drive according to claim 1 or 2, characterized in that the radial distance between the heat absorbing elements (6, 11) of the auxiliary collectors (5) and the compensating collectors (9, 10) from the pivot axis (1) is the same. 4. tracking drive according to claim 1 or 2, characterized in that the radial distance between the heat absorbing elements of the equalizing collectors from the pivot axis is smaller than the radial distance between the heat absorbing elements the auxiliary collectors from the pivot axis. 5. Tracking drive according to one of claims 1 to 4, characterized in that that the compensation collectors (9, 10) are arranged axially offset to one another and preferably also to the auxiliary collectors (5). 6. tracking drive according to one of claims 1 to 5, characterized in that that the compensation collector (9) arranged below the transverse plane (II) is arranged, viewed axially, behind or in front of one end of the pivot axis (1) is, 7. tracking drive according to one of claims 1 to 6, characterized in that that the radiation shields are attached to their own carriers mounted on the pivot axis and from the respective compensation collector can be taken along when pivoting.