US20110180059A1

US20110180059A1 - Solar thermal energy system

Info

Publication number: US20110180059A1
Application number: US12/737,937
Authority: US
Inventors: Martin Selig; Max Mertins
Original assignee: Novatec Biosol AG
Current assignee: Novatec Solar GmbH
Priority date: 2008-09-03
Filing date: 2009-08-11
Publication date: 2011-07-28
Also published as: AU2009289895A1; EP2161516A1; TR201101890T1; WO2010025808A4; ZA201101141B; CN102144134A; WO2010025808A3; EP2161516B1; PT2161516E; AP2011005601A0; BRPI0918089A2; ES2374749T3; MX2011002019A; EP2330362A2; WO2010025808A2; ATE534002T1; EP2330362A3; MA32759B1

Abstract

In order to increase the efficiency of a solar thermal system, it is proposed that a measuring robot movable in the longitudinal extension, which can measure the radiance distribution directed at the receiver tube along the receiver and therefore can check if the reflectors of the system are correctly adjusted, be placed on the cover of the receiver, which is supported in a raised manner.

Description

The present invention relates to a solar thermal energy system having a plurality of reflectors, which reflect incident sunlight onto a receiver mounted in elevated manner, whereby the receiver has a receiver pipe that is overlapped by a receiver cover, and a measuring robot is disposed on the receiver cover for measuring the beam density distribution of the sunlight reflected by the reflectors in the area of the receiver pipe.
A solar thermal energy system essentially consists of an array of reflectors and a receiver pipe. The reflectors are directed into the incident sunlight in such a way that the sunlight is reflected by the reflectors and bundled onto the receiver. The receiver is a pipe that is surrounded by a translucent housing on its side facing away from the reflectors. A medium is conducted in the pipe, which medium is heated by the sunlight focused onto the pipe. Because of the temperatures resulting from this, energy can be obtained using a configuration of this type. Because an entire array of reflectors is used, which bundle the incident sunlight onto the receiver, it is necessary for these reflectors to always be oriented directly onto the receiver pipe. Particularly because the reflectors must be tracked to follow the path of the sun in order to achieve improved efficiency, precise setting and the most ideal possible optical conditions are necessary for the greatest possible efficiency of such a system.
In particular, it is problematic if—either due to imprecise orientation or due to imprecise tracking—the individual reflectors are not set optimally or if the receiver is dirtied and thus an optimum transmission of the light energy cannot be achieved. In the area of the receiver, which, among other things, has a cover that is also reflective on the inside, so that light guided past the receiver pipe is focused once again on the receiver pipe, the cleanliness of this mirror, on the one hand, but also the cleanliness of the glass pane enclosing the receiver pipe in the cover, through which the light from the reflectors falls onto the receiver pipe, on the other hand, are essentially important.
In this context, it is known to fasten a measuring robot onto a framework on a receiver, so that the robot can be moved on the framework, along the receiver, and thus can resolve the incidence of solar energy through the primary reflectors as a function of location. However, it is problematic in this connection that the measuring robot in question can always be used on only one receiver.
Therefore the present invention is based on the task of creating a solar thermal energy system that ensures a high degree of effectiveness and also otherwise overcomes the disadvantages of the prior art.
This is achieved by a solar thermal energy system according to the characteristics of the main claim as well as the other independent claims 6 and 15. Further practical embodiments of the solar thermal energy system can be derived from the dependent claims, in each instance.
According to the invention, a solar thermal energy system has a measuring robot that can be set up along the receiver pipe so that it can measure the radiation directed onto the receiver pipe. Such a measuring robot is particularly advantageously assigned to the receiver cover, on which the measuring robot can be disposed, without obstructing the beam path to the receiver pipe itself in this connection. In particular, the measuring robot is capable of detecting the incident radiation guided directly past the receiver pipe or the entire receiver, and thus determining whether and which of the reflectors are possibly set incorrectly. A corresponding measuring robot can also be used for the purpose of performing an initial adjustment of a newly set-up solar thermal energy system.
In operation, it is advantageous if the measuring robot, in each instance, can be moved on the receiver cover in its longitudinal expanse, in that the measuring robot is equipped with a chassis. A receiver cover usually has a polygonal shape, so that a defined travel surface is created for the measuring robot. Using lateral stoppers and guide elements, the measuring robot can be disposed on a receiver in such a way that it may be readily moved thereon. In particular, it is advisable if the measuring robot is shaped in such a way that it encloses the receiver with shape fit, to a great extent, so that the measuring robot is prevented from falling or rolling off the receiver. In this way, it is ensured that the measuring robot can also readily process multiple receivers, one after the other.
In detail, such a measuring robot has at least one measuring arm that is equipped with photocells. On the basis of the response of individual ones of the photocells on the measuring arm, the measuring robot can determine by how much a reflector of the receiver deviates as the target of the reflected incident sunlight. By means of a linear arrangement of the photocells on the measuring arm, a locally resolved distribution of the incident radiation on the receiver can be determined.
In a further embodiment, the measuring arm can be articulated onto the measuring robot so as to pivot, so that a more precise determination of the beams or the beam bundles guided past the receiver can take place. In addition, in this way the measuring arm can be laid against the measuring robot as needed, in order to be able to transport it in a compact transport form after use. If the measuring robot has pivoting measuring arms, the pivot position can be detected by the measuring robot, so that it can be taken into consideration during a calculation of the beam density distribution around the receiver. In order to perform a simultaneous measurement of the reflectors disposed on both sides of the receiver, it is easily possible to assign measuring arms to the measuring robot on both sides.
However, it is also possible in this context to pivot the at least one pivot arm underneath the receiver, so that the radiation incident on the receiver can be measured instead of the radiation conducted past the receiver.
Additionally or alternatively, another measuring robot, which is equipped with an inclination sensor, can be used on the primary collectors of the reflectors. This measuring robot detects the inclination of the reflector as a function of the location, in each instance, preferably using at least one inclination sensor. The deviation can then be determined by a reference value/actual value comparison and the orientation can be improved. This makes it possible to carry out orientation measurements, which were only executed as spot checks up to that time, in such a manner that they cover the area, and thus simplifies the adjustment procedure during the installation of a solar thermal energy system and its precision.
By means of the use of a suitable chassis, preferably consisting of a plurality of surface wheels for mounting the measuring robot on the reflector and a plurality of edge wheels for lateral guidance, the measuring robot can be moved automatically, to a great extent, on the reflectors, and also easily switch over from one reflector to the next reflector, which is adjacent in the longitudinal direction, by means of this construction, which is only set on.
In this connection, an adaptation of the shape of the measuring robot to the primary collector can also take place, so that automatic movement of the measuring robot along this collector, as well, is also possible, if applicable.
In this connection, means for adjustment of the primary reflector, in each instance, can also be assigned to the measuring robot, with which means a precise adjustment of the reflector with regard to the inclination can take place, if applicable also in sections.
It is entirely possible to provide a measuring robot that can be used both on the receiver and on the reflector and has one or more chassis suitable for this purpose. In this case, such a measuring robot has not only pivot arms having photocells, but also inclination sensors. This allows complete setting of the solar thermal energy system using only a single measuring robot.
In order to create a system that functions as independently as possible, it is practical if the measuring robot is remote-controlled, whereby it is particularly advisable if the measuring robot follows programming when performing its measurements, which programming permits it to process one receiver after another or one primary collector after another. In this connection, it is particularly practical if the measuring robot can be remote-controlled from a central computer or from corresponding electronic means, whereby the remote control takes place, to particular advantage, in wireless manner, in other words particularly by radio. A transmission of the measured values to the central computer also takes place by radio.
A second aspect, which can also readily be used independent of the measuring robots, to improve the efficiency of a solar thermal energy system, is the addition of controlled ventilation, which takes place by way of a separate fan. In order to ensure the cleanliness of the receiver, the receiver pipe is usually accommodated, in the area where reflectors deflect the sunlight onto the receiver pipe, in a cavity formed by the receiver cover, which cavity is closed off on the reflector side by a glass pane. In this way, it is ensured that the secondary reflector, which is also accommodated in the receiver, and the receiver pipe do not get dusty and their optical properties are not impaired. In addition, the glass pane that usually closes the cavity off in a downward direction is also somewhat protected from contamination in this way. However, the situation is such that the cavity formed in this way in the receiver is filled with a gas mixture, for example with air, and therefore also heats up and expands when the receiver is heated. Because this gas mixture is usually air, ventilation of the receiver will therefore take place when it is heated, while an inflow of air will occur during cooling. However, inflowing air can entrain dust into the cavity of the receiver, which can only be removed from there with great difficulty, and over time dirties the glass pane, the receiver pipe, and the secondary reflector. Therefore, it is provided according to the invention that the cavity is ventilated by way of a fan pipe, whereby an air filter, preferably a fine dust filter, is assigned to the fan pipe. In this way, no dust can penetrate into the interior of the cavity and dirty the glass pane or the receiver pipe.
In a practical further development, a blower can also be assigned to the fan pipe, which blower controls the air flow for ventilation.
The invention described above will be explained in greater detail in the following, on the basis of an exemplary embodiment.

The figures show:

FIG. 1 a solar thermal energy system in a schematic representation, which cuts through the receiver and the reflectors transversely,

FIG. 2 a measuring robot set onto the receiver, in a cross-sectional representation,

FIG. 3 the receiver, in a detail representation, having a fan having a fine dust filter, and

FIG. 4 a reflector having a measuring robot set on, in a perspective representation, at a slant from above.

FIG. 1 shows a solar thermal energy system 10, which essentially has an array of reflectors 11 and a receiver 20. The receiver 20 is disposed elevated above the reflectors 11. Incident sunlight 12 is bundled by the reflectors 11 and directed onto the receiver 20. The reflected sunlight 13 incident on the receiver 20 heats a receiver pipe 22 guided inside the receiver 20, in which pipe a medium is guided, and energy can be generated within the system by means of heating of the medium. In order to ensure that the reflectors 11 are aligned exactly with the receiver 20, a measuring robot 30 can be assigned to the solar thermal energy system 10, which robot checks the orientation of the automatically tracked reflectors 11 and can optimize the orientation, if necessary, on the basis of its measured values.
FIG. 2 shows a measuring robot 30 of this type, which is set onto a receiver 20. For this purpose, the measuring robot 30 has a recess 35, which is adapted, in terms of its shape, to the receiver 20. A specific spacing is maintained between measuring robot 30 and receiver 20 by means of a chassis 34, which is assigned to the measuring robot 30, in order to be able to move on the receiver 20 along its longitudinal expanse. The measuring robot 30 has a measuring arm 31, in each instance, on both sides, which arm is disposed on the measuring robot 30 so as to pivot, by way of a joint 32. Because of the joint 32, the measuring arm 31 can be brought into various angle positions relative to the measuring robot 30, so that the radiation deflected past the receiver 20, which is reflected by the reflectors 11, can be detected and measured in regard to the beam density distribution. Alternatively, the measuring arm 31 can also be pivoted between reflectors 11 and receiver 20, in order to detect the incident radiation on the receiver 20 instead of the radiation deflected past. Setting errors of the reflectors 11 can be found and remedied on the basis of the radiation conducted past the receiver 20. The efficiency of the overall configuration can be improved in this way. Such a measuring arm 31 is disposed on both sides of the measuring robot 30, so that a measurement of the reflectors 11 can be performed simultaneously on both sides of the receiver 20. In order to achieve the most compact construction possible for transport after removal of the measuring robot 30 from the receiver 20, the measuring arm 31 can be fixed in place on the sides of the measuring robot 30, in each instance, using a retainer 33. If the measuring robot 30 is set onto a receiver 20, the measuring robot 30 can be moved on the receiver cover 21 using the chassis 34. This can take place either by way of a remote control, for which purpose the measuring robot 30 has an antenna 36, however, it is also possible to equip the measuring robot 30 with programming, in such a way that it measures a receiver 20 completely automatically. In this connection, the data transmission takes place between the measuring robot 30 and a centrally set-up central computer, and is handled by way of the antenna 36, by radio.
FIG. 3 shows a further possibility for increasing the efficiency of a solar thermal energy system 1. For this purpose, it is provided to completely close off the cavity formed between the receiver cover 21 and a glass plate that closes off the receiver cover 21, so that no dust can penetrate. The cavity thereby filled with air heats up, however, due to the solar radiation that is conducted onto the receiver pipe 22 running inside the cavity, using the reflectors. The air expands due to the heating and escapes by way of correspondingly provided ventilation openings. During cooling of the receiver pipe 22 and thus also of the air inside the cavity, air is again drawn in, which may, however, carry dust particles into the interior of the receiver 20. For this purpose, a fan pipe 41 and a fan, in connection with a fine dust filter, not shown in any detail, are assigned to the cavity, so that, on the one hand, the inflow can be regulated precisely using the fan and, on the other hand, the air flowing into the cavity can be freed of dust. It is thereby ensured that the receiver 20, in particular the glass plate which closes off the receiver 20 toward the bottom, is not contaminated by the dust that is also drawn in.
During the measurement of the receiver, it is ascertained whether the light reflected by the reflectors onto the receiver is incident on the receiver, and how great the corresponding beam density is along the receiver and its immediate surroundings. However, for accurate incidence of the reflected light on the receiver, the inclination of the reflector must also correspond to the specifications. A measuring robot 50 according to FIG. 4 is therefore set onto a reflector 11 and equipped with an inclination sensor, so that the measuring robot 50 can determine the inclination of the reflector at any point of the reflector 11 along its longitudinal expanse. Simultaneously, it compares the measured values to the inclination predefined at the particular point, and can adapt the inclination of the reflector at the particular location, using suitable setting means. The current time is also taken into consideration in this connection, because the reflectors 11 are tracked according to the sun position, and therefore different degrees of inclination are necessary at different points in time. Because of the chassis 52 also provided here, which predetermines a defined position and travel direction, using edge wheels 54 and surface wheels 53, the measuring robot 50 can also be moved on the reflector 11. This construction, which is only set on, additionally allows adjacent reflectors in the longitudinal direction to be moved to continuously, by bridging a spacing, because fixation on a specific reflector 11 by means of corresponding structural measures, such as guide rails, etc., is not provided.
A solar thermal energy system is thus described above, which is made significantly more efficient in that setting of the system can be performed by means of a measuring robot, which can measure the incident sunlight conducted past the receiver and/or the inclination of the reflectors, and permits better and more precise setting of the reflectors with significantly reduced effort, by means of a comparison with the corresponding reference values. Furthermore, an improvement of the efficiency is possible in that the receiver is prevented from getting dusty, using a filter-supported ventilation system.
LIST OF REFERENCE NUMERALS
10 solar thermal energy system
11 reflector
12 incident sunlight
13 reflected sunlight
20 receiver
21 receiver cover
22 receiver pipe
30 measuring robot
31 measuring arm
32 joint
33 retainer
34 chassis
35 recess
36 antenna
40 fan connector
41 fan pipe
42 blower
50 measuring robot
51 primary collector
52 chassis
53 surface wheels
54 edge wheels

Claims

1-18. (canceled)

19. Solar thermal energy system having a plurality of reflectors (11), which reflect incident sunlight (12) onto a receiver (20) mounted in elevated manner, whereby the receiver (20) has a receiver pipe (22) that is overlapped by a receiver cover (21), and a measuring robot (30) is disposed on the receiver cover (21) for measuring the beam density distribution of the sunlight (13) reflected by the reflectors (11) in the area of the receiver pipe (22),

wherein the measuring robot (30) has a chassis (34) with which it is set onto the receiver cover (21), whereby the measuring robot (30) can be moved in the longitudinal direction of the receiver cover (21) by means of the chassis (34).

20. Solar thermal energy system according to claim 19, wherein at least one measuring arm (31), which has photocells for local resolution of the beam density distribution, is assigned to the measuring robot (30).

21. Solar thermal energy system according to claim 20, wherein the measuring arm (31) is articulated onto the measuring robot (30) so as to pivot, and the pivot position can be detected by the measuring robot (30).

22. Solar thermal energy system according to claim 21, wherein the measuring arm (31) can be pivoted into a position between receiver (20) and reflectors (11).

23. Solar thermal energy system according to claim 20, wherein at least one measuring arm (31) is assigned to the measuring robot (30), in each instance, on both sides.

24. Solar thermal energy system having a plurality of reflectors (11), which reflect incident sunlight (12) onto a receiver (20) mounted in elevated manner, whereby the reflectors (11), in each instance, have a primary collector (51) for reflecting the incident light onto the receiver (20), wherein a measuring robot (50) for detection of the inclination of the reflector (11) is disposed on the primary reflector (51), which robot can be moved on the reflectors (11) by means of a chassis (52).

25. Solar thermal energy system according to claim 24, wherein the chassis (52) is formed, in each instance, by means of a plurality of surface wheels (53) for mounting the measuring robot (50) on the primary collector (51), and edge wheels (54) for laterally guiding the measuring robot (50) in the longitudinal direction of the reflector (11).

26. Solar thermal energy system according to claim 24, wherein the measuring robot (50) has an inclination sensor for determining the inclination of a primary collector (51).

27. Solar thermal energy system according to claim 26, wherein the measuring robot (50) has means for adjustment, if necessary section by section, of the primary collector in regard to its inclination.

28. Solar thermal energy system according to claim 19, wherein the measuring robot (30, 50) at least partially encloses the receiver cover (21), or primary collector, with shape fit.

29. Solar thermal energy system according to claim 19, wherein the measuring robot (30, 50) can be moved in remote-controlled manner.

30. Solar thermal energy system according to claim 19, wherein the measuring robot (30, 50) is programmable for automatic execution of measuring series.

31. Solar thermal energy system according to claim 29, wherein data transmission takes place between a central computer for acquisition of data and, if applicable, remote control of the measuring robot, and the measuring robot (30, 50), preferably in wireless manner.

32. Solar thermal energy system according to claim 29, wherein an autonomous voltage source, preferably a rechargeable battery, is assigned to the measuring robot (30, 50).

33. Solar thermal energy system according to claim 19, wherein the measuring robot (30, 50) has means for detecting the relative longitudinal displacement on the receiver cover (21) or the primary collector (51).