U.S. patent application number 10/542609 was filed with the patent office on 2006-07-13 for solar collector.
Invention is credited to Erwin Hoelle, Klemens Jakob.
Application Number | 20060150967 10/542609 |
Document ID | / |
Family ID | 32747503 |
Filed Date | 2006-07-13 |
United States Patent
Application |
20060150967 |
Kind Code |
A1 |
Hoelle; Erwin ; et
al. |
July 13, 2006 |
Solar collector
Abstract
The invention relates to a solar collector for focusing solar
radiation onto a focal line, said solar collector comprising a
carrier for a grooved, arched reflector. According to the
invention, the carrier comprises a plurality of molded grooves
which each have a parabolic lateral edge; the molded grooves are
surrounded by an outer film; the reflector consists of an elastic
reflector material; and the form of the reflector is impressed on
the elastic reflector material, directly or by inserting a carrier,
by means of the parabolic lateral edge.
Inventors: |
Hoelle; Erwin; (Rosenfeld,
DE) ; Jakob; Klemens; (Isingen, DE) |
Correspondence
Address: |
DREISS, FUHLENDORF, STEIMLE & BECKER
POSTFACH 10 37 62
D-70032 STUTTGART
DE
|
Family ID: |
32747503 |
Appl. No.: |
10/542609 |
Filed: |
January 23, 2004 |
PCT Filed: |
January 23, 2004 |
PCT NO: |
PCT/EP04/00564 |
371 Date: |
July 18, 2005 |
Current U.S.
Class: |
126/694 |
Current CPC
Class: |
F24S 23/74 20180501;
F24S 30/425 20180501; F24S 23/82 20180501; Y02E 10/40 20130101;
Y02E 10/47 20130101; F24S 2030/14 20180501 |
Class at
Publication: |
126/694 |
International
Class: |
F24J 2/12 20060101
F24J002/12 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 24, 2003 |
DE |
103 03 476.5 |
Claims
1-11. (canceled)
12. A solar collector module to focus the sun's rays onto a focal
line, the module comprising: a support structure, said support
structure having a plurality of form ribs, each of said form ribs
having parabolic lateral edges; an outer skin, said outer skin
surrounding said support structure such that said form ribs are
clad in said outer skin; and a trough-shaped, arched reflector,
said reflector having a pliable reflector material and a shape
defined by said parabolic lateral edges of said form ribs.
13. The module of claim 12, wherein said reflector is disposed
directly on said outer skin.
14. The module of claim 12, further comprising a carrier disposed
between said outer skin and said reflector.
15. The module of claim 12, wherein said form ribs have a sickle
shape.
16. The module of claim 12, wherein said parabolic lateral edges of
said form ribs are established by folding or corrugating said form
ribs.
17. The module of claim 12, wherein an opposing side of said
parabolic lateral edges has a partially circular contour.
18. The module of claim 12, wherein said form ribs and said outer
skin constitute an enclosed rigid box structure.
19. The module of claim 12, further comprising a trapezoidal metal
sheet disposed between said reflector material and said outer skin
to seat on said parabolic lateral edges of said form ribs, said
metal sheet having longitudinal grooves running along said
trough-shaped reflector, wherein said reflector material seats on
said metal sheet.
20. The module of claim 19, wherein said grooves form channels,
structured to be sealed at ends thereof.
21. The module of claim 19, wherein said trapezoidal metal sheet
and said outer skin are attached to said form ribs.
22. The module of claim 21, wherein said metal sheet and said outer
skin are attached to said form ribs using screws, rivets, or
adhesive.
23. The module of claim 19, wherein said reflector material is
glued to said grooves of said trapezoidal metal sheet.
24. The module of claim 12, wherein said reflector material
comprises a metal, a plastic foil, or a thin glass layer, wherein
said foil has a reflective surface on its upper side and said glass
has a reflective surface on one or both sides.
25. The module of claim 24, wherein said foil or said glass layer
has a thickness on the order of 1 mm.
26. The module of claim 12, further comprising means for a
receiving tube disposed along the focal line and supported by
support arms, wherein said support arms are connected to said form
ribs and/or to an upper surface of said reflector.
Description
[0001] The present invention relates to a solar collecting module
characterized by the terms in claim 1.
[0002] Solar collectors of the above type use a parabolic shaped
reflecting surface to collect and focus sunlight onto a focal line.
The reflecting surface is moved along its horizontal axis to follow
the movement of the sun during the day.
[0003] These solar trough collectors have proved themselves over
many years and are manufactured with different mirror support
structures.
[0004] Modern solar collectors are up to 100 meters long and are
approximately 6 meters wide.
[0005] They are driven using one or more electric motors.
[0006] As is evident from the dimensions of these collectors and
the fact that they stand exposed to the weather they are subject to
high wind forces. These wind forces place high demands on the
collecting modules in relation to the stability of the mirror
support structures.
[0007] These forces are especially high in relation to the twisting
or torsional rigidity of the structure. The reflecting and
concentrating properties of the collectors are adversely affected
by even small deformation and this affects the efficiency of the
installation.
[0008] In order to provide enough resistance to these torsional
deformation forces reticular tube structures are used to support
the parabolic shaped mirrors. This uncoupling of support structure
and pre-formed reflectors results in an extremely complex overall
structure.
[0009] An example is the solar collector DE-A-198 01 078 which uses
such a reticular tube structure to support the reflector surface.
The support structure is connected to a carrier tube, which
provides the torsional rigidity. The reticular support, however,
does not contribute to the torsional strength, which means that
these constructions are still prone to torsional deformation.
[0010] Another example is the parabolic trough concentrator
DE-A-197 44 767 that likewise uses a reticular support
structure.
[0011] Diagonal tubes connected to the individual support arms
provide the torsional rigidity. This type of construction is
suitable solely for short collector modules as the torsional
rigidity is not optimal.
[0012] DE-A-199 52 276 presents a parabolic trough collector in
which swiveling support arms are arranged on a central axis. Here
also the torsional rigidity originates only from the central axis
tube. The arms themselves do not contribute to the torsional
strength.
[0013] WO-A-02 103 256 demonstrates a parabolic solar collector
which has a central tube onto which side arms are mounted. This
type of reflector is indeed relatively resistant to bending but has
almost no torsional rigidity.
[0014] The present invention is based on the task of building a
solar collector, which provides torsional rigidity in a simple
construction.
[0015] This task is resolved by a solar collector module having the
features of claim 1.
[0016] In the present invention forming ribs are surrounded by an
outer skin layer. Together these form an enclosed box construction,
which possesses very high torsional strength. In addition, the form
ribs are also parabolic shaped on their concave edge so that the
reflector material takes on the parabolic trough shape when
impressed upon the reflector. This means that the reflecting
surface material need not be rigid. Pre-formed parabolic mirrors,
which are relatively expensive, are not necessary. Instead, the
material can be pliable.
[0017] This pliable reflector material can, for example, be
delivered on a roll and then cut to the required size on site.
Transport costs are, in this way, considerably reduced and the
reflector surface material itself is also considerably cheaper than
pre-formed parabolic mirrors.
[0018] The present invention has the advantage of high torsion
strength and that, not only pre-formed parabolic mirrors, but also
pliable reflector material can be utilized because the parabolic
trough shape is impressed on the outer skin in the concave area of
the form ribs.
[0019] A further embodiment provides that the form ribs demonstrate
a sickle shape. Because of this sickle shape the whole support
structure with its outer skin has, essentially the form of a
supporting wing. This is, for example, familiar in aircraft or ship
construction and possesses high rigidity in regard to bending and
torsion factors.
[0020] In order to give the form ribs the desired shape in a simple
manner they are manufactured using a folding or rippling process so
that a concave lateral edge results that is essentially parabolic
shaped. At the same time the edge opposite the parabolic edge can
be arched.
[0021] Onto this closed, torsion rigid support construction, formed
by the form ribs and the outer skin the pliable reflector material
is applied so that it adopts the parabolic shape.
[0022] Preferably a trapezoidal metal sheet is laid onto the outer
skin, which lies on the parabolic lateral edge. This sheet has
grooves running lengthways along the curved trough shaped collector
onto which the reflector material is laid. This has the advantage
that the supporting surfaces of the reflector material, formed by
the grooves in the trapezoidal sheet, are free from obstructions,
for example, screw or rivet heads and that the grooves form
parallel running, strip surfaces which support the shape of the
reflector material. Thereby, too, compensation for materials with
different heat expansion coefficients, for example, glass reflector
materials and metal outer skin or support structure is
achieved.
[0023] The grooves of the trapezoidal metal sheet form channels
that are apt to be sealed at their lateral ends. These kind of
closed channels have the advantage that they can be evacuated so
that, when the pliable reflector surface material is placed onto
the support surfaces of the grooves with a layer of adhesive
between, the channels of the grooves can be evacuated and the
reflector material is held in place. This can be continued until
the adhesive layer has sufficiently hardened. By this means,
special clamping systems can be spared. Another possible method for
pressing the pliable reflector material in place is that, after
laying the reflector in place, the trough is closed at the lateral
ends and filled with water. Through the water pressure the
reflector material is pressed onto the grooves while the adhesive
hardens.
[0024] In an embodiment, the trapezoidal metal sheet is fixed,
together with the outer skin, to the form ribs using, for example,
screws or rivets. In this way, a separate riveting or screwing
process is avoided because the outer skin lies between the form
ribs and the grooves of the trapezoidal sheet and is held in place
by the fastening of the trapezoidal sheet to the form ribs.
[0025] As already mentioned, it is advantageous to glue the
reflector material to the grooves of the trapezoidal sheet. In this
way, small deformations in the surface of the reflector material
are avoided. Apart from this, different materials, as well as
glass, can easily be fixed to the trapezoidal sheet.
[0026] In this way, the reflector material used in the present
invention can be a metal or synthetic foil or a thin glass layer
with a thickness of, for example, 1 mm. The foil material having a
reflecting upper surface and the glass a reflecting surface on one
or both sides.
[0027] These thin materials have the special advantage that a
second or more layers can be added to them. In this way repair is
considerably simplified. Due to environmental effects the reflector
surfaces become gradually "blind" in that the reflecting properties
are adversely affected. They must then be either exchanged or the
mirror surface renewed. Whereas the present invention allows for
new layers of reflecting material to be added.
[0028] Along the focal line of the collector provision is made for
a receiving tube, which is supported by support arms. These are
attached to the form ribs and/or the upper surface of the reflector
(16).
[0029] This simple structure contributes to an inexpensive
construction of the present invention.
[0030] Further advantages, characteristics and details of the
present invention are contained in the following description in
which especially preferred embodiments are represented in detail
with reference to the drawings.
[0031] The characteristics represented in the drawings as well as
those mentioned in the description and/or the claims can relate
individually or in any combination to the present invention.
[0032] The drawings show:
[0033] FIG. 1 A perspective representation of a reflector
module.
[0034] FIG. 2 The support structure of a reflector module.
[0035] FIG. 3 Lateral view of a form rib in the direction of arrow
111 in FIG. 2.
[0036] FIG. 4 A blank cutting for form ribs.
[0037] FIG. 5a to 5c Details of production steps in the manufacture
of a form rib.
[0038] FIG. 6 An alternative drive for a reflector module installed
on a level base.
[0039] FIG. 1 shows a reflector module (10), a plurality of which
constitute a solar collector plant.
[0040] This reflector module (10) is fastened to a support
structure (not shown) and is arranged so that the incident sun's
rays strike the concave area (12) and from there are reflected onto
a receiving tube (14) (see FIG. 3). For this the concave area (12)
is formed from a parabolic shaped reflector.
[0041] The reflector module (10), as schematically represented in
FIG. 2, consists of a plurality of form ribs (18), which lay
parallel to each other. The form ribs (18) are clad on their
concave edge (12) and their convex edge (20) with an outer skin
(22) as represented in FIG. 1. The outer skin (22) is fixed to the
form ribs (18) by means of screws, rivets or some other means. In
this manner the form ribs (18) and the outer skin (22) form an
enclosed support structure.
[0042] In FIG. 3 rivets are schematically represented by means of
which the form ribs (18) and the lower section (26) of the outer
skin are fastened.
[0043] An upper section (28) of the outer skin (22) is laid onto
the concave edges (12) of the form ribs (18) and onto this upper
section (28) of the outer skin (22) a trapezoidal metal sheet (30)
is laid. The lower bridges (32) of the trapezoidal sheet (30)
together with the interposed upper section (28) of the outer skin
(22) are then riveted to the form ribs (18). The upper bridges (36)
of the trapezoidal sheet (30) now form the laying surface for a
reflector material (38), which is pliable and rests on the upper
bridges (36).
[0044] In this way the reflector material (38) adopts the
characteristic shape of the concave surface of the trapezoidal
sheet (30). This shape is the desired parabolic form, which allows
the incident sun's rays to be directed onto the receiving tube
(14). The reflector material (38), which can consist of a
reflecting metal or synthetic foil or a layer of thin glass mirror
having a thickness of, for example, 1 mm is then glued to the upper
bridges (36).
[0045] FIG. 3 shows, in addition, a support arm (40) apt to carry
the receiving tube (14). These arms are fastened by rivets or some
other means to the reflector (16) together with the upper bridges
(36) of the trapezoidal sheet (30) and or with the underlying form
ribs (18).
[0046] FIG. 4 shows a metal strip (ref. No 42) with a width of 1200
mm out of which alternating blanks (44) are cut each blank being
6000 mm long. These blanks (44) or (46) as shown in FIG. 5a are
further processed with a metal folding machine (not shown) in that
they are bent to form the concave area (12) contained in the
lateral edge (48). This is achieved by rippling (50) or folding.
The section thus formed still has an essentially angular outer form
that is chamfered in the next production stage by pressing or
folding. During this production stage the lateral edge (48) is cut
and or flanged so that, after laying the outer skin (22), the
trapezoidal sheet (30) and the reflector material (38) onto the
upper section (26), all have the desired parabolic shape.
[0047] In addition recesses (52) are introduced through which pipes
for liquids and electric power cables can run inside the reflector
module (10). The rivets are fastened through the flanged edges.
[0048] Altogether it can be see that the present invention
comprising a plurality of reflector modules (10) possesses the
considerable advantage that each reflector module (10) has the
required torsion rigidity and that pliable reflector material (38)
can be used onto which the parabolic shape is impressed by the
trapezoidal sheet (30) and the form ribs (18). It is therefore not
necessary to use expensive pre-formed rigid mirrors. Relatively
inexpensive foil materials can be utilized or thin glass mirror,
which are also less expensive.
[0049] The bonding bridges (54) connecting the upper bridges (36)
and the lower bridges (32) balance different heat expansion
coefficients between the reflector material (38) and the outer skin
(22) without problem. In this way heat stress factors do not build
up.
[0050] In an embodiment represented in FIG. 6 the reflector modules
(10) lie on a level base and can be swiveled by means of a suitable
drive. The lower section (26) of the outer skin (22) is provided
with a cogging, which engages, with another cogging or a pair of
cogwheels mounted on the base. This type of fixed reflector module
(1) is even more resistant to buckling than hanging modules. They
are also less exposed to the wind.
* * * * *