NO20101606A1 - Absorbator, collector plate, collector plate system and method of making an absorber - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flow correction means for heat-carrying medium to be fed into a plurality of upstream channels in a collector plate. The invention also relates to a system of collector plates comprising flow correction agents.

Description

The area of technology

[0001] The present invention relates to an absorber, solar collector plate, system of

solar collector plates and method for producing an absorber.

[0002] It has struck me during the reading that we should probably emphasize the following aspects i

the patent requirements.

Background technology

[0003] A solar collector is a device that converts energy in solar radiation into heat at a usable temperature. Energy conversion takes place in an absorber. This is designed so that the radiation is absorbed and converted into thermal energy, and the energy is transferred to a heat-carrying medium, a fluid, which circulates inside the absorber and which transports it away from the solar collector plate's absorber and to a heat store, or for immediate use. The heat-carrying medium can be a gas, or a liquid, e.g. water. The solar collector plate is usually insulated, on the absorber side that faces the sun an insulation transparent to sunlight is usually used, e.g. glass or transparent plastic, and on the side of the plate facing away from the sun, mineral wool or other solid, temperature-resistant insulation is preferably used. A flat solar collector has a cover plate and preferably an absorber that is flat, i.e. there is no focusing of the sunlight towards the absorber. There are also flat solar collectors that do not have a cover plate in front of the absorber.

[0004] Solar collectors are traditionally built with aluminum and copper in the absorber material and with glass or plastic as a transparent cover plate. In absorbers built in aluminium, copper and copper alloys, glycol-containing water is often used as a heat-carrying medium to avoid frost damage. Alternatively, clean water can be used as a heat-carrying medium, but this must then be drained out of the solar collector if there is a risk of frost.

[0005] Pure water has about 30% greater heat capacity than water with added glycol in the necessary concentration, and is therefore more effective as a heat carrier in a solar collector.

[0006] Instead of metal, a solar collector absorber can be produced in plastic material. Plastic solar collectors are often used for pool heating, and therefore do not have a transparent cover glass. This limits the temperature the absorber will be able to reach when exposed to sunlight. Most plastic materials have limited durability in relation to exposure to sunlight and heat. The use of plastic in the absorber is primarily justified by the advantageous costs of mass production compared to metal absorbers. Production cost is a critical parameter, as the use of solar energy is primarily determined by whether it can prove price-competitive with the more conventional energy sources/carriers. Plastic materials that can meet the temperature requirements of a solar collector with a cover plate are, however, relatively expensive,

[0007] The present invention relates to a solar collector plate, an absorber

and manufacturing such an absorber for a planar solar collector.

[0008] In order to be able to utilize the heat that is deposited in a solar collector, the heat must be transported out of the solar collector and into a heat store or directly for consumption. For this, a fluid, called a heat-carrying medium or liquid, is used, which also circulates in the absorber of the solar collector. Filling the absorber with circulating fluid is necessary for heat transfer, as the plastic material has a very small heat conduction coefficient (I = 0.1 - 0.3 W/m degree). As the liquid comes into direct contact with the underside of the thin plastic surface where the energy in the radiation is deposited as heat, the necessary transport path for heat through the plastic material is minimised.

[0009] In conventional metal solar collectors, the heat-carrying liquid usually maintains a static overpressure (gauge pressure), typically 1-3 bar. Plastic materials are not suitable for a combination of high temperature and high pressure. The solar collector that the invention deals with therefore has a hydraulic system which is not put under pressure, but where the liquid flows out of the solar collector and back into a heat storage as soon as the supply of the fluid to the solar collector is stopped. The system is self-draining, and clean water can therefore be used without the addition of glycol, as a heat carrier.

[0010] Thermal stress during stagnation represents the biggest challenge for a plastic absorber in a solar collector. When no heat is drawn from the solar collector, and this is emptied of water, the temperature will rise to approx. 160°C (applies for example in Spain). There must be a material that can withstand the thermal doses at high temperature that normal use entails. There are so-called "high performance polymers" which appear to be a good candidate for absorbers, a special variant of PPS (Polyphenylene sulphide), appears to be particularly suitable for absorber plates. This material has excellent hydrolytic stability and temperature resistance. It retains its shape, stiffness and dimensional stability over time with large temperature variations. A problem with these so-called high performance polymers is that such polymers are difficult to process, for example by extrusion.

[0011] In order to produce an absorber in such polymer materials plate, an extruder tool (die) must be acquired. In order for the absorber plate to become as homogeneous as possible, all conditions that can introduce stress into the plate must be eliminated. This is particularly important in a solar collector absorber, as this, under the influence of sunlight, gets different temperatures on the two sides. Stress in the material means that polymers have different orientations in different parts of the surface, with associated free volume. When the plate is heated on one side, the stress will lead to a change in volume and consequently a change in shape, which causes permanent deformation of the plate.

[0012] Thus there is a need to produce a process for production

of absorber plates in so-called "high performance polymers".

[0013] In order to achieve optimal efficiency, it is crucial that the absorber plates have good contact between the absorber's heated surface and the heat-carrying medium, since desired polymer materials have little thermal conductivity. It is therefore necessary to ensure that the heat carrier fills the entire absorber volume, and that the circulation is approximately the same throughout the absorber. If not, the temperature of various parts of the absorber will be higher than necessary, with increased heat loss as a result. Experience has shown that approximately equal circulation for an entire absorber plate is a challenge.

[0014] Consequently, there is a desire to develop designs for absorber plates which ensure that the entire volume of the plates is filled with heat-carrying medium and that the circulation of heat-carrying medium is homogeneous for the absorber plate.

[0015] In many cases, a solar collector plate with an absorber plate will not cover a need for thermal energy, consequently there is a desire that several solar collectors can be connected together. One can think of two principles for connecting solar panels, either in series or in parallel. Series connection will ensure that all solar collectors have circulation, although not equal circulation internally in the individual absorber plate. However, series connection has a number of other disadvantages, the inlet temperature of the absorber plates will increase successively in the direction of flow of the heat-carrying medium. It does not provide optimal efficiency for the absorber plates that the inlet temperatures are additive in the direction of flow, furthermore it will of course present a challenge that absorbers that receive heat-carrying medium at a very high temperature will be exposed to extra stress.

[0016] By connecting the modules in parallel, all will receive water at the lowest temperature, which gives the best efficiency for the solar collector. However, it is a challenge to ensure that all solar panels in a parallel connected system have approximately the same circulation.

[0017] Consequently, there is a desire to provide a system for parallel connection of

solar collector plates that ensure good circulation through all solar collector plates.

Summary of the invention

The above-mentioned problems are solved according to the present invention by a device for solar collector plate for flow correction of heat-carrying medium to be fed into a plurality of upstream channels in a solar collector plate, where the device consists of one or more guide elements in a lower end channel adjacent to and opposite one or several supply openings covering part of the end channel cross-section.

[0018] According to one aspect of the device, this comprises a guide element arranged adjacent to a side surface of the end channel and adjacent to one or more upstream channels adjacent to the side surface of the collector plate.

[0019] In a further aspect, the guide element can be arranged adjacent to a side surface of the end channel and adjacent to one or more upstream channels adjacent to the side surface of the collector plate and on the opposite side of the downstream channel of the end channel.

[0020] The present invention also provides a device for a solar collector plate for flow correction of heat-carrying medium that is to circulate in a plurality of solar collector plates, where the device consists of at least one resistance element arranged in one or more downstream channels in the solar collector plate. According to one aspect, the at least one resistance element can be designed as a piece of pipe and where the piece of pipe has a minimum diameter that is smaller than the adjacent downstream channel.

[0021] Furthermore, according to the present invention, the at least one resistance element can be arranged in the smallest one downstream channel portion in the end channel. According to yet another aspect of the invention, the device can include a resistance element (49,r).

[0022] The present invention also provides a device for solar collector plate for flow correction of heat-carrying medium which is to be fed into one or more downstream channels in a solar collector plate, where the device consists of one or more guide elements in an upper end channel, where each of the at least one guide element is located adjacent to a downstream channel.

[0023] In a further aspect of the invention, the device comprises a guide element arranged adjacent to a downstream channel in the upper end channel.

[0024] According to the present invention, a solar collector plate is also provided for the circulation of a heat-carrying medium where the solar collector plate is designed with a first main part.

a) The first main part has the shape of a right-angled prism with rectangular end surfaces and two opposite rectangular side surfaces with

length d defining a cavity with an opening at two opposite ends, with an internal height h, an internal width b and a depth d, where d>b>h, the first main part further comprises several parallel upstream channels running parallel to the side faces, adjacent At least one of the side surfaces is arranged with at least one return channel that is parallel to it

the upstream channels.

b) Furthermore, the solar collector plate comprises an integrated inlet and outlet manifold with inlet and outlet channels which are parallel, the inlet channel is provided with at least one opening for the supply of heat-carrying medium to the first main part, the outlet channel is provided with at least one opening for receiving the heat-carrying medium from the return channel, the integrated outlet and inlet manifold is engaged with the lower open end of the first main part so that the heat-carrying medium from the inlet channel comes into communication with the parallel upstream channels, while the outlet channel comes into communication with the at least one return channel.

c) An upper end channel is arranged at the opposite open end of the first main part, the end channel comprises two other parallel side surfaces, a

back surface perpendicular to the two parallel other side surfaces, as well as two other planar congruent end surfaces so that the end channel when it engages with the first main part forms a closed volume for circulation of the

heat-carrying medium.

[0025] In one aspect of the present invention, the inlet manifold is provided with a chamber adjacent to said at least one opening, where the chamber is located between the inlet manifold's inlet channel and the first main part, adjacent to said at least one opening and in the chamber there is arranged at least a first restriction/ guide where the at least one first restriction/guide is arranged opposite or approximately opposite to the at least one first opening so that the heat-carrying medium has a velocity vector approximately perpendicular to the parallel channels.

[0026] In a further aspect according to the present invention, the solar collector plate is characterized by the fact that an imaginary rectilinear axis that extends parallel to the upstream channels and through the chamber will pass through a center line in the longitudinal direction of the inlet channel and the outlet channel and the parallel inlet and outlet channels are arranged adjacent

each other and so that one of the channels lies adjacent to the chamber.

[0027] In yet another aspect of the present invention, the outlet-inlet channel is provided with at least one pipe-like body in communication with the at least one return channel which leads heat-carrying medium out of the at least one return channel and through the inlet channel with a mouth into the outlet channel.

[0028] In yet another aspect of the present invention, the end channel is provided with at least one second restriction for the heat-carrying medium. Furthermore, the at least one other restriction (47) can be arranged adjacent to the at least one return channel.

[0029] Solar collector plate according to the present invention can be made in

a special variant of PPS.

[0030] According to the present invention, a solar collector module comprising at least one solar collector plate is also provided. The collector plate can be designed as indicated above. The solar collector module can include:

a) A first transparent cover plate.

b) At least one collector plate arranged below the first transparent one

the cover plate.

c) An insulation layer arranged adjacent to and below the at least one collector plate. d) At least two fastening profiles for fastening the first transparent cover plate, where one fastening profile is adapted for fastening to a

substrate.

[0031] According to one aspect of the present invention, the first fastening profile has a length approximately the length d of the solar collector plate, the first fastening profile is further provided with a protruding lip for engagement with a complementary lip arranged to the second fastening module, so that the first and other attachment modules are adapted to a "click connection".

[0032] In yet another aspect of the present invention, the solar collector module further comprises a top profile in engagement with the solar collector plate's upper end and the transparent cover plate's upper end, and a bottom profile in engagement with the solar collector plate's lower end and the transparent cover plate's lower end.

[0033] The present invention also provides a solar collector system comprising two or more solar collector modules, where the solar collector modules can be as indicated above the coupling in parallel arranged side by side where fluid communication between the modules is provided by manifold couplings, in each inlet channel and outlet channel it is detachable

provided a manifold coupling,

the two or more solar collector modules are further connected via the fixing devices.

[0034] Further advantages of the present invention will emerge from those

belonging to the patent claims.

Brief description of the figures

[0035] The present invention will be more easily understood with support in the accompanying

the figures there,

[0036] Figure 1 shows extrusion tools,

[0037] figure 2 shows an example of a plate with three absorber parts,

[0038] figure 3 shows an example of an embodiment of an absorber plate in cross section,

[0039] Figure 4 shows a solar collector plate according to an embodiment of the present invention

invention,

[0040] figure 5 shows a section of an absorber plate with inlet - outlet manifold,

[0041] Figure 6 shows a solar collector module in cross section,

[0042] Figure 7 shows a section of the attachment for two solar collector modules in cross section,

[0043] Figure 8 shows an example of the top and bottom profile of a solar collector module,

[0044] Figure 9 shows examples of manifold connections,

[0045] figure 10 shows flow of heat carrier in two parallel collector plates,

[0046] figure 11 shows flow conditions for parallel collector plates without

restrictions/guidelines,

[0047] Figure 12 shows flow conditions for parallel collector plates with

restrictions/guidelines,

[0048] Figure 13 shows the filling situation for three parallel solar collectors, and

[0049] Figure 14 shows the principle diagram for flow conditions for N parallel solar collectors.

Detailed description of invention

[0050] The present invention will now be described in more detail with support in the associated figures. The invention relates to a design of absorber plates which shall ensure an optimal filling and circulation of such, furthermore, the absorber plates are designed so that they can easily be included in a system of several parallel-connected solar collectors, where each solar collector comprises at least one absorber plate according to the present invention. Furthermore, examples of the production of absorber plates according to the present invention are shown.

[0051] It should be understood that in the following description, absorber or absorber plate will be used for elements where heat radiation is absorbed and converted into thermal energy, and the energy is transferred to a heat-carrying medium that circulates inside the absorber plate.

[0052] Solar collector plate is to be understood as a building element that comprises at least one absorber plate, insulation against a substrate and, in one embodiment, a transparent cover plate as well as fastening profiles that hold together the parts in the solar collector plate and which provide an attachment option to a substrate.

[0053] By a solar collector system is to be understood a system comprising several solar collector plates where the heat-carrying medium according to the present invention is connected in parallel.

[0054] According to the present invention, the heat-carrying medium can

be water, but other fluids can also be used.

[0055] In the following text, "high performance polymers", polymer, PPS or a "special variant of PPS" will be used interchangeably for the material in which the absorber plate according to the present invention is made. It should be understood that when it comes to the basic solutions related to the circulation and distribution of heat-carrying medium in an absorber plate or in a solar collector system, one or more parts can be made of other suitable material. As indicated at the beginning, absorber plates can be manufactured in a number of materials, and where the description is not material-specific, all such known materials for absorber plates can be covered by the terms "high performance polymers", PPS or a "special variant of PPS". However, it has been a desire of the patent applicant to produce a good extrusion process for a special variant of PPS (Polyphenylene sulphide), thus the production process itself will often refer to PPS.

[0056] According to the invention, a system of absorbers in plastic materials is thus provided, this necessitates, according to the invention, that the system operates under limited pressure. Thus, according to one aspect of the invention, one will have a self-drainage which means that all water must be able to run out of the absorbers as a result of gravity. This means that there are no "water locks" of any kind, in contrast to e.g. metal solar collectors, where the piping for heat carriers often runs in loops.

[0057] The drainage occurs when supply of the heat-carrying medium is stopped by air/steam coming up from a heat storage through the return pipe or return pipes from the solar collector to the heat storage. The air goes up into the return channel(s) in the absorber plate and the water flows out through a supply pipe for heat carrier to the absorber. When this has been emptied, the residual water from the lower manifold pipe flows out through at least one return pipe and back to the heat storage.

[0058] In what follows, a description will first be given of the production of absorber plates with associated inlet and outlet channels for the heat-carrying medium designed in a polymer, then the produced absorber plate will be described, and finally solar collector plates and

entire solar collector systems are given attention.

Production of absorber plates

[0059] If it is practically possible, an extrusion process will be suitable for producing the main part of absorber plates, i.e. the part where the heat transfer to the heat-carrying medium takes place, as this part usually forms a flat elongated body with a thickness of less than 5 cm which is hollow and often also provided with longitudinal internal channels. Two significant advantages of the extrusion process compared to other manufacturing processes are its ability to create very complicated cross-sections and work with very fragile materials because the materials are only exposed to compression and shear stresses. The extrusion process will also be able to produce parts with a very good surface finish.

[0060] Such a body will not be able to be molded in a single process which will

lead to a complicated compilation process afterwards.

[0061] Consequently, the patent applicant has put in the effort to try to develop an extrusion process for suitable polymer materials having a desired design. Extruded channel plates in PPS with dimensions that are necessary in a solar collector have never before been produced. The patent applicant, in collaboration with others, has succeeded in producing plates by extrusion, based on a design developed by the patent applicant.

[0062] To produce such a plate, an extruder tool 10 (die) must be acquired. In order for the plate to become as homogeneous as possible, all conditions that can introduce stress into the plate must be eliminated. This is particularly important in a solar collector absorber, as this, under the influence of sunlight, gets different temperatures on the two sides. Stress in the material means that polymers have different orientations in different parts of the surface, with associated free volume. When the plate is heated on one side, the stress will lead to a change in volume and consequently a change in shape, which causes permanent deformation of the plate.

[0063] The design of the extrusion tool therefore becomes critical.

[0064] The patent applicant has developed an extrusion tool, shown in figure 1, which eliminates the so-called "necking" effects in the outermost zones of the plate which are the main cause of stress in the plate.

[0065] The extrusion tool comprises a nozzle (die) 10, with an entrance 11 for feeding material such as PPS. The material is then fed out from the nozzle 10 via a narrowed part 12 which eliminates the aforementioned necking effects, further the material is led through a calibrator 13. Adjacent to the output of the calibrator 13 are arranged four knives 14, all arranged parallel to the direction of movement of the material being fed out of the calibrator. In one embodiment, two knives are arranged so that they cut off the edges of the discharged material, while the last two knives 14 are arranged so that the distance between adjacent knives 14 is the same. This results in three identical absorber plates being formed simultaneously in parallel. If the production of absorber plates with different widths is desired, it will of course be possible to change the mutual distance between the knives 14, but according to one embodiment, the mutual distance between the knives is adapted to building standards so that, as mentioned, one gets three identical absorber plates. According to one embodiment, the absorber plates are not symmetrical about a center point along the horizontal axis, the width axis, consequently the distance between the knives 14 cannot be easily changed.

[0066] Extensive tests have been carried out on the absorber plates to ensure that they withstand the temperature loads in a solar collector. The tests are based on accelerated aging at temperatures between 150°C and 200°C, and simulations of weather data from different climate zones show that the lifetime of the plates

as a result of temperature stress, the minimum is 20 years even in the south of Spain. Design of absorber plate according to an embodiment

[0067] The efficiency of a solar collector, i.e. how large a proportion of the radiation that hits the solar collector is converted into usable heat, is given by the following approximate formula:

[0068] where: r\ o is the efficiency when Tabs= Tamb,

Ki is effective heat loss coefficient,

K2 is effective heat loss coefficient, and

I is the solar intensity.

[0069] r|o is determined by the transmission through the transparent cover plate, the absorbance of the surface of the absorber and by

the heat transfer efficiency between the absorber and the circulating heat carrier. The heat loss to the surroundings is of decisive importance for efficiency at high working temperatures and/or low solar intensity.

[0070] Since polymer materials have low thermal conductivity, it is necessary to ensure that the heat carrier fills the entire absorber volume, and that the circulation is approximately the same throughout the absorber and in the various interconnected modules, otherwise the temperature of various parts of the absorber will be higher than necessary, with increased heat loss as a result.

[0071] In order to achieve an approximately homogeneous flow through the individual absorber, the dimensions must be chosen carefully. Furthermore, it is desired that the internal volume in the absorber plate be minimized so that the amount of heat carrier in the absorber plate is as small as possible. Optimum efficiency is thus ensured, with minimal release of heat to the surroundings and maximum heat transfer to the heat-carrying medium.

[0072] It is further desired that an absorber plate should be an integral part of a solar collector plate where the solar collector plate in turn constitutes one of several such solar collector plates in a solar collector system. It is therefore desirable that solar collector plates can be connected together, and of course that such connection is as simple as possible.

[0073] Furthermore, it is desired that the solar collector should be designed as a modular building element well adapted to the working methods used in the construction industry. It must be flexible in shape and dimension so that it can be used/fill in the area available on a building, and the solar collector's connections or manifold system must be designed so that it can be integrated within the building height (panel thickness) that the solar collector otherwise requires.

[0074] An ordinary absorber plate comprises a number of parallel channels, in one embodiment it is comprised of a significantly greater number of upstream channels than downstream channels. In yet another variant, an absorber plate with a single downstream channel/return channel is specified. The heat-carrying medium is fed in at a lower end of the absorber plate and directed upstream through the channels to then return through the downstream channels or the downstream channel for utilization.

[0075] The guidelines above suggest that there is a desire for a thin-walled and thin (small h) absorber plate with a width b adapted to building standards. Building elements are often adapted to such standards by being given a standard width or a multiple of a standard width. The height or length d is not as critical in a building context. As indicated above, an absorber plate comprises a main part, i.e. the part that is suitable for extrusion, this part will, with support in the guides above, be provided with a large number of upstream channels, and a small number of downstream channels/return channels and have a small internal thickness. According to one embodiment, the main parts are designed as indicated in Figures 2 and 3. Figure 2 shows a cross-section of three side-by-side absorber plates 20 as they appear during parallel production of three absorber plate widths before trimming, the channels can be seen in cross-section. Figure 3 shows a section of a cross section for an absorber plate according to one embodiment, or rather the main part 30 of an absorber plate. The main part 30 can be described by the following parameters:

n: number of parallel upstream channels 31,

m: number of downstream channels/return channels 32, in figure 3 limited to one, b: width for a main part,

b?. internal width of a downstream channel/return channel according to fig 3, b3: center to center channel width for upstream channels 31,

c: the width of three parallel produced main parts according to figure 2,

d: indicates the height or length of the main part, i.e. the channel lengths,

h: internal height, i.e. distance between internal surfaces, hte: thickness of the main part 30 of an absorber plate,

ti: the wall thickness for walls surrounding the downstream channel 32, as well as all external walls, and

t2: the wall thickness between channels.

[0076] In an embodiment adapted to a given building standard, the above-mentioned parameters for a main part 30 of an absorber plate according to an embodiment can be numbered as: n=55, m=1, b=560mm, b2=7mm, b3=10mm, c =1800mm, h=4.2mm, h2=6mm, ti=0.9mm and t2=0.4mm. The thickness of the main part is, as indicated, according to an embodiment h2=6mm, which is the smallest thickness of a channel plate that can be produced in the specially adapted PPS with the extrusion tool shown in Figure 1. The internal open volume is thereby approx. 3.6 litres/m<2>gross collector area. Incidentally, a 6mm thickness is a very common thickness for building elements adapted to the standard indicated above.

[0077] The main part 30 of an absorber plate must engage with a system for supply and return of heat-carrying medium so that a complete absorber plate for a solar collector system with a circulating heat carrier is provided. In the following, an example of such systems for supply and return of the heat-carrying medium is described.

[0078] To achieve a compact absorber, the main part 40,50 (ref. Figures 4 and 5) can be equipped with end channels 43,53,48 and a manifold for circulation of heat carrier (water) can be connected. Figure 5 shows an example of how end channels 43,53,48 with integrated manifold 51,52,55 can be attached 57 to the main part 40,50. The result has been achieved by developing a welding technique that makes it possible to create a tight connection between the molded end channel 43,53 and the extruded main part 40,50. Due to different manufacturing processes, these components may consist of slightly different types of material. The material in the end channels can typically have a low viscosity in the molten state, and glass fiber has been added, while the material in the extruded plates can have a significantly higher viscosity in molten form.

[0079] The welding can be carried out by so-called "hot plate welding" where the viscosities are corrected by the heating plates maintaining different temperatures towards the end channels and towards the extruded plates. Alternatively, this can be done by using infrared melting, also with different temperatures on the melted material. The welding process is particularly demanding because the dimensions of the walls that are welded together are so small.

[0080] Lower end channel 53,43 has, as mentioned, an integrated manifold 51,52,55. In this example, the upper manifold pipe 51 is for the supply of heat carrier. The heat carrier is introduced into the end channel 43,53 in an opening 55 at the bottom left of Figure 5. The end channel 43,53 distributes the heat carrier on the altogether n parallel channels in the longitudinal direction of the plate 40,50. When the heat carrier reaches the top, it is collected in an upper end channel 48 and led down and back to the return manifold pipe through a reinforced plate channel on the right side (fig 4). The reinforced return channel is shown on the right-hand side, but it is of course possible to turn the absorber plate so that the return channel lies on a left-hand side, thus the opening 55 also lies on the right. Furthermore, the indication of a single return duct and its positioning adjacent three outer walls is only an example of an embodiment. Advantageous is m<n, but it is not an absolute requirement that only one return channel should be used and that this should be arranged as indicated here. One can imagine a multitude of configurations for the upstream and downstream channel. Furthermore, one can imagine that one or more openings 55 can be experimented with and that their shape and size can be experimented with.

[0081] An internal wall in the lower end channel 43,53 is welded together with the left wall in the return channel in the plate 40,50 so that this is separated from the rest of the volume. A specially shaped pipe 49 ensures that the return water passes the upper manifold pipe 51 and is delivered to the lower return pipe 52.

[0082] The end channels 43,53,48 are welded to the main part 40,50. With the stated dimensions of main part 30,40,50 and end channel 43,53,48, and with the small wall thickness, the welding process will be complicated.

[0083] It should be understood that supply channels/pipes and return channels/pipes can change place, or shape. Furthermore, the supply opening 55 and the return pipe 49 can change place or shape, and if m>1 the number of return pipes 49 will have to be increased. A solution is shown where the inlet and return manifold are integrated in one piece for engagement with a lower end of the main part 40,50, a special solution could be that the return channel 52 is arranged at an upper end of the main part 40,50.

[0084] The chosen design, where the end channels and manifold are integrated into the absorber itself, gives dimensional limitations which result in pure laminar flow not being achieved in parts of the flow path. So-called jet streams will appear in parts of the system so that linear momentum becomes important for the pressure conditions. The jet streams have a specific range which is shorter than the length of the end channel 43,53. Therefore, in the lower end channel 43,53 in an embodiment as indicated by Figure 4 or 5, there will be very different flow conditions on the left and right side of this channel 43,53. The arrows in Figures 4 and 5 indicate the direction of flow for the heat-carrying medium. It can be seen that the velocity vector for the heat-carrying medium at the lower inlet channel is perpendicular to the longitudinal direction of the upstream channels, this is not accidental. As indicated earlier, it is desired that the upstream channels should have the most homogeneous flow distribution possible. If the velocity vector had been parallel to the upstream channels and the heat-carrying medium was introduced through an opening 55 as indicated in figure 5, then a favorable flow/filling distribution of the heat-carrying medium in the upstream channels would not have been achieved. Thus, to counteract the effect of the non-laminar effects, guides/restrictions 46,56,47 are introduced in the end channels 43,53,48. At the opening 55 in the lower end channel 53, a stopper/restriction 46, 56 is placed adjacent to and opposite the opening 55, which covers part of the cross section of the end channel 53, and ensures that the initial velocity component parallel to the upstream channels is broken and reflected so that a dominant horizontal velocity vector with little divergence. The design of the restriction is a design issue and can be subject to experimentation, thus the execution as shown is only an example that has proven beneficial for the configuration indicated by Figures 4 and 5.

[0085] According to an illustrated embodiment, the velocity vector in the lower end channel 43,53 is directed to the right, and the outlet channel with opening in the upper end channel 48 is on the right side. Therefore, a skewed distribution of the flow through the absorber plate's upstream channels with the largest volume flow on the right side will be natural both from the perspective of energy and impulse arguments. To correct for this, guides can be installed in the upper end channel 48 so that parts of the water flow up the right side of the absorber's main part 40,50 are directed to the left, i.e. against the dominant direction of velocity in the upper end channel 48. The guide can be given different designs, but the purpose is to ensure that the proportion of the flow in the upper end channel from the upstream channels on the right side of the absorber plate 40,50 is limited for the oppositely directed velocity vector. The design must also be made so that the mechanism works satisfactorily at different flow rates.

[0086] Figure 4 shows a restriction 47 arranged in the upper end channel 48, the restriction/guide has the form of an inclined partition with its base adjacent to the return channel. The restriction 47 has proven favorable for the flow conditions in the upper end channel 48, as the heat carrier that comes up in the right and left of the system is mirrored, the channels are forced to move against the current for a distance in the end channel before the flow reverses and is directed towards the outlet channel. Without this device 47, a disproportionately large part of the water flow will occur in the higher part of the absorber. The effects are shown on the IR images in figures 11 and 12.

[0087] Figures 11 and 12 show infrared photograding of three absorbers. Hot water is first circulated (light colour) and then cold water (dark colour) is introduced. Thereby, the velocity distribution of the water can be studied for the various channels in the absorber plates. At the top, the cold front is shown without the guide near the outlet in the upper end channel. The picture at the bottom shows the cold front with the guide installed. The flow distribution in the lower image provides acceptable cooling and consequently a high degree of efficiency, while the velocity distribution at the top is not acceptable.

[0088] If configurations other than the one shown in Figure 4 are used then will

other solutions for restrictions 47 could be imagined.

[0089] The flow velocity vertically in the upstream channels in plate 40,50 is very slow, of the order of 1-2 cm/s, and therefore no

pressure regulation mechanism due to different flow resistance. Solar collector plate according to an embodiment of the invention

[0090] As indicated, the absorber plate must be adapted to an environment in a context, thus the absorber must be supplied with other elements so that a solar collector plate is obtained. Figure 7 shows an example of a solar collector plate. The width of the absorber 60 is chosen according to one design so that when this is assembled with aluminum profiles 63, 64 and covered with a transparent cover plate 62 (for example in polycarbonate), the construction width of the solar collector module will be 60 cm, which is a general construction standard.

[0091] A separate fastening system has been developed as shown in Figures 7, 8 and 9. Solar collector system according to an embodiment of the present invention

[0092] A solar collector system consists of several modules or solar collector plates. These are placed side by side and fixed as shown in figures 7-9. The manifolds can be connected together with couplings 90 as shown in Figure 9. The couplings 90 are pipe connectors which, according to one aspect of the invention, are provided with at least one o-ring seal for each end connector which must engage with the upper 51 or lower 52 manifold pipe.

[0093] The circulation of heat carrier in a solar collector system consisting of two modules is shown in figure 10. By connecting the modules in parallel, all will receive water at the lowest temperature, which gives the best efficiency for the solar collector.

[0094] The solar collector is connected to a non-pressurized heat reservoir. The heat-carrying medium is transported from the heat storage to one or more solar collectors where the fluid via the inlet manifold 101 and the lower end channel pushes the air that is initially located in the absorbers down into the heat storage. When the circulation is stopped, air will flow up from the heat storage and the water in the solar collector and connection pipes 101, 102 will flow back to the heat storage.

[0095] It must be ensured that the circulation through all the absorbers in a parallel-connected solar collector system is approximately the same. When several modules are connected to the same manifold, during start-up there will be approximately homogeneous conditions due to the leveling effect of gravity. This is shown in Figure 13. As soon as the water reaches the upper end channel 48,108 and begins to flow back into the return channel, the static pressure will drop because the return channel fills. Since all the modules have the same pressure in the lower end channel 43,53, any delayed filling of a module could cause it to never be filled completely and remain passive.

[0096] According to the present invention, a method is provided to ensure that all solar collector modules have circulation, Figure 14 shows a schematic model of N solar collector modules mounted on the same manifold.

[0097] To ensure that all absorbers participate, a flow resistance 49,r is introduced at the bottom of the return channel in each individual absorber. The flow resistance is provided by a piece of pipe with a small internal diameter. The pressure drop across the resistance 49,r can be expressed to first order by

[0098] where v is the volume flow through the solar collector module and r is a resistance coefficient determined by the resistance's dimension, geometry, roughness and material.

[0099] Total volume flow through all solar collector modules is V. If N modules have circulation, the volume flow in each module will be V/N as we assume that all modules are identical and that the pressure drop in the manifold pipes is negligible.

[00100] To lift the heat carrier fluid to the top of the solar collector module a pressure of minimum

[00101] where H is the height of the solar collector module above the inlet pipe in the manifold, p is the density of the liquid and g is the acceleration of gravity.

[00102] When at least one of the modules is filled, the pressure difference between inlet and outlet, Pinn - Put, will be reduced to Ap since the return channel in the solar collector module is now filled with heat carrier.

[00103] If all the solar collector modules are to have circulation, r must be chosen so that

[00104] The resistance r thus depends both on the number of modules and on the total volume flow in the solar collector. According to one embodiment, the resistance is provided by a 5 cm long piece of pipe with a small internal diameter, it should be understood from the expressions above that r can assume different values, i.e. the length, internal diameter, and surface condition of the pipe piece can be varied, among other things, according to the number of solar collector modules N and volume flow V.

[00105] As one or more absorbers are passive, the flow rate through the active absorbers will be correspondingly greater. The pipe resistance is chosen so that it is energetically advantageous to achieve symmetrical circulation in all absorbers.

Claims (20)

1. Device for solar collector plate for flow correction of heat-carrying medium to be fed into a plurality of upstream channels in a solar collector plate, characterized in that the device consists of one or more guide elements (46,56) in a lower end channel (43,53) adjacent and opposite one or several supply openings (55) which cover part of the cross-section of the end channel (43,53). 2. Device for solar collector plate according to claim 1, characterized in that the device comprises a guide element (46,56) arranged adjacent to a side surface of the end channel (43,53) and adjacent to one or more upstream channels adjacent to the side surface of the collector plate (40,50). 3. Device for solar collector plate according to claim 1 or 2, characterized in that the device comprises a guide element (46,56) arranged adjacent to a side surface of the end channel (43,53) and adjacent to one or more upstream channels adjacent to the side surface of the collector plate (40,50) and on the opposite side of the end channel's (43,53) downstream channel . 4. Device for solar collector plate for flow correction of heat-carrying medium to be fed into one or more downstream channels in a solar collector plate, characterized in that the device consists of one or more guide elements (47) in an upper end channel (48), where each of the at least one guide element is located adjacent to a downstream channel. 5. Device for solar collector plate according to claim 4, characterized in that the device comprises a guide element (47) arranged adjacent to a downstream channel in the upper end channel (48). 6. Device for solar collector plate for flow correction of heat-carrying medium to circulate in a plurality of solar collector plates, characterized in that the device consists of at least one resistance element (49,r) arranged in one or more downstream channels in the solar collector plate. 7. Device for solar collector plate according to claim 6, characterized in that the at least one resistance element (49,r) is designed as a piece of pipe and where the piece of pipe has a smallest diameter that is smaller than the adjacent downstream channel. 8. Device for solar collector plate according to claim 6 or 7, characterized in that the at least one resistance element (49,r) is arranged in the smallest one downstream channel portion in the end channel (43,53). 9. Device for solar collector plate according to claim 6 or 7, characterized in that the device includes a resistance element (49,r). 10. Solar collector plate for circulation of a heat-carrying medium where the solar collector plate is designed with a first main part (30,40,50,100), a) the first main part (30,40,50,100) has the shape of a right-angled prism with rectangular end surfaces and two opposite rectangular lateral surfaces of length d defining a cavity with an opening at two opposite ends, with an internal height h, an internal width b and a depth d, where d>b>h, the first main part (30,40,50,100) further comprises several parallel upstream channels which run parallel to the side surfaces, adjacent to at least one of the side surfaces at least one return channel is arranged which is parallel to the upstream channels, b) further the solar collector plate comprises an integrated inlet and outlet manifold with inlet and outlet channels (51,101,52,102) which are parallel, the inlet channel (51,101) is provided with at least one opening (45,55) for the supply of heat-carrying medium to the first main part (30,40,50,100), the outlet channel (52,102) is provided with at least one opening for receiving the heat-carrying medium from the return channel, the integrated outlet and inlet manifold is engaged (47) with the lower open end of the first main part (30,40,50,100) so that the heat-carrying medium from the inlet channel (51,101) comes into communication with the parallel upstream channels, while the outlet channel (52,102) comes into communication with the at least one return channel, c) an upper end channel (48,108) is arranged at the opposite open end of the first main part (30,40 . 50,100) forms a closed volume for circulation of the heat-carrying medium. 11. Solar panel according to claim 10, characterized in that the inlet manifold is provided with a chamber (43,53) adjacent to said at least one opening (45,55), where the chamber (43,53) is located between the inlet manifold's inlet channel (51,101) and the first main part (30,40,50,100), adjacent to said at least one opening (45,55) and in the chamber (43,53) there is arranged at least one first restriction/guide (46,56) where the at least one first restriction/guide (46,56) is arranged opposite or close to opposite to the at least one first opening (45,55) so that the heat-carrying medium has a velocity vector approximately perpendicular to the parallel channels. 12. Solar panel according to claim 11, characterized in that an imaginary rectilinear axis extending parallel to the upstream channels and through the chamber (43,53) will pass through a center line in the longitudinal direction of the inlet channel (51,101) and outlet channel (52,102) and the parallel inlet (51,101) and outlet channels (52,102) are arranged adjacent to each other and so that one of the channels lies adjacent to the chamber (43,53). 13. Solar panel according to claim 10 or 11, characterized in that the outlet-inlet channel (51,101,52,102) is provided with at least one pipe-like body (49) in communication with the at least one return channel that conducts heat-carrying medium from the at least one return channel and through the inlet channel (51,101) with a mouth into the outlet channel (52,102 ). 14. Solar panel according to requirements 10-13, characterized in that the end channel (48,108) is provided with at least one second restriction (47) for the heat-carrying medium. 15. Solar panel according to claim 13, characterized in that the at least one second restriction (47) is arranged adjacent to the at least one return channel. 16. Solar collector plate according to any one of claims 10-15, characterized in that the solar collector plate is made in a special variant of PPS. 17. Solar collector module comprising at least one solar collector plate according to claims 10-16, where the solar collector module comprises: a) a first transparent cover plate (62,72), b) at least one solar collector plate (60) arranged below the first transparent cover plate (62,72), c) an insulation layer (61) arranged adjacent to and below the at least one the solar collector plate (60), and d) at least two fixing profiles (63,73,64,74) for fixing the first transparent cover plate (62,72), where one fixing profile (63) is adapted for fixing to a substrate. 18. Solar collector module According to claim 17, characterized in that the first attachment profile (63) has a length approximately the length d of the solar collector plate (60), the first attachment profile (63,73) is further provided with a projecting lip (65) for engagement with a complementary lip (66) arranged to it second fixing module (64,74), so that the first and second fixing module (63,73,64,74) are adapted to a "click connection". 19. Solar collector module According to claim 17 or 18, characterized in that the solar collector module further comprises a top profile in engagement with the solar collector plate (60) upper end and the transparent cover plate (62,72) upper end, and a bottom profile in engagement with the lower end of the solar collector plate (60) and the lower end of the transparent cover plate (62,72). 20. Solar collector system comprising, two or more solar collector modules according to claims 17-19 connected in parallel arranged side by side where fluid communication between the modules is provided by manifold connections (90), in each inlet channel (51,101) and outlet channel (52,102) there is a releasably arranged manifold connection (90), the two or more solar collector modules are further connected via the fixing devices (63,73,64,74).