NO20131136A1 - Systems for interconnecting solar panels - Google Patents

Abstract

This invention relates to a system for interconnecting one or more seals and seals containing this system, characterized in that the system comprises a plurality of T-shaped pipes and connecting pipes which are alternately connected in series via a pipe-in-pipe type interconnection to form a supply line and / or a pull-out line for a number of series-connected sealers in a row.

Description

SYSTEM FOR CONNECTING SOLAR COLLECTIONS AND SOLAR COLLECTIONS

This invention relates to a system for connecting one or more solar collectors and solar collectors containing this system.

Background

The sun irradiates the earth's surface with light which in sunny areas can amount to an energy flux of over 1 kW/m<2>. This constitutes a large energy flow that can be utilized to provide heat or converted into other useful forms of energy such as electrical energy, mechanical energy etc.

For households, solar heating is suitable to fully or partially cover the need for hot water and other heating of the household. This can be achieved by using solar collectors which are devices that utilize the energy in sunlight by absorbing the sunlight and transferring the energy in the sunlight as thermal energy to an energy carrier/thermal medium (a fluid). The thermal medium can flow to a device to use the thermal energy or to a storage tank etc. for later use in the household. In Norway, it is estimated that an amount of energy of up to 400 - 450 kWh/year per m2 solar collector can be extracted from the sunlight [1], i.e. that a few square meters of solar collectors on the household's roof can make a noticeable contribution to the household's heating needs and/or hot water needs.

Known technique

Traditionally, solar heating has been used to heat water in a tank with a dark surface water standing in the sun. Such a solar collector has low thermal efficiency due to relatively large heat losses to the solar collector's surroundings and thus produces both a low temperature of the water and low volumes of hot water. It is therefore common to include thermal insulation of solar collectors to increase the thermal efficiency in order to deliver a larger volume of hot water at a higher temperature.

A known and widely used solution for thermal insulation of the solar collector is to close the sunlight-absorbing part of the solar collector in an enclosure that is mainly transparent to the relatively short-wave sunlight but mainly opaque to the relatively long-wave heat radiation from the solar-absorbing part of the solar collector. In this way, both convective and radiation-based heat loss to the solar collector's surroundings is reduced, and enables the transfer of a larger proportion of the solar collector's thermal energy production to a thermal fluid/medium that acts as an energy carrier for transferring the thermal energy to an end-user location or thermal storage for later use. The need for thermal insulation of the sunlight-absorbing part in a solar collector increases the higher the temperature difference between the absorbing part and the solar collector's surroundings.

The thermal insulation of the absorption zone in the solar collector becomes optimal when vacuum is used, which reduces convective heat losses from the solar collector to close to zero. This can be achieved, for example, by using two concentric tubes where the innermost tube is the solar collector and coated with a sunlight-absorbing surface, and the outer tube is made of glass. By evacuating the outer tube (made of glass) to a low gas pressure (vacuum), the convective heat transfer between the inner tube (solar collector) and the insulating tube is reduced to a minimum. The thermal medium can flow on the inside of the inner tube and is heated by contact with the inner wall of the inner tube. This type of collector is often called an "Evacuated Tube Batch (ETB) collector". An example of ETB type solar collectors is indicated in US 4 987 883. A disadvantage of ETB type solar collectors is that they have a relatively low surface-to-volume ratio between the area of the sunlight absorbing layer and the volume of the thermal medium.

Another type of solar collector intended for buildings is so-called flat plate collectors. These solar collectors consist of at least two congruent plates placed in parallel and at a distance from each other so that a relatively narrow space is formed between the plates where a thermal fluid can flow. The plate that faces the sun is often made of a material that is mainly transparent to the relatively short-wave sunlight and mainly opaque to the relatively long-wave heat radiation that forms in the space between the plates, and the plate that faces away from the sun is often made of a material that absorbs light so that the plate is heated by incident sunlight (which has passed through the first transparent plate and the thermal fluid). Plate-shaped solar collectors often have one or more partitions oriented normal to the plates and placed between the plates to divide the space between the plates and form one or more flow channel(s) for the thermal fluid. The thermal fluid is fed to one end of the flow channel(s) via an inlet and withdrawn at the opposite end of the flow channel(s) via an outlet. An example of such a type of plate solar collector is indicated in US 4,297,990.

Plate-shaped solar collectors can be passive, i.e. the regulation of the flow of the thermal fluid occurs by temperature-driven natural convection, or active, i.e. the regulation of the flow of the thermal fluid occurs by forced convection.

Plate solar collectors have excellent surface-to-volume ratios between the area of the solar absorbing parts and the volume of the thermal medium and can deliver relatively large volumes of heated thermal fluids. A disadvantage of plate-shaped solar collectors is that they are not as well thermally insulated as ETB-type solar collectors and therefore do not work as well in cold climates where the temperature difference between the sunlight-absorbing part in the solar collector and its surroundings becomes relatively large. This is due, among other things, to the fact that since the thermal fluid is in contact with the first light-transparent plate, this will heat up somewhat and thus have a noticeable heat loss to the surrounding air. On the back side (the one facing away from the sun) this problem can easily be solved by applying an insulating layer of some material, but on the front side (the one facing the sun) it is required that the thermal insulation must be able to let the sunlight through without absorb significant proportions of the sunlight. A solution to this problem is known from WO 2011/089530 where a third congruent light transparent plate placed in parallel and at a distance above the second light transparent plate is used. In this way, the hot part of the solar collector, i.e. the first light-transparent plate and the light-absorbing plate including the thermal fluid, is isolated from the surroundings by forming an air-filled space with stagnant air which has an excellent thermal insulating effect between the hot part of the solar collector and the relatively cold surroundings. This is an insulation method that is analogous to how insulating glass for windows works.

Another disadvantage of plate-shaped solar collectors is that the solar collectors become sensitive to pressure changes in the space between the plates. The relatively large areas of the plates mean that small pressure differences between the inner space between the plates and their surroundings give relatively large pressure forces normally on the plates. This makes plate-shaped solar collectors particularly sensitive to temperature changes in the thermal fluid, which cause large volume changes in the fluid. In periods of low load, it is conceivable that the thermal fluid experiences being too strongly heated in periods of strong sun or, conversely, cooled down too much when it is cold outside. This can lead to problems with boiling of thermal fluids in liquid phase and vice versa; condensation of thermal fluids in gas phase or freezing of thermal fluids in liquid phase. In order to counteract such problems, it is desirable to be able to quickly drain the thermal fluid from the solar collector should such tendencies occur.

Costs are obviously a key issue for solar collectors intended for consumer sales. It is important to keep the costs of the product low in order to be competitive in the market.

The objectives of the invention

It is an objective of the present invention to provide a simple system for supplying and discharging thermal fluid to one or more solar collectors connected in series.

It is also an objective of the invention to provide a simple system for the supply and output of thermal fluid to one or more solar collectors connected in series and which in addition also functions as a system for connecting one or more solar collectors of the plate type in series.

It is also an objective of the invention to provide a solar collector which contains the system for supplying and discharging thermal fluid.

Description of the invention

The invention is based on the realization that solar collectors connected in series can be supplied with energy-carrying thermal fluid via at least one pipeline which can be quickly and easily assembled from a set of pipe parts which are connected together to form a pipe-in-pipe type connection in order to form at least one first pipeline for the supply of thermal fluid, and that exactly the same method can form at least a second pipeline for the removal of thermal fluid. This constitutes a simple and cheap construction in terms of production technology and assembly.

The invention thus applies to supply or extraction lines suitable for solar collectors connected in series in a row containing any number of n solar collectors. In practice, in the vast majority of cases this means that ne {1,2, 3, ...,100}. It is also conceivable to put together supply or extraction lines according to this invention intended for more than 100 solar collectors in a series-connected row.

In a first aspect, this invention relates to a system for forming a supply line 1 or an extraction line 2 for thermal fluid to a series-connected row of n number of solar collectors 3, where n e {1, 2, 3, ... , 100}, comprising: a number of n T-shaped pipes 10 adapted to be connected to the inlet 11 or the outlet 12 for thermal fluid of the solar collector 3,

a number of n-1 connecting pipes 7 adapted to connect T-shaped pipes in the supply line or the extraction line,

a plug tube 8 adapted to plug one end of a T-tube, and a connecting tube 5 adapted to be connected to a T-shaped tube,

where

the inner diameter of the connecting pipe(s) 7, the plug pipe 8 and the connecting pipe 5 is adapted in relation to the outer diameter of the T-shaped pipes 6 so that a tight connection can be formed by threading the end of the connecting pipes, the plug pipe and the connecting pipe respectively a bit over end to adjacent T-shaped pipe, or alternatively

the inner diameter of the T-shaped tubes 6 is adapted to the outer diameter of the connecting tube(s) 7, the plug tube 8 and the connecting tube 5 so that a tight connection can be formed by threading the end of each T-shaped tube a little above the end of adjacent connecting pipes, plug pipes or connecting pipes respectively.

This system can form a supply line or an extraction line for n series-connected solar collectors by assembling the part as follows: if n = 1 and a supply line 1 is to be formed, that it is formed by: the connection pipe 5 is connected to the upstream end of the T -shaped pipe 6 in the supply line, the T-stub 10 of the T-shaped pipe 6 to the inlet of the collector 3, and the downstream end of the T-shaped pipe 6 to the plug pipe 8, or if n = 1 and an extraction line 2 is to be formed , that it is formed by: the connection pipe 5 is connected to the downstream end of the T-shaped pipe 6 in the extraction line, the T-stub 10 of the T-shaped pipe 6 to the outlet of

the solar collector 3, and the upstream end of the T-shaped pipe to the plug pipe, or

if n > 1 and a supply line 1 is to be formed, that it is formed by:

- a first connecting link in the supply line is formed by the connection pipe 5 being connected to the upstream end of the first T-shaped pipe 6 in the supply line, the T-stub 10 of the first T-shaped pipe 6 being connected to the inlet of the first collector 3 in the series-connected row of solar collectors, and the downstream end of the first T-shaped pipe 6 to the upstream end of the first connecting pipe 7 in the supply line, - then follows a number of n = n-2 intermediate links in the supply line which are formed by the upstream end of the nth T- shaped pipe 6 is connected to the downstream end of the n'th-1 connecting pipe 7 in the supply line, the T-stub 10 of the nth T-shaped pipe Is connected to the inlet of the nth +1 collector in the series-connected array of collectors, and downstream end of the nth T-shaped pipe 6 to the nth connecting pipe in the supply line, - and then follows a last link formed by the upstream end of the T-shaped pipe 6 number n=n being connected to the downstream end of the connecting pipe number n=n-l in the supply line, T-stub 10 t il T-shaped pipe number n=n is connected to the inlet of collector number n=n in the series-connected row of

solar collectors, and upstream end of T-shaped pipe number n=n to plug pipe 8, or

if n > 1 and an extraction line 2 is to be formed, that it is formed by:

- a first connecting link in the extraction line is formed by the plug pipe 8 being connected to the upstream end of the first T-shaped pipe 6 in the extraction line, the T-stub 10 of the first T-shaped pipe being connected to the outlet of the first collector 3 in the series-connected row of solar collectors, and the downstream end of the first T-shaped pipe 6 to the upstream end of the first connecting pipe 7 in the extraction line, - then follows a number of n = n-2 intermediate links in the extraction line 2 which are formed by the upstream end of the nth T- shaped pipe 6 is connected to the downstream end of the n'th-1 connecting pipe 7 in the supply line, the T-stub 10 of the nth T-shaped pipe Is connected to the inlet of the nth +1 collector in the series-connected array of collectors, and downstream end of the nth T-shaped pipe 6 to the nth connecting pipe in the extraction line, - and then follows a final link formed by the upstream end of T-shaped pipe number n=n being connected to the downstream end of connecting pipe number n=n-l in the extraction line, the T-stub of T-shaped pipe number n =n is connected to the inlet of collector number n=n in the series-connected row of collectors, and the upstream end of T-shaped pipe number n=n is connected to connection pipe 5.

The first aspect of the invention is illustrated schematically in figures la and lb. Figure la shows a supply line 1 calculated to supply a row of three solar collectors 3, which are marked respectively with n=1, n=2 and n=3 in figures la and lb. The number of solar collectors in the figure is only intended as an illustration of the principle solution for connecting the supply or extraction line. Figure la does not show the extraction line 2, but from Figure lb it can be seen that it has exactly the same construction as the supply line and that the extraction line 2 is mirror-symmetrical with the supply line. This provides a simplified assembly of the system according to the invention in that both lines can be assembled by assembling the parts in the same order and following the same procedure with the exception of the first and last parts. The invention also has the advantage that since the system is composed of a number of identical parts with the exception of the first and last part, the system can be easily expanded to include several solar collectors in the row or, conversely, to remove one or more solar collectors if changes are required .

From Figure la or lb one can see that the supply line 1 consists in this example of a first (n=l) which comprises a connecting pipe 5, a T-shaped pipe 6, and a connecting pipe 7. The second link (n=2) comprises a T-shaped pipe 6 and a connecting pipe 7, while the third link (n=3) comprises a T-shaped pipe 6 and a plug pipe 8.1 this example, the outer diameter of the T-pipes 6 is somewhat smaller than the inner diameter of the connecting pipe 5, the connecting pipes 7 and the plug pipe 8, so that the connection between the T-pipes and one of the other pipes is achieved by inserting the ends of the T-pipes a little into the respective pipes they are to be connected to. Alternatively, one could just as easily use an opposite ratio on the diameter of the pipes so that the connection is achieved by having the T-pipes thread the ends of one of the other pipes a bit into them. Although the invention is illustrated and described with reference to the embodiment example where the ends of the T-tubes are threaded into the other tubes, it should be understood that the present invention includes embodiments that use T-tubes with a larger diameter than the connecting tubes, connecting tubes and plug tubes as described above .

Each T-shaped tube 6 has a tube stub 10 which is adapted to be connected to the inlet 11 or to the outlet of the solar collector 3. The present invention can use any known and conceivable way to connect the T-tube stub 10 with the inlet 11 or outlet of the solar collector, respectively 12 as long as the connection is sufficiently robust to avoid leaks of thermal fluid. For that reason, no details are shown regarding the sealing of this connection in figures la and lb. Examples of a simple and robust interconnection that is suitable for use with plate-shaped solar collectors, in particular plate-shaped solar collectors where the plates are made of glass or other fragile and breakable material, are illustrated in figures 2a and 2b.

In the same way, the present invention can use any known and conceivable seal 9 of the pipe-in-pipe type connection of pipes as used in the supply or extraction line according to this invention. However, the present invention can advantageously use a simple and robust seal which is achieved by one of the tubes which are threaded together at the ends being equipped with some deformable elevation on the outside of the end of the pipe which ensures that a sufficiently large elevation is created so that the elevation gets squeezed between the outer wall of the inner tube and the inner wall of the outer tube, and in that way forms a fluid-tight seal. This can, for example, be achieved by using one or more o-rings etc. In the design example shown in figures la and lb, the seal 9 is achieved by using two o-rings.

The invention can use any known and conceivable thermal fluid including fluids in gas phase or in liquid phase which are suitable as energy carriers for heating buildings, providing hot water for households and other low temperature applications. Examples of suitable energy carrying fluids include, but are not limited to; air, water, glycol, silicone oil, and any commercially available thermal fluid as long as the fluid does not undergo a phase transition in the solar collector's normal operating temperature range, which in practice will be from around 0 °C up to around 100 °C. It is, however, possible to imagine applications that would involve temperatures of the thermal fluid beyond this range so that the temperature indication should not be understood as limiting the invention.

The pipe parts that form the supply or extraction line according to the invention can have any dimension and design as long as they can form the specified pipe-in-pipe type of connection according to the first aspect of the invention and as long as the supply and extraction line is capable of supply and withdraw sufficient amounts of thermal fluid for the solar collector(s) to function as intended. The appropriate dimensioning of the pipe diameter and the design of the various pipe parts (connecting pipe, T-shaped pipe, connecting pipe and plug pipe) will depend on how large the volume flow of the thermal fluid should be and the physical dimensions and physical design of the solar collector ( e) which must be connected together. Appropriate size of the volume flow of the thermal fluid is a function of the size of the area of the solar collector's light-absorbing parts, the number of solar collectors to be connected together and the specific heat capacity of the thermal fluid.

In that the supply or extraction line according to the first aspect of the invention can be used for a highly varying number of solar collectors connected in series, and for all known types of solar collectors designed for low and/or medium temperature solar heating (for example home heating, hot water supply for households etc ), the dimensions of and the physical designs of the pipe parts in the supply or extraction line according to the invention can vary over a wide range. It is, however, within the skilled person's expected competence to make such dimensions in the practical implementation of this invention, and the present invention includes any known and conceivable design and dimensioning of the pipe parts, respectively connecting pipes, T-shaped pipes, connecting pipes and plug pipes, which can form a supply and/or extraction line according to the first aspect of the invention as defined in the attached claim 1.

The first aspect of the present invention can use any known and imaginable material that is suitable for forming fluid-carrying pipelines in the temperature ranges that solar collectors of this type are exposed to during normal operation, in practice from slightly above 0 °C up to 150 °C . Examples of suitable pipe materials include, but are not limited to; plastics including polyphenylene sulphide plastic (PPS plastic) and metals, including aluminium, copper, etc.

In the figures, the pipe parts (connecting pipe, T-shaped pipe, connecting pipe and plug pipe) are shown as linear pipe parts. This is a simple and advantageous design for forming supply and extraction lines for plate-shaped solar collectors connected in series. However, the use of linear pipe parts in embodiments of the invention shall in no way be interpreted as limiting this invention. For example, bent pipe parts can be used to form curved supply or extraction lines where appropriate, and other pipe designs can be used where appropriate.

The present invention is suitable for forming supply and extraction lines for plate-shaped solar collectors connected in series in that the T-shaped pipe 6 can have a relatively large internal diameter which provides a relatively large transport capacity of thermal fluid at low flow resistance. This provides advantageous good circulation of thermal fluid in the solar collector, which is particularly important for plate-shaped solar collectors. Plate-shaped solar collectors consist, as mentioned in the section "Known technology", of at least two congruent plates 13,14 placed in parallel and at a distance from each other so that a relatively narrow space 15 is formed between the plates where a thermal fluid can flow (not shown in the figure). The present invention can be used for plate-shaped all known and conceivable solar collectors, including but not limited to solar collectors where the rearmost plate in the plate-shaped solar collector is sunlight absorbent. Alternatively, both the rear and front plates in the solar collectors can be opaque to sunlight, in which case the front plate will act as a sunlight absorbing zone. Another option is to leave both the front and rear panels transparent and use a thermal fluid with sunlight absorbing properties. Regardless of the design, it is the back plate of plate-shaped solar collectors that is to be attached to the T-stub 10, and thus integrated with the first aspect of this invention. The term "rear plate" refers to the light-absorbing plate that faces away from the sun and forms the back of the solar collector. The term "front plate" as used includes the plate which is mainly transparent to sunlight and which forms the sun-facing side of the solar collector.

From figures 2a and 2b it can be seen that the fastening mechanism according to a second aspect of the invention consists of a hollow cylinder-shaped insert 16 which is threaded into the T-stub 10 of the T-shaped tube, and that the fastening of the rear plate 13 to the solar collector 3 achieved by a flange 17 on the insert 16 pressing the plate 13 down against the end wall of the T-stub 10. The pressure from the insert's flange 17 against the rear plate 13 is maintained by the insert 16 being equipped with threads 18 adapted to a thread groove 19 on the inner wall in the T-stub so that the insert can be screwed down into the T-stub and achieve that the flange 17 gets a firm grip on the plate 13. The connection is made leak-proof by using an o-ring or other form of elastic material 20 that is placed between the plate 13 and the end wall of the T-stub 10 and in that way gets squeezed between them. In the design example shown in Figure 2a, the T-stub 10 has a conical funnel-shaped extension at the end directed towards the back plate 13 and the elastic seal 20 is placed in the space delimited by the inner wall of the T-stub 10, the lower side of the back plate 13 and the outer wall of the insert 16.1 in this case, the elastic seal 20 should be dimensioned so that it is squeezed between these surfaces. In the design example shown in figure 2b, the T-stub 10 has a conical extension of the pipe wall up towards the rear plate so that a usable pressure surface is formed on the end of the T-stub against which the elastic seal can rest. Alternatively, it is conceivable to use an elastic intermediate layer, a flat (low build-up) elastic ring such as a jam glass knit or the like sandwiched between the flange 17 and the upper surface of the rear plate 13 (which faces the flange). Any known and imaginable elastic material can be used which can form a leak-proof seal at the pressure pressure (between flange 17 and rear plate 13), fluid pressure inside the pipe channel, and the temperatures that normally occur during operation of this type of solar collectors. Examples of suitable sealing materials include, but are not limited to, rubber rings, window putty, elastic sealants, caulking etc.

In Figures 3a and 3b, the insert 16 is illustrated schematically individually from the side and directly from above, respectively, while Figures 2a and 2b show examples of how the insert 16 is integrated with the supply or extraction line according to the second aspect of the invention. The invention can use any known and imaginable material in the insert as long as the material gives the threads 18 sufficient mechanical strength to achieve a steady and secure attachment to the T-stub's thread groove 19. Examples of suitable materials include, but are not limited to; metals, including aluminium, acid-resistant steel or plastics, including polypropylene plastic or polyamide plastic, etc.

Solar collectors of the plate type are, as mentioned, sensitive to pressure changes inside the fluid circuit due to the relatively large areas in contact with the thermal fluid. An overpressure (greater pressure inside the circuit than the surroundings) is generally more unfortunate than a negative pressure because the overpressure seeks to separate the plates 13, 14 in the solar collector from each other and can therefore easily lead to leaks of thermal fluid. It is therefore advantageous to use a pump placed on the extraction line downstream of the solar collector^) which sucks the thermal fluid out of the solar collector and thus creates a negative pressure in the part of the fluid circuit that is located upstream of the pump.

In a third aspect of the invention, the supply or extraction line according to the first or second aspect of the invention comprises an external closed circuit for thermal fluid. This closed circuit can advantageously have an insulated storage tank and the like for thermal fluid to provide storage capacity for solar heat and give the user the opportunity to use the solar heat regardless of when the sun is shining.

In cases where the thermal fluid is a liquid, such as water, as mentioned, problems can arise with overheating or subcooling that cause phase transitions, respectively boiling or freezing of the thermal fluid. This will result in a volume expansion which, in the worst case, can burst the solar collector(s). This problem is particularly relevant during periods when the solar collector system is inactive. Then cold degrees or strong sun can lead to freezing or boiling problems in the fluid circuit. To remedy this problem, it is an advantage to be able to evacuate the part of the fluid circuit where freezing or boiling problems can occur by the fluid being extracted and replaced by air. To achieve this, one can equip the supply line upstream of the solar collector(s) with a valve, for example a switching valve or similar, which is activated by a control system that engages the valve so that it closes off the fluid flow and opens for the introduction of air into the fluid circuit when the plant is to is evacuated, and the opposite which closes off the air supply and allows the liquid to flow freely through the valve during ordinary operation of the solar collector system. In this case, the pump on the extraction line can advantageously be an ejector pump or self-priming pump that can evacuate air out of the fluid circuit while ensuring that the fluid circulates inside the fluid circuit. The regulation system can be set up to regulate the operation of the pump and the valve based on information about the temperature of the thermal fluid in the solar collector(s). Alternatively, the evacuation of the solar collector(s) can be achieved by using a difference to the water level on the pipe that returns from the solar collector(s) so that when the circulation stops, the pressure column will be greater on the supply side of the solar collector(s) and thereby the water flows back via the supply.

An embodiment example of a closed fluid circuit for liquid with the possibility of evacuation is shown schematically in Figure 4. The figure shows five plate-shaped solar collectors 3 connected in series and where a supply line 1 according to the first or second aspect of the invention leads a relatively cold liquid into the solar collectors and an extraction line 2 according to the first or second aspect of the invention extracts relatively hot liquid from the solar collectors. Downstream of the solar collectors 3, an ejector pump 22 is placed which ensures that the liquid is sucked out of the solar collectors and further via pipeline 23 into a thermally insulated storage tank 24. The internal space of the storage tank is divided into a liquid-filled part 24a and an air-filled 24b expansion volume above the liquid phase to be able to receive and hold liquid that is evacuated from the solar collectors 3. The liquid level inside the tank is illustrated with a thin dotted horizontal line in the figure. As can be seen from Figure 4, pipeline 23 ends inside the expansion volume 24b in the storage tank 24 so that liquid that is pushed out of the end of pipeline 23 must fall a distance through the air in the expansion volume before it enters the liquid phase 24a in the storage tank. The storage tank has an opening 26 for the introduction or discharge of air in step with volume changes of the expansion zone 24b. The opening 26 can advantageously be equipped with a shut-off valve (not shown) which can be opened and closed by a control system that operates the plant. The pump 22 has an outlet for evacuating air (not shown) which is sucked out of the solar collector system. Alternatively, the pump 22 can pump both air and liquid into the storage tank 24, and allow the necessary ventilation of air sucked out of the solar collectors (when they are put into normal operation after being evacuated) to take place via opening 26. From the storage tank there is a pipeline 28 which transfers relatively cold liquid from the storage tank 24 and further into the supply line 1. With this, the fluid circuit becomes a closed circuit.

The pump 22 on the return line 23 creates a suction in the fluid circuit upstream of the pump. In cases where a liquid is used as a thermal fluid, this suction can create problems due to the pressure dependence of the liquid's boiling point, which can cause gas formation in one or more of the pipelines 28, the solar collector(s) 3 or the supply line 1 if the height difference between the storage tank 24 and the solar collector(s) 3 , the length marked with arrows A in Figure 4, causes a sufficiently strong boiling point depression in the liquid. For example, water will boil at around 50 °C if the pressure in the fluid circuit is reduced to around 0.1 atmosphere, which is achieved in the upper part of a 9 meter high water column which is sucked up, and at a 10 meter water column the pressure is in the upper part of the column down towards vacuum where the water boils at a temperature below 10 °C. In many applications it will therefore be necessary or at least advantageous to place a pump on the trip line 28 just downstream of the storage tank 24 which ensures that the pressure drop from the pump 22 in neither the solar collector(s), the supply line nor the return line falls to a level where the liquid's boiling point depression becomes a problem. For water, the pressure in the water phase should not fall below 0.3 atmospheres in the fluid circuit, or even more advantageously 0.5 atmospheres. Figure 4b schematically shows an embodiment example with a pump 29 placed on the trip line 28. The operation of pump 29 should be adapted so that it does not raise the liquid pressure in the trip line 28 to a level where the thermal liquid is actively pumped into the supply line by pump 29 on the trip line, but is sucked in by means of pump 22 on the return line in combination with the effect of gravity on the liquid in the return line's liquid column. Any known and conceivable solution for regulating the power and operation of pump 29 to achieve this intended effect can be used by the present invention.

As the return line in the fluid circuit (extraction line 2 and pipeline 23) ends at a distance above the liquid mirror in the storage tank 24, the liquid height (indicated by arrows marked B in Figure 4) in the return line is less than the liquid height of the trip line consisting of pipeline 28 and supply line 1 (indicated by arrows marked A in figure 4). Ergo, there is a greater gravitational fluid pressure in the flow line than in the return line, so that the thermal fluid can only circulate in the fluid circuit as long as pump 22 is in operation. As soon as pump 22 is stopped, the liquid pressure difference between the flow and return line will ensure that the liquid begins to flow in the opposite direction in the fluid circuit so that air is sucked in via the end of the return line (pipeline 23) which replaces the liquid in the fluid circuit until the liquid column in the flow line ( pipeline 28) is the same as in the storage tank. Then the entire solar collector system, including supply line 1 and extraction line 2, is emptied of liquid. This solution has the advantage that power outages or other unwanted outages of the circulation pump lead to automatic evacuation of the solar collectors and thus elimination of the risk of frost or overheating problems.

Down in the liquid phase, i.e. inside the volume 24a, a heat exchanger 25 with external flow circuit 25a and 25b is placed to supply one or more user locations (not shown) with solar heat via an energy-carrying thermal medium that is heated in the heat exchanger 25.

In a fourth aspect, the invention comprises a solar collector which results from combining the first, second and third aspects of the invention as defined in claim 16 or 17.

Figure list

Figure 1a is a schematic view seen from the side of an embodiment of a supply line according to the first aspect of the invention intended for the supply of thermal fluid to series-connected solar collectors. Figure 1b shows a schematic view seen from above of the same embodiment of a supply line as shown in Figure 1a and of an embodiment of an extraction line according to the first aspect of the invention intended for three series-connected solar collectors. Figure 2a is a schematic view seen from the side of a first embodiment of a fastening mechanism according to a second aspect of the invention. Figure 2b is a schematic view seen from the side of a second embodiment of a fastening mechanism according to a second aspect of the invention. Figures 3a and 3b are a schematic view of an insert according to the second aspect of the invention seen respectively from the side and from above. Figure 4a is a schematic diagram of an embodiment example of a closed fluid circuit for liquid with the possibility of evacuation integrated with a supply line and an extraction line according to the first, second or third aspect of the invention. Figure 4b is a schematic diagram of the same design example as in Figure 4a, but which also includes a pump on the trip line for pressure support. Figure 5a is a schematic view of an embodiment of the invention according to a third aspect of the invention intended for two series-connected solar collectors.

Figure 5b is a truncated section of the design example shown in Figure 5a.

Figure 5c shows a design example of a self-evacuating fluid circuit according to the invention.

Embodiment of the invention

The invention will be described here in greater detail with reference to an embodiment of the invention particularly suitable for supplying and extracting thermal fluid from series-connected solar collectors of the plate type that use transparent glass plates such as, for example, shown in WO 2011/089530.

The system according to this embodiment uses a supply and an extraction line according to the second aspect of the invention, and in addition exhibits a simple solution on how to connect the plates of the solar collectors with the supply and extraction line of an integrated solar collector unit. This is achieved by using a single aluminum profile which can be used to fasten the glass plates in the correct position and at the same time fasten the supply line and the extraction line to the solar collectors as shown in figures 5a and 5b, where figure 5a is a schematic drawing of the design example seen from the side, here in a version designed to connect two solar collectors and figure 5b is a truncated section of figure 5a to better illustrate the aluminum profile 140.

Figure 5a only shows the supply line, but as for the first and second aspect of the invention, the structure of the extraction line is completely similar. The supply and extraction line are mirror-symmetrical and are therefore made up of exactly the same parts. From figure 5 it can be seen that this design example uses the same attachment mechanism between the solar collectors' rear plate 113 and the T-stubs 110 to the supply and extraction lines as shown in figure 2a, i.e. by means of an insert 116 with flange 117 which presses the plate 113 down towards the T-stub 110.

The design example uses a number of aluminum profiles 140 which are all designed in the same way so that they have a leg part 141 for attachment to the substrate, and a wall-forming part 142 oriented normally on the leg part which extends up to just below the area where the solar collector's glass plates 113, 114 and 150 are to be attached . There, the wall of the aluminum profile splits into a straight back wall 143 and a bent profile part 144 which has attachment zones 145 and 146 which grip and hold/clamp respectively the ends of the glass plates 113 and 114, and 150 in the calculated position in the solar collector. In order to protect the glass plates 113,114, 150 against breakage, an elastic pressure-relieving and sealing material 147 can advantageously be used in the attachment zones 145 and 146. In the lower part of the wall part 142, the leg part, there is a circular opening 148 (not shown in figure 5b) where the supply line must be formed and a corresponding circular opening where the extraction line is to be formed.

As shown in Figure 5a, a simultaneous connection of pipe parts in the supply and extraction line and the plates in the solar collector is achieved by a first aluminum profile 140 (counting from the upstream end) having a T-pipe 106 with a flange 151 threaded through opening 148 so that the flange 156 is on the downstream side of the wall part 142. On the upstream side of the wall part 142, the connecting pipe 105 is attached to the T-pipe 106 by means of a clamping ring 149a which both attaches the connecting pipe 105 to the T-shaped pipe 106 and clamps the wall part 142 between the flange 151 and the clamping ring 149a. At the downstream end of the first solar collector, a connecting pipe 107 which is attached to the downstream end of the first T-pipe 106 is threaded through opening 148 in the second aluminum profile. The clamping ring 149a and the attachment zone of the T-tube 106 are threaded so that they can be screwed together. A third aluminum profile is positioned so that it is locked to the second T-shaped pipe 106 by being clamped between the T-pipe's flange 151 and a clamping ring 149b which also provides for locking together the downstream end of the connecting pipe 107 and the upstream end of the second T -shaped tube 106. Here, too, the clamping ring 149b is attached to the T-shaped tube 106 by means of threads so that they can be screwed together. The second and third aluminum profiles are mirror images of each other and stand butt-butt with the rear walls 143 facing each other. At the downstream end of the other solar collectors, a fourth aluminum profile is placed which attaches the downstream end of the glass plates to the other solar collectors. Alternatively, the clamping rings 149a and 149b can be replaced by nuts which are screwed into the threaded groove of the T-pipes 106 and let the nuts perform the locking of the wall parts 142 against the flange 151. In this case, the T-pipe 106 can achieve a fluid-tight connection with the connection pipes 105 and the connection pipes 107 respectively at the same pipe-in-pipe type connection as shown in Figure la.

With this configuration of the supply line and the corresponding mirrored configuration of the extraction line (not shown in the figures) a mutually locked structure is formed which ensures that the first and second aluminum profiles for each solar collector face each other and are locked at a distance from each other which ensures that the attachment zones 145 and 146 including the elastic pressure-relieving and sealing material 147 exerts a clamping pressure against the end surfaces of the glass plates 113, 114 and 150 so that they are both held in place and that a fluid-tight seal is formed along the end edges of the glass plates. A locking of each solar collector to each other in the row is also formed by the back wall 143 of the first aluminum profile of solar collector number n+1 in the row of n solar collectors, butting against and clamping onto the back wall 143 of the second aluminum profile of solar collector number n in the row.

In that the first and second aluminum profiles of each solar collector are mirror-symmetric (i.e. two copies of the same profile are oriented 180<0> in relation to each other), the embodiment according to the third aspect of the invention forms a simple system for connecting a number of n series-connected plate-type solar collectors which essentially comprise a number of 2n aluminum profiles 140, n glass plates 113 (coated with a sunlight-absorbing layer), n glass plates 114, n glass plates 150, 2n T-shaped tubes 106 with n clamping rings 149b, 2n-2 connecting tubes 107 , 2 plug pipes 108, and 2 connection pipes 105 including 2 clamping rings 149a.

The outer glass 150 can advantageously be glued to the aluminum profiles 140 so that they constitute a structural reinforcement of the construction and a visual improvement in that the glass lies flush with the outermost life of the construction.

This design example is integrated with a self-evacuating liquid circuit as shown in Figure 5c. During normal operation, pump 31 ensures that water is drawn out of the storage tank 24 and into the ejector pump 22, which is located downstream on the extraction line 2. From the ejector pump 22, a pipeline 23 runs that ends inside the expansion volume 24b to the storage tank some distance above the water level. The storage tank has an air duct 26 for evacuating or filling with air in step with volume changes in the expansion volume 24b. From storage tank 24 runs a pipeline 28 with circulation pump 29 which sends liquid into supply line 1. When pumps 29 and 31 are stopped, the pressure of the liquid column in the flow line (pipeline 23 and supply line 1) will ensure that the liquid starts to flow in the opposite direction as that the liquid is replaced by air (which enters via the end of pipeline 23).

Reference

1. Store Norske Leksikon 2005 - 2007, online edition,

http:// snl. no/ solar collectors/ energy technology

Claims (17)

1. System for forming a supply line 1 or an extraction line 2 for thermal fluid to a series-connected array of n number of solar collectors 3, where ne {1, 2, 3, ... , 100}, comprising: a number of n T- shaped tubes 6 with T-shaped stubs 10 adapted to connect to the inlet 11 or outlet 12 of thermal fluid of the solar collector 3, a number of n-1 connecting pipes 7 adapted to connect T-shaped pipes in the supply line or extraction line, a plug pipe 8 adapted to plug one end of a T-pipe, and a connection pipe 5 adapted to be connected to a T-shaped pipe, where the inner diameter of the connection pipe(s) 7, the plug pipe 8 and the connection pipe 5 is adapted in relation to the outer diameter of the T-shaped pipes 6 so that a tight connection can be formed by threading the end of the connection pipes, the plug pipe and the connection pipe, respectively, a little above the end of the adjacent T-shaped pipe, or alternatively the inner diameter of the T-shaped pipes 6 are adapted in relation to the outer diameter of the connecting pipe(s) 7, the plug pipe 8 and the connecting pipe 5 so that a tight connection can be formed by threading the end of each T-shaped pipe a little above the end of the respective adjacent connecting pipe , plug pipe or connection pipe. 2. System according to claim 1, characterized in that - the system further comprises a hollow cylindrical insert 16 adapted to thread into the T-stub 10 of the T-shaped pipe 6, and in that - the T-stub 10 to be attached to the solar collector 3 has a conical extension at the end facing the solar collector 3 and a threaded groove 19 on the inner wall at the opposite end of the T-stub 10, - the insert 16 has a flange 17 in it one end and threads 18 on the outer wall at the other end, where the threads 18 are adapted to thread grooves 19 so that they can be screwed together, and - the physical dimensions of insert 16 are adapted so that when it is screwed to the T-stub 10 that the flange 17 grips and clamps the rear plate 13 of the solar collector 3 down towards the end surface of the T-stub 10 which faces the solar collector. 3. System according to claim 2, characterized in that the conical expansion of the T-stub 10 consists of a funnel-shaped expansion of the inner diameter of the T-stub, - that the system further comprises a seal 20 located inside the funnel-shaped expansion of the T- the stub 10, and - that the seal is dimensioned so that it comes in a pinch between the outer wall of the insert 16, the inner wall of the funnel-shaped extension of the T-stub 10 and the surface of the rear plate 13 that faces the T-stub 10, because on the way to form a fluid-tight seal between the insert 16, the T-stub 10 and the solar collector back plate 13. 4. System according to claim 2, characterized in that the conical expansion of the T-stub 10 consists of a funnel-shaped expansion of the T-stub's 10 wall thickness, - that the system further comprises a seal 20 located between the T-stub's end surface 21 and the the surface of the rear plate 13 that faces the T-stub 10, and - that the seal is dimensioned so that it squeezes between these surfaces in order to form a fluid-tight seal between the end surface 21 of the T-stub and the solar collector's rear plate 13. 5. System according to claim 2 or 3, characterized in that the seal is made of an elastic fluid-resistant material selected from the group: rubber, window sealant, elastic sealants, or sealant. 6. System according to claim 5, characterized in that the seal is an O-ring. 7. System according to any preceding claim, characterized in that the T-shaped pipe 6, the connecting pipe 7, the connecting pipe 5 and/or the plug pipe 8 are made of one of the following materials; plastic, polyphenylene sulphide plastic, metal, aluminum or copper. 8. System according to any preceding claim, characterized in that: if n = 1 and a supply line 1 is to be formed, that it is formed by: the connecting pipe 5 is connected to the upstream end of the T-shaped pipe 6 in the supply line , the T-stub 10 of the T-shaped pipe 6 to the inlet of the solar collector 3, and the downstream end of the T-shaped pipe 6 to the plug pipe 8, or if n = 1 and an extraction line 2 is to be formed, that it is formed by that: the connection pipe 5 is connected to the downstream end of the T-shaped pipe 6 in the extraction line, the T-stub 10 of the T-shaped pipe 6 to the outlet of the solar collector 3, and the upstream end of the T-shaped pipe to the plug pipe, or if n > 1 and a supply line 1 must be formed, that it is formed by: - a first connecting link in the supply line is formed by the connection pipe 5 being connected to the upstream end of the first T-shaped pipe 6 in the supply line, the T-stub 10 to first T-shaped pipe 6 is connected to the inlet of the first s solar collector 3 in the series-connected row of solar collectors, and the downstream end of the first T-shaped pipe 6 to the upstream end of the first connecting pipe 7 in the supply line, - then follows a number of n = n-2 intermediate links in the supply line which are formed by the upstream end of the nth T-shaped pipe 6 is connected to the downstream end of the nth-1 connecting pipe 7 in the supply line, the T-stub 10 of the nth T-shaped pipe Is connected to the inlet of the nth +1 solar collector in the series-connected row of solar collectors, and downstream end of nth T-shaped pipe 6 to nth connecting pipe in the supply line, - and then follows a final link formed by the upstream end of T-shaped pipe 6 number n=n being connected to the downstream end of connecting pipe number n=n-l in the supply line, the T-stub 10 of T-shaped pipe number n=n is connected to the inlet of solar collector number n=n in the series-connected row of solar collectors, and the upstream end of T-shaped pipe number n=n to the plug pipe 8, or if n > 1 and an extraction line is to be formed je 2, that it is formed by: - a first connecting link in the extraction line is formed by the plug pipe 8 being connected to the upstream end of the first T-shaped pipe 6 in the extraction line, the T-stub 10 to the first T-shaped pipe is connected to the outlet of the first solar collector 3 in the series-connected row of solar collectors, and the downstream end of the first T-shaped pipe 6 to the upstream end of the first connecting pipe 7 in the extraction line, - then follows a number of n = n-2 intermediate links in the extraction line 2 which are formed in that the upstream end of the nth T-shaped pipe 6 is connected to the downstream end of the nth-1 connecting pipe 7 in the supply line, the T-stub 10 of the nth T-shaped pipe is connected to the inlet of the nth + 1 solar collector in the series-connected row of solar collectors, and the downstream end of the nth T-shaped pipe 6 to the nth connecting pipe in the extraction line, - and then follows a final link which is formed by the upstream end of the T-shaped pipe number n =n is connected to the downstream end of connecting pipe number n=n-l in the extraction line, T-st the end of T-shaped pipe number n=n is connected to the inlet of solar collector number n=n in the series-connected row of solar collectors, and the upstream end of T-shaped pipe number n=n is connected to connection pipe 5. 9. System according to claim 8, characterized in that the system further comprises: - a number of 2n aluminum profiles 140, - a number of 2 clamping rings 149a with a threaded groove, and - a number of 2n-2 clamping rings 149b with a threaded groove, where: the aluminum profiles 140 are designed so that they have: - a leg part 141 for fixing against the substrate, - a wall-forming part 142 oriented normally on the leg part and which extends up to just below the area where the solar collector's rear glass plate 113 is to be positioned and where it then divides up in - a straight rear wall 143 and - a bent profile part 144 which has - attachment zones 145 and 146 which grip and hold/clamp respectively the ends of the glass plates 113 and 114, and 150, and - two circular openings 148 in the wall-forming part 142 which allows respectively a supply line and an extraction line according to claim 5 or 6 to pass through the wall part 142, and where: - the 2n T-shaped tubes 106 have a thread groove a bit on the outer surface of the tube at the downstream end adapted to the thread groove of clamping ring 149a or clamping ring 149b, and - each of the 2n T-shaped tubes 106 has a flange 151 directly upstream for the thread track. 10. System according to claim 8, characterized in that the system further comprises: - a number of 2n aluminum profiles 140, and - a number of 2n nuts with a thread groove, where: the aluminum profiles 140 are designed so that they have: - a leg part 141 for fixing against the substrate, - a wall-forming part 142 oriented normally on the leg part and which extends up to just below the area where the solar collector's rear glass plate 113 is to be positioned and where it then divides up in - a straight rear wall 143 and - a bent profile part 144 which has - attachment zones 145 and 146 which grip and hold/clamp respectively the ends of the glass plates 113 and 114, and 150, and - two circular openings 148 in the wall-forming part 142 which allows respectively a supply line and an extraction line according to claim 5 or 6 to pass through the wall part 142, and where: - the 2n T-shaped tubes 106 have a thread groove a bit on the outer surface of the tube at the downstream end adapted to the thread groove of the nuts, and - each of the 2n T-shaped tubes 106 has a flange 151 directly upstream of the thread groove. 11. System according to claim 9 or 10, characterized in that each aluminum profile is equipped with an elastic pressure-relieving and sealing material 147 in the attachment zones 145 and 146. 12. System according to any of the preceding claims, characterized in that the system further comprises a closed fluid circuit for liquid comprising: - a pump 22 located downstream of the extraction line 2 - a pipeline 23 for transferring liquid from pump 22 to a - a storage tank 24 with an air-filled expansion volume 24a and venting channel 26 connected to the expansion volume 24a, - a pipeline 28 for transferring liquid from the storage tank 24 to the supply line 1, and - optionally an air outlet connected to the pump 22, and where pipeline 23 ends in the expansion volume 24b at a distance above the liquid mirror in the storage tank 24. 13. System according to claim 12, characterized in that the storage tank 24 contains a heat exchanger 25 flow-wise connected to a second circuit 25a, 25b for an energy-carrying fluid. 14. System according to claim 12 or 13, characterized by the pipeline 28 being equipped with a pump 29 which pumps liquid from the storage tank 24 to the supply line 1. 15. System according to claim 12, 13 or 14, characterized in that the liquid is water. 16. Solar collectors, consisting of a series-connected array of n number of solar collectors 3, where n e {1, 2, 3, ... , 100}, characterized in that it comprises: - a supply line 1 according to claim 1 assembled as defined in claim 8, - an extraction line 2 according to claim 1 assembled as defined in claim 8, and - a system for connecting the supply line 1 and of the extraction line 2 to the series-connected array of n number of solar collectors 3 as defined in any of claims 2 to 11 inclusive. 17. Solar collector according to claim 16, characterized in that it further comprises a closed fluid circuit for thermal fluid according to any one of claims 12 to 15.