WO2008009755A1

WO2008009755A1 - Integrated thermal solar collector and production method thereof

Info

Publication number: WO2008009755A1
Application number: PCT/ES2006/000424
Authority: WO
Inventors: Juan Carlos Merino Senovilla; Francisco Javier Maturana Montero; Carlos Alonso Sastre; Alberto Zamarrón Pinilla
Original assignee: Fundación Cidaut
Priority date: 2006-07-20
Filing date: 2006-07-20
Publication date: 2008-01-24

Abstract

The invention relates to an integrated thermal solar collector and to the production method thereof. During assembly, the collector is encapsulated using a plastic transformation process during which all of the components can be integrated and external functions can be added for mounting same in an environment such as a roof. The product and the production process have a very high capacity for the addition of functions and complex shapes while reducing mounting operations and times, with the encapsulation and the external functions being performed simultaneously. The manner in which the absorber of the sensor is produced is also an integrated process with ducts, collectors and an absorbing surface all forming one part. The absorbing element comprises two sheets (8, 9) of metal having high thermal conductivity, at least one of which is formed such that the ducts (12) required for the passage of the heat transfer fluid are formed when the two sheets are joined using a material having a lower melting point (11), said ducts being covered by a protective coat (10).

Description

INTEGRATED THERMAL SOLAR COLLECTOR AND PROCESS OF

MANUFACTURING

D E S C R I P C I Ó N

OBJECT OF THE INVENTION

The present invention relates to a flat-type solar collector intended to capture the energy radiated by the Sun for subsequent thermal exchange with a heat transfer fluid that runs through the interior of the collector. This fluid can be used, through the operation of an exchanger, to obtain domestic hot water, not discarding its use in other types of exchanges or energy transformations.

The object of the invention is to achieve a high performance, low cost and low weight solar collector with an integrated manufacturing process that reduces the number of operations and allows their automation.

The assembly or assembly of the product with all its components is done through a complete encapsulation process through plastic injection or compression processes, together with the transparent cover (preferably glass), sealing gasket, a thermal insulating blanket, an iron of insulated foam material and a rear outer skin; in order to shape the entire structure of the panel, the assembly and the functions at the same time. This makes it possible to achieve a product with lower weight, lower cost, more watertight in rainy conditions and allows the removal of the insulating material on the sides of the panel, using the plastic material of the housing itself as thermal insulator in said area. The absorber is formed by two sheets of a material of high thermal conductivity formed so that between them, once joined, the fluid passageways are formed. These plates are tightly joined in a welding process by means of a material with a lower melting point.

The absorber is protected with an inner lining of the ducts in order to avoid the deposition of materials contained in the heat transfer fluid and also add additional corrosion protection and thus extend the life of the collector.

BACKGROUND OF THE INVENTION

The collectors, collectors or solar thermal panels of flat type, according to the State of the Art, comprise the following elements:

- A transparent cover on the side exposed to solar irradiation.

- An absorber plate with a treatment on its exposed face that facilitates the absorption of solar irradiation and reduces the emission. This treatment can be from black paint to selective treatments using PVD. - Ducts connected to the front plate (usually by welding) made of a material with high thermal conductivity, so that the fluid that flows through said ducts is heated.

- Thermal insulation material in the lower and lateral areas of the collector to avoid energy losses. - A box or frame-shaped structure that houses the whole set, normally built by joining aluminum or steel profiles.

The construction of solar collectors is currently carried out through traditional, underdeveloped processes and using a high number of components, which entails a series of drawbacks, such as high production costs, low process automation, high weight of the collector and improved performance.

With regard to the design of the collector carrier box, the most widespread configuration is the joining of aluminum profiles or of folded steel sheets by traditional welding or riveting methods. This form of manufacturing is laborious and difficult to automate, which is a major inconvenience in terms of large-scale manufacturing. The flexibility in terms of design of these materials and processes is very limited, so the box can only become a simple frame around the components, without being able to integrate other functions.

The product-process design that we present based on plastics transformation allows to greatly increase the capacity of the process, its automation, the capacity of the design by adding functions, the simplification of assembly operations and the reduction of weight among others.

Document CH 631256 describes a solar collector in which the absorber is encapsulated by means of a thermal insulated foamed resin and this same material acts as a bottom insulator, in this way the mechanical requirements of the frame area cannot be separated with the insulation requirements Thermal base and design parameters are made with the same material. The differences that exist with the process we present is that the plastic material that encapsulates the product forms the frame, the structural functions and the roof integration functions and it is not its mission the thermal insulation of the entire panel base so it is not necessarily a foamed plastic and can be reinforced With fiber of different nature. In the patent that we present the insulator or layers of different insulators are obtained previously and then encapsulated with the rest of the components, being introduced as an insert in the injection or compression process. In document CH 631256, the material is injected in a single stage by placing a side barrier that makes it resist the penetration of plastic material into the absorber, encapsulating glass and the rest of the components. In the process described in the present invention, the sealing is done with the mold itself, since the injection is carried out in two steps as a two-component injection, in a first all components except the glass are encapsulated and in another injection in the same station is encapsulated glass with the same or different material, which gives a greater design capacity. As for the manufacture of the absorber, the CH 631256A5 patent is based on a corrugated or corrugated sheet without intermediate ducts and only two square profile collectors at the ends for the passage of the fluid.

In the utility model ES 258248, it is encapsulated with a cellular structure throughout the product and this same material forms, at the same time, the insulator, the structure and the encapsulation of the glass, so that the material that acts as a lower insulator, the one that makes a lateral structure and the one that encapsulates the crystal are the same. The material is foamed in order to achieve flexibility and insulation. The utility model has the same encapsulation concept as patent CH 631256, a completely encapsulated one. The collector that collects the present invention does not completely encapsulate in a single step, but first integrates components and encapsulates only in the frame area, and then encapsulates the edge of the glass, It can be with a different material. The side frame, made of non-cellular material, can form a composite with interior insulating and rear protection textiles. This improves the protection of the rear. The insulating foams can be of different material than the structural one of the frame. This gives greater freedom of design and functionality.

As for the design of the absorber elements, they can be divided into two lines:

The first consists of the union, mostly by welding or simple contact, of a flat metal plate with a series of welded copper tubes in the form of a grill. This is the most extended configuration. This system has a series of drawbacks, such as the poor contact between the absorber plate and ducts, which greatly hinders thermal exchange and, therefore, efficiency. This configuration also involves the realization of a large number of welds to form the grid of ducts (generally 8 to 12 parallel tubes attached to two collector tubes at the ends), which makes it a slow and expensive process, Apart from using a lot of material.

In the second line the absorber element can be achieved by joining two plates, at least one of them corrugated, so that the spaces that remain between the plates serve as a conduit and the upper plate itself is the one that is exposed to irradiation. The joining between the plates can be carried out by welding, as stated in, for example, US 4243020, JP 56110842 or JP 2298760, the latter being limited to the use of stainless steel. This welding, bead or spot, is, however, expensive in time and difficult to apply on thin plates. Other documents, such as GB 2129925 or JP 57002954 collect a bonding system using adhesive, a system that It presents little resistance to the tension derived from the projected pressure of the fluid, worsens the thermal conductivity of the assembly and makes the process more expensive.

The document ES 2082710 makes the connection between the plates by means of the interposition of a material of lower melting point, which can minimize some of the aforementioned drawbacks, but it presents others, such as the difficulty in positioning that joining material, the bottom plate, with a profile only reproducible by extrusion and using a considerable amount of material, and the section of the resulting duct, rectangular, which presents little resistance to the pressure projected by the fluid.

There is another way of obtaining an absorber element from two plates, in which the two plates are still welded, still flat, by cords and then forced to pass a high-pressure fluid through the space between the plates, so that these deform to form the ducts. Documents JP 57117746, JP 57193248 and JP 60223962 collect processes of this type. This system has a great complexity when using high pressure fluid and leaves the material in unfavorable conditions.

DESCRIPTION OF THE INVENTION

The solar collector that the present invention collects represents a great advance in terms of simplification and efficiency of the manufacturing process, reduction of the number of components, weight reduction, obtaining a high performance absorber element, and one of the most important aspects of integration of components and fixings either on the roof or in other environments. The manifold housing, in its preferred embodiment, encapsulates all the components of the absorber by means of plastic injection or compression processes. It encapsulates during the injection process, therefore, the transparent cover (only in its outline), the glass gasket, the absorber, the different insulators and the protective back layer. This process is carried out in one station but in two steps, producing on the one hand the encapsulation of the glass and on the other hand the rest of the functions. Although there is only one station, the encapsulation can be done in one material or in two different. Both injections are automatic and simultaneous, which allows a process of high production capacity and great freedom of design, being the two different materials. One of the advantages of this is that the more structural function of the frame and the more aesthetic and sealing function of the glass can be differentiated, which implies a clear difference and improvement over other patents in which a single material is injected.

In addition, in previous documents, the encapsulation material is always cellular (foamed), since it must simultaneously fulfill the structural and insulating functions.

The structure of the box can not only be reduced to a frame, but it can integrate a series of reinforcement ribs distributed over the entire surface of the panel due to the design capacity of the plastic injection processes. Likewise, the process allows to integrate in the molding stage accessories for the assembly and fixation of the roof collector and flaps for the tightness between panels, such as for example roof-shaped geometries between panels that replace lead plates or others that They are being mounted a posteriori today.

The insulating part of the collector can be formed by several layers of various materials. Some of them may be of woven material or non-woven fabric that partially penetrates the frame to convert it into a high-performance, low-weight composite.

The plastic structure in the frame area can also have a metal profile inserted, forming a plastic-metal hybrid structure that replaces the composite and serves to increase stiffness and dimensional stability. This hybrid structure would be generated in the injection process in a single step by over-injecting the plastic material onto the profiles, preferably aluminum.

The absorber is manufactured by a process that allows great freedom in the design of the ducts, ability to achieve high efficiencies, high production capacities and manufacturing economy. It consists of two sheets of metallic material with high thermal conductivity, preferably aluminum. At least one of the plates is properly shaped so that, when joining the two plates, the necessary conduits for the heat transfer fluid path are formed. These ducts can be constituted by a series of parallel channels or with curved geometries to improve efficiency and which lead to collector ducts at both ends. Other configurations, such as a single channel in the form of a coil, are also possible. The section of these channels can be circular or other that facilitates the transmission of heat to the fluid.

The plates are subsequently welded by means of a material with a lower melting point that is placed between both plates and by the action of heat they are welded. In this way a resistant and perfectly watertight element is obtained. During the welding process of the plates, tubes can be added in the absorber zones provided for fluid inlet and outlet, so that the connections are made to the Once in the same welding process of the plates, it is a fully integrated process to perform the absorber.

The face exposed to the irradiation of the upper plate receives a selective treatment that gives it high absorption and low emission by projecting a suitable material, thus avoiding complex deposition processes by selective PVD treatments. It is also possible to use more conventional processes such as spray paint for the application of absorbent treatment.

Formed ducts, an inner lining can be made in order to avoid the deposition of materials contained in the heat transfer fluid and also add additional protection against corrosion and thus extend the life of the collector. This inner coating adapts to the requirements of sealing, operating temperature, resistance to chemicals, depositions and corrosion.

DESCRIPTION OF THE DRAWINGS

To complement the description that is being made and in order to help a better understanding of the characteristics of the invention, according to a preferred example of practical implementation thereof, a set of drawings is attached as an integral part of said description. In an illustrative and non-limiting manner, the following has been represented:

Figure 1 represents a sectioned perspective view of a flat-type solar thermal collector made in accordance with the object of the present invention. Figure 2 shows a perspective detail of two adjoining panels with elements integrated in the edge to prevent the passage of water to the roof deck

Figure 3 shows a detailed sectional view of the collector where the structure of the panel is observed in greater detail, with the elements for roof mounting and the fabric embedded in the structural material.

Figure 4 shows a sectioned perspective view showing a possible embodiment of the box or frame by means of a plastic-metal hybrid structure.

Figure 5 shows a sectioned detail view of the collector where the absorber element is observed in greater detail.

Figure 6 represents, by way of example, variants of possible sections that the absorber element can present.

Figure 7 shows a detailed sectional view of the absorber with an intermediate plate that divides the ducts increasing the contact surface with the fluid.

Figure 8 shows a detailed sectional view of the manifold where an embodiment is observed in which the transparent cover is held by a frame in the form of a metal profile partially embedded in the manifold housing.

PREFERRED EMBODIMENT OF THE INVENTION In view of the figures outlined, it can be seen that the solar thermal collector that the invention, in its preferred embodiment, proposes, is constituted by a supporting structure or box (1) made of plastic material by injection process. The structure of the box can not only be reduced to a frame, but it can integrate a series of reinforcement ribs or supports on which the absorber (2) rests distributed over the entire surface of the panel. Likewise, it is possible to integrate accessories for the assembly and fixation of the roof collector in the molding stage (15, 17).

On the upper face, the collector is integrated with a glass or a sheet of transparent material (3). The encapsulation of the transparent cover (Fig. 8), in its preferred embodiment, is carried out in a second phase, it can be made of a plastic material other than the rest, or it could be performed indirectly, so that it is a frame metallic (20) partially embedded in the collector box. In the lower face of the collector, a closing plate or textile is integrated, preferably the latter (4) covering the entire lower area of the collector. Between the absorber element (2) and the closing plate (4) are placed one or several layers of different nature of heat insulating material (5). for example, mineral wool, textile or non-woven fiberglass and polyurethane fabric forming a multilayer insulation, each suitable for the required level of temperature and insulating capacity. In its preferred configuration, there will be a layer of insulating fabric (18) under the absorber and another layer of tissue (19) in the form of a back closure of the collector. Said layers of woven material are embedded at their ends by the injected plastic material to form the structural frame, thus forming a composite of plastic and fiberglass (Fig. 3).

The plastic structure in the frame can also be inserted a metal profile (14), forming a plastic-metal hybrid structure that replaces the composite and serves to increase stiffness and dimensional stability. This hybrid structure would be generated in the one-step injection process by over-injecting the plastic material onto the preferably aluminum insert profiles that are inserted over the frame.

The absorber consists of two plates (8 and 9) of metallic material with high thermal conductivity, preferably aluminum. At least one of the plates is properly shaped so that, when the two plates are joined, the conduits (12) necessary for the heat transfer fluid path are formed. These ducts can be constituted by a series of parallel channels or with curved geometries to improve efficiency and which lead to collector ducts at both ends. Other configurations, such as a single channel in the form of a coil, are also possible. The section of these channels can be circular or other that facilitates the transmission of heat to the fluid.

The plates are subsequently welded by means of a material with a lower melting point that is placed between both plates and by the action of heat they are welded. In this way a resistant and perfectly tight element is obtained. During the plate welding process, tubes can be added in the absorber zones provided for fluid inlet and outlet, so that the connections are made at the same time in the same plate welding process, making it a fully integrated process of performing the absorber.

The outer face of the upper plate can receive a selective treatment layer (13) that gives it high absorption and low emission by projecting a suitable material. The section of the ducts formed by the absorber plates can have different variants, as shown, by way of example, in Figure 6. The plates can be formed both or only one of them, lower or upper.

Formed ducts, an inner lining can be made in order to avoid the deposition of materials contained in the heat transfer fluid and also add additional protection against corrosion and thus extend the life of the collector.

A variant of the arrangement of the described conduits, parallel that converge in collectors, can be a single coil-shaped conduit or any other form capable of being made by forming sheets.

The selective treatment (13), in addition to the preferred embodiment by spraying or painting, can be applied by other means, such as anodizing, nitriding, PVD deposition, etc., before or after the plate is formed.

Claims

R E I V I N D I C A C I O N E S

^I-.- Integrated Solar thermal collector, flat type intended for capturing solar radiation for subsequent heat exchange with a heat transfer fluid that runs through the inside thereof, characterized in that all or some of the different component elements thereof, The transparent sheet, the gasket for it, the absorber with the fluid conduits, the insulators, the structural profile of the frame and the back cover are integrated and encapsulated by a layer of plastic material that constitutes the supporting structure as a priority.

2 .- integrated according to claim 1, Solar thermal collector characterized in that tabs, visors and other elements for direct integration into the roof are integrated preventing the flow of rainwater cover elements that can be injected in the same material plastic housing or be inserted during injection or compression molding.

3 .- Integrated Solar thermal collector according to claim 1, characterized in that the structure housing the components of the manifold includes a series of reinforcing ribs distributed over the entire panel surface.

4 .- integrated according to claim 1, characterized by the existence of layers of woven or non-woven fabric-insulating and structural purposes, partially embedded by the structural plastic material to form a composite structure thermal solar collector.

5 .- Integrated Solar thermal collector according to the preceding claims, wherein the plastic material forming the box it integrates a profile of metallic material that is inserted as an insert in one or several pieces in the area of the frame before injection or compression, forming a metal-plastic hybrid structure.

6 .- integrated, according to previous claims, thermal solar collector characterized in that the casing or encapsulating structure and the components supported collector is made of a foamed plastic material.

7 .- integrated, according to previous claims, thermal solar collector characterized in that the casing or encapsulating structure and the components supported collector is made of a plastic material reinforced with fiber cut or knit.

8 .- integrated, according to previous claims, thermal solar collector characterized in that the absorber element is formed by joining two plates, formed at least one, and joined by the interposition of a material of lower melting point which subsequently It is fused between the two, so that at least one conduit is created for the path of the heat transfer fluid between both plates.

9 .- Integrated Solar thermal collector according to the preceding claims, characterized in that the fusible material that facilitates bonding between the plates of the absorber is applied by a spray process.

10 .- integrated, according to previous claims, thermal solar collector characterized in that the fusible material that facilitates bonding between the plates of the absorber is an intermediate plate from said material.

1 I ^a .- Integrated solar thermal collector, according to the claims above, characterized in that the fusible material that facilitates the union between the plates is a powder material alone or with a combination of other materials.

12 .- integrated, according to previous claims, thermal solar collector characterized in that the absorber element is formed by joining more than two plates, having the intermediate plates function to increase the contact surface with the heat transfer fluid, being positionable so complete on the entire surface or only on the inside of the ducts.

13 .- manufacturing process integrated solar thermal collector of the preceding claims, characterized in that it consists in a process of integration and packaging of components of the manifold with a plastic material by injection or compression processes plastic, and so that The plastic material itself also configures the supporting structure of the collector.

14 .- The process of manufacturing solar thermal collector integrated claims 1 to 12, wherein the joint between the plates forming the absorber element is made by adhesion.