WO2010071394A1 - Plastic solar collector for fluids - Google Patents

Abstract

The invention comprises a flat solar collector, that uses a black cellular plastic panel as a heat exchanger, a transparent cellular plastic panel as a protective thermal cover and a panel of thermal material on its back, all contained by an aluminium channel frame. This system provides equipment that is easy to manufacture, on account of the simplicity of the materials of which it is made. Their lightness simplifies transportation and installation in difficult areas on roofs and flat roofs, and being made of plastic, it is very resistant to impact from hailstones, stones or branches, extending the service life of the equipment, in addition to the fact that this equipment is highly efficient, achieving high fluid temperatures in short times, and taking into account the relatively low cost of the materials and the manufacturing processes, this equipment can be marketed at prices much lower than current prices, making it financially accessible to larger sectors of the population and considerably reducing the consumption of other energy sources used to heat water, which are increasingly expensive, in addition to the fact that said energy sources contribute to global warming of the planet, emitting gases harmful to the atmosphere during combustion.

Description

 SOLAR PLASTIC FLUID COLLECTOR

DESCRIPTION:

OBJECT OF THE INVENTION

The objective of the invention is to use solar energy, to heat water or fluids, in a simpler, light, economic and efficient way, facilitating its manufacture and installation, making this technology more accessible to the less favored population sectors.

According to an investigation, it has been found that some inventors are using similar systems, such as the one registered in Moldova Russia by Mr. Kovalenko Nikolae who has the N ⁰ record. MD2802 dated 2003 11 14 where it uses a plastic panel, which forms internal channels, where it circulates the water, this plastic panel has a transparent face and the other one of solar energy absorption that allows its heating by what the water circulates from one end to the other, increasing its temperature.

Another similar system is that used by Mr. Helmstaedter Werner from Germany, with registration N ⁰ . DE 20308205 U dated 2003 05 22. This is a system of structured plastic or metal sheet for roofs to which some pipes are fixed and has a thermal coating on the bottom, so that said tubes are between the sheet and the thermal coating, so that through the tubes the fluid is circulated, which is heated as it passes through them, taking the heat of the sheet exposed to the sun.

Another similar system is that used by Mr. Jaques Bernier of France, with registration N ⁰ . FR 2699991 dated 1992 12 28. This is a panel with two layers of corrugated sheet, welded or joined forming oval-shaped tubes, these sheets can be made of metal or plastic material, below the tubes carries a material . _^

thermal and above it has a transparent panel that covers the collector; the water is circulated inside the tubes, which with the panel exposed to the sun heats up and transfers heat to the water.

Another one we find is the one used by Mr. Francois Savigny from France, with registration N ⁰ . FR 2689157 dated 1992 03 31. This is a plastic panel with inner cells through which the fluid that feeds through the ends circulates, in these panels, the upper face is left transparent and the lower one is painted to capture the radiation solar this plastic panel, is covered with a glass and placed on the roofs of houses to heat the water.

TECHNICAL PROBLEM TO BE SOLVED.

The most important technical problems to solve when designing a solar collector system are: Define which exchanger system is going to be used, or in what way we will transfer the heat from the sun to the fluid, in the most efficient way possible, taking into account all the factors involved such as the daily solar path, the necessary flow that must circulate through the exchanger, the maximum temperatures to be achieved, the space available to place the systems. The materials to use, taking into account if cost, useful life, availability and efficiency. Solve in the most efficient way possible, heat losses, which can be generated by wind or rain or simply by the temperature differential between the system used and the ambient temperature. Give efficient solution to the joints between materials to avoid leaks of the fluid and to work with higher pressures, without causing leaks.

In the systems that were investigated we find some technical details that do not explain how they were resolved, as in the invention of Mr. Helmstaedter Werner of Germany, the manufacturing process for fixing the tubes in the back of the sheets can be complex and could have failures over time, because these unions between two different materials, with Ia _,

contraction and dilation of the bodies due to temperature changes can cause them to take off and being in the

interior between the sheet and the foaming, its detection and repair would be very complicated.

In the system of Mr. Jaques Bernier of France, it would be the union between the corrugated sheets, because the pressures generated inside can cause them to take off causing the fluid to accumulate forming large bags inside, in the same way, that at the junction point where it was detached from the other sheet, it can generate a hole through which the fluid would leak, thus preventing its proper functioning.

In systems where the panel is covered with glass, there is the problem that in principle, glass is a material with a good temperature conduction, and does not efficiently serve as a thermal barrier, which in this case is one of its functions and on the other hand its fragility, so that care must be taken in its manufacture and transport as well as in the place of installation, preventing them from being hit by objects that can break them, they are also used for manufacturing of solar collectors, metallic materials such as the coil itself, of copper or the fins attached to the tubes, which are made of materials that easily conduct heat through which they also easily lose it.

The convection of heat is an important variable to consider for the use of solar radiation, since wind gusts, at a lower temperature, that make contact with the exposed surfaces of the collector, absorb some heat that must be transmitted or has been transmitted to the fluid, causing the equipment to lose efficiency.

BRIEF DESCRIPTION OF THE INVENTION.

The present project was developed, because it was detected that existing systems could be perfected using common materials, easily accessible, making them lighter, facilitating transport, installation, improving efficiency and impact resistance, prolonging the useful life of the equipment.

In our invention, a polycarbonate cellular plastic panel cover is being used, which fulfills the function of thermal insulation, since in addition to said material being a bad conductor of heat, it is made of two laminates joined by small perpendicular ribs , forming cells, which helps to retain the temperature inside the panel since the outer laminate is separated from the interior by the cells containing air, fulfilling the function of thermal barrier. This cover panel, as well as the entire collector, must be sealed tightly, to avoid moisture ingress, which with condensation generates heat and, therefore, fogging of the transparent cover, this would prevent the efficient passage of solar radiation and affect The proper functioning of the equipment.

A cellular plastic panel is also being used as a heat exchanger, through which the fluid circulates, it carries the face towards the sun of black color and that is placed inside, of an aluminum frame, with thermal protection inside and inside a thermal panel in the rear part to avoid losses, the clear foam panel functions as thermal crowbar outward, separating the inside of the panel, between the two ^laminates' plastic, wherein the heating chamber is formed of wind currents or rain from outside. Using materials with low thermal conductivity and high heat absorption or retention, it is possible to increase the efficiency in these equipments. The components used in the present invention are made of poly-carbonate or pet cellular laminated plastic due to the mechanical properties of these materials, such as for example the resistance to degradation and yellowing, important for the useful life of the collector and therefore They are low maintenance, also have high impact resistance. In practice, currently, many manufacturers use the glass, because of its transparency and resistance to yellowing, but due to their fragility, they use them tempered to increase their resistance, but this makes them expensive anyway, they are at latent risk of breaking since they are usually installed on roofs and roofs . .

inclined where they are at risk of being hit by objects such as stones or tree branches.

BRIEF DESCRIPTION OF THE FIGURES

Figure N ⁰ . 1.- exploded view of the collector where it is seen that it consists of:

(1) Cover panel.

(2) Exchanger panel.

(4) Thermal plate.

(5) Marco.

(6) Feed tube

(7) Outlet tube

Figure No. 2 - sectional view of one end of the solar collector.

(1) Cover panel.

(2) Exchanger panel.

(3) Heat chamber

(4) Thermal panel.

(5) Aluminum frame.

(6) Plastic or grooved metal feeding tube.

(8) Seal.

Figure N ⁰ . 3.- Detail of the coupling between the exchange panel and the fluid inlet and outlet tubes.

(2) Exchanger panel.

(6) Plastic or metal inlet tube with groove.

(8) Seal.

Figure N ⁰ . 4.- Detail of laminated roof panel (1) (1a) Exterior laminate (1b) Interior laminate _,

(1c) Perpendicular ribs (1d) Channels or dry cells

Figure No. 5.- Detail of wet exchanger laminated panel (2) (2a) Upper laminate with black surface (2b) Lower laminate (2c) Perpendicular ribs (2d) Channels or cells through which the fluid to be heated circulates

DETAILED DESCRIPTION OF THE INVENTION.

The present invention consists of a system for heating fluids using solar energy, based on a simple, efficient design, easy to manufacture as well as transport and install, made with common and economical materials, facilitating access to this technology, to sectors of The less favored population, thinking of satisfying the savings needs in the consumption of fuels used to heat the water that are increasing its price day by day.

This invention was designed primarily for domestic use, although it can also be used in industrial systems or for heating pools in sports clubs or private use, taking advantage of solar energy, which until now, is free. This technology has had a relatively high cost, using the best known systems today such as vacuum glass tubes or copper tube coils, which are fragile and high-cost systems, far from the purchasing power of a large sector of the population of developing countries.

DESCRIPTION OF THE COLLECTOR BY PARTS:

In Figure 1, the exploded view of the collector formed by a first dry cover panel (1), separated from a second wet panel (2) that works is shown as an exchanger, with fluid inlet and outlet tubes. (6) and (7). Between the two plastic panels, although it is not visible in this figure, a heat chamber (3) is formed. On the rear part there is a panel of thermal material (4) to avoid loss of temperature, all these panels, framed by an aluminum channel (5) with thermal protection, assembling the solar collector in a single unit.

(1) TRANSPARENT COVER PLASTIC PANEL

The dry cover panel (1) is made of transparent cellular plastic material, formed by a first dry sheet (1a) facing outwards, separated from a second dry sheet (1b) facing inwards, joined by dry ribs (1c) perpendicular, of ta! so that dry channels or dry cells (1d) of air are generated between said sheets, functioning as thermal insulator. This dry panel is placed with the cells in a transverse position to structure in this direction and has the function of letting solar radiation pass to the black panel, where heat is generated, and preventing it from being lost by wind or rain. surrounding the collector, so that a large temperature differential between the outside and the inside temperature of the collector is achieved, the efficiency can be increased, if in the dry cells (1d) of this first panel (1) a vacuum is caused or if an inert gas such as Helium is injected, in this way the thermal barrier would be further improved.

(2) WET PLASTIC PANEL AS EXCHANGED

This wet panel (2) is also made of cellular plastic material, and can be made of black or painted material, this is formed by a first wet sheet (2a) separated from a second wet sheet (2b) joined by wet ribs (2c ), in such a way that channels or wet cells (2d) are generated. This wet panel is placed with the cells in longitudinal position and a fluid is circulated between the sheets (2a and 2b) and through the cells (2d), functioning as a heat exchanger, since the fluid circulating through its inside has a lower temperature, than that of the black panel exposed to the sun, so that the fluid circulating through them absorbs the temperature of the panel achieving a differential between the temperature of the fluid inlet and outlet.

(2) PLASTJCO HUMID PANEL FEEDING THE FLUID AND SEALED:

The wet panel (2) is fed from the fluid by two tubes, one inlet (6) and one outlet (7) at the ends, placed transversely to the flow of the liquid through the wet cells, these tubes, can be of plastic or metallic material, each of said tubes is made a groove (6a, 7a) longitudinally in its central part with a length and thickness that coincides with that of the plastic panel so that it is inserted into the tube. In order to avoid the flow of fluid, at the junction between the tubes (6, 7) and the ends of the wet panel (2) a seal (8) is formed, this can be made of different materials such as silicones, resins or glues, but considering that They must tolerate the working temperatures that can exceed 90 ⁰ C. They must have resistance to degradation and the fluid with which it will be in contact and thus avoid leaks of the fluid in this junction. The useful life of the equipment will depend largely on the quality of this seal. The seal (8) is preferably made inside the inlet tubes (6) and the outlet tube (7), since the pressure generated by the fluid inside, keeps the seal (8) pressed against the wall internal of the tubes, against the joint groove and the material of the plastic panel, so that a better sealing is ensured; in the event that this seal (8) is placed on the outer side of the tube, the pressure generated by the fluid inside, would force the sealant material to detach from the surface of the tube or panel (2) more easily creating leaks of fluid Although only the coupling between the wet panel (2) and the inlet tube (6) with the groove (6a) is illustrated in Figure 3, in assembly between said wet panel (2) and the outlet tube (7) It is exactly the same, but at the opposite end of the panel. The wet panel (2) has a "V" shaped cut at its ends, these form bevels in the wet channels (2d) that allow the circulation of the fluid even when the panel is inserted until it stops inside the tubes at its ends

(3) HEAT CHAMBER:

Inside the collector, a heat chamber (3) is formed between the dry panel (1) and the second wet black panel (2). In this chamber, the heat is generated, when the solar radiation affects, on the black surface of the wet panel, being trapped inside by the thermal barrier that forms the dry panel and the frame (5) having exit only by means of the fluid circulating inside the wet panel (2).

This effect is the same as that generated between the outer space and the interior of our terrestrial atmosphere, since solar radiation travels through space without generating heat, this solar radiation passes through our atmosphere and when affecting opaque bodies or materials In the earth, heat is generated and it is trapped inside the atmosphere, since it is known that in space there is a vacuum that acts as a thermal barrier that prevents heat from escaping.

In the case of this solar collector, the solar radiation crosses the transparent transparent plastic panel (1) and affects the surface of the wet plastic panel (2) of black color where the heat that is trapped inside the chamber is generated of heat (3) since the plastic panel of the transparent cover, acts as a thermal barrier, preventing heat from escaping, giving it the main output of said heat, by means of the fluid that circulates inside the wet panel (2 ) by heating said fluid to temperatures that can exceed 90 ° c.

WHY THE BLACK COLOR?

This wet panel (2) must be black, because it is the color that best transforms the energy of sunlight or solar radiation, into heat energy as it does not reflect it, it absorbs and retains it, generating a higher temperature than other colors, as can be seen with its extreme counterpart, the white color, these absorb light and reflect heat, therefore, they practically do not generate heat on its surface .

This principle can be verified according to the German scientific Max Planck law that in the year 1900 discovered that the wavelength generated by a color in which the maximum heat emission occurs, Ia generate black bodies, in comparison with bodies of any other color, due to the little refraction of the light so that the black bodies absorb the radiation and generate the higher temperature by transforming more effectively the solar radiation into temperature.

(4) THERMAL PANEL:

In the rear part of the collector carries a thermal plate (4). This thermal plate, (4) can vary in its thickness because there are different materials that are more or less efficient, as well as different costs, but they all perform the function of thermal barrier, and it is placed to reduce temperature losses by The rear part of the panel, by the part that faces the outside of this thermal plate, must be protected from the weather, being able to be with stainless steel sheet, galvanized or aluminum sheet, of some plastic panel or covering the surface exposed to Ia weathering with tarpaulin, simply for protection from degradation and damage caused by tears or bumps during storage, transport or installation.

(5) FRAMEWORK:

To assemble the collector, it is made with a four-sided aluminum frame in the form of a channel, to which a thermal protection layer is placed inside, where the transparent panel (1) is fixed and sealed in the upper part of the frame, in the central part of this, carries the wet black panel (2) and to the stringers holes are drilled from the aluminum frame so that the feed and outlet pipes (6 and 7) pass through, taking into account that the plastic material of the wet panel (2) has an important expansion and contraction with temperature changes On the one hand, the hole should be left elongated about 7 mm. which is the difference in dimensions between the minimum and maximum working temperatures, between the dry panel (1) and the wet panel (2) the heat chamber (3) is formed in the rear part the panel of thermal material is fixed (4) that, as we mentioned earlier, it must be protected from the weather and from bumps or tears during transport and installation with some laminate or film. In this way the collector is armed and closed forming a unit.

COLLECTOR PLACEMENT:

For optimal operation, these collectors should be placed inclined with the front towards the path or daily path of the sun, taking into account that there are no objects such as constructions or trees that obstruct and generate shade on the collector (s) during the hours of solar incidence The fluid must be fed through the tube (6) and the fluid outlet through the tube (7) on the opposite side of the feed, and with a slightly higher inclination towards the end of the outlet, this guarantees that the fluid, completely fill the wet channels (2d) and the inlet and outlet tubes (6 and 7) in this way, the fluid will be in contact on the entire surface of the cells (2d) and can efficiently absorb the heat generated in The wet panel plate (2a). They can be installed with a thermo-tank in the upper part of the collector and by means of the principle of (THERMOSIFON) circulating the heated fluid inside the wet panel (2) towards the thermo-tank and taking the fluid at a lower temperature of the same, heating the fluid inside the thermo-tank without using any forced system as it would be with an electric pump, in this way the fluid heated during the hours of solar incidence, can be used during the hours where there is none, recovering temperature again when it exists again. The thermo-tank can also be placed in any location, forcing the circulation of the fluid by means of a controlled electric pump with a thermostat device that orders the ignition to a determined temperature, as well as interrupt its operation when the temperature decreases, this system is also used for operation in swimming pools.

They can be placed interconnected in line or in parallel, to achieve a greater flow of circulation and to heat large volumes of water, for swimming pools or large thermo tanks for industrial use.

BEST WAY OF CARRYING OUT THE INVENTION.

Even when there are similar inventions for the heating of fluids capturing solar radiation, the present invention has elements that allow more effective use of solar incidence, this is achieved by the first panel (1) which is made of transparent cellular plastic material such as polycarbonate or pet, where the first dry sheet (1a) allows the passage of light through the first cells (1d), the second dry sheet (1b) and even the first dry ribs (1c), towards the exchanger panel (2), in which, at least its first wet sheet (2a) must be painted in matt black or preferably constructed entirely of material in black or matt black. Due to the effects already mentioned previously, light colored bodies absorb light, and repel heat, which in dark colored bodies work in reverse, that is, they absorb heat and their surface is heated, therefore that the radiation that affects the second wet panel (2) heats the first wet sheet (2a), so that the heat is retained by the material and through the wet ribs (2c) that function as heat catching fins and of contact surface to transmit this, to the second wet sheet (2b) by heating the entire body of the second wet panel (2), so that the fluid circulating through the wet channels or wet cells (2d) is conducted by surfaces hot ensuring that it absorbs the temperature of the plastic panel, thus achieving its heating. The radiation that will be reflected from the second wet panel (2) again affects the inner face of the first panel (1), but now it does so in the second dry sheet (1b) and by the known phenomena of light and heat absorption , heat waves _,

they are reflected by said second dry sheet (1b) again towards the first wet sheet (2a) of the second wet panel (2), in this way the temperature chamber (3) between the second dry sheet (1b) of the first panel is achieved (1) and the first wet sheet (2a) of the second panel (2) the temperature in this chamber rises considerably, and the heat generated is retained in the chamber (3) and forced to go through the body of the second wet panel (2) in its first wet sheet (2a) and up to the second wet sheet (2b) through the ribs (2c) forcing the transfer of heat mainly to the fluid flowing through the wet cells of the panel (2). The heat losses due to convection due to the contact of the air currents, the thermal radiation of the same equipment and different climatic conditions is reduced, since there is at least one air barrier that acts as a thermal barrier, which increases its efficiency could be of vacuum or of some gas in the first dry channels or dry cells (1d) formed between the second dry sheet (1b) and the first dry sheet (1a) of the first panel (1). The dried ribs (1c) of the first panel (1) are inefficient heat conductors, since being of clear plastic material they do not absorb heat considerably, so the heat is retained in the sealed chamber (3) this increases the temperature of the second dry sheet (1b) of the first panel, but it is not sufficiently conducted or irradiated towards the first dry sheet (1a) of the same first panel (1), and the outside, so that temperature loss is largely avoided and a very good efficiency of this type of collector is achieved.

ADVANTAGES OF THE INVENTION

The main advantages of this design, is its great efficiency, because although the plastic material does not have good thermal conductivity, it has a high rate of heat absorption, in this system, the total surface area of the panel, since each square centimeter of the panel (2) that is exposed to solar radiation, is in contact with the fluid inside and the thickness of the panel wall, for the exchange is only a fraction of a millimeter. Therefore, it is carried out in a homogeneous, fast and efficient way. Another advantage is that due to the lightness of the panels, the finished collectors are easy to transport and their installation is simplified in high places, such as roofs and sloping slabs, in addition to being plastic panels, they resist without problem the hail blows, or small tree branches or stones and also allows to be easily manipulated during transport without risk of breaking. The materials necessary for its manufacture are easy to obtain and assemble, these collectors can be interconnected in parallel or in series by means of union nuts or any known means and thus achieve large catchment surfaces for larger projects. The useful life of these collectors can be greater than 10 years, since the plastic panel is guaranteed by the manufacturer, of course, that this depends on the type of fluid that circulates inside, which can be water and heat it directly or by means of a fluid, such as antifreeze, which if circulated through an exchanger, can heat the water, thus preventing possible damage due to blockage by tartar of the cells or rupture in case of frost and freezing.

APPLICATION OF THE INVENTION

To exemplify the functionality of the present invention, the following notes obtained from tests performed are presented:

A maximum temperature test was carried out, where a small panel with an aluminum frame was assembled to which a thermal panel was placed at the back and covered by the upper part with a transparent cellular plastic panel, and inside A black plastic laminate was placed, forming a heat chamber. Placing this small panel towards the sun, temperatures were obtained up to 100 ° C in the interior air environment of the chamber, and the temperature on the outer face of the sheet of the roof was about 70 ° C and on the black sheet from inside the temperature rose to 118 ° C, of course, without containing fluid inside, this differential of more than 35 ° C between the inside of the heat chamber and the outside of the cover panel, indicates that the Poly-carbonate cellular laminate material works as a thermal barrier, efficient and that in theory, could be improved, achieving a vacuum inside the cells or injecting some inert gas inside, although this would raise the cost of the equipment and taking into account that, one of the main principles, for what was carried out This project is the economy of the same and that with the efficiency that is being achieved with the current procedure, that is, with air in the dry chambers, it is sufficient to achieve temperatures in the fluid of up to 90 ° C for what not It is considered necessary to do these processes trying to improve even more the efficiency already achieved. This test, indicates that the basic principle of the system, forming a heat chamber with a cellular plastic panel as a cover, a thermal panel as a backrest and a black plastic laminate inside, all framed by an aluminum profile in Channel form with thermal protection, it is a system where high temperatures can be achieved and can be used to heat fluids, with great efficiency, achieving a very simple system, easy to manufacture and with a cost well below existing systems. This test was performed in the city of León Guanajuato Mexico at an ambient temperature of 30 ° c. With weak winds.

Claims

CLAIMS. 1. Solar collector for fluids, comprising a frame formed by four channel-shaped stringers joined together by their ends; said frame has in its upper part, a transparent cover and in its back a base of thermal plate; inside a heat exchanger, with fluid inlet and outlet tubes, arranged on the basis of thermal plate; Characterized in that the transparent cover is formed by a plastic panel comprising a first dry sheet joined to a second dry sheet by means of longitudinal ribs that define a plurality of dry channels; The heat exchanger is formed by a black plastic panel, comprising a first wet sheet joined to a second wet sheet by longitudinal ribs defining a plurality of wet channels; where the fluid inlet and outlet tubes have a longitudinal groove with seal, in which the wet panel is inserted, keeping both tubes fluid communication with the channels of the panel; a sealed chamber defined between the second dry sheet and the first wet sheet, forming a heat chamber. 2. Solar collector for fluids in accordance with clause 1. Also characterized in that the dry panel channels can be arranged transversely with respect to the wet panel channels. 3. Solar collector for fluids in accordance with clause 1. Also characterized in that the fluid inlet and outlet tubes are arranged transversely with respect to the wet panel channels. 4. Solar collector for fluids in accordance with clause 1. Also characterized in that the edges of the wet panel are beveled in "V", defining an angle that allows the outlet for the liquid 5. Solar collector for fluids in accordance with clause 1. Also characterized in that the transparent cover and the heat exchanger are made of cellular laminated plastic. 6. Solar collector for fluids in accordance with clause 1. Also characterized in that the channels of the roof can contain air or inert gas. 7. Solar collector for fluids in accordance with clause 1. Also characterized in that the heat exchanger is made of black plastic laminated plastic. 8. Solar collector for fluids in accordance with clause 1. Also characterized in that the space that forms the heat chamber can contain air or inert gas.