FR2942029A1 - Thermal solar collector for use on facade of building, has vanes transmitting partially detected calorific energy to heat-transfer fluid circulating in heat-transfer fluid duct, and gas or air volume partitioned between walls - Google Patents

Abstract

The collector (1) has multiple opaque vanes (5) arranged between translucent front wall and a rear wall for receiving solar rays, where the vanes are inclined with respect to the walls. A heat-transfer fluid duct is arranged between the walls, and vanes are connected on portions of the duct. The vanes transmit partially detected calorific energy to heat-transfer fluid circulating in the heat-transfer fluid duct. Gas or air volume (8) is partitioned between the walls, where the rear wall is opaque. The vanes are extended along predetermined orientation. An independent claim is also included for a thermal installation comprising a storing reservoir.

Description

The present invention relates to a solar thermal collector and a thermal installation comprising such a sensor. A solar thermal collector converts solar energy into heat that can be recovered for heating or hot water supply.

It is known that a sensor is formed of a translucent front wall, for example a glass pane, and a rear wall jointly forming a solar panel. In a known manner, a heat transfer fluid is heated by passing through a serpentine pipe disposed behind the window. Once the heated fluid, a circulator can convey the fluid out of the solar collector to a tank or heat exchanger for recovering the calories stored by the heat transfer fluid. This type of installation therefore requires an external power supply to power the circulator and the associated control electronics. In addition, the efficiency of these sensors is highly dependent on the orientation of the panel relative to the inclination of the sun, which generally limits their installation on sloping roofs of buildings that must be oriented to the south. It is also possible to install sensors directly on the ground or on the terrace on an inclined support. The inclination of the support is generally equal to 45 ° in France to have a maximum luminous flux which crosses the glass surface. However this type of installation is not aesthetic and requires a substantial occupation area that can not be used for other effects. The present invention aims to solve all or part of the disadvantages mentioned above.

For this purpose, the present invention relates to a solar thermal collector comprising a translucent front wall and a rear wall jointly forming a solar panel, characterized in that it comprises a plurality of opaque fins disposed between said walls and intended to receive a solar radiation for capturing its heat energy, the fins being inclined relative to the walls, a coolant pipe disposed between the walls and having a plurality of portions on which are reported the fins, the fins being intended to transmit at least one part of the heat energy they have captured to the coolant circulating in said pipe, and a volume of air or gas partitioned between said walls, and in that the rear wall is opaque.

These arrangements and in particular the inclination of the fins allow easy mounting vertically of a solar collector on the facade of a building facing south, while ensuring satisfactory efficiency of the solar collector.

The substitution of conventional solar collectors placed on the roof can be considered in particular for aesthetic reasons desired by the client, or by the Architects of Buildings of France. This substitution is also desirable in the case of poorly oriented roofs or commonly snow-covered roofs, for example in mountainous areas.

The fact that the fins are supported directly by the portions of the pipe also gives a better performance from the heat conduction to the heat transfer fluid of the heat energy from solar radiation and stored by the fins. In addition, because the rear surface is opaque, the latter behaves like a black body that re-emits solar radiation over a large part of its spectrum, particularly in the infrared. This infrared radiation is intercepted directly by the pipe and the rear part of the fins which further improves the heating and therefore the efficiency of the solar collector.

Partitioning a volume of air or gas inside the panel limits the heat loss inside the panel. Indeed, this partitioning generates a thermosiphon which by thermal convection keeps the hottest gases on the upper part of the panel, which decreases the thermal gradient between the pipe and the walls. The convection movements inside the panel can also be improved by profiling the end of the fins. A thermosiphon is also created inside the coolant pipe which naturally convects the hottest heat transfer fluid parts up the pipe.

This gives a double thermosiphon system allowing the natural circulation of the heat transfer fluid, while limiting the heat losses. Finally, the partitioning of air or gas also provides an additional layer of insulation to the facade of the building where the panels are installed.

This type of solar collector can therefore be used when the building has a blind south wall, an available south wall location, or when architects want sensors designed for contemporary homes or for industrial buildings, etc. . Advantageously, the coolant pipe has a general shape of coil.

According to one embodiment, the fins extend in a predetermined orientation. In another variant, the inner surface of the rear wall is able to absorb at least a portion of the heat energy from solar radiation, and is preferably black.

According to another embodiment, the pipe comprises at these ends connectors, each connection being intended to be connected to a connection of an adjacent solar collector. These arrangements make it possible to connect several solar collectors together in order to increase the heating surface.

These solar collectors are therefore in their industrial application, integrated into a thermal installation comprising at least one of these sensors. This installation allows circulation of the heat transfer fluid in order to recover the useful heat to the different needs of the occupants of the building.

According to one embodiment, this installation comprises a storage tank. This reservoir stores the calories supplied by the heat transfer fluid. The tank generally contains a heat exchanger which in turn recovers the calories stored in the tank to heat sanitary water or other heat transfer fluid circulating in the heating circuit of the building. According to one possibility, the storage tank is located at a height higher than said solar collector. This provision alone is sufficient to convectively circulate the coolant whose hottest parts back through the installation to the tank. According to one embodiment, the installation comprises a low pressure circulator for improving the circulation of the coolant. Advantageously, the low-pressure circulator is powered by a photovoltaic solar collector or any other renewable energy source such as a wind turbine for example. According to another embodiment, the installation comprises a high-pressure circulator. This arrangement forces the circulation of heat transfer fluid and it is therefore no longer necessary to restrict the position of the reservoir to a height greater than that of the sensor or sensors. Advantageously, a plurality of solar collectors are mounted in battery, this allows a simple installation and adapted to the facade. Indeed, it is possible to assemble between them panels of different widths with the help of termination connectors, which makes it possible to adapt to the facade in the presence and to realize quasi-custom installations. Finally, in another embodiment, the connections between the pipes of each sensor are connected by welding in order to increase the service life of the system and to prevent leakage of the coolant. The invention will be better understood with the aid of the description which follows, with reference to the appended schematic drawing showing, by way of non-limiting example, several embodiments of this solar collector. Figure 1 is a front view of a solar thermal collector according to the invention. Figure 2 is a sectional side view of a solar collector 20 according to the invention. FIG. 3 represents a first mode of implementation of a thermal installation integrating a solar collector according to the invention. FIG. 4 represents a second mode of implementation of a thermal installation integrating a solar collector according to the invention. FIG. 5 represents a third embodiment of a thermal installation incorporating a solar collector according to the invention. According to the invention and as illustrated in FIG. 2, the solar thermal collector 1, intended to be mounted vertically on the facade of a building, comprises a translucent front wall 3 generally made of glass and an opaque rear wall 4. These two walls are parallel and together form a panel 2. The rear wall 4 comprises an inner sheet 4a and an outer sheet 4b between which there is an insulator 4c limiting air movements between the two sheets. Between the front wall 3 and the rear wall 4 there is arranged a coolant pipe 6 made preferably of copper. The pipe 6 has a generally serpentine shape in order to increase the heating surface of the coolant by the sun's rays. The heat transfer fluid used is advantageously glycol water to prevent any risk of freezing in winter. The pipe 6 comprises cylindrical support portions 7 on which are fixed a plurality of fins 5 by elastic interlocking as shown in FIG. 2. Each fin 5 comprises two flat surface portions interconnected by a third shaped portion. of U which fits on a support portion 7 of the pipe 6. The fixing of each fin by the U-shaped portion allows a rotation of each fin relative to the pipe 6, and therefore a tilt adjustment of each fin according to the axis of symmetry of the corresponding support portion 7. The ends of the two flat surface portions are contoured to promote convective motions of a volume of air or gas partitioned between the walls 3,4 of the panel. The sun's rays penetrate inside the solar collector 1 through the glazed front wall 3 of the latter. Some of these spokes 20 then meet the fins 5 disposed on the portions 7 of the pipe 6. These portions 7 are preferably horizontal so as to give a suitable orientation to the fins 5, in order to have a maximum of luminous flux from the radii of the sun. The optimum angle of inclination of the fins 5 to capture a maximum of solar radiation usually corresponds to the latitude of the place where the solar collector 1 is installed. In France, it is typically 45 °. However, to avoid overheating in summer, this angle is preferably reduced to 60 °. For this purpose, the inclination of the fins in the device is adjustable from 45 to 60 ° depending on the end use and the geographical location. In addition, the fins 5 are made in one piece in a material that is a good conductor of heat, such as aluminum. Aluminum has the property of reflecting a part of the radiation which remains trapped inside the panel 2 by multiple reflection on the walls. This greenhouse-entrapped radiation contributes to the warming of the interior of the panel 2.

Other solar rays directly meet the inner sheet 4a of the rear wall 4. The warming of the panel is further increased by the properties of this inner sheet 4a of the rear wall 4. This inner sheet has a black surface which absorbs a maximum of solar radiation. This absorption causes a heating of this sheet 4a which then behaves like a black body. This black body will re-emit on a part of the spectrum especially in the wavelengths corresponding to long infrared. These long infrared are re-emitted by the black body towards the front wall 3 of the solar collector where they are reflected by the glass surface in the direction of the fins 5. They are therefore confined inside the panel 2. They can also be directly intercepted by the rear wall of the different fins, in which case they contribute to the heating thereof. These various heating means also contribute to the heating of the air or gas 8 confined inside the panel 2. This air or gas 8 will move by convection inside the panel 2 thus establishing the parts the warmest air or gas 8 at the top of the panel and the colder parts at the bottom of the panel. This has the effect of creating a natural thermosiphon inside the panel 2 of the sensor 1: the air on the side of the colder transparent wall 3 will tend to go down while the air is on the side of the wall Rear 4 of a higher temperature will tend to rise by convection, as shown by the arrows representing the movements of air inside the panel 2 of the sensor 1 in FIG.

By all these means, the heat transfer fluid is thus heated inside the pipe 6. Figure 3 shows a thermal installation 9 according to a first embodiment. The thermal installation 9 comprises a storage tank 10 and several battery-mounted sensors 21 interconnected. The various sensors and the reservoir form a primary circuit 16 inside which circulates the coolant. The solar collector 1 with its heat transfer fluid pipe 6 is thus part of an installation 9 comprising other battery-mounted panels 21 and a storage tank 10 located inside the building which coupled to a heat exchanger 15 recovers the calories passing through the primary circuit 16 for transmission to a secondary circuit 17 hot water distribution. The thermal installation 9 is a completely antifreeze and self-regulating system. The panels 2 are arranged in battery 21 by means of connectors 14 located laterally on either side of the ends of the duct 6 of each panel 2. In order to prevent any leakage of heat transfer fluid caused by loose fittings 14, it is it is preferable to weld together the various connectors 14 connected during the installation of the panels 2. It is also possible to tailor the battery 21 of 10 panel 2 to the width of the building facade by having panels 2 of different widths on the facade. According to this first embodiment shown in Figure 3, the heat transfer fluid circulates naturally by convection inside the pipes of the various solar collectors. In fact, the hottest heat transfer fluid parts are less dense than the colder parts and therefore go up by convection inside the primary circuit 16 of the installation 9. The storage tank 10 is placed at a height higher than that of the solar collectors 1. The hottest parts of the fluid are therefore discharged from the sensors 1 from the top of the pipes 6 towards the storage tank 10 while the colder parts go through the bottom of the pipes 6 in the sensors 1. A double thermosiphon is thus obtained on the one hand for the convection movements of the coolant in the pipes 6, and on the other hand for the movements of air or gas 8 in the panels 2. installation 9 is perfectly autonomous and self-regulating. It requires no control electronics or external energy input for the circulation of the heat transfer fluid. For this purpose, it may for example be used in remote isolated sites or sites with no connection to the power grid. In a second embodiment shown in FIG. 4, the installation further comprises a low-pressure circulator 11 to assist in the circulation of the coolant. To maintain the autonomy of the installation 9, the circulator 11 is powered via a photovoltaic solar collector 12 or other renewable energy source, such as a wind turbine. However, the photovoltaic solar collector 12 has an advantage because it does not require a control system. In fact, the more sun there is, the more the solar collectors 1 heat the heat transfer fluid, but also the solar photovoltaic collector 12 produces current to supply the circulator 11, which rotates the faster it is powered. In a third embodiment shown in FIG. 5, the storage tank 10 is placed at any height relative to the solar collectors 1. It can therefore be at a height that is lower than that of the sensors 1, which requires the use of a high pressure circulator 13 with its associated control system. The circulator 13 is powered by the electrical network, temperature probes 18 are conveniently placed on the primary circuit 16 of the installation 9. These probes 18 are connected to a regulator 19 and provide an indication of the temperature of the coolant in two points of the primary circuit 16 of the installation 9 taken upstream and downstream of the battery 21 of panels 2 of solar collectors 1. By these measurements, the thermal gradient is deduced inside the ducts 6 of the battery 21 of panels 2 of solar collectors 1, then it is compared to a value preprogrammed in the regulator 19. If the measured gradient is below this preprogrammed value then the regulator 19 will start the high pressure circulator 13 until a gradient is obtained. satisfactory. If the measured gradient is above the preprogrammed value then the regulator 19 will not feed the circulator 13 and will wait for the sun to heat the coolant in the sensors 1 to be able to feed it. This heating will have the consequence of reducing the thermal gradient in the sensors 1 and the regulator 19 will then actuate the high pressure circulator 13 to discharge the heat transfer fluid to the hot storage tank 10. In this embodiment, it may be necessary to couple the regulator 19 to a clock system 20 so that the high-pressure circulator 13 does not trip during the night. Indeed, during the night the heat transfer fluid is no longer heated and the temperature of the heat transfer fluid in the pipe 6 is leveling to its low value. The thermal gradient in the solar collector 1 decreases, which triggers the startup of the circulator 13. Therefore, it is necessary to use a clock system 20. This clock system 20 may be constituted by a simple clock indicating the hours of the day or by a photovoltaic sensor indicating satisfactory sunshine for the start of the solar thermal collector 1.

As goes without saying, the invention is not limited to the embodiments of this solar thermal collector, described above as examples, but it encompasses all variants.5

Claims (13)

REVENDICATIONS1. Thermal solar collector (1) comprising a translucent front wall (3) and a rear wall (4) jointly forming a solar panel (2), characterized in that it comprises: - a plurality of opaque fins (5) arranged between said walls (3, 4), intended to receive solar radiation in order to capture its heat energy, the fins being inclined with respect to the walls (3, 4), a conduit (6) of coolant disposed between the walls (3) , 4) and having a plurality of portions (7) on which the fins (5) are attached, the fins (5) being intended to transmit at least a portion of the heat energy that they have captured to the coolant flowing in said duct (6), - a volume of air or gas (8) partitioned between said walls (3,4), and in that the rear wall (4) is opaque. 2. solar thermal collector (1) according to claim 1 wherein the pipe (6) of heat transfer fluid has a general shape of coil (6). 3. Solar thermal collector (1) according to one of the preceding claims wherein the fins (5) extend in a predetermined orientation. 4. solar thermal collector (1) according to one of the preceding claims wherein the inner surface (4a) of the opaque rear wall (4) is adapted to absorb at least a portion of the heat energy from solar radiation, and is preferably black in color. 5. Solar thermal collector (1) according to one of the preceding claims wherein the pipe (6) comprises at these ends connectors (14), each connection (14) being intended to be connected to a connector (14). an adjacent solar collector. 6. Thermal plant (9), characterized in that it comprises at least one solar thermal collector (1) according to one of the preceding claims. The thermal plant (9) of claim 6 which comprises a storage tank (10). 8. Thermal plant (9) according to claim 7 wherein the storage tank (10) is located at a height higher than said solar collector (1). 9. Thermal plant (9) according to one of claims 6 to 8 5 which comprises a low pressure circulator (11). 10. Thermal plant (9) according to claim 9 wherein the low pressure circulator (11) is powered by a photovoltaic solar collector (12) or other renewable energy source. 11. Thermal plant (9) according to one of claims 6 to 8 10 which comprises a high pressure circulator (13). 12. Thermal plant (9) according to one of claims 6 to 11 wherein a plurality of solar thermal collectors (1) are mounted in battery (21). 13. Thermal plant (9) according to one of claims 6 to 12 15 wherein the connections (14) between the pipes (6) of each solar collector (1) are connected by welding.