Expanded and compressed graphite panel for thermal energy storage and heat storage and exchange device incorporating such a panel

Abstract

One aspect of the invention relates to an expanded and compressed graphite panel 1, referred to as the GNE panel, for thermal energy storage, the GNE panel 1 being impregnated with a phase-change material, the GNE panel 1 being notable in that it comprises a plurality of impregnation orifices 2 for the entry of the phase-change material during liquid-phase impregnation of the phase-change material, each impregnation orifice 2 having a longitudinal axis X perpendicular to a compression plane P of the GNE panel 1. Figure to be published with the abstract: Figure 1

Description

Title of the invention: EXPANDED AND COMPRESSED GRAPHITE PANEL FOR THERMAL ENERGY STORAGE AND HEAT STORAGE AND EXCHANGE DEVICE COMPRISING SUCH A PANEL. TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to an expanded and compressed graphite panel, referred to as a GNE panel, for the storage of thermal energy, in other words, heat or cold, and a heat storage and exchange device equipped with at least one such GNE panel. The invention therefore relates to the technical field of thermal energy storage. TECHNOLOGICAL BACKGROUND OF THE INVENTION

[0002] In order to store thermal energy for later use, it is known to store thermal energy in sensible form in water. However, such thermal energy storage is limited in both temperature and pressure. This pressure limit is imposed by the pressure of the water distribution network and the permissible pressure of the water storage tank.

[0003] Thermochemical storage is also known. However, such storage requires the use of storage vessels whose pressure must be controlled and whose media disintegrate over time.

[0004] The storage of latent thermal energy within a heat storage material is also known. Document WO1998004644A1 discloses, for example, a material comprising, on the one hand, a compressed expanded graphite matrix and, on the other hand, a phase-change material as a heat storage medium. The phase transition of the heat storage material can occur by passing between solid-solid, liquid-liquid, or solid-liquid states. The graphite matrix is ​​particularly impregnated with a phase-change material by immersing the graphite matrix in the phase-change material in the liquid phase.

[0005] Such impregnation is not optimized, however, so that the matrix contains a limited amount of phase-change material compared to its impregnation capacity. Summary of the invention

[0006] The invention offers a solution to the problem mentioned above, by proposing an expanded and compressed graphite panel allowing the impregnation of a significant amount of phase change material.

[0007] In this context, the invention thus relates, in its broadest sense, to an expanded and compressed graphite panel, called a GNE panel, for the storage of thermal energy, the GNE panel being impregnated with a phase change material.

[0008] The GNE panel according to this aspect of the invention is remarkable in that it comprises a plurality of impregnation orifices for the entry of the phase change material during a liquid phase impregnation of said phase change material, the impregnation orifices comprising a longitudinal axis perpendicular to a compression plane of the GNE panel.

[0009] Thus, when the GNE panel is immersed in a bath of phase change material, the impregnation orifices facilitate the evacuation of gases and the entry of the phase change material in liquid phase during impregnation.

[0010] In addition, since the impregnation holes are drilled perpendicular to a compression plane of the GNE panel, the phenomenon of delamination of the GNE panel is avoided.

[0011] In addition to the characteristics which have just been mentioned in the preceding paragraph, the GNE panel according to this aspect of the invention may have one or more complementary characteristics from among the following, considered individually or according to all technically possible combinations.

[0012] According to a non-limiting aspect of the invention, it comprises a plurality of sealing elements, each impregnation orifice being sealed by a sealing element.

[0013] Thus, when the GNE panel is in operation, the sealing elements make it possible to reduce leakage of the phase change material impregnated in the GNE panel.

[0014] According to a non-limiting aspect of the invention, the GNE panel is formed of several expanded and compressed graphite strips, the strips being arranged side by side so as to form a parallelepiped panel, at least one of the strips having a compression plane perpendicular to at least one compression plane of one of the other strips.

[0015] A different aspect of the invention relates to a method of impregnating a GNE panel according to any one of the aspects of the above-mentioned invention, said method comprising a step of impregnating the GNE panel during which the GNE panel is placed vertically in a bath of liquid phase-change material, one end of the GNE panel emerging from the bath during said impregnation step.

[0016] Another aspect of the invention relates to a heat storage and exchange device comprising a heat storage and exchange assembly equipped with: • Of a first GNE panel according to any one of the aforementioned aspects of the invention; • From a first flat heat exchanger having a first heat exchange surface in contact with a first main surface of the GNE panel.

[0017] According to a non-limiting aspect of the invention, the device comprises: • A first retaining plate in contact with a second main surface of the first GNE panel parallel to the first main surface; • A plurality of rods, each rod being inserted into a retaining orifice passing through the heat storage and exchange assembly and the first retaining plate, one end of each of said rods being welded to the first flat-plate heat exchanger and the other end of each of said rods having a head in contact with a spring element, the spring element being disposed between the head and the first retaining plate.

[0018] According to a non-limiting aspect of the invention, the first retaining plate is formed by a second flat-plate heat exchanger.

[0019] According to a non-limiting aspect of the invention, the heat storage and exchange assembly further comprises a second GNE panel, the first flat heat exchanger having a second heat exchange surface in contact with a first main surface of the second GNE panel parallel to the first main surface of the first GNE panel, the device further comprising: • A first retaining plate in contact with a second main surface of the first GNE panel parallel to the first main surface of the first GNE panel; • A second retaining plate in contact with a second main surface of the second GNE panel parallel to the first main surface of the second GNE panel; • A plurality of rods, each rod being inserted into a retaining orifice through the heat storage and exchange assembly and the first and second retaining plates, one end of each rod being welded to the second metal plate and a second end of each rod having a head in contact with a spring element, said spring element being disposed between the head and the first retaining plate.

[0020] According to a non-limiting aspect of the invention, the heat storage and exchange assembly further comprises a second flat-plate heat exchanger having a first heat exchange surface in contact with a second heat exchange surface of the first flat-plate heat exchanger, the device further comprising: • A first retaining plate in contact with a second main surface of the first GNE panel parallel to the first main surface of the first GNE panel; • A plurality of rods, each rod being inserted into a retaining orifice through the heat storage and exchange assembly and the first retaining plate, one end of each rod being welded to the second flat heat exchanger and a second end of each rod having a head in contact with a spring element, said spring element being disposed between the head and the first retaining plate.

[0021] According to a non-limiting aspect of the invention, each retaining orifice is provided in a slat whose compression plane is perpendicular to the longitudinal axis of the retaining orifice.

[0022] According to a non-limiting aspect of the invention, each flat heat exchanger is formed of a flat heat exchange plate and an embossed heat exchange plate placed one on top of the other and forming between them at least one conduit for conveying a heat transfer fluid.

[0023] According to a non-limiting aspect of the invention, a filler product having a thermal conductivity greater than 6 W / m / K is disposed between: • A GNE panel and a flat plate heat exchanger; and / or • A GNE panel and a retaining plate.

[0024] According to a non-limiting aspect of the invention, the filler product is formed by grinding and compacting a GNE panel mixed with: • A contact grease; • A thermal grease; • A mixture of alloy; or • A mixture of metals.

[0025] According to a non-limiting aspect of the invention, the device comprises a heating element disposed in contact with a GNE panel or with a GNE panel and a flat plate heat exchanger. The heating element is, for example, of the electric type and uses the Joule heating principle.

[0026] According to a non-limiting aspect of the invention, at least one GNE panel is arranged in a vacuum envelope.

[0027] According to one embodiment, the stock comprises GNE panels placed in vacuum envelopes, which are themselves placed between two sheets with a sealed perimeter forming a vacuum enclosure.

[0028] Another aspect of the invention relates to a heat storage and exchange system comprising: • A heat transfer fluid delivery circuit equipped with at least two pipes connected in parallel, each pipe being equipped with a solenoid valve arranged to allow or prohibit the circulation of a heat transfer fluid in said pipe, one of the at least two pipes comprising a heat storage and exchange device according to any one of the aforementioned aspects of the invention; • A device for measuring the temperature of a heat transfer fluid circulating in the circuit; • Control means, the control means being arranged to control the solenoid valves according to a temperature of the heat transfer fluid measured by the temperature measurement device.

[0029] According to a non-limiting aspect of the invention, each pipe is further provided with a second solenoid valve, one of said two solenoid valves of a pipe being disposed at the inlet of said pipe and the other of said two solenoid valves of said pipe being disposed at the outlet of said pipe, said two solenoid valves of a pipe being arranged to allow or prohibit the circulation of a heat transfer fluid in said pipe.

[0030] A different aspect of the invention relates to a method for controlling a heat storage and exchange system as described above, the method being notable in that it comprises the steps of: • Measure the temperature of the heat transfer fluid using the temperature measuring device; • Depending on the measured temperature of the heat transfer fluid, • To control the opening, via the control means, of one or two solenoid valves in a pipe so as to allow circulation of the heat transfer fluid in the pipe associated with said open solenoid valve(s), and • Control the closure, via the control means, of one or two solenoid valve(s) of another pipe so as to prohibit circulation of the heat transfer fluid in said other pipe associated with said closed solenoid valve(s).

[0031] The invention and its various applications will be better understood by reading the following description and examining the accompanying figures. BRIEF DESCRIPTION OF THE FIGURES

[0032] [Fig.1] illustrates a three-dimensional view of an example of an embodiment of an expanded and compressed graphite panel according to the invention.

[0033] [Fig.2] shows a cross-sectional view of a portion of the expanded graphite panel and compressed illustrated in [Fig.1].

[0034] [Fig.3a], [Fig.3b] illustrate other non-limiting examples of an embodiment GNE panel according to the invention.

[0035] [Fig.4] shows a first example of the realization of a storage device and heat exchange according to the invention.

[0036] [Fig.5] illustrates a second example of the embodiment of a storage device and heat exchange according to the invention.

[0037] [Fig.6] illustrates a third example of the embodiment of a storage device and heat exchange according to the invention.

[0038] [Fig.7] illustrates a fourth example of the embodiment of a storage device and heat exchange according to the invention.

[0039] [Fig.8] illustrates a fifth example of the embodiment of a storage device and heat exchange according to the invention.

[0040] [Fig.9] illustrates a sixth example of the embodiment of a storage device and heat exchange according to the invention equipped with an electric heating element using the principle of heating by joule effect.

[0041] [Fig. 10] illustrates a GNE panel arranged in a vacuum envelope.

[0042] [Fig. 11] illustrates a heat storage and exchange system according to the invention.

[0043] [Fig. 12] illustrates an example of the implementation of a method for controlling a system heat storage and exchange such as that illustrated in [Fig. 11] allowing a heat transfer fluid to be cooled by transferring heat from the heat transfer fluid to heat storage and exchange devices.

[0044] [Fig. 13] illustrates another example of the implementation of a method for controlling a heat storage and exchange system such as that illustrated in [Fig. 11] allowing the heat transfer fluid to be heated by a transfer of heat from the heat storage and exchange devices to the heat transfer fluid.

[0045] [Fig. 14] illustrates a heat storage and exchange system according to another example of the invention.

[0046] [Fig. 15] illustrates a method of impregnating a GNE panel according to the invention. DETAILED DESCRIPTION

[0047] The figures are presented for illustrative purposes only and are not in any way limiting to the invention.

[0048] Unless otherwise specified, the same element appearing on different figures has a unique reference.

[0049] Fig. 1 illustrates a three-dimensional view of an example of an embodiment of an expanded and compressed graphite panel 1, referred to as the GNE panel, according to the invention.

[0050] The GNE 1 panel is impregnated with a phase change material and has a plurality of impregnation orifices 2 for the entry of the phase change material during a liquid phase impregnation of the phase change material.

[0051] As illustrated in [Fig.2] showing a cross-sectional view of a portion of the GNE 1 panel, the impregnation holes 2 have a longitudinal axis X perpendicular to a compression plane P of the GNE 1 panel.

[0052] These impregnation orifices 2 may be open or closed. They may also be conical, cylindrical, or parallelepiped in shape. These impregnation orifices 2 facilitate the evacuation of gases and the entry of the phase-change material into the liquid phase during impregnation.

[0053] According to a non-limiting embodiment, the impregnation holes 2 can be cylindrical, pass through the thickness E of the GNE 1 panel and have a diameter between 1 and 2 mm.

[0054] By way of non-limitation, the impregnation holes 2 can be drilled according to a perpendicular grid and spaced from each other by a distance d of the order of 20 mm.

[0055] According to a non-limiting embodiment, the GNE 1 panel has a thickness E of 30 mm.

[0056] As illustrated in [Fig.2], each impregnation orifice 2 can be sealed by a sealing element 3.

[0057] For example, when the impregnation orifices 2 have a circular cross-section, the sealing elements 3 can be formed by hollow cylinders inserted into the impregnation orifices 2 following an impregnation operation of the phase-change material. The sealing elements 3 help to reduce leakage of the impregnated phase-change material into the GNE panel 1 when the GNE panel is in operation.

[0058] Figures 3a, 3b, illustrate other non-limiting examples of embodiments of a GNE 1 panel according to the invention.

[0059] According to these embodiments, the GNE 1 panel is formed of several expanded and compressed graphite flakes 4 impregnated with a phase-change material. Only four flakes are illustrated. The flakes 4 are arranged side by side so as to form a parallelepiped-shaped GNE 1 panel in which two of the four flakes 4 have a compression plane P perpendicular to the compression plane P of the other two flakes 4.

[0060] More specifically, as illustrated in [Fig. 1], the GNE 1 panel has compression planes P perpendicular to the compression that was carried out to It is manufactured from natural graphite exposed to a thermochemical treatment. The thermal conductivity along the compression planes P, symbolized by lines perpendicular to the thickness E of the GNE 1 panel, is approximately three times greater than perpendicular to these compression planes P.

[0061] Thus, according to the embodiments illustrated in Figures 3a and 3b, the GNE 1 panel shown in [Fig. 1] is cut into strips 4 of a width equal to its thickness E. In order to improve the thermal conductivity of the GNE 1 panel, some of the strips 4 are rotated by 90°. Those that are not rotated are used for the subsequent fixing of the GNE 1 panel to a flat plate heat exchanger.

[0062] Fig. 4 illustrates a heat storage and exchange device 5 comprising a heat storage and exchange assembly 6.

[0063] The heat storage and exchange assembly 6 is equipped with a GNE 1 panel such as that illustrated in [Fig.1] and a flat heat exchanger 7. The flat heat exchanger 7 has a first heat exchange surface 8i in contact with a first main surface 9i of the GNE 1 panel. By main surface, we mean one of the two surfaces of the GNE 1 panel whose area is the largest.

[0064] According to a non-limiting embodiment, the flat heat exchanger 7 is formed of a flat heat exchange plate 10 and an embossed heat exchange plate 11 placed one on top of the other and forming between them at least one conduit 12 for conveying a heat transfer fluid. The flat and embossed heat exchange plates 10, 11 may be welded together.

[0065] According to a non-limiting embodiment, the flat heat exchanger 7 has a thickness of 6 mm.

[0066] The heat storage and exchange device 5 further comprises a retaining plate 13 in contact with a second main surface 92 of the panel GNE1. The second main surface 92 of the panel GNE1 is parallel to the first main surface 9i of the panel GNE1.

[0067] In other words, the planar heat exchanger 7 and the retaining plate 13 are arranged on either side of the GNE 1 panel.

[0068] The heat storage and exchange device 5 further comprises a plurality of rods 14 (only one is shown) for holding the panel GNE 1, the flat heat exchanger 7 and the retaining plate 13.

[0069] According to a non-limiting embodiment, each rod 14 has a diameter of 3mm.

[0070] Each rod 14 is inserted into a retaining hole 15 with longitudinal axis X perpendicular to the compression plane P, for example with a diameter of 8 mm, passing through the assembly 6 and the retaining plate 13. A first end 16 of each of the rods 14 is welded to the planar heat exchanger 7 and a second end 17 of each of the rods 14 has a head 18 in contact with a spring element 19.

[0071] The head 18 can be formed by a washer welded to the rod 1. Such a washer can, for example, have a diameter of 25mm.

[0072] The spring element 19 is arranged between the head 18 and the retaining plate 13 so as to keep the panel GNE 1 in contact with the flat heat exchanger 7.

[0073] The retaining plate 13 is formed, for example, by an aluminum sheet placed in contact with the panel GNE 1 and below the spring element 19. It thus prevents the spring element 19 from penetrating inside the panel GNE 1. The spring element 19 also allows to absorb the changes in thickness E of the panel GNE 1 generated by changes in temperature.

[0074] In the illustrated example, the spring element 19 is integrated into the retaining plate 13. More specifically, the retaining plate 13 is formed by a flexible metal plate having flexible deformations on its surface obtained by cutting or stamping. These flexible deformations are arranged under the heads 18 and act as springs so as to press the panel GNE 1 against the flat heat exchanger 7.

[0075] The spring element 19 is dimensioned so as to exert a force enabling the panel GNE 1 to remain in contact with the flat heat exchanger 7, despite the expansion of the graphite under the effect of heat and the expansion of the phase change material during its phase change.

[0076] In different embodiments, the spring element 19 can be integrated into the head 18 or be independent of the retaining plate 13 and the head 18.

[0077] Fig. 5 illustrates a heat storage and exchange device 5 conforming to that illustrated in Fig. 4, in which the retaining plate 13 is replaced by a second flat heat exchanger 7. In this case, each flat heat exchanger 7 is formed of a flat heat exchange plate 10 and an embossed heat exchange plate 11 placed one on top of the other and forming between them at least one conduit 12 for conveying a heat transfer fluid.

[0078] For example, the conduit 12 for conveying a heat transfer fluid from one of the two planar heat exchangers 7 is arranged to transmit heat from the conduit to the panel GNE 1 and the conduit 12 for conveying a heat transfer fluid from the other of the two planar heat exchangers 7 is arranged to absorb heat from the panel GNE 1.

[0079] According to the non-limiting example shown, each spring element 19 is formed by a compression spring disposed between a head 18 of a rod 14 and the second flat heat exchanger 7.

[0080] Fig. 6 illustrates a heat storage and exchange device 5 comprising three heat storage and exchange units 6 equipped with a first panel GNE 1 and a second panel GNE 1 such as that illustrated in Fig. 1 and a flat heat exchanger 7. The first panel GNE 1 and the second panel GNE 1 being arranged on either side of the flat heat exchanger 7.

[0081] The three heat storage and exchange units 6 are stacked one on top of the other.

[0082] Each planar heat exchanger 7 has a first heat exchange surface 8i in contact with a first main surface 9i of the first GNE 1 and a second heat exchange surface 82 in contact with a first main surface 9i of the second panel GNE 1.

[0083] The heat storage and exchange device 5 further comprises a first retaining plate 13 in contact with a second main surface 92 of a first panel GNE 1 located at one end of the stack.

[0084] The heat storage and exchange device 5 further includes a second retaining plate 13 in contact with a second main surface 92 of a second panel GNE 1 located at the other end of the stack.

[0085] In other words, the first and second retaining plates 13 are arranged on either side of the stack of the three heat storage and exchange units 6.

[0086] According to a non-limiting embodiment, the first and second retaining plates 13 are made of aluminium and have a thickness of 0.5 mm.

[0087] The heat storage and exchange device 5 further comprises a plurality of rods 14 (only one is shown) for holding the three heat storage and exchange assemblies 6 and the first and second retaining plates 13. According to this embodiment, each rod 14 passes freely through three heat storage and exchange assemblies 6 and is not welded to one of the flat heat exchangers 7. Each rod 14 can pass through a hole made in the middle of circular welds that join the flat heat exchanger plates 10 and embossed heat exchanger plates 11 of each flat heat exchanger 7.

[0088] Each rod 14 is inserted into a retaining orifice 15, for example of diameter 8 mm, passing through the first three heat storage and exchange assemblies 6 and the first and second retaining plates 13. A first end 16 of each of the rods 14 is welded to the first retaining plate 13 and a second end 17 of each of the rods 14 has a head 18 in contact with a spring element 19.

[0089] According to this non-limiting embodiment, the spring element 19 is disposed between the head 18 and the second retaining plate 13 via a cup 20.

[0090] The cup 20 comprises, on the one hand, a washer-shaped head 21 bearing on the second retaining plate 13 and, on the other hand, a body 22 inserted into the retaining orifice 15. In this non-limiting embodiment, the spring element 19 is formed by a compression spring and is disposed in the body 22 of the cup 20.

[0091] According to a non-limiting example of embodiment illustrated in [Fig.7] showing a heat storage and exchange device 5, the flat heat exchanger 7 is formed of a flat heat exchange plate 10 and an embossed heat exchange plate 11 placed one on top of the other and forming between them at least one conduit 12 for conveying a heat transfer fluid.

[0092] According to this non-limiting example, a filling product 23 having a thermal conductivity greater than 6W / m / K is disposed between the GNE 1 panel and the flat heat exchanger 7.

[0093] This filler product 23, which has high thermal conductivity, is used to flatten the irregular surface of the flat heat exchanger 7 by filling its hollows. The contact surface between the GNE 1 panel and the flat heat exchanger 7 is therefore maximized.

[0094] According to this non-limiting example, a filling product having a thermal conductivity greater than 6W / m / K is also disposed between the GNE 1 panel and the retaining plate 13.

[0095] In this case, the filler product 23 is used to fill any height differences that may be present when the GNE 1 panel is formed of a plurality of slats 4. This embodiment makes it possible to flatten the surface of the GNE 1 panel which is on the side opposite the flat heat exchanger 7.

[0096] The filling product 23 is for example formed by grinding and compacting a GNE 1 panel mixed with a contact grease, a thermal grease or a mixture of alloy or metal melting at a temperature higher than that at which the flat heat exchanger 7 is to operate.

[0097] According to another example of an embodiment of a heat storage and exchange device 5 illustrated in [Fig.8], the heat storage and exchange assembly 6 is equipped with a GNE panel 1 such as that illustrated in [Fig.1], a first flat heat exchanger 7 and a second flat heat exchanger 7.

[0098] One of the first and second planar heat exchangers 7 includes at least one conveying conduit 12 of a heat transfer fluid arranged to transmit heat from the conveying conduit to the panel GNE 1 and the other of the planar heat exchangers 7 includes at least one conveying conduit 12 of a heat transfer fluid arranged to absorb heat from the panel GNE 1.

[0099] The second planar heat exchanger 7 has a first heat exchange surface 8i in contact with a second heat exchange surface 82 of the first planar heat exchanger 7.

[0100] The heat storage and exchange device 5 further includes a retaining plate 13 in contact with a second main surface 92 of the GNE 1 panel.

[0101] In other words, the second planar heat exchanger 7 and the first retaining plate 13 are arranged on either side of the first planar heat exchanger 7 and the GNE 1 panel.

[0102] The heat storage and exchange device 5 further comprises a plurality of rods 14 (only one is shown) for holding the GNE panel 1, the first and second planar heat exchangers 7 and the retaining plate 13.

[0103] Each rod 14 is inserted into a retaining orifice 15 through the assembly 6 and the retaining plate 13. A first end 16 of each of the rods 14 is welded to the second flat heat exchanger 7 and a second end 17 of each of the rods 14 has a head 18 in contact with a spring element 19, said spring element 19 being disposed between the head 18 and the retaining plate 13.

[0104] According to a non-limiting example of embodiment illustrated in [Fig.9], the heat storage and exchange device 5 further comprises a heating element 24 disposed in contact with a GNE panel 1 and a flat heat exchanger 7.

[0105] For example, the heating element 24 can be formed by an electric heating film or a flat electric resistance. This electric heating is used to supply heat to the GNE 1 panel which stores the heat or to the planar heat exchanger 7 to provide a top-up of heat which is transferred to the heat transfer fluid circulating within the planar heat exchanger 7.

[0106] A thermal paste (not shown) can be used to improve heat transfer from the heating element 24. This thermal paste can be placed between the heating element 24 and the GNE panel 1, as well as between the heating element 24 and the flat heat exchanger 7. In the example shown, the heating element 24 is placed in a recess 25 in the GNE panel 1. In this case, the recess 25 can have a thickness equal to the thickness of the heating element 24.

[0107] In order to benefit from the natural convection of the heat transfer fluid in the planar heat exchanger 7, the latter can be placed vertically with the heat transfer fluid supply ducts 12 oriented vertically, and the heating element 24 placed in the lower part of the planar heat exchanger 7.

[0108] According to a non-limiting embodiment illustrated in [Fig. 10], at least one of the GNE 1 panels is arranged in a vacuum envelope 26. The envelope 26 is airtight and may be made of metal, for example aluminum, plastic, or a mixture of plastic and metal. The wall of the envelope 26 may have a thickness of 0.1 mm.

[0109] According to a different embodiment not illustrated, the envelope 26 can surround several GN 1 panels.

[0110] The envelopes 26 can be placed between two sheets, the perimeter of the envelopes being sealed to the two sheets by a flexible resin or rubber. This assembly can itself be placed under vacuum.

[0111] The stock can consist of GNE panels placed in vacuum envelopes, which are themselves placed between two sheets with a sealed perimeter, also forming a vacuum enclosure. This ensures better thermal contact between the outside of the sheets and the GNE panel.

[0112] Figure 11 illustrates a heat storage and exchange system 30 comprising a circuit 31 for conveying a heat transfer fluid. This circuit 31 is provided with four pipes 32 connected in parallel.

[0113] Each pipe 32 is equipped with a solenoid valve 33 arranged to allow or prohibit the circulation of a heat transfer fluid in the pipe 32.

[0114] According to this embodiment, three of the four pipes 32 comprise a heat storage and exchange device 5 according to the invention. The heat storage and exchange devices 5 are thermally insulated from each other.

[0115] In addition, the heat storage and exchange system 30 includes a temperature measurement device 34 of a heat transfer fluid circulating in the circuit 31.

[0116] The heat storage and exchange system 30 also includes control means 35 arranged to control the solenoid valves 33 according to a temperature of the heat transfer fluid measured by the temperature measuring device 34. [Fig. 12] illustrates an example of the implementation of a method 100 for controlling a heat storage and exchange system 30 such as that illustrated in [Fig. 11] allowing the heat transfer fluid to be cooled by a heat transfer from the heat transfer fluid to the heat storage and exchange devices 5.

[0117] According to a non-limiting embodiment, the process 100 includes a step of measuring 101, using the temperature measuring device 34, the temperature of the heat transfer fluid circulating in the circuit 31.

[0118] For cooling the heat transfer fluid circulating in the circuit 31, resulting in heat accumulation in the heat storage and exchange devices 5, when the temperature T is above 80°C, the process 100 performs the steps of • To control the opening, via the control means 35, of a first solenoid valve 33 in order to allow circulation of the heat transfer fluid in the pipe 32 associated with said first open solenoid valve 33 comprising a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of the heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0119] Then, when the temperature T is between 80°C and 60°C, the process 100 performs the steps of • To control 102 the opening, via the control means 35, of a second solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said open second solenoid valve 33 comprising a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0120] Then, when the temperature T is between 60°C and 30°C, the process 100 performs the steps of • To control 102 the opening, via the control means 35, of a third solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said open third solenoid valve 33 comprising a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0121] Finally, when the temperature T is below 30°C, process 100 performs the steps of • To control 102 the opening, via the control means 35, of a fourth solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said open fourth solenoid valve 33 which does not include a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0122] Figure 13 illustrates another example of the implementation of a method 100 for controlling a heat storage and exchange system 30 such as that illustrated in Figure 11, allowing the heat transfer fluid to be heated by a heat transfer from the heat storage and exchange devices 5 to the heat transfer fluid.

[0123] According to a non-limiting embodiment, the process 100 includes a step of measuring 101, using the temperature measuring device 34, the temperature of the heat transfer fluid circulating in the circuit 31.

[0124] To increase the temperature of the heat transfer fluid circulating in the circuit 31 via the heat storage and exchange devices 5 which transfer their heat to it, when the temperature T is below 40°C, the process 100 performs the steps of • To control 102 the opening, via the control means 35, of a first solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said first open solenoid valve 33 comprising a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0125] Then, when the temperature T is between 40°C and 60°C, the process 100 performs the steps of • To control 102 the opening, via the control means 35, of a second solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said open second solenoid valve 33 comprising a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0126] Then, when the temperature T is between 60°C and 80°C, the process 100 performs the steps of • To control 102 the opening, via the control means 35, of a third solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said third open solenoid valve 33, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0127] Finally, when the temperature T is above 80°C, process 100 performs the steps of • To control 102 the opening, via the control means 35, of a fourth solenoid valve 33 so as to allow circulation of the heat transfer fluid in the pipe 32 associated with said open fourth solenoid valve 33 which does not include a heat storage and exchange device 5, and • Control 103 the closure, via the control means 35, of the other solenoid valves 33 to prevent circulation of said heat transfer fluid in the pipes 32 associated with the closed solenoid valves 33.

[0128] Fig. 14 illustrates another example of the realization of a heat storage and exchange system 30 according to the invention.

[0129] This heat storage and exchange system 30 includes a circuit 31 for conveying a heat transfer fluid. This circuit 31 is provided with four pipes 32 connected in parallel.

[0130] Each pipe 32 is equipped with two solenoid valves 33 arranged at the inlet and outlet of the pipe 32, the two solenoid valves 33 forming a pair of solenoid valves 33. Each pair of solenoid valves 33 is arranged to allow or prohibit the circulation of a heat transfer fluid in the pipe 32 associated with this pair of solenoid valves 33.

[0131] According to this embodiment, three of the four pipes 32 comprise a heat storage and exchange device 5 according to the invention. The heat storage and exchange devices 5 are thermally insulated from each other.

[0132] In addition, the heat storage and exchange system 30 includes a temperature measurement device 34 of a heat transfer fluid circulating in the circuit 31.

[0133] The heat storage and exchange system 30 also includes control means 35 arranged to control the solenoid valves 33 according to a temperature of the heat transfer fluid measured by the temperature measuring device 34.

[0134] Figure 15 illustrates a method 200 for impregnating a GNE 1 panel. This method 200 comprises an impregnation step 201 of the GNE 1 panel during which the GNE 1 panel is placed vertically in a bath 40 of liquid phase-change material. The upper end of the GNE 1 panel emerges from the bath 40 during the impregnation step. The impregnation method 200 according to the invention therefore consists of positioning the GNE 1 panel vertically in the impregnation liquid while leaving one side or part of one side of the GNE 1 panel exposed to the air so as to facilitate air evacuation during impregnation.

Claims

Demands

1. Expanded and compressed graphite panel (1), said GNE panel, for thermal energy storage, said GNE panel (1) being impregnated with a phase change material, said GNE panel (1) being characterized in that it comprises a plurality of impregnation orifices (2) for the entry of said phase change material during liquid phase impregnation of said phase change material, each impregnation orifice (2) having a longitudinal axis (X) perpendicular to a compression plane (P) of said GNE panel (1).

2. GNE panel (1) according to the preceding claim, characterized in that it comprises a plurality of sealing elements (3), each impregnation orifice (2) being sealed by a sealing element (3).

3. GNE panel (1) according to any one of the preceding claims, characterized in that it is formed of several expanded and compressed graphite strips (4), said strips (4) being arranged side by side so as to form a parallelepiped panel, at least one of said strips (4) having a compression plane (P) perpendicular to at least one compression plane (P) of one of said other strips (4).

4. Heat storage and exchange device (5) comprising a heat storage and exchange assembly (6) provided with: • A first GNE panel (1) according to any one of the preceding claims; • A first flat heat exchanger (7) having a first heat exchange surface (8i) in contact with a first main surface (9J) of said GNE panel (1).

5. Device (5) according to the preceding claim, characterized in that it comprises: - A first retaining plate (13) in contact with a second principal surface (92) of the first GNE panel (1) parallel to the first principal surface (9i); - a plurality of rods (14), each rod (14) being inserted into a retaining orifice (15) passing through the heat storage and exchange assembly (6) and the first plate

6.

7.

8. of retaining (13), a first end (16) of each of said rods (14) being welded to the first flat heat exchanger (7) and a second end (17) of each of said rods (14) having a head (18) in contact with a spring element (19), said spring element (19) being disposed between said head (18) and said first retaining plate (13). Device (5) according to the preceding claim, characterized in that the first retaining plate (13) is formed by a second flat heat exchanger (7). Device (5) according to claim 4, characterized in that the heat storage and exchange assembly (6) further comprises a second GNE panel (1), the first flat heat exchanger (7) having a second heat exchange surface (82) in contact with a first main surface (9J) of said second GNE panel (1) parallel to the first main surface (9i) of the first GNE panel (1), said device (5) further comprising: - A first retaining plate (13) in contact with a second main surface (92) of the first GNE panel (1) parallel to the first main surface (9J) of the first GNE panel (1); - A second retaining plate (13) in contact with a second main surface (92) of the second GNE panel (1) parallel to the first main surface (9J) of the second GNE panel (1); - a plurality of rods (14), each rod (14) being inserted into a retaining orifice (15) passing through the heat storage and exchange assembly (6) and the first and second retaining plates (13), a first end (16) of each of said rods (14) being welded to said second metal plate (13) and a second end (17) of each of said rods (14) having a head (18) in contact with a spring element (19), said spring element (19) being disposed between said head (18) and said first retaining plate (13). Device (5) according to claim 4, characterized in that the heat storage and exchange assembly (6) comprises in addition to a second flat heat exchanger (7) having a first heat exchange surface (8i) in contact with a second heat exchange surface (82) of the first flat heat exchanger (7), said device (5) further comprising: - A first retaining plate (13) in contact with a second main surface (92) of the first GNE panel (1) parallel to the first main surface (9i) of the first GNE panel (1); - a plurality of rods (14), each rod (14) being inserted into a retaining orifice (15) passing through the heat storage and exchange assembly (6) and the first retaining plate (13), a first end (16) of each of said rods (14) being welded to the second flat heat exchanger (7) and a second end (17) of each of said rods (14) having a head (18) in contact with a spring element (19), said spring element (19) being disposed between said head (18) and said first retaining plate (13).

9. Device (5) according to any one of claims 5 to 8, characterized in that each retaining orifice (15) is provided in a slat (4) whose compression plane (P) is perpendicular to the longitudinal axis (X) of said retaining orifice (15).

10. Device (5) according to any one of claims 4 to 9, characterized in that each flat heat exchanger (7) is formed of a flat heat exchange plate (10) and an embossed heat exchange plate (11) placed one on top of the other and forming between them at least one conduit (12) for conveying a heat transfer fluid.

11. Device (5) according to the preceding claim, characterized in that a filling product (23) having a thermal conductivity greater than 6W / m / K is disposed between: - A GNE panel (1) and a flat heat exchanger (7); and / or - A GNE panel (1) and a retaining plate (13).

12. Device (5) according to the preceding claim, characterized in that the filler product (23) is formed by grinding and compacting a GNE panel (1) mixed with: - A contact grease; - A thermal grease; - An alloy mixture; or - A metal mixture.

13. Device (5) according to any one of claims 4 to 12, characterized in that it comprises a heating element (24) disposed in contact with a GNE panel (1) or with a GNE panel (1) and a flat heat exchanger (7).

14. Device (5) according to any one of claims 4 to 13, characterized in that at least one GNE panel (1) is arranged in a vacuum envelope.

15. Device (5) according to claim 14 characterized in that the stock comprises GNE panels placed in vacuum envelopes, which are themselves placed between two sheets with a sealed perimeter forming a vacuum enclosure.

16. Heat storage and exchange system (30) comprising: - A heat transfer fluid conveying circuit (31) having at least two parallel pipes (32), each pipe (32) being equipped with a solenoid valve (33) arranged to allow or prevent the circulation of a heat transfer fluid in said pipe (32), one of said at least two pipes (32) having a heat storage and exchange device (5) according to any one of the preceding claims; - A temperature measuring device (34) of a heat transfer fluid circulating in said circuit (31); - Control means (35), said control means (35) being arranged to control said solenoid valves (33) as a function of a temperature of said heat transfer fluid measured by said temperature measuring device (34).

17. A heat storage and exchange system (30) according to the preceding claim, characterized in that each pipe (32) is further provided with a second solenoid valve (33), one of said two solenoid valves (33) of a pipe (32) being disposed at the inlet of said pipe and the other of said two solenoid valves (33) of said pipe being disposed at the outlet of said pipeline (32), said two solenoid valves (33) of a pipeline being arranged to allow or prohibit the circulation of a heat transfer fluid in said pipeline (32).

18. A method (100) for controlling a heat storage and exchange system (30) according to claim 16 or 17, said method (100) being characterized in that it comprises the steps of: - Measure (101), using the temperature measuring device (34), the temperature of the heat transfer fluid; - Depending on the measured temperature of the heat transfer fluid, • To control (102) the opening, via the control means (35), of one or two solenoid valves (33) of a pipe (32) so as to allow circulation of the heat transfer fluid in the pipe (32) associated with said open solenoid valve(s) (33), and • To control (103) the closing, via the control means (35), of one or two solenoid valves (33) of another pipe (32) so as to prohibit a circulation of said heat transfer fluid in said other pipe (32) associated with said closed solenoid valve(s) (33).

19. Method (200) of impregnating a GNE panel (1) according to any one of claims 1 to 3, said method (200) comprising an impregnation step (201) of said GNE panel (1) in which said GNE panel (1) is placed vertically in a bath (40) of liquid phase-change material, one end of said GNE panel (1) emerging from said bath (40) during said impregnation step.

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