Device for storing thermal energy

Abstract

The present invention relates to a device (1) for storing thermal energy, the device comprising: a thermochemical storage means (2); a gas guide (2) connected to the thermochemical storage means (2) for supplying a gas to, and for removing the gas from, the thermochemical storage means (2); and a thermal-exchange-medium guide (4) connected to the thermochemical storage means (2) for supplying the thermal-exchange medium to, and for removing the thermal-exchange medium from, the thermochemical storage means (2); wherein the thermochemical storage means (2) comprises a thermochemical storage medium embedded in a matrix; wherein the matrix has a gas diffusion coefficient for the gas of 2.25*10-9 m2 / s to 4.25*10-9 m2 / s in a temperature range of -30°C to 300°C, and a maximum expansion ε in the Hooke's Law range of 25% to 300%; wherein the thermochemical storage medium is distributed substantially homogeneously in the matrix.

Description

[0001] Device for storing thermal energy

[0002] The invention relates to a device for storing thermal energy according to the preamble of claim 1.

[0003] Since many energy sources are inherently discontinuous, the ability to store energy is essential to keep energy available for specific applications and optimize its use. Short-term storage of only a few hours is typically appropriate, but some applications may require long-term storage of several months. Effectively balancing the temporal differences between the time of energy production and the time of demand, for example, during peak periods, remains a major challenge for the integration of renewable and sustainable energy sources into the existing energy supply chain. This applies to both electrical and thermal energy.

[0004] This problem is further exacerbated by the limited availability of some sustainable energy sources, where downtimes typically occur at night or during bad weather and often coincide with peaks in demand, further increasing the discrepancy between production and consumption.

[0005] The availability and development of efficient heat storage technologies is crucial for effectively matching energy supply to demand. Several heat storage strategies have been proposed and investigated for this purpose. One of the most important concepts is thermochemical heat storage, in which heat can be stored and released using a reversible chemical reaction. However, although thermochemical heat storage has the highest energy storage capacity compared to other energy storage technologies, it remains one of the least developed storage technologies to date.

[0006] Commercially available heat storage systems can be categorized into sensible and latent heat storage systems. Latent heat storage can be advantageous in some applications, as it avoids the main problems of sensible systems, such as corrosion of the working fluid or heat losses associated with the likely crystallization of melt in the system.

[0007] Traditionally, latent thermochemical storage devices are based on a ceramic matrix with a thermochemical storage medium embedded within it. When used in a device for storing thermal energy, this thermochemical storage medium enters an exothermic chemical reaction with a working fluid, thereby producing heat. Conversely, the supply of heat to the thermochemical storage medium leads to the release of the working fluid. Thus, the device can be integrated into a thermal system to store and maintain availability of process heat or even space heat, for example.

[0008] A challenge in the development of such devices for thermal energy storage is that the thermochemical storage medium undergoes volume expansion during the exothermic reaction with the working fluid. This expansion must be absorbed by the matrix in which the thermochemical storage medium is embedded. This volume expansion, or volume work, leads to mechanical stress on the matrix, which can cause it to become brittle or crack. In the case of conventional ceramic matrix materials, this typically leads to premature wear or failure of the device. Furthermore, it limits the maximum storage capacity.

[0009] The object of the present invention is to provide a device for storing thermal energy which avoids these disadvantages of the prior art.

[0010] This object is achieved by a device according to the invention for storing thermal energy having the features of claim 1.

[0011] The device according to the invention comprises a thermochemical storage unit, a gas duct connected to the thermochemical storage unit for supplying a gas to and removing the gas from the thermochemical storage unit, and a duct connected to the thermochemical storage unit for a heat transfer medium for supplying the heat transfer medium to and removing the heat transfer medium from the thermochemical storage unit. The thermochemical storage unit of the device according to the invention comprises a thermochemical storage medium embedded in a matrix. The matrix also has a gas diffusion coefficient for the gas of 2.25*10' 9 m 2 / s up to 4.25* 10' 9 m 2 / s in a temperature range of -30°C to 300°C, and a maximum expansion 8 in the Hookean range of 25% to 300%. This has the advantage that optimal gas exchange through the matrix with the thermochemical storage medium is achieved over a wide temperature range. This enables the use of the device according to the invention in a variety of applications, both in the private and industrial sectors. Due to the expansion in the Hookean range of 25% to 300%, the volumetric work of the thermochemical storage medium during the conversion of the gas in the thermochemical storage medium can be absorbed by the matrix without the matrix material experiencing irreversible deformation or being damaged. This allows the device to undergo many heat storage and heat release cycles without degenerating or losing performance.

[0012] Preferably, the matrix has a gas diffusion coefficient of 2.5* 10'9 m 2 / s up to 4*10' 9 m 2 / s, preferably 2.75*10' 9 m 2 / s up to 3.75*10' 9 m 2 / s, even more preferably from 3*10' 9 m 2 / s up to 3.5* 10' 9 m 2 / s, especially 3.25* 10' 9 m 2 / s, for the gas in a temperature range of -30°C to 300°C. This allows the matrix to be adapted to the specific application.

[0013] According to the preferred embodiment of the device according to the invention, the matrix comprises at least one polymer, which is preferably an elastomer. This achieves the advantage that the matrix can exhibit particularly high elongation in the reversible range. According to the preferred embodiment of the device according to the invention, the elastomer is a polysiloxane, preferably a polyalkylsiloxane, a polyurethane, 5-ethylidene-2-norbornene, perfluoroelastomer, tetrafluoroethylene / propylene, fluorosilicone rubber, fluorocarbon rubber, poly(butadiene-co-acrylonitrile), poly(butadiene-co-acrylonitrile-co-1,4-cyclohexanedimethanol diacrylate), poly(butadiene-co-acrylonitrile-co-acrylic acid), or poly(styrene-co-butadiene). These polymers have the above-mentioned properties, making them ideally suited for use in the device according to the invention.

[0014] The polyalkylsiloxane can also be selected from the group consisting of polydimethylsiloxane, poly(methylvinylsiloxane), poly(dimethylsiloxane-co-methylvinylsiloxane), trifluoropropylmethylsiloxane, and vinylmethylsiloxane. Polydimethylsiloxane (PDMS) is particularly preferred. To further increase the permeability of the polymer and further reduce the elastic modulus, the polymer base used can be mixed with a polymer curing agent in a ratio of 50:1 to 5:1, preferably 40:1 to 10:1, even more preferably 30:1 to 15:1, even more preferably 25:1 to 15:1, even more preferably 20:1.

[0015] The thermochemical storage medium in the context of the device according to the invention can be a salt, preferably a metal sulfate, even more preferably copper sulfate, cobalt sulfate, and zinc sulfate, with copper sulfate being most preferred because it is characterized by high peak temperatures, little to no material deterioration over the cycles, and high energy content. Metal sulfates offer the advantage of high cycle stability with low volatility. Copper sulfate, in particular, has proven itself as an energy storage medium (see, for example, Müller et al., Nanomaterials 2020, 10, 2485). Furthermore, if the device according to the invention is constructed with a transparent or at least semi-transparent material, the different coloration of copper sulfate (white / colorless) and copper ammonium sulfate (blue) can be used to determine whether the device according to the invention is "charged" or "discharged."The copper sulfate is preferably white in its initial state when dehydrated, or light blue in its hydrated state. After reaction with ammonia, it turns dark blue or violet, respectively. Thus, the intensity of the color can provide an indication of the charge level of the device according to the invention.

[0016] In order to achieve optimum storage capacity, the weight ratio between matrix and thermochemical storage medium is preferably 1:0.5 to 1:5, preferably 1:0.5 to 1:4, even more preferably 1:1 to 1:3, even more preferably 1:1 to 1:2. The weight ratio between matrix and thermochemical storage medium can influence heat release. It has been found that the rate of heat release is higher the more matrix there is in relation to the storage medium. The duration of heat release is also shorter. The heat release slows down the less matrix there is in relation to the storage medium. In return, the duration of heat release is longer. The heat release properties of the composition according to the invention can be controlled by the weight ratio between matrix and thermochemical storage medium.

[0017] According to the invention, the thermochemical storage medium is distributed substantially homogeneously within the matrix. According to an alternative embodiment not encompassed by the invention, the thermochemical storage medium can be enclosed within the matrix. A relatively homogeneous distribution of the storage medium within the matrix makes the storage medium even more accessible to the gas, thus accelerating the charging process.

[0018] The gas preferably comprises ammonia and / or water vapor. This allows the device according to the invention to use a gas that is readily available and inexpensive on the market.

[0019] In order to achieve a particularly compact design in the preferred embodiment and to improve the contact of the thermochemical storage device with the gas and the heat transport medium, the thermochemical storage device is preferably in flow connection with the gas guide on a first side and in thermal connection with the guide for the heat transport medium and / or the heat transport medium on a second side. The first side and the second side are also preferably arranged opposite one another. The thermochemical storage device can also be plate-shaped, wherein the device can preferably also comprise several plates of thermochemical storage. This optimizes the storage capacity of the device according to the invention.

[0020] The gas guide and the guide for the heat transfer medium preferably have transport directions oriented essentially orthogonally to one another. This improves heat transfer and reduces the required installation space for the device according to the invention.

[0021] According to the preferred embodiment of the device according to the invention, the device comprises a plurality of storage units, each of the storage units having three adjacent levels, with the gas guide arranged in a first level, at least one plate of thermochemical storage arranged in a second level, and the guide for the heat transfer medium arranged in a third level. This provides the device in the form of a microfluidic device. Furthermore, the storage units can be modularly interconnected, thereby achieving easy scalability of the device according to the invention.

[0022] In a further advantageous embodiment, the device can also be developed such that the device has at least one optical detection unit for detecting a color of the thermochemical storage device or the thermochemical storage medium, and a control device connected to the optical detection unit. As a result, gas saturation or the current utilization of the thermochemical storage device or the thermochemical storage medium can be determined based on the color of the thermochemical storage device or the thermochemical storage medium. The control device can further be designed to regulate an inflow of the gas and / or the heat transport medium to the thermochemical storage medium depending on the color of the thermochemical storage device or the thermochemical storage medium.In addition, the control device can be designed to regulate the outflow of the gas and / or the heat transfer medium from the thermochemical storage device or thermochemical storage medium depending on the color of the thermochemical storage device or the thermochemical storage medium. This allows the speed at which the thermochemical storage device should be filled or emptied to be regulated based on the detected color and thus the current utilization of the thermochemical storage device or the thermochemical storage medium. In particular, the device according to the invention can have at least one optical detection unit for detecting a color of the thermochemical storage device or the thermochemical storage medium for each of the thermochemical storage plates. This ensures precise and efficient control of the device according to the invention.

[0023] The heat transfer medium of the device according to the invention is preferably a thermal oil, wherein the thermal oil is preferably selected from the group consisting of mineral oils, silicone oils, polyglycols, fluorocarbons (HFCs), and chlorofluorocarbons. This ensures particularly efficient heat transfer. According to a further embodiment, the thermal oil is a polyglycol and is preferably selected from the group consisting of polyethylene glycol and polypropylene glycol.

[0024] According to one embodiment of the device according to the invention, the device can comprise connectors for connecting the device to one or more additional devices. This provides the advantage of being able to meet specific performance and capacity requirements.

[0025] Furthermore, the present invention relates to a system for storing thermal energy comprising at least two devices according to the invention, wherein the gas guides and the guides for the heat transport medium are each connected to one another in a serial or parallel configuration.

[0026] Advantageous embodiments of the devices according to the invention as well as alternative embodiments are explained in more detail below with reference to the figures.

[0027] Figure 1 shows a device according to the invention for storing thermal energy in a cross-sectional view.

[0028] Figure 2 shows a thermochemical storage device of the device according to the invention with a gas guide connected thereto in a view from above.

[0029] Figure 3 shows a guide for a heat transport medium of the device according to the invention for supplying a heat transport medium to and for removing the heat transport medium from the thermochemical storage device.

[0030] Figure 4 shows the device according to the invention with a gas guide and supply for the heat transport medium that are oriented essentially orthogonally to one another.

[0031] Figure 5 shows the device according to the invention with a gas guide and supply for the heat transfer medium oriented essentially parallel to each other. Figure 6 shows a further embodiment of the device according to the invention for storing thermal energy in a cross-sectional view.

[0032] Figure 7 shows a perspective view of one end of the device according to the invention according to Figure 6.

[0033] Figure 8 shows a system for storing thermal energy with several interconnected devices according to the invention according to Figure 6.

[0034] A device 1 according to the invention for storing thermal energy is shown in Figure 1 and Figure 6 in a schematic cross-sectional view. The device 1 according to the invention comprises a thermochemical storage device 2 and a gas guide 3 connected to the thermochemical storage device 2 for supplying a gas to and removing the gas from the thermochemical storage device 2. The thermochemical storage device 2 and the gas guide 3 are shown in detail in a schematic plan view in Figure 2. By supplying gas to the thermochemical storage device via the gas guide 3, an exothermic chemical reaction is initiated between the thermochemical storage device 2 or between a thermochemical storage medium contained in the thermochemical storage device 2 and not separately shown in the figures, and the supplied gas.The supplied gas is converted in the thermochemical storage 2 and at least partially absorbed, whereby energy is released in the form of heat.

[0035] Furthermore, the device 1 according to the invention comprises a guide 4 for a heat transport medium, which is connected to the thermochemical storage device 2 and is used to supply the heat transport medium to and remove the heat transport medium from the thermochemical storage device 2. The guide 4 for the heat transport medium can be seen in detail in Figure 3, which also shows a schematic plan view of the guide 4. The heat generated by the chemical reaction between the thermochemical storage medium and the supplied gas heats the heat transport medium, which is preferably transported continuously in the guide 4. This heat can subsequently be used, for example, as process heat, to generate electrical energy, and for other applications.

[0036] According to the invention, the thermochemical storage device 2 comprises the thermochemical storage medium embedded in a matrix, which is designed to react with the supplied gas. The matrix also has a gas diffusion coefficient for the gas of 2.25*10' 9 m 2 / s up to 4.25* 10' 9 m 2 / s in a temperature range from -30°C to 300°C, and a maximum expansion 8 in the Hooke' range of 25% to 300%. This has the advantage that optimal gas exchange through the matrix with the thermochemical storage medium is achieved over a wide temperature range. This enables the use of the device 1 according to the invention in a variety of applications, both in the private and industrial sectors. Due to the expansion in the Hooke' range of 25% to 300%, the volume work of the thermochemical storage medium during the conversion of the gas in the thermochemical storage medium can be absorbed by the matrix without the matrix material experiencing irreversible deformation or being damaged. As a result, the device 1 can undergo many heat storage and heat release cycles without degenerating or losing performance.

[0037] According to the preferred embodiment of the device 1 according to the invention, the matrix has a gas diffusion coefficient of 2.5*10' 9 m 2 / s up to 4*10' 9 m 2 / s, preferably 2.75*10' 9 m 2 / s up to 3.75*10' 9 m 2 / s, even more preferably from 3*10' 9 m 2 / s up to 3.5*10' 9 m 2 / s, especially 3.25* 10' 9 m 2 / s, for the gas in a temperature range of -30°C to 300°C. This allows the matrix to be adapted for use in different temperature ranges and for different gases. Furthermore, the matrix preferably comprises at least one polymer, even more preferably an elastomer. This has the advantage of increasing the reversible expansion range of the matrix. According to the preferred embodiment of the device 1 according to the invention, the elastomer is a polysiloxane, preferably a polyalkylsiloxane, a polyurethane, 5-ethylidene-2-norbornene, a perfluoroelastomer, tetrafluoroethylene / propylene, a fluorosilicone rubber, a fluorocarbon rubber, poly(butadiene-co-acrylonitrile), poly(butadiene-co-acrylonitrile-co-1,4-cyclohexane dimethanol diacrylate), poly(butadiene-co-acrylonitrile-co-acrylic acid) or poly(styrene-co-butadiene).These polymers have the above-mentioned properties, which makes them ideally suited for use in the device 1 according to the invention.

[0038] The polyalkylsiloxane can also be selected from the group consisting of polydimethylsiloxane, poly(methylvinylsiloxane), poly(dimethylsiloxane-co-methylvinylsiloxane), trifluoropropylmethylsiloxane, and vinylmethylsiloxane. Polydimethylsiloxane (PDMS) is particularly preferred. To further increase the permeability of the polymer and further reduce the elastic modulus, the polymer base used can be mixed with a polymer curing agent in a ratio of 50:1 to 5:1, preferably 40:1 to 10:1, even more preferably 30:1 to 15:1, even more preferably 25:1 to 15:1, even more preferably 20:1.The thermochemical storage medium in the context of the device 1 according to the invention can be a salt, preferably a metal sulfate, even more preferably copper sulfate, cobalt sulfate, and zinc sulfate, with copper sulfate being most preferred because it is characterized by high peak temperatures, little to no material deterioration over the cycles, and high energy content. Metal sulfates offer the advantage of high cycle stability with low volatility. Copper sulfate, in particular, has proven itself as an energy storage medium (see, for example, Müller et al., Nanomaterials 2020, 10, 2485). Furthermore, if the device 1 according to the invention is constructed with a transparent or at least semi-transparent material, the different coloration of copper sulfate (white / colorless) and copper ammonium sulfate (blue) can be used to determine whether the device according to the invention is "charged" or "discharged."As a result, the intensity of the coloration can provide an indication of the charge state of the device 1 according to the invention.

[0039] To achieve optimal storage capacity, the weight ratio between matrix and thermochemical storage medium is preferably 1:0.5 to 1:5, preferably 1:0.5 to 1:4, even more preferably 1:1 to 1:3, even more preferably 1:1 to 1:2. The weight ratio between matrix and thermochemical storage medium can influence heat release. It has been found that the rate of heat release is higher the more matrix there is in relation to thermochemical storage medium. The duration of heat release is also shorter. The heat release slows down the less matrix there is in relation to thermochemical storage medium. In return, the duration of heat release is longer. The heat release properties can be controlled by the weight ratio between matrix and thermochemical storage medium.

[0040] According to the invention, the thermochemical storage medium is distributed substantially homogeneously within the matrix. According to an embodiment not encompassed by the invention, the thermochemical storage medium can be enclosed within the matrix. A relatively homogeneous distribution of the storage medium within the matrix makes the storage medium even more accessible to the gas, thus accelerating the charging process.

[0041] The gas preferably comprises ammonia and / or water vapor. This allows the device according to the invention to use a gas that is readily available and inexpensive on the market.

[0042] According to the preferred embodiment of the device 1 according to the invention, a particularly compact design is achieved in that the thermochemical storage device 2 is preferably in flow connection with the gas guide 3 on a first side and in thermal connection with the guide 4 for the heat transfer medium and / or the heat transfer medium on a second side. This layered structure is visible in Figure 1. This also improves the contact of the thermochemical storage device 2 with the gas and the heat transfer medium. The first side and the second side are also preferably arranged opposite one another. This achieves the maximum contact area between the thermochemical storage device 2 and the gas or the heat transfer medium. The thermochemical storage device 2 can also be plate-shaped, whereby the device 1 can preferably also comprise several plates made of thermochemical storage device 2.This optimizes the storage capacity of the device 1 according to the invention. This can be seen in Figures 1 and 2, wherein the embodiment of the device 1 according to the invention shown in these figures comprises four plates of thermochemical storage 2.

[0043] According to an embodiment of the device 1 according to the invention shown in Figure 4, the gas guide 3 and the guide 4 for the heat transfer medium have transport directions oriented essentially orthogonally to one another. According to an alternative embodiment, the transport directions of the gas guide 3 and the guide 4 for the heat transfer medium are oriented parallel to one another or in opposite directions. This embodiment of the device 1 according to the invention is shown in Figure 5.

[0044] According to a preferred embodiment of the device 1 according to the invention (not separately shown in the figures), the device 1 comprises a plurality of storage units, each of the storage units having three adjacent levels, with the gas guide 3 arranged in a first level, at least one plate of thermochemical storage 2 arranged in a second level, and the guide 4 for the heat transfer medium arranged in a third level. Furthermore, the storage units can be designed to be modularly interconnected, thereby achieving simple scalability of the device 1 according to the invention.

[0045] The device 1 according to the invention can also be developed in a further advantageous embodiment such that the device 1 has at least one optical detection unit (not shown in the figures) for detecting a color of the thermochemical storage device 2 or the thermochemical storage medium, and a control device connected to the optical detection unit. The color of the thermochemical storage device 2 or the thermochemical storage medium can be used to determine a saturation with the gas or the current utilization of the thermochemical storage device 2 or the thermochemical storage medium. The optical detection unit can be designed, for example, as a CCD sensor. Alternative optical detection units are generally known to those skilled in the art. The control device preferably comprises a computer unit.The control device can further be configured to regulate an inflow of the gas and / or the heat transport medium to the thermochemical storage medium or the thermochemical storage 2 depending on the color of the thermochemical storage 2 or the thermochemical storage medium. Furthermore, the control device can be configured to regulate an outflow of the gas and / or the heat transport medium from the thermochemical storage 2 and / or the thermochemical storage medium depending on the color of the thermochemical storage 2 or the thermochemical storage medium. For this purpose, for example, one or more valves connected to the control device can be provided to regulate a flow of the gas or the heat transport medium.Based on the detected color and thus the current capacity of the thermochemical storage 2 or the thermochemical storage medium, it is possible to regulate how quickly the thermochemical storage 2 should be filled or emptied. In particular, the device 1 according to the invention can have at least one optical detection unit for detecting a color of the thermochemical storage 2 or the thermochemical storage medium for each of the plates of thermochemical storage 2. This ensures precise and efficient control of the device 1 according to the invention.

[0046] The heat transfer medium of the device according to the invention is preferably a thermal oil, wherein the thermal oil is preferably selected from the group consisting of mineral oils, silicone oils, polyglycols, fluorocarbons (HFCs), and chlorofluorocarbons. This ensures particularly efficient heat transfer. According to a further embodiment, the thermal oil is a polyglycol and is preferably selected from the group consisting of polyethylene glycol and polypropylene glycol.

[0047] The embodiment of the device 1 according to the invention shown in Figure 6, in addition to the components described with reference to Figure 1, additionally comprises a guide channel 8, which is designed to accommodate lines for the heat transfer medium and / or the gas (not visible in the figures). Alternatively, the guide channel 8 can also comprise two continuous, separate chambers within which the heat transfer medium and the gas are conducted. The use of the guide channel 8 is explained in more detail below with reference to Figure 8.

[0048] Figure 7 shows the embodiment variant of the device 1 according to the invention shown in Figure 6 in a perspective view. In this embodiment variant, the device 1 according to the invention comprises additional connectors 5, 6 for connecting the device 1 according to the invention to one or more further devices 1 according to the invention. Furthermore, the guide 4 for the heat transport medium and the gas guide 3 according to this embodiment variant each open into one or more connections which are suitable for being connected to the respective connections of a further device 1 according to the invention. According to the preferred embodiment variant of the device 1 according to the invention shown in Figure 7, the connectors 5, 6 are designed as plug-in connections, with one of the connectors 5, 6 being designed as a male connection and the other as a female connection.This makes it possible to connect multiple devices 1 in parallel and / or series, whereby their gas guide 3 and the guide 4 for the heat transfer medium are connected to each other. Alternatively, the connectors 5, 6 can also be designed as snap connections or similar.

[0049] Figure 8 shows an exemplary configuration of several devices 1 according to the invention, wherein the uppermost and the lowest of the illustrated devices 1 are arranged in a series circuit. Alternatively, two or more devices 1 can also be connected to one another in a parallel circuit. By connecting several devices 1 according to the invention, a system 7 for storing thermal energy is formed. A system 7 according to the invention for storing thermal energy comprises at least two devices 1 according to the invention, wherein the gas guides 3 and the guides 4 for the heat transport medium are each connected to one another in a serial or parallel configuration. By connecting several devices 1 according to the invention in a serial and / or parallel circuit, performance and capacity requirements for specific applications can be met.As shown in Figure 8, the guide channel 8 for the heat transfer medium and / or the gas makes it possible to connect the gas guide 3 and the guide 4 for the heat transfer medium of the uppermost device 1 with those of the lowermost device 1 in a space-saving manner, wherein additional devices 1 can be arranged between the uppermost and lowermost devices 1 in the system 7. This provides a space-saving and efficient routing for the heat transfer medium and the gas in the system 7, while simultaneously ensuring that a large number of devices 1 can be arranged in the smallest possible volume within the system 7.

Claims

Patent claims:

1. Device (1) for storing thermal energy comprising a thermochemical storage (2), a gas guide (3) connected to the thermochemical storage (2) for supplying a gas to and for discharging the gas from the thermochemical storage (2), and a guide (4) connected to the thermochemical storage (2) for a heat transport medium for supplying the heat transport medium to and for discharging the heat transport medium from the thermochemical storage (2), characterized in that the thermochemical storage (2) comprises a thermochemical storage medium embedded in a matrix, wherein the matrix has a gas diffusion coefficient for the gas of 2.25* 10' 9 m 2 / s up to 4.25* 10' 9 m 2 / s in a temperature range of -30°C to 300°C, and a maximum elongation 8 in the Hooke' range of 25% to 300%, wherein the thermochemical storage medium is substantially homogeneously distributed in the matrix.

2. Device (1) according to claim 1, characterized in that the matrix has a gas diffusion coefficient of 2.5*10' 9 m 2 / s up to 4*10' 9 m 2 / s, preferably 2.75*10' 9 m 2 / s up to 3.75*10' 9 m 2 / s, even more preferably from 3*10' 9 m 2 / s up to 3.5*10' 9 m 2 / s, especially 3.25* 10' 9 m 2 / s, for the gas in a temperature range of -30°C to 300°C.

3. Device (1) according to claim 1 or 2, characterized in that the matrix comprises at least one polymer.

4. Device (1) according to claim 3, characterized in that the at least one polymer is an elastomer.

5. Device (1) according to claim 4, characterized in that the elastomer is a polysiloxane, preferably a polyalkylsiloxane, a polyurethane, 5-ethylidene-2-norbornene, a perfluoroelastomer, tetrafluoroethylene / propylene, a fluorosilicone rubber, a fluorocarbon rubber, poly(butadiene-co-acrylonitrile), poly(butadiene-co-acrylonitrile-co-1,4-cyclohexane dimethanol diacrylate), poly(butadiene-co-acrylonitrile-co-acrylic acid) or poly(styrene-co-butadiene).

6. Device (1) according to claim 5, characterized in that the polyalkylsiloxane is selected from the group consisting of polydimethylsiloxane, poly(methylvinylsiloxane), poly(dimethylsiloxane-co-methylvinylsiloxane), trifluoropropylmethylsiloxane, and vinylmethylsiloxane.

7. Device (1) according to one of claims 1 to 6, characterized in that the thermochemical storage medium is a salt, preferably a metal sulfate, even more preferably copper sulfate.

8. Device (1) according to one of claims 1 to 7, characterized in that the weight ratio between matrix and thermochemical storage medium is 1 :0.5 to 1 :5, preferably 1 :0.5 to 1 :4, even more preferably 1 :1 to 1 :3, even more preferably 1 :1 to 1 :

2.

9. Device (1) according to one of claims 1 to 8, characterized in that the gas comprises ammonia and / or water vapor.

10. Device (1) according to one of claims 1 to 9, characterized in that the thermochemical storage (2) is in flow connection with the gas guide (3) on a first side, and is in thermal connection with the guide (4) for the heat transport medium and / or the heat transport medium on a second side.

11. Device (1) according to claim 10, characterized in that the first side and the second side are arranged opposite each other.

12. Device (1) according to one of claims 1 to 11, characterized in that the thermochemical storage (2) is plate-shaped, and the device (1) preferably comprises several plates of thermochemical storage (2).

13. Device (1) according to one of claims 1 to 12, characterized in that the gas guide (3) and the guide (4) for the heat transport medium have transport directions oriented substantially orthogonally to one another.

14. Device (1) according to claim 12, characterized in that the device (1) comprises a plurality of storage units, each of the storage units having three levels adjacent to one another in layers, and the gas guide (3) is arranged in a first level, at least one plate of thermochemical storage (2) in a second level, and the guide (4) for the heat transport medium is arranged in a third level.

15. Device (1) according to claim 14, characterized in that the storage units can be connected to one another in a modular manner.

16. Device (1) according to one of claims 1 to 15, characterized in that the device (1) has at least one optical detection unit for detecting a color of the thermochemical storage (2) or the thermochemical storage medium, and a control device connected to the optical detection unit.

17. Device (1) according to claim 16, characterized in that the control device is designed to regulate an inflow of the gas and / or the heat transport medium to the thermochemical storage medium depending on the color of the thermochemical storage (2) or thermochemical storage medium.

18. Device (1) according to one of claims 16 or 17, characterized in that the control device is designed to regulate an outflow of the gas and / or the heat transport medium from the thermochemical storage (2) or thermochemical storage medium depending on the color of the thermochemical storage (2) or the thermochemical storage medium.

19. Device (1) according to one of claims 1 to 18, characterized in that the heat transport medium is a thermal oil, preferably selected from the group consisting of mineral oils, silicone oils, polyglycols, hydrofluorocarbons (HFCs) and chlorofluorocarbons.

20. Device (1) according to one of claims 1 to 19, characterized in that the thermal oil is a polyglycol and is preferably selected from the group consisting of polyethylene glycol and polypropylene glycol.

21. Device (1) according to claims 12 and 16, characterized in that the device has for each of the plates of thermochemical storage (2) at least one optical detection unit for detecting a color of the thermochemical storage or the thermochemical storage medium.

22. Device (1) according to one of claims 1 to 21, characterized in that the device (1) comprises connectors (5, 6) for connecting the device (1) to one or more further devices (1).

23. System (7) for storing thermal energy comprising at least two devices (1) according to one of claims 1 to 22, characterized in that the gas guides (3) and the guides (4) for the heat transport medium are each connected to one another in a serial or parallel configuration.

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