A heat storage unit equipped with rails that serve as a heat storage element.

Abstract

This invention provides a heat storage device and method that enable particularly efficient heat storage with a simple design. [Solution] The heat storage body comprises a heat storage body (10) for storing thermal energy, a housing (2) in which the heat storage body (10) is housed, and at least one line (7) for a heat transfer fluid (6) for supplying thermal energy to and / or carrying away thermal energy from the heat storage body (10). Each of the heat storage bodies (10) comprises a longitudinal metal rail (11) with a cross section having a web (12) between widened ends.

Description

[[TECHNICAL FIELD]]

[0001] The present disclosure relates to a heat storage body and a method for operating a heat storage body. [[BACKGROUND ART]]

[0002] In the context of climate-friendly energy supply involving reduction of CO₂ emissions, heat storage systems are gaining increasing importance. For example, electrical energy generated by photovoltaic power plants or wind power plants during periods of sunny weather or strong wind can be converted into heat and stored as thermal energy in a heat storage body. The energy can be extracted at a later point in time for heating purposes or for generating electrical energy by a turbine generator unit, for example as described in European Patent No. 3379040 by the present applicant.

[0003] A general-purpose heat storage body includes a heat storage material for storing thermal energy, a housing that receives the heat storage material, and at least one conduit for a heat transfer fluid for guiding thermal energy toward the heat storage material and / or away from the heat storage material. Accordingly, in a general method for operating a heat storage body in which a heat storage material that stores thermal energy is received in a housing, thermal energy is guided by the heat transfer fluid toward the heat storage material and / or away from the heat storage material.

[0004] Generally, a heat storage body should, in particular, have the largest possible heat capacity, be able to be heated to the highest possible temperature for high energy conversion efficiency, and provide a large contact surface for rapid heat exchange. Furthermore, a high number of cycles should be possible during the heating and cooling phases without damaging or wearing down the heat storage body. A simple heat storage body, such as that described in German Patent Application Publication No. 102011007335, utilizes a concrete block as the heat storage body. However, to avoid damage, such heat storage bodies are ideally operated only at moderate temperatures and temperature changes. Moreover, the block shape provides only a small contact surface, resulting in relatively slow heat transfer. Heat storage bodies utilizing stone, granular materials, or similar porous materials provide a larger contact surface. However, high temperatures or numerous heating cycles can lead to failure, resulting in the collapse of granular materials, potentially making efficient heat transfer to, for example, a fluid gas impossible.

[0005] On the other hand, using a metal heat storage body, such as one made of steel, allows for higher temperatures and therefore higher energy conversion efficiency with greater long-term stability. Such a general-purpose heat storage body is described by the applicant in European Patent No. 3139107, which uses multiple steel plates as the metal heat storage body, stacked on top of each other with heat exchange pipes placed between them. However, when operating the heat storage body over a wide temperature range, thermal expansion can become a problem, especially if the heat exchange pipes, which have a different temperature than the steel plates, are in direct contact with the steel plates. Another approach, as published in International Publication No. 2019 / 025182, European Patent Application Publication No. 3633303, and European Patent Application Publication No. 3647677, describes metal rods specifically as heat storage bodies by the applicant. The metal rods can be arranged vertically or held horizontally via appropriate supports, spaced apart from each other. While most of the aforementioned general goals have already been achieved, there remains a desire to achieve the largest possible energy storage capacity and the possibility of rapid charging and discharging with a simple design. West German Patent No. 1005673 describes a heat exchanger in which multiple hairpin-shaped iron rods are suspended in a flow path as heat storage bodies. A heat dissipation medium and a heating medium are alternately passed through the flow path, and the multiple hairpin-shaped iron rods absorb and release heat, respectively. The hairpin shape allows the iron rods to be suspended, and consequently, facilitates the vibration of the iron rods for cleaning. [Overview of the project]

[0006] The objective of the present invention can be considered to be to provide a heat storage body and method that enable particularly efficient heat storage with a simple design.

[0007] This objective is achieved by a heat storage body having the features of claim 1 and by a method having the features of claim 12.

[0008] In the aforementioned type of heat storage body, according to the present invention, each heat storage body includes a metal rail having a longitudinal cross-sectional shape with a web between its wide ends.

[0009] Similarly, in the type of method described above, according to the present invention, each of the heat storage bodies includes a metal rail having a longitudinal cross-sectional shape with a web between its wide ends.

[0010] Because the web is thinner than the wide end, a relatively large contact surface is provided for heat exchange. This cross-sectional shape, also known as the I-beam shape, provides high mechanical stability. It also enables a stable scaffold, particularly stacking without the risk of collapse if, for example, the rails are incorrectly positioned. The wide end, i.e., one or both ends, provides a relatively high mass, and therefore a large heat capacity. A large heat storage capacity and high stability with a larger surface area than the heat storage bodies described in the introduction are achieved simultaneously by the present invention without requiring a complex or costly configuration.

[0011] Any embodiment Modifications of the heat storage body and the method according to the present invention are subject to the dependent claims and are described in the following description.

[0012] Rail shape One of the wide ends can form a base with a flat bottom in cross-section, if necessary. The base can be erected on the ground, and its flat bottom provides a reliable footing. By placing the base of one rail on the rail below, rails can be safely stacked.

[0013] Additionally or alternatively, one of the wider ends in the cross-section can form a rail head. The rail head can be rounded and can be directly joined to the web. The width of the rail head is greater than the width of the web and can also be called the central constriction region. If the other wider end forms the base, the width of the rail head can be made smaller than the width of the base as needed. A relatively large mass, and therefore a large heat storage capacity, is provided by the rail head. The mass of the rail head can be, for example, to constitute at least 30% or at least 40% of the total mass of the rail. This means that in the cross-section of the rail (perpendicular to the longitudinal axis of the rail), the cross-sectional area of ​​the rail head is at least 30% or at least 40% of the cross-sectional area of ​​the rail. The optional rounding or curvature of the rail head relates to the side of the rail head opposite the web and prevents the contact surface with the flat bottom of adjacent rails from becoming excessively large when rails are stacked on top of each other. The overall arrangement of multiple rails with curved rail heads results in a larger surface area, and therefore faster heat exchange to the heat transfer fluid.

[0014] Railway rails / railway track rails, such as those manufactured for trains or other railway vehicles, are a good example of rails. Railway rails combine the aforementioned advantages and are typically made of suitable steel or steel alloys, allowing for heat storage operation at high temperatures, for example, above 600°C, without rapid material fatigue.

[0015] Rail arrangement At least some of the rails can be positioned adjacent to one another, and rigid mechanical connections between the rails are not required. Therefore, when a temperature gradient occurs within the heat storage body, the rails can thermally expand and contract relative to each other, so that the thermal expansion of the rails does not lead to fracture or excessive stress.

[0016] In particular, rails within a housing can be stacked on top of each other in multiple levels or layers. Rails in one layer can be placed directly on top of rails in the layer below. Rails belonging to the same layer can be placed essentially parallel to each other. This includes rails placed exactly parallel to each other, or rails placed so that the angle between their longitudinal axes is up to 10° or up to 15°. Rails in directly adjacent layers can be placed so that one rail rests on multiple rails below it, intersects them, and especially orthogonally. This ensures a reliable scaffolding without the risk of upper rails accidentally falling between lower rails.

[0017] All rails can be erected on their respective bases. Thus, the bases of the lowest layer of rails are erected on the substrate, while the bases of the remaining layers rest on the rails below them. Alternatively, some rails can be rotated and positioned so that their bases face sideways or upwards and their rail heads potentially face downwards. In particular, adjacent rails can be erected alternately on their bases or rail heads, i.e., rails within the same layer are alternately oriented so that their bases or heads face downwards. This allows for the acceptance of additional rails in the free space between two rails erected on their respective bases, thereby providing a higher heat storage capacity in the same space, while simultaneously keeping the rail surfaces accessible to the heat transfer fluid.

[0018] In the modified configuration described, the rails are stacked on top of each other, but this can be modified so that the rails do not directly touch each other, but rather are spaced apart, for example, by using (metal) separating plates or perforated plates.

[0019] In principle, the rails can also be arranged upright, so that their longitudinal axes are perpendicular, and the described cross-sections form the base surfaces of each rail. The advantages mentioned above are also achieved in this embodiment, but in particular, the described shape provides sufficient contact surface area for rapid heat exchange and high mechanical stability. By arranging the rails in direct contact with each other, a large heat storage capacity and a large surface area for heat exchange can be provided in a limited space. Compared to, for example, a longitudinal heat storage body with a circular or square cross-section, the shape according to the present invention provides a larger surface area for the same cross-sectional area / heat storage capacity. Furthermore, when adjacent rails are in direct contact, access to a large portion of the rail surface for the heat transfer fluid is maintained, in contrast to, for example, a bar with a square cross-section where a large portion of the surface area is inaccessible to the heat transfer fluid due to flush contact.

[0020] Heat transfer fluids and heat sources In principle, the heat transfer fluid can be any gas or gas mixture, vapor, or any liquid, such as water or hot oil. The gas mixture can be ambient air or a shielding gas, and its moisture and / or oxygen content is reduced, for example, to prevent corrosion. In variations of the present invention, the heat transfer fluid is used to heat the heat storage body and (at another time) to extract heat from the heat storage body. In other variations of the present invention, the heat transfer fluid is used either to heat the heat storage body only or to extract heat from the heat storage body only. In these variations, a second heat transfer fluid is introduced independently from the aforementioned heat transfer fluid, with one heat transfer fluid used only to supply heat and the other heat transfer fluid used only to remove heat. The two heat transfer fluids can be the same fluid or different fluids. Heat supply can also be performed by a heating element in the housing, as will be described in more detail later, in which case one heat transfer fluid for heat extraction is sufficient.

[0021] The heat transfer fluid can be received in the empty space formed between the base, head, and web of adjacent rails. Because it flows directly along the rails, it can be brought into direct contact with the rails.

[0022] When two independently guided heat transfer fluids are used to transfer heat to and from a heat storage body, one heat transfer fluid can be guided through a pipe conduit between the rails, while the other heat transfer fluid can be guided through another pipe conduit between the rails or freely along the rails (i.e., in direct contact with the rails). The pipe conduits can be pressed against or welded to the rails to provide better thermal contact.

[0023] The conduit for the heat transfer fluid mentioned at the beginning can be a conduit guided into a housing, and the heat transfer fluid flows freely within the housing. Alternatively, the conduit can include pipes inside the housing, and the heat transfer fluid flows only through the pipes and not through the remaining free space within the housing. The conduit can be understood as a conduit system, which may also include connections to multiple pipes running adjacent to each other. The conduit can also form a circuit through which the heat transfer fluid circulates, for example, by one or more pumps. The circuit can run entirely inside the housing, or partially inside and outside the housing. A heat exchanger, which can be located outside the housing in particular, can be coupled to the conduit to transfer heat to and / or extract heat from the heat transfer fluid. This heat exchanger can provide heat exchange to another fluid or fluid circuit, for example. In particular, waste heat from another system, such as waste heat from a steel mill or power plant, heat from exhaust gases from a combustion process, or heat released by an exothermic chemical reaction can be introduced through the heat exchanger.

[0024] The heat storage body may optionally be provided with an electric heating element, whereby electrical energy is converted into heat energy, which is then transferred to the heat storage body and stored there. The heating element may be arranged in the circuit of the heat transfer fluid such that heat from the heating element is transferred to the rails via the heat transfer fluid. Alternatively, the electric heating element may be arranged between adjacent rails. A suitable free space for the heating element is formed in the cross-section between the rails by the web and two thick ends of the rail and by the periphery of at least one adjacent rail. The heating element can in principle be of any design, for example one that generates heat as a result of electrical resistance.

[0025] General characteristics The housing can basically be understood as a wall of any shape surrounding the heat storage body. The housing may be provided with a heat insulating material to reduce heat loss from the heat storage body to the environment outside the housing. In some embodiments, the housing forms a boundary for the heat transfer fluid. If the heat transfer fluid is in gaseous or vaporous form, the housing can be made airtight except for a fluid port. The fluid port can be connected to a conduit for the heat transfer fluid for conveying the heat transfer fluid through the housing. In principle, the housing can also be filled with a heat transfer fluid in liquid form, wherein the rails are submerged in the liquid. In other embodiments, the wall of the housing is not in direct contact with the heat transfer fluid, and instead the conduit for the heat transfer fluid comprises a plurality of pipes penetrating the housing along the rails.

[0026] The elongated shape of the rail can be understood to mean that the dimension of the rail in the longitudinal direction is at least 5 times or at least 10 times larger than the width and / or height of the rail, wherein the width and height should be understood to be orthogonal to the longitudinal direction. The cross-section is orthogonal to the longitudinal direction. The cross-sectional shape of the rail can be constant along the entire longitudinal direction. In principle, the rail can also be curved along the longitudinal direction.

[0027] Further, when the features of the present invention described as additional device features are incorporated as intended, a modified example of the method according to the present invention is provided. Conversely, the heat storage body can also be configured to implement the described modified example of the method. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Further advantages and features of the present invention are described below with reference to the attached schematic drawings. [Figure 1] Figure 1 is a schematic diagram of an example embodiment of the heat storage body according to the present invention. [Figure 2] Figure 2 shows a cross-section of a rail in an example embodiment of the heat storage body according to the present invention. [Figure 3] Figure 3 is a schematic diagram of a further example embodiment of the heat storage body according to the present invention. [Figure 4] Figure 4 is a schematic cross-sectional view of a rail arrangement in an example embodiment of the heat storage body according to the present invention. MODE FOR CARRYING OUT THE INVENTION

[0029] Various example embodiments are described below with reference to the drawings. As a general principle, similar elements and elements that function in a similar manner are denoted by the same reference signs.

[0030] Examples of embodiments shown in Figures 1 and 2. An example embodiment of the heat storage body according to the present invention is described below with reference to Figure 1 and Figure 2, which schematically show a heat storage body 1 having a plurality of rails 11 as a heat storage member 10. Figure 2 shows a cross-section of one of the rails 11.

[0031] The heat storage body 1 comprises a housing 2 that receives a plurality of rails 11 as a heat storage body 10. A conduit 7 for the heat transfer fluid 6 is guided into the housing 2. In the illustrated example, the conduit 7 is guided into the housing 2 so that the heat transfer fluid 6 can flow freely through the housing 2 along the rails 11. A circuit 7A having the conduit 7 for the heat transfer fluid 6 is formed, and the heat transfer fluid 6 can be circulated along the heat storage body 10 by, for example, a pump (not shown here).

[0032] The conduit 7 is thermally connected to the heat exchanger 3 to transfer thermal energy between the heat transfer fluid 6 in the conduit 7 and another fluid in the independent conduit 4. The heat exchanger 3 can be used, in particular, to extract heat from the heat storage body 1 so that the fluid in the conduit 4 can be heated and used, for example, for supply to a building or a hot water heating system. Due to its configuration as a high-temperature heat storage body, the heated fluid in the conduit 4 is also suitable for generating electrical energy. The introduction of thermal energy can also occur in a heat exchanger thermally connected to the conduit 7, similar to the illustrated heat exchanger 3. However, in the illustrated example, instead, an electric heating element 20 is provided that uses electrical energy to heat the heat transfer fluid 6.

[0033] Unlike conventional heat storage bodies, in the illustrated example, multiple rails 11, which are railway tracks, are used as the heat storage body 10. The rails 11 are stacked on top of each other in layers 12A to 12D. Multiple rails 11 can be arranged substantially parallel to each other so as to form each horizontally extending layer 12A, layer 12B, layer 12C, or layer 12D. Rails 11 in directly adjacent layers, for example layers 12A and 12B, are arranged to intersect each other relative to each other. In the illustrated example, rails 11 in different layers are arranged perpendicular to each other, but other angles are also possible. Thus, rail 11 rests on multiple rails 11 below it, for example, at least 5 or at least 10 rails 11. Empty spaces 19 are formed between the rails 11 through which the heat transfer fluid 6 flows. In this way, the empty spaces 19 form channels along the longitudinal direction of the rails 11.

[0034] As shown in Figure 2, the rail 11 may have a uniform cross-section along its length. In the cross-section, the rail 11 consists of two wide ends 13 and 14 joined to each other by a relatively narrow web 12. The aforementioned cross-section can be manufactured as a single piece or from at least the same material. The wide end 14 constitutes the base 16, and the wide end 13 forms the rail head 15. The base 16 has a flat bottom that contributes to a reliable base. The width of the base 16 or its bottom is also greater than the width of the web 12 and greater than the width of the rail head 15. The width should be understood as being in the direction perpendicular to the longitudinal axis of the rail 11 and the direction perpendicular to the direction in which the rail head 15 and the base 16 are joined. Therefore, the surface area of ​​the bottom of the base 16 is defined by the width and length of the base.

[0035] The rail head 15 has a relatively large mass and therefore allows for the storage of a large amount of thermal energy. At the same time, the surface area of ​​the rail 11, and therefore the heat exchange area, is considerably larger than, for example, that of a rectangular rod of the same length and cross-sectional area. The smaller the width of the rail head 15 is compared to the width of the base 16, the more accessible the bottoms of any further rails placed on the rail head 15 remain. This allows for better thermal energy exchange than in the case of a symmetrical double T-beam cross section having the same shape as the base instead of the rail head. Furthermore, rounding at least the top of the rail head 15 reduces the contact surface area with adjacent rails, further increasing the surface area over which the rail 11 can exchange thermal energy with the heat transfer fluid.

[0036] Figure 1 shows an arrangement of rails 11 in which all rails 11 extend in a horizontal plane and the rails 11 are stacked on top of each other; however, many of the effects and advantages described can also be achieved in a modified arrangement in which the rails 11 are erected upright so that their longitudinal axes extend vertically. The vertically arranged rails 11 can be erected on perforated plates as needed to facilitate the continuous flow of heat transfer fluid along their longitudinal axes. Another possible arrangement of rails 11 is described below with reference to Figure 3.

[0037] Figure 3: Example of an embodiment Figure 3 schematically shows another modified embodiment of the heat storage body 1 according to the present invention. This modification differs from the embodiment described above in the arrangement of the rails 11. These are also railway rails with their longitudinal axes oriented horizontally. However, within the layers (i.e., at the same height), the bases 16 and rail heads 13 alternately face downwards. Thus, the rails 11 erected on the heads are positioned between two rails 11 erected on the bases 16. This reduces, in principle, the volume between the rails 11 that can utilize the heat transfer fluid. At the same time, the accessible surfaces of the rails 11 remain essentially the same as in the example shown in Figure 1 (having the same number or mass of rails). Depending on the heat transfer fluid used and the desired flow characteristics, the designs shown in Figure 1 or Figure 3 may be more preferable.

[0038] Figure 3 also shows that when the rails 11 are stacked, each layer or layer 12A-12F does not need to be oriented to intersect or perpendicular to the adjacent layer. Instead, the longitudinal axes of two rails 11 placed vertically are essentially parallel, for example, in layer 12A and layer 12B. The next rail 11 placed above it (in layer 12C) runs perpendicular to the two rails 11 below it. Figure 3 further shows, as an example, that optional fasteners, such as metal chains, can be used to hold portions of the rails in place or to facilitate the transport of the rails during the assembly of the heat storage unit.

[0039] Figure 4: Embodiment Example Figure 4 shows an alternative arrangement of rails 11 that can be used in the embodiment example of Figure 1 or Figure 2. The heat transfer fluid is again received in the free space or empty space 19 formed between adjacent rails 11. In addition, a pipe conduit 8 through which further heat transfer fluid 5 passes is guided to penetrate at least a portion of the empty space 19. One of the two heat transfer fluids 5,6 can be used to introduce heat into the heat storage, and the other of the two heat transfer fluids 5,6 plays a role in extracting heat from the heat storage.

[0040] The examples of embodiments described are purely illustrative, and modifications of these embodiments are possible within the scope of the appended claims. For example, the design of the conduit 7 for the heat transfer fluid can be modified so that the conduit 7 also extends through the housing 2, or extends exclusively within the housing 2, and / or so that only the supply and removal of the heat transfer fluid 6 to and from the rails 11 occurs, instead of the closed circuit 7A formed by the conduit 7. In general, the description of an element should be understood to mean "at least one" such element. For example, it is also possible to provide multiple conduits 7 to guide the heat transfer fluid to different rails 11 within the housing 2, partially or completely independently. This allows the rails 11 to be heated to different temperatures and allows for a choice of which rail to extract heat from, potentially increasing the energy conversion efficiency of the thermal energy use. The drawings should also be understood as schematic principles and can be supplemented with additional components, such as pumps, fans, flow baffles, insulation, pressure relief conduits, temperature and pressure sensors, or additional heat storage devices, in addition to the rails shown. [Explanation of Symbols]

[0041] 1…Heat storage 2… Housing 3...Heat exchanger 4…Independent conduit / independent fluid circuit 5… Heat transfer fluid 6… Heat transfer fluid 7…Conduit for heat transfer fluid 7A... Circuit for heat transfer fluid 8… Pipe conduits for heat transfer fluids 10… Heat storage element 11... Rails 12A~12F... Layer 11 of rails 12…Web 13, 14… Wide end 15... Railhead 16...Base 19... Empty space between rails 11 20… Electric heating element

Claims

1. A heat storage body, Multiple heat storage bodies (10) for storing thermal energy, A housing (2) that receives the heat storage body (10), and The system comprises at least one conduit (7) for a heat transfer fluid to guide thermal energy toward and / or away from the heat storage body (10), A heat storage body characterized in that each of the heat storage elements (10) includes a metal rail (11) having a longitudinal cross-sectional shape with a web (12) between its wide ends (13, 14).

2. The heat storage body according to claim 1, wherein one of the wide ends (14) forms a base (16) having a flat bottom in cross-section.

3. The heat storage body according to claim 2, wherein one of the wide end portions (13) is directly joined to the web (12) in cross-section and forms a rail head (15) having a width greater than the width of the web (12) and less than the width of the base portion (16).

4. The heat storage body according to claim 3, wherein the mass of the rail head (15) is at least 40% of the total mass of the rail (11).

5. The heat storage body according to any one of claims 1 to 4, wherein the rail (11) is formed by a railway rail.

6. A heat storage body according to any one of claims 1 to 5, wherein a plurality of rails (11) are stacked on top of each other in a plurality of layers (12A to 12F) in the housing (2).

7. The heat storage body according to claim 6, wherein the rails (11) of the same layer (12B) are arranged parallel to each other, and the rails (11) of adjacent layers (12A, 12C) are arranged to intersect them.

8. A heat storage body according to any one of claims 3 to 7, wherein all rails (11) are erected on their respective bases (16), or adjacent rails (11) are alternately erected on their bases (16) or their rail heads (15).

9. The heat storage body according to any one of claims 3 to 8, wherein the heat transfer fluid (6) is received in a space (19) formed between the base (16), rail head (15), and web (12) of adjacent rails (11).

10. Two independently guided heat transfer fluids (5, 6) are provided for guiding heat toward the heat storage body (10) and for guiding heat away from the heat storage body (10). One of the heat transfer fluids (5) is led to a pipe conduit (8) between the rails (11), and The other heat transfer fluid (6) is guided freely along the rails (11) or into other pipe conduits between the rails (11), as described in any one of claims 1 to 9.

11. A heat storage body according to any one of claims 1 to 10, wherein an electric heating element (20) is arranged between adjacent rails (11) or within a circuit (7A) of a heat transfer fluid (6).

12. A method for manipulating a heat storage body, Multiple heat storage bodies (10) that store thermal energy are received in the housing (2), Using the heat transfer fluid (6), thermal energy is guided toward and / or away from the heat storage body (10). A method characterized in that each of the heat storage bodies (10) includes a metal rail (11) having a longitudinal cross-sectional shape with a web (12) between wide ends (13, 14).

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