WO2024014968A1

WO2024014968A1 - Thermal energy storage and method for storing thermal energy

Info

Publication number: WO2024014968A1
Application number: PCT/PL2023/000036
Authority: WO
Inventors: Bogdan Wera
Original assignee: TERRAEN-MAGAZYNY ENERGII Sp. z o.o.
Priority date: 2022-07-12
Filing date: 2023-07-11
Publication date: 2024-01-18
Also published as: PL441712A1

Abstract

A thermal energy storage includes a filling (5) accumulating thermal energy in a space separated with side walls (2), the base (3) and the lid (4). Inside the filling (5), it includes at least one heating pipeline (7) of the filling (5) routed in layers, connected via a supplying pipeline (11) with a solar collector (6), through a manifold (12) and a solenoid valve (10) and with a pipeline and a controller (16) controlling the recirculation pump (15) of the closed heating medium circuit. The side wall (2) includes an active insulation system, which contains at least one outer heating pipeline (9) supplied with a heating medium from the solar collector (6) around the outer passive insulation layer (13.2). The active insulation system also includes a heating pipeline (8) inside the reinforced concrete layer (14), supplied with the heating medium. The method for storing thermal energy is characterised in that the filling is heated by the heating pipeline (7) using the heating medium drawn by the recirculation pump (15) from the solar collector (6) and which is returned in a closed circuit to the solar collector (6). The outer heating pipeline is used to heat the outer surface of the side walls (2) and soil layers adjacent to the storage (1). Heating medium with temperature lower than the filling (5) temperature inside the storage (1) is fed to the aforementioned heating pipeline (9).

Description

Thermal energy storage and method for storing thermal energy.

The subject of the invention is a thermal energy storage and a method for storing thermal energy in underground containers. Such storage spaces enable underground collection and storage of thermal energy received from devices collecting energy mainly from renewable thermal energy sources, in particular from thermal solar collectors. The energy stored in the storage space is intended for later use by drawing heat from a dedicated exchanger and heat transfer for utility purposes. The heat storage can use soil, gravel or cork as a heat accumulating filler.

A range of solutions disclosing the design of a thermal energy storage are known.

The patent document RU2618633C2 discloses a metal device for thermal energy accumulation from an external source, provided with double insulation. The metal device according to the invention accumulates solar energy at a high temperature from 100 to 1300 degrees. A heat exchanger is located near the metal medium accumulating thermal energy. In order to insulate the device walls, a double insulation of the concrete core is provided for according to the invention, as internal and external insulation of the concrete core. The insulation includes insulating wall layers, floor layers and lid layers, wherein it also has a layer provided as a mirror reflecting infrared radiation.

The document CN107076524 discloses an- heat storage system and a heat storage unit, which includes a material strongly correlating the electron system and a part used to exchange heat, which includes material with higher thermal conductivity than the first material, wherein the aforementioned heat exchanging part is in contact with the heat storage part. According to the invention, ceramics or metal materials can be used as the material with higher thermal conductivity. The heat storage unit may have a multiple layer structure, in which the heat storage and heat exchange parts are laminated alternately. The patent document JP2000154985 discloses a solution related to an underground heat storage container. The container is formed by surrounding a part of the soil with an underground wall, wherein water storing the heat is located inside the container. A range of wells reaching the aquifer are located inside the underground heat storage container, wherein temperature distribution sensors recording the distribution of temperature of water storing the heat are located at various locations across the aquifer. On the basis of the temperature distribution detected by the sensors, some of the wells are selected and water storing heat is drawn from them, whereas storage water containing smaller quantities of stored heat is released from the remaining wells to the aquifer. Each of the wells is adequately provided with an outlet-inlet valve and is used for both water discharge and collection. The heat storing water is purified at water treatment devices before it returns to the aquifer.

Thermal energy storage method solutions intended for underground use in such devices are also known.

The patent document DE102007056943A1 discloses a heat accumulation method from the ground, which involves heating air used as the thermal energy medium. The air is pre-heated in a solar collector and transferred through one or multiple drilled openings deep into the ground. Air circulation is forced in order to achieve heat storage.

The patent document JPS60174457A discloses a method of underground thermal energy storage in storage spaces with high thermal capacity. A container with a separating film, filled with sand, gravel and water is placed underground and then covered with soil around its circumference and on its top, such that water flow is enabled. The container with the film is installed under a garden roof and sand and gravel are loaded inside the foil and enable water flow. The hot water inlet pipe is open towards the bottom part of the container, and the pipe through which hot water flows, is placed in the top part, inside the container. After two-three months from the time hot water is transferred inside the film in order to achieve the desired heat accumulation, ground temperature inside the container increases while the ground temperature around the container is maintained at a constant level.

The objective of the invention is to develop a thermal energy storage and a method for storing thermal energy. The underground thermal energy storage space is intended to extend the useful time, during which the user may use the accumulated heat. The objective is to use the heat generated by a solar collector during the time, when heating medium harvested from the collectors has parameters inadequate to heat the filling. This applies to the temperature of water or another heating medium, such as glycol, air, etc. present inside the solar collector. The general term of heating medium is used throughout the disclosure, which includes all types of heat mediums enabling heat collection from a solar collection and subsequent release of said heat inside the thermal energy storage and its future use. Thus, the objective of the invention is to use thermal energy with parameters useless for further heating of the storage space filling. In the known solutions, this part of thermal energy, for example with parameters below the temperature inside the thermal energy storage space, was not used.

In the known solutions, the thermal energy storage space includes a fragment of soil separated from the surrounding soil bulk. This fragment of soil is usually separated at the bottom with a passive layer provided as a layer of closed-cell polyurethane insulation. Around the sides and at the top, the storage space is separated from the remaining soil by, looking from the inside of the storage space: inner passive layer provided as closed-cell polyurethane, followed by an intermediate carrier layer and an outer passive layer of closed-cell polyurethane. In the known solutions, a heating tube unit is routed inside the filling of the heat storage. The soil filling may be supplemented or replaced with rock, gravel filling or other types of fillings accumulating heat. This storage filling is heated by the heating medium. Pipes containing the heating medium are usually supplied from the solar collector by a pump, a hydraulic manifold provided with solenoid valves and a control unit cutting off the heating medium supply to heating pipelines in the filling, if the temperature of this heating medium from the solar collector drops below the filling temperature inside the storage space.

The objective of the invention is to develop a novel thermal energy storage solution provided with passive insulation in the form of closed-cell polyurethane panels and active insulation with heating pipes, using heat generated by the solar collector. Another objective of the invention is to develop a novel method of storing thermal energy. The task of the solution is to use the heating medium during periods, in which the parameters of said heating medium, temperature in particular, are inadequate for the purpose of increasing the quantity of stored heat, for example, when heating medium temperature is lower than the filling temperature inside the storage space.

According to the invention, the thermal energy storage contains a filling accumulating thermal energy inside the space separated with side walls, the base and the lid, while inside the filling, it includes at least one heating pipeline of the filling placed as a layer. The side walls of the storage space have a layered design, with a carrier layer of reinforced concrete placed between the layers of inner passive insulation and other power insulation. The heating pipeline of the filling is connected with the solar collector via at least one supplying pipeline, through a manifold and at least one thermostatic solenoid valve. The storage space includes a return pipeline and a controller controlling the recirculation pump of the heating medium circuit.

The thermal energy storage according to the invention is characterised in that the side wall with a layer design includes an active insulation system which includes at least one heating pipe system supplied with the heating medium from the solar connector via the supply pipeline, through at least one solenoid valve and a manifold.

The active insulation system preferably includes, around the outer passive insulation layer, around the side walls of the energy storage, at least one outer heating pipeline connected with the solar collector via at least one supplying pipeline, a manifold and at least one thermostatic solenoid valve.

In another preferable embodiment, the active insulation system includes at least one heating pipeline in a reinforced concrete layer inside the side walls, connected with the solar collector via at least one supplying pipeline, a manifold and at least one thermostatic solenoid valve.

The lid of the storage space may include at least one heating pipeline routed through the reinforced concrete layer.

The heating pipe systems in the heating pipeline of the reinforced concrete layer and in the outer heating pipeline are preferably parallel in each of those pipelines.

The heating pipelines may include any, at least one pipeline system independently supplied with the heating medium.

The method for storing thermal energy involves heating the filling of the thermal energy storage using the heating pipeline and heating medium, which is drawn from the solar collector using a recirculation pump, through a supply pipeline and a manifold and through thermostatic solenoid valves, controller control and the heating medium is returned to the solar collector in a closed circuit.

The storage method according to the invention is characterised in that the outer surface of the side walls and the soil layers adjacent to the energy storage are heated by the outer heating pipeline. Heating medium with temperature lower than the filling temperature inside the storage space is fed to the aforementioned heating pipeline.

In a preferable embodiment according to the invention, the reinforced concrete layer of the side walls of the thermal energy storage is heated by the heating pipeline of the reinforced concrete, using heating medium from the solar collector, in a closed circuit.

The object of the solution according to the invention is shown in an embodiment in the attached drawing, in which individual figures of the drawing represent as follows: Fig. 1 - a perspective view of a cross-section of the thermal energy storage, including the heating pipeline systems.

Fig. 2 - a cross-section through a part of the storage according to Fig. 1.

Fig. 3 - a diagram of the storages supply system according to Fig. 1.

Fig. 1 shows a perspective view of a cross-section through the thermal energy storage, schematically depicting the heating pipeline systems. In this embodiment, the thermal energy storage 1 is a cuboid including four side walls 2, a base 3 and a lid 4. The side walls 2, the base 3 and the lid 4 separate a fragment of soil comprising the filling accumulating heat. In other embodiment, the separated soil fragment may be removed and replaced with a different heat accumulating material.

The structure of all side walls 2 is identical. Fig. 1 shows a transparent view of the storage 1, depicting the heating pipeline systems 7, 8, 9 with the heating medium. The thermal energy storage 1 contains filling 5 as a thermal energy accumulating material. This heat accumulating filling 5 is better shown in Fig. 2. In this embodiment, the heat accumulating filling 5 is the separated fragment of soil, in which the walls of the storage 1 are placed. In other embodiments, the filling 5 may be sand, gravel, rock and other similar solid, semi-liquid or liquid materials able to accumulate heat.

The thermal energy storage 1 includes in this embodiment three heating systems 7, 8, 9 including pipes releasing heat and supplied with a liquid heating medium from the known solar collector 6. Glycol is the heating medium in this embodiment. Each heating pipe system in this embodiment is a single line, thus, this embodiment includes three separate pipeline systems: the filling heating pipeline 7, the reinforced concrete layer heating pipeline 8 and the outer heating pipeline 9. In other embodiments, said pipelines 7, 8, 9 may be divided, with each including several loops, especially in the case of large thermal energy storage systems, where the flow resistance of the heating medium in a single pipeline 7, 8, 9 as a consequence of its length. The attached Fig. 1, Fig. 2 and Fig. 3 do not show the pipelines 7, 8, 9 as three continuous lines, because of the need to indicate that these pipelines are separate, which is possible once the storage system is shown as a cross-section. A connection of pipelines as such into separate circuits is generally known to persons skilled in the art. These circuits are supplied by separate circuits designated together as 11, via thermostatic solenoid valves designated together as 10. In order to simplify Fig. 1, three supplying and receiving pipelines are schematically shown as 11, and three thermostatic solenoid valves are schematically shown as 10, wherein each of the solenoid valves 10 supports one of the three pipelines 11 supplying one of the three heating pipelines 7, 8, 9. This is shown more accurately in Fig. 3 of the drawing.

The source of the heated heating medium is a membrane type solar collector 6, supplied through a manifold 12, thermostatic solenoid valves 10 and supplying pipelines 11, heating pipelines 7, 8, 9 with the heating medium, which is glycol in this particular embodiment. Water as heating medium may be used where the storage and the supplying pipelines are not exposed to frost.

Fig. 1 shows the storage according to the invention, including all three heating pipelines 7, 8, 9. In a different embodiment, the storage 1 may include only the heating pipeline 7 of the filling 5 and the outer heating pipeline 9. In another embodiment, the storage 1 may include only the heating pipeline 8 of the reinforced concrete layer 14.

In this embodiment, the storage is a cuboid fragment of soil, separated with side walls 2, the base 3 and the lid 4. The heating pipeline 7 of the filling 5 is placed in layers in this separated fragment of soil described as filling in this patent disclosure. In this embodiment, four layers of the heating pipeline 7 are present inside the filling 5, placed flat one on top of the other, at distances of 60 cm between the layers and combined into a single pipeline. The layout of the heating pipelines 7 is similar here to the layout of heating lines in floor heating systems, as shown in Fig. 1. Thanks to the flow of the heating medium from the solar collector 6, the heating pipeline 7 heats the ground comprising the filling 5 of the storage 1. The length of the edge of the storage is 2.5 metres in this embodiment. The side walls 2 and the lid 4 have layered structure. They are made of passive layers of inner insulation 13.1 and outer insulation 13.2 provided as panels made of thermal insulation material. In this embodiment, passive layers 13.1, 13.2 are polyurethane layers with closed cells, defined as PUR foam in the art.

The side walls 2 and the lid 4 of the energy storage 1 in this embodiment include three layers and an inner passive insulation 13.1 layer and an outer passive insulation 13.2 layer, between which the carrier layer 14 made of reinforced concrete is placed. This is shown in Fig. 1, Fig. 2 and Fig. 3. The listed carrier layer of reinforced concrete 14, the side walls 2 and the lid 4 of the storage include the heating pipeline 8 of the reinforced concrete layer 14. The loops of this heating pipeline 8 are spirally wound in this embodiment around said side walls 2, wherein the distance between the spiral heating pipelines 8 in the reinforced concrete layer 14 is 20 cm. Thus, the reinforced concrete layer 14 is a part of active insulation in this solution. In this patent disclosure, active insulation is defined as those wall layers of the storage 1 provided with heating pipelines 8, 9, which form a barrier preventing heat leakage from the storage 1 by heating these wall layers. In this embodiment, the heating pipeline 8 is placed horizontally in the lid 4 of the storage, in the reinforced concrete layer 14.

In a solution according to the invention, the third section of the heating pipeline is provided for and designated as the outer heating pipeline 9. As shown in Fig. 1 and Fig. 2, the outer heating pipeline is spirally wound around the outer surface of the passive insulation layer 13.2 of side walls 2 of the thermal energy storage. The distance between the spiral loops of this other heating pipeline 9 is 20 cm in this embodiment. In another embodiment, this heating pipeline 9, in particular in the case of a larger storage 1 , may include separate loops supplied in parallel from the manifold 12 of the heating medium, through a thermostatic solenoid valve 10 dedicated to individual loops.

In a solution according to the invention, the manifold 12 and the solenoid valves 10 include a known controller system 16 switching the heating medium supply from the solar collector 6 between the heating pipeline 7 of the storage filling, the heating pipeline 8 of the reinforced concrete layer 14 and the outer heating pipeline 9. Fig. 3 shows the storage supply system according to the invention in more detail. It shows a section of the top part of the storage 1 with the filling 5 as a fragment of the surrounding soil. The filling 5 provides an accumulator, from which, once heated, thermal energy can be drawn for utility purposes by known elements of a heat exchanger, not presented here. This figure shows the inner layer 13.1 of passive insulation, the carrier layer of reinforced concrete 14 and the outer layer 13.2 of passive insulation. The layers 13.1, 13.2 of passive insulation are polyurethane panels with closed cells. The reinforced concrete layer 14 includes lines of the heating pipeline 8 of this layer. Thus, the reinforced concrete layer 14 is an active insulation layer. As shown in Fig. 3, in this embodiment, multiple lines of the heating pipeline 8 are placed in the reinforced concrete layer 14 in all side walls 2, and in this embodiment, also in the lid 4. However, this is not required as heat of the filling 5 flows naturally upwards, namely towards the lid 4. In this embodiment, the heating pipelines 8 of the reinforced concrete layer 14 are connected in a known manner, into a single heating medium circuit. In other embodiments, the reinforced concrete layer 14 may not include a heating pipeline 8.

In the soil filling 5 of the thermal energy storage 1 there are lines of the heating pipeline 7 of this filling 5. In this embodiment, the lines 7 are routed through the filling 5 in layers, as shown in Fig. 1 and Fig. 2. The heating pipeline 7 in the filling 5 is routed in this embodiment in layers, similar to how floor heating lines are usually routed, and connected into a single heating medium supply circuit.

Another, third set of lines of the outer heating pipeline 9, is routed around the outer surfaces of the side walls 2. This line set includes loops, spirally wound around the outer surface of side walls 2 of the storage 1. They are placed on the outer surface of the outer passive insulation 13.2. In this embodiment, the loops of the heating pipeline 9 are routed as a spiral, at a distance of 20 cm between them, and connected into a single heating medium supply circuit. The outer heating pipeline 9 is used to heat the outer surface of the outer passive layer 13.2, and mainly the soil layers adjacent to this layer and surrounding the storage 1. Even a slight increase in temperature of such adjacent soil layers, the heat flow from the storage to such soil layers surrounding the storage 1 is significantly limited.

Fig. 3 shows that each of the heating pipelines 7, 8, 9 is supplied with a heating medium from a dedicated supplying pipeline 11. Thus, three supplying pipelines 11 are connected through three dedicated solenoid valves 10. The heating medium returns from the heating pipelines 7, 8, 9 to the solar collector 6 as a result of operation of the recirculation pump 15 in the system, in a known system returning the heating medium to the collector, in a closed circuit. The term dedicated solenoid valve 10 means here that each of the supplying pipelines 11 is supported by one of the three solenoid valves 10, as shown in this Figure.

The solenoid valves 10 cooperate with the manifold 12 controlled by the controller 16, one input of which is connected to the temperature sensor 17 of the heating medium at the output from the solar collector, while the other input is connected to the temperature sensor 18 of the heating medium at the return from the storage 1 to the collector 6. The controller 16 controls the supply of the heating pipelines 7, 8, 9 from the manifold 12. The heating medium circulation in the described system is forced by the action of the recirculation pump 15 controlled by the known controller 16.

According to the invention, the standard supply of the heating medium includes the heating pipeline 7 of the filling 5. In a solution according to the invention, also the carrier layer of reinforced concrete 14 has been provided with an independent, additional heating pipeline 8, which caused this layer of reinforced concrete 14 between the passive insulation layers 13.1 and 13.2 to become an active insulation layer, additionally blocking the flow of thermal energy from the storage 1. It was found that the expenditure of heat supplied by the heating medium to the reinforced concrete layer 14 is small, as this layer 14 is located between the layers 13.1 and 13.2 of the passive insulation, while the use of this type of active insulation significantly improved the ability of the storage 1 to retain and accumulate heat.

Another element of the solution according to the invention is the outer heating pipeline 9. It is wound around the outer surface of the storage 1, around the outer passive insulation layer 13.2 and continuously contacts the soil surrounding the storage 1. The heating pipeline 9 is supplied with the heating medium during the periods of time, when parameters of the heating medium from the solar collector 6 reach values below those required for thermal energy accumulation in the storage 1. The outer heating pipeline 9 is thus supplied when the temperature of the heating medium received from the collector 6 is lower than the filling temperature of the storage 1. In known solutions, the controller stops the operation of the recirculation pump 15 during such periods. In order to implement this task, a temperature sensor 17 of the heating medium was proposed at the collector 6 outlet and a temperature sensor 18 of the filling 5.

In a solution according to the invention, when the temperature of the heating medium decreases below the temperature of the filling 5, the flow of heating medium through the collector 6 is not stopped, but directed through the manifold 12 and the dedicated solenoid valve 10 to the outer heating pipeline 9, where even low temperature of this heating medium increases the temperature of soil surrounding the storage, thus facilitating the blocking of flow of thermal energy from the filling 5 to the soil surrounding the storage 1.

When the temperature of the heating medium exceeds those of the storage filling, the heating medium is routed through the controller 16, the manifold 12 and dedicated solenoid valves 10 again to the heating pipelines 7, 8, while its flow in the outer heating pipeline 9 is stopped. This makes use of the heat of the heating medium with parameters adequate for effective supplying of the heating pipelines 7, 8, while still adequate to increase the temperature of the soil directly surrounding the storage 1.

The method for storing thermal energy is characterised in that the filling 5 of the thermal energy storage 1 is heated by the heating pipeline 7 using the heating medium. The heating medium is drawn using the pump 15 from the solar collector 6 in a closed circuit, through the supply pipeline 11, the manifold 12 and through the thermostatic solenoid valves 10.

System operation is controlled by the controller 16. The heating pipeline 8 heats the carrier layer of the reinforced concrete 14 of the side walls 2 and of the lid 4 of the thermal energy storage 1. Heating medium with a temperature lower than that of the filling 5 is used in the outer heating pipeline 9 to heat the outer surface of the side walls 2 and the layer of soil surrounding the storage 1. The heating pipeline 9 uses heating medium with temperature lower than the temperature of filling 5 of the storage 1.

List

used in the

1. Thermal energy storage.

2. Side wall 3. Base

4. Lid.

5. Filling.

6. Solar collector. 7. Heating pipeline of the filling.

8. Heating pipeline of the reinforced concrete layer.

9. Outer heating pipeline.

10. Thermostatic solenoid valve.

11. Supplying pipeline. 12. Manifold.

13. 1. Inner layer of passive insulation.

13.2. Outer layer of passive insulation.

14. Reinforced concrete layer.

15. Recirculation pump. 16. Controller.

17. Temperature sensor.

18. Temperature sensor.

Claims

Claims.

1. A thermal energy storage containing, inside a space separated with side walls (2), the base (3) and the lid (4), a filling (5) accumulating thermal energy, wherein inside the filling (5) at least one heating pipeline (7) of the filling (5) is routed in layers, wherein the side walls (2) of the storage (1) have layered structure and between the inner passive insulation layer (13.1) and the outer passive insulation layer (13.2) at least one carrier layer of reinforced concrete (14) is present, wherein the heating pipeline (7) of the filling (5) is connected with at least one supplying pipeline (11) with a solar collector (6) via a manifold (12) and with at least one thermostatic solenoid valve (10) and with a return pipeline, as well as with a controller (16) controlling the recirculation pump (15) of the heating medium circuit, characterised in that the side wall (2) with a different layer structure contains an active insulation system comprising at least one set of heating pipes supplied with a heating medium from the solar collector (6) via the supplying pipeline (11), through at least one solenoid valve (10) and a manifold (12).

2. Energy storage according to Claim 1, characterised in that the active insulation system includes, around the outer passive insulation layer (13.2), around the side walls (2) of the energy storage (1), at least one outer heating pipeline (9) connected with the solar collector (6) via at least one supplying pipeline (11), a manifold (12) and at least one thermostatic solenoid valve (10).

3. Energy storage according to Claim 1 or 2, characterised in that the active insulation system includes at least one heating pipeline (8) in a reinforced concrete layer (14) inside the side walls (2), connected with the solar collector (6) via at least one supplying pipeline (11), a manifold (12) and at least one thermostatic solenoid valve (10).

4. An energy storage according to Claim 1 or 2, characterised in that the lid (4) of the storage (1) includes at least one heating pipeline (8) routed through the reinforced concrete layer (14). Storage according to Claim 2 or 3 or 4, characterised in that the heating pipe systems in the heating pipeline (8) of the reinforced concrete layer (14) and in the outer heating pipeline (9) are parallel in each of those pipelines (8, 9). Storage according to Claim 1, characterised in that the heating pipelines (7, 8, 9) include at least one pipeline system each, independently supplied with the heating medium. A method for storing thermal energy characterised in that the filling of the thermal energy storage is heated using the heating pipeline (7) of the filling (5) with the heating medium, which is drawn by a recirculation pump (15) from the solar collector (6) using at least one supplying pipeline (11), through the manifold (12) and through at least one thermostatic solenoid valve (10), controlled by a controller (16) and this heating medium is returned in a closed circuit to the solar collector (6), characterised in that the outer surface of the side walls (2) and soil layers adjacent to the energy storage (1) are heated by the outer heating pipeline (9), wherein heating medium at a temperature lower than the temperature of the filling (5) inside the storage (1) is fed to said heating pipeline (9). A method for storing according to Claim 7, characterised in that the reinforced concrete layer (14) of the side walls (2) of the thermal energy storage (1) is heated by the heating pipeline (8) of the reinforced concrete, using heating medium from the solar collector (6), in a closed circuit.