Heat energy storage system

Abstract

The invention relates to a thermal energy storage system comprising a container having a phase change material (PCM) and a heat exchange coil interacting with the phase change material. Coil tubes are easy to produce and assemble in the system, including a plurality of internal channels for conveying a heat exchange fluid and providing a large heat transfer surface area. The invention also relates to a method of manufacturing coils by extrusion, and to a method of assembling said system.

Description

Technical Field

[0001] The present invention relates to a thermal energy storage system and a method of manufacturing the system. Background Art

[0002] About half of the energy consumed by industry and buildings is thermal energy (heat or cooling). Process industries, the food and beverage industry, and building owners are often faced with large daily fluctuations in heating and / or cooling energy demand. Therefore, oversized heating / cooling systems are needed to handle peak demands with a high dynamic operating range to cope with the fluctuations. In addition, if the instantaneous energy demand reaches the maximum capacity of the power grid or district heating network, the industrial sector may have to limit production capacity to avoid energy interruptions. In addition, peak loads lead to a significant increase in energy bills, because not only the total energy consumption, but also the energy price is related to the electricity demand.

[0003] Implementing thermal energy storage (TES) can address peak energy demands, especially peak demand for heat. According to the International Energy Agency, thermal energy storage is key to managing the industry's heat and electricity needs more flexibly, reliably and sustainably. Integrated thermal energy storage devices used as thermal batteries are an effective solution to separate the production of heat (or cooling) from the use of heat (or cooling), with two benefits: (1) better management of energy use by providing additional heat during peak demand periods; and (2) improved cost-effectiveness whenever there is a mismatch between energy production and demand.

[0004] Thermal energy storage devices form complex structures with many internal components and may be expensive to produce and assemble. The object of the present invention is to provide a simple and efficient thermal energy storage system comprising a smaller number of internal components. In addition, the present invention provides a simple, robust and efficient heat exchange coil that is easy to produce and install in a thermal energy storage system, requiring only fewer welding points, thereby extending the life of the heat exchanger and reducing maintenance costs. Fewer welding points reduce the risk of leakage. If the heat exchange fluid is mixed with the phase change material fluid, the phase change material will be contaminated and the efficiency will be reduced. In addition, leakage may produce acidic and highly corrosive components that may damage the internal components of the thermal energy storage system.

[0005] Another object of the present invention is to provide a thermal energy storage system that can be easily scaled up by extrusion without significantly increasing the number of welds. By extruding the heat exchanger coil of the present invention, it is easy to adjust the proportional parameters, such as the shape parameters, length and width. Moreover, the present invention is easy to assemble and provides a lightweight structure, which is beneficial in environments such as freight containers and ships where weight requirements are low.

[0006] Furthermore, with aluminum produced using a CO2-free process, using aluminum instead of alternative heat exchanger materials such as stainless steel will result in a lower CO2 footprint for the entire heat exchanger. Since aluminum has a higher thermal conductivity, its heat transfer performance is also higher.

[0007] US6101821A describes an ice-on-coil (IOC) ice storage coil system and method using "deep trough" technology. The main features include a serpentine tubular coil whose vertical height is greater than the horizontal width, ensuring efficient formation of ice columns in the ice storage tank. In addition, the refrigerant supply and return manifolds are located at the upper end of the coil to facilitate maintenance, assembly, leak inspection or repair. In some embodiments, the coil is not horizontal, but uses vertical or inclined tubes to help remove air during filling with the coolant mixture.

[0008] CN107860255A relates to a heat storage device and an air conditioner. The heat storage device is composed of a body module and a heater, wherein the body module contains a phase change heat storage material. The heater is responsible for heating the phase change heat storage material. Summary of the invention

[0009] The present invention relates to a thermal energy storage system having a container forming an internal volume, a hollow heat exchange coil located inside the container, wherein the heat exchange coil is used to transport a coil fluid inside; an inlet fixed to the wall of the container, wherein the inlet is connected to the coil fluid; and an outlet fixed to the wall of the container, wherein the outlet is connected to the coil fluid. During operation, the internal volume is at least partially filled with a phase change material surrounding at least a portion of the coil. The coil includes a plurality of internal channels for transporting a coil fluid forming a certain thickness, and the coil has an elongated cross-section, a certain height and width.

[0010] The present invention also relates to the thermal energy storage system, wherein the coil is made of aluminum or an aluminum alloy.

[0011] The present invention also relates to the thermal energy storage system, wherein the coil has a curved section in a U-shape, or wherein the coil has a plurality of curved sections in a serpentine shape, and wherein each curved section has a curvature radius.

[0012] The invention also relates to the thermal energy storage system, wherein the inlet and the outlet are fixed to the same container wall of the container, or wherein the inlet and the outlet are fixed to different container walls of the container.

[0013] The present invention also relates to the thermal energy storage system, wherein the coil fluid is a gas, such as air, steam, CO2, butane, propane, ammonia or a combination of the foregoing.

[0014] The present invention also relates to the thermal energy storage system, wherein the coil fluid is a liquid, such as water, ethylene glycol, CO2, liquid ammonia, butane, oil, propane or a combination of the foregoing.

[0015] The present invention also relates to the thermal energy storage system, wherein the phase change material is one of water, hydrated salt, organic compound, sugar alcohol, paraffin, ester, high-density polyethylene and eutectic mixture or a combination thereof.

[0016] The invention also relates to a thermal energy storage system as described, wherein each internal channel has a circular, oval, rectangular or square cross-section.

[0017] The invention also relates to the thermal energy storage system, wherein the coil has an aspect ratio between 3:1 and 2000:1.

[0018] The present invention also relates to the thermal energy storage system, wherein the coil has a height of 1-4 mm and a width of 10-2000 mm.

[0019] The present invention also relates to the thermal energy storage system, wherein the radius of curvature is 5-25 mm, the width is 10-2000 mm, and the height is 1-4 mm.

[0020] The present invention also relates to the thermal energy storage system, wherein the ratio of the height to the thickness of the coil is between 2:1 and 20:1.

[0021] The invention also relates to the thermal energy storage system, wherein the ratio between the total cross-sectional area (A2) of the internal channel and the cross-sectional area of ​​the coil is between 1:4 and 4:1.

[0022] The invention also relates to a method for manufacturing a hollow heat exchange coil according to any one of the preceding claims by extrusion.

[0023] The invention also relates to said method, wherein said coil is extruded in aluminium or an aluminium alloy.

[0024] The invention also relates to a method of assembling a thermal energy storage system according to any one of the preceding claims, comprising the following steps:

[0025] - providing an inlet and securing said inlet to said container wall;

[0026] - providing an outlet and securing said outlet to said container wall;

[0027] - introducing the coil into the container;

[0028] - Fix one end of the coil to the inlet and the other end to the outlet. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a side view of an embodiment of the present invention;

[0030] Figure 2 is a side view of an embodiment of the present invention;

[0031] Figure 3 is a side view of an embodiment of the present invention;

[0032] Figure 4 is a cross-sectional view of a heat exchange coil according to an embodiment;

[0033] Figure 5 is a cross-sectional view of a heat exchange coil according to an embodiment. DETAILED DESCRIPTION

[0034] Figure 1 It is a side view of an embodiment of the present invention. Figure 1 A thermal energy storage (TES) system 10 is shown having a container 100 forming an interior volume 101. The thermal energy storage system 10 further comprises at least one heat exchange coil 200 located within the interior volume 101. Preferably, the coil 200 is made of aluminum or an aluminum alloy.

[0035] The container 100 is at least partially filled with a phase change material (PCM) 300 surrounding at least a portion of the heat exchange coil 200. Ideally, the phase change material 300 is one or a combination of water, hydrated salts, organic compounds, sugar alcohols, paraffin waxes, esters, high-density polyethylene, and eutectic mixtures. Preferably, the container is filled with the phase change material 300 so that the coil 200 is completely immersed in the phase change material 300.

[0036] One end of the heat exchange coil 200 is connected to an inlet 120 fixed to the container wall, and the other end is connected to an outlet 121 also fixed to the container wall. The inlet 120 and the outlet 121 may be fixed to or form part of at least one distribution header (not shown).

[0037] exist Figure 1 In the embodiment, the inlet 120 and the outlet 121 are fixed to the same container wall, but other figures show different variations. The heat exchange coil 200 is a hollow element (see Figure 4 ), having at least one internal delivery channel 220 for delivering coil fluid 230. One or more channels extend like holes inside, so that the coil 200 can deliver the fluid 230 from the inlet 120 to the outlet 121 inside, while achieving conductive heat exchange between the fluid 230 and the phase change material 300. The coil 200 is used to provide a large surface area, through which the coil fluid 230 interacts with the phase change material 300 via the coil 200 material.

[0038] The inlet 120 and the outlet 121 are fluidly connected to external sources and components, including pumps, for pressurizing and thereby delivering fluid through the coiled tubing 200 during operation.

[0039] The coil 200 may have a plurality of curved sections 400 in a serpentine or S-shape, wherein each curved section 400 has a radius of curvature R. The advantage of this shape is that the thermal energy storage system 10 may include only a single (or at least very few) internal heat exchange components that are easy to produce and assemble and cover most of the internal volume 101 .

[0040] The heat exchange coil 200 can be easily formed in one length by extrusion, and has a simple and cost-effective manufacturing process.

[0041] Figure 2 It is a side view of an embodiment of the present invention. Figure 2 Shows Figure 1 Another configuration of the embodiment shown. Figure 2 In the embodiment, the coil 200 is S-shaped, and the inlet 120 and the outlet are installed on different container walls of the container 100.

[0042] Figure 3 It is a side view of an embodiment of the present invention. Figure 2 Shows Figure 1 Another configuration of the embodiment shown. Figure 2 In the embodiment, the coil 200 is U-shaped, and the inlet 120 and the outlet are installed on the same container wall of the container 100.

[0043] Figure 4 2 is a cross-sectional view of a heat exchange coil 200 according to an embodiment. The coil 200 has a certain height H and a certain width W, wherein W is significantly greater than H. The ratio of the width W to the height H may be between 3:1 and 2000:1, and ideally, between 5:1 and 50:1. The height H may be 1-4 mm, and the width W may be 10-2000 mm.

[0044] Figure 4It is shown how the coil 200 can include an array of channels 220 that form an inner bore extending through the length of the coil 200 (not shown) for conveying a heat transfer fluid 230. The coil 200 can also include a single channel with an elongated cross-section. For example, the coil 200 can include 2 to 2000 channels. Due to the presence of the channels 220, the profile obtains a thickness parameter T that is substantially equal above and below each channel 220. The thickness parameter T is the distance between the upper or lower part of the channel 220 to the perimeter of the coil profile. The thickness parameter T represents the heat conduction distance and also indicates the rigidity of the coil 200. Ideally, the thickness T is as small as possible to promote heat transfer, but thick enough to withstand internal pressure and bending moments and strains.

[0045] At least one channel 220 is adapted to transport the heat exchange coil fluid 230 to and from an external source. The coil fluid 230 may be a gas, such as air, CO2, butane, propane, or a combination thereof. The coil fluid 230 may also be a liquid, such as water, ethylene glycol, CO2, liquid ammonia, butane, oil, propane, or a combination thereof.

[0046] Figure 4 The channels 220 mentioned in the embodiment are circular, although the channels can be deformed differently. They can also be elliptical. Figure 4 In the illustrated embodiment, each channel has a substantially equal diameter and they are arranged adjacently in a row with substantially equal distances from each other, although the distances between the channels 220 may vary. Figure 4 In the embodiment, the channels 220 are perfectly placed in a straight line, wherein the center of each channel is aligned along the same horizontal axis (not shown). The coil 200 may be formed of a lightweight, strong and thermally conductive material such as aluminum or an aluminum alloy.

[0047] The geometry of the coil 200 profile forms a middle section 250 between the channels 220 having a width D and a height H. The middle section acts as a support post and prevents the internal bore(s) from collapsing when the coil 200 is compressed and bent to form the curved section 400. This is advantageous because the channel maintains its cross-sectional area A2 throughout the curved section 400.

[0048] The number of channels 220 will depend on the profile width W and height H. An object of the present invention is to provide as large an internal flow area as possible while providing a profile thick enough to support the pressure of the fluid circulating in the coil 200 .

[0049] In one embodiment, the coil 200 includes only a single rectangular interior passage 220 that maximizes the interior flow area A2.

[0050] The coil 200 has an upper surface 240 and a lower surface 241, each having a certain width W and a certain length L (not shown) equal to the total length of the coil 200. The upper surface 240, the lower surface 241 or the side surface may include an engraved pattern or include grooves. The coil 200 profile acts as a series of joined tubular coils, instead providing a single coil with a large upper surface 240 and a large lower surface 241 for heat exchange, rather than having a series of tubular coils that must be manufactured separately and assembled separately.

[0051] Figure 5 2 is a cross-sectional view of a heat exchange coil 200 according to an embodiment. In addition to the channel 220 having a substantially rectangular profile, Figure 5 Examples and Figure 4 The channel 220 may also have a square profile. Compared with a circular or elliptical profile, a square or rectangular profile may increase the flow area within each coil 200.

[0052] Figure 6 is a perspective view of a heat exchange coil 200 according to the present invention. Figure 6 The embodiment includes a plurality of heat exchange coils 200 (as described above), however, the present invention may also include only one heat exchange coil 200, preferably with a wide and slender profile. Therefore, the present invention may include at least one heat exchange coil 200. Figure 6 In the embodiment, the first end 280 of the heat exchange coil 200 is connected to a port 280' (not shown) located on a first header 300. A header may also be referred to as a header. Further, the second end 281 of the heat exchange coil 200 is connected to a port 281' (not shown) located on a second header 301. The first header 300 includes a fluid inlet 120 fluidly connected to each port 280' of the first header 300. The second header 301 includes a fluid outlet 121 fluidly connected to each port 281' of the second header 301. The heat exchange coil 200 extends substantially perpendicular to the headers 300, 301.

[0053] Figure 6 The components constitute a fluid delivery system, which is ready to be deployed in the container 100 of the present invention (see Figure 1 ). Each heat exchange coil 200 may be made of metal extrusion and then connected to the corresponding ports on the first and second headers 300, 301 by, for example, brazing or welding. Figure 6The assembly is placed in the container 100 of the present invention, and the headers 300, 301 are fixed and connected to the same or different container walls (not shown) of the container 100, so that the coil fluid 230 from the external source can pass through the container wall, through the first header 300, further through each heat exchange coil 200, further through the second header 301, through the container wall and out of the container 100. Typically, the inlet 120 and the outlet 121 are connected to the same wall or opposite walls of the container 100 to improve the fluid flow through the coil 200.

[0054] The elongated shape of the coil 200 is one of the key features of the present invention. This shape is particularly advantageous because it provides a flat surface on which sensors or connection devices can be easily mounted. This surface is more accessible and user friendly than the cylindrical profile of conventional tubular coils.

[0055] In practical terms, this means that it is much easier and faster to mount a sensor or connection device to the coil 200 than in previous designs. For example, with an ultrasonic sensor located within the vessel, the sensor can simply be fixed to a flat surface of the coil 200 without any undue complexity. The charge state of the phase change material in the vessel can thereby be effectively and efficiently measured.

[0056] In general, the slender profile of the coil 200 is a key innovation of the present patent application, which facilitates the installation and use of sensors or connection devices. By making containers more accessible and easier to operate, the present invention is expected to enhance the functionality and usability of phase change materials, providing important benefits in a range of practical applications.

[0057] exist Figure 6 In the embodiment, the assembly direction is adjusted so that the headers are vertically aligned, i.e. upright. When the direction is adjusted, the headers 300, 301 are usually fixed and connected to the bottom container wall (not shown) and / or the top container wall (not shown).

[0058] You can also adjust Figure 6The direction of the group is such that the headers 300, 301 extend horizontally. When adjusting the direction, the headers 300, 301 will be fixed and connected to a first side wall (not shown) of the container 100 and / or another side wall (not shown) of the container 100. By vertically aligning the headers 300, 301, the coils 200 are horizontally aligned. By horizontally aligning the headers 300, 301, the coils 200 are vertically aligned. By vertically aligning the coils 200, the moment force applied at the connection point between the headers 300, 301 and the coils 200 is smaller than when the coils 200 are horizontally aligned, which is an advantageous aspect. When the coils are horizontally oriented, an auxiliary support structure may be provided to reduce the moment force, for example by connecting the coils 200 at different locations to a nearby container wall (not shown). Alternatively, a support column fixed to the bottom wall of the container may be connected to each coil 200.

[0059] The number of coils 200 determines the number of welding or connection points with the headers 300, 301. Therefore, the present invention may include only a single or only a few coils 200 with a wide profile (see Figure 4 ).

[0060] Figure 6 The assembly provides a simplified modular heat exchange system that can be easily installed on the container 100. The container 100 is filled with a phase change material so that at least one heat exchange coil 200 is at least partially in contact with the phase change material (not shown). Figure 6 When the system is assembled, the heat exchange coils 200 can be simultaneously connected to the headers 300, 301 by melting or providing a molten or adhesive material to each port 280, 281, and then each coil 200 is fixed to its corresponding port on the header 300, 301. The present invention provides a quick and effective way to assemble a heat exchange system.

Claims

1. A thermal energy storage system (10), comprising: a container (100) forming an interior volume (101); A heat exchange coil (200) located inside the container (100), characterized in that the heat exchange coil (200) is used to transport coil fluid (230) inside; Wherein, the heat exchange coil 200 is a single hollow element; an inlet (120) fluidly connected to the coil (200); an outlet (121) fluidly connected to the coil (200); Wherein, the inlet (120) is fixed on the container wall; Wherein, the outlet (121) is fixed on the container wall; wherein the inner volume (101) is at least partially filled with a phase change material (300) surrounding at least a portion of the coil (200); Wherein, when the container (200) is filled with the phase change material (300), the coil (200) is arranged to be completely immersed in the phase change material (300); wherein the coil (200) comprises an array of a plurality of internal channels (220) for conveying the coil fluid (230); wherein each channel (220) is used to transport the coil fluid (230) from the inlet (120) to the outlet (121); wherein the plurality of internal channels (220) provide a coil thickness parameter (T); The coil (200) has an elongated cross section, a certain height (H) and width (W), characterized in that W>H; wherein the coil (200) is serpentine or S-shaped with a plurality of curved segments (400), and wherein each curved segment (400) has a radius of curvature (R); At least one curved section (400) turns 180 degrees to form at least two parts of the coil (200) that are parallel to each other and have a constant distance (D1).

2. The thermal energy storage system (10) according to claim 1, further comprising: a first header (300) extending along the axis (z1) and comprising said inlet (120); a second header (301) extending along the axis (z2) and comprising the outlet (121); Wherein, the first end (280) of the coil (200) is connected to the corresponding port (280') of the first header (300), and the second end (281) is connected to the corresponding port (281') of the second header (301); wherein each coil (200) is in fluid communication with the first header and the second header (300, 301); wherein the first end (280) of the coil (200) extends longitudinally along the axis (z1); Wherein, the second end (281) of the coil (200) extends longitudinally along the axis (z2).

3. The thermal energy storage system (10) according to claim 1, comprising a plurality of coils (200), wherein the coils (200) have a certain distance (D2) between each other.

4. The thermal energy storage system (10) according to claim 2, comprising a plurality of coils (200), wherein the coils (200) have a certain distance (D2) between each other.

5. The thermal energy storage system (10) according to claim 1 or 3, in, The inlet (120) and the outlet (121) are accessible from outside the container (100); wherein the inlet (120) and the outlet (121) are connected to the same container wall of the container (100), or wherein the inlet (120) and the outlet (121) are connected to different container walls of the container (100).

6. A thermal energy storage system (10) according to any one of the preceding claims, characterised in that Each coil (200) extends along the horizontal plane of the container (100).

7. A thermal energy storage system (10) according to any one of the preceding claims, characterised in that Each coil (200) extends along a vertical surface of the container (100).

8. A thermal energy storage system (10) according to any one of the preceding claims, characterised in that The phase change material (300) is one of water, hydrated salt, organic compound, sugar alcohol, paraffin, ester, high-density polyethylene and eutectic mixture, or a combination thereof.

9. A thermal energy storage system (10) according to any one of the preceding claims, characterised in that Each internal channel (220) has a circular, oval, rectangular or square cross-section.

10. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that Each coil (200) has a width (W) to height (H) ratio between 3:1 and 2000:

1.

11. A thermal energy storage system (10) according to any one of the preceding claims, characterised in that Each coil (200) has a height (H) of 1-4 mm and a width (W) of 10-2000 mm.

12. The thermal energy storage system (10) according to any one of the preceding claims 3 to 9, characterized in that The curvature radius (R) is 5-25 mm, the width (W) is 10-2000 mm, and the height (H) is 1-4 mm.

13. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that The ratio of the height (H) to the thickness (T) of each coil (200) is between 2:1 and 20:

1.

14. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that The ratio between the total cross-sectional area of ​​the internal passage (A2) and the cross-sectional area of ​​the coil (A1) is between 1:4 and 4:

1.

15. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that Each coil (200) is made of aluminum or an aluminum alloy.

16. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that The coil fluid (230) is a gas, such as air, steam, CO2, butane, propane, ammonia or a combination thereof.

17. The thermal energy storage system (10) according to any one of claims 1 to 15, characterized in that: The coil fluid (230) is a liquid, such as water, ethylene glycol, CO2, liquid ammonia, butane, oil, propane or a combination thereof.

18. Thermal energy storage system (10) according to any one of the preceding claims, characterized in that At least one sensor is connected to the outer surface along the width (W) direction of the coil (200).

19. Method for manufacturing a heat exchange coil (200) according to any one of the preceding claims by extrusion; It is characterized in that The method comprises the step of bending the coiled tube (200) to form the plurality of bent segments (400).

20. The method for manufacturing a hollow heat exchange coil (200) according to claim 19, wherein the coil (200) is made by extrusion of aluminum or an aluminum alloy.

21. A method of assembling a thermal energy storage system (10) according to any one of the preceding claims 1 to 18, comprising the following steps: Providing at least one heat exchange coil (200); placing at least one heat exchange coil (200) at least partially within the container (100), and immersing at least a portion of the heat exchange coil (200) in a phase change material (300); Each heat exchange coil (200) is fluidly connected to a coil fluid (130) inlet (120) and a coil fluid (230) outlet (121), so that the coil fluid (230) can flow from the inlet (120) through each coil (200) to the outlet (121).

22. A method of assembling a thermal energy storage system (10) according to claim 21, comprising: Providing a first header (300) and a second header (301); Connecting the first end (280) of each coil (200) to a corresponding port (280') of the first header (300); Connecting the second end (281) of each coil (200) to a corresponding port (281') of the second header (301); in, The coil (200) and the headers (300, 301) are preassembled as separate components before being placed in the container (100).

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