Single-tank thermocline energy storage device

Abstract

The invention relates to a single-tank thermocline energy storage device which comprises a solid packed bed, the solid packed bed comprises at least three axially-distributed flow collecting and distributing devices and metal phase change materials located among the flow collecting and distributing devices, the metal phase change materials are graphite wrapped metal, and the metal is aluminum or aluminum alloy; in the heat storage process, fused salt flows in from the top, heat is transferred to the metal phase change material downwards layer by layer, and then the fused salt is led out from the flow collecting and distributing device; in the heat release process, the fused salt flows in from the bottom, heat is transferred to the fused salt from the upward metal phase change material layer by layer, and then the fused salt is led out from the flow collecting and distributing device. According to the single-tank thermocline energy storage device, through the arrangement of the at least three flow collecting and distributing devices, the fused salt is led out downwards layer by layer in the heat storage process and led out upwards layer by layer in the heat release process, the time for stabilizing the temperature of the fused salt at an outlet can be effectively prolonged, the thickness of a thermocline is controlled, and the efficiency and reliability of the single-tank thermocline energy storage device are improved.

Description

Technical Field

[0001] The present invention relates to an energy storage device, and more particularly to a single-tank thermocline energy storage device. Background Art

[0002] The single-tank thermocline energy storage device stores and releases heat in a single tank through a heat transfer medium and a packed bed material. During operation, through appropriate operation strategies, the high-temperature fluid and the low-temperature fluid can be spatially separated in the tank through the thermocline layer. A technical difficulty currently faced by the single-tank thermocline energy storage device is that after multiple cycles of heat storage and heat release, the thermocline layer will diffuse axially. The thickness of the diffused thermocline layer gradually increases, which not only reduces the heat storage capacity factor of the entire device, but also, when the situation is serious, the high-temperature fluid and the low-temperature fluid in the entire tank will mix, and the outside world may not be able to use the heat energy of the energy storage device. In addition, the existing packed beds mostly use sensible heat storage such as rocks or sand as the medium for storing heat, but their heat storage density is low, and the thermocline layer is also prone to axial heat diffusion during the heat storage and heat release process, resulting in a decrease in the heat storage capacity factor.

[0003] There have been related studies using inorganic phase change media to increase the heat storage density, such as graphite-wrapped molten salt, steel shell-wrapped paraffin, etc. as phase change materials placed in a single-tank thermocline energy storage device. In this way, not only can the heat storage density of the device be increased, but also the time for the temperature at the outlet of the packed bed to stabilize can be extended during a single heat storage and heat release process. However, the thermal conductivity of inorganic phase change materials is very low, resulting in a long heat exchange time. The phase change of the inorganic phase change medium from solid to liquid during the heat storage process, and the phase change from liquid to solid during the heat release process, both take a long time, which makes the thermocline layer inevitably increase. Although this phase change material can improve the power density of the energy storage device to a certain extent, due to the long heat exchange time and the increase in the thickness of the thermocline layer, there is a risk of axial diffusion of the thermocline layer. If not controlled, when the thermocline layer diffuses to the axial direction of the entire packed bed, the stored heat will be difficult to be effectively utilized. What is more serious is that the density of the inorganic phase change material will change with the operating temperature, causing its volume to change, thereby affecting the pressure change inside the cladding, which can easily cause the phase change material to leak into the heat transfer medium. Summary of the invention

[0004] In order to solve the technical problem of axial diffusion of the thermocline layer after multiple heat storage and release cycles in the above-mentioned prior art, the present invention provides a single-tank thermocline energy storage device.

[0005] According to the single-tank thermocline energy storage device of the present invention, it includes a solid packed bed, which includes at least three axially distributed collectors and diverters and a metal phase change material located between the collectors and diverters, wherein the metal phase change material is a graphite-wrapped metal, and the metal is aluminum or an aluminum alloy; during the heat storage process, the molten salt flows in from the top, transfers heat to the metal phase change material layer by layer downwards, and then is drawn out from the collectors and diverters; during the heat release process, the molten salt flows in from the bottom, transfers heat to the molten salt layer by layer upwards, and then is drawn out from the collectors and diverters.

[0006] In a preferred embodiment, the solid packed bed includes a first metal phase change material and a second metal phase change material, the first metal phase change material is located above the second metal phase change material, and the phase change temperature of the first metal phase change material is higher than the phase change temperature of the second metal phase change material.

[0007] In a preferred embodiment, the solid packed bed further comprises a non-metallic phase change material.

[0008] In a preferred embodiment, different metal phase change materials or non-metal phase change materials are separated by a current collector and divider.

[0009] In a preferred embodiment, the current collector and splitter is a concentric ring structure.

[0010] In a preferred embodiment, the connection head of the current collector and splitter is close to the center of the concentric rings.

[0011] In a preferred embodiment, the metal phase change material is in the shape of a sphere or a cylinder.

[0012] In a preferred embodiment, the single-tank thermocline energy storage device also includes a heat source heat exchanger, a cold source heat exchanger and a molten salt pump, wherein the solid packed bed, the molten salt pump and the heat source heat exchanger are connected in series in sequence to form a cycle during the heat storage process, and the solid packed bed, the heat source heat exchanger, the cold source heat exchanger and the molten salt pump are connected in series in sequence to form a cycle during the heat release process.

[0013] In a preferred embodiment, the solid packed bed, the first valve, the molten salt pump, the second valve, the heat source heat exchanger and the third valve are connected in series in sequence to form a cycle during the heat storage process, and the solid packed bed, the heat source heat exchanger, the fourth valve, the cold source heat exchanger, the molten salt pump, the fifth valve and the sixth valve are connected in series in sequence to form a cycle during the heat release process.

[0014] In a preferred embodiment, the heat source heat exchanger is disposed on a pipeline directly connected to the solid packed bed and is located on a different pipeline from the second valve.

[0015] According to the single-tank thermocline layer energy storage device of the present invention, by setting at least three current collectors and diverters, during the heat storage process, the molten salt flows in from the top, and is led out layer by layer from different current collectors and diverters according to the principle of whether the heat storage threshold temperature is exceeded; during the heat release process, the molten salt flows in from the bottom, and is led out layer by layer from different current collectors and diverters according to the principle of whether the heat storage threshold temperature is exceeded, thereby extending the time for the outlet temperature to stabilize, effectively controlling the thickness of the thermocline layer, and improving the efficiency and reliability of the single-tank thermocline layer energy storage device. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the heat storage process of the single-tank thermocline energy storage device according to the present invention.

[0017] Figure 2 It is a schematic diagram of the heat release process of the single-tank thermocline energy storage device according to the present invention.

[0018] Figure 3 It is a schematic diagram of the parallel arrangement of cylindrical metal phase change materials of the solid packed bed of the single-tank thermocline energy storage device according to the present invention.

[0019] Figure 4 It is a schematic structural diagram of the second flow collector and diverter of the solid packed bed of the single-tank thermocline energy storage device according to the present invention.

[0020] Figure 5 It is a schematic structural diagram of the third current collector and splitter of the solid packed bed of the single-tank thermocline energy storage device according to the present invention.

[0021] Figure 6 It is a schematic diagram of the temperature change of the thermocline layer of a single-tank thermocline energy storage device with a single outlet according to the prior art.

[0022] Figure 7-Figure 11 It is a schematic diagram of the temperature change of the thermocline layer of the single-tank thermocline energy storage device with five outlets according to the present invention. DETAILED DESCRIPTION

[0023] The preferred embodiments of the present invention are given below in conjunction with the accompanying drawings and described in detail.

[0024] like Figure 1-Figure 2 As shown, the single-tank thermocline energy storage device according to the present invention includes a solid packed bed 1, a heat source heat exchanger 2, a cold source heat exchanger 3 and a molten salt pump 4, wherein the solid packed bed 1, the molten salt pump 4 and the heat source heat exchanger 2 are sequentially connected in series to form a cycle during the heat storage process, and the solid packed bed 1, the heat source heat exchanger 2, the cold source heat exchanger 3 and the molten salt pump 4 are sequentially connected in series to form a cycle during the heat release process.

[0025] In the present invention, the solid packed bed 1 includes four axially distributed collectors and diverters 11, 12, 13, 14 and a metal phase change material located between the collectors and diverters. It should be understood that the four collectors and diverters 11, 12, 13, 14 here are only examples and not limitations. During the heat storage process, the molten salt flows in from the top and is drawn out from the collectors and diverters 12, 13, 14 layer by layer; during the heat release process, the molten salt flows in from the bottom and is drawn out from the collectors and diverters 13, 12, 11 layer by layer. Compared with the prior art of double collectors and diverters, the thickness of the thermocline layer can be significantly reduced, the time for the outlet temperature to stabilize can be extended, and the efficiency and reliability of the single-tank thermocline layer energy storage device can be improved.

[0026] In the present invention, the metal phase change material is designed to be in the shape of a sphere or cylinder, preferably with a diameter of 3 cm to 6 cm. The spheres can be randomly stacked or regularly stacked, with face-centered cubic stacking being the most preferred, and their porosity can be as low as 25.95%. By effectively reducing the porosity, the amount of molten salt used can be effectively reduced and the volume of the phase change medium can be increased, thereby increasing the energy storage density. For cylindrical phase change materials, it is recommended to stack them in a parallel overlapping manner, such as Figure 3 As shown, its porosity can be as low as 21.46%, thereby further optimizing the porosity of the packed bed.

[0027] In the present invention, the metal phase change material is a graphite-wrapped metal, and the metal is aluminum or an aluminum alloy. In a preferred embodiment, the metal is pure aluminum. In another preferred embodiment, the metal is an Al (66%)-Mg (34%) alloy (melting point is 450°C). In another preferred embodiment, the metal is an Al (64.3%)-Cu (34.0%)-Sb (1.7%) alloy (melting point is 545°C). Using aluminum or aluminum alloy metal as a phase change material can greatly reduce the change in density during its phase change process, thereby reducing the change in pressure in the packaging material. In addition, using graphite as a packaging material can prevent aluminum metal or aluminum alloy from chemically reacting with the packaging material, thereby having good chemical stability. Moreover, graphite itself has a high thermal conductivity. The thermal conductivity of aluminum or aluminum alloy is above 50W / (m·K), which can significantly shorten the heat exchange time during heat storage and heat release compared with inorganic media with a thermal conductivity of 1-2W / (m·K), thereby reducing the thickness of the thermocline layer, improving the efficiency of the solid packed bed 1, and further improving the performance of the single-tank thermocline energy storage device. It should be understood that those skilled in the art can use graphite to encapsulate aluminum or aluminum alloy as needed, and the specific composition of the aluminum alloy can be adjusted according to the operating temperature of the thermocline layer. In addition, the thickness of the graphite shell of at least 3mm can also be selected as needed.

[0028] In the present invention, the solid packed bed 1 can include a variety of metal phase change materials as needed. In a preferred embodiment, the solid packed bed 1 includes a first metal phase change material at the top and a second metal phase change material at the bottom, and the phase change temperature of the first metal phase change material is higher than the phase change temperature of the second metal phase change material. This arrangement of phase change temperatures from top to bottom can optimize the control of the thermocline layer, reduce the diffusion of the thermocline layer, and increase the time for the outlet temperature to stabilize. During heat storage, the high-temperature interval extends downward layer by layer, and when the bottom outlet temperature rises to a certain temperature threshold, the heat storage process ends; during heat release, the low-temperature fluid interval extends upward layer by layer, and when the top outlet temperature drops to a certain temperature threshold, the heat release process ends. Since the high-temperature fluid is located at the top, placing the phase change material with a high phase change temperature at the top can extend the stabilization time of the top outlet temperature as much as possible when the heat release is near the end; and placing the phase change material with a low phase change temperature at the bottom can extend the stabilization time of the bottom outlet temperature as much as possible when the heat storage is near the end.

[0029] In the present invention, the solid packed bed 1 may also include non-metallic phase change materials, such as sensible heat storage materials. In a preferred embodiment, the solid packed bed 1 includes basalt located in the middle. In a preferred embodiment, the solid packed bed 1 includes basalt located between two metallic phase change materials. In another preferred embodiment, the solid packed bed 1 includes sand and gravel located below the metallic phase change material.

[0030] In the present invention, different metal phase change materials or non-metal phase change materials are separated by current collectors and diverters 12 and 13. A layer of material is defined between adjacent current collectors and diverters 11, 12, 13, and 14. The metal phase change material can occupy a single layer or at least two layers. The sensible heat storage material can occupy a single layer or at least two layers. The positions of the current collectors and diverters 12 and 13 in the solid packed bed 1 depend on the filling of different materials, and a current collector and diverter 12 and 13 are placed at the boundary of each layer of different materials.

[0031] In the present invention, the current collectors and diverters 11, 12, 13, and 14 are concentric ring structures. Each of the current collectors and diverters 11, 12, 13, and 14 has a connector 1001 for injecting and extracting molten salt. The connector 1001 of the current collector and diverter 11 is located at the center of the concentric rings, and the connectors 1001 of the current collectors and diverters 12, 13, and 14 are close to the center of the concentric rings to reduce the unevenness of fluid distribution while avoiding the overlap of the injection and extraction pipes, such as Figure 4 and Figure 5As shown. Each flow collector and diverter 11, 12, 13, 14 has a concentrically arranged inner ring 1003 and an outer ring 1004, which are interconnected through a radially extending flow guide tube. A number of flow diverters 1002 are arranged on the inner ring 1003 and the outer ring 1004 according to the equal arc distance of the molten salt in the ring. In this way, the molten salt entering the flow collector and diverter 11, 12, 13, 14 through the connector 1001 enters the inner ring 1003 and the outer ring 1004 in turn through the flow guide tube, and then is evenly distributed to the entire solid packed bed 1 through the flow diverter 1002.

[0032] In the present invention, the solid packed bed 1, valve 113, molten salt pump 4, valve 111, heat source heat exchanger 2 and valve 101 are sequentially connected in series to form a cycle during the heat storage process, and the solid packed bed 1, heat source heat exchanger 2, valve 114, cold source heat exchanger 3, molten salt pump 4, valve 112 and valve 104 are sequentially connected in series to form a cycle during the heat release process. In particular, the heat source heat exchanger 2 is arranged on a pipeline directly connected to the solid packed bed 1, and is located on a different pipeline from the valve 111.

[0033] like Figure 1 As shown, the heat storage process includes molten salt flowing into the solid packed bed 1 from the top and flowing out from the bottom. Valves 101, 111, and 113 are opened, and valves 106, 112, and 114 are closed. First, valves 103 and 104 are closed. The molten salt passes through the molten salt pump 4, and then passes through the heat source heat exchanger 2 and enters from the first collector and diverter 11 at the top through valve 101. After heat exchange with the solid packed bed 1, it is sucked out from the second collector and diverter 12, and then passes through valves 102, 105, and 113 to enter the molten salt pump 4. When the temperature of the molten salt passing through valve 102 is higher than the threshold, valve 102 is closed and valve 103 is opened. At this time, the molten salt in the solid packed bed 1 flows from the first collector and diverter 11, sucked out from the third collector and diverter 13, and then passes through valves 103, 105, and 113 to enter the molten salt pump 4, and then passes through valve 111 and the heat source heat exchanger 2 to complete the entire cycle. When the temperature of the molten salt passing through valve 103 exceeds the threshold, valve 104 is opened, and valves 103 and 105 are closed. At this time, the molten salt in the solid packed bed 1 flows into the first collector and splitter 11, is sucked out by the fourth collector and splitter 14, passes through valve 111 and the heat source heat exchanger 2, and completes the entire cycle. When the temperature passing through valve 104 exceeds the threshold, the heat storage process ends, and then heat release begins.

[0034] like Figure 2As shown, the heat release process includes molten salt flowing into the solid packed bed 1 from the bottom and flowing out from the top. Valves 105, 111, and 113 are closed, and valves 104, 112, and 114 are opened. Open valves 103 and 106, and close valves 101 and 102. After the hot molten salt passes through the cold source heat exchanger 3 for heat exchange, the cold molten salt passes through the molten salt pump 4, valve 112, and the fourth collector and diverter 14 to enter the solid packed bed 1 for heat exchange. The molten salt after heat exchange passes through the third collector and diverter 13 and valves 103 and 106, passes through the heat source heat exchanger 2 to take away the residual heat, enters the cold source heat exchanger 3 to transfer the heat to the cold side medium, and completes the whole cycle. When the temperature of the molten salt passing through valve 103 drops to the threshold, close valve 103 and open valve 102. At this time, the molten salt in the solid packed bed 1 flows into the fourth collector and diverter 14 and flows out of the second collector and diverter 12. When the temperature of the molten salt passing through valve 102 drops to a threshold value, valves 102 and 106 are closed, and valve 101 is opened. At this time, the molten salt in the solid packed bed 1 flows into the fourth collector and splitter 14 and flows out of the first collector and splitter 11. When the temperature passing through valve 101 is lower than the threshold value, the heat release process ends.

[0035] In this way, by controlling the operation of different collectors and diverters 11, 12, 13, and 14 through valves, the optimal optimization of the thickness of the inclined temperature layer under the temperature threshold control mode can be achieved. The temperature threshold is selected according to the type of molten salt and the operating temperature. In a preferred embodiment, the molten salt is a high-temperature chloride salt with an operating temperature between 700 and 435 degrees Celsius, and aluminum (660°C) and a low-temperature aluminum alloy (440°C) are used as metal phase change materials. In another preferred embodiment, the molten salt is a binary nitrate with an operating temperature between 290 and 565 degrees Celsius, and an aluminum alloy metal phase change material with a phase change temperature of about 510 to 550 degrees Celsius is used.

[0036] Example 1

[0037] Chloride salt (33.0wt% NaCl-21.6wt% KCl-45.4wt% MgCl 2 ) is the heat transfer medium, the operating temperature is 435℃~700℃. The end of the heat storage state is marked by the outlet temperature of the fourth collector and splitter 14 at the bottom rising to more than 460℃. The end of the heat release state is marked by the outlet temperature of the first collector and splitter 11 at the top falling to more than 660℃.

[0038] Pure aluminum is selected as a high-temperature phase change material with a phase change point of 661°C, and is placed between the first collector and diverter 11 and the second collector and diverter 12. Al (66wt%)-Mg (34wt%) alloy is used as a low-temperature phase change material with a phase change point of 450°C, and is placed between the third collector and diverter 13 and the fourth collector and diverter 14. Basalt with a porosity of 42% is filled between the second collector and diverter 12 and the third collector and diverter 13, and is randomly stacked with an equivalent diameter of 2cm. The aluminum metal phase change material at the top is stacked on the basalt in the form of long cylindrical strips, and the randomly stacked basalt is stacked in a long cylindrical phase change filling bed with a porosity of 30% at the bottom.

[0039] When storing heat, see Figure 1 , valves 106, 112, and 114 are always closed, valves 101, 111, and 113 are always open, and valves 102, 103, 104, and 105 are opened and closed in sequence according to the temperature of the chloride salt drawn out from the collectors and diverters 12, 13, and 14. Specifically, 700°C chloride salt enters the packed bed from the first collector and diverter 11 at the top inlet, and exchanges heat with the metal aluminum phase change medium wrapped in graphite. Low-temperature chloride salt is drawn out from the second collector and diverter 12. When the temperature of the chloride salt at the outlet of the second collector and diverter 12 exceeds 460°C, valve 102 is closed, valve 103 is opened, and low-temperature chloride salt is drawn out from the third collector and diverter 13. When the temperature of the chloride salt at the outlet of the third collector and diverter 13 exceeds 460°C, valves 103 and 105 are closed, valve 104 is opened, and low-temperature chloride salt is drawn out from the fourth collector and diverter 14. At this time, the high temperature chloride salt exchanges heat with the Al (66 wt%)-Mg (34 wt%) alloy at the bottom. When the outlet temperature of the fourth collector and splitter 14 exceeds 460° C., the heat storage state ends.

[0040] When releasing heat, see Figure 2 , valves 104, 112, 114 are always open. Valves 105, 111, 113 are always closed. Valves 101, 102, 103, 106 are opened and closed in sequence according to the temperature of the chloride salt drawn out from the collectors and diverters 13, 12, 11. Specifically, at the beginning, valves 103 and 106 are opened, and 435°C chloride salt enters the packed bed from the fourth collector and diverter 14 at the bottom inlet, and exchanges heat with the Al (66wt%)-Mg (34wt%) alloy phase change medium wrapped in graphite. High-temperature chloride salt is drawn out from the third collector and diverter 13. When the temperature of the chloride salt at the outlet of the third collector and diverter 13 is lower than 660°C, valve 103 is closed, valve 102 is opened, and low-temperature chloride salt is drawn out from the second collector and diverter 12. When the temperature of the chlorine salt at the outlet of the second collector and diverter 12 drops to 660°C, valves 102 and 106 are closed, valve 101 is opened, and the low-temperature chlorine salt is led out from the first collector and diverter 11. At this time, the high-temperature chlorine salt exchanges heat with the single metal aluminum at the top. When the outlet temperature of the first collector and diverter 11 drops to 660°C, the heat release state ends.

[0041] Example 2

[0042] Binary nitrate (60wt% KNO 3 -40wt%NaNO 3 ) is the heat transfer medium, the operating temperature is 290℃~565℃. The end of the heat storage state is marked by the outlet temperature of the fourth collector and splitter 14 at the bottom rising to more than 345℃. The end of the heat release state is marked by the outlet temperature of the first collector and splitter 11 at the top falling to more than 530℃.

[0043] Al (64.3wt%) -Cu (34.0wt%) -Sb (1.7wt%) is selected as a high-temperature phase change material with a phase change point of 545°C, and is placed between the first current collector and diverter 11 and the second current collector and diverter 12. Sand and gravel with a porosity of 42% are filled between the second current collector and diverter 12 and the fourth current collector and diverter 14, randomly stacked, and the equivalent diameter is 2cm. The aluminum alloy phase change material on the top is stacked on the sand and gravel in a long cylindrical shape.

[0044] When storing heat, see Figure 1 , valves 106, 112, and 114 are always closed, valves 101, 111, and 113 are always open, and valves 102, 103, 104, and 105 are opened and closed in sequence according to the temperature of the nitrate drawn out from the collectors and diverters 12, 13, and 14. Specifically, 565°C nitrate enters the packed bed from the first collector and diverter 11 at the top inlet and exchanges heat with the metal aluminum phase change medium wrapped in graphite. Low-temperature nitrate is drawn out from the second collector and diverter 12. When the temperature of the nitrate at the outlet of the second collector and diverter 12 exceeds 345°C, valve 102 is closed, valve 103 is opened, and low-temperature nitrate is drawn out from the third collector and diverter 13. When the temperature of the nitrate at the outlet of the third collector and diverter 13 exceeds 345°C, valves 103 and 105 are closed, valve 104 is opened, and low-temperature nitrate is drawn out from the fourth collector and diverter 14. At this time, the high-temperature nitrate exchanges heat with the sand and gravel at the bottom. When the outlet temperature of the fourth current collector and splitter 14 exceeds 345° C., the heat storage state ends.

[0045] When releasing heat, see Figure 2, valves 104, 112, and 114 are always open. Valves 105, 111, and 113 are always closed. Valves 101, 102, 103, and 106 are opened and closed in sequence according to the temperature of nitrates drawn out from the collectors and diverters 13, 12, and 11. Specifically, at the beginning, valves 103 and 106 are opened, and 290°C nitrates enter the packed bed from the fourth collector and diverter 14 at the bottom inlet, and begin heat exchange with the packed bed of basalt medium. High-temperature nitrates are drawn out from the third collector and diverter 13. When the temperature of the outlet nitrate of the third collector and diverter 13 is lower than 530°C, valve 103 is closed, valve 102 is opened, and low-temperature nitrates are drawn out from the second collector and diverter 12. When the temperature of the outlet nitrate of the second collector and diverter 12 drops to 530°C, valves 102 and 106 are closed, valve 101 is opened, and nitrates are drawn out from the first collector and diverter 11. At this time, the high temperature nitrate exchanges heat with the aluminum alloy (Al (64.3wt%) -Cu (34.0wt%) -Sb (1.7wt%)) phase change medium at the top. When the outlet temperature of the first collector and splitter 11 drops to 530°C, the heat release state ends.

[0046] Application Example 1

[0047] The solid packed bed of the single tank thermocline energy storage device of the prior art includes a sensible hot rock medium located between two current collectors and flow dividers, and has only a single outlet. Nitrate at 565 degrees Celsius enters from the top inlet, and as time goes on, the solid packed bed gradually heats up. Figure 6 As shown, the slope of the thermocline curve gradually increases, which means that the thickness of the thermocline gradually increases. After 5.82 hours, the outlet temperature exceeds the threshold of 345 degrees Celsius, and the heat storage ends.

[0048] The solid packed bed of the single-tank thermocline energy storage device according to the application example of the present invention comprises six collectors and diverters, with sensible hot rock media between adjacent collectors and diverters, and five outlets. Nitrate at 565 degrees Celsius enters from the first diverter collector at the top and flows out from the first outlet of the second diverter collector, such as Figure 7 As shown; when the temperature of the first outlet rises to 345°C, the valve of the second flow divider and collector is closed, and the flow flows out from the second outlet of the third flow divider and collector, as shown Figure 8 As shown; when the temperature of the second outlet rises to 345°C, the valve of the third flow divider and collector is closed, and the flow flows out from the third outlet of the fourth flow divider and collector, as shown Fig. 9 As shown; when the temperature of the third outlet rises to 345°C, the valve of the fourth flow divider and collector is closed, and the flow flows out from the fourth outlet of the fifth flow divider and collector, as shown Fig.10 When the temperature of the fourth outlet rises to 345°C, the valve of the fifth flow divider and collector is closed, and the flow flows out from the fifth outlet of the sixth flow divider and collector, as shown in FIG. Fig.11In this process, the thickness of the thermocline layer will discharge the molten salt thermocline layer of 290℃~345℃ from the tank before each valve is closed, so the thickness of the thermocline layer can be reduced as much as possible, thereby maintaining the stability of the last outlet temperature. Figure 7-Figure 11 It can be seen that after 10.14 hours, the temperature of the fifth outlet exceeds 345°C, which is 1.74 times the thermocline time of a single outlet (5.82 hours). Obviously, the multiple outlet design of the present invention can significantly prolong the stabilization time of the outlet molten salt temperature and effectively control the thickness of the thermocline layer.

[0049] The above is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. The above embodiment of the present invention can also be modified in various ways. That is, all simple, equivalent changes and modifications made according to the claims and the description of the present invention fall within the scope of protection of the claims of the present invention. The contents not described in detail in the present invention are all conventional technical contents.

Claims

1. A single-tank thermocline energy storage device, characterized in that: The single-tank thermocline energy storage device includes a solid packed bed, which includes at least three axially distributed collectors and diverters and a metal phase change material located between the collectors and diverters, wherein the metal phase change material is a graphite-wrapped metal, and the metal is aluminum or an aluminum alloy; during the heat storage process, the molten salt flows in from the top, transfers heat to the metal phase change material layer by layer downwards, and then is drawn out from the collectors and diverters; during the heat release process, the molten salt flows in from the bottom, transfers heat to the molten salt layer by layer upwards, and then is drawn out from the collectors and diverters.

2. The single-tank thermocline energy storage device according to claim 1 is characterized in that: The solid packed bed includes a first metal phase change material and a second metal phase change material. The first metal phase change material is located above the second metal phase change material. The phase change temperature of the first metal phase change material is higher than the phase change temperature of the second metal phase change material.

3. The single-tank thermocline energy storage device according to claim 1 is characterized in that: The solid packed bed also includes a non-metallic phase change material.

4. The single-tank thermocline energy storage device according to claim 3 is characterized in that: Different metal phase change materials or non-metal phase change materials are separated by current collectors and dividers.

5. The single-tank thermocline energy storage device according to claim 1, characterized in that: The current collector and splitter are concentric ring structures.

6. The single-tank thermocline energy storage device according to claim 5, characterized in that: The connector of the current collector and splitter is close to the center of the concentric rings.

7. The single-tank thermocline energy storage device according to claim 1, characterized in that: The metal phase change material is in the shape of a sphere or a cylinder.

8. The single-tank thermocline energy storage device according to claim 1, characterized in that: The single-tank thermocline energy storage device also includes a heat source heat exchanger, a cold source heat exchanger and a molten salt pump, wherein the solid packed bed, the molten salt pump and the heat source heat exchanger are sequentially connected in series to form a cycle during the heat storage process, and the solid packed bed, the heat source heat exchanger, the cold source heat exchanger and the molten salt pump are sequentially connected in series to form a cycle during the heat release process.

9. The single-tank thermocline energy storage device according to claim 8, characterized in that: The solid packed bed, the first valve, the molten salt pump, the second valve, the heat source heat exchanger and the third valve are connected in series in sequence to form a cycle during the heat storage process, and the solid packed bed, the heat source heat exchanger, the fourth valve, the cold source heat exchanger, the molten salt pump, the fifth valve and the sixth valve are connected in series in sequence to form a cycle during the heat release process.

10. The single-tank thermocline energy storage device according to claim 9, characterized in that: The heat source heat exchanger is arranged on a pipeline directly connected to the solid packed bed and is located on a different pipeline from the second valve.

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