High temperature metal phase change thermal battery and electrical thermal storage system

Abstract

The application belongs to the technical field of heat storage, and particularly relates to a high-temperature metal phase change heat battery and an electric heat storage system. The high-temperature metal phase change heat battery comprises heat storage metal, the heat storage metal is coated with a ceramic body, the outer side of the ceramic body is coated with a metal shell, and the metal shell is uniformly fixed with metal fins. The ceramic body functions as a container to coat the heat storage metal inside, can prevent the corrosion of the heat storage metal on the heater and the heat exchanger, and the metal shell and the metal fins are arranged outside the ceramic body, the metal shell has the functions of mechanical support and hoisting, and the metal fins have the function of enhancing heat exchange. The high-temperature metal phase change heat battery is used in the electric heat storage system, the heat storage system has compact structure, efficient and adjustable heat exchange mode, and effectively solves the problems of low heat storage density, narrow temperature range and poor long-term stability of the traditional electric heat storage system.

Description

Technical Field

[0001] This invention belongs to the field of thermal energy storage technology, specifically relating to a high-temperature metal phase change thermal battery and an electric thermal energy storage system. Background Technology

[0002] With the development of intermittent renewable energy sources such as photovoltaics and wind power, the stability of the power grid has faced significant challenges. Furthermore, the application of peak-valley electricity is gradually attracting attention. Power energy systems require energy storage for peak shaving and stable output. Among various energy storage solutions, thermal energy storage is a promising option due to its low cost and close connection with downstream customers.

[0003] Existing thermal energy storage methods mainly include molten salt thermal energy storage, solid inorganic thermal energy storage, molten salt phase change thermal energy storage, and solid metal thermal energy storage, which have been promoted and applied to a certain extent in the market. Thermal energy storage systems are closely related to the thermal energy storage medium. Existing thermal energy storage still faces many challenges in high-temperature applications. Molten salt thermal energy storage currently mainly uses nitrates, with a temperature upper limit limited to 560 degrees Celsius. Solid metal thermal energy storage suffers from low thermal density. Solid inorganic materials, on the other hand, have problems such as pulverization during long-term use, large volume, and large footprint.

[0004] High-enthalpy latent heat storage based on high-temperature metal phase change can effectively overcome limitations in heat storage density, temperature, and long-term stability by employing large-scale encapsulated thermal storage batteries. However, the main problem with current metal latent heat storage is liquid metal corrosion, where heaters and heat exchangers are in direct contact with the stored metal. Due to the corrosive effect of the liquid metal, both heaters and heat exchangers suffer from severe corrosion. Existing metal thermal storage bodies cannot operate long-term and pose safety hazards. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a high-temperature metal phase change thermal battery and an electric thermal storage system. A ceramic body is wrapped around the thermal storage metal to prevent corrosion of heaters and heat exchangers. A metal shell and metal fins are arranged on the outside of the ceramic body. The metal shell provides mechanical support and slinging, while the metal fins dissipate heat, thus solving the aforementioned problems.

[0006] The present invention is specifically implemented through the following technical solution.

[0007] This invention provides a high-temperature metal phase change thermal battery, comprising a heat storage metal, an outer ceramic body, and a metal shell surrounding the ceramic body. Metal fins are uniformly fixed to the metal shell. The ceramic body acts as a container, enclosing the heat storage metal and preventing corrosion damage caused by the heat storage metal liquefying upon heating. The metal shell provides mechanical support and supports the battery, while the metal fins facilitate heat exchange between the heat storage metal and the surrounding medium.

[0008] In a preferred embodiment of the present invention, the heat storage metal is composed of metallic materials such as aluminum alloy and copper alloy. After absorbing heat, the heat storage metal reaches its phase change temperature and becomes a liquid metal. After releasing heat, the liquid metal reverts to a solid metal, thus achieving heat storage through the aforementioned phase change process.

[0009] In a preferred embodiment of the present invention, the phase change temperature is higher than 550°C, and the operating temperature of the metal phase change thermal battery is 25°C-1000°C.

[0010] In a preferred embodiment of the present invention, the ceramic body is composed of graphite, silicon carbide, silicon nitride or alumina, and has the properties of high temperature resistance, high thermal conductivity, oxidation resistance and liquid metal corrosion resistance.

[0011] In a preferred embodiment of the present invention, the metal fins or metal shell are composed of heat-resistant and oxidation-resistant metal materials, including heat-resistant metals or high-temperature alloys such as stainless steel 201, 301, 304, or 306. The metal shell provides mechanical support and supports the hoisting, while the metal fins dissipate heat.

[0012] In a preferred embodiment of the present invention, the outer diameter of the metal shell is 150mm-1600mm, the height of the metal shell is 200mm-5000mm, and the thickness of the ceramic body is 5mm-60mm.

[0013] The present invention also provides an electric thermal storage system, including a steel outer shell, a cavity formed inside the steel outer shell, a plurality of the aforementioned thermal batteries disposed inside the cavity, an insulation layer disposed on the inner side of the steel outer shell, and an electric heating component disposed within the insulation layer, the electric heating component being used to perform radiative and convective electric heating on the thermal batteries; and a heat exchange system for exchanging heat with the high-temperature metal phase change thermal battery, using the heat in the battery for user-side use.

[0014] In a preferred embodiment of the present invention, the multiple sets of thermal batteries are arranged in two rows, the number of thermal batteries is determined according to the heat storage capacity, and the spacing is 300mm-600mm.

[0015] In a preferred embodiment of the present invention, the heat exchange system includes a fan and a heat exchanger. The fan delivers cold air into the accommodating cavity to exchange heat with the thermal battery. The hot air, after heat exchange, enters the heat exchanger from the accommodating cavity, heating the medium in the heat exchanger. The cold air is discharged from the heat exchanger and re-enters the accommodating cavity via the fan. The hot air transfers heat to a load, which may be hot air, hot water, hot oil, or hot steam, through the heat exchanger.

[0016] In a preferred embodiment of the present invention, the sidewall of the accommodating cavity is provided with an inlet and an outlet. The inlet is connected to the fan, which sends cold air into the accommodating cavity through the inlet. A temperature sensor A is installed inside the accommodating cavity, and a control valve A is installed at the outlet. The temperature sensor A and the control valve A are electrically connected to a controller A. The temperature sensor A is used to detect the temperature of the air inside the accommodating cavity and send the temperature signal to the controller A. When the temperature reaches a preset temperature, the controller A controls the control valve A to open, allowing the hot air inside the accommodating cavity to enter the heat exchanger. The hot air heats the medium in the heat exchanger, and the cold air is discharged from the heat exchanger and re-enters the accommodating cavity through the fan.

[0017] In a preferred embodiment of the present invention, a flow sensor A is further installed at the inlet of the accommodating cavity to detect the flow rate of cold air entering the accommodating cavity, and the flow sensor A is electrically connected to the controller A.

[0018] In a preferred embodiment of the present invention, the heat exchange system does not require a heat exchanger; the medium directly exchanges heat with the thermal battery, and the heated medium is used directly. The heat exchanger system includes a booster and a pipe wound around the thermal battery. A control valve B is installed at the outlet of the pipe, and a temperature sensor B is installed inside the pipe. The control valve B and the temperature sensor B are electrically connected to a controller B. The booster introduces carbon dioxide, cold air, water, or oil into the pipe for direct heating. The temperature sensor B is used to detect the temperature of the medium inside the pipe and sends a signal to the controller B. When the temperature reaches a preset temperature, the controller B controls the control valve B to open, and the heated medium is directly used to drive the steam turbine to generate electricity.

[0019] In a preferred embodiment of the present invention, a medium input guide pipe and a medium output guide pipe are provided in the accommodating cavity. A pipe is wound around each of the plurality of thermal batteries. The inlet of each pipe is connected to the medium input guide pipe, and the outlet of each pipe is connected to the medium output guide pipe. A flow sensor B and a flow sensor C are respectively installed on the medium input guide pipe and the medium output guide pipe. The flow sensor B and the flow sensor C are electrically connected to the controller B.

[0020] In a preferred embodiment of the present invention, the insulation layer includes an inner magnesium oxide refractory layer, a ceramic fiber intermediate layer, and a refractory outer layer. The refractory outer layer is made of alumina-silica refractory material, and the electric heating component is distributed within the magnesium oxide refractory layer.

[0021] Compared with the prior art, the present invention has the following advantages:

[0022] This invention proposes a novel high-temperature metal phase change thermal battery. A ceramic body acts as a container, encasing the stored metal within it, preventing corrosion of the heater and heat exchanger. A metal shell and metal fins are arranged on the outside of the ceramic body. The metal shell provides mechanical support and lifting, while the metal fins dissipate heat. Applying this high-temperature metal phase change thermal battery to an electric thermal storage system effectively solves problems related to heat storage density, temperature, and long-term stability. During system operation, the charging process stores heat in the thermal battery through electric heating, while the dissipation process releases heat for user use through heat exchange between the battery surface and the air or a medium in a pipe. Throughout the entire operation, the metal inside the thermal battery remains state-of-the-art during charging and dissipation, and the heat-resistant steel shell ensures the long-term stability of the system, avoiding the weathering and aging problems of traditional solid-state thermal storage. Attached Figure Description

[0023] Figure 1 This is a schematic diagram of the high-temperature metal phase change thermal battery structure provided by the present invention;

[0024] Figure 2 This is a top view of a high-temperature metal phase change thermal battery;

[0025] Figure 3 This is a 3D diagram of a high-temperature metal phase change thermal battery;

[0026] Figure 4 This is a diagram of an electric thermal storage system based on a high-temperature metal phase change thermal battery;

[0027] Figure 5 This is a diagram of another type of electric thermal storage system based on a high-temperature metal phase change thermal battery;

[0028] Figure 6 yes Figure 5 A schematic diagram of the structure of a high-temperature metal phase change thermal battery with a pipe wrapped around its outer side.

[0029] Figure 7 yes Figure 6 A sectional view;

[0030] Explanation of reference numerals in the attached figures:

[0031] 1. Metal fins, 2. Metal shell, 3. Ceramic body, 4. Heat storage metal, 5. Steel shell, 51. Receptacle, 511. Receptacle inlet, 512. Receptacle outlet, 513. Medium input guide pipe, 514. Medium output guide pipe, 52. Insulation layer, 53. Fan, 54. Heat exchanger, 6. Thermal cell, 61. Pipeline, 7. Booster. Detailed Implementation

[0032] To enable those skilled in the art to better understand and implement the technical solutions of the present invention, the present invention will be further described below in conjunction with specific embodiments and accompanying drawings. However, the embodiments described are not intended to limit the present invention.

[0033] Unless otherwise specified, the experimental and detection methods described in the following embodiments are conventional methods; unless otherwise specified, the reagents and materials are commercially available.

[0034] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0035] The greenhouse effect and energy crisis have led to the rapid development of new energy sources, posing a significant challenge to the stability of the power grid. To address this issue, during off-peak hours, the grid stores electrical energy, and during peak hours, it releases the stored energy for utilization. Therefore, energy storage is crucial. Among various energy storage solutions, thermal storage holds significant application potential. The thermal storage medium is key to the thermal storage system. Current thermal storage media include molten salt, solid inorganic materials, solid metals, and molten salt phase change thermal storage. Molten salt thermal storage currently primarily uses nitrates, with a temperature limit of 560 degrees Celsius. Solid metal thermal storage suffers from low thermal density. Solid inorganic materials, on the other hand, suffer from problems such as pulverization during long-term use, large volume, and large footprint. High-temperature metal phase change thermal storage with high enthalpy latent heat offers advantages such as high thermal density, high temperature, and high long-term stability. After absorbing heat, the metal reaches the phase change temperature, becoming a liquid metal. After releasing heat, the liquid metal returns to a solid metal, thus achieving heat storage through this phase change process. However, currently, liquid metal is in direct contact with heaters or heat exchangers, which makes it prone to corrosion damage.

[0036] To address the above problems, this invention provides a high-temperature metal phase change thermal battery, such as... Figures 1-3As shown, the device includes a heat storage metal 4, which stores heat through a high-temperature phase change. The heat storage metal 4 is covered by a ceramic body 3, which is a corrosion-resistant material to prevent corrosion of the heater or heat exchanger by the liquid metal. A metal shell 2 covers the outside of the ceramic body 3, providing mechanical support. Metal fins 1 are uniformly fixed to the metal shell 2 for heat dissipation and heat exchange with the medium. The phase change temperature of the heat storage metal 4 is higher than 550℃, and the operating temperature of the metal phase change thermal battery is 25-1000℃. The ceramic body 3 is made of graphite, silicon carbide, silicon nitride, or alumina, and possesses high temperature resistance, high thermal conductivity, oxidation resistance, and resistance to liquid metal corrosion. The metal fins 1 or the metal shell 2 are composed of heat-resistant and oxidation-resistant metal materials, including stainless steel 201, 301, 304, or 306. The metal shell provides mechanical support, while the metal fins dissipate heat.

[0037] In one preferred embodiment, the heat storage metal 4 is made of aluminum alloy or copper alloy.

[0038] When aluminum alloy is used as the heat storage medium, the metal phase transition temperature is 580℃. Silicon carbide is used as the ceramic material, and 304L stainless steel is used for the shell and fins. The outer diameter of the thermal storage battery is 800mm, and the height is 1500mm. The operating temperature is 25℃-800℃.

[0039] When copper alloy is used as the heat storage medium, the metal phase transition temperature is 820℃. The ceramic material is graphite silicon carbide, and the shell and fins are made of 316L stainless steel. The outer diameter of the thermal storage battery is 800mm, and the height is 1500mm. The operating temperature is 25℃-1000℃.

[0040] The present invention also provides an electric thermal storage system, such as Figure 4 As shown, it includes a steel outer shell 5, with a receiving cavity 51 inside the steel outer shell 5. Multiple sets of the aforementioned thermal batteries 6 are disposed inside the receiving cavity 51. An insulation layer 52 is disposed inside the steel outer shell 5, and an electric heating component is disposed inside the insulation layer 52. The electric heating component is used to perform radiative and convective electric heating on the thermal batteries 6 and store the heat in the heat storage metal 4. It also includes a heat exchange system for exchanging heat with the thermal batteries 6. The heat in the heat storage metal 4 is released and transported to the user end for use through the heat exchange system.

[0041] In a preferred embodiment of the present invention, such as Figure 4As shown, the heat exchange system includes a fan 53 and a heat exchanger 54. The fan 53 sends cold air into the accommodating cavity 51 to exchange heat with the thermal battery 6. The hot air after heat exchange enters the heat exchanger 54 from the accommodating cavity 51, heating the medium in the heat exchanger 54 and transferring the heat to the load, which can be hot air, hot water, hot oil, or hot steam. The cold air is discharged from the heat exchanger 54 and re-enters the accommodating cavity 51 through the fan 53 to exchange heat with the thermal battery 6 again.

[0042] The above process describes how the thermal battery 6 releases and utilizes the stored heat. To improve the controllability of this process, a system control is implemented. In a preferred embodiment of the present invention, the sidewall of the accommodating cavity 51 is provided with an accommodating cavity inlet 511 and an accommodating cavity outlet 512. The accommodating cavity inlet 511 is connected to the fan 53. The fan 53 sends cold air into the accommodating cavity 51 through the accommodating cavity inlet 511 to exchange heat with the thermal battery 6. The metal fins 1 facilitate heat dissipation of the thermal battery. A temperature sensor A is installed inside the accommodating cavity 51, and a control valve A is installed on the accommodating cavity outlet 512. The temperature sensor A and the control valve A are electrically connected to the controller A. The temperature sensor A is used to detect the temperature of the air inside the accommodating cavity 51 and send the temperature signal to the controller A. When the temperature reaches the preset temperature, the controller A controls the control valve A to open, allowing the hot air inside the accommodating cavity 51 to enter the heat exchanger 54 for heat exchange, thus improving the controllability of the temperature. A flow sensor A is also installed at the inlet 511 of the accommodating cavity to detect the flow rate of cold air entering the accommodating cavity 51. The flow sensor A is electrically connected to the controller A. According to user needs, the monitoring flow rate of the flow sensor A can be set, improving the controllability of the air flow process. The specific structures of the temperature sensor A, control valve A, controller A, and flow sensor A used are not limited, and any existing technology can be used as long as it can achieve the above-mentioned control process.

[0043] In the above process, after the thermal battery 6 releases heat, a heat exchanger 54 is needed to deliver the heat to the user. In another heat exchange method of the present invention, a heat exchanger is not required, and the heat released by the thermal battery 6 can be directly utilized, which simplifies the thermal storage system process and reduces the installation and operation costs of the device.

[0044] like Figures 5-7In a preferred embodiment of the present invention, the heat exchange system includes a booster 7 and a pipe 61 wound around the thermal battery 6. A control valve B is installed at the outlet of the pipe 61, and a temperature sensor B is disposed inside the pipe 61. The control valve B and the temperature sensor B are electrically connected to a controller B. The booster 7 introduces carbon dioxide, cold air, water, or oil into the pipe 61 for heat exchange with the thermal battery 6. The metal fins 1 facilitate heat dissipation from the thermal battery 6. The temperature sensor B detects the temperature of the medium inside the pipe 61 and sends a signal to the controller B. When the temperature reaches a preset temperature, the controller B controls the control valve B to open, and the heated medium is directly used to drive the turbine for power generation. This heat exchange method eliminates the need for an additional heat exchanger, allowing the heat released from the thermal battery 6 to be delivered to the user end.

[0045] To ensure controllability of the process of carbon dioxide, cold air, water, or oil entering pipe 61, a medium input guide pipe 513 and a medium output guide pipe 514 are provided within the accommodating cavity 51. Each thermal battery 6 is wound with a pipe 61. The inlet of each pipe 61 is connected to the medium input guide pipe 513, and the outlet of each pipe 61 is connected to the medium output guide pipe 514. Carbon dioxide, cold air, water, or oil enters pipe 61 through the medium input guide pipe 513. Flow sensors B and C are respectively installed on the medium input guide pipe 513 and the medium output guide pipe 514. Flow sensors B and C are electrically connected to the controller B to control the flow rate of the medium entering and exiting, thus achieving controllable operation. The specific structures of the temperature sensor B, control valve B, controller B, flow sensor B, and flow sensor C used are not limited; any existing technology can be used, as long as it can achieve the above-mentioned control process.

[0046] Based on the above description, the system of the present invention can be specifically implemented in the following applications:

[0047] 1) Store the electrical energy generated by wind power in a thermal storage system to stably provide hot water and hot air for application.

[0048] 2) Store the electrical energy generated by photovoltaic power generation in a thermal storage system to stably provide hot water and hot air for application.

[0049] 3) Store off-peak electricity from the power grid into the thermal storage system to stably provide hot water and hot air for use.

[0050] 4) Store off-peak electricity from the power grid into a thermal storage system to provide hot steam for generator sets.

[0051] 5) Store off-peak electricity from the power grid into a thermal storage system to provide ultra-supercritical carbon dioxide for generator sets.

[0052] And similar related applications.

[0053] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. Therefore, it is intended to include any modifications and variations that fall within the scope of the claims and their equivalents.

Claims

1. A high-temperature metal phase change thermal battery, characterized in that, It includes a heat storage metal (4), the heat storage metal (4) is covered with a ceramic body (3), the ceramic body (3) is covered with a metal shell (2), and metal fins (1) are uniformly fixed on the metal shell (2).

2. The high-temperature metal phase change thermal battery according to claim 1, characterized in that, The heat storage metal (4) is made of aluminum alloy or copper alloy.

3. The high-temperature metal phase change thermal battery according to claim 1, characterized in that, The phase change temperature of the heat storage metal (4) is higher than 550°C, and the operating temperature of the metal phase change thermal battery is 25-1000°C.

4. The high-temperature metal phase change thermal battery according to claim 1, characterized in that, The ceramic body (3) is a graphite, silicon carbide, silicon nitride or alumina refractory material.

5. An electric thermal energy storage system, characterized in that, The device includes a steel outer shell (5), which has a cavity (51) inside. The cavity (51) is equipped with multiple sets of thermal batteries (6) as described in claim 1. The inner side of the steel outer shell (5) is equipped with a heat insulation layer (52), and the heat insulation layer (52) is equipped with an electric heating component. The electric heating component is used to perform radiative and convective electric heating on the thermal batteries (6) and store the heat in the heat storage metal (4). The device also includes a heat exchange system for exchanging heat with the thermal batteries (6).

6. The electric thermal energy storage system according to claim 5, characterized in that, The heat exchange system includes a fan (53) and a heat exchanger (54). The fan (53) sends cold air into the cavity (51) to exchange heat with the thermal battery (6). The hot air after heat exchange enters the heat exchanger (54) from the cavity (51) and heats the medium in the heat exchanger (54). The cold air is discharged from the heat exchanger (54) and re-enters the cavity (51) through the fan (53).

7. The electric thermal energy storage system according to claim 6, characterized in that, The sidewall of the accommodating cavity (51) is provided with an inlet (511) and an outlet (512). The inlet (511) is connected to the fan (53). The fan (53) sends cold air into the accommodating cavity (51) through the inlet (511). A temperature sensor A is installed in the accommodating cavity (51), and a control valve A is installed on the outlet (512). The temperature sensor A and the control valve A are electrically connected to the controller A. The temperature sensor A is used to detect the temperature of the air in the accommodating cavity (51) and send the temperature signal to the controller A. When the temperature reaches the preset temperature, the controller A controls the control valve A to open, so that the hot air in the accommodating cavity (51) enters the heat exchanger (54).

8. The electric thermal energy storage system according to claim 7, characterized in that, The inlet (511) of the accommodating cavity is also equipped with a flow sensor A, which is used to detect the flow rate of cold air entering the accommodating cavity (51). The flow sensor A is electrically connected to the controller A.

9. The electric thermal energy storage system according to claim 5, characterized in that, The heat exchange system includes a booster (7) and a pipe (61) wound around the thermal battery (6). A control valve B is installed at the outlet of the pipe (61), and a temperature sensor B is installed inside the pipe (61). The control valve B and the temperature sensor B are electrically connected to the controller B. The booster (7) introduces carbon dioxide, cold air, water or oil into the pipe (61) to exchange heat with the thermal battery (6). The temperature sensor B is used to detect the temperature of the medium inside the pipe (61) and sends the signal to the controller B. When the temperature reaches the preset temperature, the controller B controls the control valve B to open, and the heated medium inside the pipe (61) is directly used to drive the steam turbine to generate electricity.

10. The electric thermal energy storage system according to claim 9, characterized in that, The accommodating cavity (51) is provided with a medium input guide pipe (513) and a medium output guide pipe (514). Each thermal battery (6) is wound with a pipe (61). The inlet of each pipe (61) is connected to the medium input guide pipe (513), and the outlet of each pipe (61) is connected to the medium output guide pipe (514). Flow sensor B and flow sensor C are respectively installed on the medium input guide pipe (513) and the medium output guide pipe (514). The flow sensor B and flow sensor C are electrically connected to the controller B.

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