Carnot battery energy storage system
By using multi-stage thermal storage modules and flexible power output control, the problems of low energy utilization and poor output adjustability in the Carnot battery system are solved, achieving efficient and stable heat storage and utilization.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- STATE GRID SHANGHAI MUNICIPAL ELECTRIC POWER CO
- Filing Date
- 2026-04-02
- Publication Date
- 2026-05-12
AI Technical Summary
Existing Carnot battery systems suffer from low energy utilization, poor output adjustability, slow thermal response, and difficulty in balancing heating efficiency and stability.
It adopts a multi-stage thermal storage module structure, and through series-connected heat storage and heat release circulation pipelines, combined with solid-liquid phase change materials and liquid-gas phase change materials, it realizes cascade heating and flexible power output control.
It improves energy utilization, enhances output adjustability, increases heat storage response speed and heating efficiency, and improves system stability and flexibility.
Smart Images
Figure CN122014370A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of large-scale energy storage technology, and more specifically to a Carnot battery energy storage system. Background Technology
[0002] Carnot batteries refer to a type of large-scale electrical energy storage system based on thermal energy storage. Carnot batteries convert electrical energy into thermal energy and store this thermal energy in a heat storage medium, such as molten salt phase change materials. When electrical energy is needed, the thermal energy is converted back into electrical energy through specific equipment for reuse. With the increasing penetration rate of renewable energy, large-scale, long-term energy storage technologies have become crucial for the stable operation of the power grid. As a large-scale physical energy storage technology based on thermodynamic cycles, Carnot batteries have attracted widespread attention due to their large energy storage capacity, long lifespan, and cost potential.
[0003] Existing Carnot battery systems typically employ single- or dual-tank molten salt sensible heat storage technology, but they still suffer from drawbacks such as slow heat storage response, low energy utilization, significant waste, poor output adjustability, and difficulty in balancing heating efficiency and stability. Summary of the Invention
[0004] In view of the shortcomings of the prior art, the technical problem to be solved by the present invention is: how to provide a Carnot battery energy storage system with high energy utilization, better output adjustability, fast heat storage response, high heating efficiency and good stability.
[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A Carnot battery energy storage system includes an electric heater, a heat storage device, a turbine expander, and a generator. A heat storage circulation pipeline is connected between the electric heater and the heat storage device. A heat storage circulation pump is installed on the heat storage circulation pipeline, and a heat storage fluid medium is disposed within the pipeline. A heat release circulation pipeline is also connected between the heat storage device and the turbine expander. A heat release circulation pump is installed on the heat release circulation pipeline, and a heat release fluid medium is disposed within the pipeline. The power output end of the turbine expander is connected to the input end of the generator. The heat storage device comprises a first heat storage module and a second heat storage module. The first, second, and third heat storage modules each contain a heat storage pipeline, a heat release pipeline, and a heat storage chamber containing solid-liquid phase change material. The phase change temperatures of the solid-liquid phase change material in the first, second, and third heat storage modules decrease sequentially. The heat storage pipelines of the first, second, and third heat storage modules are connected in series in the heat storage circulation pipeline and in series with the electric heater. The heat release pipelines of the third, second, and first heat storage modules are connected in series in the heat release circulation pipeline and in series with the turbine expander.
[0006] In this way, during charging and energy storage, the electric heater generates heat, which is then transferred sequentially through the first, second, and third heat storage modules by the heat storage fluid medium in the heat storage circulation pipeline, heating the solid-liquid phase change material within each module. After heat exchange in the first heat storage module, the heat storage fluid medium, with a slightly lower temperature, is then heated again by the second heat storage module, which has a lower phase change temperature. After another slight decrease in temperature, it is heated again by the third heat storage module, which has an even lower phase change temperature. Therefore, heat waste is effectively avoided during the heat storage process. Then, during heat release and power generation, the heat release fluid medium in the heat release circulation pipeline gradually preheats from low to medium to high temperatures by passing through the third, second, and first heat storage modules, ultimately reaching a higher temperature to heat the turbine expander and improve the final heating effect. Therefore, this multi-stage heat storage module system in the heat storage and power generation process achieves tiered heating utilization, better avoiding waste and improving energy utilization efficiency.
[0007] Furthermore, the thermal storage device has an overall rectangular structure, with the first, second, and third thermal storage modules stacked sequentially from top to bottom. This structure is simple, compact, easy to implement, and better avoids heat loss from the thermal storage modules.
[0008] Furthermore, in each heat storage module, the heat storage pipeline is located on the lower side of the heat storage chamber, and the heat release pipeline is located on the upper side of the heat storage chamber; both the heat storage pipeline and the heat release pipeline have a tortuous wavy shape on the side adjacent to the heat storage chamber.
[0009] This allows for more convenient heat storage and release, and improves the efficiency of heat storage and release.
[0010] Furthermore, the solid-liquid phase change material is an inorganic salt mixture phase change material. This has advantages such as low cost, ease of implementation, and convenient adjustment of the phase change temperature.
[0011] Furthermore, the phase transition temperatures of the solid-liquid phase change materials in the first, second, and third thermal storage modules are 700℃, 600℃, and 500℃, respectively. This temperature gradient interval is moderate, which is beneficial for achieving proportional and synchronous temperature rise and energy storage during sequential heating.
[0012] Furthermore, in each heat storage module, a heat transfer interlayer chamber is also provided on the side adjacent to the heat storage pipeline channel and the heat storage chamber. The heat transfer interlayer chamber is provided with a heat transfer fluid medium. One end of the heat transfer interlayer chamber is connected to a heat transfer pipe. The heat transfer pipe is connected into the heat storage chamber to form a heat transfer network and is connected back to the heat transfer interlayer chamber to form a circulation. A heat transfer circulation pump is provided on the heat transfer pipe.
[0013] In this way, when the heat storage fluid flows through the heat storage pipeline channels of the heat storage module, it first heats the heat transfer jacket chamber, causing the temperature of the heat transfer fluid medium inside to rise rapidly. Then, under the action of the heat transfer circulation pump, the high-temperature heat transfer fluid medium exchanges heat with the solid-liquid phase change material through the heat transfer pipeline network and returns to the heat transfer jacket chamber for reheating, thus forming a circulation and rapidly transferring heat into the heat storage chamber. Therefore, the heat storage efficiency in the heat storage module is greatly improved.
[0014] Furthermore, the heat transfer network includes a main heat transfer pipe horizontally arranged on the side away from the heat storage pipeline channel, and several branch heat transfer pipes connected in a vertical direction are evenly distributed on the main heat transfer pipe. The branch heat transfer pipes are arranged in a tortuous manner and connected back to the heat transfer jacket chamber.
[0015] This allows for more uniform heating of the solid-liquid phase change material inside the heat storage chamber, avoiding excessive local heating and better ensuring the stability of the device.
[0016] Furthermore, the heat transfer pipe and the heat transfer circulation pump thereon are located outside the heat storage chamber.
[0017] This makes it easier to inspect, maintain, and control the heat transfer circulation pump.
[0018] Furthermore, a layer of porous thermally conductive material is also provided on the inner wall of the side adjacent to the heat transfer jacket chamber and the heat storage pipeline channel. This greatly improves the heat exchange efficiency of the heat storage pipeline channel to the heat transfer jacket chamber.
[0019] In practice, the porous thermal conductive material is preferably a sintered porous metal material with an average porosity of 50%-85% and a pore size of 10-200 micrometers, so as to better ensure the heat exchange effect.
[0020] Furthermore, the heat transfer fluid medium is a liquid-gas phase change material, and the phase change temperature of the liquid-gas phase change material is greater than the phase change temperature of the solid-liquid phase change material in the heat storage module.
[0021] In this way, the liquid-gas phase change material is normally adsorbed within the porous thermally conductive material. When the heat storage fluid flows through the heat storage pipeline to heat the heat transfer jacket chamber, the liquid-gas phase change material rapidly vaporizes under the action of the porous thermally conductive material, forming a high-temperature heat transfer gas. Then, under the action of the heat transfer circulation pump, the high-temperature heat transfer gas exchanges heat with the solid-liquid phase change material through the heat transfer pipeline network and returns to the heat transfer jacket chamber, thus forming a cycle and achieving rapid and stable heat storage. During this process, because the heat transfer fluid medium is a liquid-gas phase change material, the upper limit of the heating temperature of the solid-liquid phase change material is limited, thus greatly improving the stability of the heating process while ensuring high heating efficiency. In practice, under unheated conditions, the amount of liquid-gas phase change material is limited to that adsorbed within the porous thermally conductive material. This avoids excessive liquid-gas phase change material causing excessive thermal expansion and affecting the stability of the device.
[0022] Furthermore, the phase change temperature of the liquid-gas phase change material is 5-50°C higher than that of the solid-liquid phase change material in the thermal storage module.
[0023] This is because the phase change temperatures of the solid-liquid phase change materials in the first, second, and third thermal storage modules are 700℃, 600℃, and 500℃, respectively, resulting in significant temperature differences. To heat the first thermal storage module, the electric heater's operating temperature would exceed 700℃. Therefore, when the electric heater needs to supplement heat to the second or third thermal storage module separately, the input temperature of the heat storage fluid medium would far exceed the phase change temperature of the solid-liquid phase change material within the module. This could easily lead to excessively rapid localized heating within the thermal storage module, even vaporization and expansion, significantly reducing the module's stability and lifespan. Therefore, using a liquid-gas phase change material as the heat transfer fluid medium, with a phase change temperature only 5-50℃ higher than the solid-liquid phase change material's phase change temperature, avoids the defects caused by excessively rapid localized heating within the thermal storage module. This better ensures high heat exchange efficiency while improving the device's stability and extending the module's lifespan.
[0024] In practice, the liquid-gas phase change material is preferably a liquid metal, specifically a mixture of sodium, potassium, or a sodium-potassium eutectic alloy. This results in low cost, easy adjustment of the vaporization temperature, and high heat exchange efficiency.
[0025] Furthermore, the turbine expander has one output port and three return ports. A heat release circulation pump is installed on the heat release circulation pipeline from the output port of the turbine expander and connected to a third heat storage module. The heat release circulation pipeline from the third heat storage module is connected to a second heat storage module, and a third heat release return branch is also connected to this pipeline. A third heat release return branch switch valve is installed on the third heat release return branch and connected to one return port of the turbine expander. A second heat release switch valve is also installed on the heat release circulation pipeline between the third heat release return branch and the second heat storage module. The heat release circulation pipeline from the second heat storage module is connected to the first heat storage module, and a second heat release return branch is also connected to this pipeline. A second heat release return branch switch valve is installed on the second heat release return branch and connected to another return port of the turbine expander. A first heat release switch valve is also installed on the heat release circulation pipeline between the second heat release return branch and the first heat storage module. The heat release circulation pipeline from the first heat storage module is connected to the third return port of the turbine expander.
[0026] Thus, when the generator's power demand is low, the third heat return branch switch valve can be opened and the second heat return switch valve closed. This ensures that the heat exchange pipeline only passes through the third heat storage module, relying solely on the lowest-temperature third heat storage module to heat and generate electricity for the turbine expander. When the generator's power demand is moderate, the third heat return branch switch valve and the first heat return switch valve can be closed, while the second heat return switch valve and the second heat return branch switch valve can be opened simultaneously. This allows the heat-generating fluid medium to be preheated by the first heat storage module and then heated by the second heat storage module before supplying heat and electricity to the turbine expander, producing a moderate amount of electricity. When the generator's power demand is maximum, the third heat return branch switch valve and the second heat return branch switch valve can be closed, while the second heat return switch valve and the first heat return switch valve can be opened simultaneously. This allows the heat-generating fluid medium to be heated sequentially through the third, second, and first heat storage modules before supplying heat and electricity to the turbine expander, producing the maximum amount of electricity. Therefore, it can achieve different power outputs according to power supply needs, making the equipment more flexible and versatile, and improving its applicability.
[0027] Furthermore, the electric heater has one output port and three return ports. A heat storage circulation pump is installed on the heat storage circulation pipeline connected to the output port of the electric heater and connected to the first heat storage module. A heat storage switch valve for the first heat storage module input end is installed on the heat storage circulation pipeline near the input end of the first heat storage module. A first heat storage bypass branch and a second heat storage bypass branch are also connected to the heat storage circulation pipeline between the heat storage circulation pump and the first heat storage module input end heat storage switch valve. A first heat storage bypass branch heat storage switch valve is installed on the first heat storage bypass branch and connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. A second heat storage bypass branch heat storage switch valve is installed on the second heat storage bypass branch and connected to the heat storage circulation pipeline between the second heat storage module and the third heat storage module. A third heat storage bypass branch heat storage switch valve is also connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. A heat storage reflux branch is connected to a reflux port of the return electric heater. A heat storage switch valve is also installed on the first heat storage reflux branch. A heat storage switch valve for the input end of the second heat storage module is also installed on the heat storage circulation pipeline between the first heat storage reflux branch and the first heat storage bypass branch. A heat storage switch valve for the output end of the second heat storage module and a heat storage switch valve for the input end of the third heat storage module are respectively installed on both sides of the second heat storage bypass branch on the heat storage circulation pipeline between the second heat storage module output end heat storage switch valve and the third heat storage module input end heat storage switch valve. A second heat storage reflux branch is also provided on the heat storage circulation pipeline between the second heat storage module output end heat storage switch valve and the third heat storage module input end heat storage switch valve, and another reflux port of the return electric heater is connected to it. A heat storage switch valve for the second heat storage reflux branch is installed on the second heat storage reflux branch. The heat storage circulation pipeline at the output end of the third heat storage module is connected to the third reflux port of the return electric heater.
[0028] Thus, through the aforementioned piping and control valve structure, seven heating methods can be achieved, including individual heating of the three heat storage modules, heating in pairs, or heating together. Specifically, when heating all three heat storage modules simultaneously, simply close the heat storage switch valves on the two heat storage bypass branches and the two heat storage return branches, and open the remaining heat storage switch valves to achieve series heating of the first, second, and third heat storage modules sequentially. When heating only the first heat storage module, simply open the heat storage switch valve at the input end of the first heat storage module and the heat storage switch valve on the first heat storage return branch, and close the remaining heat storage switch valves to achieve heating of the first heat storage module alone. When heating both the first and second heat storage modules simultaneously, simply open the heat storage switch valves at the input end of the first heat storage module, the input end of the second heat storage module, and the second heat storage return branch, and close the remaining heat storage switch valves to achieve series heating of the first and second heat storage modules individually. When heating both the first and third thermal storage modules simultaneously is required, simply open the thermal storage switch valves at the input, return, and bypass branches of the first and third thermal storage modules, and close the remaining thermal storage switch valves to achieve parallel heating for each module. When heating only the second thermal storage module is required, simply open the thermal storage switch valves at the bypass, output, and return branches of the second and third thermal storage modules, and close the remaining thermal storage switch valves to achieve parallel heating for both modules. When only the third heat storage module needs to be heated, simply open the heat storage switch valve of the second heat storage bypass branch and the heat storage switch valve at the input end of the third heat storage module, and close the other heat storage switch valves to achieve independent heating for the third heat storage module.
[0029] Therefore, the aforementioned piping and control valve structure can achieve heating control of a single module, any two modules, or all modules of the thermal storage system, enabling it to effectively handle situations where heating is required after any thermal storage module releases heat. Furthermore, when two or more thermal storage modules need to be heated simultaneously, except in cases where the first and third thermal storage modules need to be heated simultaneously, series heating from high to low temperature can be achieved, better avoiding energy waste and improving energy storage and utilization efficiency during the heating process.
[0030] Furthermore, each of the first, second, and third heat storage modules has a thermometer installed in its heat storage chamber and connected to the control center. The control center is also connected to each heat storage switch valve and each heat release switch valve.
[0031] This allows for better detection of the internal heat storage status of each heat storage module, enabling the assessment and control of the heat storage charging and heat release power generation processes.
[0032] Furthermore, thermometers connected to the control center are installed in the pipes before and after each heat storage module in both the heat storage circulation pipeline and the heat release circulation pipeline. This allows for better monitoring and control of the heat storage charging and heat release power generation processes by detecting the inflow and outflow temperatures of each heat storage module.
[0033] Furthermore, the heat storage switch valve at the input end of the first heat storage module, the heat storage switch valve at the first heat storage bypass branch, the heat storage switch valve at the second heat storage bypass branch, the heat storage switch valve at the first heat storage return branch, the heat storage switch valve at the input end of the second heat storage module, the heat storage switch valve at the output end of the second heat storage module, the heat storage switch valve at the input end of the third heat storage module, and the heat storage switch valve at the second heat storage return branch are all flow regulating switch valves capable of flow regulation; each flow regulating switch valve is connected to the control center.
[0034] In this way, when heating and storing energy for multiple thermal storage modules simultaneously, if the required heating levels for each module differ, the flow rate of the fluid medium (for thermal storage) passing through the module requiring higher heat storage can be increased, while the flow rate through the module requiring lower heat storage can be decreased. This allows the heat storage ratio of each heated module to quickly reach a uniform level, at which point the flow rate for each module can be restored to the same level. Utilizing a heating method from high to low heat storage better ensures heat utilization efficiency. Therefore, this approach maximizes heat utilization efficiency and minimizes heat loss during heating under any demand conditions.
[0035] In summary, the Carnot battery energy storage system of the present invention has the advantages of high energy utilization, better output adjustability, fast heat storage response, high heating efficiency and good stability. Attached Figure Description
[0036] Figure 1 This is a schematic diagram of the overall structure of the Carnot battery energy storage system during implementation. The heat storage circulation pipeline is represented by solid lines, while the heat release circulation pipeline is represented by dashed lines.
[0037] Figure 2 for Figure 1 A frontal sectional view of a standalone thermal storage unit.
[0038] Figure 3 for Figure 2 Left sectional view.
[0039] Figure 4 for Figure 2 A schematic diagram of a single thermal storage module.
[0040] Figure 5 for Figure 3 A schematic diagram of a single thermal storage module. Detailed Implementation
[0041] The present invention will now be described in further detail with reference to specific embodiments.
[0042] In specific implementation: a Carnot battery energy storage system, see [link / reference] Figure 1-5 As shown, the device includes an electric heater 1, a heat storage device 2, a turbine expander 3, and a generator 4. A heat storage circulation pipeline 5 is connected between the electric heater 1 and the heat storage device 2. A heat storage circulation pump 6 is installed on the heat storage circulation pipeline 5, and a heat storage fluid medium is contained within the pipeline. A heat release circulation pipeline 7 is also connected between the heat storage device 2 and the turbine expander 3. A heat release circulation pump 8 is installed on the heat release circulation pipeline 7, and a heat release fluid medium is contained within the pipeline. The power output end of the turbine expander 3 is connected to the input end of the generator 4. The characteristic feature is that the heat storage device 2 includes a first heat storage module 9, a second heat storage module 10, and a third heat storage module 4. Each heat storage module 11 is equipped with a heat storage pipeline channel 12, a heat release pipeline channel 13, and a heat storage chamber 14 containing solid-liquid phase change material. The phase change temperature of the solid-liquid phase change material in the first heat storage module 9, the second heat storage module 10, and the third heat storage module 11 decreases sequentially. The heat storage pipeline channels 12 of the first, second, and third heat storage modules are connected in series in the heat storage circulation pipeline 5 and in series with the electric heater 1. The heat release pipeline channels 13 of the third, second, and first heat storage modules are connected in series in the heat release circulation pipeline 7 and in series with the turbine expander.
[0043] In this way, during charging and energy storage, the electric heater generates heat, which is then transferred sequentially through the first, second, and third heat storage modules by the heat storage fluid medium in the heat storage circulation pipeline, heating the solid-liquid phase change material within each module. After heat exchange in the first heat storage module, the heat storage fluid medium, with a slightly lower temperature, is then heated again by the second heat storage module, which has a lower phase change temperature. After another slight decrease in temperature, it is heated again by the third heat storage module, which has an even lower phase change temperature. Therefore, heat waste is effectively avoided during the heat storage process. Then, during heat release and power generation, the heat release fluid medium in the heat release circulation pipeline gradually preheats from low to medium to high temperatures by passing through the third, second, and first heat storage modules, ultimately reaching a higher temperature to heat the turbine expander and improve the final heating effect. Therefore, this multi-stage heat storage module system in the heat storage and power generation process achieves tiered heating utilization, better avoiding waste and improving energy utilization efficiency.
[0044] The thermal storage device has an overall rectangular structure, with the first thermal storage module 9, the second thermal storage module 10, and the third thermal storage module 11 stacked sequentially from top to bottom. This structure is simple and compact, easy to implement, and can better prevent heat loss from the thermal storage modules.
[0045] In each heat storage module, the heat storage pipeline 12 is located on the lower side of the heat storage chamber 14, and the heat release pipeline 13 is located on the upper side of the heat storage chamber 14; the heat storage pipeline 12 and the heat release pipeline 13 are each wavy and tortuous on the side adjacent to the heat storage chamber 14.
[0046] This allows for more convenient heat storage and release, and improves the efficiency of heat storage and release.
[0047] The solid-liquid phase change material is an inorganic salt mixture phase change material. This has advantages such as low cost, ease of implementation, and convenient adjustment of the phase change temperature.
[0048] The phase transition temperatures of the solid-liquid phase change materials in the first thermal storage module 9, the second thermal storage module 10, and the third thermal storage module 11 are 700℃, 600℃, and 500℃, respectively. This temperature gradient interval is moderate, which is conducive to achieving proportional and synchronous temperature rise and energy storage during sequential heating.
[0049] In each heat storage module, a heat transfer interlayer chamber 15 is also provided on the side adjacent to the heat storage pipeline channel and the heat storage chamber. The heat transfer interlayer chamber 15 is provided with a heat transfer fluid medium. One end of the heat transfer interlayer chamber 15 is connected to a heat transfer pipe 16. The heat transfer pipe 16 is connected to the interior of the heat storage chamber to form a heat transfer network and is connected back to the heat transfer interlayer chamber to form a circulation. A heat transfer circulation pump 17 is provided on the heat transfer pipe.
[0050] In this way, when the heat storage fluid flows through the heat storage pipeline channels of the heat storage module, it first heats the heat transfer jacket chamber, causing the temperature of the heat transfer fluid medium inside to rise rapidly. Then, under the action of the heat transfer circulation pump, the high-temperature heat transfer fluid medium exchanges heat with the solid-liquid phase change material through the heat transfer pipeline network and returns to the heat transfer jacket chamber for reheating, thus forming a circulation and rapidly transferring heat into the heat storage chamber. Therefore, the heat storage efficiency in the heat storage module is greatly improved.
[0051] The heat transfer network includes a main heat transfer pipe 18 horizontally arranged on the side away from the heat storage pipeline channel. Several branch heat transfer pipes 19 are evenly distributed on the main heat transfer pipe 18 and connected in a vertical direction. The branch heat transfer pipes 19 are arranged in a tortuous manner and connected back to the heat transfer jacket chamber.
[0052] This allows for more uniform heating of the solid-liquid phase change material inside the heat storage chamber, avoiding excessive local heating and better ensuring the stability of the device.
[0053] The heat transfer pipe 16 and the heat transfer circulation pump 17 thereon are located outside the heat storage chamber 14.
[0054] This makes it easier to inspect, maintain, and control the heat transfer circulation pump.
[0055] The heat transfer interlayer chamber 15 and the heat storage pipeline channel are further provided with a layer of porous thermally conductive material 20 on the inner wall of the adjacent side. This greatly improves the heat exchange efficiency of the heat storage pipeline channel to the heat transfer interlayer chamber.
[0056] In practice, the porous thermal conductive material is preferably a sintered porous metal material with an average porosity of 50%-85% and a pore size of 10-200 micrometers, so as to better ensure the heat exchange effect.
[0057] The heat transfer fluid medium is a liquid-gas phase change material, and the phase change temperature of the liquid-gas phase change material is higher than that of the solid-liquid phase change material in the heat storage module.
[0058] In this way, the liquid-gas phase change material is normally adsorbed within the porous thermally conductive material. When the heat storage fluid flows through the heat storage pipeline to heat the heat transfer jacket chamber, the liquid-gas phase change material rapidly vaporizes under the action of the porous thermally conductive material, forming a high-temperature heat transfer gas. Then, under the action of the heat transfer circulation pump, the high-temperature heat transfer gas exchanges heat with the solid-liquid phase change material through the heat transfer pipeline network and returns to the heat transfer jacket chamber, thus forming a cycle and achieving rapid and stable heat storage. During this process, because the heat transfer fluid medium is a liquid-gas phase change material, the upper limit of the heating temperature of the solid-liquid phase change material is limited, thus greatly improving the stability of the heating process while ensuring high heating efficiency. In practice, under unheated conditions, the amount of liquid-gas phase change material is limited to that adsorbed within the porous thermally conductive material. This avoids excessive liquid-gas phase change material causing excessive thermal expansion and affecting the stability of the device.
[0059] The phase change temperature of the liquid-gas phase change material is 5-50℃ higher than that of the solid-liquid phase change material in the thermal storage module.
[0060] This is because the phase change temperatures of the solid-liquid phase change materials in the first, second, and third thermal storage modules are 700℃, 600℃, and 500℃, respectively, resulting in significant temperature differences. To heat the first thermal storage module, the electric heater's operating temperature would exceed 700℃. Therefore, when the electric heater needs to supplement heat to the second or third thermal storage module separately, the input temperature of the heat storage fluid medium would far exceed the phase change temperature of the solid-liquid phase change material within the module. This could easily lead to excessively rapid localized heating within the thermal storage module, even vaporization and expansion, significantly reducing the module's stability and lifespan. Therefore, using a liquid-gas phase change material as the heat transfer fluid medium, with a phase change temperature only 5-50℃ higher than the solid-liquid phase change material's phase change temperature, avoids the defects caused by excessively rapid localized heating within the thermal storage module. This better ensures high heat exchange efficiency while improving the device's stability and extending the module's lifespan.
[0061] In practice, the liquid-gas phase change material is preferably a liquid metal, specifically a mixture of sodium, potassium, or a sodium-potassium eutectic alloy. This results in low cost, easy adjustment of the vaporization temperature, and high heat exchange efficiency.
[0062] The turbine expander 3 has one output port and three return ports. A heat release circulation pump 8 is installed on the heat release circulation pipeline 7 leading from the output port of the turbine expander 3 and connected to the third heat storage module. The heat release circulation pipeline leading from the third heat storage module is connected to the second heat storage module, and a third heat release return branch 23 is also connected to this pipeline. A third heat release return branch switch valve 24 is installed on the third heat release return branch 23 and connected back to one of the return ports of the turbine expander 3. The heat release circulation pipeline between the third heat release return branch 23 and the second heat storage module... A second heat release switch valve 25 is also installed on the pipeline; the heat release circulation pipeline from the second heat storage module is connected to the first heat storage module and a second heat release return branch 26 is also connected to the pipeline. A second heat release return branch switch valve 27 is installed on the second heat release return branch 26 and is connected to another return port of the turbine expander 3. A first heat release switch valve 28 is also installed on the heat release circulation pipeline between the second heat release return branch 26 and the first heat storage module; the heat release circulation pipeline from the first heat storage module is connected to the third return port of the turbine expander 3.
[0063] Thus, when the generator's power demand is low, the third heat return branch switch valve can be opened and the second heat return switch valve closed. This ensures that the heat exchange pipeline only passes through the third heat storage module, relying solely on the lowest-temperature third heat storage module to heat and generate electricity for the turbine expander. When the generator's power demand is moderate, the third heat return branch switch valve and the first heat return switch valve can be closed, while the second heat return switch valve and the second heat return branch switch valve can be opened simultaneously. This allows the heat-generating fluid medium to be preheated by the first heat storage module and then heated by the second heat storage module before supplying heat and electricity to the turbine expander, producing a moderate amount of electricity. When the generator's power demand is maximum, the third heat return branch switch valve and the second heat return branch switch valve can be closed, while the second heat return switch valve and the first heat return switch valve can be opened simultaneously. This allows the heat-generating fluid medium to be heated sequentially through the third, second, and first heat storage modules before supplying heat and electricity to the turbine expander, producing the maximum amount of electricity. Therefore, it can achieve different power outputs according to power supply needs, making the equipment more flexible and versatile, and improving its applicability.
[0064] The electric heater 1 has one output port and three return ports. A heat storage circulation pump 6 is installed on the heat storage circulation pipeline 5 connected to the output port of the electric heater 1 and connected to the first heat storage module. A heat storage switch valve 31 for the input end of the first heat storage module is installed on the heat storage circulation pipeline near the input end of the first heat storage module. A first heat storage bypass branch 32 and a second heat storage bypass branch 33 are respectively connected to the heat storage circulation pipeline between the heat storage circulation pump 6 and the heat storage switch valve 31. A first heat storage bypass branch heat storage switch valve 34 is installed on the first heat storage bypass branch 32 and connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. A second heat storage bypass branch heat storage switch valve 35 is installed on the second heat storage bypass branch 33 and connected to the heat storage circulation pipeline between the second heat storage module and the third heat storage module. A first heat storage return port is also connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. Branch 36 is connected to a return port of the return heater 1. A first heat storage return branch 36 is also equipped with a first heat storage return branch heat storage switch valve 37. A second heat storage module input end heat storage switch valve 38 is also installed on the heat storage circulation pipeline between the first heat storage return branch 36 and the first heat storage bypass branch 32. A second heat storage module output end heat storage switch valve 39 and a third heat storage module input end heat storage switch valve 40 are respectively set on both sides of the second heat storage bypass branch on the heat storage circulation pipeline between the second heat storage module and the third heat storage module. A second heat storage return branch 41 is also set on the heat storage circulation pipeline between the second heat storage module output end heat storage switch valve 39 and the third heat storage module input end heat storage switch valve 40 and connected to another return port of the return heater 1. A second heat storage return branch 41 is equipped with a second heat storage return branch heat storage switch valve 42. The heat storage circulation pipeline at the output end of the third heat storage module is connected to the third return port of the return heater.
[0065] Thus, through the aforementioned piping and control valve structure, seven heating methods can be achieved, including individual heating of the three heat storage modules, heating in pairs, or heating together. Specifically, when heating all three heat storage modules simultaneously, simply close the heat storage switch valves on the two heat storage bypass branches and the two heat storage return branches, and open the remaining heat storage switch valves to achieve series heating of the first, second, and third heat storage modules sequentially. When heating only the first heat storage module, simply open the heat storage switch valve at the input end of the first heat storage module and the heat storage switch valve on the first heat storage return branch, and close the remaining heat storage switch valves to achieve heating of the first heat storage module alone. When heating both the first and second heat storage modules simultaneously, simply open the heat storage switch valves at the input end of the first heat storage module, the input end of the second heat storage module, and the second heat storage return branch, and close the remaining heat storage switch valves to achieve series heating of the first and second heat storage modules individually. When heating both the first and third thermal storage modules simultaneously is required, simply open the thermal storage switch valves at the input, return, and bypass branches of the first and third thermal storage modules, and close the remaining thermal storage switch valves to achieve parallel heating for each module. When heating only the second thermal storage module is required, simply open the thermal storage switch valves at the bypass, output, and return branches of the second and third thermal storage modules, and close the remaining thermal storage switch valves to achieve parallel heating for both modules. When only the third heat storage module needs to be heated, simply open the heat storage switch valve of the second heat storage bypass branch and the heat storage switch valve at the input end of the third heat storage module, and close the other heat storage switch valves to achieve independent heating for the third heat storage module.
[0066] Therefore, the aforementioned piping and control valve structure can achieve heating control of a single module, any two modules, or all modules of the thermal storage system, enabling it to effectively handle situations where heating is required after any thermal storage module releases heat. Furthermore, when two or more thermal storage modules need to be heated simultaneously, except in cases where the first and third thermal storage modules need to be heated simultaneously, series heating from high to low temperature can be achieved, better avoiding energy waste and improving energy storage and utilization efficiency during the heating process.
[0067] The first, second, and third heat storage modules each have a thermometer 43 installed in their respective heat storage chambers, which is connected to a control center (not shown in the figure). The control center is also connected to each heat storage switch valve and each heat release switch valve.
[0068] This allows for better detection of the internal heat storage status of each heat storage module, enabling the assessment and control of the heat storage charging and heat release power generation processes.
[0069] The thermal storage circulation pipeline and the thermal release circulation pipeline are each equipped with a thermometer connected to the control center in the pipelines located before and after each thermal storage module. This allows for better monitoring of the inflow and outflow temperatures of each thermal storage module, thus aiding in the judgment and control of the thermal storage charging and thermal release power generation processes.
[0070] Among them, the first thermal storage module input terminal thermal storage switch valve 31, the first thermal storage bypass branch thermal storage switch valve 34, the second thermal storage bypass branch thermal storage switch valve 35, the first thermal storage return branch thermal storage switch valve 37, the second thermal storage module input terminal thermal storage switch valve 38, the second thermal storage module output terminal thermal storage switch valve 39, the third thermal storage module input terminal thermal storage switch valve 40, and the second thermal storage return branch thermal storage switch valve 42 are all flow regulating switch valves capable of flow regulation; each flow regulating switch valve is connected to the control center.
[0071] In this way, when heating and storing energy for multiple thermal storage modules simultaneously, if the required heating levels for each module differ, the flow rate of the fluid medium (for thermal storage) passing through the module requiring higher heat storage can be increased, while the flow rate through the module requiring lower heat storage can be decreased. This allows the heat storage ratio of each heated module to quickly reach a uniform level, at which point the flow rate for each module can be restored to the same level. Utilizing a heating method from high to low heat storage better ensures heat utilization efficiency. Therefore, this approach maximizes heat utilization efficiency and minimizes heat loss during heating under any demand conditions.
[0072] Compared with existing technologies, this invention has the following significant advantages: 1. Revolutionary improvement in heat transfer efficiency. Utilizing the "evaporation-condensation" phase change heat transfer mechanism of gas-liquid phase change materials, its equivalent heat transfer coefficient is several orders of magnitude higher than that of pure PCM, completely solving the core problem of slow heat charging / releasing rates in solid-liquid phase change materials and achieving high power density heat storage. 2. High energy density and compact structure. While achieving extremely high heat transfer power, it retains the advantages of high latent heat storage density of solid-liquid phase change materials. Multi-layer unit three-dimensional integration significantly reduces the system volume compared to traditional storage tanks. 3. Realization of physical multi-temperature zones and intelligent management. By encapsulating solid-liquid phase change materials with different melting points in different unit layers, multiple discrete and clearly defined temperature zones are realized in the physical structure. This provides the hardware foundation for precise heat storage and cascade utilization based on artificial intelligence, greatly improving the overall efficiency and economy of the system under partial load. 4. Capable of temperature-controlled operation with high reliability. The circulation of the working fluid within the unit is entirely driven by capillary force, with no moving parts, resulting in more stable operation at high temperatures, longer lifespan, and lower maintenance costs. 5. The system offers excellent flexibility and scalability. The modular design allows for flexible configuration of system capacity by increasing or decreasing the number of modules, facilitating standardized production and field deployment.
Claims
1. A Carnot battery energy storage system, comprising an electric heater, a heat storage device, a turbine expander, and a generator, wherein a heat storage circulation pipeline is further connected between the electric heater and the heat storage device, a heat storage circulation pump is installed on the heat storage circulation pipeline and a heat storage fluid medium is disposed within the pipeline, and a heat release circulation pipeline is further connected between the heat storage device and the turbine expander, a heat release circulation pump is installed on the heat release circulation pipeline and a heat release fluid medium is disposed within the pipeline, and the power output end of the turbine expander is connected to the input end of the generator; characterized in that, The heat storage device includes a first heat storage module, a second heat storage module, and a third heat storage module. Each heat storage module is equipped with a heat storage pipeline channel, a heat release pipeline channel, and a heat storage chamber containing solid-liquid phase change material. The phase change temperature of the solid-liquid phase change material in the first, second, and third heat storage modules decreases sequentially. The heat storage pipeline channels of the first, second, and third heat storage modules are connected in series in a heat storage circulation pipeline and connected in series with an electric heater. The heat release pipeline channels of the third, second, and first heat storage modules are connected in series in a heat release circulation pipeline and connected in series with a turboexpander.
2. The Carnot battery energy storage system as described in claim 1, characterized in that, The thermal storage device has an overall rectangular structure, and the first thermal storage module, the second thermal storage module, and the third thermal storage module are stacked sequentially from top to bottom.
3. The Carnot battery energy storage system as described in claim 1, characterized in that, In each heat storage module, the heat storage pipeline is located on the lower side of the heat storage chamber, and the heat release pipeline is located on the upper side of the heat storage chamber; both the heat storage pipeline and the heat release pipeline are wavy and tortuous on the side adjacent to the heat storage chamber.
4. The Carnot battery energy storage system as described in claim 1, characterized in that, The solid-liquid phase change material is an inorganic salt mixture phase change material; The phase transition temperatures of the solid-liquid phase change materials in the first, second, and third thermal storage modules are 700℃, 600℃, and 500℃, respectively.
5. The Carnot battery energy storage system as described in claim 1, characterized in that, In each heat storage module, a heat transfer interlayer chamber is also provided on the side adjacent to the heat storage pipeline channel and the heat storage chamber. The heat transfer interlayer chamber is provided with a heat transfer fluid medium. One end of the heat transfer interlayer chamber is connected to a heat transfer pipe. The heat transfer pipe is connected into the heat storage chamber to form a heat transfer network and is connected back to the heat transfer interlayer chamber to form a circulation. A heat transfer circulation pump is provided on the heat transfer pipe.
6. The Carnot battery energy storage system as described in claim 5, characterized in that, The heat transfer network includes a main heat transfer pipe horizontally arranged on the side away from the heat storage pipeline channel. Several branch heat transfer pipes connected vertically are evenly distributed on the main heat transfer pipe. The branch heat transfer pipes are arranged in a tortuous manner and connected back to the heat transfer jacket chamber.
7. The Carnot battery energy storage system as described in claim 5, characterized in that, The heat transfer pipe and the heat transfer circulation pump on it are located outside the heat storage chamber; A layer of porous thermally conductive material is also provided on the inner wall of the heat transfer jacket chamber and the heat storage pipeline channel on the adjacent side. The heat transfer fluid medium is a liquid-gas phase change material, and the phase change temperature of the liquid-gas phase change material is higher than that of the solid-liquid phase change material in the heat storage module.
8. The Carnot battery energy storage system as described in claim 1, characterized in that, The turboexpander has one output port and three return ports. A heat release circulation pump is installed on the heat release circulation pipeline from the output port of the turboexpander and connected to a third heat storage module. The heat release circulation pipeline from the third heat storage module is connected to a second heat storage module, and a third heat release return branch is also connected to this pipeline. A third heat release return branch switch valve is installed on the third heat release return branch and connected to one return port of the turboexpander. A second heat release switch valve is also installed on the heat release circulation pipeline between the third heat release return branch and the second heat storage module. The heat release circulation pipeline from the second heat storage module is connected to a first heat storage module, and a second heat release return branch is also connected to this pipeline. A second heat release return branch switch valve is installed on the second heat release return branch and connected to another return port of the turboexpander. A first heat release switch valve is also installed on the heat release circulation pipeline between the second heat release return branch and the first heat storage module. The heat release circulation pipeline from the first heat storage module is connected to the third return port of the turboexpander.
9. The Carnot battery energy storage system as described in claim 8, characterized in that, The electric heater has one output port and three return ports. A heat storage circulation pump is installed on the heat storage circulation pipeline leading from the output port of the electric heater and connected to the first heat storage module. A heat storage switch valve for the input end of the first heat storage module is installed on the heat storage circulation pipeline near the input end of the first heat storage module. A first heat storage bypass branch and a second heat storage bypass branch are also connected to the heat storage circulation pipeline between the heat storage circulation pump and the input end heat storage switch valve of the first heat storage module. A first heat storage bypass branch heat storage switch valve is installed on the first heat storage bypass branch and connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. A second heat storage bypass branch heat storage switch valve is installed on the second heat storage bypass branch and connected to the heat storage circulation pipeline between the second heat storage module and the third heat storage module. A first heat storage module is also connected to the heat storage circulation pipeline between the first heat storage module and the second heat storage module. A return branch is connected to a return port of the recharge heater. A first heat storage return branch heat storage switch valve is also installed on the first heat storage return branch. A second heat storage module input heat storage switch valve is also installed on the heat storage circulation pipeline between the first heat storage return branch and the first heat storage bypass branch. A second heat storage module output heat storage switch valve and a third heat storage module input heat storage switch valve are respectively installed on both sides of the second heat storage bypass branch on the heat storage circulation pipeline between the second heat storage module output heat storage switch valve and the third heat storage module input heat storage switch valve. A second heat storage return branch is also provided on the heat storage circulation pipeline between the second heat storage module output heat storage switch valve and the third heat storage module input heat storage switch valve and is connected to another return port of the recharge heater. A second heat storage return branch heat storage switch valve is installed on the second heat storage return branch. The heat storage circulation pipeline at the output of the third heat storage module is connected to the third return port of the recharge heater.
10. The Carnot battery energy storage system as described in claim 9, characterized in that, Each of the first, second, and third heat storage modules has a thermometer installed in its heat storage chamber and connected to the control center. The control center is connected to each heat storage switch valve and each heat release switch valve. The thermometers in the heat storage circulation pipeline and the heat release circulation pipeline, located before and after each heat storage module, are connected to the control center. The first thermal storage module input terminal thermal storage switch valve, the first thermal storage bypass branch thermal storage switch valve, the second thermal storage bypass branch thermal storage switch valve, the first thermal storage return branch thermal storage switch valve, the second thermal storage module input terminal thermal storage switch valve, the second thermal storage module output terminal thermal storage switch valve, the third thermal storage module input terminal thermal storage switch valve, and the second thermal storage return branch thermal storage switch valve are all flow regulating switch valves capable of flow regulation; each flow regulating switch valve is connected to the control center.