Single-tank heat storage system and heat charging and discharging method thereof

Abstract

The invention discloses a single-tank heat storage system and a heat charging and discharging method thereof. The single-tank heat storage system comprises a storage tank, and the storage tank is filled with a mixed heat storage medium of heat storage fluid and particles; the heat exchanger is arranged outside the storage tank; the heat transfer modules are filled with phase change working media, and one part of each heat transfer module is located in the heat exchanger and makes heat transfer contact with a heat exchange medium in the heat exchanger; at least one part, located outside the heat exchanger, of the heat transfer module is located in the storage tank, is buried in the mixed heat storage medium and is in heat transfer contact with the mixed heat storage medium; each heat supply module comprises a part which is positioned in the storage tank and is used for providing a heat source to heat the mixed heat storage medium in the storage tank; and moreover, the multiple heat transfer modules are arranged in the storage tank in a dispersed mode, the multiple heat supply modules are arranged in the storage tank in a dispersed mode, and the heat transfer modules and the heat supply modules are kept staggered.

Description

Technical Field

[0001] The present invention relates to a single-tank heat storage system and a method for charging and discharging heat thereof, belonging to the field of energy storage. Background Art

[0002] Currently, the main heat storage media for heat storage are molten salt and particles. Among them, molten salt is used for heat storage and has the characteristics of good heat transfer. Currently, it has been successfully applied in fields such as solar thermal power generation, but the cost of molten salt medium is high; particle medium is used for heat storage, with low cost, but the heat transfer performance of particles is poor. Therefore, some studies have proposed mixing molten salt and particles for common heat storage to complement their advantages. However, how to extract heat is a major problem faced by this method.

[0003] The current mainstream and mature heat storage method is the double-tank system. The molten salt is electrically heated and then stored in the hot tank, and then when needed, the molten salt is taken out, heat-exchanged and cooled, and then stored in the molten salt cold tank. However, if the double-tank system is applied to the hybrid heat storage of particles and molten salt, a major problem is that the molten salt transported in the system will carry particle impurities, which will damage the heat exchanger, pump, etc. at the back end.

[0004] In addition, other heat storage methods also include single-tank heat storage. If the hybrid heat storage of molten salt and particles adopts the current single-tank heat storage, that is, the heat storage medium is placed in a tank without moving, and other heat transfer media such as air are introduced for heat extraction at the same time, then as the heat extraction process progresses, the temperature of the single tank will continuously decrease, and the temperature in the tank will show uneven temperature in various regions such as a sloping temperature layer, and then it cannot be ensured that the temperature of the output air is constant, and it is difficult for the back-end system to operate stably. Summary of the Invention

[0005] Based on the current needs, the present invention provides a single-tank heat storage system and a method for charging and discharging heat thereof, which can realize the hybrid heat storage of particles and molten salt and avoid the above problems at the same time.

[0006] The technical solution of the present invention is as follows:

[0007] A single-tank heat storage system, comprising:

[0008] A storage tank, the inside of which is filled with a hybrid heat storage medium of a heat storage fluid and particles;

[0009] A heat exchanger, which is arranged outside the storage tank;

[0010] A plurality of heat transfer modules, which are filled with a phase change working fluid. A part of the heat transfer module is located in the heat exchanger and is in heat transfer contact with the heat transfer medium in the heat exchanger. At least a part of the heat transfer module outside the heat exchanger is located in the storage tank and buried in the hybrid heat storage medium and is in heat transfer contact with the hybrid heat storage medium;

[0011] Multiple heat supply modules, the heat supply module including a part located in the storage tank and providing a heat source to heat the mixed heat storage medium in the storage tank; and,

[0012] Multiple of the heat transfer modules are dispersedly arranged in the storage tank, multiple of the heat supply modules are dispersedly arranged in the storage tank, and the heat transfer modules and the heat supply modules are staggered from each other.

[0013] Wherein, the heat storage fluid can be heat-conducting oil or molten salt. Wherein, the molten salt remains in a liquid state under the use condition.

[0014] Preferably, in the single-tank heat storage system, the heat exchanger is located above the storage tank.

[0015] In a preferred embodiment, the heat exchanger is connected to the storage tank, and there is a space at the connection allowing the heat transfer module to pass through.

[0016] In a preferred embodiment, the heat transfer module is a heat pipe, the head of the heat pipe is located in the heat exchanger, and at least a part of the portion outside the head of the heat pipe is located in the storage tank and buried in the mixed heat storage medium, in heat transfer contact with the mixed heat storage medium.

[0017] In an embodiment, the heat pipe includes a heat release section and a heat absorption section from top to bottom, wherein the heat release section is located in the heat exchanger and the heat absorption section is located in the storage tank; during operation, the phase change working fluid inside the heat pipe absorbs the heat of the mixed heat storage medium in the heat absorption section, vaporizes, then flows upward to the heat release section, releases heat through liquefaction, and transfers it to the heat extraction medium in the heat exchanger, and the liquefied phase change working fluid then flows back to the heat absorption section to continue absorbing heat, realizing cyclic operation; correspondingly, the heat exchanger includes a working area, and the heat release section of the heat pipe is located in the working area of the heat exchanger.

[0018] In a preferred embodiment, the heat pipe further includes an adiabatic section located between the heat release section and the heat absorption section, and the heat release section and the adiabatic section form the head of the heat pipe and are located in the heat exchanger; the adiabatic section separates the heat release section from the heat absorption section and ensures that the vaporization and liquefaction behaviors of the phase change working fluid can be separated; correspondingly, the heat exchanger includes a connection area, and the working area of the heat exchanger, the connection area of the heat exchanger, and the tank body are connected in sequence from top to bottom; wherein, the adiabatic section of the heat pipe is located in the connection area of the heat exchanger and no heat exchange occurs.

[0019] In a preferred embodiment, the heat absorption section of the heat pipe is provided with a first component for expanding the heat transfer area.

[0020] In a preferred embodiment, a second component for enhancing the convective heat transfer coefficient is provided on the heat release section of the heat pipe.

[0021] Preferably, the first component for enlarging the heat transfer area on the heat absorption section of the heat pipe is a plurality of flat fins, and the plurality of flat fins are uniformly arranged along the circumferential direction of the heat pipe.

[0022] Preferably, the second component for enhancing the convective heat transfer coefficient on the heat release section of the heat pipe is a spiral fin.

[0023] In a preferred embodiment, the heat supply module includes a plurality of insertion pipes or through pipes inserted into the storage tank, and a heat supply unit is included in the insertion pipes or through pipes.

[0024] In a preferred embodiment, the plurality of insertion pipes or through pipes are inserted into the storage tank from the side wall of the tank body of the storage tank, and the plurality of insertion pipes or through pipes are arranged in layers in the storage tank.

[0025] In a preferred embodiment, the cross-sections of the plurality of heat pipes are arranged in a ring shape in the tank body, and are arranged in one circle or multiple concentric circles. The plurality of insertion pipes or through pipes are arranged in a layered and crosswise manner in the storage tank, and the heat pipes and the insertion pipes or through pipes are evenly dispersed and kept staggered.

[0026] In a preferred embodiment, the heat exchanger includes an inlet pipe located at a lower position and an outlet pipe located at a higher position, and a plurality of baffle plates are provided in the heat exchanger. When the heat exchange operation is carried out, the heat-taking medium enters the heat exchanger from the inlet pipe, and under the obstruction of the baffle plates, it undergoes turbulent flow and absorbs heat, and then flows out from the outlet pipe after heating up.

[0027] In a preferred embodiment, the height-diameter ratio of the storage tank is less than or equal to 2.

[0028] In a preferred embodiment, the top of the tank body of the storage tank is conical.

[0029] In a preferred embodiment, the heat source of the insertion pipe or through pipe is electric heating or a heat fluid. When electric heating is used as the heat source, the insertion pipe or through pipe is an electric heating pipe, or an electric heating pipe is inserted into the insertion pipe or through pipe and the insertion pipe or through pipe is in close contact with the electric heating pipe; when a heat fluid is used as the heat source, the heat fluid is directly introduced into one end of the through pipe and flows out from the other end, and the heat is transferred to the mixed heat storage medium through the through pipe by means of convective heat transfer. When the heat source is electric heating, the heat supply module can be an insertion pipe or a through pipe, and when the heat source is a heat fluid, the heat supply module is a through pipe.

[0030] In a preferred embodiment, the working area of the heat exchanger, the connection area of the heat exchanger, and the tank body of the storage tank are sequentially connected by flanges from top to bottom.

[0031] The present invention also provides a method for charging and discharging heat of the single-tank heat storage system described above, including:

[0032] When there is a heat source, the heat source is input to the heat supply module, and the mixed heat storage medium in the storage tank is gradually heated to the required temperature to complete the heat charging process. During the heat charging stage, no heat extraction medium passes through the heat exchanger.

[0033] When extracting heat, a low-temperature heat extraction medium is introduced into the heat exchanger and absorbs the heat released by the liquefaction of the phase-change working fluid in a part of the heat transfer module in the heat exchanger to increase in temperature.

[0034] In a preferred embodiment, electric heating is used as the heat source for heat charging. By using the Joule heating of the electric heating tube, the temperature of the heat supply module is heated, and heat transfer occurs with the heat storage fluid medium in the tank. The heat storage fluid medium then heats the particulate medium through direct contact heat transfer, gradually raising the temperature of the mixed heat storage medium throughout the storage tank to 540 - 565 °C.

[0035] In a preferred embodiment, hot gas is used as the heat source for heat charging. The hot gas is continuously input into the heat supply module, and the heat supply module exchanges heat indirectly with the heat storage fluid medium in the tank. The heat storage fluid medium then heats the particulate medium through direct contact heat transfer, and thus the temperature of the mixed heat storage medium throughout the storage tank gradually rises to 540 - 565 °C.

[0036] In a preferred embodiment, during the heat discharging stage, a low-temperature heat extraction medium is introduced into the heat exchanger and absorbs the heat released by the liquefaction of the phase-change working fluid in a part of the heat transfer module located in the heat absorber to increase in temperature. The phase change temperature of the phase-change working fluid is in the range of 240 - 260 °C. During the heat discharging process, the part of the heat transfer module in the heat exchanger is maintained at this temperature range. At the same time, the heat extraction medium enters the heat exchanger at a stable temperature and exits at another stable temperature after heat exchange in the heat exchanger.

[0037] In a preferred embodiment, as the heat discharging process progresses, the overall temperature in the storage tank gradually decreases. At this time, the flow rate of the heat extraction medium is gradually reduced.

[0038] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0039] First, the mixing of particles and molten salt for heat storage is successfully achieved, combining the characteristics of low-cost particles and good heat transfer properties of molten salt. Different from the traditional dual-tank system that requires continuous inflow / outflow of molten salt into / from the storage tank, this does not cause the molten salt to carry particle impurities and affect the backend equipment. Moreover, the molten salt can be replaced with heat transfer oil, and those skilled in the art can perform appropriate routine debugging on this basis to obtain an appropriate single-tank heat storage system with heat transfer oil and particles.

[0040] Second, compared with the existing single-tank systems, in the single-tank heat storage system of the present invention, the storage tank utilizes the characteristics of the phase change working medium filled in the heat transfer module to keep the temperature difference at the heat exchange end of the heat exchanger constant during heat extraction, which is beneficial to the operation of the backend power equipment; at the same time, heat charging and heat discharging can be carried out simultaneously, such as the abandoned photovoltaic power during the day and the valley electricity or abandoned wind power at night, and long-term heat charging can be maintained. Even if the temperature in the tank is uneven, it will not affect the temperature of the heat discharging section.

[0041] Third, different from the dual-tank system that needs to consider the extraction of molten salt or heat transfer oil, and also different from the single-tank storage tank that needs to consider increasing the height to ensure the proportion of the inclined temperature layer, the high diameter ratio of the storage tank in this single-tank heat storage system can be made small (less than or equal to 2), that is, the appearance is short and fat. On the one hand, this can reduce the cost of the ground foundation, and on the other hand, it can reduce the heat dissipation of the tank body.

[0042] Of course, it is not necessary for any product implementing the present invention to achieve all the above-mentioned advantages simultaneously. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1A is a schematic diagram of the single-tank heat storage system according to an embodiment of the present invention; Figure 1B is Figure 1A the view in the A-A direction in, showing the layout mode of the through pipe and the heat pipe in the cross-sectional direction;

[0044] Figure 2 is a schematic diagram of the heat source utilization mode of the single-tank heat storage system according to an embodiment of the present invention;

[0045] Figure 3 is a schematic diagram of the heat pipe structure of the single-tank heat storage system according to an embodiment of the present invention;

[0046] Figure 4 is a schematic diagram of the heat exchanger structure of the single-tank heat storage system according to an embodiment of the present invention;

[0047] In the figure: 1. Storage tank; 2. Particle medium; 3. Heat exchanger; 4. Heat pipe; 5. Through pipe; 6. Heat discharging section; 7. Adiabatic section; 8. Heat absorption section; 9. Flat fin; 10. Spiral fin; 11. Working area; 12. Connection area; 13. Inlet pipe; 14. Outlet pipe; 15. Baffle plate; 16. Flange; 17. Electric heating pipe; 18. Hot fluid. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0048] The present invention provides a single-tank heat storage system and its charging and discharging method, which can realize the hybrid heat storage of particle molten salt. In addition, the molten salt can also be replaced by heat transfer oil to realize the hybrid heat storage of particle heat transfer oil.

[0049] The single-tank heat storage system of the present invention includes:

[0050] A storage tank, the interior of which is filled with a hybrid heat storage medium of a heat storage fluid and particles;

[0051] A heat exchanger, which is arranged outside the storage tank;

[0052] A plurality of heat transfer modules, which are filled with a phase change working fluid. A part of the heat transfer module is located inside the heat exchanger and is in heat transfer contact with the heat transfer medium inside the heat exchanger. At least a part of the heat transfer module located outside the heat exchanger is located inside the storage tank and buried in the hybrid heat storage medium, and is in heat transfer contact with the hybrid heat storage medium;

[0053] A plurality of heat supply modules, the heat supply modules including parts located inside the storage tank and providing a heat source to heat the hybrid heat storage medium inside the storage tank; and,

[0054] A plurality of the heat transfer modules are dispersedly arranged inside the storage tank, a plurality of the heat supply modules are dispersedly arranged inside the storage tank, and the heat transfer modules and the heat supply modules are kept staggered.

[0055] The hybrid heat storage medium of the heat storage fluid and particles can be a hybrid heat storage medium of heat transfer oil and particles, or a hybrid heat storage medium of molten salt and particles. In the following specific statements and embodiments, the hybrid heat storage medium of molten salt and particles will be taken as an example to elaborate on the single-tank heat storage system. Those skilled in the art can, on this basis, combine conventional technical means in the field to obtain a single-tank heat storage system applicable to the hybrid heat storage medium of heat transfer oil and particles.

[0056] The present invention heats the hybrid heat storage medium of the heat storage fluid and particles inside the storage tank by setting a heat supply module inside the storage tank, transfers the heat to outside the storage tank through a heat transfer module filled with a phase change working fluid and in heat transfer contact with the hybrid heat storage medium of the heat storage fluid and particles, and realizes heat storage and heat extraction using the hybrid heat storage medium of the heat storage fluid and particles in a single storage tank by transferring the heat of the heat transfer module to the heat extraction medium in the heat exchanger arranged outside the storage tank. Compared with the existing single-tank heat storage method, the present invention solves the problem that the temperature in each area is uneven in the existing single-tank heat extraction method, resulting in the inability to ensure that the output air temperature is constant, making it difficult for the backend system to operate stably. And a plurality of the heat transfer modules are dispersedly arranged inside the storage tank, a plurality of the heat supply modules are dispersedly arranged inside the storage tank, and the heat transfer modules and the heat supply modules are kept staggered, which can ensure the relative uniformity of heating and heat transfer throughout the storage tank body.

[0057] In the following preferred embodiments, molten salt is taken as an example for further limitation.

[0058] Preferably, all of the heat transfer modules located outside the heat exchanger are located inside the storage tank and buried in the mixed heat storage medium, and are in heat transfer contact with the mixed heat storage medium.

[0059] In a preferred embodiment, a single-tank heat storage system provided by the present invention includes a storage tank, and the inside of the storage tank is filled with a mixed heat storage medium of molten salt and particles; a heat exchanger is connected above the tank body of the storage tank, and a plurality of heat pipes are arranged inside the storage tank. The heat pipes are filled with a phase change working fluid, the head of the heat pipe is located inside the heat exchanger, and a part or all of the remaining part of the heat pipe is located inside the storage tank and buried in the mixed heat storage medium of molten salt and particles and is in direct contact with the heat storage medium; moreover, a plurality of insertion pipes or through pipes penetrate through the storage tank, and the insertion pipes or through pipes provide a heat source to heat the mixed heat storage medium inside the storage tank; wherein, a plurality of the heat pipes are dispersedly arranged inside the storage tank, a plurality of insertion pipes or through pipes are dispersedly arranged inside the storage tank, and the heat pipes are staggered from the through pipes, or the heat pipes are staggered from the insertion pipes.

[0060] In the single-tank heat storage system with the aforementioned preferred structure, setting a heat exchanger above the storage tank is beneficial for the phase change working fluid to rise into the heat exchanger after gasification and to flow back by gravity after releasing heat and liquefying, realizing low-energy consumption recycling; setting the heat transfer module as a tube shape is convenient for dispersed arrangement and also convenient for the phase change working fluid to rise after gasification; burying most or all of the heat pipes into the mixed heat storage medium inside the storage tank is convenient for the phase change working fluid inside the heat pipes to adsorb more heat; setting the head of the heat pipe inside the heat exchanger is convenient for the phase change working fluid inside the heat pipe to absorb heat, gasify and rise, and then exchange heat with the heat extraction medium inside the heat exchanger; setting the heat supply module as insertion pipes and through pipes, on the one hand, the arrangement of inserting or penetrating through the tank body of the storage tank is convenient for the introduction and export of the heating medium, and on the other hand, setting the shape as a tube shape is convenient for uniform and dispersed arrangement, and thus convenient for the uniformity of heating; and a plurality of the heat pipes are dispersedly arranged inside the storage tank, a plurality of the insertion pipes or through pipes are dispersedly arranged inside the storage tank, and the heat pipes are staggered from the insertion pipes or through pipes, which can ensure the basic uniformity of heating and heat transfer in the entire storage tank body.

[0061] When the single-tank heat storage system with the foregoing preferred structure is in use, the heat pipe part buried in the mixed heat storage medium can absorb the heat of the mixed heat storage medium to vaporize the phase change working medium therein. Subsequently, through the heat pipe itself, the vaporized phase change working medium is transmitted upward, and the heat is transferred to the heat extraction medium in the heat exchanger. The dispersed arrangement of the heat pipes can ensure that the heat in various parts of the storage tank is transmitted to the heat exchanger more evenly. The dispersed arrangement of multiple insertion pipes or through pipes can ensure that the mixed heat storage medium of molten salt and particles in the storage tank is heated more evenly. Among them, multiple heat pipes are dispersed in the storage tank, and multiple insertion pipes and through pipes are dispersed in the storage tank. The heat pipes and the through pipes are staggered, which can ensure that the mixed heat storage medium of molten salt and particles in the storage tank is heated more evenly and at the same time, the heat of the mixed heat storage medium in various parts of the storage tank is transmitted to the heat exchanger more evenly. Moreover, the selection of the phase change working medium as the medium for heat absorption, heat conduction, and heat release ensures that the temperature difference at the heat exchange end of the heat exchanger remains constant during heat extraction.

[0062] Preferably, the heat pipe is divided into a heat release section, an adiabatic section, and a heat absorption section from top to bottom. The heat release section and the adiabatic section form the head of the heat pipe and are located in the heat exchanger, and the heat absorption section is located in the storage tank. During operation, the phase change working medium inside the heat pipe absorbs the heat of the mixed heat storage medium of particles and molten salt in the heat absorption section, vaporizes, and then flows upward to reach the heat release section, releases heat through liquefaction, and transfers it to the heat extraction medium in the heat exchanger. The liquefied phase change working medium then flows back to the heat absorption section by gravity to continue absorbing heat, realizing cyclic operation. The adiabatic section is used to separate the heat release section from the heat absorption section and ensure that the vaporization and liquefaction behaviors of the phase change working medium can be separated. Correspondingly, the heat exchanger includes a working area and a connection area. From top to bottom, the working area of the heat exchanger, the connection area of the heat exchanger, and the tank body are connected in sequence. Among them, the heat release section of the heat pipe is located in the working area of the heat exchanger, and the adiabatic section of the heat pipe is located in the connection area of the heat exchanger and no heat exchange occurs. Here, the specific structural settings of the heat pipe and the heat exchanger and their corresponding relationships are provided, the settings of the heat release section and the heat absorption section of the heat pipe of the single-tank heat storage system and the corresponding settings of the heat exchanger are provided, and the adiabatic section of the heat pipe and the corresponding connection area of the heat exchanger are also provided here, so that no heat exchange occurs in this area, ensuring that the vaporization and liquefaction behaviors of the phase change working medium can be clearly separated. In an alternative embodiment, the heat pipe may only include a heat release section and a heat absorption section without an adiabatic section. At this time, the heat exchanger only includes a working area without a connection area.

[0063] Preferably, the heat absorption section of the heat pipe is provided with flat fins, and the heat dissipation section of the heat pipe is provided with spiral fins. The particles and the molten salt mixed heat storage medium transfer heat to the heat absorption section of the heat pipe mainly in the form of heat conduction and natural convection. Therefore, flat fins are installed on the outer wall of the heat absorption section to expand the heat transfer area. The heat extraction medium in the heat exchanger absorbs the energy of the heat dissipation section of the heat pipe through forced convection heat transfer. Therefore, spiral fins are installed on the outer wall of the heat dissipation section to enhance the convective heat transfer coefficient. The flat fin is a specific structure of the first component for expanding the heat transfer area, and those skilled in the art can also choose other structures with similar functions to replace it. The spiral fin is a specific structure of the second component for enhancing the convective heat transfer coefficient, and those skilled in the art can also choose other structures with similar functions to replace it.

[0064] More preferably, the heat absorption section of the heat pipe is provided with a plurality of flat fins, and the plurality of flat fins are evenly arranged along the circumferential direction of the heat pipe to facilitate uniform heat absorption.

[0065] In a preferred embodiment of the present invention, a plurality of the insertion pipes or through pipes are inserted into the storage tank from the side wall of the tank body of the storage tank, and the plurality of insertion pipes or through pipes are arranged in layers in the storage tank. This preferred setting method is easy to operate and better ensures the efficiency and effect of heating and heat transfer.

[0066] In a further preferred embodiment, the heat pipes are arranged in a ring shape in the tank body and are arranged in one or more concentric circles. The through pipes are arranged in a layered and crossed manner in the storage tank, and the heat pipes and the through pipes are evenly distributed and kept staggered. This setting method of the heat pipes and the through pipes is easy to operate and better ensures the efficiency and effect of heating and heat transfer. The so-called uniform distribution means that the distance difference between the pipe bodies is not significantly too large.

[0067] Preferably, the heat exchanger includes an inlet pipe located at a lower position and an outlet pipe located at a higher position, and a plurality of baffle plates are provided in the heat exchanger. When the heat exchange work is carried out, the heat extraction medium enters the heat exchanger from the inlet pipe, and under the blocking action of the baffle plates, it undergoes turbulent flow and absorbs heat, and then flows out from the outlet pipe after heating up. This specific structural setting of the heat exchanger ensures the heat exchange efficiency. The number of baffle plates can be selected by those skilled in the art according to the actual situation, and can be one or more, and no specific limitation is made here.

[0068] Preferably, the height-to-diameter ratio (height / diameter) of the storage tank is less than or equal to 2. Since the single-tank heat storage system of the present invention is different from the double-tank system in that it is necessary to consider taking out the molten salt, and is also different from the existing single-tank storage tank in that it is necessary to consider increasing the height to ensure the proportion of the thermocline layer, the storage tank in the single-tank heat storage system of the present invention can have a small height-to-diameter ratio, that is, a short and fat appearance, which can reduce the cost of the ground foundation on the one hand, and reduce the heat dissipation of the tank on the other hand.

[0069] Preferably, the top of the tank is conical. The conical top of the tank can adapt to the accumulation angle of the particles without dead zones, and maximize the proportion of particles in the mixture of particles and molten salt, so that the volume fraction of particles reaches 60-63%.

[0070] Preferably, the heat of the heating module comes from electric heating or thermal fluid. When electric heating is used as the heat source, the heating module can select the through-tube or the insertion tube, each of which is an electric heating tube, or an electric heating tube is inserted in the insertion tube or through-tube and the through-tube or the insertion tube is tightly fitted with the electric heating tube; when the thermal fluid is used as the heat source, the heating module can select the through-tube, directly pass the thermal fluid from one end of the through-tube, and the thermal fluid flows out from the other end, and transfers it to the mixed heat storage medium through the through-tube by convection heat transfer. More specific and practicable heat sources of the heating module and heating methods of the mixed heat storage medium are provided here. In addition, when electric heating is used, the electric heating tube can be directly inserted into the tank body, or the electric heating tube can be inserted into an insertion tube or through-tube and the through-tube or the insertion tube is tightly fitted with the electric heating tube. When thermal fluid heating is used, the through-tube is selected, and the thermal fluid enters from one end of the through-tube and is discharged from the other end. In a preferred embodiment, the heating module is a through-tube, which is convenient for both electric heating and thermal fluid heating, and the same structure can be used to accommodate both heating methods.

[0071] Preferably, the working area of ​​the heat exchanger, the connection area of ​​the heat exchanger, and the tank are connected by flanges in sequence from top to bottom. The flange connection can ensure good connection and communication, and facilitate the passage of heat transfer modules such as heat pipes through the connection, so as to better implement the solution of the present invention and achieve the corresponding purpose.

[0072] Preferably, the interior of the storage tank is filled with a mixed heat storage medium of molten salt and particles in the following manner: the interior of the storage tank is filled with and filled with the particle medium, and the gaps between the particle medium are filled with the molten salt medium to form a mixed heat storage medium of molten salt and particles. A specific feasible filling scheme of the mixed heat storage medium is provided herein.

[0073] The present invention also provides a heat charging and discharging method of the aforementioned single-tank heat storage system, comprising:

[0074] When there is a heat source, the heat source is input to the heat supply module, and the heat storage fluid and the particle mixed medium in the storage tank are gradually heated to the required temperature to complete the heat charging process. During the heat charging stage, no heat extraction medium passes through the heat exchanger.

[0075] During heat extraction, the low-temperature heat extraction medium is introduced into the heat exchanger and absorbs the heat released by the phase change of the phase change working fluid in the part of the heat transfer module in the heat exchanger, thereby increasing in temperature.

[0076] The heat charging and discharging method of the single-tank heat storage system provided by the present invention is suitable for the aforementioned single-tank heat storage system and has good operability.

[0077] In a preferred embodiment, molten salt is selected and electric heating is used as the heat source for heat charging. Using the Joule heating of the electric heating tube, the temperature of the heat supply module is heated to a certain temperature, such as 700 - 800 °C, and natural convective heat transfer occurs with the molten salt medium in the tank. The molten salt then heats the particle medium through direct contact heat transfer, causing the mixed medium in the entire storage tank to gradually rise in temperature to 540 - 565 °C. The present invention provides a specific and operable implementation method here.

[0078] In another preferred embodiment, molten salt is selected and hot gas is used as the heat source for heat charging. The hot gas is continuously input into the heat supply module, and the heat supply module exchanges heat indirectly with the molten salt medium in the tank. The heat transfer method is forced convective heat transfer, and the molten salt then heats the particle medium through direct contact heat transfer. Consequently, the molten salt and particle mixed medium in the entire storage tank gradually rise in temperature to 540 - 565 °C. The present invention provides a specific and operable implementation method here.

[0079] Preferably, during the heat discharging stage, the low-temperature heat extraction medium is introduced into the heat exchanger and absorbs the heat released by the phase change of the phase change working fluid in the part of the heat transfer module in the heat absorber, thereby increasing in temperature. The phase change temperature of the phase change working fluid is in the range of 240 - 260 °C. During the heat discharging process, the part of the heat transfer module in the heat absorber maintains this temperature range. At the same time, the heat extraction medium enters the heat exchanger at a stable temperature and maintains another stable temperature output after heat exchange in the heat exchanger. Among them, a specific example of "the heat exchange medium enters the heat exchanger at a stable temperature and maintains another stable temperature output after heat exchange in the heat exchanger" is: during the heat discharging stage, the low-temperature heat extraction medium is introduced into the heat exchanger and absorbs the heat released by the phase change of the phase change working fluid in the heat release section of the heat pipe, thereby increasing in temperature. The phase change temperature of the phase change working fluid is in the range of 240 - 260 °C. During the heat discharging process, the heat pipe maintains this temperature range, enabling the heat extraction medium to enter at 120 °C at the inlet of the inlet pipe of the heat exchanger. Then, after the heat exchange process in the heat exchanger, the heat extraction medium can be stably maintained at 220 °C for output at the outlet. The present invention provides a specific and operable implementation method here.

[0080] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative work shall fall within the protection scope of the present invention.

[0081] In the description of the present invention, it should be noted that the orientation or positional relationship indicated by the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", etc. is based on the orientation or positional relationship shown in the accompanying drawings. It is only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and thus should not be construed as a limitation to the present invention. In addition, the terms "first", "second", "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0082] In the description of the present invention, it should be noted that unless otherwise clearly specified and defined, the terms "installed", "connected", "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the communication inside two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

[0083] In this article, for the sake of concise description, not all possible combinations of all technical features in each embodiment or example are described. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each embodiment or example can be combined arbitrarily, and all possible combinations should be considered to be within the scope described in this specification.

[0084] Embodiment

[0085] A single-tank heat storage system according to an embodiment of the present invention is as Figure 1A shown.

[0086] The main body of the single-tank heat storage system is a storage tank (1), and a mixed heat storage medium of molten salt and particles, i.e., particle medium (2), is filled inside the storage tank (1). The specific filling method is as follows: the storage tank (1) is filled with and filled with particle medium (2), and molten salt medium is further filled in the gaps of the particle medium (2) to form a filling of the mixed heat storage medium of molten salt and particles.

[0087] Above the main body of the storage tank (1), a heat exchanger (3) is connected by means of flange connection. Moreover, a plurality of heat pipes (4) are arranged in the storage tank (1). The remaining part of each heat pipe (4) except the head is arranged in the storage tank (1) and buried in the mixed heat storage medium of molten salt and particles, in direct contact with the heat storage medium. The head of the heat pipe (4) is located in the heat exchanger (3), and the heat pipe (4) is filled with a phase change working fluid. Alternatively, the connection mode between the storage tank (1) and the heat exchanger (3) can also adopt other conventional modes in the mechanical structure field, as long as the connection between the two can be realized and the communication of the heat pipe at the connection can be ensured.

[0088] The single-tank heat storage system further includes: a plurality of through pipes (5) are inserted into the storage tank (1) from the side wall of the tank body of the storage tank (1), and the through pipes (5) are used to provide heat sources to heat the heat storage medium in the storage tank (1). Alternatively, the plurality of through pipes (5) can also be inserted and penetrate the storage tank (1) from other positions of the tank body of the storage tank (1) except the side wall, as long as the heating of the mixed heat storage medium of molten salt and particles in the storage tank (1) can be realized. The present invention does not limit this. In an alternative embodiment, when the heating method is electric heating, the through pipe can be replaced by an insertion pipe.

[0089] In this embodiment, the arrangement modes of the plurality of through pipes (5) and the plurality of heat pipes (4) are as Figure 1B shown. Among them, the plurality of heat pipes (4) are arranged in a ring shape in the cross-sectional direction and include an inner ring and an outer ring, while the plurality of through pipes (5) are arranged in a layered and cross-shaped manner. Such an arrangement makes the heat pipes and the through pipes evenly distributed and staggered, without conflict. In addition, the arrangement modes of the plurality of through pipes (5) and the plurality of heat pipes (4) can also be other dispersed arrangement modes different from Figure 1B shown, as long as the setting principle of "the plurality of heat pipes are dispersed in the storage tank, the plurality of through pipes are dispersed in the storage tank, and the heat pipes and the through pipes are kept staggered" is satisfied to ensure the uniformity of through pipe heating and heat pipe heat conduction.

[0090] Furthermore, in the single-tank heat storage system described in this embodiment, the preferred structure of the heat pipe (4) is as Figure 3 shown.

[0091] The heat pipe (4) is divided into a heat-releasing section (6), an adiabatic section (7), and a heat-absorbing section (8) from top to bottom. Among them, the heat-releasing section (6) and the adiabatic section (7) belong to the head of the heat pipe (4) and are located inside the heat exchanger (3), and the heat-absorbing section (8) is located inside the storage tank (1) and buried in the mixed heat storage medium of molten salt and particles, being in direct contact with the heat storage medium. When the single-tank heat storage system works, the phase-change working fluid inside the heat pipe (4) absorbs the heat of the mixed heat storage medium of particles and molten salt in the heat-absorbing section (8) and vaporizes, then flows upward, reaches the heat-releasing section (6) after passing through the adiabatic section (7), releases heat through liquefaction in the heat-releasing section (6), and the released heat is transferred to the heat-taking medium inside the heat exchanger (3). The liquefied phase-change working fluid then flows back through the adiabatic section (7) to the heat-absorbing section (8) by gravity to continue absorbing heat, realizing cyclic operation. Correspondingly, in the single-tank heat storage system described in this embodiment, the preferred structure of the heat exchanger (3) is as Figure 4 shown. The heat exchanger (3) is divided into a working area (11) and a connection area (12). And the heat-releasing section (6) of the heat pipe (4) is located inside the working area (11), providing heat as a heat source to the heat-taking medium inside the heat exchanger (3); the adiabatic section (7) is located in the connection area (12) and no heat exchange occurs.

[0092] Preferably, the mixed heat storage medium of particles and molten salt transfers heat to the heat-absorbing section (8) of the heat pipe (4) mainly in the form of heat conduction and natural convection. Therefore, fins (9) are installed on the outer wall of the heat-absorbing section (8). Here, preferably, they are multiple flat fins (9), and they are multiple flat fins (9) evenly arranged circumferentially, used to expand the heat transfer area. For the heat-taking medium inside the heat exchanger (3), it absorbs the energy of the heat-releasing section (6) of the heat pipe (4) in the form of forced convection heat transfer. Therefore, spiral fins (10) are installed on the outer wall of the heat-releasing section (6) to enhance the convective heat transfer coefficient.

[0093] In the heat pipe structure design of this embodiment, the adiabatic section (7) is mainly used to separate the heat-releasing section (6) from the heat-absorbing section (8) and cooperate with the connection area (12) of the heat exchanger (3), so that the heat exchanger (3) ensures that the gasification and liquefaction behaviors of the phase-change working fluid can be clearly separated.

[0094] In this embodiment, from top to bottom, the working area (11), the connection area (12) of the heat exchanger (3), and the tank body of the storage tank (1) are sequentially connected by corresponding flanges (16) to ensure the connection of these three parts and the connection of the heat pipe (4) among them. In addition to flange connection, the present invention can also adopt other replacement methods for connection, as long as the connection of these three parts and the connection of the heat pipe (4) among them are ensured.

[0095] Specifically, in this embodiment, the heat exchanger (3) includes an inlet pipe (13) located at a lower position and an outlet pipe (14) located at a higher position, and two baffles (15) are provided inside the heat exchanger (3). When the heat exchange operation is carried out, the heat-taking medium enters the heat exchanger from the inlet pipe (13), and under the obstruction of the two baffles (15), it undergoes an S-shaped turbulent flow and absorbs the heat released by the heat release section (6) of the heat pipe (4). After heating up, it flows out from the outlet pipe (14). Alternatively, in other embodiments, the number of baffles can be other numbers, such as one, or more than two.

[0096] Specifically, in the single-tank heat storage system described in this embodiment, the heat of the through pipe (5) can be sourced from electric heating or from a hot fluid such as hot air.

[0097] As Figure 2 shown, when electric heating is used as the heat source, the electric heating pipe (17) can be inserted into the through pipe (5) and the two are closely fitted, so that the heat generated by the heating pipe is transferred to the through pipe (5) by conduction, and then the heat storage medium in the storage tank (1) is heated. In an alternative embodiment, an insertion pipe that is inserted into the tank body at one end but is located inside the tank body and does not penetrate out at the other end can be used to replace the through pipe.

[0098] When a hot fluid is used as the heat source, the hot fluid (18) is directly introduced into one end of the through pipe (5) and comes out from the other end, and the heat is transferred to the mixed heat storage medium through the through pipe (5) by means of convective heat transfer.

[0099] Using the single-tank heat storage system of the present invention, the types of the solid particle medium and the molten salt medium can be appropriately selected so that the selected solid particle medium and molten salt medium will not undergo a chemical reaction that has a substantial impact on the stable cyclic operation of the system during long-term operation.

[0100] In addition, preferably in this embodiment, the top of the tank body of the storage tank (1) is made conical, as shown in Figure 1. This can prevent dead zones from appearing in the stacking angle of the particles, thereby maximizing the proportion of particles in the particle and molten salt mixture and achieving a particle volume fraction of 60-63%.

[0101] The embodiment of the present invention also provides a charging and discharging method for the aforementioned single-tank heat storage system, including the following steps:

[0102] When there is a heat source, the heat source is input to a plurality of through pipes (5) inserted into the tank body of the storage tank (1), and the molten salt and particle mixture medium in the storage tank (1) is gradually heated to the required temperature to complete the charging process. During the charging stage, no heat-taking medium will pass through the heat exchanger (3); when taking heat, a low-temperature heat-taking medium is introduced into the heat exchanger (3) to absorb the heat released by the liquefaction of the phase change working medium in the heat release section (6) at the head of the heat pipe (4) in this embodiment and heat up.

[0103] In the single-tank heat storage system of the present invention, since the liquefaction and vaporization temperatures of the phase change working fluid in the heat pipe (4) are basically the same during operation, that is, the whole heat pipe (4) has isothermal property, and the phase change temperature is generally a relatively small interval, the heat pipe (4) always maintains this relatively constant temperature range. Therefore, the heat transfer temperature difference between the heat transfer medium and the heat pipe is also a stable parameter. Furthermore, as long as the input heat extraction medium maintains a stable temperature, it can ensure that the outlet temperature of the heat extraction medium when leaving the heat exchanger is also a relatively stable value, which is very friendly to the power equipment at the back end of the system. At the same time, the charging and discharging of the single-tank heat storage system of the present invention can be carried out simultaneously. For example, the abandoned photovoltaic power during the day and the valley electricity or abandoned wind power at night can be used to maintain long-term charging. Even if the temperature in the tank is uneven, it will not affect the temperature during the discharging section.

[0104] The following provides two application examples of the single-tank heat storage system of the present invention.

[0105] Application Example 1

[0106] In this example, electric heating is used as the heat source to charge the single-tank heat storage system of the above embodiment.

[0107] During the charging process, during the period of abandoned photovoltaic and wind power or valley electricity at night, the Joule heat of the electric heating tube is utilized to first conduct heat to the through pipe (5), so that the temperature of the through pipe (5) is heated to 700 - 800 °C, and natural convective heat transfer occurs with the molten salt medium in the tank. The molten salt then heats the particulate medium through direct contact heat transfer. Therefore, the mixed medium in the entire storage tank is gradually heated to 540 - 565 °C, and the phase change working fluid in the heat pipe (4) absorbs heat and vaporizes in the heat absorption section (8) and flows upward.

[0108] During the exothermic stage, a low-temperature heat extraction medium with a relatively constant temperature is introduced into the heat exchanger (3). The low-temperature heat extraction medium absorbs the heat released by the liquefaction of the phase-change working fluid in the heat release section (6) of the heat pipe (4) and thus its temperature rises. Since the liquefaction and vaporization temperatures of the phase-change working fluid in the heat pipe (4) are basically the same during operation, that is, the entire heat pipe (4) has isothermal properties, then during the exothermic process, the heat pipe (4) will be maintained at this temperature range. Furthermore, the temperature of the heat extraction medium will become relatively controllable during the entire heating process. For example, if the phase-change temperature of the selected phase-change working fluid is in the range of 240 - 260 °C, and the heat extraction medium enters at 120 °C at the inlet of the inlet pipe of the heat exchanger (3), then during the exothermic process, the heat pipe (4) will be maintained at the temperature range of 240 - 260 °C, keeping the heat transfer temperature difference between the heat extraction medium and the heat pipe (4) stable. Furthermore, the temperature of the heat extraction medium will become relatively controllable during the entire heating process, and the heat extraction medium after heat transfer can be stably maintained at 220 °C and output at the outlet of the outlet pipe of the heat exchanger (3). As the exothermic process continues, the overall temperature in the storage tank will gradually decrease from 565 °C to 320 °C. Therefore, the heat absorption temperature difference between the heat pipe and the mixed medium in the storage tank will gradually become smaller, and the circulation rate of the phase-change working fluid in the heat pipe will gradually decrease, but its operating temperature will be stable at 240 - 260 °C. Therefore, only by gradually reducing the flow rate of the heat extraction medium, that is, reducing the exothermic power, as the exothermic process continues. As the exothermic process progresses, finally the overall temperature of the storage tank can be reduced to around 290 - 310 °C. Thus, the entire charging and discharging cycle is completed.

[0109] Application Example 2

[0110] In this example, hot gas is used as the heat source to charge the single-tank heat storage system of the above embodiment, and the heat of the hot air can come from blast furnace slag waste heat, boiler flue gas, etc.

[0111] During the charging process, hot gas is continuously input into the through pipe (5). Indirect heat transfer occurs between the heat-conducting material wall of the through pipe (5), such as a metal pipe wall, and the molten salt medium in the storage tank (1) through forced convection heat transfer. The molten salt medium then heats the particulate medium through direct contact heat transfer. Therefore, the mixed medium in the entire storage tank (1) is gradually heated to 540 - 565 °C, and the gas after heat release can be recycled.

[0112] During the exothermic stage, a low-temperature heat extraction medium with a relatively constant temperature is introduced into the heat exchanger (3). The low-temperature heat extraction medium absorbs the heat released by the liquefaction of the phase-change working fluid in the exothermic section (6) of the heat pipe (4) and heats up. Since the liquefaction and vaporization temperatures of the phase-change working fluid in the heat pipe (4) are basically the same during operation, that is, the whole heat pipe (4) has isothermal properties, then during the exothermic process, the heat pipe (4) will maintain at this temperature range. Furthermore, the temperature of the heat extraction medium will become relatively controllable during the entire heating-up process. For example, if the phase-change temperature of the selected phase-change working fluid is in the range of 240 - 260 °C, and the heat exchange medium enters at 120 °C at the inlet of the inlet pipe of the heat exchanger (3), then during the exothermic process, the heat pipe (4) will maintain at the temperature range of 240 - 260 °C, keeping the heat exchange temperature difference between the heat extraction medium and the heat pipe (4) stable. Furthermore, the temperature of the heat extraction medium will become relatively controllable during the entire heating-up process, and the heat extraction medium after heat exchange can be stably maintained at 220 °C and output at the outlet of the outlet pipe of the heat exchanger (3). As the exothermic process continues, the overall temperature in the storage tank will gradually decrease from 565 °C to 320 °C. Therefore, the heat absorption temperature difference between the heat pipe and the mixed medium in the storage tank will gradually become smaller, and the circulation rate of the phase-change working fluid in the heat pipe will gradually decrease, but its working temperature will be stable at 240 - 260 °C. Therefore, only by gradually reducing the flow rate of the heat extraction medium, that is, reducing the exothermic power, as the exothermic process continues. As the exothermic process progresses, finally the overall temperature of the storage tank can be reduced to about 290 - 310 °C. Thus, the entire charge-discharge cycle is completed.

[0113] Compared with the prior art, the single-tank heat storage system provided by the present invention and the above embodiments and application examples has the following advantages:

[0114] 1. It realizes the hybrid heat storage of particles and molten salt, combines the characteristics of low-cost particles and good heat transfer properties of molten salt, and is different from the mode in the traditional double-tank system where molten salt needs to be continuously introduced into and discharged from the storage tank. Therefore, it will not cause the molten salt to carry particle impurities and affect the subsequent equipment.

[0115] 2. Compared with the existing single-tank system, in the single-tank heat storage system of the present invention, the storage tank utilizes the characteristics of the phase-change working fluid in the heat pipe to keep the temperature difference at the heat exchange end of the heat exchanger constant during heat extraction, which is beneficial to the operation of the subsequent power equipment; at the same time, heat charging and heat discharging can be carried out simultaneously, such as the abandoned photovoltaic power during the day and the valley electricity or abandoned wind power at night, and long-term heat charging can be maintained. Even if the temperature in the tank is uneven, it will not affect the temperature of the exothermic section.

[0116] 3. Different from the double-tank system that needs to consider taking out the molten salt, and also different from the single-tank storage tank that needs to consider increasing the height to ensure the proportion of the thermocline, this single-tank heat storage system can make the height-diameter ratio smaller, that is, the appearance is short and fat. On the one hand, this can reduce the cost of the ground foundation, and on the other hand, it can reduce the heat dissipation of the tank body.

[0117] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some or all of the technical features; and these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the various embodiments of the present invention. The present invention is only limited by the claims and their full scope and equivalents.

Claims

1. A single-tank heat storage system, characterized in that, Comprising: A storage tank, the interior of which is filled with a heat storage medium that is a mixture of a heat storage fluid and particles; A heat exchanger, which is arranged outside the storage tank; A plurality of heat transfer modules, which are filled with a phase change working fluid. A part of each heat transfer module is located inside the heat exchanger and is in heat transfer contact with the heat transfer medium inside the heat exchanger. At least a part of the heat transfer module located outside the heat exchanger is located inside the storage tank and is buried in the mixed heat storage medium and is in heat transfer contact with the mixed heat storage medium; A plurality of heat supply modules, which include a part located inside the storage tank and providing a heat source to heat the mixed heat storage medium inside the storage tank; and, A plurality of the heat transfer modules are dispersedly arranged inside the storage tank, a plurality of the heat supply modules are dispersedly arranged inside the storage tank, and the heat transfer modules and the heat supply modules are kept staggered.

2. The single-tank heat storage system according to claim 1, wherein The heat exchanger is located above the storage tank.

3. The single-tank heat storage system according to claim 1 or 2, characterized in that, The heat transfer module is a heat pipe, the head of which is located inside the heat exchanger, and at least a part of the part outside the head of the heat pipe is located inside the storage tank and is buried in the mixed heat storage medium and is in heat transfer contact with the mixed heat storage medium.

4. The single-tank heat storage system according to claim 3, characterized in that, The heat pipe includes a heat release section and a heat absorption section from top to bottom. The heat release section is located inside the heat exchanger, and the heat absorption section is located inside the storage tank. During operation, the phase change working fluid inside the heat pipe absorbs the heat of the mixed heat storage medium in the heat absorption section, vaporizes, then flows upward to the heat release section, releases heat through liquefaction, and transfers it to the heat extraction medium inside the heat exchanger. The liquefied phase change working fluid then flows back to the heat absorption section to continue absorbing heat, realizing cyclic operation; correspondingly, the heat exchanger includes a working area, and the heat release section of the heat pipe is located in the working area of the heat exchanger.

5. The single-tank heat storage system according to claim 4, wherein, The heat pipe further includes an adiabatic section located between the heat release section and the heat absorption section. The heat release section and the adiabatic section form the head of the heat pipe and are located inside the heat exchanger; the adiabatic section separates the heat release section from the heat absorption section and ensures that the vaporization and liquefaction behaviors of the phase change working fluid can be separated; correspondingly, the heat exchanger includes a connection area, and the working area of the heat exchanger, the connection area of the heat exchanger, and the tank body are connected in sequence from top to bottom; wherein, the adiabatic section of the heat pipe is located in the connection area of the heat exchanger and no heat exchange occurs.

6. The single-tank heat storage system according to claim 4, characterized in that, The heat absorption section of the heat pipe is provided with a first component for expanding the heat transfer area.

7. The single-tank heat storage system according to claim 4, characterized in that, The heat release section of the heat pipe is provided with a second component for enhancing the convective heat transfer coefficient.

8. The single-tank heat storage system according to claim 6, wherein, The first component for expanding the heat transfer area of the heat absorption section of the heat pipe is a plurality of flat fins, and the plurality of flat fins are uniformly arranged along the circumferential direction of the heat pipe.

9. The single-tank heat storage system according to claim 7, wherein The second component for enhancing the convective heat transfer coefficient of the heat release section of the heat pipe is a spiral fin.

10. The single-tank heat storage system according to claim 3, characterized in that, The heat supply module includes a plurality of insertion pipes or through pipes inserted into the storage tank, and a heat providing unit is included inside the insertion pipes or through pipes.

11. The single-tank heat storage system according to claim 10, characterized in that, A plurality of the insertion pipes or through pipes are inserted into the storage tank from the side wall of the tank body of the storage tank, and a plurality of the insertion pipes or through pipes are arranged in layers inside the storage tank.

12. The single-tank heat storage system according to claim 11, wherein, The cross-sections of multiple said heat pipes are arranged in a ring shape within the tank, and are arranged in one or multiple concentric circles. Multiple said insertion pipes or through pipes are arranged in a layered and crosswise manner within the storage tank, and the heat pipes and the insertion pipes or through pipes are evenly dispersed and staggered.

13. The single-tank heat storage system according to claim 1, characterized in that, The heat exchanger includes an inlet pipe located at a lower position and an outlet pipe located at a higher position, and several baffle plates are provided within the heat exchanger. When the heat exchange operation is carried out, the heat-taking medium enters the heat exchanger from the inlet pipe, and under the obstruction of the baffle plates, it undergoes turbulent flow and absorbs heat, and then flows out from the outlet pipe after temperature rise.

14. The single-tank heat storage system according to claim 1, characterized in that, The height-diameter ratio of the storage tank is less than or equal to 2.

15. The single-tank heat storage system according to claim 1, characterized in that, The top of the tank body of the storage tank is conical.

16. The single-tank heat storage system according to claim 10, characterized in that, The heat source of the insertion pipe or through pipe is electric heating or a heat fluid. When electric heating is used as the heat source, the insertion pipe or through pipe is an electric heating pipe, or an electric heating pipe is inserted into the insertion pipe or through pipe and the insertion pipe or through pipe is in close contact with the electric heating pipe; when a heat fluid is used as the heat source, the heat fluid is directly introduced into one end of the through pipe, and the heat fluid flows out from the other end, and the heat is transferred to the mixed heat storage medium through the through pipe by means of convective heat transfer.

17. A method for charging and discharging heat of the single-tank heat storage system according to any one of claims 1-16, characterized in that, Including: When there is a heat source, the heat source is input to the heat supply module, and the mixed medium in the storage tank is gradually heated to the required temperature to complete the heat charging process. During the heat charging stage, no heat-taking medium passes through the heat exchanger. When taking heat, the low-temperature heat-taking medium is introduced into the heat exchanger and absorbs the heat released by the liquefaction of the phase-change working fluid in a part of the heat transfer module within the heat exchanger to increase in temperature.

18. The charging and discharging method of the single-tank heat storage system according to claim 17, characterized in that, When using electric heating as the heat source for heat charging, the Joule heating of the electric heating pipe is utilized to heat the temperature of the heat supply module, and heat transfer occurs with the heat storage fluid medium in the tank. The heat storage fluid in turn heats the granular medium through direct contact heat transfer, so that the mixed heat storage medium in the entire storage tank is gradually heated to 540 - 565 °C.

19. The charging and discharging method of the single-tank heat storage system according to claim 17, characterized in that, When using hot gas as the heat source for heat charging, the hot gas is input to the heat supply module, and the heat supply module undergoes indirect heat exchange with the heat storage fluid medium in the tank. The heat storage fluid medium in turn heats the granular medium through direct contact heat transfer, and thus the mixed heat storage medium in the entire storage tank is gradually heated to 540 - 565 °C.

20. The charging and discharging method of the single-tank heat storage system according to claim 17, characterized in that, During the heat release stage, the low-temperature heat-taking medium is introduced into the heat exchanger and absorbs the heat released by the liquefaction of the phase-change working fluid in a part of the heat transfer module located within the heat absorber to increase in temperature. The phase-change temperature of the phase-change working fluid is in the range of 240 - 260 °C. During the heat release process, the part of the heat transfer module within the heat exchanger is maintained at this temperature range. At the same time, the heat-taking medium enters the heat exchanger at a stable temperature and maintains another stable temperature output after heat exchange in the heat exchanger.

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