Heat storage tank applied to solar heating system and preparation method of high-thermal-conductivity composite phase change material
By using high thermal conductivity composite phase change materials and special heat storage tank designs in solar heating systems, the problems of poor thermal conductivity and low heat storage density in the existing system are solved, and more efficient heat energy conduction and storage are achieved.
Patent Information
- Application Number
- CN202411274974.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-12
- Publication Date
- 2025-01-21
AI Technical Summary
In existing solar heating systems, the thermal conductivity and low heat storage density of the heat storage materials lead to low thermal conductivity efficiency, limiting the compact design and efficient thermal energy utilization of the system.
By selecting appropriate high thermal conductivity adsorption materials and combining them with phase change materials, high thermal conductivity composite phase change materials are prepared, and a special internal structure of the heat storage tank is designed, including double-layer spiral wound tubes and multiple heat exchange pipes, to improve heat transfer efficiency.
It significantly improves the heat exchange rate and heat storage efficiency of the heat storage tank, meets the demand for efficient thermal energy utilization, and improves the overall performance and stability of the system.
Smart Images
Figure CN119333982A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of thermal energy storage, and in particular relates to a heat storage tank applied to a solar heating system and a method for preparing a high thermal conductivity composite phase change material. Background Art
[0002] With the continuous growth of energy demand and the improvement of environmental protection awareness, solar energy, as a clean and renewable energy, has received more and more attention and application. Solar heating systems use solar energy as the main energy source, convert solar energy into thermal energy through collectors and store it for release when needed. In existing solar heating systems, the commonly used heat storage methods mainly rely on sensible heat storage materials such as water or sand and gravel. These materials have the problems of low heat storage density and large system volume, which leads to limitations in compact design and efficient thermal energy utilization.
[0003] Phase change materials (PCM) are gradually being used in thermal storage systems because of their high heat storage density and constant temperature heat release. Phase change materials undergo a phase change process (such as solid-liquid phase change) when absorbing or releasing heat, storing and releasing a large amount of thermal energy within a small temperature range, thereby significantly improving the performance of the thermal storage system. However, the thermal conductivity of the phase change material itself is poor, which limits its thermal conduction efficiency in practical applications.
[0004] In the current technical solution, a high thermal conductivity adsorption material is compounded with a phase change material to form a high thermal conductivity composite phase change material (CPCM) to improve its thermal conductivity. At the same time, in order to ensure that heat can be evenly and efficiently conducted during storage and release, the design of the heat storage tank also needs to be optimized. However, the existing technology still has many technical problems and practical application obstacles in terms of the selection of high thermal conductivity composite phase change materials, compounding process, and internal structure design of heat storage tanks. Summary of the invention
[0005] The purpose of the present invention is to provide a heat storage tank and a method for preparing a high thermal conductivity composite phase change material for use in a solar heating system. The heat storage tank selects a more suitable high thermal conductivity adsorption material and a phase change material for composite preparation to synthesize a high thermal conductivity composite phase change material, and through a special internal structure design of the heat storage tank, the heat storage efficiency and the overall performance of the system are significantly improved to solve the problems of poor thermal conductivity and low heat storage density in the prior art. Through the implementation of the present invention, the solar heating system can be made to operate more efficiently and stably, and the requirements of the growing energy demand and environmental protection can be met.
[0006] To achieve the above-mentioned object, the present invention provides a high thermal conductivity composite phase change filled heat storage tank applied to a solar heating system, comprising a tank body, a horizontal heat exchange top plate is fixedly provided at the upper end of the tank body, a horizontal heat exchange bottom plate is fixedly provided at the lower end of the tank body, a heat storage bin is provided between the heat exchange top plate and the heat exchange bottom plate, and a plurality of heat exchange pipes are provided in the heat storage bin;
[0007] The heat storage bin is filled with a high thermal conductivity composite phase change material;
[0008] The top end of the tank body is fixedly provided with a heat exchange medium inlet, and the bottom end of the tank body is fixedly provided with a heat exchange medium outlet;
[0009] A plurality of support frames are fixedly provided at the lower end of the side wall of the tank body.
[0010] Furthermore, there are two heat exchange medium inlets, which are arranged oppositely at the top end of the tank body, and there are two heat exchange medium outlets, which are arranged oppositely at the bottom end of the tank body.
[0011] Furthermore, a first heat medium buffer bin is provided between the upper end of the heat exchange top plate and the inner part of the tank body, and a second heat medium buffer bin is provided between the lower end of the heat exchange bottom plate and the inner part of the tank body.
[0012] Furthermore, the heat exchange medium inlet connects the first heat medium buffer bin with the outside of the tank body, and the heat exchange medium outlet connects the second heat medium buffer bin with the outside of the tank body.
[0013] Furthermore, the heat exchange pipe includes a plurality of inner circle bends and outer circle bends, and the inner circle bends and the outer circle bends are staggered and equidistantly spirally wound from the inside to the outside, and the spiral directions of the inner circle bends and the outer circle bends are opposite.
[0014] Furthermore, the shell of the tank body consists of an outer wall, an insulation layer and an inner wall, and the insulation material used in the insulation layer is at least one of polyurethane foam, glass wool, aerogel felt, aluminum silicate wool and rock wool.
[0015] Furthermore, there are three support frames in total, the top ends of the support frames are equidistantly fixed on the side walls of the bottom of the tank body, the bottoms of the support frames are fixedly connected to the ground, and the three support frames are equidistantly arranged in an equilateral triangle.
[0016] A method for preparing a high thermal conductivity composite phase change material, the specific steps are as follows:
[0017] S1: Weigh the phase change material and the high thermal conductivity adsorption material, heat them together to above the phase change temperature of the phase change material, until the phase change material is completely melted into a liquid state, and stir at a constant speed for 10 minutes;
[0018] S2: placing the mixture in a pressure tank, setting the working temperature to be higher than the phase change temperature of the phase change material, and pumping the pressure tank to a vacuum degree of 100 kPa by a vacuum drying pump, and maintaining the vacuum for 5 minutes;
[0019] S3: Increase the pressure in the pressure tank to 1Mpa through the gas booster pump and maintain it for 5 minutes;
[0020] S4: Stop heating, and gradually cool the mixture until the phase change material is completely solidified to obtain a high thermal conductivity composite phase change material.
[0021] The present invention provides a high thermal conductivity composite phase change filled heat storage tank applied to a solar heating system, which reduces the overall volume of the system while ensuring structural stability, effectively improving the utilization rate of space. The use of high thermal conductivity composite phase change materials and double-layer spirally wound pipes greatly improves the heat exchange rate of the heat storage tank, enables rapid and uniform transfer of thermal energy, improves the efficiency of heat storage and release, and meets the demand for efficient thermal energy utilization.
[0022] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS
[0023] Figure 1 It is a schematic diagram of the structure of the present invention.
[0024] Figure 2 It is a schematic top view of the top plate of the heat exchange pipe of the present invention.
[0025] Figure 3 It is a schematic diagram of the tank structure of the present invention.
[0026] Explanation of the accompanying drawings: 1. tank body; 101. outer wall; 102. insulation layer; 103. inner wall; 2. heat exchange top plate; 3. heat exchange bottom plate; 4. heat storage bin; 5. heat exchange pipe; 501. inner circle elbow; 502. outer circle elbow; 6. high thermal conductivity composite phase change material; 7. heat exchange medium inlet; 8. heat exchange medium outlet; 9. support frame; 10. first heat medium buffer bin; 11. second heat medium buffer bin. DETAILED DESCRIPTION
[0027] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined purpose, the specific implementation methods, structural features and effects of the present invention are described in detail below in conjunction with the accompanying drawings and embodiments.
[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.
[0029] In the description of the present invention, it is necessary to understand that the terms "center", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "aligned", "overlap", "bottom", "inside", "outside" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.
[0030] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of the present invention, unless otherwise specified, "plurality" means two or more.
[0031] Example 1
[0032] This embodiment provides Figure 1 to Figure 3 A high thermal conductivity composite phase change filled heat storage tank used in a solar heating system is shown, comprising a tank body 1, a horizontal heat exchange top plate 2 is fixedly arranged at the upper end of the tank body 1, a horizontal heat exchange bottom plate 3 is fixedly arranged at the lower end of the tank body 1, a heat storage bin 4 is arranged between the heat exchange top plate 2 and the heat exchange bottom plate 3, a plurality of heat exchange pipes 5 are arranged in the heat storage bin 4, and the material used for the tank body 1 is 304 stainless steel, which has more superior anti-corrosion and wear-resistant properties while ensuring the overall stability of the heat storage tank structure. The interior of the tank body 1 includes a heat exchange top plate 2, a heat storage bin 4, and a heat exchange bottom plate 3 from top to bottom. The heat storage bin 4 is a cylindrical cavity formed in the middle of the tank body 1 after the heat exchange top plate 2 and the heat exchange bottom plate 4 separate the tank body 1. A heat exchange pipe 5 is arranged inside the heat storage bin 4. The heat exchange medium exchanges heat in the heat exchange pipe 5. The heat exchange pipe 5 is made of copper material as a whole. The superior thermal conductivity and anti-corrosion properties of copper material greatly improve the heat exchange efficiency and also significantly improve the life of the heat exchange pipe 5.
[0033] The interior of the heat storage bin 4 is also filled with a high thermal conductivity composite phase change material 6, which fills the gap between the heat exchange pipe 5 and the heat storage bin 4, ensuring that the heat exchange medium can better exchange heat stored in the high thermal conductivity composite phase change material 6 during the flow of the heat exchange pipe 5;
[0034] A heat exchange medium inlet 7 is fixedly provided at the top of the tank body 1, and a heat exchange medium inlet 7 is fixedly provided at the bottom of the tank body 1. The specific heat exchange medium passes through the heat exchange medium inlet 7;
[0035] A plurality of support frames 9 are fixedly provided at the lower end of the side wall of the tank body 1 , and the support frames 9 are used to support and fix the entire tank body 1 and increase its stability.
[0036] Further, such as Figure 1 As shown, two heat exchange medium inlets 7 are provided and are relatively arranged at the top of the tank body 1, and two heat exchange medium inlets 7 are also provided and are relatively arranged at the bottom of the tank body 1. The two heat exchange medium inlets 7 are relatively arranged at the top of the tank body 1, and the heat exchange medium can be added together during use to improve the overall heat exchange efficiency of the heat storage tank. Similarly, two heat exchange medium inlets 7 are relatively arranged at the bottom of the tank body 1, so that the discharge of the heat exchange medium is more efficient, and the overall heat exchange medium pressure inside the heat storage tank is more stable, and the operation is smoother.
[0037] Furthermore, a first heat medium buffer bin 10 is provided between the upper end of the heat exchange top plate 2 and the inside of the tank body 1 , and a second heat medium buffer bin 11 is provided between the lower end of the heat exchange bottom plate 3 and the inside of the tank body 1 .
[0038] Furthermore, the heat exchange medium inlet 7 connects the first heat medium buffer bin 10 with the outside of the tank body 1 , and the heat exchange medium outlet 8 connects the second heat medium buffer bin 11 with the outside of the tank body 1 .
[0039] Specifically, the arrangement of the heat exchange top plate 2 forms an additional semi-elliptical cavity with the upper end of the tank body 1: the first heat medium buffer bin 10. When the heat exchange medium is injected, the heat exchange medium flows into the first heat medium buffer bin 10 from the heat exchange medium inlet 7, so that the heat exchange medium can flow into the heat exchange pipe 5 more evenly and uniformly; the heat exchange bottom plate 3 and the tank body 1 form a second heat medium buffer bin 11. When the heat exchange medium flows out of the heat exchange pipe 5, it will fill the second heat medium buffer bin 11, and then flow out of the tank body 1 through the heat exchange medium outlet 8, finally ensuring the balance of the liquid pressure in the heat storage tank, controlling the flow rate of the heat exchange medium not to be too fast, so that the heat exchange medium can be more fully heat exchanged in the heat storage tank;
[0040] The heat exchange medium inlet 7 and the heat exchange medium outlet 8 are both connected to the external pipes through flanges. The use of flanges can achieve better airtightness and higher connection strength, which can avoid the heat exchange medium from flowing out of the connection to cause waste of resources, and further ensure the overall internal pressure of the heat storage tank, making the heat exchange process more stable and smooth.
[0041] Further, such as Figure 2As shown, the heat exchange pipe 5 includes a plurality of inner bends 501 and outer bends 502, the inner bends 501 and the outer bends 502 are staggered and equidistantly spirally wound from the inside to the outside, and the spiral directions of the inner bends 501 and the outer bends 502 are opposite;
[0042] Eight heat exchange pipes 5 are arranged in the heat storage bin 4, including four outer ring bent pipes 502 staggered and equidistantly wound in a clockwise spiral, and four inner ring bent pipes 501 staggered and equidistantly wound in a clockwise spiral. The heat exchange inlet of the inner ring bent pipe 501 is located at the quarter point of the inner circle of the heat exchange top plate 2, and the pipe mouth is welded to the heat exchange top plate 2. The four inner ring bent pipes 501 form an inner ring heat exchange pipe layer, and the heat exchange inlet of the outer ring bent pipe 502 is located at the quarter point of the outer circle of the heat exchange top plate 2. The four outer ring bent pipes 502 form an outer ring heat exchange pipe layer. By arranging the heat exchange pipes 5 at the quarter points of the inner and outer circles, the overall force of the heat exchange pipes 5 can be made more uniform, the stress concentration of the heat exchange pipes 5 caused by thermal expansion and contraction or fluid pressure changes can be reduced, and the overall structural stability of the system can be improved. The inner and outer ring heat exchange pipe layers are respectively wound in a clockwise and counterclockwise spiral, which reduces dead corners and invalid spaces, increases the path length of the fluid in the heat exchange pipe, and thus improves the compactness and efficiency of the equipment.
[0043] The double-layer spirally wound tube makes the contact area between the heat exchange medium and the high thermal conductivity composite phase change material 6 in the heat exchange pipe 5 larger, which greatly improves the heat exchange rate of the heat storage tank. The equidistant arrangement of the spirals allows the heat exchange medium to flow at a uniform speed in the heat exchange pipe 5, avoiding the acceleration from exerting a large impact force on the heat exchange pipe 5, causing impact on the heat storage tank as a whole, affecting the heat exchange efficiency and damaging the structure.
[0044] Furthermore, the shell of the tank body 1 is composed of an outer wall 101, an insulation layer 102 and an inner wall 103. The insulation material used in the insulation layer 102 includes at least one of polyurethane foam, glass wool, aerogel felt, aluminum silicate wool and rock wool. The insulation layer 102 is formed by filling the insulation material between the outer wall 101 and the inner wall 103 of the tank body 1, which can further retain the temperature inside the tank body 1 so that it will not overflow and cause temperature loss.
[0045] Furthermore, there are three support frames 9, the top ends of the three support frames 9 are equidistantly fixed on the side walls of the bottom of the tank body 1, and the bottoms of the support frames 9 are fixedly connected to the ground. The three support frames 9 are equidistantly arranged around the tank body 1 in an equilateral triangle. Since the heat exchange medium flows spirally in the tank body 1, the support frames 9 are arranged to fix the entire tank body 1 to the ground to stabilize the entire tank body 1 so that it will not shake due to force. The triangular arrangement allows the support frames 9 to bring the most stable supporting force and can also offset the lateral impact force of the heat exchange medium on the tank body 1 in the lateral direction, making the heat exchange process smoother and more reliable.
[0046] Specifically, the high thermal conductivity composite phase change material 6 is prepared by compounding a phase change material and a high thermal conductivity adsorption material. The new material high thermal conductivity composite phase change material 6 has both the excellent thermal conductivity of the high thermal conductivity adsorption material and the high heat storage and high energy storage characteristics of the phase change material.
[0047] The materials used in the phase change material are one or more of paraffin, stearic acid, lauric acid or capric acid;
[0048] The material used for the high thermal conductivity adsorption material is one or more of expanded graphite and carbon nanotubes;
[0049] A method for preparing a high thermal conductivity composite phase change material, the specific steps are as follows:
[0050] S1: First weigh a certain amount of phase change material and high thermal conductivity adsorption material, heat the two together to above the phase change temperature of the phase change material, until the phase change material is completely melted into a liquid to form a mixture, and then stir the mixture at a constant speed for 10 minutes;
[0051] S2: Place the mixture in a pressure tank, set the working temperature of the pressure tank, which needs to be higher than the phase change temperature of the phase change material, and extract the air in the pressure tank through a vacuum drying pump until the pressure reaches a vacuum degree of 100 kPa, and then maintain it for 5 minutes;
[0052] S3: The pressure tank is pressurized by a gas booster pump. When the pressure reaches the normal pressure state, that is, the air pressure is 1Mpa, it is maintained for 5 minutes;
[0053] S4; stop heating, the mixture will gradually cool down, and after the phase change material in the mixture is completely solidified, a high thermal conductivity composite phase change material 6 can be obtained.
[0054] When in use: the heat exchange medium is injected into the tank body 1 through the heat exchange medium inlet 7. After flowing into the first heat medium buffer bin 10, the heat exchange medium flows evenly and smoothly into the double-layer spirally wound heat exchange pipe 5. In the heat storage bin 4, the heat exchange medium absorbs the heat stored in the surrounding high thermal conductivity composite phase change material 6 in the heat exchange pipe 5 and flows at a uniform speed until it flows into the second heat medium buffer bin 11 and finally flows out of the tank body 1 through the heat exchange medium outlet 8, completing the entire heat exchange process;
[0055] During heat exchange, the heat exchange medium is injected into the tank body 1 from the heat exchange medium inlet 7. Due to the setting of the double-layer spirally wound heat exchange pipe 5, the travel of the heat exchange medium in the heat storage tank is lengthened in a limited space, and the heat exchange time with the high thermal conductivity composite phase change material 6 is improved. Therefore, the heat stored in the high thermal conductivity composite phase change material 6 in the heat storage tank can be fully absorbed. When heat energy needs to be released, the valve at the heat exchange medium outlet 8 port is opened, and the heat exchange medium can carry the stored heat and transfer it to the external system.
[0056] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the protection scope of the present invention.
Claims
1. A heat storage tank for a solar heating system, comprising a tank body (1), characterized in that: A horizontal heat exchange top plate (2) is fixedly provided at the upper end of the tank body (1), a horizontal heat exchange bottom plate (3) is fixedly provided at the lower end of the tank body (1), a heat storage bin (4) is provided between the heat exchange top plate (2) and the heat exchange bottom plate (3), and a plurality of heat exchange pipes (5) are provided in the heat storage bin (4); The heat storage bin (4) is filled with a high thermal conductivity composite phase change material (6); A heat exchange medium inlet (7) is fixedly provided at the top end of the tank body (1), and a heat exchange medium outlet (8) is fixedly provided at the bottom end of the tank body (1); A plurality of support frames (9) are fixedly provided at the lower end of the side wall of the tank body (1).
2. A heat storage tank for a solar heating system as claimed in claim 1, characterized in that: There are two heat exchange medium inlets (7) arranged opposite to each other at the top end of the tank body (1), and there are two heat exchange medium outlets (8) arranged opposite to each other at the bottom end of the tank body (1).
3. A heat storage tank for a solar heating system as claimed in claim 2, characterized in that: A first heat medium buffer bin (10) is provided between the heat exchange top plate (2) and the upper end of the tank body (1), and a second heat medium buffer bin (11) is provided between the heat exchange bottom plate (3) and the lower end of the tank body (1).
4. A heat storage tank for a solar heating system as claimed in claim 3, characterized in that: The heat exchange medium inlet (7) connects the first heat medium buffer bin (10) with the outside of the tank body (1), and the heat exchange medium outlet (8) connects the second heat medium buffer bin (11) with the outside of the tank body (1).
5. The heat storage tank used in a solar heating system according to claim 1, characterized in that: The heat exchange pipe (5) comprises a plurality of inner circle curved pipes (501) and outer circle curved pipes (502), wherein the inner circle curved pipes (501) and the outer circle curved pipes (502) are staggered and equidistantly spirally wound from the inside to the outside, and the spiral directions of the inner circle curved pipes (501) and the outer circle curved pipes (502) are opposite.
6. The heat storage tank used in a solar heating system according to claim 1, characterized in that: The shell of the tank body (1) is composed of an outer wall (101), a thermal insulation layer (102) and an inner wall (103); the thermal insulation material used in the thermal insulation layer (102) is at least one of polyurethane foam, glass wool, aerogel felt, aluminum silicate wool and rock wool.
7. The heat storage tank used in a solar heating system according to claim 1, characterized in that: There are three support frames (9) in total, the top ends of the support frames (9) are fixedly arranged at equal distances on the side wall of the bottom of the tank body (1), the bottoms of the support frames (9) are fixedly connected to the ground, and the three support frames (9) are arranged at equal distances in the form of an equilateral triangle.
8. A method for preparing a high thermal conductivity composite phase change material, characterized in that: The specific steps are as follows: S1: Weigh the phase change material and the high thermal conductivity adsorption material, heat them together to above the phase change temperature of the phase change material, until the phase change material is completely melted into a liquid state, and stir at a constant speed for 10 minutes; S2: placing the mixture in a pressure tank, setting the working temperature to be higher than the phase change temperature of the phase change material, and pumping the pressure tank to a vacuum degree of 100 kPa by a vacuum drying pump, and maintaining the vacuum for 5 minutes; S3: Increase the pressure in the pressure tank to 1Mpa through the gas booster pump and maintain it for 5 minutes; S4; stop heating, and gradually cool the mixture until the phase change material is completely solidified, thereby obtaining a high thermal conductivity composite phase change material (6).