Fin type U-shaped buried pipe heat accumulator matched with solar heat storage
By using U-shaped finned pipes in the buried pipe heat storage device, the solar heat is transferred to the phase change backfill material, which solves the problem of low heat exchange performance of the buried pipe heat storage device and realizes efficient solar heat storage and heat release process.
Patent Information
- Application Number
- CN202422142270.8
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-02
- Publication Date
- 2025-06-17
- Estimated Expiration
- 2034-09-02
AI Technical Summary
The heat exchange performance of buried pipe heat storage devices is low, resulting in a long heat storage time and low heat storage efficiency when combined with solar energy.
U-shaped finned pipelines are used to transfer heat energy in solar high-temperature hot fluid to phase change backfill material in the shaft, and the heat exchange area and fluid disturbance are increased through the U-shaped finned structure to improve heat storage efficiency.
The efficient heat storage and heat release process for solar heat is achieved, the heat storage efficiency of solar heat storage is improved, and the efficient heat exchange between cold and hot fluids and solid-liquid phase change backfilling materials is achieved.
Smart Images
Figure CN222993215U_ABST
Abstract
Description
Technical Field
[0001] The utility model relates to the technical field of heat storage devices, in particular to a finned U-shaped buried pipe heat accumulator combined with solar heat storage. Background Art
[0002] The energy problem is an important factor restricting social development, and the concept of green, healthy and sustainable development has gradually entered the public's vision. The excessive use of traditional fossil fuels has caused a large amount of greenhouse gas emissions. The rise and development of renewable energy are of great significance for the structural transformation, kinetic energy transformation and low-carbon transformation in China. Solar energy is an environmentally friendly and clean energy source and a potential candidate to meet the global energy demand. As an effective means to solve the contradiction between energy supply time and space, the phase change heat storage system is one of the important ways to improve energy utilization efficiency, and it is also the only way for China to achieve sustainable development and high-quality development. High-efficiency phase change energy storage has become a research hotspot in current energy utilization in China.
[0003] The buried pipe heat accumulator is a key heat transfer device for realizing the heat exchange between the heat-carrying fluid and heat storage media such as soil. However, due to the limitations of the backfill material and the material of the buried pipe itself, the heat transfer performance of the buried pipe heat accumulator is relatively low. Therefore, there are still problems such as long heat storage time and low heat storage efficiency for the buried pipe combined with solar energy for heat storage. Content of the Utility Model
[0004] In view of the above problems, the utility model provides a finned U-shaped buried pipe heat accumulator combined with solar heat storage. The heat energy in the high-temperature solar heat fluid is transferred to the phase change backfill material in the shaft through the U-shaped finned pipe. The U-shaped finned structure can increase the heat exchange area between the heat exchange fluid and the phase change backfill material, and increase the disturbance of the fluid in the heat exchange pipe, so as to achieve the purpose of improving the heat storage efficiency of the solar heat accumulator, realize the heat storage process of solar heat, and realize the heat release process through heat exchange with the phase change backfill material when heat utilization is required. The heat storage and heat release processes can be repeated to achieve efficient heat exchange between the cold and hot fluids and the solid-liquid phase change backfill material.
[0005] To achieve the above object, the utility model provides a finned U-shaped buried pipe heat accumulator combined with solar heat storage, including: a shaft, a U-shaped finned pipe and a phase change backfill material;
[0006] The shaft is excavated on the ground, the phase change backfill material is filled in the shaft, and the U-shaped finned pipe is completely buried in the phase change backfill material;
[0007] Both upper ends of the U-shaped finned pipe include a heat exchange fluid inlet and a heat exchange fluid outlet. The heat exchange fluid for solar energy heat storage enters through the heat exchange fluid inlet and flows out through the heat exchange fluid outlet, enabling heat to be transferred through the U-shaped finned pipe to the phase change backfill material to achieve heat storage.
[0008] In the above technical solution, preferably, the U-shaped finned pipe adopts a 6-fin structure, the finned flow channel is connected to the circular pipe flow channel, and the finned flow channels are evenly and symmetrically distributed outside the circular pipe flow channel.
[0009] In the above technical solution, preferably, the U-shaped finned pipe is a PE pipe prepared by a high-temperature plasticizing sleeve film method.
[0010] In the above technical solution, preferably, the pipe spacing of the U-shaped finned pipe is 100 mm, and the fin length of the finned flow channel of the U-shaped finned pipe is 10 mm.
[0011] In the above technical solution, preferably, the phase change backfill material adopts a non-corrosive solid-liquid phase change material.
[0012] In the above technical solution, preferably, the burial depth of the U-shaped finned pipe in the shaft is at least 100 meters.
[0013] Compared with the prior art, the beneficial effects of the present utility model are as follows: The heat energy in the solar high-temperature heat fluid is transferred to the phase change backfill material in the shaft through the U-shaped finned pipe. The U-shaped fin structure increases the heat exchange area between the heat exchange fluid and the phase change backfill material, increases the disturbance of the fluid in the heat exchange tube, improves the heat storage efficiency of the solar heat accumulator, can realize the heat storage process of solar heat, and can realize the heat release process through heat exchange with the phase change backfill material when heat utilization is required. The heat storage and heat release processes can be repeated, realizing efficient heat exchange between cold and hot fluids and the solid-liquid phase change backfill material. BRIEF DESCRIPTION OF THE DRAWINGS
[0014] Figure 1 It is a three-dimensional structural schematic diagram of a finned U-shaped underground pipe heat accumulator with solar heat storage disclosed in an embodiment of the present utility model;
[0015] Figure 2 It is a top view structural schematic diagram of a finned U-shaped underground pipe heat accumulator with solar heat storage disclosed in an embodiment of the present utility model;
[0016] Figure 3 It is a comparison schematic diagram of the heat storage capacity of the 6-fin U-shaped finned pipe disclosed in an embodiment of the present utility model compared with other forms of pipes;
[0017] Figure 4Schematic diagram of the liquid state of the phase change backfill material around the U-shaped finned pipe in an embodiment of the present utility model.
[0018] In the figure, the corresponding relationship between each component and the reference numeral is as follows:
[0019] 1. Heat exchange fluid inlet, 2. Heat exchange fluid outlet, 3. U-shaped finned pipe, 4. Shaft, 5. Phase change backfill material, 6. Soil. Detailed implementation manners
[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present utility model clearer, the technical solutions in the embodiments of the present utility model will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present utility model. Obviously, the described embodiments are some, but not all, of the embodiments of the present utility model. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present utility model without creative efforts shall fall within the protection scope of the present utility model.
[0021] The following further describes the present utility model in detail with reference to the accompanying drawings:
[0022] As Figure 1 and Figure 2 shown, a finned U-shaped ground heat storage device with solar heat storage provided according to the present utility model includes: a shaft 4, a U-shaped finned pipe 3, and a phase change backfill material 5;
[0023] A shaft 4 is excavated on the ground, the phase change backfill material 5 is filled in the shaft 4, and the U-shaped finned pipe 3 is completely buried in the phase change backfill material 5;
[0024] The upper ends on both sides of the U-shaped finned pipe 3 include a heat exchange fluid inlet 1 and a heat exchange fluid outlet 2. The heat exchange fluid for solar heat storage enters through the heat exchange fluid inlet 1 and flows out through the heat exchange fluid outlet 2, so that heat is transferred to the phase change backfill material 5 through the U-shaped finned pipe 3 to achieve heat storage.
[0025] In this embodiment, the heat energy in the high-temperature solar heat exchange fluid is transferred to the phase change backfill material 5 in the shaft 4 through the U-shaped finned pipe 3. The U-shaped fin structure increases the heat exchange area between the heat exchange fluid and the phase change backfill material 5, increases the disturbance of the fluid in the heat exchange pipe, improves the heat storage efficiency of the solar heat storage device, can realize the heat storage process of solar heat, and can realize the heat release process through heat exchange with the phase change backfill material 5 when heat utilization is required. The heat storage and heat release processes can be repeated, realizing efficient heat exchange between the cold and hot fluids and the solid-liquid phase change backfill material 5.
[0026] Specifically, during implementation, the geological conditions suitable for the finned U-shaped buried pipe heat accumulator are rock and saturated water soil geological types. A vertical shaft 4 is excavated under the corresponding geological conditions. The vertical shaft 4 is filled with a phase change backfill material 5. The outside of the phase change backfill material 5 (i.e., around the vertical shaft 4) is soil 6. The U-shaped finned pipe 3 is buried in the phase change backfill material 5. During the heat storage process, solar heat energy is stored in the phase change backfill material 5 through a medium such as water. When the stored heat reaches the maximum heat storage capacity of the phase change backfill material 5, the heat will continue to be transferred into the soil 6 and rock for storage. When heating is required, the heat in the phase change backfill material 5, soil 6, and rock in the vertical shaft 4 is exchanged through a medium such as water.
[0027] In the above embodiment, preferably, the U-shaped finned pipe 3 adopts a 6-fin structure. The finned flow channel is connected to the circular pipe flow channel, and the finned flow channels are evenly and symmetrically distributed outside the circular pipe flow channel. This heat exchange pipe with a special finned pipe wall enhances the disturbance of the heat exchange fluid flowing through the U-shaped finned pipe 3, destroys the flow boundary layer, and thus strengthens heat transfer. Moreover, the heat exchange area between the finned pipe and the phase change backfill material 5 is increased, thereby improving the heat exchange efficiency between the phase change backfill material 5 and the heat exchange fluid.
[0028] As Figure 3 shown, specifically, for the U-shaped finned pipe 3 with a 6-fin structure, compared with the U-shaped pipes with a 4-fin structure and a non-finned structure, under the same conditions, from the comparison of the heat storage capacity of the phase change backfill material 5 around it, it can be seen that the U-shaped finned pipe 3 with a 6-fin structure can significantly improve the heat exchange efficiency between the phase change backfill material 5 and the heat exchange fluid.
[0029] In the above embodiment, preferably, the U-shaped finned pipe 3 is a PE pipe prepared by a high-temperature plasticizing sleeve film method, which improves the heat exchange efficiency between the heat exchange fluid and the phase change backfill material 5 and effectively alleviates the problem of slow heat exchange rate caused by the self-nature of the PE pipe and the phase change backfill material 5.
[0030] In the above embodiment, preferably, the inner and outer diameters of the U-shaped finned pipe 3 are 26 mm and 29 mm respectively, the pipe spacing is 100 mm, and the fin length of the finned flow channel of the U-shaped finned pipe 3 is 10 mm.
[0031] In the above embodiment, preferably, the phase change backfill material 5 adopts a non-corrosive solid-liquid phase change material.
[0032] In the above embodiment, preferably, the burial depth of the U-shaped finned pipe 3 in the vertical shaft 4 is at least 100 meters. In the vertical shaft 4 at this depth, the heat storage and heat release processes of the phase change backfill material 5 are less affected by the surface environment, and the heat storage efficiency and stability are higher.
[0033] In order to effectively store the heat of solar energy storage according to the above embodiments, the heat exchange fluid inlet 1 of the U-shaped finned pipe 3 is connected to the outlet of the solar energy storage. The high-temperature fluid medium (i.e., the heat exchange fluid) from the solar collector passes through the entire U-shaped finned pipe 3 through the heat exchange fluid inlet 1 and flows out from the heat exchange fluid outlet 2. In the U-shaped finned pipe 3, the heat exchange fluid exchanges heat with the phase change backfill material 5 outside the U-shaped finned pipe 3 through the pipe wall. As Figure 4 shown, during the heat storage process, the phase change backfill material 5 will gradually start to melt from near the pipe wall, changing from a solid state to a liquid state. The heat energy is continuously converted into latent heat and stored in the phase change backfill material 5 until the solid phase change heat storage material is completely converted into a liquid state. After that, the heat storage capacity of the phase change backfill material 5 reaches saturation, and the heat will continue to be transferred into the soil 6 and rocks for storage.
[0034] It can also be seen from this liquid phase diagram that the heat exchange efficiency of the U-shaped finned pipe 3 with a 6-fin structure is higher than that of the circular non-finned pipe. Under the same conditions, the liquid phase ratio of the phase change backfill material 5 around the U-shaped finned pipe 3 is higher, that is, more phase change backfill material 5 changes from a solid state to a liquid state, storing more heat.
[0035] When it is necessary to utilize the heat in the heat storage device (such as for heating), the heat in the phase change backfill material 5, soil 6 and rocks in the shaft 4 is exchanged through a medium such as water. The cold fluid enters along the heat exchange fluid inlet 1, and after heat exchange through the long finned U-shaped pipe, it flows out from the heat exchange fluid outlet 2. At this time, the cold fluid absorbs the heat stored in the phase change backfill material 5 and soil 6 through the pipe wall. When the phase change backfill material 5 releases part of the heat, the liquid phase change backfill material 5 near the pipe wall of the U-shaped finned pipe 3 gradually solidifies. As the heat release increases, the phase change backfill material 5 changes from a liquid state to a solid state, and the temperature of the heat exchange fluid rises. The high-temperature fluid flowing out through the heat exchange fluid outlet 2 supplies the heat it carries to the user for use.
[0036] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A finned U-shaped underground heat accumulator with solar heat storage, characterized in that: include: shafts, U-fin pipes, and phase-change backfill materials; The vertical shaft is formed by excavating on the ground, the phase-change backfill material is filled in the vertical shaft, and the U-shaped fin-type pipeline is completely buried in the phase-change backfill material; The upper ends of both sides of the U-shaped finned pipe include a heat exchange fluid inlet and a heat exchange fluid outlet. The heat exchange fluid for solar heat storage enters through the heat exchange fluid inlet and flows out through the heat exchange fluid outlet, so that the heat is transferred to the phase change backfill material through the U-shaped finned pipe to realize heat storage.
2. The finned U-shaped underground heat accumulator with solar thermal storage according to claim 1 is characterized in that: The U-shaped finned pipe adopts a 6-finned structure, the finned flow channel is connected with the circular tube flow channel, and the finned flow channel is evenly and symmetrically distributed on the outside of the circular tube flow channel.
3. The finned U-shaped underground heat accumulator with solar thermal storage according to claim 1 is characterized in that: The U-shaped finned pipe is a PE pipe prepared by a high-temperature plasticized film coating method.
4. The finned U-shaped underground heat accumulator with solar thermal storage according to claim 1 is characterized in that: The distance between the tubes of the U-shaped fin-type pipeline is 100 mm, and the wing length of the fin-type flow channel of the U-shaped fin-type pipeline is 10 mm.
5. The finned U-shaped underground heat accumulator with solar thermal storage according to claim 1 is characterized in that: The phase change backfill material is a non-corrosive solid-liquid phase change material.
6. The finned U-shaped underground heat accumulator with solar thermal storage according to claim 1 is characterized in that: The U-shaped finned pipeline is buried at a depth of at least 100 meters in the vertical shaft.