Phase-change energy tubular pile for sectional backfilling of composite phase-change material
By backfilling different phase change temperature material groups in the phase change energy pile in different zones, the problem of low liquefaction rate caused by single phase change material is solved, achieving more efficient cross-seasonal energy storage and heat exchange performance, and maintaining the stability of PHC pipe piles.
Patent Information
- Application Number
- CN202520327534.9
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-27
- Publication Date
- 2026-02-10
- Estimated Expiration
- 2035-02-27
AI Technical Summary
The existing phase change energy piles use a single phase change material and fail to fully consider the temperature differences between underground soil layers and the axial temperature difference of the heat exchange tubes, resulting in a low PCM liquefaction rate and affecting the cross-seasonal energy storage effect.
A method of zonal backfilling with composite phase change materials is adopted. Based on different soil depths and radial heat transfer characteristics of heat exchange tubes, phase change material groups with different phase change temperatures are encapsulated in layers and zones to form shallow, medium and deep layer structures, thereby optimizing the liquefaction rate and heat exchange direction of PCM.
It improves the liquefaction rate and latent heat utilization rate of PCM, optimizes heat exchange performance, enhances cross-seasonal energy storage effect, and maintains the mechanical properties of PHC pipe piles while reducing operating costs.
Smart Images
Figure CN223893355U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of ground source heat pump and underground energy structure technology, specifically a phase change energy pipe pile with composite phase change material for zoned backfilling. Background Technology
[0002] PHC pipe piles not only possess high mechanical strength, enabling them to serve as building foundations to bear building loads, but also feature a hollow interior. This allows for the installation of heat exchangers within the internal space, extracting heat from the underground soil to provide cooling and heating for the building. Additionally, the remaining hollow portion is filled with different types of phase change materials and backfill soil for heat exchange in winter and summer, utilizing the latent heat of phase change materials to enhance the cross-seasonal energy storage effect of the buried pipes.
[0003] However, the materials currently used for phase change backfilling in phase change energy piles are relatively limited and cannot adequately account for the temperature differences between different soil layers due to soil stratification, the temperature difference of the fluid along the axial direction of the heat exchange pipe, and the fact that heat exchange in phase change piles is primarily radial, resulting in a certain degree of heat exchange temperature difference in the radial direction of the heat exchange pipe. The combined effect of these factors means that the single phase change material cannot completely undergo phase change during operation, thus failing to maximize the utilization of the latent heat of phase change for cross-seasonal energy storage in buried pipes, leading to unsatisfactory heat exchange performance.
[0004] Therefore, it is necessary to design a phase change energy pipe pile with composite phase change material partition backfill, which can effectively utilize the effective heat exchange space inside the pipe pile while taking into account the mechanical bearing stability of the pile foundation, and solve the problem of low PCM liquefaction rate. Utility Model Content
[0005] The purpose of this invention is to overcome the above-mentioned shortcomings and defects, and to provide a phase change energy pipe pile with composite phase change material backfilling in a partitioned manner, so as to solve the problem of single phase change material backfilling, improve the liquefaction rate of PCM, and optimize the effect of buried pipe cross-seasonal energy storage.
[0006] To achieve the above objectives, this utility model provides the following technical solution: a phase change energy pipe pile with composite phase change material partitioned backfill, comprising a concrete pipe pile body, wherein a sleeve heat exchange pipe is coaxially arranged inside the pile body; and backfill soil circumferentially surrounding the concrete pipe pile body;
[0007] A vertically layered composite phase change structure, including:
[0008] The shallow encapsulation body is located in the upper region of the pile body and contains a first shallow phase change material group, a second shallow phase change material group, and a third shallow phase change material group distributed radially.
[0009] The middle layer encapsulation body is located in the middle region of the pile body and is internally encapsulated with a first middle layer phase change material group, a second middle layer phase change material group and a third middle layer phase change material group distributed radially.
[0010] The deep encapsulation body is located in the lower region of the pile body and contains a first deep phase change material group, a second deep phase change material group, and a third deep phase change material group distributed radially.
[0011] Backfill soil is used to fill the space between each encapsulation body and the pile.
[0012] Preferably, the shell-and-tube heat exchanger consists of an outer tube and an inner tube arranged coaxially, forming an annular flow channel between the outer tube and the inner tube; the bottom of the outer tube is connected to the inner tube, forming a counter-current channel between the outer tube and the inner tube, with the outer tube flowing downwards and the inner tube flowing upwards; the top of the outer tube is provided with an inlet connected to the heat pump system, and the top of the inner tube is provided with an outlet connected to the heat pump system.
[0013] Preferably, each phase change material group includes two categories: summer phase change materials and winter phase change materials;
[0014] The summer phase transition temperatures of the shallow, middle, and deep phase change material groups decrease sequentially from the inside to the outside along the radial direction.
[0015] The winter phase change temperature of the shallow, middle, and deep phase change material groups increases radially from the inside to the outside.
[0016] Preferably, the summer phase transition temperature of the shallow, middle, and deep phase change material groups decreases sequentially from top to bottom along the depth direction; the winter phase transition temperature of the shallow, middle, and deep phase change material groups increases sequentially from top to bottom along the depth direction.
[0017] Preferably, each package has a three-layer concentric ring structure, including:
[0018] The first to third annular cavities of the shallow encapsulation body correspond to the encapsulation of the first to third shallow phase change material groups, respectively.
[0019] The first to third annular cavities of the middle layer encapsulation body respectively correspond to the encapsulation of the first to third middle layer phase change material groups;
[0020] The first to third annular cavities of the deep encapsulation body correspond to the first to third deep phase change material groups, respectively.
[0021] Preferably, the concrete pipe pile body is a steel fiber reinforced concrete structure; each encapsulation body is a ring-shaped column made of PE material, with a hot-melt sealing structure on its upper and lower end faces; each ring-shaped column has three concentric ring-shaped cavities inside, and the number of radial ring cavities and the number of longitudinal encapsulation bodies can be expanded according to the actual situation.
[0022] Compared with the prior art, the beneficial effects of this utility model are as follows:
[0023] 1. This utility model utilizes the available space inside the PHC pipe pile to backfill phase change material in sections. It can rationally select phase change materials with different phase change temperatures for backfilling based on the temperature distribution of different soil depths and the radial heat transfer characteristics of the fluid in the heat exchange pipe, thereby avoiding the problem that a single phase change material cannot completely undergo phase change.
[0024] 2. This invention improves the liquefaction rate of PCM. The heat exchange direction of phase change piles is primarily radial, resulting in a certain degree of temperature difference in the radial direction of the heat exchange tubes. By backfilling the phase change material in sections according to the radial heat transfer characteristics in winter and summer, the liquefaction rate of PCM can be effectively improved, fully utilizing the latent heat of phase change of the material. Furthermore, along the axial direction of the heat exchange tubes, due to the continuous heat exchange of the fluid inside the tubes, a temperature difference exists in the longitudinal direction. By backfilling the phase change material in sections in the longitudinal direction, the utilization rate of the latent heat of liquefaction of PCM can be further improved, optimizing the heat exchange performance of buried pipe cross-seasonal energy storage.
[0025] 3. This utility model can effectively utilize the heat and cold of the underground soil by rationally dividing and layering backfilling phase change materials with different phase change temperatures, thereby improving the heat exchange efficiency of energy pipe piles and thus improving the overall effect of cross-seasonal energy storage.
[0026] 4. This utility model improves heat exchange performance while maintaining the high strength mechanical properties of PHC pipe piles, ensuring their load-bearing stability as building pile foundations. Furthermore, each encapsulation layer is a ring-shaped column structure, internally composed of three ring-shaped cavities. The number of ring-shaped encapsulation layers and the number of internal radial cavities can be adjusted according to actual conditions, offering high flexibility and scalability to adapt to different engineering needs. By improving the latent heat utilization rate of PCM liquefaction, energy consumption can be reduced, operating costs lowered, resulting in significant environmental and economic benefits. It is suitable for a wide range of applications in ground source heat pumps and underground energy structures. Attached Figure Description
[0027] The accompanying drawings are provided to further understand the present invention and form part of the specification. They are used together with the embodiments of the present invention to explain the present invention and do not constitute a limitation thereof.
[0028] In the attached diagram:
[0029] Figure 1 This is a schematic diagram of an energy pipe pile structure with partitioned backfilling using composite phase change material provided in this embodiment;
[0030] Figure 2 This is a schematic diagram of the structure of the phase change material encapsulation body provided in this embodiment;
[0031] Figure labels: 1. Concrete pipe pile body; 2-1. Outer pipe; 2-2. Inner pipe; 3. Backfill soil; 4-1. First shallow phase change material group; 4-2. Second shallow phase change material group; 4-3. Third shallow phase change material group; 5-1. First intermediate phase change material group; 5-2. Second intermediate phase change material group; 5-3. Third intermediate phase change material group; 6-1. First deep phase change material group; 6-2. Second... 6-3. Middle layer phase change material group; 7-1. First shallow annular cavity; 7-2. Second shallow annular cavity; 7-3. Third shallow annular cavity; 8-1. First middle layer annular cavity; 8-2. Second middle layer annular cavity; 8-3. Third middle layer annular cavity; 9-1. First deep annular cavity; 9-2. Second deep annular cavity; 9-3. Third deep annular cavity. Detailed Implementation
[0032] The preferred embodiments of the present invention will be described below with reference to the accompanying drawings. It should be understood that the preferred embodiments described herein are for illustration and explanation only and are not intended to limit the present invention.
[0033] Example: Figure 1 and Figure 2 As shown, a phase change energy pipe pile with composite phase change material partitioned backfilling includes:
[0034] Concrete pipe pile body 1, casing heat exchange pipe, backfill soil 3, shallow phase change material group, middle phase change material group, deep phase change material group, shallow encapsulation body, middle encapsulation body, deep encapsulation body;
[0035] The concrete pipe pile body 1 is equipped with a casing heat exchange tube inside, and the casing heat exchange tube is wrapped with backfill soil 3. The shallow phase change material group, the middle phase change material group and the deep phase change material group are respectively encapsulated by the shallow encapsulation body, the middle encapsulation body and the deep encapsulation body. The shallow encapsulation body, the middle encapsulation body and the deep encapsulation body are located in the upper, middle and lower layers of the concrete pipe pile body 1 in the longitudinal direction, and are distributed between the backfill soil 3 and the concrete pipe pile body 1 in the radial direction.
[0036] The shell-and-tube heat exchanger includes an outer tube 2-1 and an inner tube 2-2, with the fluid flowing in an outward-inward-outward pattern. The tube type can be any design that facilitates construction and improves heat exchange performance. The inlet of the shell-and-tube heat exchanger is connected to the outlet of the condenser or evaporator in the heat pump system, and the outlet of the shell-and-tube heat exchanger is connected to the inlet of the condenser or evaporator in the heat pump system.
[0037] The shallow phase change material group includes: a first shallow phase change material group 4-1, a second shallow phase change material group 4-2, and a third shallow phase change material group 4-3; the intermediate phase change material group includes: a first intermediate phase change material group 5-1, a second intermediate phase change material group 5-2, and a third intermediate phase change material group 5-3; the deep phase change material group includes: a first deep phase change material group 6-1, a second deep phase change material group 6-2, and a third deep phase change material group 6-3; each of the shallow, intermediate, and deep phase change material groups includes different types of summer and winter phase change materials; the phase change temperature of each type of summer phase change material in the shallow, intermediate, and deep phase change material groups decreases sequentially in the radial direction; the phase change temperature of each type of winter phase change material in the shallow, intermediate, and deep phase change material groups increases sequentially in the radial direction.
[0038] The phase transition temperatures of the summer phase transition materials in the shallow phase transition material group, the middle phase transition material group, and the deep phase transition material group decrease sequentially along the depth direction; the phase transition temperatures of the winter phase transition materials in the shallow phase transition material group, the middle phase transition material group, and the deep phase transition material group increase sequentially along the depth direction.
[0039] The shallow encapsulation includes: a first shallow annular cavity 7-1, a second shallow annular cavity 7-2, and a third shallow annular cavity 7-3; the first shallow phase change material group 4-1 is encapsulated within the first shallow annular cavity 7-1, the second shallow phase change material group 4-2 is encapsulated within the second shallow annular cavity 7-2, and the third shallow phase change material group 4-3 is encapsulated within the third shallow annular cavity 7-3; the middle encapsulation includes: a first middle annular cavity 8-1, a second middle annular cavity 8-2, and a third middle annular cavity 8-3; the first middle phase change material group 5-1 is encapsulated within the first middle annular cavity 7-1. Within the annular cavity 8-1, the second intermediate phase change material group 5-2 is encapsulated within the second intermediate annular cavity 8-2, and the third intermediate phase change material group 5-3 is encapsulated within the third intermediate annular cavity 8-3; the deep encapsulation body includes: a first deep annular cavity 9-1, a second deep annular cavity 9-2, and a third deep annular cavity 9-3; the first deep phase change material group 6-1 is encapsulated within the second deep annular cavity 9-1, the second deep phase change material group 6-2 is encapsulated within the second deep annular cavity 9-2, and the third deep phase change material group 6-3 is encapsulated within the third deep annular cavity 9-3.
[0040] The concrete pipe pile body 1 is made of steel fiber reinforced concrete; the shallow encapsulation body, the middle encapsulation body, and the deep encapsulation body are all made of PE material; after each phase change material group is respectively loaded into the respective encapsulation body, the upper and lower surfaces of the encapsulation body are sealed with PE material by heat fusion sealing method and then placed inside the concrete pile body 1 in sequence; each encapsulation body is a ring-shaped column structure, which is composed of three ring-shaped cavities inside. The number of ring-shaped encapsulation bodies and the number of internal radial ring cavities can be increased or decreased according to the actual situation.
[0041] The working principle can be summarized as follows:
[0042] The shell-and-tube heat exchanger, as the core heat transfer component, is embedded in the concrete pipe pile and connected to the ground source heat pump system. The outer tube 2-1 is the inlet and the inner tube 2-2 is the outlet. In summer, the waste heat of the building is discharged into the ground through the condenser, and in winter, heat is absorbed from the ground through the evaporator, realizing heat energy storage and extraction.
[0043] The working process of this phase change energy pipeline pile can be summarized into the following steps, with summer and winter operation modes as the core:
[0044] 1. Summer Operation Process (Heat Dissipation and Energy Storage)
[0045] 1) Heat pump start-up
[0046] When the heat pump system switches to cooling mode, the high-temperature fluid (carrying the building's waste heat) at the condenser outlet is injected from the outer tube 2-1 of the shell-and-tube heat exchanger, flows through the pile body, and returns to the evaporator through the inner tube 2-2, forming a closed loop.
[0047] 2) Shallow layers preferentially absorb heat
[0048] The fluid heat is transferred to the surrounding backfill soil 3 and phase change material through the heat exchange tube wall. The shallow phase change material group (high phase change temperature) absorbs heat and melts first, storing sensible heat and latent heat. The heat is transferred radially from the inside to the outside, and the middle layer → deep layer materials respond in sequence (temperature gradient design avoids heat saturation), forming a stepped heat storage.
[0049] 3) Radial thermal diffusion enhancement
[0050] After the outer layer of summer material (low temperature) absorbs the basic heat, the inner layer of high-temperature phase change material (close to the heat exchange tube) further stores energy, forming an energy storage chain of "gradual heating from the outside to the inside" to maximize heat capacity utilization. The heat that is not completely consumed is sealed underground by the deep low phase change temperature material, which delays heat loss and realizes cross-seasonal energy storage.
[0051] 2. Winter Operation Procedure (Heat Extraction and Energy Supply)
[0052] 1) Heat pump switching to heating mode
[0053] When the heat pump starts in heating mode, the low-temperature fluid at the evaporator outlet is injected from the outer pipe 2-1, flows through the pile body to absorb heat, and then returns to the condenser through the inner pipe 2-2 to heat the building.
[0054] 2) Shallow layer preferential heat release
[0055] In the shallow winter phase change material group (low phase change temperature), the inflow of low-temperature fluid triggers solidification and heat release, and the low-temperature fluid inside the tube initially absorbs heat; the heat is absorbed by the outer tube fluid radially from the outside to the inside; the middle layer → deep layer phase change materials sequentially replenish the heat release.
[0056] 3) Shallow auxiliary insulation
[0057] Shallow low phase change temperature materials retain some latent heat of phase change in the near-surface low-temperature environment, reducing the impact of cold infiltration on deep heat storage; the natural heat of deep soil and the heat release of phase change materials are superimposed and continuously output through heat exchange tubes, ensuring the efficient operation of the heat pump.
[0058] Finally, it should be noted that the above description is merely a preferred embodiment of this utility model and is not intended to limit the utility model. Although the utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this utility model should be included within the protection scope of this utility model.
Claims
1. A phase change energy pipe pile with composite phase change material partitioned backfilling, characterized in that: Includes a concrete pipe pile body (1), which has a sleeve heat exchange pipe coaxially installed inside; and backfill soil (3) that circumferentially surrounds the concrete pipe pile body (1); A vertically layered composite phase change structure, including: The shallow encapsulation body is located in the upper region of the pile body and is encapsulated inside by a first shallow phase change material group (4-1), a second shallow phase change material group (4-2), and a third shallow phase change material group (4-3) distributed radially. The middle layer encapsulation body is located in the middle region of the pile body and is encapsulated inside by a first middle layer phase change material group (5-1), a second middle layer phase change material group (5-2), and a third middle layer phase change material group (5-3) distributed radially. The deep encapsulation body is located in the lower region of the pile body and contains a first deep phase change material group (6-1), a second deep phase change material group (6-2), and a third deep phase change material group (6-3) distributed radially. Backfill soil (3) is filled between each encapsulation body and the pile body (1).
2. The phase change energy pipe pile with composite phase change material partitioned backfilling according to claim 1, characterized in that: The shell-and-tube heat exchanger consists of an outer tube (2-1) and an inner tube (2-2) arranged coaxially. The bottom of the outer tube (2-1) is connected to the inner tube (2-2), and a counter-current channel is formed between the outer tube and the inner tube, with the outer tube flowing downward and the inner tube flowing upward. The top of the outer tube (2-1) is provided with an inlet connected to the heat pump system, and the top of the inner tube (2-2) is provided with an outlet connected to the heat pump system.
3. The phase change energy pipe pile with composite phase change material partitioned backfilling according to claim 1, characterized in that: Each phase change material group includes two categories: summer phase change materials and winter phase change materials; The summer phase transition temperatures of the shallow, middle, and deep phase change material groups decrease sequentially from the inside to the outside along the radial direction. The winter phase change temperature of the shallow, middle, and deep phase change material groups increases radially from the inside to the outside.
4. The phase change energy pipe pile with composite phase change material partitioned backfilling according to claim 1, characterized in that: The summer phase transition temperatures of the shallow, middle, and deep phase change material groups decrease sequentially from top to bottom along the depth direction; the winter phase transition temperatures of the shallow, middle, and deep phase change material groups increase sequentially from top to bottom along the depth direction.
5. A phase change energy pipe pile with partitioned backfilling of composite phase change material according to claim 1, characterized in that: Each package consists of a three-layer concentric ring structure, including: The first to third annular cavities (7-1, 7-2, 7-3) of the shallow encapsulation body correspond to the encapsulation of the first to third shallow phase change material groups (4-1, 4-2, 4-3), respectively. The first to third annular cavities (8-1, 8-2, 8-3) of the middle layer encapsulation body correspond to the encapsulation of the first to third middle layer phase change material groups (5-1, 5-2, 5-3), respectively. The first to third annular cavities (9-1, 9-2, 9-3) of the deep encapsulation body correspond to the encapsulation of the first to third deep phase change material groups (6-1, 6-2, 6-3), respectively.
6. The phase change energy pipe pile with composite phase change material partitioned backfilling according to claim 1, characterized in that: The concrete pipe pile body (1) is a steel fiber concrete structure; each encapsulation body is a ring-shaped column made of PE material, and its upper and lower end faces are provided with a hot melt sealing structure; each ring-shaped column has three concentric ring-shaped cavities inside, and the number of radial ring cavities and the number of longitudinal encapsulation bodies are expanded according to the actual situation.