Low-stress phase change energy pile, ground source heat pump heat exchange system and construction method of ground source heat pump heat exchange system

Abstract

The low-stress phase-change energy pile comprises at least one pile single body, each pile single body comprises a pile body, a cylindrical fixing support, an energy pipe and concrete, the cylindrical fixing support, the energy pipe and the concrete are located in the pile body, the energy pipe is fixed in the fixing support, and the energy pipe and the fixing support are preset in the pile body. The pile body is filled with the concrete, the inlet end and the outlet end of the energy pipe extend out of the concrete, a pipe body of the energy pipe comprises a sleeve-shaped inner pipe and an outer pipe, the cross sections of the inner pipe and the outer pipe are shaped like a Chinese character'hui ', and the inner pipe of the sleeve-shaped energy pipe is used for introducing cold and hot solutions for heat exchange; and the space between the inner pipe and the outer pipe of the sleeve type energy pipe is filled with a phase change material. The invention further provides a ground source heat pump heat exchange system comprising the low-stress phase change energy pile, a construction method of the ground source heat pump heat exchange system and a heat exchange method of the ground source heat pump heat exchange system.

Description

Technical Field

[0001] The present invention belongs to the technical field of civil engineering, and in particular relates to a low-stress phase-change energy pile, a ground-source heat pump heat exchange system including the low-stress phase-change energy pile, and a construction method thereof. Background Art

[0002] In order to alleviate the problems of high energy consumption, severe environmental pollution and low energy utilization rate in the operation of buildings, scholars and engineers at home and abroad have been trying new processes and methods for the utilization of shallow geothermal energy based on the experience of ground source heat pump technology. Subsequently, a new type of building energy-saving technology, energy pile technology (energy pile, energy pile), was developed.

[0003] Among them, the energy pile technology mainly combines the traditional buried pipe ground source heat pump system with the pile foundation of the building, that is, an underground heat exchange pipeline system is implanted in various forms of pile foundations of the building, so as to not only realize the rational utilization of space resources, but also obtain shallow geothermal energy resources from the strata, such as Figure 1 , Figure 2 The main principle of this type of energy pile is to achieve heat exchange between the pile and the soil through the temperature difference between the circulating solution medium in the heat exchange tube and the rock and soil around the pile, so as to use shallow geothermal energy to achieve the goal of cooling the above-ground buildings in summer and heating them in winter.

[0004] The optimization of energy piles is mainly focused on improving their heat transfer performance and heat exchange efficiency, which is usually achieved by optimizing the form of heat exchange tubes, changing the fluid in the tubes, etc. The above methods usually increase the number and length of buried pipes to expand the heat exchange area, which not only complicates the structure of the pile, but also easily causes large temperature stress in the pile body, thereby affecting the bearing capacity of the pile foundation and the safety of the upper building structure.

[0005] In addition, phase change materials are widely used in the field of building energy conservation. They can absorb or release a large amount of latent heat during the phase change process, thereby effectively regulating the ambient temperature. This type of phase change material is widely used in insulation materials for building walls or roofs, radiant heating systems, smart temperature-controlled windows, building energy storage units, etc. Some scholars subsequently applied the material to energy underground structures to increase the energy density of the structure and improve the heat exchange capacity, thereby reducing the underground space resources required for heat exchange. At present, the technical method for applying phase change materials in energy piles is mainly: adding phase change materials to concrete to change the physical properties of concrete, such as Figure 3As shown. Although the application of phase change concrete materials in energy piles has improved the thermal physical properties of the pile body to a certain extent, such as slowing down the temperature change rate of the pile body and the soil around the pile, and reducing the temperature change amplitude of the pile-soil structure. However, the current research on the mechanical properties of phase change concrete materials has not yet been clarified. Through current research, it is found that adding phase change materials to existing concrete piles will affect the mechanical properties of the pile body, thereby changing the bearing characteristics of the pile body. Moreover, the research on the application of such phase change materials in energy piles is still at the stage of similar model tests and numerical simulations, and it is difficult to apply them on a large scale on site. Summary of the invention

[0006] In view of the deficiencies in the prior art, an object of the present invention is to provide a low-stress phase change energy pile, a ground source heat pump heat exchange system including the low-stress phase change energy pile, and a construction method thereof.

[0007] To achieve the above purpose, the solution adopted by the present invention is as follows:

[0008] In the first aspect, the present invention provides a low-stress phase change energy pile, comprising at least one pile monomer, each pile monomer comprising a pile body and a cylindrical tube-type fixed bracket, an energy tube and concrete located in the pile body, wherein the energy tube is fixed in the fixed bracket, the energy tube and the fixed bracket are preset in the pile body, the concrete is filled in the pile body, the inlet end and the outlet end of the energy tube extend out of the concrete, the tube body of the energy tube comprises an inner tube and an outer tube in a sleeve-shaped manner with a U-shaped cross-section, the inner tube of the sleeve-type energy tube is used for passing cold and hot solutions for heat exchange, and the space between the inner tube and the outer tube of the sleeve-type energy tube is used for filling phase change material.

[0009] Preferably, the cylindrical tube-type fixed support is a steel cage, which includes a plurality of main bars and a plurality of stirrups. The main bars are vertically and evenly arranged along the circumference of the pile body, each stirrup is horizontally fixedly connected to the main bars, and the distance between two adjacent stirrups is equal. The sleeve-type energy tube is fixed on the main bars of the steel cage.

[0010] Preferably, the energy tube is in a U-shape, a W-shape or a spiral shape as a whole; preferably, the energy tube is in a W-shape as a whole.

[0011] Preferably, the phase change material is paraffin.

[0012] Preferably, the low stress phase change energy pile comprises a plurality of pile monomers connected in parallel.

[0013] In a second aspect, the present invention also provides a ground source heat pump heat exchange system, comprising a heat pump heat exchanger, an indoor air conditioning circulation system, a low stress phase change energy pile as described above buried in the soil, and soil around the pile body; the inlet end and the outlet end of the low stress phase change energy column are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger, and the second outlet end and the second inlet end of the heat pump heat exchanger are respectively connected to the inlet end and the outlet end of the indoor air conditioning circulation system.

[0014] Preferably, the indoor air conditioning circulation system includes a fan coil unit and / or a floor heating system, the fan coil unit is arranged in an indoor wall, and the floor heating system is arranged in an indoor floor base plate.

[0015] In a third aspect, the present invention further provides a construction method of the ground source heat pump heat exchange system as described above, comprising the following steps:

[0016] S1. According to the load of the building structure and the ground conditions, the cross-sectional diameter and pile length of the low-stress phase change energy pile, the size and number of main reinforcement and stirrups, and the pile spacing are designed. According to the temperature distribution of the shallow strata and the energy demand of the indoor air conditioning circulation system, the buried form of the energy pipe, the diameter and length of the inner and outer pipes are designed;

[0017] S2. Make several straight energy tubes, heat the phase change material to make it molten, and then pour it into the gap between the inner tube and the outer tube of the straight energy tube, and fill the sealing material into the gap between the two ends of the straight energy tube and the inner tube and the outer tube, and then connect the four straight energy tubes between the ends of the two sections of energy tubes with rubber tubes, and connect and reinforce the interface with metal clamps to make an overall W-shaped energy tube;

[0018] S3, tying the prepared energy tube to the steel cage, and then pouring concrete, the top of the energy tube extends a length from the upper side of the phase change energy pile body to form an inlet end and an outlet end connected to the heat pump heat exchanger, completing the production of a pile monomer, and then burying several such pile monomers in the soil, and the inlet end and the outlet end connected in parallel to each other are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger for input and output of cold and hot solutions in the heat exchange carrier;

[0019] S4. Connect the second outlet end and the second inlet end of the heat pump heat exchanger to the inlet end and the outlet end of the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system, respectively, to form a loop, so that the hot and cold energy after the pile-soil heat exchange enters the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system to adjust the indoor temperature.

[0020] In a fourth aspect, the present invention further provides a heat exchange method for the ground source heat pump heat exchange system as described above, comprising the following steps:

[0021] The hot and cold solutions from the heat pump heat exchanger flow into the inner tube of the energy pipe through the inlet end at the top of the low stress phase change energy pile. The hot and cold solutions flow in the inner tube of the energy pipe and perform heat exchange with the soil around the pile body.

[0022] Phase change material is filled between the inner tube and the outer tube of the energy tube. In summer, part of the heat of the hot solution circulating in the inner tube is stored in the phase change material between the inner tube and the outer tube. In winter, part of the coldness of the cold solution circulating in the inner tube is stored in the phase change material between the inner tube and the outer tube.

[0023] Finally, the circulating solution in the inner tube of the energy tube flows back to the heat pump heat exchanger from the top outlet, completing a thermal cycle.

[0024] Beneficial Effects

[0025] The present invention provides a low-stress phase-change energy pile and a ground-source heat pump heat exchange system including the low-stress phase-change energy pile. The low-stress phase-change energy pile adopts a sleeve-type energy pipe with a U-shaped cross-section. The inner pipe is used to pass hot and cold solutions for heat exchange, and the phase-change material is filled between the inner pipe and the outer pipe. On the basis of maintaining the internal structure of the existing energy pile body, the original heat transfer performance and heat exchange efficiency of the pile body can be maintained, and the influence of thermal stress caused by excessive temperature changes of the pile body on the pile body and the upper building structure can be effectively avoided. The mechanical properties of the pile body can be guaranteed to be stable and controllable to the greatest extent, so that it can be better applied to actual on-site projects. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 It is a structural schematic diagram of the winter and summer application conditions of the existing energy pile mentioned in the background technology of the present invention.

[0027] Figure 2 It is a schematic diagram of the cross-sectional structure of the existing energy pile mentioned in the background technology of the present invention and the heat exchange mechanism of winter and summer working conditions.

[0028] Figure 3 It is a schematic diagram of the cross-sectional structure of the existing phase change concrete material energy pile mentioned in the background technology of the present invention.

[0029] Figure 4 It is a front view of a pile monomer of the low stress phase change energy pile involved in the present invention.

[0030] Figure 5 for Figure 4 Top view of the .

[0031] Figure 6 It is a schematic structural diagram of the source heat pump heat exchange system involved in the present invention. DETAILED DESCRIPTION

[0032] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0033] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. 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.

[0034] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0035] In the description of the present invention, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inside", "outside", etc. indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, or the positions or positional relationships in which the product of the invention is usually placed when in use. They are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific position, be constructed and operated in a specific position, and therefore cannot be understood as limiting the present invention. In addition, the terms "first", "second", "third", etc. are only used to distinguish the description, and cannot be understood as indicating or implying relative importance.

[0036] In addition, the terms "horizontal", "vertical" and the like do not mean that the components are required to be absolutely horizontal or suspended, but can be slightly tilted. For example, "horizontal" only means that its direction is more horizontal than "vertical", and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0037] In the description of the present invention, it is also necessary to explain that, unless otherwise clearly specified and limited, the terms "set", "install", "connect", and "connect" 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 a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0038] To this end, the following solutions are proposed:

[0039] See also Figure 4 , Figure 5 The present invention provides a low stress phase change energy pile 100, comprising at least one pile monomer 110, each pile monomer 110 comprises a pile body 111 and a cylindrical tube-type fixed bracket 112, an energy pipe 113 and concrete 114 located in the pile body 111. The energy pipe 113 is fixed in the fixed bracket 112, the energy pipe 113 and the fixed bracket 112 are preset in the pile body 111, the concrete 114 is filled in the pile body 111, the inlet end and the outlet end of the energy pipe 113 extend out of the concrete 114, the pipe body of the energy pipe 113 comprises an inner pipe 113a and an outer pipe 113b in a sleeve-shaped cross section, the inner pipe 113a of the sleeve-shaped energy pipe 113 is used to pass the cold and hot solutions for heat exchange, and the inner pipe 113a and the outer pipe 113b of the sleeve-shaped energy pipe 113 are used to fill the phase change material.

[0040] In one embodiment of the present invention, the cylindrical fixed bracket 112 is a steel cage, including a plurality of main bars 112a and a plurality of stirrups 112b, wherein the main bars 112a are evenly arranged vertically along the circumference of the pile body 111, each stirrup is horizontally fixedly connected to the main bars 112a, and the distance between two adjacent stirrups should be equal, and the sleeve-type energy tube 113 is fixed on the main bars 112a of the steel cage 112. Specifically, the diameter, model size, etc. of the main bars 112a and stirrups 112b of the steel cage 112 in the pile body 111 are determined by the load size of the building and the pile foundation design. In the present invention, for example, six steel bars with a diameter of 10 mm are used as the main bars 112a of the steel cage 112, and steel bars with a diameter of 6 mm are used as the stirrups 112b of the steel cage 112. The spacing between two adjacent stirrups 112b can be 200 mm, and the main bars 112a and stirrups 112b are tied tightly with wire.

[0041] In one embodiment of the present invention, the energy tube 113 as a whole can be U-shaped, W-shaped or spiral-shaped. In the present invention, the arrangement of the energy tube 113 in the pile body 111 is preferably W-shaped, and the two side tubes of the W-shaped energy tube 113 can be tied to the two main bars 112a of the steel cage 112 by, for example, cable ties or steel wires.

[0042] In the low stress phase change energy pile 100 of the present invention, the outer diameter of the inner tube 113a of the sleeve type energy tube 113 can be 20-30mm, the outer diameter of the outer tube 113b can be 25-50mm, and the wall thickness of the inner tube 113a and the outer tube 113b can be 2-4mm, for example 3mm.

[0043] In the low stress phase change energy pile 100 of the present invention, the heat exchange circulation solution circulates in the inner tube 113a of the sleeve type energy tube 113, and its function is to form heat exchange with the interior of the building through the heat pump heat exchanger host, thereby realizing the functions of cooling in summer and heating in winter of the building. The commonly used heat exchange circulation solution is water or other heat carrier fluids.

[0044] In the low stress phase change energy pile 100 of the present invention, the inner tube 113a and the outer tube 113b of the sleeve type energy tube 113 are filled with phase change material. The phase change material (PCM) sleeve 113b can change the physical state with the change of temperature to absorb or release latent heat, and can store or release a large amount of energy at a nearly constant temperature during the melting or solidification process. Phase change materials (PCM) can be divided into inorganic phase change materials and organic phase change materials according to their chemical composition. Common inorganic PCMs, such as inorganic composite CaCl 2 6H 2 O material, common organic PCM, such as paraffin (PW), polyethylene glycol (PEG), fatty acid, etc., usually paraffin is used as the phase change material. In the present invention, the phase change material is filled between the inner tube 113a and the outer tube 113b of the sleeve type energy tube 113, for example, by pouring the melted phase change material paraffin.

[0045] In the low stress phase change energy pile 100 of the present invention, the pile body 111 can be cast on site or prefabricated. The energy pipe 113 and the fixing bracket 112 can be preset in the pile body 111 first, and then the concrete 114 is poured and filled in the gap between the pile body 111 and the energy pipe 113 and the fixing bracket 112. Figure 4 , Figure 5 shown.

[0046] The present invention also provides a ground source heat pump heat exchange system 200, such as Figure 6 As shown, it includes a heat pump heat exchanger 300, an indoor air conditioning circulation system (not shown in the figure), the low stress phase change energy pile 100 as described above buried in the soil, and the soil 400 around the pile body.

[0047] Specifically, in the geothermal heat pump heat exchange system 200 of the present invention, the low stress phase change energy pile 100 includes a plurality of pile monomers 110, which are arranged in parallel in the soil 400, and heat is exchanged with the surrounding soil 400 through each pile monomer 110. The distance between two adjacent pile monomers 110 is equal or unequal, and can be arranged according to actual design requirements. Preferably, the distance between two adjacent pile monomers 110 is equal, and the pile spacing is, for example, 1.0-7.0m.

[0048] Further, in the geothermal heat pump heat exchange system 200 of the present invention, the inlet end and the outlet end of the low stress phase change energy column 100 are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger 300, and the second outlet end and the second inlet end of the heat pump heat exchanger 300 are respectively connected to the inlet end and the outlet end of the indoor air conditioning circulation system. In some embodiments, the indoor air conditioning circulation system includes a fan coil unit and / or a floor heating system, wherein the fan coil unit is arranged in the indoor wall, and the floor heating system is arranged in the indoor floor bottom plate.

[0049] In the ground source heat pump heat exchange system 200 provided by the present invention, the heat exchange method includes:

[0050] The hot and cold solutions from the heat pump heat exchanger 300 flow into the inner tube 113a of the energy pipe 113 through the inlet end at the top of the low stress phase change energy pile 100. The hot and cold solutions flow in the inner tube 113a of the energy pipe 113 and perform heat exchange with the surrounding soil 400.

[0051] Phase change material is filled between the inner tube 113a and the outer tube 113b of the energy tube 113. In summer, part of the heat of the hot solution circulating in the inner tube 113a is stored in the phase change material between the inner tube 113a and the outer tube 113b. In winter, part of the coldness of the cold solution circulating in the inner tube 113a is stored in the phase change material between the inner tube 113a and the outer tube 113b.

[0052] Finally, the circulating solution in the inner tube 113a of the energy tube 113 flows back to the heat pump heat exchanger 300 from the top outlet, completing a heat cycle, and finally the exchanged heat or cold is transported to the fan coil and / or floor heating system of the indoor air conditioning circulation system through the heat pump heat exchanger 300, thereby achieving the purpose of regulating the indoor air temperature of the building.

[0053] In the ground source heat pump heat exchange system 200 provided by the present invention, by filling a circle of phase change material between the inner tube 113a and the outer tube 113b, during the heat exchange cycle, the cold and heat in the cold and hot solutions in the inner tube 113a can be more concentrated, avoiding energy dissipation and improving the heat transfer performance in the inner tube. On the other hand, it also delays the temperature change rate of the pile body 111 and the soil body 400 around the pile body 111 under long-term operation to a certain extent, reduces the temperature change amplitude of the pile soil, and avoids the influence of the thermal stress generated by the temperature accumulation of the pile soil structure on the pile body itself and the upper building structure. By filling the phase change material between the inner tube 113a and the outer tube 113b to form the outer ring of the sleeve type energy pipe 113, the pile body structure and material properties can be kept unchanged to the greatest extent, the bearing characteristics of the pile body are maintained, and the defect of adding phase change material to the existing concrete pile body in the prior art that the mechanical properties of the pile body will be affected is overcome.

[0054] The present invention not only maintains the heat transfer performance and heat exchange efficiency of the energy pile, but also alleviates the influence of thermal stress on the pile body caused by temperature accumulation without changing the internal structural form and material properties of the energy pile body. This can maximize the stability and controllability of the mechanical properties of the pile body and the safety of the upper building structure, so that it can be better applied to actual on-site projects.

[0055] The present invention further provides a construction method for the above-mentioned ground source heat pump heat exchange system, comprising the following steps:

[0056] S1. According to the load of the building structure and the ground conditions, the cross-sectional diameter and pile length of the pile monomer 110 of the low stress phase change energy pile 100, the size and number of the main reinforcement 112a and the stirrups, and the pile spacing are designed. According to the temperature distribution of the shallow ground and the energy demand of the indoor air conditioning circulation system, the buried form of the energy pipe 113, the diameter and length of the inner pipe 113a and the outer pipe 113b are designed;

[0057] S2. Make several straight energy tubes 113, heat the phase change material to make it molten, and then pour it into the gap between the inner tube 113a and the outer tube 113b of the straight energy tube 113, and fill the sealing material into the gap between the two ends of the straight energy tube 113 and the inner tube 113a and the outer tube 113b, and then connect the four straight energy tubes 113 between the two ends with a rubber tube, and connect and reinforce the interface with a metal clamp to make an overall W-shaped energy tube 113;

[0058] S3, tie the prepared energy tube 113 to the steel cage 112, and then pour concrete 114, the top of the energy tube 113 extends a length from the upper side of the pile body 111 of the phase change energy pile 100, forming an inlet end and an outlet end connected to the heat pump heat exchanger 300, completing the production of a pile monomer 110, and then burying several such pile monomers 110 in the soil, and the inlet end and the outlet end connected in parallel with each other are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger 300, for input and output of cold and hot solutions in the heat exchange carrier;

[0059] S4. Connect the second outlet end and the second inlet end of the heat pump heat exchanger 300 to the inlet end and the outlet end of the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system, respectively, to form a loop, so that the hot and cold energy after the pile-soil heat exchange enters the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system to adjust the indoor temperature.

[0060] The present invention provides a low-stress phase-change energy pile and a ground-source heat pump heat exchange system including the low-stress phase-change energy pile. The low-stress phase-change energy pile adopts a sleeve-type energy pipe with a U-shaped cross-section. The outer ring of the U-shaped sleeve is a phase-change material. On the basis of maintaining the internal structure of the existing energy pile body, the original heat transfer performance and heat exchange efficiency of the pile body can be maintained, and the influence of the thermal stress generated by excessive temperature changes of the pile body on the pile body and the upper building structure can be effectively avoided. The mechanical properties of the pile body can be guaranteed to be stable and controllable to the greatest extent, so that it can be better applied to actual on-site projects.

[0061] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.

Claims

1. A low stress phase change energy pile, characterized in that: It comprises at least one pile monomer, each pile monomer comprises a pile body and a cylindrical tube-type fixing bracket, an energy tube and concrete located in the pile body, wherein the energy tube is fixed in the fixing bracket, the energy tube and the fixing bracket are preset in the pile body, the concrete is filled in the pile body, the inlet end and the outlet end of the energy tube extend out of the concrete, the tube body of the energy tube comprises an inner tube and an outer tube which are sleeve-shaped and have a U-shaped cross-section, the inner tube of the sleeve-type energy tube is used for passing cold and hot solutions for heat exchange, and the space between the inner tube and the outer tube of the sleeve-type energy tube is used for filling phase change material.

2. The low stress phase change energy pile according to claim 1, characterized in that: The cylindrical tube-type fixed support is a steel cage, which includes multiple main bars and multiple stirrups. The main bars are evenly arranged vertically along the circumference of the pile body. Each stirrup is horizontally fixedly connected to the main bar, and the distance between two adjacent stirrups is equal. The sleeve-type energy pipe is fixed on the main bars of the steel cage.

3. The low stress phase change energy pile according to claim 1, characterized in that: The energy tube is in a U-shape, a W-shape or a spiral shape as a whole; preferably, the energy tube is in a W-shape as a whole.

4. The low stress phase change energy pile according to claim 1, characterized in that: The phase change material is paraffin.

5. The low stress phase change energy pile according to claim 1, characterized in that: The low stress phase change energy pile comprises a plurality of pile monomers connected in parallel.

6. A ground source heat pump heat exchange system, characterized in that: It comprises a heat pump heat exchanger, an indoor air conditioning circulation system, a low stress phase change energy pile as described in any one of claims 1 to 5 buried in the soil, and soil around the pile body; the inlet end and the outlet end of the low stress phase change energy column are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger, and the second outlet end and the second inlet end of the heat pump heat exchanger are respectively connected to the inlet end and the outlet end of the indoor air conditioning circulation system.

7. The ground source heat pump heat exchange system according to claim 6, characterized in that: The indoor air conditioning circulation system includes a fan coil unit and / or a floor heating system. The fan coil unit is arranged in an indoor wall, and the floor heating system is arranged in an indoor floor bottom plate.

8. A construction method for a ground source heat pump heat exchange system according to claim 6 or 7, characterized in that: The steps include: S1. According to the load of the building structure and the ground conditions, the cross-sectional diameter and pile length of the low-stress phase change energy pile, the size and number of main reinforcement and stirrups, and the pile spacing are designed. According to the temperature distribution of the shallow strata and the energy demand of the indoor air conditioning circulation system, the buried form of the energy pipe, the diameter and length of the inner and outer pipes are designed; S2. Make several straight energy tubes, heat the phase change material to make it molten, and then pour it into the gap between the inner tube and the outer tube of the straight energy tube, and fill the sealing material into the gap between the two ends of the straight energy tube and the inner tube and the outer tube, and then connect the four straight energy tubes between the two sections of energy tubes through rubber tubes, and reinforce the interface with metal clamps to make an overall W-shaped energy tube; S3. Tie the prepared energy tube to the steel cage, and then pour concrete. The top of the energy tube extends a certain length from the upper side of the phase change energy pile to form a connection with the heat pump heat exchanger. The inlet end and the outlet end are connected to complete the production of a pile monomer, and then several such pile monomers are buried in the soil. The inlet end and the outlet end connected in parallel are respectively connected to the first outlet end and the first inlet end of the heat pump heat exchanger, which are used for the input and output of the cold and hot solutions in the heat exchange carrier; S4, the second outlet end and the second inlet end of the heat pump heat exchanger are respectively connected to the inlet end and the outlet end of the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system to form a loop, which is used for the cold and hot energy after the pile-soil heat exchange to enter the fan coil unit and / or the floor heating system in the indoor air-conditioning circulation system to adjust the indoor temperature.

9. A heat exchange method for a ground source heat pump heat exchange system according to claim 6 or 7, characterized in that: The steps include: The hot and cold solutions from the heat pump heat exchanger flow into the inner tube of the energy pipe through the inlet end at the top of the low stress phase change energy pile. The hot and cold solutions flow in the inner tube of the energy pipe and exchange heat with the surrounding soil. Phase change material is filled between the inner tube and the outer tube of the energy tube. In summer, part of the heat of the hot solution circulating in the inner tube is stored in the phase change material between the inner tube and the outer tube. In winter, part of the coldness of the cold solution circulating in the inner tube is stored in the phase change material between the inner tube and the outer tube. Finally, the circulating solution in the inner tube of the energy tube flows back to the heat pump heat exchanger from the top outlet, completing a thermal cycle.

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