Underground station energy wall composite heat pump air conditioning system and operation method thereof

Abstract

The invention relates to an underground station energy wall composite heat pump air conditioning system and an operation method of the underground station energy wall composite heat pump air conditioning system. The tunnel area capillary heat exchanger comprises a station tunnel wall surface capillary heat exchanger, a rail top air duct capillary heat exchanger, an interval tunnel wall surface capillary heat exchanger and a piston air shaft wall surface capillary heat exchanger; the soil area capillary heat exchanger, the tunnel area capillary heat exchanger, the air conditioner end equipment and the domestic hot water tank form a plurality of heat exchange cycles with the station machine room heat pump unit through pipelines. The station hall layer capillary tube energy wall and the station bottom plate capillary tube heat exchanger exchange heat with soil, the purpose of extracting underground renewable energy for cooling and heating is achieved, tunnel waste heat is effectively recycled through the capillary tube heat exchangers arranged in the tunnel, the air duct and the piston air shaft, the temperature in the tunnel is reduced, the purpose of saving energy is achieved, and the service life of the tunnel is prolonged. And energy conservation and emission reduction of the underground station are promoted.

Description

Technical Field

[0001] The present invention relates to the technical field of energy-saving buildings, and in particular to an underground station energy wall composite heat pump air-conditioning system and an operation method thereof. Background Art

[0002] The ventilation and air-conditioning system of subway stations has a great impact on the scale and cost of station projects and the energy consumption of subway operations. It is imperative to achieve the "dual carbon" goals in the field of urban rail transit, reduce the space occupied by ventilation and air-conditioning, and reduce its energy consumption. The traditional underground station air-conditioning system is inseparable from the ground cooling tower. During the construction process, there are generally problems such as difficulty in land acquisition and layout of cooling towers, and impact on urban landscape. During the operation period, there are problems such as high energy consumption, high carbon emissions, cooling tower noise, biological contamination of water systems (Legionella), and frequent civil lawsuits caused by bleaching. In addition, in subway tunnels, equipment such as train operation and tunnel lighting will generate a lot of heat, which is usually discharged into the tunnel air, causing the temperature in the tunnel to rise, which not only affects the safe operation of the subway, but also affects the cooling efficiency of the train air-conditioning system, resulting in energy waste. In addition, the high temperature environment may affect the performance of equipment in the tunnel, resulting in an increase in the failure rate.

[0003] Therefore, it is necessary to propose new measures to overcome the above-mentioned defects. Summary of the invention

[0004] The purpose of the present invention is to provide an underground station energy wall composite heat pump air conditioning system and an operation method thereof, so as to realize tower-free cooling of the subway station air conditioning system and effectively recover the waste heat of the tunnel to achieve energy saving.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] Provided is an underground station energy wall composite heat pump air conditioning system, the system comprising a soil zone capillary heat exchanger, a tunnel zone capillary heat exchanger, a station room heat pump unit, an air conditioning terminal device and a domestic hot water tank;

[0007] The soil zone capillary heat exchanger includes a capillary energy wall and a station floor capillary heat exchanger, wherein the capillary energy wall is located on the soil side of the station hall layer, and the station floor capillary heat exchanger is located in the station floor;

[0008] The tunnel area capillary heat exchanger includes a station tunnel wall capillary heat exchanger, a rail top air duct capillary heat exchanger, a section tunnel wall capillary heat exchanger and a piston air shaft wall capillary heat exchanger;

[0009] A circulation is formed between the soil zone capillary heat exchanger and the station room heat pump unit through a pipeline;

[0010] A circulation is formed between the capillary heat exchanger in the tunnel area and the heat pump unit in the station room through a pipeline;

[0011] The air-conditioning terminal equipment and the domestic hot water tank are respectively connected to the station room heat pump unit through pipelines to form a circulation.

[0012] Furthermore, the capillary energy wall comprises an underground station structural wall, a capillary grid buried pipe layer, an insulation layer and an off-wall wall, which are arranged in sequence from the soil side to the station side, and an air interlayer is provided between the insulation layer and the off-wall wall;

[0013] The side of the thermal insulation layer close to the air interlayer is provided with an aluminum-tin film layer, and the side of the off-wall wall close to the air interlayer is provided with an aluminum-tin film layer;

[0014] The capillary grid is arranged in the capillary grid buried tube layer.

[0015] Furthermore, the station tunnel wall capillary heat exchanger includes a capillary grid laid on the inner wall of the platform layer soil side structural wall, the rail top air duct capillary heat exchanger includes a capillary grid laid on the inner bottom surface of the rail top air duct, the interval tunnel wall capillary heat exchanger includes a capillary grid laid on the inner wall of the interval tunnel, and the piston air shaft wall capillary heat exchanger includes a capillary grid laid on the inner wall of the piston air shaft, and the capillary grid is covered with a graphene composite coating;

[0016] The station floor capillary heat exchanger is a capillary grid laid in the station floor.

[0017] Furthermore, the station tunnel wall capillary heat exchanger, the rail top air duct capillary heat exchanger, the interval tunnel wall capillary heat exchanger and the piston air shaft wall capillary heat exchanger are connected in parallel, valves are respectively provided, and a first cycle is formed with the station machine room heat pump unit through pipelines;

[0018] The capillary energy wall and the station floor capillary heat exchanger are connected in parallel, valves are provided respectively, and a second cycle is formed through pipelines with the station room heat pump unit;

[0019] The air conditioning terminal equipment forms a third cycle through a valve and a pipeline with the station room heat pump unit;

[0020] The domestic hot water tank forms a fourth circulation through a valve and a pipeline with the station room heat pump unit.

[0021] Furthermore, the system also includes a constant pressure and water replenishment device, which is connected to the third cycle and the fourth cycle.

[0022] On the other hand, a method for operating an underground station energy wall composite heat pump air conditioning system is provided, the method comprising:

[0023] When there is no demand for cooling or heating in the transition season, open the valves of the first cycle and the fourth cycle, and use the capillary heat exchangers on the wall of the station tunnel, the capillary heat exchanger on the rail top duct, the capillary heat exchanger on the wall of the section tunnel and the capillary heat exchanger on the wall of the piston air shaft to extract the waste heat in the tunnel, and produce domestic hot water through heat exchange with the heat pump unit in the station machine room.

[0024] On the other hand, a method for operating an underground station energy wall composite heat pump air conditioning system is provided, the method comprising:

[0025] In summer, open the valves of the first circulation, the second circulation, the third circulation and the fourth circulation;

[0026] The circulating water of the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the heat exchange is exchanged by the heat pump unit in the station room to produce domestic hot water for the fourth cycle;

[0027] The circulating water in the second cycle exchanges heat with the soil, lowering its temperature. The cooling energy brought by it is used for heat exchange in the station room heat pump unit to provide cooling for the third cycle.

[0028] On the other hand, a method for operating an underground station energy wall composite heat pump air conditioning system is provided, the method comprising:

[0029] In winter, open the valves of the station tunnel wall capillary heat exchanger, the section tunnel wall capillary heat exchanger, and the piston air shaft capillary heat exchanger in the first cycle, the valves of the second cycle, the valves of the third cycle, and the valves of the fourth cycle;

[0030] The circulating water in the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the heat exchange of the station room heat pump unit is used to heat the third and fourth cycles;

[0031] The circulating water in the second cycle exchanges heat with the soil, and the temperature rises. The heat brought by it is exchanged through the heat pump unit in the station room to provide heat for the third and fourth cycles.

[0032] Furthermore, when the air temperature in the tunnel is less than or equal to 5°C, the valve of the capillary heat exchanger on the wall of the station tunnel and the valve of the capillary heat exchanger on the wall of the section tunnel in the first cycle are further closed.

[0033] Furthermore, the constant pressure and water replenishing devices are turned on to replenish water to the third circulation and the fourth circulation.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] The present invention provides an underground station energy wall composite heat pump air conditioning system and its operation method. In summer, the capillary energy wall at the station hall layer and the capillary heat exchanger at the station floor exchange heat with the soil to achieve the purpose of extracting underground renewable energy for cooling, replacing the traditional cooling tower, solving the current problems of large area of ​​underground station cooling tower, difficult coordination and layout, affecting the landscape and noise nuisance, eliminating the area occupied by the cooling tower, saving the initial investment in civil construction, and achieving environmental friendliness. In winter, the capillary energy wall at the station hall layer and the capillary heat exchanger at the station floor extract heat from the soil to solve the heating problem of the equipment room of the underground station in winter; and it can replace the boiler to provide domestic hot water for the surrounding buildings of the underground station. In addition, the capillary heat exchanger set in the tunnel, air duct, and piston air shaft effectively recovers the waste heat in the tunnel, reduces the temperature in the tunnel, and reduces the risk of high temperature during train operation. By recovering the waste heat, the purpose of saving energy is achieved, and energy conservation and emission reduction of underground stations are promoted. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, drawings of other embodiments can be obtained based on these drawings without paying creative work.

[0037] Figure 1 It is a system structure diagram of the present invention.

[0038] Figure 2 It is a structural diagram of the capillary energy wall of the present invention.

[0039] Figure 3 This is the layout diagram of the capillary grid in the station tunnel.

[0040] Figure 4 This is the capillary grid layout diagram of the rail top air duct.

[0041] Figure 5 This is a top-down view of the capillary grid layout of the rail top air duct.

[0042] Figure 6 This is the capillary grid layout diagram of the horseshoe-shaped interval tunnel.

[0043] Figure 7 This is the capillary grid layout diagram of the piston air shaft.

[0044] Figure 8 It is the layout diagram of the capillary grid of the station floor.

[0045] Fig. 9 It is the operation zoning map of the energy underground station.

[0046] Fig.10 It is a diagram of the working principle of the energy underground station in the transition season.

[0047] Fig.11 It is a diagram of the working principle of the energy underground station in summer.

[0048] Fig.12 This is the working principle diagram of the energy underground station in winter.

[0049] The symbols in the figure are:

[0050] 1-soil side, 2-underground station structural wall, 3-capillary mesh buried pipe layer, 4-insulation layer, 5-aluminum-tin film layer, 6-air interlayer, 7-wall-free wall, 8-station side, 9-hanger, 10-capillary mesh, 11-track top air duct, 12-graphene composite coating, 13-station tunnel, 14-platform side, 15-vehicle contour line, 16-tunnel contour line, 17-top equipment, 18-ballast bed, 19-energy underground station, 20-station hall layer, 21-platform layer, 22-station machine room heat pump unit, 23-air conditioning terminal equipment, 24-domestic hot water tank, 25-capillary energy wall, 26-soil seepage zone, 27-tunnel surrounding rock soil, 28-section tunnel. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present invention, the present invention will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present invention are given in the drawings. However, the present invention can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present invention more thoroughly understood.

[0052] In the description of the present invention, it is necessary to understand that the orientations or positional relationships indicated by the terms "top", "bottom", "inside", "outside", etc. are 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, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "connection", "setting", etc. should be understood in a broad sense, for example, it can be fixed connection, setting, or detachable connection, setting, or integral connection, setting. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0054] Meanwhile, in the description of the present invention, the terms "first", "second", etc. are only used to distinguish the description and cannot be understood as indicating or implying relative importance. Of course, such objects can be interchanged where appropriate, so that the embodiments of the present application described herein can be implemented in an order other than that illustrated or described herein.

[0055] It should also be noted that although the order of steps is mentioned in the method description, in some cases, they may be performed in an order different from that shown here, and this should not be construed as a limitation on the order of the steps.

[0056] How to achieve "tower-free cooling", how to effectively utilize the waste heat of subway tunnels, and how to improve the energy efficiency of subway stations are new directions for promoting energy conservation and emission reduction in subway stations. If these waste energy can be converted into usable clean energy, it will not only help reduce the energy consumption cost of subway operations, but also contribute to the sustainable development of the city. Soil source heat pump air conditioning systems have been widely used in civil buildings. As a typical shallow geothermal utilization system, soil source heat pumps achieve tower-free cooling and can avoid the disadvantages of using cooling towers. However, traditional soil source heat pumps usually use drilled vertical buried pipe heat exchangers as underground heat exchange elements, which occupy a large amount of land resources and have high drilling and installation costs. It is precisely because of the lack of available land resources for buried pipes that shallow vertical buried pipe soil source heat pump air conditioning systems are rarely used in subway stations. The medium-deep buried pipe technology that has emerged in recent years can solve the problem of shallow buried pipes occupying a large area of ​​land, but the medium-deep buried pipes can only take heat but not cool, and cannot solve the cooling problem of buildings.

[0057] In addition, although tunnel source heat pumps are now available to recover waste heat in tunnels, there is still a lot of space in the tunnel that can be used. How to further increase the amount of waste heat recovery and improve the efficiency of the heat pump still needs to be solved.

[0058] The present invention combines the space and structural characteristics of the subway station itself to provide an underground station energy wall composite heat pump air conditioning system, which is simple to construct, occupies a small space, is low in cost, and has strong heat exchange performance. Figure 1 The system includes a soil zone capillary heat exchanger, a tunnel zone capillary heat exchanger, a station room heat pump unit 22, an air conditioning terminal device 23 and a domestic hot water tank 24. The soil zone capillary heat exchanger includes two parts, namely a capillary energy wall 25 and a station floor capillary heat exchanger, wherein the capillary energy wall 25 is located on the soil side 1 of the station hall layer 20, and the station floor capillary heat exchanger is located in the station floor. The tunnel zone capillary heat exchanger includes four parts, including a station tunnel wall capillary heat exchanger, a rail top air duct capillary heat exchanger, a section tunnel wall capillary heat exchanger and a piston air shaft wall capillary heat exchanger.

[0059] like Figure 2The capillary energy wall 25 includes an underground station structural wall 2, a capillary grid buried pipe layer 3, an insulation layer 4 and an away wall 7, which are arranged in sequence from the soil side 1 to the station side 8, and an air interlayer 6 is provided between the insulation layer 4 and the away wall 7. In addition, an aluminum-tin film layer 5 is provided on one side of the insulation layer 4 close to the air interlayer 6, and an aluminum-tin film layer 5 is provided on one side of the away wall 7 close to the air interlayer 6. A capillary grid 10 is arranged in the capillary grid buried pipe layer 3. The composite structure design of the insulation layer 4, the air interlayer 6 and the double-layer aluminum-tin film layer on both sides of the air interlayer 6 in the capillary energy wall 25 enables the capillary energy wall 25 to perform one-way heat exchange with the soil, but will not perform heat exchange with the station side 8, effectively avoiding the influence of the heat exchange process of the capillary energy wall on the thermal environment in the station.

[0060] like Figure 8 The station floor capillary heat exchanger is located in the station floor, and is a capillary grid 10 laid in the station floor, which can exchange heat with the soil seepage zone 26 below.

[0061] like Figure 3 The station tunnel wall capillary heat exchanger includes a capillary grid 10 laid on the inner wall of the structural wall 1 on the soil side of the platform layer 21. Figure 4 The rail top air duct capillary heat exchanger includes a capillary grid 10 laid on the bottom surface of the rail top air duct 11. Figure 6 The inter-tunnel wall capillary heat exchanger includes a capillary grid 10 laid on the inner wall of the inter-tunnel 28. Figure 7 The piston air shaft wall capillary heat exchanger includes a capillary grid 10 laid on the inner wall of the piston air shaft. The capillary grids 10 of the capillary heat exchangers in the four tunnel areas are all covered with a graphene composite coating 12.

[0062] The soil zone capillary heat exchanger and the station room heat pump unit 22 form a circulation through the pipeline; the tunnel zone capillary heat exchanger and the station room heat pump unit 22 form a circulation through the pipeline; the air conditioning terminal equipment 23 and the domestic hot water tank 24 form a circulation with the station room heat pump unit 22 through the pipeline. Specifically, Fig. 9 The capillary heat exchangers on the wall of the station tunnel, the capillary heat exchangers on the rail top duct, the capillary heat exchangers on the wall of the interval tunnel and the capillary heat exchangers on the wall of the piston air shaft are connected in parallel, valves are set respectively, and the first cycle is formed through pipelines with the heat pump unit 22 in the station room; the capillary energy wall 25 is connected in parallel with the capillary heat exchanger on the station floor, valves are set respectively, and the second cycle is formed through pipelines with the heat pump unit 22 in the station room; the air conditioning terminal equipment 23 forms a third cycle through valves and pipelines with the heat pump unit 22 in the station room; the domestic hot water tank 24 forms a fourth cycle through valves and pipelines with the heat pump unit 22 in the station room. In addition, the system also includes a constant pressure and water replenishment device, which is connected to the third and fourth cycles.

[0063] like Figure 5 Each part of the capillary grid is equipped with a water supply pipeline and a return pipeline, and is connected to the corresponding circulation. In summer, the cold in the underground soil is extracted through the capillary energy wall 25 and the capillary heat exchanger on the station floor for indoor cooling, and the residual heat in the tunnel is recovered through the capillary heat exchanger in the tunnel for preparing domestic hot water. In winter, the heat in the underground soil and the tunnel is extracted through the capillary energy wall 25, the capillary heat exchanger on the station floor, and the capillary heat exchanger in the tunnel area to meet the heating needs of the underground station equipment and management rooms, and can also be used to prepare domestic hot water for the surrounding buildings of the station.

[0064] Part of this system is based on the typical wall structure of underground stations, making full use of the cavity gap between the continuous wall and the wall of the subway car, as well as the large contact area between the station floor and the soil, and laying the capillary heat exchanger on the inner surface of the structural wall and the lower surface of the station floor, forming an underground heat exchange device for the energy underground station soil source heat pump, so as to extract underground renewable energy, replace the traditional ground cooling tower in summer, and replace the boiler in winter. The other part is based on the available space in the tunnel, laying the capillary heat exchanger on the tunnel and the air duct wall to recover the waste heat in the tunnel and replace the boiler to prepare hot water for users.

[0065] The operation method of the above-mentioned underground station energy wall composite heat pump air conditioning system includes the following modes:

[0066] Mode 1: Transition Season

[0067] There is no demand for cooling or heating in the transition season. At this time, the valves of the first cycle and the fourth cycle are opened, and the capillary heat exchangers on the wall of the station tunnel, the rail top air duct, the section tunnel wall and the piston air shaft wall are used to extract the waste heat in the tunnel. Domestic hot water is produced through the station machine room heat pump unit 22 and connected to the domestic hot water tank to supply users in the buildings surrounding the station.

[0068] Mode 2: Summer

[0069] Open the valve of the first cycle, the valve of the second cycle, the valve of the third cycle and the valve of the fourth cycle;

[0070] The circulating water of the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the heat exchange is exchanged by the heat pump unit in the station room to produce domestic hot water for the fourth cycle;

[0071] The circulating water of the second cycle exchanges heat with the soil, the temperature is reduced, and the cold energy brought is exchanged through the heat pump unit 22 in the station room to provide cooling for the third cycle.

[0072] Mode 3: Winter

[0073] Open the valves of the station tunnel wall capillary heat exchanger, the section tunnel wall capillary heat exchanger, and the piston air shaft capillary heat exchanger in the first cycle, the valves of the second cycle, the valves of the third cycle, and the valves of the fourth cycle;

[0074] The circulating water in the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the heat exchange of the station room heat pump unit 22 is used to provide heat for the third and fourth cycles;

[0075] The circulating water in the second cycle exchanges heat with the soil, the temperature rises, and the heat brought by the heat pump unit 22 in the station room is used to heat the third and fourth cycles;

[0076] When the air temperature in the tunnel is less than or equal to 5°C, the valve of the capillary heat exchanger on the wall of the station tunnel and the valve of the capillary heat exchanger on the wall of the section tunnel in the first cycle are further closed.

[0077] The constant pressure and water replenishment device is used to provide initial water supply for the third and fourth circulation pipelines, and to ensure that the system pressure is stable within a certain range to prevent water from being emptied or vaporized. When the system pressure is reduced due to water loss caused by sewage discharge and system dripping, the system is replenished with water.

[0078] The air conditioning terminal device 23 is a capillary radiation terminal or an air handling unit. In some equipment rooms and management rooms, there is no indoor moisture dissipation source, and the main load is sensible heat load. Therefore, the design of the present invention adopts a capillary radiation terminal. Compared with fan coil units and all-air systems, the COP of the unit can be greatly improved. For working rooms close to underground soil, there is a risk of wall seepage, and there are sensible heat loads and latent heat loads. An independent humidity control system, such as an independent fresh air system, should be added on the basis of the capillary radiation terminal. For station halls and platform-level public areas with relatively large traffic, a traditional all-air system is used.

[0079] Based on the typical wall structure of underground stations, the characteristics of the station floor in contact with the soil, and the available space inside the tunnel, the capillary heat exchanger is laid in these structures to form an underground heat exchange device of the system. In summer, the heat discharged from the station into the cooling water is transferred to the surrounding soil to extract underground renewable energy for cooling, replacing the traditional ground cooling tower, and realizing the "tower-free cooling" of the subway station air-conditioning system. In winter, the capillary heat exchanger is used to extract the heat in the soil and tunnel to meet the heating needs of rooms such as equipment management rooms and to produce domestic hot water. In summer, the capillary heat exchanger can also be used to extract the heat in the tunnel to produce domestic hot water for the overlying buildings. The technology effectively combines the capillary heat exchanger with the structure and space of the subway station itself, replacing the traditional soil source heat pump borehole heat exchanger, solving the problems of high drilling cost and underground space occupation of the traditional borehole heat exchanger; and effectively recovering the waste heat in the subway station and tunnel, promoting energy conservation and emission reduction of the underground station air-conditioning system, and reducing the energy consumption of the overlying buildings, reducing environmental pollution, and promoting sustainable development.

[0080] Example:

[0081] The following is a further detailed description of some core components of the system of the present invention in conjunction with specific engineering examples:

[0082] The core parts of the underground station energy wall composite heat pump air-conditioning system are the capillary heat exchanger in the soil area and the capillary heat exchanger in the tunnel area.

[0083] 1. Soil zone capillary heat exchanger:

[0084] The soil zone capillary heat exchanger includes a capillary energy wall 25 and a station floor capillary heat exchanger.

[0085] (1) Capillary energy wall 25:

[0086] The capillary energy wall 25 includes an underground station structural wall 2, a capillary grid buried pipe layer 3, an insulation layer 4 and an off-wall wall 7, which are arranged in sequence from the soil side 1 to the station side 8, and an air interlayer 6 is provided between the insulation layer 4 and the off-wall wall 7. In addition, an aluminum-tin film layer 5 is provided on one side of the insulation layer 4 close to the air interlayer 6, and an aluminum-tin film layer 5 is also provided on one side of the off-wall wall 7 close to the air interlayer 6.

[0087] Specific:

[0088] 1) Underground station structural wall 2:

[0089] The underground station structural wall 2 is a commonly used reinforced concrete structure with a thickness of generally 800-1000mm. The specific construction method is in accordance with relevant construction requirements.

[0090] 2) Capillary grid buried tube layer 3:

[0091] The capillary grid buried pipe layer 3 is laid on the inner surface of the structural wall, that is, the surface of the structural wall in the direction of the station side 8. The capillary grid buried pipe layer 3 adopts the construction method of capillary net wet installation, that is, the capillary net is directly laid on the inner surface of the structural wall and fixed with pipe clamps, and finally covered with plaster. The thickness of the buried pipe layer is 30 to 50 mm.

[0092] By utilizing the high thermal conductivity of graphite, the cement mortar of the plaster layer is adjusted to an enhanced thermal conductivity cement mortar, that is, 30-50% by mass of graphite powder is used to replace the cement mortar mixed powder, and the proportion of the cement mortar mixed powder is not changed. The enhanced thermal conductivity cement mortar is obtained by mixing evenly before adding water. Since the present invention is located on the surface of the structural wall and does not need to bear stress, the influence of adding graphite powder on the mechanical properties of the buried pipe layer can be ignored.

[0093] The capillary grid is made of polypropylene random (PP-R). The capillary grid used in the design of the present invention is a different-side water supply and return type. Compared with the same-side water supply and return type grid, it has more branch pipes and a larger flow rate, so it has a larger heat exchange capacity. The parameters of the capillary grid are as follows: the width of a single capillary grid is 1000mm, the length is 600-12000mm, the main pipe diameter is 20*2mm, the branch pipe diameter is 3.5-4.5mm, and the branch pipe wall thickness is 0.5-0.8mm. The optimal tube spacing should be 20mm. Too large branch spacing will lead to a reduction in the number of branches, and the total flow rate will also be reduced accordingly, which will result in a smaller heat exchange capacity. Although a smaller tube spacing means a larger flow rate, if the tube spacing is too small, there will be strong thermal interference between adjacent branches, resulting in a reduced heat exchange temperature difference and a reduced heat exchange capacity. The optimal water flow rate in the branch pipe is 0.05-0.13 m / s. At low flow rates (less than 0.05 m / s), the circulating water in the branch pipe is fully heat-exchanged, and the heat exchange capacity of the mesh screen is significantly increased with the increase of flow rate. At intermediate flow rates (0.05-0.13 m / s), the increase in flow rate begins to affect the heat exchange effect of the circulating water. When the flow rate of the branch pipe increases, the growth trend of the heat exchange capacity gradually slows down until high flow rates (greater than 0.13 m / s), when the heat exchange capacity of the mesh screen almost no longer increases when the flow rate in the branch pipe increases.

[0094] Each capillary grid is connected in parallel to the water supply and return pipes. This connection method ensures that each grid has a consistent water inlet temperature, which helps to evenly exchange heat. The water supply and return headers of each grid are connected by hot melt.

[0095] 3) Insulation layer 4:

[0096] In order to effectively block the heat exchange between the capillary heat exchanger and the station side 8 and prevent the heat carried by the cooling water system from being transferred into the station, the present invention lays an insulation layer 4 on the station side of the capillary grid buried pipe layer 3. The thermal insulation material is polyurethane (PU) or extruded board (extruded polystyrene foam board, XPS), and the optimal insulation layer thickness is 80 mm, which is obtained through simulation research. The reason for selecting PU and XPS is that both have good thermal insulation performance and hydrophobic and moisture-proof properties. A smooth aluminum-tin film with low emissivity is laid on the cavity side surface of the insulation layer 4. The emissivity of the aluminum-tin film is close to 0, which can reduce the radiation heat exchange between the surface of the insulation layer and the surface of the opposite wall. The use of a smooth aluminum-tin film can reduce the convective heat transfer coefficient on the inner side of the insulation layer to reduce the convective heat transfer.

[0097] 4) Air layer 6:

[0098] The air interlayer 6 (cavity) exists between the insulation layer 4 and the wall 7, and is a layer of space used by the underground station to isolate the indoor environment from the surrounding environment. In the present invention, the air interlayer 6 acts as a waterproof layer and a second layer of insulation material of the capillary energy wall 25, and its thickness is 100-250mm. Its function is to prevent groundwater from penetrating into the interior of the station and to prevent the heat in the buried pipe layer from being transferred to the station side. When the capillary energy wall 25 is located in the public area of ​​the station, the cavity thickness is 200-250mm. When the capillary energy wall 25 is located in the equipment and management room of the station, the cavity thickness is 100-150mm.

[0099] 5) Away wall 7:

[0100] The wall 7 is also a moisture-proof wall, which is used to eliminate and reduce the impact of water leakage from the outer wall on the use and aesthetics of the station's internal space. In the present invention, the wall 7 is made of fiber cement board with a thickness of 50-100 mm. The inner surface of the cavity side of the wall 7 is sprayed with a low-emissivity coating or a low-emissivity smooth aluminum-tin film is laid, and the coating surface is smoothed to reduce the radiation heat exchange between the inner surface of the cavity side of the wall 7 and other surfaces and the convection heat exchange between the inner surface and the air in the cavity, thereby reducing the heat transfer from the buried pipe layer to the station.

[0101] (2) Station floor capillary heat exchanger:

[0102] The soil temperature is stable all year round, and the station floor is buried deep, with a large contact area with the soil, and is close to the groundwater seepage zone. The present invention proposes to use the station floor as a heat exchanger carrier and design a capillary heat exchanger on the lower surface of the floor to exchange heat with the surrounding soil and groundwater. Figure 8 The presence of groundwater not only enables better convective heat transfer, but also effectively prevents heat accumulation to extract cold in summer and heat in winter.

[0103] After the foundation pit is dug during construction, capillary mesh should be laid on the bottom surface before pouring the station floor, and then a 50mm thick concrete layer should be poured as the buried pipe layer. During pouring, mesh cloth should be used to prevent cracking. Subsequent construction will then be carried out.

[0104] 2. Capillary heat exchanger in tunnel area:

[0105] When the train runs in the tunnel inside the station, a lot of heat will be generated by the operation of the motor, the braking system, and the lighting devices. Especially in summer or during high temperature periods, in order to maintain a comfortable temperature in the car, turning on the air conditioning and cooling will also generate a lot of condensation heat. Therefore, the temperature in the station tunnel is high all year round, with a minimum of about 18°C ​​in winter and a maximum of about 34°C in summer. In order to prevent the adverse effect of excessive temperature on the station, a rail top air duct 11 is usually set in the tunnel inside the station to connect with the outside world to remove this heat to ensure that the temperature in the tunnel is no higher than 40°C. This embodiment uses the available space inside the tunnel to set a capillary heat exchanger to recover the waste heat in the tunnel.

[0106] The capillary heat exchangers in the tunnel area include the station tunnel wall capillary heat exchanger, the rail top air duct capillary heat exchanger, the section tunnel wall capillary heat exchanger and the piston air shaft wall capillary heat exchanger.

[0107] (1) Station tunnel wall capillary heat exchanger:

[0108] The wall of the tunnel inside the station is flat, and grooves are cut on its surface, or space is reserved when the wall is poured, with a depth of 1 / 2 of the pipe diameter, so that the capillary tube is exposed to the high-temperature air in the tunnel to ensure the most favorable convective heat transfer.

[0109] In order to further enhance the heat conduction process and take anti-corrosion measures on the pipeline surface, a graphene composite material was cold-sprayed on the pipeline surface. It is mainly composed of graphene, graphite powder and epoxy resin. The thermal conductivity of graphene is 5300W / (m·K). Depending on the content of graphene, the thermal conductivity of the composite material is about 5-40W / (m·K), which can reach up to 100 times the thermal conductivity of the capillary. In addition, the material is corrosion-resistant and not easy to fall off. After spraying, it is consistent with the color of the wall, ensuring the beauty of the wall.

[0110] Air is a poor thermal conductor with a thermal conductivity of approximately 0.026W / (m·K). Cold spraying technology can effectively remove air, reduce material porosity, and increase coating density. Therefore, cold spraying technology helps to improve the thermal conductivity of the coating.

[0111] (2) Rail-top duct capillary heat exchanger:

[0112] Since the construction space in the tunnel is small, the quality of the rail-top air duct cannot be guaranteed during the secondary pouring process, so prefabricated and assembled rail-top air ducts are widely used. The present invention designs a capillary tube on the upper surface of the bottom plate of the rail-top air duct as a capillary heat exchanger for the rail-top air duct. When prefabricating the rail-top air duct, a pipe slot should be reserved, and then the capillary tube is fixed in the bottom plate slot. The pipe is exposed to the air, and the surface is sprayed with graphene composite materials. This surface embedded pipe method will not affect the load-bearing structure of the rail-top air duct.

[0113] (3) Capillary heat exchanger on the wall of the interval tunnel:

[0114] The lower part of the subway tunnel is the subway sleeper and roadbed, and the upper part is generally equipped with fire hoses, lighting and other equipment. Therefore, a capillary heat exchanger is set in the side wall space, and the capillary is embedded in the wall surface by slotting, and the surface is sprayed with graphene composite materials.

[0115] (4) Piston air well capillary heat exchanger:

[0116] Piston air shafts are generally located at both ends of the tunnel, and are used in conjunction with fans to provide normal ventilation or emergency ventilation for the tunnel. Taking the piston air shaft on one side of the interval tunnel as a reference, when a train approaches, the high-temperature air in the tunnel is squeezed and discharged from the piston air shaft, and negative pressure is formed inside the tunnel. The air shaft on the other side inhales low-temperature air from the outside to maintain the pressure balance of the tunnel, which is the "piston effect".

[0117] Since the inner wall of the piston air shaft is flat and has no additional equipment, the capillary is laid on the piston air shaft wall. A groove is made on the piston air shaft wall to embed the capillary in the piston air shaft wall, one side of the capillary is exposed to the air, and the surface is sprayed with graphene composite materials.

[0118] According to the needs of heating, air conditioning and domestic hot water for station buildings and overlying buildings, this system can extract cold from the soil for indoor cooling, and can also extract heat from the soil for indoor heating or preparation of domestic hot water. In addition, it can also recover waste heat in the tunnel for indoor heating or preparation of domestic hot water. According to the different temperature characteristics of the tunnel air and soil media around the heat exchanger, the capillary heat exchanger can be divided into two parts. One part is the tunnel area heat exchanger that can only extract waste heat in the tunnel, and the other part is the soil area heat exchanger that can extract both heat and cold from the soil according to user needs. Therefore, based on seasonal user needs, the system operation mode can be divided into the following three types:

[0119] 1) Transition Season

[0120] In the transition season, there is no demand for cooling or heating in the station, and the waste heat in the tunnel can be recovered to prepare domestic hot water for users in the station or surrounding buildings. Fig.10As shown, the constant pressure and water replenishment device is used to provide initial water supply for the third and fourth circulation pipelines, and to ensure that the system pressure is stable within a certain range to prevent water emptying or water vaporization. When the system pressure is reduced due to water loss caused by sewage discharge and system dripping, the system needs to be replenished with water. Valves 1 to 4 and 7 are opened, and the capillary heat exchanger in the tunnel area is used to extract the waste heat in the tunnel. The heat pump unit replaces the gas boiler to produce domestic hot water at 55 to 60°C, which is connected to the domestic hot water tank and finally supplied to the user side.

[0121] 2) Summer

[0122] In summer, the temperature in the tunnel is the highest in the year, reaching 34°C, while the temperature in the soil area is lower than the outside temperature, only about 16°C. Due to the diversity of heat exchangers in energy underground stations, the system can simultaneously extract soil cold energy for station cooling and extract tunnel waste heat to prepare hot water for regional users. When the system is running, all valves are opened, and the heat exchanger in the tunnel area and the heat exchanger in the soil area (instead of the cooling tower) are opened at the same time. Fig.11 As shown. The low-temperature hot water of 15-25℃ enters the capillary heat exchanger in the tunnel area (instead of the boiler) to extract the waste heat in the tunnel, and then the temperature rises. The heat is extracted in the evaporator of the heat pump unit, and then the refrigerant in the condenser condenses the heat and releases it to the hot water pipeline on the user side. For the soil area, the cooling water at 35℃ enters the capillary heat exchanger in the soil area (instead of the cooling tower) to exchange heat with the surrounding low-temperature soil. After the temperature is reduced, it enters the condenser of the heat pump unit to release the cold to the refrigerant, and then uses the evaporator to release the cold to the chilled water pipeline, and finally transmits it to the radiation terminal and the air handling unit to provide cooling for the equipment room and the public area of ​​the station respectively.

[0123] 3) Winter

[0124] In winter, there is less residual heat in the tunnel, which makes it difficult to meet the needs of domestic hot water and user-side radiant heating at the same time. Excessive extraction of residual heat in the tunnel may have an adverse effect on station operation. For example, if the air temperature in the tunnel is too low, the water supply pipe may be at risk of freezing and cracking. The soil zone heat exchanger can also extract heat from the soil to achieve thermal balance with the heat injection in summer to avoid heat accumulation in the soil. Therefore, when the system is running in winter, valves 1, 3, 4, 5, 6, 7, and 8 should be opened. Fig.12 As shown, it corresponds to the station tunnel wall capillary heat exchanger, the section tunnel wall capillary heat exchanger, the piston air shaft capillary heat exchanger, the soil area capillary heat exchanger and the air conditioning terminal. When the air temperature in the tunnel is less than or equal to 5°C, valves 1 and 3 are closed, and the station tunnel wall capillary heat exchanger and the section tunnel wall capillary heat exchanger stop running.

[0125] The system and method have the following technical advantages:

[0126] (1) The present invention realizes the extraction of underground renewable energy for cooling by laying capillary heat exchangers on the inner surface of the station structure wall and the station floor, which can reduce or replace the traditional cooling tower. It solves the current problems of underground station cooling towers occupying a large area, difficult coordination and layout, affecting the landscape and causing noise nuisance to residents, saves the area occupied by cooling towers, saves the initial investment in civil engineering, and achieves environmental friendliness.

[0127] (2) The capillary heat exchanger installed in the tunnel and the air duct in the present invention effectively recovers the waste heat in the tunnel, reduces the temperature in the tunnel, and reduces the risk of high temperature during train operation. By recovering the waste heat, energy is saved and energy conservation and emission reduction in underground stations are promoted.

[0128] (3) The design concept of combining the capillary heat exchanger proposed in the present invention with the supporting structure of the underground station can effectively reduce the space occupied by the underground heat exchanger and maximize the utilization of the building space.

[0129] (4) The underground station energy wall composite heat pump air conditioning system provided by the present invention can extract cold energy from the soil and waste heat from the tunnel in summer, and can simultaneously realize cooling in the station and preparing domestic hot water. In winter, heat can be extracted from the soil and tunnel, which can solve the heating problem of the management room of the underground station in winter, and can also prepare domestic hot water for the surrounding and overlying buildings of the station.

[0130] (5) The capillary heat exchangers in the present invention are independent of the internal structure of the wall and do not affect the mechanical properties of the enclosure structure. In addition, the construction is simple, and compared with the traditional energy underground structure that lays the buried pipe inside the structure, the construction difficulty is extremely low.

[0131] (6) The capillary energy wall proposed in the present invention has good insulation measures to ensure one-way heat exchange from the capillary energy wall to the soil side, so that the heat exchange process of the system will not affect the thermal environment in the station.

[0132] (7) The present invention proposes to use a surface capillary heat exchanger to replace the traditional large-diameter buried tube heat exchanger, which saves layout space, achieves a more uniform heat exchange area, saves the cost of the heat spreader, and has lower noise.

[0133] (8) The seasonal operation scheme of the composite heat pump combining the soil source heat pump and the tunnel air source heat pump proposed in the present invention greatly improves the energy utilization efficiency, operates rationally, and saves air conditioning energy consumption.

[0134] The above specific examples are used to illustrate the present invention, which is only used to help understand the present invention and is not intended to limit the present invention. For those skilled in the art, according to the concept of the present invention, some simple deductions, modifications or substitutions can be made.

Claims

1. An underground station energy wall composite heat pump air conditioning system, characterized by: The system comprises a soil zone capillary heat exchanger, a tunnel zone capillary heat exchanger, a station room heat pump unit (22), an air conditioning terminal device (23) and a domestic hot water tank (24); The soil zone capillary heat exchanger comprises a capillary energy wall (25) and a station floor capillary heat exchanger, wherein the capillary energy wall (25) is located on the soil side (1) of the station hall layer (20), and the station floor capillary heat exchanger is located in the station floor; The tunnel area capillary heat exchanger includes a station tunnel wall capillary heat exchanger, a rail top air duct capillary heat exchanger, a section tunnel wall capillary heat exchanger and a piston air shaft wall capillary heat exchanger; A circulation is formed between the soil zone capillary heat exchanger and the station room heat pump unit (22) through a pipeline; A circulation is formed between the capillary heat exchanger in the tunnel area and the heat pump unit (22) in the station room through a pipeline; The air-conditioning terminal equipment (23) and the domestic hot water tank (24) are respectively connected to the station room heat pump unit (22) through pipelines to form a circulation.

2. The underground station energy wall composite heat pump air conditioning system according to claim 1 is characterized by: The capillary energy wall (25) comprises an underground station structural wall (2), a capillary grid buried pipe layer (3), a thermal insulation layer (4) and an isolated wall (7), which are arranged in sequence from the soil side (1) to the station side (8), and an air interlayer (6) is provided between the thermal insulation layer (4) and the isolated wall (7); The side of the thermal insulation layer (4) close to the air interlayer (6) is provided with an aluminum-tin film layer (5), and the side of the separation wall (7) close to the air interlayer (6) is provided with an aluminum-tin film layer (5); A capillary grid (10) is arranged inside the capillary grid buried tube layer (3).

3. The underground station energy wall composite heat pump air conditioning system according to claim 2 is characterized by: The station tunnel wall capillary heat exchanger comprises a capillary grid (10) laid on the inner wall of the structural wall on the soil side (1) of the platform layer (21); the rail top air duct capillary heat exchanger comprises a capillary grid (10) laid on the inner bottom surface of the rail top air duct (11); the section tunnel wall capillary heat exchanger comprises a capillary grid (10) laid on the inner wall of the section tunnel (28); the piston air shaft wall capillary heat exchanger comprises a capillary grid (10) laid on the inner wall of the piston air shaft, and the capillary grid (10) is covered with a graphene composite coating (12); The station floor capillary heat exchanger is a capillary grid (10) laid in the station floor.

4. The underground station energy wall composite heat pump air conditioning system according to claim 3 is characterized by: The station tunnel wall capillary heat exchanger, the rail top air duct capillary heat exchanger, the section tunnel wall capillary heat exchanger and the piston air shaft wall capillary heat exchanger are connected in parallel, valves are provided respectively, and a first circulation is formed with the station machine room heat pump unit (22) through pipelines; The capillary energy wall (25) and the station floor capillary heat exchanger are connected in parallel, valves are provided respectively, and a second circulation is formed between the capillary energy wall (25) and the station room heat pump unit (22) through a pipeline; The air conditioning terminal device (23) forms a third cycle through a valve and a pipeline with the station room heat pump unit (22); The domestic hot water tank (24) forms a fourth circulation through a valve and a pipeline with the station room heat pump unit (22).

5. The underground station energy wall composite heat pump air conditioning system according to claim 4 is characterized by: The system also includes a constant pressure and water replenishment device connected to the third cycle and the fourth cycle.

6. The operating method of the underground station energy wall composite heat pump air conditioning system according to claim 5, characterized in that: The method comprises: When there is no demand for cooling or heating in the transition season, the valves of the first cycle and the fourth cycle are opened, and the residual heat in the tunnel is extracted by using the capillary heat exchanger on the wall of the station tunnel, the capillary heat exchanger on the rail top air duct, the capillary heat exchanger on the wall of the section tunnel and the capillary heat exchanger on the wall of the piston air shaft, and then heat is exchanged through the station machine room heat pump unit (22) to produce domestic hot water.

7. The operating method of the underground station energy wall composite heat pump air conditioning system according to claim 5, characterized in that: The method comprises: In summer, open the valves of the first circulation, the second circulation, the third circulation and the fourth circulation; The circulating water of the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the heat exchange is exchanged by the heat pump unit in the station room to produce domestic hot water for the fourth cycle; The circulating water of the second cycle exchanges heat with the soil, the temperature is reduced, and the cold energy brought is exchanged with the station room heat pump unit (22) to provide cooling for the third cycle.

8. The operating method of the underground station energy wall composite heat pump air conditioning system according to claim 5, characterized in that: The method comprises: In winter, open the valves of the station tunnel wall capillary heat exchanger, the section tunnel wall capillary heat exchanger, and the piston air shaft capillary heat exchanger in the first cycle, the valves of the second cycle, the valves of the third cycle, and the valves of the fourth cycle; The circulating water in the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by the water is exchanged with the station room heat pump unit (22) to provide heat for the third and fourth cycles. The circulating water in the second cycle exchanges heat with the soil, and the temperature rises. The heat brought by the heat exchange is used by the station room heat pump unit (22) to provide heat for the third and fourth cycles.

9. The method for operating the underground station energy wall composite heat pump air conditioning system according to claim 8, characterized in that: When the air temperature in the tunnel is less than or equal to 5°C, the valve of the capillary heat exchanger on the wall of the station tunnel and the valve of the capillary heat exchanger on the wall of the section tunnel in the first cycle are further closed.

10. The operating method of the underground station energy wall composite heat pump air conditioning system according to claim 6 or 7, characterized in that: Open the constant pressure and water replenishing device to replenish water to the third circulation and the fourth circulation.

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