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

Abstract

The present application relates to a kind of underground station energy wall composite heat pump air conditioning system and its operating method, in the system, soil area capillary heat exchanger includes capillary energy wall and station floor capillary heat exchanger, tunnel area capillary heat exchanger includes station tunnel wall surface capillary heat exchanger, track top air duct capillary heat exchanger, section tunnel wall surface capillary heat exchanger and piston air shaft wall surface capillary heat exchanger;Soil area capillary heat exchanger, tunnel area capillary heat exchanger, air conditioning terminal equipment and domestic hot water tank are respectively connected with station machine room heat pump unit by pipeline and form multiple heat exchange cycles.The present application exchanges heat with soil by station hall capillary energy wall and station floor capillary heat exchanger, realizes the purpose of extracting underground renewable energy for cooling and heating, and effectively recovers tunnel waste heat by capillary heat exchanger arranged in tunnel, air duct and piston air shaft, reduces temperature in tunnel, achieves the purpose of energy saving, promotes energy saving and emission reduction of underground station.

Description

Technical Field

[0001] This invention relates to the field of energy-saving building technology, specifically to an underground station energy wall composite heat pump air conditioning system and its operation method. Background Technology

[0002] The ventilation and air conditioning system of subway stations has a significant impact on the scale and cost of station projects and the energy consumption of subway operation. To achieve the "dual carbon" goals in urban rail transit, reducing the space occupied by ventilation and air conditioning systems and lowering their energy consumption is imperative. Traditional underground station air conditioning systems rely heavily on surface cooling towers. During construction, problems commonly arise such as difficulties in land acquisition and placement of cooling towers, and their impact on the urban landscape. During operation, issues include high energy consumption, high carbon emissions, cooling tower noise, biological pollution of water systems (Legionella), and frequent civil lawsuits caused by drift. Furthermore, in subway tunnels, train operation and tunnel lighting equipment generate a large amount of heat, which is usually released into the tunnel air, causing the tunnel temperature to rise. This not only affects the safe operation of the subway but also reduces the cooling efficiency of the train's air conditioning system, resulting in energy waste. High-temperature environments can also affect the performance of equipment within the tunnel, leading to an increased failure rate.

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

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

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A composite heat pump air conditioning system for an underground station is provided, the system comprising a capillary heat exchanger in the soil zone, a capillary heat exchanger in the tunnel zone, a heat pump unit in the station equipment room, air conditioning terminal equipment, and a domestic hot water tank;

[0007] The soil capillary heat exchanger includes a capillary energy wall and a station floor capillary heat exchanger. The capillary energy wall is located on the soil side of the station hall level, and the station floor capillary heat exchanger is located inside the station floor.

[0008] The capillary heat exchangers in the tunnel area include capillary heat exchangers on the station tunnel walls, capillary heat exchangers on the track top ventilation ducts, capillary heat exchangers on the tunnel walls in the intervals, and capillary heat exchangers on the walls of the piston ventilation shafts.

[0009] The soil capillary heat exchanger and the station machine room heat pump unit form a circulation through pipelines;

[0010] The tunnel area capillary heat exchanger and the station machine room heat pump unit form a circulation through pipes;

[0011] The air conditioner terminal equipment and the domestic hot water tank are respectively connected with the station machine room heat pump unit through pipes to form a circulation.

[0012] Further, the capillary energy wall comprises an underground station structure wall, a capillary grid buried pipe layer, an insulation layer and a detached wall, which are arranged in sequence from the soil side to the station side, and the insulation layer and the detached wall have an air interlayer therebetween;

[0013] One side of the insulation layer close to the air interlayer is provided with an aluminum-tin film layer, and one side of the detached 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 pipe layer.

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

[0016] The station tunnel wall capillary heat exchanger comprises a capillary grid arranged on the inner wall surface of the structure wall on the soil side of the platform layer, the rail top air duct capillary heat exchanger comprises a capillary grid arranged on the bottom surface of the rail top air duct, the interval tunnel wall capillary heat exchanger comprises a capillary grid arranged on the inner wall of the interval tunnel, and the piston air shaft wall capillary heat exchanger comprises a capillary grid arranged on the inner wall of the piston air shaft, and the capillary grid is covered with a graphene composite coating;

[0017] Further, 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 with each other, respectively provided with valves, and form a first circulation with the station machine room heat pump unit through pipes;

[0018] The capillary energy wall and the station tunnel wall capillary heat exchanger are connected in parallel with each other, respectively provided with valves, and form a second circulation with the station machine room heat pump unit through pipes;

[0019] The air conditioner terminal equipment is connected with the station machine room heat pump unit through pipes to form a third circulation through a valve.

[0020] The domestic hot water tank is connected with the station machine room heat pump unit through pipes to form a fourth circulation through a valve.

[0021] Further, the system further comprises a constant pressure and water supplement device connected to the third circulation and the fourth circulation.

[0022] In another aspect, provided is a method for operating an energy wall composite heat pump air conditioning system of an underground station, the method comprising:

[0023] When there is no cooling or heating demand in the transition season, the valves of the first cycle and the fourth cycle are opened, the residual heat in the tunnel is extracted by the tunnel wall capillary heat exchanger, the track top air duct capillary heat exchanger, the interval tunnel wall capillary heat exchanger and the piston air shaft wall capillary heat exchanger, and the hot water is prepared by the heat exchange of the station machine room heat pump unit.

[0024] In another aspect, provided is a method for operating an energy wall composite heat pump air conditioning system of an underground station, the method comprising:

[0025] In summer, the valves of the first cycle, the second cycle, the third cycle and the fourth cycle are opened.

[0026] The circulating water of the first cycle extracts the residual heat in the tunnel, the temperature is increased, and the heat is brought to the heat exchange of the station machine room heat pump unit to prepare the hot water for the fourth cycle.

[0027] The circulating water of the second cycle exchanges heat with the soil, the temperature is decreased, and the cold is brought to the heat exchange of the station machine room heat pump unit to provide cooling for the third cycle.

[0028] In another aspect, provided is a method for operating an energy wall composite heat pump air conditioning system of an underground station, the method comprising:

[0029] In winter, the valves of the station tunnel wall capillary heat exchanger, the interval tunnel wall capillary heat exchanger and the piston air shaft capillary heat exchanger in the first cycle, the valves of the second cycle, the third cycle and the fourth cycle are opened.

[0030] The circulating water of the first cycle extracts the residual heat in the tunnel, the temperature is increased, and the heat is brought to the heat exchange of the station machine room heat pump unit to provide heat for the third cycle and the fourth cycle.

[0031] The circulating water of the second cycle exchanges heat with the soil, the temperature is increased, and the heat is brought to the heat exchange of the station machine room heat pump unit to provide heat for the third cycle and the fourth cycle.

[0032] Further, when the air temperature in the tunnel is less than or equal to 5℃, the valves of the station tunnel wall capillary heat exchanger and the interval tunnel wall capillary heat exchanger in the first cycle are further closed.

[0033] Further, the constant pressure and water supplement device is opened to supplement water to the third cycle and the fourth cycle.

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

[0035] The application provides an underground station energy wall composite heat pump air conditioning system and a running method thereof. BRIEF DESCRIPTION OF DRAWINGS

[0036] In order to more clearly illustrate the technical solutions in the embodiments of the present application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced. Obviously, the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings of other embodiments can be obtained without creative labor on the basis of these drawings.

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

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

[0039] Figure 3 It is a capillary grid layout diagram in a station tunnel.

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

[0041] Figure 5 It is a capillary grid layout diagram of a rail top air duct.

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

[0043] Figure 7 It is a capillary grid layout diagram of a piston air shaft.

[0044] Figure 8 It is a capillary grid layout diagram of a station bottom plate.

[0045] Figure 9 It is a running partition diagram of an energy underground station.

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

[0047] Figure 11 is the working principle diagram of the energy underground station in the summer season.

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

[0049] Identified in the figure as:

[0050] 1-soil side, 2-underground station structure wall, 3-capillary network grid buried pipe layer, 4-thermal insulation layer, 5-aluminum tin film layer, 6-air interlayer, 7-off-wall, 8-station side, 9-hanging rib, 10-capillary network grid, 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-track bed, 19-energy underground station, 20-station hall layer, 21-station platform layer, 22-station room heat pump unit, 23-air conditioning terminal equipment, 24-living hot water tank, 25-capillary energy wall, 26-soil seepage area, 27-tunnel surrounding rock soil, 28-interval tunnel. DETAILED DESCRIPTION

[0051] In order to facilitate the understanding of the present application, the present application will be described in more detail below with reference to the relevant drawings. The preferred embodiments of the present application are shown in the drawings. However, the present application can be realized 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 application more thorough and comprehensive.

[0052] In the description of the present application, it should be understood that the terms "top", "bottom", "inner", "outer" and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the purpose of facilitating the description of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the device or element referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application.

[0053] In the description of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "provided" and the like should be understood broadly, for example, it can be fixedly connected, provided, or detachably connected, provided, or integrally connected, provided. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0054] Furthermore, in the description of this invention, the terms "first," "second," etc., are used only for distinguishing descriptions and should not be construed as indicating or implying relative importance. Of course, such terms can be interchanged where appropriate so that the embodiments of this application described herein can be implemented in a sequence other than those 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, steps may be performed in a different order than that described here, and this should not be interpreted as a restriction on the order of steps.

[0056] Achieving "towerless cooling" and effectively utilizing waste heat from subway tunnels to improve the energy efficiency of subway stations are new directions for promoting energy conservation and emission reduction in subway stations. If this waste energy can be converted into usable clean energy, it will not only help reduce the energy costs of subway operation but also contribute to the sustainable development of cities. Soil source heat pump air conditioning systems are widely used in civil buildings. As a typical shallow geothermal utilization system, soil source heat pumps achieve towerless cooling, avoiding the drawbacks of using cooling towers. However, traditional soil source heat pumps typically use drilled vertical buried pipe heat exchangers as underground heat exchange elements, occupying a large amount of land resources, and the drilling installation cost is high. It is precisely because of the lack of usable land resources for buried pipes that shallow vertical buried pipe soil source heat pump air conditioning systems are rarely used in subway stations. In recent years, medium-deep buried pipe technology has emerged, which can solve the problem of large land area occupation by shallow buried pipes, but medium-deep buried pipes can only extract heat and not cool, failing to solve the building's cooling problem.

[0057] In addition, although tunnel-source heat pumps have emerged to recover waste heat in tunnels, there is still a lot of space available in tunnels. How to further increase the amount of waste heat recovered and improve the efficiency of heat pumps still needs to be addressed.

[0058] This invention provides a composite heat pump air conditioning system for underground stations, taking into account the spatial and structural characteristics of subway stations. It features simple construction, small footprint, low cost, and strong heat exchange performance. Specifically, for example... Figure 1 The system includes a soil zone capillary heat exchanger, a tunnel zone capillary heat exchanger, a station machine room heat pump unit 22, air conditioning terminal equipment 23, and a domestic hot water tank 24. The soil zone capillary heat exchanger comprises two parts: a capillary energy wall 25 and a station floor capillary heat exchanger. The capillary energy wall 25 is located on the soil side 1 of the concourse level 20, and the station floor capillary heat exchanger is located within the station floor. The tunnel zone capillary heat exchanger comprises four parts: a station tunnel wall capillary heat exchanger, a track top ventilation duct capillary heat exchanger, an inter-tunnel wall capillary heat exchanger, and a piston ventilation shaft wall capillary heat exchanger.

[0059] like Figure 2, the capillary energy wall 25 comprises the underground station structure wall 2, the capillary grid buried pipe layer 3, the heat preservation layer 4 and the off-wall wall 7, which are arranged in sequence from the soil side 1 to the station side 8, and the air interlayer 6 is arranged between the heat preservation layer 4 and the off-wall wall 7. In addition, the heat preservation layer 4 is provided with the aluminum-tin film layer 5 on the side close to the air interlayer 6, and the off-wall wall 7 is provided with the aluminum-tin film layer 5 on the side close to the air interlayer 6. The capillary grid 10 is arranged in the capillary grid buried pipe layer 3. The composite structure design of the heat preservation layer 4, the air interlayer 6 and the double aluminum-tin film layers on the two sides of the air interlayer 6 in the capillary energy wall 25 makes the capillary energy wall 25 capable of carrying out one-way heat exchange with the soil, but not with the station side 8, thereby effectively avoiding the influence of the heat exchange process of the capillary energy wall on the thermal environment in the station.

[0060] As shown in Figure 8 , the station bottom plate capillary heat exchanger is arranged in the station bottom plate and can carry out heat exchange with the soil seepage area 26 below for the capillary grid 10 laid in the station bottom plate.

[0061] As shown in Figure 3 , the station tunnel wall surface capillary heat exchanger comprises the capillary grid 10 laid on the inner wall surface of the structure wall in the soil side 1 of the platform layer 21. Figure 4 , the rail top air duct capillary heat exchanger comprises the capillary grid 10 laid on the bottom surface of the rail top air duct 11. Figure 6 , the interval tunnel wall surface capillary heat exchanger comprises the capillary grid 10 laid on the inner wall of the interval tunnel 28. Figure 7 , the piston air shaft wall surface capillary heat exchanger comprises the capillary grid 10 laid on the inner wall of the piston air shaft. The capillary grid 10 of the above four parts of tunnel area capillary heat exchangers is covered with the graphene composite coating 12.

[0062] The soil area capillary heat exchanger and the station machine room heat pump unit 22 form a circulation through a pipeline; the tunnel area capillary heat exchanger and the station machine room heat pump unit 22 form a circulation through a pipeline; the air conditioning terminal equipment 23 and the domestic hot water tank 24 respectively form a circulation with the station machine room heat pump unit 22 through a pipeline. Specifically, Figure 9 , the station tunnel wall surface capillary heat exchanger, the rail top air duct capillary heat exchanger, the interval tunnel wall surface capillary heat exchanger and the piston air shaft wall surface capillary heat exchanger are connected in parallel with each other, respectively provided with valves and form a first circulation with the station machine room heat pump unit 22 through a pipeline; the capillary energy wall 25 and the station bottom plate capillary heat exchanger are connected in parallel with each other, respectively provided with valves and form a second circulation with the station machine room heat pump unit 22 through a pipeline; the air conditioning terminal equipment 23 and the station machine room heat pump unit 22 form a third circulation through a pipeline through a valve; the domestic hot water tank 24 and the station machine room heat pump unit 22 form a fourth circulation through a pipeline through a valve. In addition, the system further comprises a constant pressure and water supplement device connected to the third circulation and the fourth circulation.

[0063] As Figure 5 , each part of the capillary grid is configured with a water supply pipeline and a return pipeline, and is connected to the corresponding cycle. In summer, the cold energy in the underground soil is extracted by the capillary energy wall 25 and the station floor capillary heat exchanger for indoor cooling, and the tunnel heat is recovered by 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 by the capillary energy wall 25, the station floor capillary heat exchanger and the tunnel area capillary heat exchanger to meet the heating demand of the underground station equipment and management room, and can also be used to prepare domestic hot water for the overlying buildings around the station.

[0064] Part of the system is based on the typical off-wall structure of the underground station, fully utilizes the cavity gap between the subway continuous wall and the off-wall, and the large contact area between the station floor and the soil, and the capillary heat exchanger is laid on the inner surface of the structural wall and the lower surface of the station floor to form the underground heat exchange device of the energy underground station soil source heat pump, so as to extract the underground renewable energy, replace the traditional ground cooling tower in summer and replace the boiler in winter. Another part is based on the available space in the tunnel, and the capillary heat exchanger is laid on the tunnel and 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 one: transition season

[0067] There is no cooling or heating demand in the transition season, at this time, the valves of the first cycle and the fourth cycle are opened, and the tunnel wall capillary heat exchanger, the track top air duct capillary heat exchanger, the interval tunnel wall capillary heat exchanger and the piston air shaft wall capillary heat exchanger are used to extract the waste heat in the tunnel, and the station machine room heat pump unit 22 is used to prepare domestic hot water, which is connected to the domestic hot water tank to supply users of the overlying buildings around the station.

[0068] Mode two: summer

[0069] The valves of the first cycle, the second cycle, the third cycle and the fourth cycle are opened.

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

[0071] The circulating water of the second cycle exchanges heat with the soil, the temperature decreases, and the cold energy brought by the heat exchange of the station machine room heat pump unit 22 is used to supply cooling for the third cycle.

[0072] Mode three: winter

[0073] opening 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 and 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, the temperature is increased, and the heat brought by the heat exchange of the station machine room heat pump unit 22 is used for heating the third cycle and the fourth cycle;

[0075] The circulating water in the second cycle exchanges heat with the soil, the temperature is increased, and the heat brought by the heat exchange of the station machine room heat pump unit 22 is used for heating the third cycle and the fourth cycle;

[0076] When the air temperature in the tunnel is less than or equal to 5℃, further closing the valves of the station tunnel wall capillary heat exchanger and the valves of the section tunnel wall capillary heat exchanger in the first cycle.

[0077] The constant pressure and water supplement device is used for providing initial water for the third cycle and the fourth cycle pipeline, and ensuring that the system pressure is stable within a certain range to prevent water emptying or water vaporization. When the water loss caused by sewage and system dripping and other reasons causes the system pressure to decrease, the system is supplemented with water.

[0078] The air conditioning terminal equipment 23 is a capillary radiation terminal or an air handling unit. In some equipment rooms and management rooms, there is no indoor moisture source, and the main load is sensible heat load, so the capillary radiation terminal is designed in the application. Compared with the fan coil and the all-air system, the COP of the unit can be greatly improved. For the working room near the underground soil, there is a risk of wall water seepage, and there is a sensible heat load and a latent heat load, so an independent humidity control system such as an independent fresh air system should be added to the capillary radiation terminal. For the station hall and the platform layer public area with large passenger flow, the traditional all-air system is used.

[0079] The present application is based on the characteristics of the typical off-wall structure of the underground station, the contact of the station floor with the soil, and the available space inside the tunnel, and the capillary tube heat exchanger is laid in these structures to form the 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 realize the extraction of 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 tube heat exchanger is used to extract the heat in the soil and the tunnel to meet the heating demand of the equipment management room and other rooms and to produce domestic hot water. In summer, the capillary tube heat exchanger can also be used to extract the heat in the tunnel to produce domestic hot water for the overlying building. The technology effectively combines the capillary tube heat exchanger with the structure and space of the subway station itself, replaces the traditional soil source heat pump borehole heat exchanger, solves the problems of high drilling cost and occupation of underground space of the traditional borehole heat exchanger, effectively recovers the waste heat in the subway station and the tunnel, promotes the energy saving and emission reduction of the underground station air conditioning system, and reduces the energy consumption of the overlying building, the environmental pollution, and promotes the sustainable development.

[0080] Embodiment:

[0081] Some core components of the system of the present application will be further described in detail below in combination with a specific engineering example:

[0082] The core part of the underground station energy wall composite heat pump air conditioning system is the soil area capillary tube heat exchanger and the tunnel area capillary tube heat exchanger.

[0083] 1. Soil area capillary tube heat exchanger:

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

[0085] (1) Capillary tube energy wall 25:

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

[0087] Specifically:

[0088] 1) Underground station structure wall 2:

[0089] The underground station structure wall 2 is a commonly used reinforced concrete structure, and its thickness is generally 800-1000 mm, and the specific method is according to the relevant requirements of building.

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

[0091] The capillary grid pipe-embedded layer 3 is laid on the inner surface of the structural wall, i.e. the surface of the structural wall in the direction of the station side 8. The capillary grid pipe-embedded layer 3 is laid by using the wet installation method of the capillary grid, i.e. the capillary grid is directly laid on the inner surface of the structural wall and is fixed by using a pipe clamp, and finally is covered by plastering, and the thickness of the pipe-embedded layer is 30-50 mm.

[0092] By using the high thermal conductivity of graphite, the plastering layer cement mortar is adjusted to be a heat-conducting enhanced cement mortar, i.e. 30-50% of the mass fraction of graphite powder is used to replace the cement mortar mixed powder, the proportion of the cement mortar mixed powder is not changed, and the heat-conducting enhanced cement mortar is obtained by mixing uniformly before adding water. Since the present application is located on the surface of the structural wall and does not need to bear stress, the influence of the added graphite powder on the mechanical properties of the pipe-embedded layer can be ignored.

[0093] The capillary grid is made of polypropylene random (PP-R), and the capillary grid used in the present application is of the opposite water supply and return type. Compared with the same water supply and return type, the capillary grid has more branch pipes and a larger flow, and thus has a larger heat exchange capacity. The parameters of the capillary grid are as follows: the width of a single capillary grid is 1000 mm, the length is 600-12000 mm, the main pipe diameter is 20*2 mm, the branch pipe diameter is 3.5-4.5 mm, and the branch pipe wall thickness is 0.5-0.8 mm. The optimal pipe spacing should be 20 mm. If the branch pipe spacing is too large, the number of branch pipes will be reduced, and thus the total flow will also be reduced, which will result in a smaller heat exchange capacity. Although a smaller pipe spacing means a larger flow, a smaller pipe spacing will cause strong thermal interference between adjacent branch pipes, resulting in a decrease in the heat exchange temperature difference and a decrease in the heat exchange capacity. The optimal water flow rate in the branch pipe is 0.05-0.13 m / s. At a low flow rate (less than 0.05 m / s), the heat exchange of the circulating water in the branch pipe is sufficient, and the heat exchange capacity of the grid increases obviously with the increase of the flow rate. At an intermediate flow rate (0.05-0.13 m / s), the increase of the flow rate begins to affect the heat exchange effect of the circulating water. When the flow rate in the branch pipe increases, the growth trend of the heat exchange capacity gradually slows down. At a high flow rate (greater than 0.13 m / s), the heat exchange capacity of the grid almost does not increase with the increase of the flow rate in the branch pipe.

[0094] Each capillary grid is connected in parallel to the water supply and return main pipe. This connection mode ensures that each grid has a consistent water inlet temperature, which is helpful for uniform heat exchange. The water supply and return headers of each grid are connected by using a hot melting connection mode.

[0095] 3) Insulation layer 4:

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

[0097] 4) Air interlayer 6:

[0098] The air interlayer 6 (cavity) exists between the thermal insulation layer 4 and the off-wall wall 7, and is a space used by the underground station to isolate the indoor environment from the surrounding environment. In the application, the air interlayer 6 serves as a waterproof layer of the capillary tube energy wall 25 and a second layer of thermal insulation material, and its thickness is 100-250 mm. The role of the air interlayer 6 is to prevent groundwater from seeping into the interior of the station and to prevent heat in the buried pipe layer from being transmitted to the station side. When the capillary tube energy wall 25 is arranged in the public area of the station, the thickness of the cavity is 200-250 mm. When the capillary tube energy wall 25 is arranged in the equipment and management room of the station, the thickness of the cavity is 100-150 mm.

[0099] 5) Off-wall wall 7:

[0100] The off-wall wall 7 is also a moisture-proof wall, which is used to eliminate and reduce the influence of water leakage of the outer wall on the use and aesthetics of the interior space of the station. In the application, the off-wall wall 7 is made of fiber cement board, and the thickness is 50-100 mm. The inner surface of the cavity side of the off-wall wall 7 is coated with a low-emissivity coating or coated with a smooth low-emissivity aluminum-tin film, and the surface of the coating is treated to be smooth, so as to reduce the radiation heat exchange between the inner surface of the cavity side of the off-wall wall 7 and other surfaces and the convective heat exchange between the inner surface of the cavity side of the off-wall wall 7 and the air in the cavity, thereby reducing the heat transfer from the buried pipe layer to the station.

[0101] (2) Capillary tube heat exchanger of the station floor:

[0102] The soil temperature is stable throughout the year, and the station floor has a large contact area with the soil and is close to the underground water seepage area due to its deep burial depth. The application proposes to use the station floor as a heat exchanger carrier, and designs the capillary tube heat exchanger on the lower surface of the floor to exchange heat with the surrounding soil and underground water, as shown in FIG. 2. Figure 8 The presence of underground water not only enables better convective heat exchange, but also effectively prevents heat accumulation to extract cold energy in summer and heat energy in winter.

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

[0104] 2. Tunnel area capillary heat exchanger:

[0105] When the train runs in the station tunnel, the motor, braking system, and lighting device will generate a large amount of heat. Especially in summer or high temperature period, to maintain the comfortable temperature in the car, the air conditioning refrigeration is also turned on, which will also generate a large amount of condensation heat. Therefore, the temperature in the station tunnel is high all year round, with a minimum of about 18℃ in winter and a maximum of about 34℃ in summer. In order to prevent the temperature from being too high to cause adverse effects on the station, a track top air duct 11 is usually provided in the station tunnel to connect with the outside to remove these heat, so as to ensure that the temperature in the tunnel is not higher than 40℃. The present embodiment utilizes the available space inside the tunnel to set a capillary heat exchanger to recover the waste heat in the tunnel.

[0106] The tunnel area capillary heat exchanger includes a station tunnel wall capillary heat exchanger, a track top air duct capillary heat exchanger, an interval tunnel wall capillary heat exchanger, and a piston air shaft wall capillary heat exchanger.

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

[0108] The tunnel wall is flat, and grooves are opened on the surface, or spaces are reserved when the wall is poured, with a depth of 1 / 2 of the pipe diameter, so that the capillary tubes are 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 apply corrosion protection measures to the surface of the pipe, graphene composite material is selected for cold spraying on the surface of the pipe, which is mainly composed of graphene, graphite powder, and epoxy resin. The thermal conductivity of graphene is 5300W / (m·K), and according to the different content of graphene, the thermal conductivity of the composite material is about 5-40W / (m·K), which is 100 times higher than that of the capillary tube, and the material is corrosion resistant and not easy to fall off. After spraying, the color tone is consistent with the wall, ensuring the beauty of the wall.

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

[0111] (2) Track top air duct capillary heat exchanger:

[0112] Due to the small construction space in the tunnel, the rail top air duct cannot guarantee its quality in the secondary pouring process, so the prefabricated rail top air duct is widely used. The capillary tube is designed on the top surface of the bottom plate of the rail top air duct as a rail top air duct capillary heat exchanger. The prefabricated rail top air duct should reserve a pipe slot, then the capillary tube is fixed in the slot of the bottom plate, the pipe is exposed to the air, and the surface is sprayed with graphene composite material. This surface embedded pipe method will not affect the bearing structure of the rail top air duct.

[0113] (3) Interval tunnel wall capillary heat exchanger:

[0114] The lower part of the subway interval tunnel is the subway sleeper and the track bed, and the upper part is generally provided with fire water pipes, lighting and other equipment. Therefore, the capillary heat exchanger is arranged on the side wall space, the capillary tube is embedded on the surface of the wall by slotting, and the surface is sprayed with graphene composite material.

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

[0116] The piston air shaft is generally arranged at both ends of the tunnel and cooperates with the fan to serve the normal ventilation or emergency ventilation of the tunnel. With reference to the piston air shaft on one side of the interval tunnel, when the train arrives, the high-temperature air in the tunnel is extruded and discharged from the piston air shaft, at this time, the negative pressure is formed in the tunnel, and the low-temperature air outside is sucked into the other side of the air shaft to maintain the pressure balance of the tunnel, that is, the "piston effect".

[0117] Due to the smooth inner wall of the piston air shaft without additional equipment, the capillary tube is laid on the piston air wall. The capillary tube is embedded in the piston air shaft wall by slotting the piston air shaft wall, one side of the capillary tube is exposed to the air, and the surface is sprayed with graphene composite material.

[0118] According to the heating, air conditioning and domestic hot water demand of the station building and the overlying building, the system can extract the cold energy from the soil for indoor cooling, extract the heat from the soil for indoor heating or prepare domestic hot water, and additionally, the residual heat in the tunnel can be recovered for indoor heating or preparation of domestic hot water. According to the temperature characteristics of the air and soil medium around the heat exchanger, the capillary heat exchanger can be divided into two parts, one part is a tunnel area heat exchanger that can only extract the residual heat in the tunnel, and the other part is a soil area heat exchanger that can extract both the heat and cold energy in the soil according to the user's demand. Therefore, based on the seasonal user demand, the system operation mode can be divided into the following three types:

[0119] 1) Transition season

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

[0121] 2) Summer

[0122] The temperature in the tunnel in summer is the highest in a year, which can reach 34°C, while the temperature in the soil area is lower than the outside temperature, which is only about 16°C. Due to the diversity of heat exchangers in the energy underground station, the system can extract soil cold energy for station cooling and extract tunnel residual heat for hot water preparation for regional users. When the system is running, all valves are opened, and the tunnel area heat exchanger and the soil area heat exchanger (instead of the cooling tower) are opened at the same time, as shown in Figure 11 The low-temperature hot water of 15-25°C enters the tunnel area capillary heat exchanger (instead of the boiler) to extract residual heat in the tunnel, and the temperature rises. The heat in the evaporator of the heat pump unit is extracted, and then the refrigerant in the condenser releases heat to the hot water pipeline on the user side. For the soil area, the cooling water at 35°C enters the soil area capillary heat exchanger (instead of the cooling tower) to exchange heat with the surrounding low-temperature soil, and then enters the condenser of the heat pump unit to release cold energy to the refrigerant. Then, the evaporator releases cold energy to the chilled water pipeline, and finally transmits to the radiation terminal and air handling unit, respectively, to supply cooling to the equipment room and the public area of the station.

[0123] 3) Winter

[0124] In winter, there is less residual heat in the tunnel, which is difficult to meet the demand for domestic hot water and user-side radiant heating, and excessive extraction of residual heat in the tunnel may adversely affect the operation of the station, such as the risk of freezing and cracking of the water supply pipe due to the low temperature of the air in the tunnel. The soil area heat exchanger can also extract heat from the soil, and the heat balance 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, as shown in Figure 12 corresponding to the station tunnel wall capillary heat exchanger, the inter-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 inter-tunnel wall capillary heat exchanger stop running.

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

[0126] (1) The capillary heat exchanger is arranged on the inner surface of the station structure wall and the station floor, so that the underground renewable energy is extracted for cooling, and the traditional cooling tower can be reduced or replaced. The problems of large occupation of the cooling tower, difficult coordination arrangement, influence on landscape and noise disturbance of the public are solved, the occupation area of the cooling tower is saved, the initial investment of civil engineering is saved, and the environment is friendly.

[0127] (2) The capillary heat exchanger arranged in the tunnel and the air duct effectively recovers the waste heat in the tunnel, reduces the temperature in the tunnel, and reduces the high temperature risk when the train runs. Through the recovery of waste heat, energy saving and emission reduction of the underground station are promoted.

[0128] (3) The capillary heat exchanger is combined with the supporting structure of the underground station, which can effectively reduce the occupation space of the underground heat exchanger and maximize the use of building space.

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

[0130] (5) The capillary heat exchanger in the application is independent of the internal structure of the wall, and does not affect the mechanical properties of the envelope structure. Moreover, the construction is simple, and compared with the traditional energy underground structure, the construction difficulty is extremely low.

[0131] (6) The capillary energy wall provided by the application has good heat insulation measures, which ensures one-way heat exchange of the capillary energy wall to the soil side, so that the heat exchange process of the system does not affect the thermal environment in the station.

[0132] (7) The surface type capillary heat exchanger is used instead of the traditional large-diameter buried pipe heat exchanger, which saves the arrangement space, realizes more uniform heat exchange area, saves the cost of the heat plate, and has smaller noise.

[0133] (8) The combined heat pump of the soil source heat pump and the tunnel air source heat pump greatly improves the energy utilization efficiency, is reasonable in operation, and saves the air conditioning energy consumption.

[0134] The above application of specific examples is used to illustrate the application, which is only used to help understand the application, and does not limit the application. For the skilled in the art to which the application belongs, according to the idea of the application, a number of simple deductions, deformations or substitutions can be made.

Claims

1. A composite heat pump air conditioning system for an underground station's energy wall, characterized in that: The system includes a soil zone capillary heat exchanger, a tunnel zone capillary heat exchanger, a station machine room heat pump unit (22), air conditioning terminal equipment (23), and a domestic hot water tank (24). The soil capillary heat exchanger includes a capillary energy wall (25) and a station floor capillary heat exchanger. The capillary energy wall (25) is located on the soil side (1) of the station hall level (20), and the station floor capillary heat exchanger is located inside the station floor. The capillary heat exchangers in the tunnel area include capillary heat exchangers on the station tunnel walls, capillary heat exchangers on the track top ventilation ducts, capillary heat exchangers on the tunnel walls in the intervals, and capillary heat exchangers on the walls of the piston ventilation shafts. The soil capillary heat exchanger and the station machine room heat pump unit (22) are connected by a pipeline to form a circulation; The capillary heat exchanger in the tunnel area and the heat pump unit (22) in the station machine room are connected by a pipeline to form a circulation; The air conditioning terminal equipment (23) and the domestic hot water tank (24) are respectively connected to the heat pump unit (22) in the station machine room through pipelines to form a circulation.

2. The underground station energy wall composite heat pump air conditioning system according to claim 1, characterized in that: The capillary energy wall (25) includes an underground station structure wall (2), a capillary grid buried pipe layer (3), an insulation layer (4) and a separation wall (7), arranged sequentially from the soil side (1) to the station side (8), and there is an air gap (6) between the insulation layer (4) and the separation wall (7). An aluminum-tin film layer (5) is provided on the side of the insulation layer (4) near the air interlayer (6), and an aluminum-tin film layer (5) is provided on the side of the wall (7) near the air interlayer (6). The capillary grid buried pipe layer (3) is provided with a capillary grid (10).

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

4. The underground station energy wall composite heat pump air conditioning system according to claim 3, characterized in that: The capillary heat exchanger on the station tunnel wall, the capillary heat exchanger on the rail top ventilation duct, the capillary heat exchanger on the section tunnel wall, and the capillary heat exchanger on the piston ventilation shaft wall are connected in parallel with each other, and valves are respectively installed. They form a first circulation with the heat pump unit (22) in the station machine room through pipelines. The capillary energy wall (25) and the capillary heat exchanger of the station floor are connected in parallel, and valves are respectively installed. They form a second circulation with the heat pump unit (22) of the station machine room through pipelines. The air conditioning terminal equipment (23) forms a third circulation with the heat pump unit (22) in the station machine room through a valve and a pipeline; The domestic hot water tank (24) forms a fourth circulation with the heat pump unit (22) in the station machine room through a valve and a pipeline.

5. The underground station energy wall composite heat pump air conditioning system according to claim 4, characterized in that: The system also includes a pressure regulating and water replenishment device, which is connected to the third and fourth circulation systems.

6. The operation method of the underground station energy wall composite heat pump air conditioning system as described in claim 5, characterized in that: The method includes: When there is no demand for cooling or heating during the transition season, the valves of the first and fourth cycles are opened to extract the waste heat in the tunnel using the capillary heat exchangers on the tunnel wall, the capillary heat exchangers on the rail top duct, the capillary heat exchangers on the tunnel wall, and the capillary heat exchangers on the piston shaft wall. The waste heat is then exchanged through the heat pump unit (22) in the station machine room to produce domestic hot water.

7. The operation method of the underground station energy wall composite heat pump air conditioning system as described in claim 5, characterized in that: The method includes: In summer, open the valves for the first cycle, the second cycle, the third cycle, and the fourth cycle. The first cycle of circulating water extracts waste heat from the tunnel, and the temperature rises. The resulting heat is exchanged by the heat pump unit in the station machine room for the fourth cycle to produce domestic hot water. The circulating water in the second cycle exchanges heat with the soil, and the temperature decreases. The resulting cooling is then exchanged by the heat pump unit (22) in the station machine room to provide cooling for the third cycle.

8. The operation method of the underground station energy wall composite heat pump air conditioning system as described in claim 5, characterized in that: The method includes: In winter, open the valves of the capillary heat exchangers on the tunnel walls of the station, the capillary heat exchangers on the tunnel walls of the section, and the capillary heat exchangers of the piston ventilation shaft in the first cycle, as well as the valves in the second, third, and fourth cycles. The circulating water in the first cycle extracts the waste heat in the tunnel, and the temperature rises. The heat brought by this rise is exchanged by the heat pump unit (22) in the station machine room to provide heat for the third and fourth cycles. In the second cycle, the circulating water exchanges heat with the soil, and the temperature rises. The heat generated is then exchanged by the heat pump unit (22) in the station machine room to provide heat for the third and fourth cycles.

9. The operation method of the underground station energy wall composite heat pump air conditioning system according to claim 8, characterized in that: When the air temperature inside the tunnel is less than or equal to 5℃, the valves of the capillary heat exchangers on the tunnel wall of the station and the section tunnel wall in the first cycle are further closed.

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

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