A system and control method for heat storage and extraction in tunnel surrounding rock.

Abstract

This invention discloses a system and control method for heat storage and extraction in tunnel surrounding rock, comprising multiple interconnected heat exchangers. Each heat exchanger includes a heat exchanger tube bundle mounted inside a shell via a fixed support. The shell is also uniformly filled with a heat storage material, which encapsulates the heat exchanger tube bundle within the shell and maintains heat conduction between the shell and the heat exchanger tube bundle. The inlet and outlet of the heat exchanger tube bundle extend to the outer wall of the shell, with the inlet connected to a supply branch pipe and a supply main pipe, and the outlet connected to a return branch pipe and a return main pipe. By placing the heat exchangers within the concrete space of the subway invert arch, this invention greatly simplifies the construction process, avoids interference with the subway tunnel construction process, and, since the invert arch space contains only concrete, is not affected by other components.

Description

Technical Field

[0001] This invention relates to the field of building energy conservation and environmental protection, and in particular to a heat exchange system and system installed in the invert arch of a subway tunnel. Background Technology

[0002] Renewable energy sources such as solar and geothermal energy are widely used in building heating and cooling industries. However, their instability and low energy density can easily lead to an imbalance between energy supply and demand on the source and load sides, resulting in energy waste. The emergence of thermal storage materials has provided convenience for heat storage and reuse. Subway tunnels have enormous thermal storage potential, with a large amount of heat that can be stored within the surrounding rock. Therefore, front-end heat exchanger modules can be used to transfer solar energy and waste heat from above-ground buildings to the surrounding rock for storage and use in building heating. The inventors discovered that current front-end heat exchanger modules used in tunnels can only perform either heat storage or heat extraction functions independently, and cannot perform both simultaneously. This means that when a heat pump extracts heat from the surrounding rock for building heating, excess heat collected in the above-ground space cannot be stored in the surrounding rock in a timely manner. Summary of the Invention

[0003] In order to solve the technical problems existing in the prior art, the present invention provides a system and control method for heat storage and heat extraction in tunnel surrounding rock, which can effectively store heat energy in subway tunnels and realize the synchronous heat storage and heat extraction functions of the front-end heat exchanger module.

[0004] To achieve the above objectives, the present invention provides the following technical solution: a system for heat storage and extraction in tunnel surrounding rock, comprising a plurality of front-end heat exchanger modules, each front-end heat exchanger module comprising two heat extraction pipes and one heat storage pipe, wherein the two heat extraction pipes are located on both sides of the heat storage pipe and connected in series; a first connecting pipe connecting the two heat extraction pipes is connected to the heat storage pipe.

[0005] Several front-end heat exchanger modules are arranged along the tunnel axis and connected in parallel to the main pipe. The outlet section of one heat exchanger pipe is connected to the heat return water main pipe, and then connected to the circulating water pump and the ground source heat pump unit in sequence. Then, it is connected to the inlet section of another heat exchanger pipe through the heat supply water main pipe, forming a closed heat exchange loop.

[0006] The inlet section of the heat storage pipe is connected to the heat storage water supply main pipe, and then sequentially connected to the circulating water pump, electric valve, plate heat exchanger, and heat storage tank. Finally, it is connected to the return section of the heat storage pipe through the heat storage return water main pipe, forming a closed heat storage loop.

[0007] Preferably, the two heat exchange tubes are a first heat exchange tube and a second heat exchange tube, respectively;

[0008] The inlet section of the first heat extraction pipe is connected to the inlet section of the heat storage pipe through a second connecting pipe, and the opening and closing of the second connecting pipe is controlled by a first valve.

[0009] The return section of the heat storage pipe is connected to the first connecting pipe through a third connecting pipe, and the opening and closing of the third connecting pipe is controlled by a second valve.

[0010] The return water section of the second heat extraction pipe is connected to the return water section of the heat storage pipe through a fourth connecting pipe, and the opening and closing of the fourth connecting pipe is controlled by a third valve.

[0011] Preferred options also include:

[0012] Temperature sensors are used to detect the temperature of the liquid in the heat extraction loop and the heat storage loop.

[0013] Preferably, a fourth valve is provided at the inlet and outlet of the first heat extraction pipe, the second heat extraction pipe, and the heat storage pipe.

[0014] The present invention also proposes a system control method for heat storage and heat extraction in tunnel surrounding rock. The system mentioned above has three operating modes: the first operating mode is to perform only the heat extraction mode, the second operating mode is to perform only the heat storage mode, and the third operating mode is to perform both the heat storage mode and the heat extraction mode simultaneously.

[0015] The control method is as follows:

[0016] During the heating season, the system operates in only the first mode, or simultaneously in both the first and third modes. Specifically: the ground source heat pump unit and circulating water pump are activated to enable the heat extraction loop to operate in heat extraction mode, transferring heat to end users for heating. If there is residual heat from above-ground facilities (such as solar collectors), the plate heat exchanger and circulating water pump can also be activated to enable the heat storage loop to operate in heat storage mode, thereby achieving simultaneous heat storage and extraction from the front-end heat exchanger modules. If there is no residual heat generated by above-ground facilities, the heat storage loop is shut down, and the front-end heat exchanger modules operate only in heat extraction mode.

[0017] During the cooling season, the system operates in only the second mode, or simultaneously in both the first and third modes. Specifically: when end users require heat transfer from within the building, the ground source heat pump unit and circulating water pump are activated to put the heat extraction loop into heat storage mode. If there is residual heat generated by the above-ground facilities, the heat storage loop also operates into heat storage mode when the plate heat exchanger and circulating water pump are activated. At this time, both the heat storage loop and the heat extraction loop operate into heat storage mode simultaneously.

[0018] During the transition season, the system operates in a second mode. Specifically, when there is no cooling or heating demand at the user end, the heat extraction loop is shut down. If the above-ground facilities generate heat from waste heat, the heat storage loop operates in heat storage mode when the plate heat exchanger and circulating water pump are turned on.

[0019] Preferably, the first operating mode specifically includes: opening the first valve, the second valve, and the fourth valve at the inlet and outlet of the two heat extraction pipes; closing the third valve and the fourth valve at the inlet and outlet of the heat storage pipe; connecting the heat storage pipe and the heat extraction pipe through connecting pipes; and starting the ground source heat pump unit to extract heat from the surrounding rock.

[0020] Preferably, the second operating mode specifically includes: opening the first valve, the second valve, and the fourth valve at the inlet and outlet of the heat storage pipe; closing the third valve and the fourth valve at the inlet and outlet of the two heat extraction pipes; the heat storage pipe and the first heat extraction pipe are connected through the first connecting pipe; all three sets of pipes are in heat storage mode; and heat is stored in the surrounding rock through the heat storage loop connected to the plate heat exchanger.

[0021] Preferably, the third operating mode specifically includes: opening the fourth valve at the inlet and outlet of the heat storage pipe and the two heat extraction pipes, closing the second valve, and operating the two heat extraction pipes and the heat storage pipe independently. The ground source heat pump unit extracts heat from the surrounding rock and the heat storage pipe through the heat extraction loop for building heating, and the plate heat exchanger stores heat in the surrounding rock through the heat storage loop.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] This invention utilizes valve switching to control the operation of the heat extraction and heat storage tubes in the front-end heat exchanger module. The front-end heat exchanger module can operate in heat storage or heat extraction mode independently, or simultaneously in both modes. This allows excess heat from above-ground facilities to be stored and utilized, thereby improving the supply-demand imbalance between the source and load sides, alleviating the thermal imbalance of the surrounding rock, and increasing the overall energy utilization rate. Attached Figure Description

[0024] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used to explain the invention in conjunction with the embodiments of the invention and do not constitute a limitation thereof. In the drawings:

[0025] Figure 1 This is a schematic diagram of the system structure of the present invention;

[0026] Figure 2 This is a schematic diagram of the front-end heat exchanger module structure of the present invention;

[0027] Figure 3 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module under operating conditions of the present invention.

[0028] Figure 4 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module under operating condition two of the present invention;

[0029] Figure 5 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module under operating condition three of the present invention.

[0030] Figure 6 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module under operating condition four of the present invention.

[0031] Figure 7 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module under operating condition five of the present invention;

[0032] Figure 8 This is a schematic diagram of the fluid flow direction within the front-end heat exchanger module of the present invention under operating condition six.

[0033] In the diagram: 1. Front-end heat exchanger module; 2. Heat extraction supply water main; 3. Heat storage supply water main; 4. Heat storage return water main; 5. Heat extraction return water main; 6. Circulating water pump; 7. Temperature sensor; 8. Ground source heat pump unit; 9. Electric valve; 10. Plate heat exchanger; 11. Hot water storage tank; 12. First heat extraction pipe; 13. Second heat extraction pipe; 14. Heat storage pipe; 15. First connecting pipe; 16. Second connecting pipe; 17. First valve; 18. Third connecting pipe; 19. Second valve; 20. Fourth connecting pipe; 21. Third valve; 22. Fourth valve. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. The components of the embodiments of the present invention described and shown in the accompanying drawings can generally be arranged and designed in various different configurations. Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0035] As introduced in the background section, the imbalance between supply and demand on the source and load sides causes a huge waste of energy. In order to solve the above problems, a system for heat storage and extraction in tunnel surrounding rock is proposed.

[0036] To enable those skilled in the art to more clearly understand the technical solution of the present invention, the following will be combined with... Figure 1-8 The technical solution of the present invention will be described in detail with specific embodiments.

[0037] A system for storing and extracting heat from surrounding rock in a tunnel includes several front-end heat exchanger modules 1. Each front-end heat exchanger module 1 includes two heat extraction pipes and one heat storage pipe 14. The two heat extraction pipes are located on both sides of the heat storage pipe 14 and connected in series. A first connecting pipe 15 connecting the two heat extraction pipes is connected to the heat storage pipe 14.

[0038] Several front-end heat exchanger modules 1 are arranged along the tunnel axis and connected in parallel to the main pipe. The outlet section of one of the heat exchanger pipes is connected to the heat return water main pipe 5, and then connected in sequence to the circulating water pump 6 and the ground source heat pump unit 8. Finally, it is connected to the inlet section of another heat exchanger pipe through the heat supply water main pipe 2, forming a closed heat exchange loop.

[0039] The inlet section of the heat storage pipe 14 is connected to the heat storage water supply main pipe 3, and is sequentially connected to the circulating water pump 6, electric valve 9, plate heat exchanger 10, and heat storage tank 11. Finally, it is connected to the return section of the heat storage pipe through the heat storage return water main pipe 4, forming a closed heat storage loop.

[0040] like Figure 2 As shown, the two heat exchange pipes are the first heat exchange pipe 12 and the second heat exchange pipe 13. The inlet section of the first heat exchange pipe 12 is connected to the inlet section of the heat storage pipe 14 via a second connecting pipe 16, and the opening and closing of the second connecting pipe 16 is controlled by a first valve 17. The return section of the heat storage pipe 14 is connected to the first connecting pipe 15 via a third connecting pipe 18, and the opening and closing of the third connecting pipe 18 is controlled by a second valve 19. The return section of the second heat exchange pipe 13 is connected to the return section of the heat storage pipe 14 via a fourth connecting pipe 20, and the opening and closing of the fourth connecting pipe 20 is controlled by a third valve 21. These three connecting pipes and three valves establish connections between the three sets of pipes, allowing for different operating conditions.

[0041] The circulating water pumps 6 are respectively arranged on the return water pipes of the heat extraction loop and the heat storage loop to provide power for the flow of the circulating medium; the temperature sensors 7 are arranged on the inlet and outlet pipes of each piece of equipment to monitor the temperature of the fluid in each pipe, thereby transmitting the information to the control center to control the start-up, shutdown and operation mode of other equipment.

[0042] During the heating season, the ground source heat pump unit 8 is turned on, extracting heat from the surrounding rock through the heat extraction loop and supplying heat to end users. When the temperature sensor 7 in the heat extraction return water main 5 detects that the return water temperature is below 10℃, the system is shut down until the detected return water temperature is above 13℃. If the temperature of the hot water storage tank 11 is above 45℃ at this time, the plate heat exchanger 10 is turned on to store heat into the surrounding rock through the heat storage loop, and the front-end heat exchanger module 1 performs both heat storage and heat extraction operations simultaneously. If the temperature of the hot water storage tank 11 is below 35℃, the hot water storage tank 11 is turned off until the water temperature is above 45℃ and then turned on, at which time the front-end heat exchanger module 1 only performs heat extraction operations.

[0043] During the transitional season, plate heat exchanger 10 is turned on to transfer waste heat from the above-ground equipment to the surrounding rock for storage through the heat storage loop. When the temperature sensor 7 detects that the temperature of the hot water storage tank 11 is below 35°C, the heat storage loop is turned off until the water temperature is above 45°C. At this time, the end users do not need cooling or heating, so the ground source heat pump unit 8 is turned off, and the front-end heat exchanger module 1 only operates in heat storage mode.

[0044] During the cooling season, the ground source heat pump unit 8 is turned on, transferring heat from the building to the surrounding rock for storage through the heat extraction loop to achieve the purpose of cooling. When the temperature sensor 7 on the heat extraction return water main 5 detects a return water temperature higher than 38℃, the system is shut down until the measured return water temperature drops below 35℃, at which point the system is turned back on. Simultaneously, the plate heat exchanger 10 is turned on, storing the waste heat from the above-ground equipment in the surrounding rock through the heat storage loop. When the temperature of the hot water storage tank 11 drops below 35℃, the hot water storage tank 11 is shut down until the water temperature rises above 45℃, at which point it is turned back on. At this time, both the heat extraction loop and the heat storage loop are operating in heat storage mode.

[0045] The control method for front-end heat exchanger module 1 is as follows:

[0046] Operating conditions as before Figure 3 As shown, the heat storage and heat extraction modes in the front-end heat exchanger module 1 are performed simultaneously. The fourth valve 22 at the inlet and outlet of the heat storage pipe 14 and the two heat extraction pipes is opened, and the first valve 17, the second valve 19 and the third valve 21 connecting the heat storage pipe 14 and the two heat extraction pipes are closed, so that the two heat extraction pipes and the heat storage pipe 14 are divided into two systems. The ground source heat pump unit 8 extracts heat from the surrounding rock and the heat storage pipe 14 through the two heat extraction pipes for building heating, and the hot water storage tank 11 stores heat into the surrounding rock through the heat storage pipe 14.

[0047] Operating Condition Two Figure 4 As shown, the front-end heat exchanger module 1 only operates in heat extraction mode. The first valve 17 and the second valve 19 are opened, while the third valve 21 and the fourth valve 22 at the inlet and outlet of the two heat extraction pipes are closed. The fourth valve 22 at the inlet and outlet of the heat storage pipe 14 is also closed. At this time, some fluid in the first heat extraction pipe 12 enters the heat storage pipe 14 through the second connecting pipe 16. Then, the fluid in the heat storage pipe 14 mixes with the fluid in the first heat extraction pipe 12 through the first connecting pipe 15 and enters the second heat extraction pipe 13. Finally, all fluids flow into the ground source heat pump unit 8, thereby transferring heat from the surrounding rock to the user terminal.

[0048] The front-end heat exchanger module 1 only performs heat storage operation, which can be mainly divided into two cases:

[0049] In the first scenario, the ground source heat pump unit 8 stops operating, the heat extraction loop is closed, and heat is stored only through the hot water storage tank 11 and the heat storage loop. (Operating condition three...) Figure 5As shown, the first valve 17 and the second valve 19 at the water inlet section are opened, and the fourth valve 22 at the inlet and outlet of the two heat exchanger tubes is closed. At this time, part of the fluid in the heat storage tube 14 enters the first heat exchanger tube 12 through the second connecting pipe 16. Then, the remaining fluid in the heat storage tube 14 is mixed with the fluid in the first heat exchanger tube 12 through the first connecting pipe 15 and enters the second heat exchanger tube 13. Then, the fluid flows into the plate heat exchanger 10, thereby storing heat in the surrounding rock.

[0050] In the second scenario, when both the heat extraction loop and the heat storage loop are in heat storage mode simultaneously, the fourth valve 22 at the inlet and outlet of the heat storage pipe 14 and the two heat extraction pipes is opened.

[0051] (1) When the inlet temperature difference between the heat storage tube 14 and the first heat extraction tube 12 is less than 2℃, the operating condition is as follows: Figure 6 As shown, the front-end heat exchanger module 1 opens the second valve 19 and the third valve 21, and closes the first valve 17. At this time, all three sets of pipes are in heat storage mode. The first heat extraction pipe 12 and the heat storage pipe 14 initially operate independently. Through the first connecting pipe 15, the circulating fluid in both sets of pipes enters the second heat extraction pipe 13 for heat storage, storing heat in the surrounding rock. Finally, the fluid is divided through the fourth connecting pipe 20, with one part flowing into the ground source heat pump unit 8 and the other part flowing into the plate heat exchanger 10.

[0052] (2) When the inlet temperature of the heat storage tube 14 is more than 10°C higher than the inlet temperature of the first heat extraction tube 12, operating condition five is as follows. Figure 7 As shown, the front-end heat exchanger module 1 opens the first valve 17, the second valve 19, and the third valve 21. Initially, part of the fluid in the heat storage tube 14 enters the internal fluid of the first heat extraction tube 12 through the second connecting pipe 16 to mix and increase its inlet temperature. Then, through the first connecting pipe 15, the circulating fluid in both sets of pipes enters the second heat extraction tube 13 for heat storage, storing heat in the surrounding rock. Finally, the fluid is split through the fourth connecting pipe 20, with part flowing into the ground source heat pump unit 8 and part flowing into the plate heat exchanger 10.

[0053] (3) When the inlet temperature of the first heat extraction tube 12 is more than 10°C higher than the outlet temperature of the heat storage tube 14, operating condition six is ​​as follows. Figure 8 As shown, the front-end heat exchanger module 1 opens the first valve 17 and the third valve 21, and closes the second valve 19. Initially, part of the fluid in the first heat extraction tube 12 enters the heat storage tube 14 through the second connecting pipe 16 and mixes with the fluid inside. Then, part of the fluid in the heat storage tube 14 returns to the second heat extraction tube 13 through the third connecting pipe 18 and flows into the ground source heat pump unit 8. The remaining fluid in the heat storage tube 14 enters the plate heat exchanger 10.

[0054] The applicant declares that the present invention is illustrated by the above examples, but the present invention is not limited to the above detailed methods, that is, it does not mean that the present invention must rely on the above detailed methods to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent transformations of the raw materials, addition of auxiliary components, selection of specific conditions and methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A system for heat storage and extraction in tunnel surrounding rock, characterized in that, It includes several front-end heat exchanger modules, each of which includes two heat-extracting tubes and one heat-storing tube. The two heat-extracting tubes are located on both sides of the heat-storing tube and connected in series. The first connecting pipe connecting the two heat-extracting tubes is connected to the heat-storing tube. Several front-end heat exchanger modules are arranged along the tunnel axis and connected in parallel to the main pipe. The outlet section of one heat exchanger pipe is connected to the heat return water main pipe and then connected to the circulating water pump and the ground source heat pump unit in sequence. Then, it is connected to the inlet section of another heat exchanger pipe through the heat supply water main pipe to form a closed heat exchange loop. The inlet section of the heat storage pipe is connected to the heat storage water supply main pipe, and then connected in sequence to the circulating water pump, electric valve, plate heat exchanger, and heat storage tank. Finally, it is connected to the return section of the heat storage pipe through the heat storage return water main pipe, forming a closed heat storage loop. The two heat-extracting pipes are designated as the first heat-extracting pipe and the second heat-extracting pipe; a fourth valve is provided at the inlet and outlet of the first heat-extracting pipe, the second heat-extracting pipe, and the heat storage pipe; The inlet section of the first heat extraction pipe is connected to the inlet section of the heat storage pipe through a second connecting pipe, and the opening and closing of the second connecting pipe is controlled by a first valve. The return section of the heat storage pipe is connected to the first connecting pipe through a third connecting pipe, and the opening and closing of the third connecting pipe is controlled by a second valve. The return water section of the second heat extraction pipe is connected to the return water section of the heat storage pipe through a fourth connecting pipe, and the opening and closing of the fourth connecting pipe is controlled by a third valve.

2. The system for heat storage and extraction in tunnel surrounding rock according to claim 1, characterized in that, It also includes: Temperature sensors are used to detect the temperature of the liquid in the heat extraction loop and the heat storage loop.

3. A system control method for heat storage and extraction in tunnel surrounding rock, wherein the system is the system for heat storage and extraction in tunnel surrounding rock as described in claim 2, characterized in that, The system has three operating modes: the first mode is to perform heat extraction only, the second mode is to perform heat storage only, and the third mode is to perform heat storage and heat extraction simultaneously. The control method is as follows: During the heating season, the system may only execute the first operating mode, or execute the first and third operating modes simultaneously. During the cooling season, the system only executes the second operating mode, or the first and third operating modes are executed simultaneously; During the transition season, the system executes the second operating mode.

4. A control method for a system for heat storage and extraction in tunnel surrounding rock according to claim 3, characterized in that, The first operating mode specifically includes: opening the first valve, the second valve, and the fourth valve at the inlet and outlet of the two heat extraction pipes; closing the third valve and the fourth valve at the inlet and outlet of the heat storage pipe; connecting the heat storage pipe and the heat extraction pipe through the first connecting pipe; and starting the ground source heat pump unit to extract heat from the surrounding rock.

5. A control method for a system for heat storage and extraction in tunnel surrounding rock according to claim 4, characterized in that, The second operating mode specifically includes: opening the first valve, the second valve, and the fourth valve at the inlet and outlet of the heat storage pipe; closing the third valve and the fourth valve at the inlet and outlet of the two heat extraction pipes; the heat storage pipe and the first heat extraction pipe are connected through the first connecting pipe; all three sets of pipes are in heat storage mode; and heat is stored in the surrounding rock through the heat storage loop connected to the plate heat exchanger.

6. A control method for a system for heat storage and extraction in tunnel surrounding rock according to claim 5, characterized in that, The third operating mode specifically includes: opening the fourth valve at the inlet and outlet of the heat storage pipe and the two heat extraction pipes, closing the second valve, and operating the two heat extraction pipes and the heat storage pipe independently. The ground source heat pump unit extracts heat from the surrounding rock and the heat storage pipe through the heat extraction loop for building heating, and the plate heat exchanger stores heat in the surrounding rock through the heat storage loop.

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