Energy tunnel self-anti-freezing structure and method based on surrounding rock cross-seasonal heat storage technology

Abstract

The present invention discloses an energy tunnel self-anti-freezing structure and method based on the surrounding rock cross-seasonal heat storage technology. The structure includes heat pipes, heat exchange pipelines, a solar energy heat exchanger, a surrounding rock temperature monitoring system, and a heat storage automatic control system. The solar energy heat exchanger is installed outside the tunnel and is controlled by the heat storage automatic control system. The heat exchange pipelines are connected to the solar energy heat exchanger through a water distribution pipe and a water collecting pipe, and the heat exchange pipelines are buried between the primary lining and the waterproof board of the tunnel. One end of the heat pipe is buried in the primary lining of the tunnel, and the other end is buried in the surrounding rock. A temperature sensor is installed at one end of the heat pipe close to the surrounding rock, and all the temperature sensors form the surrounding rock temperature monitoring system. The present invention breaks through the limitation of the traditional energy tunnel anti-freezing technology that only extracts geothermal energy near the lining by arranging heat pipes in the surrounding rock to store heat energy in the surrounding rock at different depths, fully utilizes the energy storage space of the tunnel surrounding rock, and solves the tunnel freezing damage problem with low energy consumption.

Description

Technical Field

[0001] The present invention relates to the technical field of self - antifreeze for energy tunnels, and particularly relates to an energy tunnel self - antifreeze structure and method based on surrounding - rock cross - season heat storage technology. Background Technique

[0002] The energy tunnel technology is a new type of shallow geothermal energy development technology. The ground - source heat pump heat - exchange system is arranged inside the tunnel structure, and the shallow geothermal energy in the surrounding rock of the tunnel is extracted by using the heat - transfer circulating medium in the pipe for heating and cooling of the tunnel itself and the surrounding buildings. It has the advantages of low construction cost and space saving. In addition, for a tunnel with a certain length, the shallow geothermal energy in the middle of the tunnel can be collected by using the ground - source heat pump system. The main circuit is arranged at a position with a higher temperature, and the secondary circuit is arranged at a position prone to frost damage. The energy tunnel can solve the tunnel frost - damage problem with lower energy consumption.

[0003] However, it is found in engineering applications that the traditional energy - tunnel antifreeze technology is greatly affected by the external air temperature. In winter, due to the low surface temperature, the heat - transfer efficiency of the ground - source heat pump system decreases, thus affecting the tunnel antifreeze effect. In addition, in practical applications, the distribution of geothermal energy is often relatively scattered, and heat exchange needs to be carried out many times inside the tunnel to extract sufficient heat energy. Moreover, the thermal conductivity of the tunnel surrounding rock is poor, resulting in a reduction in the extraction efficiency of geothermal energy and affecting the tunnel antifreeze performance.

[0004] In addition, scholars from various countries have carried out many feasibility studies based on actual projects for problems such as the heat - exchange potential and economic benefits of the energy - tunnel heat - exchange system under different surrounding - rock conditions. The research shows that the heat exchange amount per unit area of the surrounding rock of the conventional energy tunnel is not high, with values ranging from 18 W / m 2 to 120 W / m 2 varying, which is about the heat exchange amount of the vertical borehole per unit length. The antifreeze efficiency is low, and the advantage of the large energy - storage space of the tunnel surrounding rock has not been exerted. There is an urgent need to develop new energy - tunnel self - antifreeze technologies (Frodl, 2011; Cousin, 2019; Insana, 2020; Barla, 2023). Summary of the Invention

[0005] The purpose of the present invention is to provide an energy - tunnel self - antifreeze structure and method based on solar heat exchangers to achieve cross - season heat storage of the surrounding rock in view of the problems raised in the background technique, realize the cross - season utilization of heat energy, and store the heat energy in the surrounding rock at different depths by arranging heat pipes in the surrounding rock, breaking through the limitation of the traditional energy - tunnel antifreeze technology that only extracts geothermal energy near the lining, making full use of the energy - storage space of the tunnel surrounding rock, and solving the tunnel frost - damage problem with low energy consumption.

[0006] To achieve the above purpose, the present invention provides the following technical solutions:

[0007] An energy tunnel self - anti - freezing structure based on surrounding rock cross - seasonal heat storage technology, including heat pipes, heat exchange pipelines, solar heat exchangers, surrounding rock temperature monitoring systems, and heat storage automatic control systems.

[0008] The solar heat exchanger is installed outside the tunnel and is controlled by the heat storage automatic control system.

[0009] The heat exchange pipeline is buried between the primary lining and the waterproof board of the tunnel along the length direction of the tunnel, and is connected to the solar heat exchanger through a water distribution pipe and a water collecting pipe.

[0010] One end of the heat pipe is buried into the primary lining of the tunnel, and the other end is buried into the surrounding rock. A temperature sensor is installed at the end of the heat pipe close to the surrounding rock. All temperature sensors form a surrounding rock temperature monitoring system.

[0011] In summer, when the external air temperature of the tunnel rises to a certain temperature, the heat storage automatic control system automatically turns on the solar heat exchanger outside the tunnel. The heat energy absorbed by the solar heat exchanger is then transmitted into the primary lining of the tunnel through the heat exchange pipeline between the primary lining and the waterproof board by the water distribution pipe and the water collecting pipe, and the heat energy is stored in the surrounding rock through the heat pipe. At the same time, the surrounding rock temperature monitoring system monitors the surrounding rock temperature in real time. When the surrounding rock reaches a certain temperature, the heat storage automatic control system automatically turns off the solar heat exchanger and stops heat storage.

[0012] In winter, the heat energy in the surrounding rock is slowly released to the primary lining of the tunnel by the heat pipe, increasing the temperature of the primary lining of the tunnel and achieving the effect of self - anti - freezing.

[0013] The type of the heat pipe is a gravity heat pipe, which is installed in the hollow anchor bolt in the surrounding rock or directly installed in the drill hole of the surrounding rock, and is arranged at the arch foot of the surrounding rock.

[0014] The heat pipe includes a heat storage heat pipe and a heat release heat pipe. Considering the working principle that the gravity heat pipe can transfer the heat of the evaporation section to the condensation section, the heat storage heat pipe and the heat release heat pipe are arranged alternately along the tunnel axis at a certain inclination angle when installed. The minimum interval is 1 m. The heat storage heat pipe has a negative inclination angle, and the heat release heat pipe has a positive inclination angle. The inclination angle range is ±15 - 45 degrees to ensure that the condensed working fluid in the heat pipe can flow back to the evaporation section by gravity for cyclic heat transfer.

[0015] The lengths of the heat pipes are different, including medium - temperature heat storage heat pipes and high - temperature heat storage heat pipes. The medium - temperature heat storage heat pipes are arranged in the medium - temperature heat storage area of the surrounding rock, and the working temperature of the medium - temperature heat storage heat pipes is above 20°C.

[0016] The high - temperature heat storage heat pipes are arranged in the high - temperature heat storage area of the surrounding rock, and the working temperature of the high - temperature heat storage heat pipes is above 30°C.

[0017] The heat storage medium-temperature zone is the surrounding rock at a distance of 0 - 5 m from the surface of the primary lining, and the heat storage high-temperature zone is the surrounding rock at a distance of 5 - 10 m from the surface of the primary lining.

[0018] After the heat pipes are arranged, a heat insulation layer is laid on the surface of the secondary lining of the tunnel to reduce the heat loss in the surrounding rock.

[0019] The present invention further discloses an energy tunnel self-freezing prevention method based on the surrounding rock cross-seasonal heat storage technology. Based on the energy tunnel self-freezing prevention structure based on the surrounding rock cross-seasonal heat storage technology, the process of heat storage in the surrounding rock by the heat storage automatic control system in summer is divided into two steps, that is, first heat storage in the heat storage medium-temperature zone and then heat storage in the heat storage high-temperature zone; the difference in heat storage temperature is achieved by the heat storage automatic control system adjusting the power of the solar heat exchanger; the specific process is as follows:

[0020] First, heat storage is carried out in the heat storage medium-temperature zone. When the surrounding rock temperature monitoring system measures that the surrounding rock temperature in the heat storage medium-temperature zone reaches 18 - 20 °C, the heat storage automatic control system increases the power of the solar heat exchanger, so as to carry out heat storage in the heat storage high-temperature zone;

[0021] When the surrounding rock temperature monitoring system measures that the surrounding rock temperature in the heat storage high-temperature zone reaches 28 - 30 °C, the heat storage automatic control system turns off the solar heat exchanger and stops heat storage.

[0022] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0023] The present invention combines the solar heat exchanger and the energy tunnel technology, and introduces gravity heat pipes to realize the cross-seasonal heat storage of the surrounding rock, solves the problems of the traditional energy tunnel freezing prevention method, such as the poor thermal conductivity of the tunnel surrounding rock, the relatively dispersed geothermal energy distribution, and the large influence of the external air temperature on the extraction efficiency, and the general freezing prevention performance, improves the energy utilization efficiency, solves the energy tunnel freezing damage problem, and prolongs the service life of the tunnel, which has important significance. Description of the Drawings

[0024] Figure 1 It is a cross-sectional view of the energy tunnel self-freezing prevention structure for realizing the cross-seasonal heat storage of the surrounding rock based on the solar heat exchanger of the present invention;

[0025] Figure 2 It is a sectional view of the energy tunnel adopting this structure;

[0026] In the figure: heat pipe 1, heat exchange pipeline 2, tunnel primary lining 3, waterproof board 4, tunnel secondary lining 5, heat insulation layer 6, solar heat exchanger 7, water distribution pipe 8, water collection pipe 9, surrounding rock 10, temperature sensor 11, heat storage automatic control system 12. Embodiment

[0027] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not used to limit the present invention. Embodiment

[0028] An anti-freezing structure for an energy tunnel that realizes cross-seasonal heat storage in surrounding rock based on a solar heat exchanger, as Figure 1 shown, includes a heat pipe 1, a heat exchange pipeline 2, a solar heat exchanger 7, a surrounding rock temperature monitoring system, and a heat storage automatic control system 12. The solar heat exchanger 7 is installed outside the tunnel and is controlled by the heat storage automatic control system 12. The heat exchange pipeline 2 is connected to the solar heat exchanger 7 through a water distribution pipe 8 and a water collecting pipe 9. The heat exchange pipeline 2 is buried between the primary lining 3 and the waterproof board 4 of the tunnel. One end of the heat pipe 1 is buried into the primary lining 3 of the tunnel, and the other end of the heat pipe 1 is buried into the surrounding rock 10. A temperature sensor 11 is installed at one end of the heat pipe 1 close to the surrounding rock 10. All the temperature sensors 11 form a surrounding rock temperature monitoring system;

[0029] First, in summer, when the external temperature of the tunnel rises to a certain temperature, the heat storage automatic control system 12 automatically turns on the solar heat exchanger 7 outside the tunnel. The heat energy absorbed by the solar heat exchanger 7 is then transmitted into the primary lining 3 of the tunnel through the heat exchange pipeline 2 between the primary lining 3 and the waterproof board 4 via the water distribution pipe 8 and the water collecting pipe 9, and the heat energy is stored into the surrounding rock 10 through the heat pipe 1. At the same time, the surrounding rock temperature monitoring system monitors the temperature of the surrounding rock in real time. When the surrounding rock 10 reaches 30 °C, the heat storage automatic control system 12 automatically turns off the solar heat exchanger 7 and stops heat storage. Second, in winter, the heat energy in the surrounding rock 10 is slowly released to the primary lining 3 of the tunnel by the heat pipe 1, so that the temperature of the primary lining 3 rises, achieving the effect of self-anti-freezing.

[0030] The type of the heat pipe 1 is a gravity heat pipe, which can be installed in the hollow anchor bolt in the surrounding rock or directly installed in the drilled hole in the surrounding rock. Considering that tunnel frost damage mostly occurs at the arch feet, heat pipes are mainly arranged in the surrounding rock at the arch feet. Embodiment

[0031] As another embodiment of the present invention, the difference between this embodiment and Embodiment 1 is that the heat pipe 1 includes a heat storage heat pipe and a heat release heat pipe. Considering the working principle that the gravity heat pipe can transfer the heat of the evaporation section to the condensation section, the heat storage heat pipe and the heat release heat pipe are arranged at intervals along the tunnel axis at a certain inclination angle. The minimum interval is 1 m. The heat storage heat pipe has a negative inclination angle, and the heat release heat pipe has a positive inclination angle. The inclination angle range is ±15 to 45 degrees to ensure that the condensed working fluid in the heat pipe can flow back to the evaporation section by gravity and conduct cyclic heat transfer. Embodiment

[0032] As another embodiment of the present invention, the difference between this embodiment and Embodiment 1 lies in that the length of the heat pipe 1 is different, including a medium-temperature heat storage heat pipe and a high-temperature heat storage heat pipe. The medium-temperature heat storage heat pipe is installed in the medium-temperature heat storage area of the surrounding rock, and the high-temperature heat storage heat pipe is installed in the high-temperature heat storage area of the surrounding rock. The medium-temperature heat storage area of the surrounding rock is the surrounding rock at a distance of 0-5 m from the surface of the primary lining, and the high-temperature heat storage area of the surrounding rock is the surrounding rock at a distance of 5-10 m from the surface of the primary lining. The operating temperature of the medium-temperature heat storage heat pipe is above 20 °C; the operating temperature of the high-temperature heat storage heat pipe is above 30 °C. Embodiment

[0033] As another embodiment of the present invention, this embodiment is a further optimization based on the above embodiment. After the heat pipe 1 is arranged, a heat insulation layer 6 is laid on the surface of the secondary lining 5 of the tunnel to minimize the heat loss in the surrounding rock 10 to the greatest extent.

[0034] The working principle of the present invention:

[0035] In summer, the process of heat storage in the surrounding rock by the heat storage automatic control system 12 is divided into two steps, that is, first heat storage in the medium-temperature heat storage area and then heat storage in the high-temperature heat storage area. The different heat storage temperatures can be achieved by adjusting the power of the solar heat exchanger 7 by the heat storage automatic control system 12. The specific process is as follows: First, heat storage is carried out in the medium-temperature heat storage area. When the surrounding rock temperature monitoring system measures that the temperature of the surrounding rock in the medium-temperature heat storage area reaches 18-20 °C, the heat storage automatic control system 12 increases the power of the solar heat exchanger 7, so as to carry out heat storage in the high-temperature heat storage area. When the surrounding rock temperature monitoring system measures that the temperature of the surrounding rock in the high-temperature heat storage area reaches 28-30 °C, the heat storage automatic control system 12 turns off the solar heat exchanger 7 and stops heat storage. It should be noted that in actual operation, the change of the surrounding rock temperature will be affected by various factors, such as meteorological conditions, tunnel structure form, materials, etc. Therefore, the specific shutdown temperature needs to be determined according to the actual situation.

[0036] Gravity heat pipes use the principles of gravity and heat conduction to transfer heat energy, and have the advantages of high-efficiency transmission, energy saving, simple maintenance, and adaptability to various environments. By arranging gravity heat pipes with different lengths in the surrounding rock, the heat energy is stored in the surrounding rock at different depths, breaking through the limitation of traditional energy tunnel anti-freezing technology that only extracts geothermal energy near the lining, and can fully utilize the energy storage space of the tunnel surrounding rock.

[0037] The heat pipe and the solar heat exchanger are used to realize cross-seasonal heat storage. In summer, the solar heat exchanger absorbs solar heat energy, and transfers the heat energy into the primary lining of the tunnel through the water distribution pipe and the water collecting pipe, and stores it in the surrounding rock. In winter, the heat energy in the surrounding rock is slowly released to the primary lining of the tunnel through the heat pipe, achieving the effect of self-anti-freezing. This structure realizes the efficient storage and release of heat energy, reduces energy consumption, and has the advantages of high efficiency, environmental protection, and energy saving.

[0038] The above are only the preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims

1. An energy tunnel self - anti - freezing structure based on surrounding rock cross - seasonal heat storage technology, comprising a heat pipe (1), a heat exchange pipeline (2), a solar heat exchanger (7), a surrounding rock temperature monitoring system, and a heat storage automatic control system (12), characterized in that: The solar heat exchanger (7) is installed outside the tunnel and is controlled by the heat storage automatic control system (12); The heat exchange pipeline (2) is buried between the primary lining (3) and the waterproof board (4) of the tunnel along the tunnel length direction, and is connected to the solar heat exchanger (7) through a water distribution pipe (8) and a water collecting pipe (9); One end of the heat pipe (1) is buried into the primary lining (3) of the tunnel, and the other end is buried into the surrounding rock (10). A temperature sensor (11) is installed at the end of the heat pipe (1) close to the surrounding rock (10). All the temperature sensors (11) form a surrounding rock temperature monitoring system; In summer, when the external air temperature of the tunnel rises to a certain temperature, the heat storage automatic control system (12) automatically turns on the solar heat exchanger (7) outside the tunnel. The heat energy absorbed by the solar heat exchanger (7) is then transmitted into the primary lining (3) of the tunnel through the heat exchange pipeline (2) between the primary lining (3) and the waterproof board (4) by the water distribution pipe (8) and the water collecting pipe (9), and the heat energy is stored into the surrounding rock (10) through the heat pipe (1). At the same time, the surrounding rock temperature monitoring system monitors the surrounding rock temperature in real - time. When the surrounding rock (10) reaches a certain temperature, the heat storage automatic control system (12) automatically turns off the solar heat exchanger (7) and stops heat storage; In winter, the heat energy in the surrounding rock (10) is slowly released to the primary lining (3) of the tunnel by the heat pipe (1), so that the temperature of the primary lining (3) rises, achieving the effect of self - anti - freezing.

2. The self-anti-freezing structure of an energy tunnel based on the surrounding rock cross-seasonal heat storage technology according to claim 1, characterized in that: The type of the heat pipe (1) is a gravity heat pipe, which is installed in the hollow rock bolt in the surrounding rock or directly installed in the surrounding rock borehole, and is arranged at the arch foot of the surrounding rock.

3. The self-anti-freezing structure of an energy tunnel based on the surrounding rock cross-seasonal heat storage technology according to claim 2, characterized in that: The heat pipe (1) includes a heat storage heat pipe and a heat - releasing heat pipe. Considering the working principle that the gravity heat pipe can transfer the heat of the evaporation section to the condensation section, the heat storage heat pipe and the heat - releasing heat pipe are arranged at intervals along the tunnel axis with a certain inclination angle when installed. The minimum interval is 1 m. The heat storage heat pipe has a negative inclination angle, and the heat - releasing heat pipe has a positive inclination angle. The inclination angle range is ±15 - 45 degrees to ensure that the condensed working fluid in the heat pipe can flow back to the evaporation section by the action of gravity for cyclic heat transfer.

4. The self - anti - freezing structure of an energy tunnel based on the surrounding rock cross - seasonal heat storage technology according to claim 2, characterized in that: The lengths of the heat pipes (1) are different, including medium - temperature heat storage heat pipes and high - temperature heat storage heat pipes. The medium - temperature heat storage heat pipes are arranged in the medium - temperature heat storage area of the surrounding rock, and the working temperature of the medium - temperature heat storage heat pipes is above 20°C; The high - temperature heat storage heat pipes are arranged in the high - temperature heat storage area of the surrounding rock, and the working temperature of the high - temperature heat storage heat pipes is above 30°C; The medium - temperature heat storage area is the surrounding rock at a distance of 0 - 5 m from the surface of the primary lining, and the high - temperature heat storage area is the surrounding rock at a distance of 5 - 10 m from the surface of the primary lining.

5. The self-anti-freezing structure of an energy tunnel based on the surrounding rock cross-seasonal heat storage technology according to claim 4, characterized in that: After the heat pipes (1) are arranged, a thermal insulation layer (6) is laid on the surface of the secondary lining (5) of the tunnel to reduce the heat loss in the surrounding rock (10).

6. An energy tunnel self - anti - freezing method based on the surrounding rock cross - seasonal heat storage technology, based on the energy tunnel self - anti - freezing structure according to any one of claims 4 to 5 based on the surrounding rock cross - seasonal heat storage technology, characterized in that: In summer, the process of the heat storage automatic control system (12) storing heat in the surrounding rock is divided into two steps, that is, first storing heat in the medium-temperature heat storage area and then storing heat in the high-temperature heat storage area; the different heat storage temperatures are achieved by the heat storage automatic control system (12) adjusting the power of the solar energy heat exchanger (7); the specific process is as follows: First, store heat in the medium-temperature heat storage area. When the surrounding rock temperature monitoring system measures that the surrounding rock temperature in the medium-temperature heat storage area reaches 18 - 20 °C, the heat storage automatic control system (12) increases the power of the solar energy heat exchanger (7), so as to store heat in the high-temperature heat storage area; When the surrounding rock temperature monitoring system measures that the surrounding rock temperature in the high-temperature heat storage area reaches 28 - 30 °C, the heat storage automatic control system (12) shuts down the solar energy heat exchanger (7) and stops heat storage.

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