Active cold storage subway tunnel thermal environment energy-saving regulation system and method

Abstract

The application discloses a kind of active cold storage subway tunnel thermal environment energy-saving regulation and control system and method, and pipe piece heat exchanger is arranged in tunnel pipe piece ring, heat of surrounding soil layer of tunnel is extracted out by heat exchange medium in winter, realize the temperature of surrounding soil layer of tunnel is reduced, reach the purpose of cold storage for summer, and the heat extracted out can be used for the heating of surrounding building after being extracted by heat pump.The system of the application can significantly reduce the energy consumption of ventilation and air conditioning in summer, and can further reduce the heat accumulation of tunnel operation in summer, overcome the problems of large energy consumption, poor effect, high cost and easy heat accumulation of traditional subway tunnel environmental control system, the application has wide application range, low cost and operating cost, energy saving, effectively solves the problem of waste heat accumulation in subway tunnel, and turns waste into treasure, reduces energy consumption, is technically feasible, effective, economical, more specific and close to objective reality, and has significant engineering practical significance.

Description

Technical Field

[0001] This invention relates to the field of thermal environment control in subway tunnels, specifically to an active cooling energy-saving thermal environment control system and method for subway tunnels. Background Technology

[0002] Long-term operation of subways leads to a continuous deterioration of the thermal environment within the tunnels, potentially affecting their normal operation. For example, the London Underground, with over 150 years of history, has seen tunnel temperatures rise from 14°C at construction to 30°C in the early 21st century due to train operation, with extreme temperatures even reaching 40°C inside carriages. The accumulation of waste heat in the tunnels causes heat buildup, leading to a deterioration of the underground thermal environment. This not only severely impacts the thermal comfort of passengers but also results in significant energy consumption. With the development of subways, thermal environment control has become increasingly important. Subway train operation generates a large amount of heat, and the storage and dissipation of this heat are crucial for addressing the subway's thermal environment. During operation, stations use air conditioning systems for cooling, while tunnel cooling relies on the "piston effect" of train movement or mechanical ventilation carrying some of the station's air conditioning cool air. Due to the large volume of subway tunnels, high-power ventilation equipment is required, resulting in significant energy consumption and high costs.

[0003] The "Code for Design of Metro Tunnels" (GB-50157-2013) states that the soil layer surrounding a metro station is a large heat-absorbing body, which regulates the ambient temperature inside the tunnel. In summer, the soil layer absorbs heat from the tunnel air, thus lowering the tunnel air temperature; conversely, in winter, it releases heat into the tunnel air. Patent application CN201911236800.2, published on December 5, 2019, entitled "An Active Cooling System and Method for Metro Tunnels," discloses an active cooling system and method for metro tunnels. This system uses temperature sensors arranged within the surrounding rock to determine if the tunnel is overheating. It then controls heat exchangers embedded in the surrounding rock to extract heat and store this heat energy, releasing it when necessary to reduce the tunnel temperature and cool the tunnel. The system and method have shortcomings in cooling tunnels. In summer, the temperature inside the tunnel is high and the heat exchanger has low heat extraction efficiency, so it is questionable whether it can cool the tunnel. In winter, the temperature inside the tunnel is not high, and the purpose of cooling the tunnel can be achieved by exchanging heat between the tunnel wall and the air inside the tunnel. Furthermore, it is difficult to place temperature sensors in the surrounding rock of the above system, and the extracted heat energy is lost during storage. Summary of the Invention

[0004] The technical problem this invention aims to solve is to provide an active cooling storage thermal environment energy-saving control system and method for subway tunnels, addressing the shortcomings of existing technologies. This invention arranges segment heat exchangers within the tunnel segment ring. In winter, heat is extracted from the surrounding soil layer through a heat exchange medium, lowering the temperature of the surrounding soil and achieving cooling storage for summer. Simultaneously, the extracted heat can be used for heating surrounding buildings after being extracted by a heat pump. Due to the temperature drop in the surrounding soil layer, this system significantly reduces energy consumption for ventilation and air conditioning in summer, and further reduces heat accumulation during tunnel operation. It overcomes the problems of high energy consumption, poor performance, high cost, and heat accumulation associated with traditional subway tunnel environmental control systems. This invention has a wide applicability, low cost and operating expenses, and saves energy. It effectively solves the problem of waste heat accumulation in subway tunnels while turning waste into valuable resources and reducing energy consumption.

[0005] The technical solution adopted by this invention to solve the above-mentioned technical problems is as follows: an active cold storage thermal environment energy-saving control system for subway tunnels, comprising a heat extraction unit and a monitoring unit. The heat extraction unit includes a circulating water pump, a main inlet pipe, a main outlet pipe, multiple sets of ring-type tube-plate heat exchangers, a heat pump, and heating equipment. The heating equipment is connected to the heat pump. The outlet end of the heat pump is connected to the inlet end of the main inlet pipe via the circulating water pump, and the outlet end of the main outlet pipe is connected to the inlet end of the heat pump. Multiple sets of the tube-plate heat exchangers... On the soil-facing side of the tunnel segment ring, multiple sets of segment heat exchangers are arranged along the tunnel axis. Each set of segment heat exchangers is arranged circumferentially along the tunnel. The inlet end of each set of segment heat exchangers is connected to the main water inlet pipe, and the outlet end of each set of segment heat exchangers is connected to the main water outlet pipe. A first shut-off valve is installed on the main water inlet pipe, and a second shut-off valve is installed on the main water outlet pipe. The monitoring unit includes a first in-pipe fluid temperature sensor, an in-pipe flow sensor, and a second in-pipe fluid temperature sensor. The system comprises a sensor, multiple sets of combined sensors, a signal processor, and a control unit. The first in-pipe fluid temperature sensor and the in-pipe flow sensor are installed on the main inlet pipe near its inlet end. The second in-pipe fluid temperature sensor is installed on the main outlet pipe near its outlet end. The multiple sets of combined sensors are spaced apart on the tunnel wall. These sensors monitor the air temperature, tunnel wall temperature, and air velocity within the tunnel. The first in-pipe fluid temperature sensor, the in-pipe flow sensor, the second in-pipe fluid temperature sensor, and the multiple sets of combined sensors are connected to the signal processor via transmission lines. The signal processor is connected to the control unit. The control unit is connected to the heat pump and the circulating water pump via transmission lines. The control unit collects signals from each sensor and sends commands to the control unit. The control unit controls the operation of the circulating water pump and the heat pump according to the commands from the signal processor.

[0006] An energy-saving control method for the thermal environment of a subway tunnel using the above-mentioned system with active cold storage includes the following steps:

[0007] 1) Based on the air temperature t inside the tunnel collected by multiple sets of combined sensors from June to August in summer. f The wall temperature t inside the tunnel s Given the air velocity v inside the tunnel, the total heat gain of the soil layer surrounding the tunnel in summer is calculated as follows:

[0008]

[0009] In equation (1), L is the length of the tunnel, and h wis the heat transfer coefficient of the inner wall of the tunnel, τ is the time from June to August of the current year, p is the perimeter of the cross section of the inner wall of the tunnel, wherein:

[0010] h w =3.06v+4.11 (2)

[0011] 2) In winter, the system is turned on, according to the temperature T collected by the first fluid temperature sensor in the pipe in and the temperature T collected by the second fluid temperature sensor in the pipe out and the flow m collected by the flow sensor in the pipe f , the cumulative heat exchange of multiple groups of segment heat exchangers with the soil around the tunnel from December in winter to February of the next year is calculated as:

[0012] Q2=∑m f c ρ (T out -T in ) (3)

[0013] In formula (3), c ρ is the specific heat capacity of the fluid in the pipe;

[0014] 3) The system operation is judged according to the magnitudes of Q2 and Q1. In winter, the control unit sends instructions to the circulating water pump and the heat pump to start the operation of the circulating water pump and the heat pump. When Q2<Q1, the system operates normally and supplies heat to the heating equipment; when Q2>Q1, the control unit sends instructions to the circulating water pump and the heat pump to stop the operation of the circulating water pump and the heat pump, and the system is shut down. If there is a heating demand, the system is manually turned on to supply heat to the heating equipment.

[0015] Compared with the prior art, the present invention has the following advantages:

[0016] (1) The conventional environmental control system of a subway tunnel delivers cooling capacity to the interval tunnel, which has high energy consumption, poor effect, and high construction and operation costs. In winter, the system of the present invention extracts and utilizes the heat from the soil around the tunnel by using the heat exchange medium in the segment heat exchanger, which plays a role of reducing the ground temperature and storing cold for summer, thereby reducing the cooling capacity of the subway tunnel in summer, that is, reducing the energy consumption of ventilation and air conditioning of the subway tunnel in summer, achieving the purposes of reducing the energy consumption of thermal environment control of the subway tunnel and improving the thermal environment of the subway. The invention has wide application range, low cost and operation cost, saves energy, can turn waste into treasure and reduce energy consumption while effectively solving the problem of waste heat accumulation in the subway tunnel. Today, with the vigorous development of subway construction in China, the invention has broad application prospects and great development potential.

[0017] (2) The present invention extracts geothermal energy from the soil layer around the tunnel and raises it to the heating equipment via a heat pump. It can be used for winter heating of surrounding buildings, reducing carbon dioxide emissions and turning harm into benefit. It is of great significance for achieving the dual carbon plan of "carbon neutrality and carbon peak".

[0018] (3) The system of the present invention directly extracts the geothermal energy of the soil layer around the tunnel, which is technically feasible, effective, and economically economical. It is more specific and closer to objective reality, and has significant practical engineering significance. Attached Figure Description

[0019] Figure 1 This is a partial longitudinal section schematic diagram of the active cooling storage thermal environment energy-saving control system for subway tunnels in Example 1;

[0020] Figure 2 This is a partial cross-sectional schematic diagram of the active cooling storage thermal environment energy-saving control system for subway tunnels in Example 1;

[0021] Figure 3 This is a schematic diagram of the arrangement of a set of tube-segment heat exchangers in Example 1. Detailed Implementation

[0022] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments.

[0023] Example 1: An active cooling storage thermal environment energy-saving control system for subway tunnels, such as... Figures 1-3 As shown, the system includes a heat extraction unit and a monitoring unit. The heat extraction unit includes a circulating water pump 1, a main inlet pipe 2, a main outlet pipe 3, multiple sets of ring-type tube-plate heat exchangers 4, a heat pump 5, and heating equipment 6. The heat exchange medium within the heat extraction unit is tap water. Figure 1 and Figure 3 The middle arrow indicates the direction of tap water flow. Heating equipment 6 is connected to heat pump 5. The outlet of heat pump 5 is connected to the inlet of main water inlet pipe 2 via circulating water pump 1. The outlet of main water outlet pipe 3 is connected to the inlet of heat pump 5. Multiple sets of tube segment heat exchangers 4 are buried on the soil-facing side within the tunnel segment ring 8. These multiple sets of tube segment heat exchangers 4 are constructed in conjunction with the subway shield tunneling method and are arranged along the tunnel axis. Figure 1Only one set of tube-plate heat exchangers 4 is shown. Each set of tube-plate heat exchangers 4 is arranged circumferentially along the tunnel. The inlet end of each set of tube-plate heat exchangers 4 is connected to the main water inlet pipe 2, and the outlet end of each set of tube-plate heat exchangers 4 is connected to the main water outlet pipe 3. A first shut-off valve 21 is installed on the main water inlet pipe 2, and a second shut-off valve 31 is installed on the main water outlet pipe 3. The monitoring unit includes a first in-pipe fluid temperature sensor 71, an in-pipe flow sensor 73, a second in-pipe fluid temperature sensor 72, multiple sets of combined sensors 74, a signal processor 75, and a control unit 76. The first in-pipe fluid temperature sensor 71 and the in-pipe flow sensor 73 are installed on the main water inlet pipe 2 and close to the inlet end of the main water inlet pipe 2. The second in-pipe fluid temperature sensor 72 is installed on the main water outlet pipe 3. Near the outlet end of the main water outlet pipe 3, multiple sets of combined sensors 74 are arranged on the inner wall of the tunnel. These sensors monitor the air temperature, the wall temperature, and the air velocity within the tunnel. A first in-pipe fluid temperature sensor 71, an in-pipe flow sensor 73, a second in-pipe fluid temperature sensor 72, and the combined sensors 74 are connected to a signal processor 75 via transmission lines. The signal processor 75 is connected to a control unit 76, which is connected to a heat pump 5 and a circulating water pump 1 via transmission lines. The signal processor 75 collects signals from each sensor and sends commands to the control unit 76. The control unit 76 controls the operation of the circulating water pump 1 and the heat pump 5 according to the commands from the signal processor 75. In this embodiment, the combined sensors 74 are commercially available products, the signal processor 75 is a commercially available PLC controller, and the control unit 76 is a commercially available switch controller.

[0024] This invention arranges the segment heat exchanger 4 within the tunnel segment ring 8. In winter, it extracts heat from the surrounding soil layer through the heat exchange medium, thereby lowering the temperature of the surrounding soil layer and achieving the purpose of storing cold for summer. Simultaneously, the extracted heat can be used for heating surrounding buildings after being extracted by the heat pump 5. Due to the decrease in the temperature of the surrounding soil layer, the system of this invention can significantly reduce the energy consumption of the environmental control system's ventilation and air conditioning in summer, and can also further reduce heat accumulation during tunnel operation in summer.

[0025] Example 2: An active cold storage thermal environment energy-saving control method for subway tunnels implemented using the system of Example 1, comprising the following steps:

[0026] 1) Based on the air temperature t inside the tunnel collected by multiple sets of combined sensors from June to August in summer. f The wall temperature t inside the tunnel s Given the air velocity v inside the tunnel, the total heat gain of the soil layer surrounding the tunnel in summer is calculated as follows:

[0027]

[0028] In formula (1), L is the length of the tunnel, h w is the heat transfer coefficient of the inner wall of the tunnel, τ is the time from June to August of the current year, p is the cross-sectional perimeter of the inner wall of the tunnel, wherein:

[0029] h w =3.06v+4.11 (2)

[0030] 2) In winter, the system is turned on, and according to the temperature T collected by the first fluid temperature sensor in the pipe in and the temperature T collected by the second fluid temperature sensor in the pipe out and the flow rate m collected by the flow sensor in the pipe f , the cumulative heat exchange amount between multiple sets of segment heat exchangers and the soil layer around the tunnel from December in winter to February of the next year is calculated as:

[0031] Q2=∑m f c ρ (T out -T in ) (3)

[0032] In formula (3), c ρ is the specific heat capacity of the fluid in the pipe;

[0033] 3) The system operation status is judged according to the magnitudes of Q2 and Q1. In winter, the control unit sends instructions to the circulating water pump and the heat pump to start the operation of the circulating water pump and the heat pump. When Q2<Q1, the system operates normally and supplies heat to the heating equipment; when Q2>Q1, the control unit sends instructions to the circulating water pump and the heat pump to stop the operation of the circulating water pump and the heat pump, and the system is shut down. If there is a heating demand, the system is manually turned on to supply heat to the heating equipment. It should be noted that when starting the circulating water pump and the heat pump, the circulating water pump shall be started first, and then the heat pump; when shutting down the circulating water pump and the heat pump, the circulating water pump shall be shut down first, and then the heat pump.

Claims

1. An active cold storage thermal environment energy-saving control system for subway tunnels, characterized in that, Comprising a heat extraction unit and a monitoring unit, wherein the heat extraction unit comprises a circulating water pump, a main water inlet pipe, a main water outlet pipe, a plurality of groups of annular segment heat exchangers, a heat pump and heating equipment, the heating equipment is connected to the heat pump, an outlet end of the heat pump is connected to an inlet end of the main water inlet pipe via the circulating water pump, an outlet end of the main water outlet pipe is connected to an inlet end of the heat pump, the plurality of groups of segment heat exchangers are embedded in the soil-facing side of a tunnel segment ring, the plurality of groups of segment heat exchangers are arranged along the axis direction of the tunnel, each group of segment heat exchangers is arranged along the circumferential direction of the tunnel, an inlet end of each group of segment heat exchangers is connected to the main water inlet pipe, an outlet end of each group of segment heat exchangers is connected to the main water outlet pipe, a first stop valve is arranged on a pipeline of the main water inlet pipe, a second stop valve is arranged on a pipeline of the main water outlet pipe, the monitoring unit comprises a first in-pipe fluid temperature sensor, an in-pipe flow sensor, a second in-pipe fluid temperature sensor, a plurality of groups of combined sensors, a signal processor and a control unit, the first in-pipe fluid temperature sensor and the in-pipe flow sensor are arranged on the pipeline of the main water inlet pipe and close to the inlet end of the main water inlet pipe, the second in-pipe fluid temperature sensor is arranged on the pipeline of the main water outlet pipe and close to the outlet end of the main water outlet pipe, the plurality of groups of combined sensors are arranged at intervals on the inner wall of the tunnel, the plurality of groups of combined sensors are used for monitoring the air temperature in the tunnel, the wall surface temperature of the tunnel inner wall and the air flow velocity in the tunnel, the first in-pipe fluid temperature sensor, the in-pipe flow sensor, the second in-pipe fluid temperature sensor and the plurality of groups of combined sensors are respectively connected to the signal processor via transmission lines, the signal processor is connected to the control unit, the control unit is respectively connected to the heat pump and the circulating water pump via transmission lines, the control unit is used for collecting signals sent by each sensor and sending instructions to the control unit, and the control unit is used for controlling the operating states of the circulating water pump and the heat pump according to the instructions sent by the signal processor.

2. A method for energy-saving control of the thermal environment of a subway tunnel using active cold storage implemented with the system described in claim 1, characterized in that, comprises the following steps: 1) Based on the air temperature t inside the tunnel collected by multiple sets of combined sensors from June to August in summer. f The wall temperature t inside the tunnel s Given the air velocity v inside the tunnel, the total heat gain of the soil layer surrounding the tunnel in summer is calculated as follows: In equation (1), L is the length of the tunnel, and h w Let be the heat transfer coefficient of the tunnel inner wall, τ be the time from June to August of that year, and p be the cross-sectional perimeter of the tunnel inner wall, where: h w =3.06v+4.11 (2) 2) In winter, turn on the system and use the temperature T collected by the fluid temperature sensor in the first pipe. in The temperature T collected by the fluid temperature sensor inside the second tube out and the flow rate m collected by the in-pipe flow sensor f The cumulative heat exchange between multiple sets of segment heat exchangers and the surrounding soil layer during the winter months of December to February of the following year is calculated as follows: Q2=∑m f c ρ (T out -T in ) (3) In equation (3), c ρ This is the specific heat capacity of the fluid inside the pipe; 3) Determining the operation condition of the system according to the magnitudes of Q2 and Q1: in winter, the control unit sends instructions to the circulating water pump and the heat pump to start the operation of the circulating water pump and the heat pump; when Q2 < Q1, the system operates normally and supplies heat to the heating equipment; when Q2 > Q1, the control unit sends instructions to the circulating water pump and the heat pump to stop the operation of the circulating water pump and the heat pump, and the system is shut down; if there is a heating demand, the system is manually started to supply heat to the heating equipment.

Images