Method for reducing subway cooling loss at station during summer off-peak hours

Abstract

The present application relates to a kind of summer off-peak period to reduce the method of subway station cold loss, with subway station station hall as research object, establish the three-dimensional CFD true physical model of subway station station hall;Analysis CFD simulation result, obtain the size order of each entrance and exit permeation wind cold loss in summer off-peak period;In summer off-peak period, without affecting passenger travel and station safe operation premise, to the entrance and exit of larger permeation wind cold loss is closed, i.e. the cold loss of entrance and exit permeation wind can be greatly reduced.Existing research shows that, subway station entrance and exit permeation wind load can account for 40% of the total load of station summer air conditioning system.The present application under the premise of not affecting passenger travel and station safe operation, to the opening and closing control of larger entrance and exit of station cold loss in summer off-peak period, can greatly reduce the cold loss of station, reduce the energy consumption of subway station air conditioning control system, realize the purpose of low carbon, energy-saving operation of subway station.

Description

Technical Field

[0001] This invention relates to an energy-saving technology, and more particularly to a method for reducing cooling loss in subway stations during off-peak summer periods. Background Technology

[0002] With the rapid development of subway construction in my country, the energy consumption of air conditioning systems in subway stations has become increasingly prominent. Subway stations are semi-open buildings; due to the piston wind effect, a large amount of infiltration air is generated at the entrances and exits as trains enter and exit. In summer, when outdoor air temperatures are high and indoor air temperatures are low, the infiltration air load at the entrances and exits significantly increases the air conditioning energy consumption of the station's environmental control system. Field measurements and theoretical calculations show that in typical subway stations with platform screen doors, the infiltration load at the entrances and exits caused by the piston wind effect of trains accounts for approximately 40% of the total air conditioning load in the public area during summer. Therefore, reasonably reducing the infiltration air volume at entrances and exits in summer is of great significance for the low-carbon and energy-saving operation of subway station environmental control systems.

[0003] Existing research primarily focuses on the influencing factors of total airflow at entrances and exits through experimental measurements and theoretical studies, neglecting the impact of infiltration airflow between different entrances and exits. Firstly, during transitional seasons, due to the piston wind effect, a large amount of fresh air can be introduced into the public areas of subway stations through entrances and exits, effectively compensating for the lack of fresh air for station personnel. Secondly, during air-conditioning seasons, the large temperature difference between indoors and outdoors significantly increases the energy consumption of the station's environmental control system due to the increased infiltration airflow at entrances and exits. Furthermore, the different geometrical relationships between entrances / exits and stairwells lead to varying wind speed correlations, resulting in differences in the amount of infiltration airflow at each entrance / exit. Summary of the Invention

[0004] To address the issue of low-carbon and energy-saving operation of the environmental control system in subway stations, a method is proposed to reduce the cooling loss of subway stations during off-peak hours in summer. During off-peak hours in summer, without affecting passenger travel, entrances and exits with large cooling losses due to infiltration air are closed, which effectively reduces the total cooling loss of infiltration air at entrances and exits and reduces the air conditioning energy consumption caused by infiltration air volume at subway station entrances and exits in summer.

[0005] The technical solution of this invention is: a method for reducing cooling loss in subway stations during off-peak hours in summer, specifically including the following steps:

[0006] 1) Measure the wind speed changes at each entrance and exit of the subway station and at the stairwell. Use the wind speed change at the stairwell as the boundary condition to establish a three-dimensional CFD simulation physical model of the subway station concourse. Verify and analyze the accuracy of the numerical simulation model of the concourse through measured data of the wind volume at the entrance and exit.

[0007] 2) Using the aforementioned three-dimensional CFD simulation physical model, considering the fluctuation of infiltration air volume at each entrance and exit due to train entry and exit, the ranking of the station's cooling loss caused by infiltration air at each entrance and exit during the off-peak summer period is obtained.

[0008] 3) Based on the order of the amount of cooling loss caused by infiltration air at each entrance and exit of the subway station, during the off-peak hours in summer, without affecting passenger travel and the safe operation of the station, the entrance and exit with the largest amount of cooling loss caused by infiltration air will be closed to reduce the total cooling loss of infiltration air at the entrance and exit.

[0009] Furthermore, the three-dimensional CFD simulation physical model also sets load boundary conditions and air outlet boundary conditions. The load boundary conditions include the load on the wall, the heat dissipation of the lighting equipment, and the heat dissipation of personnel. The air outlet boundary conditions include the velocity inlet boundary, the pressure outlet boundary, and the air supply and return air outlet boundary of the public area of ​​the station hall.

[0010] Furthermore, in the process of using Airpark to perform physical modeling of the 3D CFD simulation physical model, the following assumptions are made: the air flow in the subway station is an incompressible turbulent steady-state flow and conforms to the Boussineq assumption; in the calculation process, it is assumed that the wind speed direction is perpendicular to the air conditioning vent, and the wind speed remains uniform and constant throughout the entire vent plane; the heat dissipation of personnel and the heat dissipation of lighting equipment are uniformly distributed on their corresponding surfaces during the calculation process; the equipment management rooms and staff rest rooms on both sides of the station hall are not considered in the calculation space field.

[0011] Furthermore, the measured inlet air volume data in step 1) includes the change in air velocity value over the entire continuous time period of train operation.

[0012] Furthermore, the proposed closure scheme for entrances and exits aims to minimize the total loss of infiltration cooling at the entrances and exits, while ensuring that passenger travel and station safety operations are not affected. This scheme involves closing specific entrances and exits.

[0013] The beneficial effects of this invention are as follows: The method of reducing the cooling loss of subway stations during off-peak hours in summer can control the opening and closing of entrances and exits with large infiltration cooling loss during off-peak hours in summer without affecting passenger travel and station safe operation. It is easy to operate, can significantly reduce the cooling loss of infiltration air at entrances and exits, reduce the energy consumption of the subway station environmental control system, and achieve the purpose of low carbon and energy saving. Attached Figure Description

[0014] Figure 1 This is a master plan of the public area of ​​a standard island-style subway station;

[0015] Figure 2 This is a schematic diagram of the physical model of the station hall level;

[0016] Figure 3 This is a schematic diagram comparing the wind speed model at measuring point 1 of the entrance / exit of this invention with the actual measurement.

[0017] Figure 4This is a schematic diagram comparing the wind speed model at the entrance / exit point 2 with the actual measurement of the present invention;

[0018] Figures 5A-5C This is a schematic diagram of the opening and closing of entrances and stairs under three working conditions according to the present invention. Detailed Implementation

[0019] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. These embodiments are based on the technical solution of the present invention and provide detailed implementation methods and specific operating procedures. However, the scope of protection of the present invention is not limited to the following embodiments.

[0020] A method for reducing cooling loss in subway stations during off-peak hours in summer involves temporarily closing certain subway entrances / exits based on the infiltration airflow at the entrances / exits to reduce cooling loss. Specific steps include:

[0021] Step 1: Measure the wind speed changes at each entrance and exit of the subway station and at the stairwells. Use the wind speed changes at the stairwells as boundary conditions to establish a three-dimensional CFD simulation physical model of the subway station concourse. Verify and analyze the accuracy of the numerical simulation model of the concourse level using measured air volume data from the entrances and exits.

[0022] This embodiment takes a standard island platform subway station in Shanghai as the research object. Figure 1 This is a floor plan of the station's public area, which has three entrances leading to the outdoor environment.

[0023] A physical model of the station's passenger movement area was constructed to scale. The model is 102.3m long, 19.64m wide, and 3.4m high (excluding the ceiling). The side staircases are 6m long and 4m wide, the central staircase is 5.5m long and 4m wide, entrance 1 is 6m wide and 2.5m high, and entrances 2 and 3 are 5m wide and 2.5m high. There are 32 air supply vents, each 0.4m long and 0.8m wide, arranged in two rows; and 10 return air vents, each 0.8m long and 0.8m wide. The station physical model is shown below. Figure 2 .

[0024] When using Airpark for physical modeling, the following assumptions are made: the airflow in the subway station is an incompressible turbulent steady-state flow that conforms to the Boussineq assumption; the wind speed direction is assumed to be perpendicular to the air conditioning vents, and the wind speed remains uniform and constant across the entire vent plane; heat sources such as the heat dissipation from people and lighting equipment are uniformly distributed on their corresponding surfaces; the calculation space does not consider the equipment management rooms and staff rest rooms on both sides of the station hall.

[0025] Set load boundary conditions and air outlet boundary conditions for the CFD simulation model.

[0026] In this embodiment, the load boundary conditions include the load on the walls, heat dissipation from lighting equipment, and heat dissipation from personnel. Specifically, the subway station in this embodiment uses an island platform, and the heat generation index per unit area of ​​lighting within the subway station is set at 13 W / m², evenly distributed on the ceiling of the concourse level; the heat flux density of the building envelope is set at 0.47 W / m². 2 The heat dissipation is evenly distributed on the surrounding walls; the heat dissipation of personnel is set at 182W / person, and is evenly distributed on the floor of the station hall.

[0027] In this embodiment, the air outlet boundary conditions include velocity inlet boundary, pressure outlet boundary, and air supply and return air outlet boundaries in the public area of ​​the station hall. Specifically, in this embodiment, the velocity from the platform to the stairwell of the station hall uses a UDF function to define the boundary conditions, with a measured temperature of 17℃ and a turbulence intensity of 10%; the inlet and outlet are pressure boundary outlets with a measured temperature of 14℃; the air supply air outlet in the station hall has a supply air velocity of 3.6m / s and a measured temperature of 17℃; the air return air outlet in the station hall has a return air velocity of 5.3m / s, and the return air volume is calculated according to the standard that the fresh air volume is not less than 10% of the supply air volume in the simulation.

[0028] The measured data in this embodiment include the changes in air velocity values ​​at the three staircases from the platform to the concourse and the three entrances / exits from the concourse to the outside of the subway station throughout the entire continuous time period of train operation. During the measurement, the mechanical supply and return air system of the public area of ​​the subway station was activated, while the upper and lower heat exhaust systems and the intermediate air valves were closed.

[0029] The measured results were compared and analyzed with the simulation results obtained using the CFD simulation model. The results are shown in the figure. Figure 3 and Figure 4 The Pearson correlation coefficient (PCC) was used to compare and verify the error between the simulated output and the measured results. According to the Pearson correlation coefficient method, the PCC between the measured and simulated data at measurement point 1 was calculated to be 0.83, and the PCC between the measured and simulated data at measurement point 2 was 0.87. Based on the statement that a PCC greater than or equal to 0.8 indicates a high correlation between the measured and simulated data, this demonstrates the accuracy of the model.

[0030] Step 2: Using the aforementioned three-dimensional CFD simulation physical model, considering the fluctuation of infiltration air volume at each entrance and exit due to train entry and exit, the ranking of the station's cooling loss caused by infiltration air at each entrance and exit during the off-peak summer period is obtained.

[0031] Using the aforementioned three-dimensional CFD simulation physical model, the infiltration air volume at each entrance / exit during a single train journey cycle in the summer off-peak period was obtained. See Table 1 for the infiltration air volume values ​​and percentages at each entrance / exit. Table 1 shows that entrance / exit 1 has the largest infiltration air volume and percentage, with an infiltration air volume of 14.28 m³ / s. 3 / s, accounting for 40%, followed by entrance / exit 2, and entrance / exit 3 is the smallest.

[0032] Table 1

[0033]

[0034]

[0035] Step 3: Based on the magnitude of the cooling loss caused by infiltration air at each subway station entrance / exit, during off-peak hours in summer, and without affecting passenger travel and station safety, implement the plan to close the entrance / exit that causes the greatest cooling loss due to infiltration air, in order to reduce the total cooling loss caused by infiltration air at the entrance / exit. (Reason for modification: The original description of "significantly large" was an unclear technical feature.)

[0036] The following three working conditions are set for the number of entrances / exits and stairs to be opened, as shown in Figure 5: Working condition 1: representative working condition, stairs 1, stairs 2, stairs 3 and three entrances / exits are all open;

[0037] Condition 2: Stairs 2 and 3 are open, stair 1 is closed, and all three entrances / exits are open;

[0038] Operating Condition 3: Stairs 2 and 3 are open, stair 1 is closed, entrances 2 and 3, which are closer to stair 1, are open, and entrance 1, which is closer to stair 2, is closed.

[0039] The infiltration air volume at each inlet and outlet under various operating conditions was simulated using a three-dimensional CFD simulation physical model. The results are shown in Table 2. From the infiltration air volume values ​​at each inlet and outlet under different operating conditions in Table 2, it can be seen that the infiltration air volume at the three inlets and outlets in operating condition one (with all three inlets and outlets and two staircases fully open) is the maximum value among the five operating conditions, reaching 24164 m³ / s. 3 Secondly, the second scenario involves opening three entrances / exits and staircase 2, with a length of 12200m. 3 The smallest is condition three, which involves opening entrance / exit 2, entrance / exit 3, and staircase 2, with a value of 11410m. 3 This indicates that when all entrances / exits and staircases are open, the total infiltration air volume at the entrances / exits is the largest. When only one staircase is open and all entrances / exits are open, the total infiltration air volume at the entrances / exits in condition 2 (staircase 2) is relatively small. When only one staircase is open and entrance / exit 1 is closed, the infiltration air volume is the smallest, with a total infiltration air volume at the entrances / exits being 53% less than in condition 1. Therefore, from the perspective of reducing the cooling loss of infiltration air at entrances / exits, when the passenger flow in the subway station is low, it is advisable to close entrance / exit 1 to reduce the total cooling loss of infiltration air at the entrances / exits, thereby achieving the goal of energy saving.

[0040] Table 2

[0041]

[0042]

[0043] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for reducing cooling loss in subway stations during off-peak hours in summer, characterized in that, Specifically, the steps include the following: 1) Measure the wind speed changes at each entrance and stairwell of the subway station. Use the wind speed change at the stairwell as the boundary condition to establish a three-dimensional CFD simulation physical model of the subway station concourse. Verify and analyze the accuracy of the numerical simulation model of the concourse through measured data of the entrance and exit air volume. 2) Using the aforementioned three-dimensional CFD simulation physical model, considering the fluctuation of infiltration air volume at each entrance and exit due to train entry and exit, the ranking of the station's cooling loss caused by infiltration air at each entrance and exit during the off-peak summer period is obtained. 3) Based on the order of the amount of cooling loss caused by infiltration air at each entrance and exit of the subway station, during the off-peak hours in summer, without affecting passenger travel and station safety operation, the entrance and exit with the largest amount of cooling loss caused by infiltration air will be closed to reduce the total cooling loss of infiltration air at the entrance and exit. The three-dimensional CFD simulation physical model also sets load boundary conditions and air outlet boundary conditions. The load boundary conditions include the load on the wall, the heat dissipation of the lighting equipment, and the heat dissipation of personnel. The air outlet boundary conditions include the velocity inlet boundary, the pressure outlet boundary, and the air supply and return air outlet boundary of the public area of ​​the station hall.

2. The method for reducing cooling loss in subway stations during off-peak hours in summer according to claim 1, characterized in that, When using Airpark to perform physical modeling of the 3D CFD simulation physical model in step 1), the following assumptions are made: the airflow in the subway station is an incompressible turbulent steady-state flow and conforms to the Boussineq assumption; during the calculation, it is assumed that the wind speed direction is perpendicular to the air conditioning vents and the wind speed remains uniform and constant across the entire vent plane; the heat dissipation of personnel and lighting equipment is uniformly distributed on their corresponding surfaces during the calculation; the equipment management rooms and staff rest rooms on both sides of the station hall are not considered in the calculation space field.

3. The method for reducing cooling loss in subway stations during off-peak hours in summer according to claim 1 or 2, characterized in that, Step 1) Verifying the accuracy of the numerical simulation model of the station hall through measured entrance and exit air volume data, the measured entrance and exit air volume data includes the air velocity values ​​of the three staircases from the platform to the station hall and the three entrances from the station hall to the outside of the subway station as a function of the entire continuous time period of train operation.

4. The method for reducing cooling loss in subway stations during off-peak hours in summer according to claim 1, characterized in that, The proposed closure scheme for entrances and exits aims to minimize the total loss of infiltration air cooling at the entrances and exits, while ensuring that passenger travel and station safety operations are not affected. This scheme involves closing specific entrances and exits.

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