Summer energy-saving air supply method based on pressure distribution characteristics of public area of subway station hall

Abstract

The application discloses a summer energy-saving air supply method based on pressure distribution characteristics of a subway station hall public area, and comprises the following steps: simulating and researching pressure fluctuation rules of a station hall public area by using a constructed CFD simulation model to obtain a region with strong correlation between the station hall and each entrance pressure fluctuation; in the summer air conditioning season, without changing the total air supply amount of the station hall public area of the subway station, only increasing the mechanical air supply speed of the region with strong correlation between the station hall and each entrance pressure fluctuation, and uniformly reducing the air outlet air supply speed of other regions, the air permeation amount of the entrance can be effectively reduced. Research shows that when the air supply speed of the region with strong correlation between the station hall and each entrance pressure fluctuation is increased by 50%, the total air permeation amount at the entrance can be reduced by 19%. The method can effectively reduce the air permeation amount at the entrance of the subway station in summer, thereby reducing the air conditioning energy consumption of the station environmental control system in summer and realizing energy-saving operation of the station environmental control system.

Description

Technical Field

[0001] This invention relates to a summer energy-saving air supply method based on the pressure distribution characteristics of public areas in subway station halls, and belongs to the field of energy-saving air supply technology for subway stations. Background Technology

[0002] Against the backdrop of dual-carbon development in my country's transportation industry, the demand for energy conservation and emission reduction in subway station ventilation and air conditioning systems is constantly increasing. According to relevant statistics, the operating energy consumption of subway station ventilation and air conditioning systems can reach 40% to 50% of the station's total energy consumption. In summer, when outdoor temperatures are high and station hall temperatures are low, the piston wind effect causes air to circulate between the outdoor area and the station hall through entrances and exits, resulting in significant potential energy consumption for the subway station's environmental control and air conditioning system. Based on field measurements and theoretical calculations, in typical subway stations equipped with platform screen doors, the piston wind effect from trains accounts for approximately 30% to 50% 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 the subway station's environmental control system.

[0003] Currently, existing subway stations often install curtains or air curtains at entrances and exits to reduce airflow infiltration during summer. However, due to the piston-wind effect of trains, conventional air curtains cannot effectively isolate airflow at entrances and exits. Furthermore, air curtains can cause a strong draft, affecting passenger comfort. Therefore, existing methods cannot effectively reduce the impact of the piston-wind effect of trains on airflow infiltration at station entrances and exits. Existing technologies also disclose a device for controlling unorganized air intake at subway station entrances and exits, which effectively utilizes the heat generated on the tracks when a train enters the station to raise the station temperature, while also effectively preventing cold outdoor air from being drawn into the station from the entrances and exits when the train leaves. Other existing technologies propose energy-saving devices and control methods for subway station ventilation and air conditioning systems, installing multi-functional air handling units with air handling and air curtain functions at subway station entrances and exits, which can effectively reduce airflow infiltration at entrances and exits. However, none of these methods effectively reduce energy waste. Summary of the Invention

[0004] The technical problem to be solved by this invention is the increased energy consumption of the air conditioning system caused by a large amount of infiltration air generated at the entrances and exits of the subway station concourse during the summer air-conditioning season.

[0005] To address the aforementioned technical problems, the present invention provides a summer energy-saving air supply method based on the pressure distribution characteristics of public areas in subway station halls, in order to reduce the energy consumption of air conditioning systems caused by infiltration air at entrances and exits. The method is characterized by the following steps:

[0006] Step 1: Establish a CFD simulation model of the subway station concourse level;

[0007] Step 2: Use the CFD simulation model to simulate and analyze the pressure field in the public area of ​​the station hall to obtain the pressure fluctuation law of the station hall; divide the public area of ​​the station hall into planes to obtain the areas of the station hall with strong correlation to the pressure fluctuations of each entrance and exit;

[0008] Step 3: During the air conditioning season, without changing the total air supply volume of the public area in the subway station concourse, uniformly reduce the air supply velocity in other areas and increase the mechanical air supply velocity in areas of the concourse that are strongly correlated with the pressure fluctuations of each entrance and exit, so as to achieve energy saving of the air conditioning system by reducing the infiltration air volume at the entrances and exits.

[0009] Preferably, in step one, load boundary conditions and vent boundary conditions are set for the CFD simulation model, and the accuracy of the model is verified by actual measurement. The verification method is to use the Pearson correlation coefficient to compare and analyze the error between the simulation output results and the measured results. The formula for calculating the Pearson correlation coefficient PCC is as follows:

[0010]

[0011] Among them, E i This represents the i-th test value during the testing period. S is the average of the test values ​​during the test period. i For the i-th simulated value during the test, The average value of the simulated values ​​during the test period; the model is considered accurate when the PCC is greater than or equal to 0.8.

[0012] Preferably, in step two, the criterion for determining that each area of ​​the station hall has a strong correlation with the pressure fluctuation of the entrance / exit is: when the dynamic pressure value of a certain entrance / exit fluctuates, if the fluctuation amplitude of that area is greater than 1.18 times the average fluctuation amplitude of all areas, then that area is considered to have a strong correlation with the pressure fluctuation of that entrance / exit.

[0013] Preferably, in step two, the criterion for determining that each area of ​​the station hall has a strong correlation with the pressure at the entrance / exit is: when the dynamic pressure value of a certain entrance / exit fluctuates, if the fluctuation amplitude of that area is greater than 1.18 to 1.73 times the average fluctuation amplitude of all areas, then that area is considered to have a strong correlation with the pressure fluctuation of that entrance / exit.

[0014] Preferably, in step three, during the air conditioning season, for a standard island-type subway station, the pressure change in the concourse is mainly due to the negative pressure effect, i.e., the increase in the station's cooling load caused by air being drawn from the outside through the entrances and exits. Without changing the total air supply volume of the public area in the subway station concourse, only the mechanical air supply velocity in the area where the pressure of the concourse and the entrances and exits are strongly correlated is increased, while the air supply velocity of other air outlets is uniformly reduced to compensate for the air volume drawn from the outside through the entrances and exits, thereby reducing the infiltration load at the station entrances and exits.

[0015] The advantages of this invention are as follows: The energy-saving air supply method for summer based on the pressure distribution characteristics of the public area of ​​a subway station concourse provided by this invention applies to areas where the pressure fluctuations at the station concourse level and entrances / exits are strongly correlated, effectively reducing the infiltration air volume at entrances / exits. Studies have shown that when the air supply velocity in areas strongly correlated with the pressure at each entrance / exit is increased by 50%, the total infiltration air volume at the entrances / exits can be reduced by 19%. This method can effectively reduce the infiltration air volume at subway station entrances / exits in summer, thereby reducing the air conditioning energy consumption of the station's environmental control system in summer and achieving energy-saving operation of the station's environmental control system. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the physical model of the station hall level;

[0017] Figure 2 This is a comparison chart of simulated and measured wind speeds at entrance / exit 1;

[0018] Figure 3 Floor plan showing the division of public areas on the station concourse level;

[0019] Figure 4 This is a graph showing the change of air dynamic pressure values ​​over time in various areas and entrances / exits of the station hall.

[0020] Figure 5 A diagram illustrating the increased air supply area in the station concourse level;

[0021] Figure 6-1 , Figure 6-2 , Figure 6-3 The data represent the air supply volume control conditions and representative conditions for each inlet / outlet under pressure-related regional conditions at inlets / outlets 1, 2, and 3, respectively. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The embodiments are given for illustrative purposes only and should not be construed as limiting the present invention. The accompanying drawings are for reference and illustration only and do not constitute a limitation on the scope of patent protection of the present invention.

[0023] This embodiment provides a summer energy-saving air supply method based on the pressure distribution characteristics of public areas in subway station halls, specifically including the following steps:

[0024] Step 1: Establish a CFD simulation model of the subway station concourse level.

[0025] Load boundary conditions and air outlet boundary conditions were set for the CFD simulation model, and the accuracy of the model was verified by actual measurement.

[0026] This embodiment conducts on-site measurements and simulation studies on a standard island-type subway station in Shanghai, taking the concourse level as the research object, and establishing a physical model as follows: Figure 1 The station concourse level has three entrances / exits. The physical 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 / exit 1 is 6m wide and 2.5m high, and entrances / exits 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.

[0027] To improve computational efficiency, this embodiment makes appropriate simplifications to the CFD simulation model while ensuring the reliability of the simulation results, and makes the following assumptions: 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 throughout the vent plane; the heat sources in the calculation process, such as the heat dissipation of personnel and the heat dissipation of lighting equipment, are uniformly distributed on their corresponding surfaces; the computational space field does not consider the equipment management rooms and staff rest rooms on both sides of the station hall.

[0028] 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.

[0029] 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.

[0030] To ensure the accuracy of the simulation results, it is necessary to verify and analyze the accuracy of the model simulation. This embodiment uses the Pearson correlation coefficient (PCC) to compare and verify the error between the simulation output and the measured results. The formula for calculating the Pearson correlation coefficient is as follows:

[0031]

[0032] Among them, E i This represents the i-th test value during the testing period. S is the average of the test values ​​during the test period. i For the i-th simulated value during the test, This represents the average value of the simulated values ​​during the test.

[0033] The simulated wind speed results at entrance / exit 1 were compared with the measured results for verification. Figure 2 As shown. According to the Pearson correlation coefficient method, the PCC between the simulated and measured wind speeds at entrance / exit 1 is calculated to be 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 results, it can be concluded that the model in this embodiment is accurate.

[0034] Step 2: Use the CFD simulation model to simulate and analyze the pressure field in the public area of ​​the station hall to obtain the pressure fluctuation law of the station hall. Further divide the public area of ​​the station hall into planes to obtain the areas of the station hall with strong correlation to the pressure fluctuation of each entrance and exit.

[0035] In this embodiment, see Figure 3 The public area of ​​the station hall is divided into planar sections, where Y-1 to Y-4 are the names of the areas on the left side of the station hall, Y-5 to Y-10 are the names of the areas on the right side of the station hall, and Ya to Yh are the names of the areas in the middle of the station hall.

[0036] The dynamic pressure values ​​of the air in various regions at a height of 1.5m inside the station hall and at the entrances / exits were obtained using the CFD simulation model over time. (See attached diagram). Figure 4 The standard used in this embodiment for judging the strong correlation between the pressure of each area on the concourse level and the entrance / exit is as follows: when the dynamic pressure value of a certain entrance / exit fluctuates, if the fluctuation amplitude of that area is greater than 1.18 times the average fluctuation amplitude of all areas, then that area is considered to have a strong correlation with the pressure fluctuation of that entrance / exit. Figure 4It can be seen that the dynamic pressure of the air at the entrances and exits is significantly greater than that of the air in other areas of the station hall. The dynamic pressure of the air at the entrances and exits fluctuates between 0 and 4 Pa, while the dynamic pressure of the air in other areas of the station hall fluctuates between 0 and 1.5 Pa. The dynamic pressure of the air in the central area Ya to Yh of the station hall fluctuates relatively smoothly over time, indicating that the correlation between the pressure fluctuations in the Ya to Yh area and the entrances and exits is relatively small. Therefore, six areas—Y-1, Y-2, Y-4, Y-6, Y-7, and Y-8—are identified as having a strong correlation with the pressure of each entrance and exit. The optimal range for judging the strong correlation between the pressure of each area of ​​the station hall and the entrances and exits is: when the dynamic pressure of a certain entrance or exit fluctuates, if the fluctuation amplitude of that area is greater than 1.18 to 1.73 times the average fluctuation amplitude of all areas, then that area is considered to have a strong correlation with the pressure fluctuation of that entrance or exit.

[0037] Step 3: During the summer air conditioning season, without changing the total air supply volume of the public area of ​​the subway station concourse, only increase the mechanical air supply velocity in the areas of the concourse with strong pressure correlation with each entrance and exit, and uniformly reduce the air supply velocity of the air outlets in other areas, which can effectively reduce the infiltration air volume at the entrances and exits.

[0038] In this embodiment, while maintaining the original total mechanical supply and return air volume, the areas adjacent to the two staircases on the left and right sides of the station hall and the three entrances / exits are, as shown in the example... Figure 5 In the six regions Y-1, Y-2, Y-4, Y-6, Y-7, and Y-8, the air supply velocity was increased by 50%. The simulation results of the infiltration air volume at each inlet and outlet are shown in Figure 6. Table 1 presents the infiltration air volume values ​​at the three inlets and outlets under the pressure-related regional air supply volume control conditions and representative conditions. The data in the table shows that regional air supply has a reducing effect on the infiltration air volume values ​​at the inlets and outlets; the total infiltration air volume at the three inlets and outlets decreased from 24164 m³ / h. 3 It dropped to 19659m 3 The total reduction was 4506m 3 Compared to the total infiltration air volume at the inlet and outlet under the representative operating condition, the total infiltration air volume at the inlet and outlet under the variable zone air supply condition decreased by approximately 19%. This indicates that pressure regulation in areas with strong correlation between air dynamic pressure at each inlet and outlet significantly reduces the infiltration air volume at the inlet and outlet. In other words, increasing the air supply volume of Y-1, Y-2, Y-4, Y-6, Y-7, and Y-8 will significantly reduce the total infiltration air volume at the inlet and outlet, playing a significant role in energy conservation.

[0039] Table 1. Total infiltration air volume values ​​at inlet and outlet under pressure-related regional air volume control conditions and representative conditions.

[0040]

Claims

1. A summer energy-saving air supply method based on the pressure distribution characteristics of public areas in subway station halls, characterized in that, Includes the following steps: Step 1: Establish a CFD simulation model of the subway station concourse level; Step 2: Use the CFD simulation model to simulate and analyze the pressure field in the public area of ​​the station hall to obtain the pressure fluctuation law of the station hall; divide the public area of ​​the station hall into planes to obtain the areas of the station hall with strong correlation to the pressure fluctuations of each entrance and exit; Step 3: During the air conditioning season, without changing the total air supply volume of the public area of ​​the subway station concourse, uniformly reduce the air supply velocity of other areas and increase the mechanical air supply velocity of areas in the concourse that are strongly correlated with the pressure fluctuations of each entrance and exit, so as to achieve energy saving of the air conditioning system by reducing the infiltration air volume at the entrance and exit. In step one, load boundary conditions and vent boundary conditions are set for the CFD simulation model, and the accuracy of the model is verified by actual measurement. The verification method is to use the Pearson correlation coefficient to compare and analyze the error between the simulation output results and the measured results. The formula for calculating the Pearson correlation coefficient PCC is as follows: in, During the testing period i One test value, This represents the average of the test values ​​during the testing period. During the testing period i One simulated value, The average value of the simulated values ​​during the testing period; a PCC greater than or equal to 0.8 is considered to indicate that the model is accurate. In step two, the standard for judging that each area of ​​the station hall has a strong correlation with the pressure fluctuation of the entrance and exit is: when the dynamic pressure value of a certain entrance and exit fluctuates, if the fluctuation amplitude of that area is more than 1.18 times the average fluctuation amplitude of all areas, then that area is considered to have a strong correlation with the pressure fluctuation of that entrance and exit.

2. The summer energy-saving air supply method based on the pressure distribution characteristics of the public area of ​​a subway station hall as described in claim 1, characterized in that, In step two, the standard for judging that each area of ​​the station hall has a strong correlation with the pressure fluctuation of the entrance and exit is: when the dynamic pressure value of a certain entrance and exit fluctuates, if the fluctuation amplitude of that area is greater than 1.18 to 1.73 times the average fluctuation amplitude of all areas, then the area is considered to have a strong correlation with the pressure fluctuation of that entrance and exit.

3. The summer energy-saving air supply method based on the pressure distribution characteristics of the public area of ​​a subway station hall as described in claim 1, characterized in that, In step three, during the air conditioning season, for a standard island-type subway station, the pressure change in the concourse level is mainly due to the negative pressure effect, i.e., the increase in the station's cooling load caused by air being drawn from the outside through the entrances and exits. Without changing the total air supply volume of the public area in the subway station concourse level, only the mechanical air supply velocity in the area where the pressure of the concourse level and the entrances and exits are strongly correlated is increased, while the air supply velocity of other air outlets is uniformly reduced to compensate for the air volume drawn from the outside through the entrances and exits, thereby reducing the infiltration load at the station entrances and exits.

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