Rail transit carriage fresh air volume management method based on passive sampling technology

Abstract

The invention discloses a rail transit carriage fresh air volume management method based on a passive sampling technology, and the method comprises the steps: obtaining the concentration information of key gas pollutants, such as carbon dioxide and formaldehyde, at different heights and in different regions in a carriage through an air passive sampling device, and obtaining the fresh air volume of the carriage according to the monitored actual pollutant concentration change condition; according to the method, the appropriate fresh air ratio adjusting value is calculated according to the specific time periods of workdays and holidays in combination with the limit value requirements in relevant national health specifications, and the fresh air ratios in different time periods are adjusted according to the fresh air ratio adjusting value, so that the power consumption of the subway air conditioning system can be remarkably reduced, the operation cost is further saved, and the method conforms to the green and energy-saving development trend.

Description

Technical Field

[0001] The present invention relates to the technical field of environmental monitoring, and in particular to a method for managing fresh air volume in a rail transit carriage based on a passive sampling technology. Background Art

[0002] Rail transit, especially subways, has become the main carrier of public transportation in large cities due to its advantages such as large capacity, high efficiency and low energy consumption. However, the microenvironment of subway cars is relatively special, with high population density and high mobility, relatively closed space and insufficient forced ventilation. Pollutants brought in by the vehicle's own ventilation system, released by materials inside the car and generated by the activities of people inside the car, such as volatile organic compounds, formaldehyde, carbon dioxide, ammonia, etc., cannot be quickly discharged from the car, posing a health hazard to commuters and subway drivers.

[0003] Studies have shown that the introduction of fresh air can effectively reduce the concentration of gaseous pollutants in rail transit carriages. At present, the industry mainly calculates the amount of fresh air that needs to be introduced into the system according to the minimum amount of fresh air required per person per hour in the carriage. In fact, this method of fresh air volume management is extremely extensive. On the one hand, statistical results show that the current fresh air energy consumption is a large part of the power consumption of the subway air conditioning system, generally accounting for more than 40%; on the other hand, the fresh air volume in this method is only related to the actual number of passengers, and does not form a correlation with the pollutant concentration limit in the relevant national health regulations. This may not only lead to high energy consumption of the fresh air system, but also lead to the actual pollutant concentration in the carriage not meeting the standard. This is mainly because the actual number of passengers in the subway carriage is difficult to accurately count, and some pollutants mainly from non-human emission sources are not strongly correlated with the actual number of passengers in the carriage; secondly, even for pollutants directly related to the human body, such as carbon dioxide, the concentration in the carriage does not decrease rapidly with the decrease in passenger flow, but slowly decreases with a certain accumulation hysteresis; thirdly, affected by the airflow organization form, the pollutant concentration distribution in the carriage is not uniform, and the pollutant concentration monitoring results with a narrow coverage are not representative. Therefore, the reasonable amount of fresh air intake in the car should not be roughly estimated based on the number of passengers in the car during peak or non-peak operating hours, but should be based on ensuring that the pollutant concentration in the car does not exceed the standard under different operating conditions, so as to achieve the purpose of both satisfying the comfort of the passengers and reducing the energy consumption of the car. This requires comprehensive and accurate air quality monitoring results in the car as a scientific basis.

[0004] There are two main methods for monitoring rail carriage air quality. One is to use active sampling and analysis or direct sampling and detection with portable equipment. This method requires setting up samplers or detection equipment at designated heights at representative points in the carriage. The noise and vibration generated affect the normal operation of the train, which is inconvenient. In addition, it is limited by the number of equipment and the cost of electricity. The representativeness of this monitoring method is limited, the time and space coverage is insufficient, and the monitoring results are insufficient to guide the optimization of carriage ventilation. The other method is to install an air quality monitoring system in the carriage. Although real-time online monitoring can be achieved, it is difficult to capture the distribution characteristics of pollutant concentrations at different spatial locations due to the cost of sensors. The installation of the monitoring system requires a lot of cost investment and modification of the original car body. Long-term operation or frequent adjustment of the operating conditions of the ventilation system also makes the energy consumption of the entire system high, which does not meet the green needs of energy saving and carbon reduction.

[0005] Passive sampling is a method based on the principle of gas molecule diffusion or permeation to collect gaseous or vapor pollutants in the air. It is low-cost, does not require power and pumping power, and has high spatial and temporal coverage. It is also called pumpless sampling technology. Passive sampling can be used for SO according to the different absorption layers, such as quantitative filter paper or non-woven fabrics impregnated with chemical reagents, solid adsorbents such as activated carbon particles, etc. 2 、NO 2 , CO 2 NH 3 , O 3 , HF and other gas molecules. Summary of the invention

[0006] In order to solve the problems existing in the above-mentioned prior art, the present invention provides a method for managing the fresh air volume in a rail transit carriage based on a passive sampling technology, which mainly includes:

[0007] Select several measurement carriages in the train, arrange air passive sampling devices at preset monitoring positions in the measurement carriages, obtain air samples, and obtain air information at different monitoring positions in the measurement carriages;

[0008] According to the air information obtained at different monitoring positions, the average concentration of one of the gases in the air information of a single measuring compartment is calculated to obtain the average concentration of the characteristic gas. According to the average concentration of the characteristic gas in several measuring compartments, the average concentration of the characteristic gas of the whole train is calculated.

[0009] The fresh air ratio adjustment value is calculated based on the average value of the characteristic gas concentration of the entire train and the air supply volume of the train's fresh air system, and fresh air volume management measures are generated.

[0010] Preferably, the measured carriages include head / tail carriages and middle carriages, wherein the number of carriages in the middle carriages is greater than the number of carriages in the head / tail carriages.

[0011] Preferably, a single measurement carriage includes four monitoring points, which are respectively arranged at a height of 1.6m near the door, 1.1m in the middle of the carriage, 1.6m in the middle of the carriage, and at the return air outlet under the seat, marked as P1, P2, P3, and P4 respectively.

[0012] Preferably, according to the air information obtained at different monitoring positions, the average concentration of one of the gases in the air information of a single measured compartment is calculated to obtain the average characteristic gas concentration:

[0013] Set the weight coefficient k for the four monitoring points P1, P2, P3, and P4 respectively 1 , k 2 , k 3 , k 4 , and k 2 =k 3 >k 1 >k 4 , through formula C (ω)j =k 1 ×C P1 +k 2 ×C P2 +k 3 ×C P3 +k 4 ×C P4 Calculate the average concentration of the characteristic gas in the measured compartment, where ω is the characteristic gas, j is the compartment number, C P1 , C P2 , C P3 , C P4 They are the characteristic gas concentration values ​​corresponding to the monitoring points P1, P2, P3 and P4 in the carriage respectively.

[0014] Preferably, k 1 =0.2, k 2 =0.35, k 3 =0.35, k 4 =0.1.

[0015] Preferably, the average characteristic gas concentration of the entire train is calculated based on the average characteristic gas concentrations in the several measured carriages:

[0016] By formula Calculate the average value of characteristic gas concentration of the whole train, where Ti is the time period of measurement, n is the total number of train carriages, and C (ω)头 is the average value of characteristic gas concentration in the head / tail compartment, C (ω)中 It is the average value of characteristic gas concentration in the middle compartment.

[0017] Preferably, the fresh air ratio adjustment value is calculated according to the average value of the characteristic gas concentration of the whole train and the air supply volume of the train fresh air system, and the fresh air volume management measures are generated:

[0018] The concentration of characteristic gases in the train fresh air system is detected to obtain the characteristic gas concentration value in the fresh air. Calculate the fresh air ratio adjustment value, where C s is the safety threshold of characteristic gas concentration in the car, C 0 is the characteristic gas concentration value in the train fresh air; V 车 is the volume of the train compartment, V 送 It is to measure the total air supply volume in the car during the period, calculate the fresh air ratio adjustment values ​​of several characteristic gases, select the fresh air ratio adjustment value with the largest value, and generate fresh air volume management measures.

[0019] Preferably, the characteristic gas is one of carbon dioxide, ammonia, total volatile organic compounds and formaldehyde.

[0020] The technical solution provided by the embodiment of the present invention may have the following beneficial effects:

[0021] The present invention can efficiently and inexpensively obtain air quality information at different monitoring positions in the car by arranging a passive sampling device in the car, and can scientifically calculate and adjust the fresh air ratio according to the average value of the characteristic gas concentration and the air supply volume of the fresh air system to generate fresh air volume management measures. This method avoids the problems of high noise, insufficient space coverage and high demand for vehicle structure modification in traditional monitoring methods, and achieves the purpose of effectively reducing the energy consumption of the fresh air system while ensuring that the pollutant concentration in the car meets the standard. In addition, by setting weight coefficients to give reasonable weights to the characteristic gas concentrations at different monitoring points, the accuracy of the pollutant concentration distribution assessment is improved, and the fresh air volume management effect is further optimized. The present invention meets the air quality and energy-saving requirements under different operating conditions, and provides a scientific basis and technical support for green, healthy and low-carbon rail transit operations. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a flow chart of a method for managing fresh air volume in rail transit carriages based on passive sampling technology of the present invention;

[0023] Figure 2 This is a schematic diagram of the vertical distribution of monitoring points in the carriage;

[0024] Figure 3 This is a schematic diagram of the horizontal distribution of monitoring points in the carriage; DETAILED DESCRIPTION

[0025] In order to make the purpose, technical solutions and advantages of the present invention more clear, the present invention is described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] The characteristic gas in the present invention may be one of carbon dioxide, ammonia, total volatile organic compounds, and formaldehyde. In this embodiment, carbon dioxide is used as an example.

[0027] like Figure 1 , Figure 2 In this embodiment, a rail transit carriage fresh air volume management method based on passive sampling technology may specifically include:

[0028] A measurement car is selected in the train, and the measurement car includes the head / tail car and the middle car. In this embodiment, the measurement car selects three cars, namely cars 1, 3, and 5, as the measurement cars. Four monitoring positions are preset in the measurement car, and a passive air sampling device that can be quickly disassembled and assembled is arranged. The four monitoring positions are respectively set at a height of 1.6m near the door in the car marked as P1, a height of 1.1m in the middle of the car marked as P2, a height of 1.6m in the middle of the car marked as P3, and a height of 1.6m near the return air outlet under the car seat marked as P4. The device only collects carbon dioxide samples, and the sampling rate is about 60ml / min.

[0029] The specific locations of P1-P4 are as follows Figure 2 and Figure 3 As shown in the figure, considering that people are the main source of carbon dioxide emissions, the distribution characteristics are "the concentration in the middle of the car is higher than that at the door", and the two groups of people in the seats and standing seats are at different breathing zone heights. The position distribution of P1-P3 takes into account the horizontal distribution in the middle of the car and the door and the vertical distribution at different monitoring heights in the car. P4 represents the average concentration level of the air mixture in the car at the return air point.

[0030] After obtaining the air samples, the air information of different monitoring positions in the carriage is analyzed. The above sampling method divides the measurement into multiple time periods according to the operation time of the train.

[0031] Specifically, taking a 6-carriage operating line of Guangzhou Metro as an example, according to the real-time passenger flow and the climate characteristics of Guangzhou, the monitoring period is divided into nine periods from T1 to T9 according to working days and holidays. Table 1 gives the specific time points of each period and the corresponding division basis:

[0032] Table 1. Division of each measurement period from T1 to T9 and its basis

[0033]

[0034] The passive air sampling device was used to collect carbon dioxide air samples at each point P1-P4 in the 1st, 3rd and 5th carriages during the nine periods T1 to T9. After laboratory analysis, the concentration distribution information of carbon dioxide in the carriages during the corresponding period was obtained. Table 2 shows the final carbon dioxide concentration monitoring results, expressed in mg / m 3 count.

[0035] Table 2. CO in carriages 1, 3, and 5 at different measurement periods on a certain operating line in Guangzhou 2 Concentration monitoring results

[0036]

[0037]

[0038] Based on the actual monitoring results, we first calculate the average carbon dioxide concentration in the car during a certain measurement period. According to the principle that air monitoring should pay more attention to the concentration of pollutants at the height of the breathing zone of most people, the weight factors k corresponding to P1~P4 are 1 , k 2 , k 3 , k 4 Take 20%, 35%, 35% and 10% respectively, that is, the average concentration of carbon dioxide in carriages 1, 3 and 5 in each measurement period, Thereby obtaining the average value of characteristic gas concentration in a single measured compartment.

[0039] According to the characteristic gas concentration values ​​in multiple measured carriages, the average characteristic gas concentration of the entire train is estimated, specifically through the formula Calculate, Ti is the time period of calculation, n is the total number of train carriages, C (ω)头 is the average value of characteristic gas concentration in the head / tail compartment, C (ω)中 is the average value of characteristic gas concentration in the middle compartment. Taking T1 period as an example, The calculated results of the average carbon dioxide concentration in carriages 1, 3, 5 and the entire vehicle at each measurement period are shown in Table 3.

[0040] Table 3. CO of carriages 1, 3, 5 and the whole vehicle at each measurement period 2 Concentration average

[0041]

[0042] The fresh air ratio adjustment value is calculated based on the average value of the characteristic gas concentration of the entire train and the air supply volume of the train fresh air system. Calculate the fresh air ratio adjustment value. Among them, C s is the safety threshold of characteristic gas concentration in the car, C 0 is the characteristic gas concentration value in the train fresh air system; V 车 is the volume of the train compartment, V 送 It is the total air supply volume in the carriage during the measurement period. For example, the total air supply volume in the carriage is 9000m 3 / h; Carriage length 19m, width 2.8m, body height 3.8m, floor height 1.1m; Fresh air carbon dioxide content (C0 ) is 450ppm, about 884mg / m 3 According to the latest version of the "Indoor Air Quality Standard" GB / T18883-2022, the indoor carbon dioxide concentration limit (C S ) is 0.1%, i.e. 1000ppm, which is about 1964mg / m 3 Combined with the vehicle carbon dioxide concentration in each operating period from T1 to T9 in Table 3 The estimation results are used to calculate the actual fresh air ratio adjustment value (Δn) required for the train to depart during each measurement period. The results are shown in Table 4.

[0043] Table 4. Fresh air ratio adjustment value Δn of subway trains in each measurement period

[0044]

[0045] The calculation results of the train fresh air ratio adjustment value based on carbon dioxide concentration monitoring show:

[0046] The fresh air ratio adjustment value is negative during the period when the train passenger flow is relatively small, that is, the ratio of the fresh air volume to the total air volume in the train compartment during this period can be appropriately reduced to achieve energy saving effects. For example, the initial low peak period T1 and high temperature flat peak period T3 on weekdays, and the initial low peak period T6 and daytime flat peak period T7 on holidays.

[0047] The fresh air ratio adjustment value during the peak period is positive, that is, the pollutant concentration in the carriage exceeds the concentration limit of the hygienic standard during the corresponding period, and the fresh air ratio of the train carriage should be appropriately increased to achieve the purpose of diluting pollutants and maintaining healthy air quality in the car. For example, the morning peak T2, evening peak T4 and normal temperature flat peak T5 on weekdays, the peak T8 on holidays, and the night flat peak T9.

[0048] This method is based on the actual pollutant concentration in the carriage obtained by monitoring with an unpowered passive sampling device, and at the same time adjusts the existing fresh air volume in the train in combination with the corresponding air quality hygiene standard limit requirements. It uses a green monitoring method that is small, non-interference, has a wide time and space coverage, and does not require electricity or energy. It achieves the purpose of scientifically managing the energy consumption of the train ventilation and air-conditioning system while fully protecting the health of drivers and passengers. It is a scientific and reasonable method for managing the fresh air volume of trains.

[0049] The above description is only a preferred embodiment of the present application and an explanation of the technical principles used. Those skilled in the art should understand that the scope of the invention involved in the present application is not limited to the technical solution formed by a specific combination of the above technical features, but should also cover other technical solutions formed by any combination of the above technical features or their equivalent features without departing from the concept of the present application. For example, the above features are replaced with the technical features with similar functions disclosed in the present application (but not limited to) to form a technical solution.

Claims

1. A method for managing fresh air volume in rail transit carriages based on passive sampling technology, characterized in that: The method comprises: Select several measurement carriages in the train, arrange air passive sampling devices at preset monitoring positions in the measurement carriages, obtain air samples, and obtain air information at different monitoring positions in the measurement carriages; According to the air information obtained at different monitoring positions, the average concentration of one of the gases in the air information of a single measuring compartment is calculated to obtain the average concentration of the characteristic gas. According to the average concentration of the characteristic gas in several measuring compartments, the average concentration of the characteristic gas of the whole train is calculated. The fresh air ratio adjustment value is calculated based on the average value of the characteristic gas concentration of the entire train and the air supply volume of the train's fresh air system, and fresh air volume management measures are generated.

2. The method for managing fresh air volume in rail transit carriages based on passive sampling technology according to claim 1 is characterized in that: The measured carriages include the head / tail carriages and the middle carriages, wherein the number of carriages in the middle carriages is greater than the number of carriages in the head / tail carriages.

3. The method according to claim 2, characterized in that: A single measurement carriage includes four monitoring points, which are respectively set at a height of 1.6m near the door, 1.1m high in the middle of the carriage, 1.6m high in the middle of the carriage, and at the return air outlet under the seat, marked as P1, P2, P3, and P4 respectively.

4. According to the rail transit carriage fresh air volume management method based on passive sampling technology of claim 3, according to the air information obtained at different monitoring positions, the concentration average value of one of the gases in the air information of a single measurement carriage is calculated respectively to obtain the characteristic gas concentration average value, which is characterized in that: The weight coefficients k1, k2, k3, k4 are set for the four monitoring points P1, P2, P3, and P4 respectively, and k2=k3>k1>k4. (ω)j =k1×C P1 +k2×C P2 +k3×C P3 +k4×C P4 Calculate the average concentration of the characteristic gas in the measured compartment, where ω is the characteristic gas, j is the compartment number, C P1 , C P2 , C P3 , C P4 They are the characteristic gas concentration values ​​corresponding to the monitoring points P1, P2, P3 and P4 in the carriage respectively.

5. The method for managing fresh air volume in rail transit carriages based on passive sampling technology according to claim 4 is characterized in that: k1=0.2, k2=0.35, k3=0.35, k4=0.

1.

6. According to the method for managing fresh air volume in rail transit carriages based on passive sampling technology in claim 5, the average value of characteristic gas concentration in the whole train is calculated based on several measured average values ​​of characteristic gas concentration in the carriage, characterized in that: By formula Calculate the average value of characteristic gas concentration of the whole train, where Ti is the time period of measurement, n is the total number of train carriages, and C (ω)头 is the average value of characteristic gas concentration in the head / tail compartment, C (ω)中 It is the average value of characteristic gas concentration in the middle compartment.

7. According to the rail transit carriage fresh air volume management method based on passive sampling technology in claim 6, the fresh air ratio adjustment value is calculated according to the average value of the characteristic gas concentration of the whole train and the air supply volume of the train fresh air system, and the fresh air volume management measures are generated, characterized in that: The concentration of characteristic gases in the train fresh air system is detected to obtain the characteristic gas concentration value in the fresh air. Calculate the fresh air ratio adjustment value, where C s is the safety threshold of characteristic gas concentration in the carriage, and C0 is the characteristic gas concentration value in the fresh air of the train; V 车 is the volume of the train compartment, V 送 It is to measure the total air supply volume in the car during the period, calculate the fresh air ratio adjustment values ​​of several characteristic gases, select the fresh air ratio adjustment value with the largest value, and generate fresh air volume management measures.

8. The method for managing fresh air volume in rail transit carriages based on passive sampling technology according to claim 1 is characterized in that: The characteristic gas is one of carbon dioxide, ammonia, total volatile organic compounds, and formaldehyde.

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