Subway Cabin Research Articles

Mechanical Ventilation Strategy for Subway Cabins Using Numerical Simulations

Seoul metropolitan subway network is known to be the one of the most heavily used transportation means in the world. The subway cabins are naturally ventilated when the cabin doors are opened and through the gaps caused by the incomplete air-tightening of cabin bodies. Although, subway trains are equipped with a mechanical exhaust fan, the apparatus is rarely operated due to the problem of heating/cooling efficiency especially in the summer and winter seasons. In this study, we analyzed the transient CO2 (carbon dioxide) concentration level during the journey of a subway cabin when a heavy load of passengers of up to 200% of designed capacity using a CFD (computational fluid dynamics) analysis. With an increased journey time, the CO2 concentration increased by up to 5,000 ppm depending on passenger load. Through the operation of a mechanical exhaust fan, the high concentration of CO2 decreased down to 1,500 ppm. The effect of the exhaust fan operating on the dilution of indoor air was estimated by comparison with a closed cabin. In addition, the energy consumption for cooling in summer time was assessed for exhaust fan operations.

Source identification of PM10 pollution in subway passenger cabins using positive matrix factorization

Monitoring the air quality in subway passenger cabins is important because of the large number of passengers and potentially high levels of air pollution. This report characterized PM 10 levels in subway cabins in Seoul, Korea, and identified PM 10 sources using elemental analysis and receptor modeling. PM 10 levels in subway cabins were continuously measured using a light scattering monitor during rush and non-rush hours. A total of 41 measurements were taken during rush and non-rush hours, and the measurements were repeated in all four seasons. Filter samples were also collected for elemental composition analysis. Major PM 10 sources were identified using positive matrix factorization (PMF). The in-cabin PM 10 concentrations were the highest in the winter at 152.8 μg m −3 during rush hours and 90.2 μg m −3 during non-rush hours. While PM 10 levels were higher during rush hours than during non-rush hours in three seasons (excluding summer), these levels were not associated with number of passenger. Elemental analysis showed that the PM 10 was composed of 52.5% inorganic elements, 10.2% anions, and 37.3% other. Fe was the most abundant element and significantly correlated ( p < 0.01) with Mn ( r = 0.97), Ti ( r = 0.91), Cr ( r = 0.88), Ni ( r = 0.89), and Cu ( r = 0.88). Fe, Mn, Cr, and Cu are indicators of railroad-related PM 10 sources. The PM 10 sources characterized by PMF were soil and road dust sources (27.2%), railroad-related sources (47.6%), secondary nitrate sources (16.2%), and a chlorine factor mixed with a secondary sulfate source (9.1%). Overall, railroad-related sources contributed the most PM 10 to subway cabin air. ► PM 10 levels in subway cabins were highest during the winter. ► The in-cabin PM 10 levels were not associated with passenger number. ► Elemental analysis of PM 10 showed that Fe was the most abundant element. ► Four PM 10 sources in cabins were identified by positive matrix factorization. ► Railroad-related sources contributed the most PM 10 to subway cabin air.

지하철 전동차 객실에서의 PM10오염특성 파악에 관한 연구

This study had the aim of characteristics of <TEX>$PM_{10}$</TEX> in subway cabins. <TEX>$PM_{10}$</TEX> was measured by times of day (rush and non rush hours) and seasons with real time <TEX>$PM_{10}$</TEX> sampler on the subway cabins of line 7. Filter samples were collected for evaluation of their elemental composition as well as identification of major sources of <TEX>$PM_{10}$</TEX> using a receptor model, PMF. <TEX>$PM_{10}$</TEX> concentration were the highest in the winter season both in the rush and non rush hours at 152.8 <TEX>${\mu}g/m^3$</TEX>, 90.2 <TEX>${\mu}g/m^3$</TEX> respectively. The <TEX>$PM_{10}$</TEX> concentrations in rush hour were 30% higher compared to non rush hours. Based on the chemical information, the composition rare of inorganic elements was 52.5%, anions were 10.2% and others were 37.3%. Fe was the most abundant element and significantly correlated (p.0.01) with Mn (r=0.97), Ti (r=0.91), Cr (r=0.88), Ni (r=0.89) and Cu (r=0.88). Characterized <TEX>$PM_{10}$</TEX> sources by PMF in the cabin were soil and road dust related sources (27.2%), railroad related sources (47.5%), secondary nitrate sources (16.2%) and a Cl-factor mixed with a secondary sulfate source (9.1%).

도시철도 객실 공기질 개선을 위한 롤필터 개발연구

현대사회는 많은 교통수단이 이용되고 있으며, 그 중 수도권 도시철도는 하루 평균 721만명이 사용하는 중요한 교통수단이다. 실내공기질에 대한 관심과 PSD의 설치로 인해 터널내공기질 문제에서 객실내 공기질로 이동하고 있다. 하지만 현재 객실내 공기질 향상을 위한 장치는 전무한 상태이며 기존 에어필터 기술 적용시 설치비용과 유지보수가 문제점으로 지적되고 있다. 연구의 최종목표는 미세먼지와 이산화탄소를 효과적으로 저감시킬수 있는 독립형 청정장치를 개발하는 것이고, 본 연구에서는 미세먼지 저감기능을 수행하는 롤필터 집진 장치개발을 목적으로 한다. 객실내 롤필터 집진장치를 설치할 수 있는 공간에 대해 조사하고, 이에 따른 도시철도 객실 먼지저감에 효과적인 시스템 구조를 제시하였으며, 적정 풍량을 산정하다. 유동해석과 먼지저감효율에 대한 수치해석적 연구를 통해 최적운영 조건을 분석하였다. 그리고 롤필터에 적용가능한 필터재질에 대하여 차압특성과 입자포집효율을 평가하여 객실 유닛에 가장 적합한 필터를 선정하였다. In a modern society, various type of transportation modes are utilized, among them the subway system is the one of the main transportation mode which more than 7.21 million people ride a day in Seoul. Due to the increased interests on the indoor air quality (IAQ) of underground facilities, public concerns on IAQ of subway system are increasing also. Platform screen door (PSD) recently installed at the whole stations of Seoul subway and tunnel washing-out appeared to be effective in reducing particulate matters in the platform and tunnel. However there has not been any attempt to improve IAQ of subway cabin inside. Most technologies for removing airborne particulate matters are known to be difficult to adopt on the subway cabin due to the problem of maintenance cost. Therefore, the object of this study is a practical development of cabin air cleaning system which can reduce the concentration of airborne particles and harmful gases at the same time. In this paper, we focused on the development of particle removing system utilizing a roll-filter for increasing operating time of air filter. The prototype of system was designed and manufactured based on the numerical prediction results. For rollfilter device, 5 candidate filter materials were tested in point of particle collection efficiency and pressure drop. It was found that the electrically charged filter material showed the highest performance among them.

수도권 전동차에서의 공기질 현황 및 다변량 통계분석을 이용한 공기질 영향인자 분석

In this study, we have observed PM-10 and concentration in the subway cabins and analyzed the factors affecting air quality using a multivariate statistical analysis. The measurements have been conducted at Seoul metropolitan subway lines. The results show that the mean concentration of the PM-10 and inside subway cabins is in the range of 62.6 to 108.0 and 907 to 2,008 ppm, respectively. level in specific sections during the rush hours has exceeded air quality guidelines for public transportation, which requires designated train ventilation controls. Correlation and regression analyses of influencing factors imply that level is severely influenced by the number of passengers and PM-10 level is also correlated with the number of passengers. In particular, PM-10 level in the cabins indicates a positive correlation with outdoor PM-10 level. In addition, the PM concentration has been highly affected by the number of passengers and distance between stations.

제올라이트계 이산화탄소 흡착제를 사용한 지하철 객실 내부의 이산화탄소 제거에 관한 연구

지하철 객실은 고농도의 이산화탄소로 오염되기 쉬운데, 이로 인하여 지하철 승객의 졸림, 두통, 무력감 등을 야기하기 쉽다. 이 때문에 환경부에서는 2007년에서는 열차와 지하철 객실의 이산화탄소 농도에 대한 가이드라인을 정한 바 있다. 본 연구에서는 지하철 객차용 이산화탄소 저감 시스템을 개발하고 실험용 객차를 이용하여 성능시험을 수행하였다. 다양한 종류의 개질 제올라이트를 이산화탄소 흡착제로 사용하여 지하철 객실 내부의 이산화탄소 농도를 저감할 수 있었다. High concentration of carbon dioxide at subway cabin is one of the serious environmental concerns because carbon dioxide causes drowsiness, headache, and nervelessness of passengers. Ministry of Environment set a guideline for indoor carbon dioxide levels in train or subway in 2007. In this study, a carbon dioxide removal system for subway cabin was developed and tested using a test subway cabin. Various types of modified zeolites were used as the adsorbent of carbon dioxide. The tested zeolites were applied to the subway cabin, and showed high potential to lower the indoor <TEX>$CO_2$</TEX> level.