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RISS 인기검색어
- 검색키워드
- 저자 : Belalcázar Cerón, Luis Carlos (검색결과 4 건)
- 무료
- 기관 내 무료
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CFD Modeling and Validation of Tracer Gas Dispersion to Evaluate Self-pollution in School Buses
Guevara Luna, Fredy Alejandro,Guevara Luna, Marco Andrés,Belalcázar Cerón, Luis Carlos 한국대기환경학회 2019 Asian Journal of Atmospheric Environment (AJAE) Vol.13 No.1
The exhaust gases expelled from the tailpipe during the transit of the buses are composed by different pollutants, each of them dangerous to the human health in different ways. Self-pollution has been detected as a phenomenon related with the passengers exposition to pollutants inside transport buses during their travels. The emissions from the tailpipe make their way to the cabin of the bus, exposing the passengers to toxic gases and particulate matter during the whole time of the trip they are making. The quantitative and detailed modeling of the pollutants in-cabin is important due to the sensitive nature of the children population to respiratory disease related to air pollution. This study assesses self-pollution in school buses using CFD modeling, this is achieved by simulating the dispersion of a tracer gas Sulfur Hexa-Fluoride (SF6) inside and outside the bus. Two previous studies datasets were used to validate the CFD model performance, and accuracy in its capacity to quantitatively describe the phenomenon. The CFD model developed and validated considered the turbulence through the k-epsilon realizable model. The system was considered as a multicomponent single-eulerianphase flow with the “species to transport” model. Transient formulation and energy were implemented. Mesh was optimized to polyhedral elements, reducing considerably the simulation time by 35%, and mesh size to 25%. The model was able to determine the behavior of the tailpipe emissions and the self-pollution phenomenon into the bus, showing that the highest concentrations (and therefore the maximum exposure) are located in the rear part of the bus. Validation of the CFD results with previous experimental measures and modeling results, reported in two previous studies, determined an error of 12% and 17% for the concentrations outside and inside the bus respectively, correlation coefficient (R2) values between 0.5 and 0.9 were obtained between CFD results for SF6 concentrations and validation dataset.
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Fredy Alejandro Guevara Luna,Marco Andrés Guevara Luna,Luis Carlos Belalcázar Cerón 한국대기환경학회 2020 Asian Journal of Atmospheric Environment (AJAE) Vol.14 No.2
BRT (Bus Rapid Transport) vehicles are a frequented microenvironment, it consists of exclusive lines for the transport of passengers in articulated buses. In many large cities of developing countries BRT vehicles are diesel operated buses emitting important amounts of PM2.5, a pollutant related with many health affectations. Evidence of high exposure levels have been reported onboard BRT vehicles, but detailed analysis of self-pollutions has not been developed. In this research, measurements of PM2.5 inside the BRT system of Bogota called TransMilenio were performed. Speed and location data were recorded in real-time. In-situ measurements were performed in 3 lines of the system: Av. El Dorado, Av. Caracas and Calle 80, in different seat locations inside the buses. PM2.5 concentrations above 120 μg/m3 were measured for all the cases studied. Values above the 24 h WHO (World Health Organization) recommendation were registered. Trips were determined to be between 20 to 40 minutes per passenger. A CFD (Computational Fluid Dynamics) model was implemented to simulate the exhaust emissions from the buses, 3 traffic velocities of BRT were evaluated: 20, 32 and 60 km/h. Measurements and simulation results were used to calculate the self-pollution ratios inside the vehicles. The rear of the buses was identified as the most polluted section onboard with a ratio of selfpollution about 35% average.
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Personal Exposure to PM2.5 in the Massive Transport System of Bogotá and Medellín, Colombia
Maria Paula Castillo-Camacho,Isabel Cristina Tunarrosa-Grisales,Lina María Chacón-Rivera,Marco Andrés Guevara Luna,Luis Carlos Belalcázar Cerón 한국대기환경학회 2020 Asian Journal of Atmospheric Environment (AJAE) Vol.14 No.3
Recent studies have shown that public transport users can be exposed to high levels of pollution emitted from their own vehicles and nearby sources. The purpose of this research is to determine the personal exposure of passengers to PM2.5 inside the vehicles of the massive public transport of two of the main and more populated cities of Colombia, Bogotá and Medellín. TM (TransMilenio powered by diesel) and SITVA (electric and gas natural vehicles) were the systems studied. Were evaluated the integration of new vehicles with technologies Euro V and Euro VI in the TM system, the impact of the weekend effect on personal exposure into public transport(TM and SITVA), and the possible differences between personal exposure regarding the ways of the systems(mixed lane or exclusive lane for TM and SITVA). To measure PM2.5 levels, a DustTrak monitor previously calibrated was used. This measurement campaigns lasted for more than 80 hours and a mean of 17000 data of PM2.5 concentrations were obtained for each route. The personal dose was calculated based on the recorded data. The mean PM2.5 concentrations and personal dose found in the research for TM are 167 µg/m³ and 2.3 µg/min, respectively, while, for SITVA they are 41 µg/m³ and 0.53 µg/min, respectively. Therefore, SITVA users have a 5 times lower personal exposure to PM2.5 than TM users. It was also found that due to the poor proportion of new TM vehicles during the monitoring period, the personal exposure in the old vehicles and in the new ones is similar. In the case of SITVA, it was evidenced that the mixed lane contributes to a high personal exposure to PM2.5 than the exclusive one.
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Marco Andrés Guevara Luna,Fredy Alejandro Guevara Luna,Juan Felipe Méndez Espinosa,Luis Carlos Belalcázar Cerón 한국대기환경학회 2018 Asian Journal of Atmospheric Environment (AJAE) Vol.12 No.2
Particulate matter (PM) measurements are important in air quality, public health, epidemiological studies and decision making for short and long-term policies implementation. However, only few cities in the word have advance air quality-monitoring networks able to provide reliable information of PM leaves in the ambient air, trends and extent of the pollution. In Colombia, only major cities measure PM concentrations. Available measurements from Bogota, Medellin and Bucaramanga show that PM concentration are well above World Health Organization guidelines, but up to now levels and trends of PM in other cities and regions of the country are not well known. Satellite measurements serve as an alternative approach to study air quality in regions were surface measurements are not available. The aim of this study is to perform a spatial and temporal assessment of PM in the ambient air of Colombia. We used Aerosol optical depth (AOD) retrieved by the Moderate Resolution Imaging Spectroradiometer (MODIS) satellite of NASA and surface measurements from the air quality networks of Bogota, Medellin and Bucaramanga. In a first step, we estimated the correlation between MODIS-AOD and monthly average surface measurements (2000 to 2015) from these three cities, obtaining correlation coefficient R values over 0.4 for the cities under study. After, we used AOD and PM10 measurements to study the temporal evolution of PM in different cities and regions. Finally, we used AOD measurements to identify cities and regions with the highest AOD levels in Colombia. All the methods presented in this paper may serve as an example for other countries or regions to identify and prioritize locations that require the implementation of more accurate air quality measurements.
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