Papers by Marco Guevara Luna
Modeling Earth Systems and Environment
Bus rapid transit (BRT) vehicles are common microenvironments in urban areas. In some cities, the... more Bus rapid transit (BRT) vehicles are common microenvironments in urban areas. In some cities, these BRT vehicles are diesel-powered, which makes them highly pollutant. Recent studies report high levels and exposure risk to particulate matter in BRT vehicles. Nevertheless, extensive research has yet to be published, including gaseous pollutants (e.g., CO). Nevertheless, extensive research including gaseous pollutants (e.g., CO) has not been published. This research aims to evaluate the self-pollution of BRT buses in terms of exhaust gasses. For this, measurements and computational fluid dynamics (CFD) were used. Results suggest that pollutant concentrations stay low during most of the trips. However, some areas of the buses have significant swings and peaks due to the transit cycle. Here, we used CFD modeling to evaluate the dispersion of the exhaust CO inside and outside the bus. CFD results show that the bus rear has the highest concentrations, with a mean self-pollution ratio of 1...
Servicios ecosistémicos: Un enfoque introductorio con experiencias del occidente Colombiano
Servicios ecosistémicos: Un enfoque introductorio con experiencias del occidente Colombiano, 2019
La relación que existe entre las variables meteorológicas y la calidad del aire ha sido estudiada... more La relación que existe entre las variables meteorológicas y la calidad del aire ha sido estudiada históricamente en todo el mundo. Esfuerzos por comprender la relación que existe entre estas, y como se interrelacionan para reproducir escenarios futuros y así mitigar impactos, son el objeto del estudio moderno de las ciencias ambientales aplicadas al aire como recurso vital (González et al., 2018). Todo esto centrado en describir cuantitativamente, y con precisión, la afectación del clima, frente a un momento actual cercano al punto de no retorno en términos de variabilidad y cambio climático.
Revista Facultad de Ingeniería Universidad de Antioquia, 2019
In Colombia, hydropower share was 70 % of the total installed capacity and more than 50 % of the ... more In Colombia, hydropower share was 70 % of the total installed capacity and more than 50 % of the monthly generation share in 2015, which coincided with the strongest El Niño Southern Oscillation (ENSO) phenomenon reported in the region. ENSO has been recognized as an influential climate pattern on meteorological variables. The generation via hydropower implies the construction of dams and water reservoirs; these flooded areas generate an important amount of Green House Gases (GHG). In this regard, the main aim of this research was to quantify the diffusing emissions of CO2 and CH4 in the flooded areas of the main hydroelectric power generation facilities in Colombia. GHG emissions were calculated by the implementation of an IPCC methodology. The obtained results show that more than 1,042,500 t CO2-Eq (i.e. CO2 and CH4) are emitted in Colombia per year from this source, representing 4.4 % of the total GHG emissions in the country. As the second aim, the vulnerability of Colombia’s en...
Revista de Investigación Agraria y Ambiental, 2018
Noise pollution as byproduct of development and urban activity is related with a great amount of ... more Noise pollution as byproduct of development and urban activity is related with a great amount of economical, social and cultural variables, whose importance as stressing, and possible even dangerous agent in human life has come to be recognized in the last decades. In this case the megacity of Bogotá is the capital of Colombia, located in the center of the country. Bogotá is a very variable city in terms of economical and social level location, and even use of soils in the city planning. The factors mentioned above makes Bogotá a very complex analysis system for sound and noise pollution studies. Due to the size of the city, in this study the western area of the capital district was analyzed through sound measurements in 7 sites selected by types of areas, involving commercial, transportation, industrial, residential and arterial roads. The main objective of this study was to identify the most important noise sources in the western area of the city. This study allowed to identify the arterial roads as one important source of noise in the city, possibly due to the traffic or heavy vehicles inside the city. The maximum harmful levels of sound reach values of about 85 dB in the mentioned locations (Ciudad de Cali avenue, Cll 13 avenue arterial roads and Salitre-El Greco Transmilenio Station), exceeding the permitted limits of 75 dB(A) according to the local environmental standards.
CT&F - Ciencia, Tecnología y Futuro, 2018
Micro-diverter valves are innovative and efficient devices used to generate microbubbles that can... more Micro-diverter valves are innovative and efficient devices used to generate microbubbles that can significantly enhance process efficiency in industry. Micro-diverter valves have been experimentally tested and modeled using CFD in previous works. However, a detailed CFD modeling evaluation of these valves has not been performed employing detailed turbulence modeling at transient and steady state. This article presents a three-dimensional CFD simulation and performance evaluation of a bi-stable diverted valve for microbubble generation. In the model, transient and steady state approaches were used to quantify the behavior in the valve. The κ – ε standard and κ – ε RNG turbulence models were used and compared. Different mesh configurations, mesh generation methods, and both turbulence models were evaluated to find the best set-up to simulate this valve. A brief analysis of the time-step size using the Courant number approach was also performed. Operation conditions at low Reynolds (38...
Environmental Science and Pollution Research, 2021
The TransMilenio (TM) is a transport system. Twenty-year-old TM is a fast, highly efficient, and ... more The TransMilenio (TM) is a transport system. Twenty-year-old TM is a fast, highly efficient, and self-sufficient mode of passenger transport. This work aims to evaluate the effects of changing current TM diesel buses by electricity-powered buses (battery, wire-based), on the PM2.5 concentrations at surface level. Emissions calculations considering combustions and resuspension of TM and Non-TM were performed. A CFD model was implemented to estimate current PM2.5 concentrations at the roadside level, and the CFD results were validated using the statistic parameters: MB, RMSE, r, and IOA. Results from the emission calculations indicate that TM buses (30–50%) are one of the main sources of primary PM2.5 in all the considered urban sites in this study. Non-exhaust emissions from most vehicle categories were also identified as an important source of primary PM2.5 (40% of total emissions). The CFD model reproduced closely the trends and levels of PM2.5 concentrations measured at the roadside level in all the locations. Replacing TM diesel vehicles with electric vehicles reduces PM2.5 concentrations between 10 and 30% according to the CFD results obtained. Higher reductions can be achieved if policies are adopted to control other types of vehicles and non-exhaust emissions since they have a contribution of about 60%. Finally, this study shows that the combined use of emission calculations and advanced near-road dispersion models are useful tools to study and manage air quality in large cities.
2019 Congreso Colombiano y Conferencia Internacional de Calidad de Aire y Salud Pública (CASP)
BRT (Bus Rapid Transit) public transport systems, are highly frequented micro environments by the... more BRT (Bus Rapid Transit) public transport systems, are highly frequented micro environments by the population of a city. In this research a TSI DustTrak II was used to determine the PM2.5 concentration inside the buses of the BRT system in Bogotá, and a GPS app, MyCarTracks®, to record the speed and location data. Measurements were performed in three different segments of the system, and in different seats inside the buses. PM2.5 concentration levels above 120 µg/m3 were measured for all the segments. Time travels of the BRT passengers was determined to be around 20 to 40 minutes average, where they are exposed directly to these high levels of pollution. Thereafter, a CFD model was implemented to simulate and assess the behavior of the tailpipe emissions. Contours of concentration showed the self-pollution phenomenon as a fraction around 18% of the total concentration of PM2.5 measured inside the cabin of the BRT.
La modelación de la dispersión de contaminantes es una herramienta indicativa que aporta en la ge... more La modelación de la dispersión de contaminantes es una herramienta indicativa que aporta en la gestión y planificación del territorio, en la realización de estudios de impacto ambiental y en los planes de manejo ambiental. Información relevante: para simular y/o entender la dispersión de las emisiones de contaminantes atmosféricos provenientes de fuentes fijas se han establecido diferentes modelos atmosféricos: caja, modelo gaussiano, euleriano, lagrangiano, tipo “puff”, receptor y hasta estadísticos. En el caso de los modelos gaussianos se busca describir la dispersión en la horizontal y en la vertical con una distribución normal o de gauss que depende de los coeficientes de dispersión (variantes respecto a la estabilidad atmosférica). El modelo gaussiano se divide en tipo screening (simple) y complejo/refinado dependiendo de la cantidad y complejidad de variables y enfoque. Propósito de la nota de campus: el presente documento se constituye como una guía rápida para el entendimien...
Revista Cubana de Meteorología, 2021
Congreso Colombiano y Conferencia Internacional de Calidad del Aire y Salud Pública, Jun 17, 2019
La estimación de los niveles de material particulado PM10 y PM2.5 es parte importante de la evalu... more La estimación de los niveles de material particulado PM10 y PM2.5 es parte importante de la evaluación de la calidad del aire. En zonas en las que no se tiene monitoreo de calidad del aire en superficie, el uso de datos satelitales y reanálisis es una alternativa viable y de bajo costo aplicable en cualquier lugar del mundo. El paquete de datos “Copernicus Atmosphere Monitoring Service” (CAMS) cubre todo el globo con una resolución espacial de 0.1° (11 km), una resolución temporal de 1 hora y reporta información de la composición atmosférica y los procesos que tienen lugar en la misma, en tiempo real y predicciones de 4 días en el futuro para muchos contaminantes. Estas características hacen de CAMS un paquete de datos con posibilidad de ser aplicado para analizar la calidad del aire en países en vía de desarrollo. Por otra parte, la profundidad óptica de aerosol (AOD) de 550 nm tomada de los satélites “Moderate Resolution Imaging Spectroraiometer” (MODIS) de la NASA, tiene una resolución espacial de 1° (111 km), resolución temporal de 1 hora, sujeta a disponibilidad de datos por trayectorias polares de los satélites Terra-Aqua, y nubosidad. AOD de MODIS es una variable que ha sido utilizada en estudios previos para predecir niveles de PM10 en Colombia. El objetivo de este estudio es evaluar la calidad del aire en Colombia para PM2.5 y PM10 utilizando los datos de CAMS y MODIS durante el periodo de tiempo de 2003 a 2015. En este estudio se comparan los datos de MODIS y CAMS con datos obtenidos de las redes de monitoreo de calidad del aire de 3 ciudades de Colombia: Bogotá, Bucaramanga y Medellín. Se evaluaron los coeficientes de correlación (R) y el índice de correspondencia (IA) con el fin de evaluar el desempeño de los dos paquetes de datos (MODIS y CAMS). El análisis indica que hay una correlación estadisticamente significativa entre MODIS, CAMS y mediciones en superficie. Estos paquetes de datos pueden ser usados para analizar la calidad del aire en Colombia y en otros paises en via de desarrollo
2019 Congreso Colombiano y Conferencia Internacional de Calidad de Aire y Salud Pública (CASP), 2019
Estimation of particulate matter levels PM10 and PM2.5 is an important part of the quality assess... more Estimation of particulate matter levels PM10 and PM2.5 is an important part of the quality assessment of the air. In areas where there is no air quality monitoring surface, the use of satellite data, predictions and reanalysis are a viable and low-cost alternative applicable in any Place of the world. The data package “Copernicus Atmosphere Monitoring Service ”(CAMS) covers the entire globe with a spatial resolution of 0.1 ° (12.5 km), a temporal resolution of up to 1 hour and reports atmospheric composition information and the processes that take place in it, in real time and 4-day future predictions for various pollutants and meteorological variables. These features make CAMS a data package with the possibility of being applied to analyze the air quality in developing countries. On the other hand, Aerosol Optical Depth (AOD) of 550 nm taken from the satellites "Moderate Resolution Imaging Spectroradiometer" (MODIS) of NASA (National Aero Space Administration), has a spatial resolution of 1 ° (111 km), temporal resolution of up to 1 hour, subject to availability of data by trajectories poles from the Terra-Aqua satellites, and cloud cover at the study. MODIS AOD is a variable that has been used in previous studies to predict PM10 levels in Colombia. The objective of this study is to evaluate air quality in Colombia for PM2.5 and PM10 using CAMS data during the period of time from 2003 to 2015. correlation coefficients (R) in order to evaluate performance of the two data packages (MODIS and CAMS). Analysis indicates that there is a statistically significant correlation between MODIS, CAMS and surface measurements, as well as a CAMS ability to represent quality phenomena of the air in Colombia. These data packets can be used to analyze air quality in Colombia and other countries in the process of developing.
2019 Congreso Colombiano y Conferencia Internacional de Calidad de Aire y Salud Pública (CASP), 2019
La modelación de los fenómenos meteorológicos es un paso determinante para el desarrollo de cualq... more La modelación de los fenómenos meteorológicos es un paso determinante para el desarrollo de cualquier modelación de calidad del aire. En dominios que involucran geografía compleja la representación de la dinámica atmosférica es uno de los principales desafíos para la modelación de la calidad del aire. En Colombia múltiples estudios previos de modelación de la calidad del aire han sido desarrollados utilizando la meteorología del modelo “Weather Research and Forecast” (WRF), principalmente sobre la ciudad de Bogotá. Estos estudios han utilizado diferentes configuraciones para la representación de la meteorología. El objetivo de este estudio es implementar el modelo WRF V3.9.1 para simular la meteorología en la ciudad de Bogotá. El enfoque de este estudio se basa en el uso de una nueva topografía en Colombia, ALOS-PALSAR (12.5 m) y su comparación con la topografía estándar de WRF GEO-TOPO (1000 m) buscando reproducir con precisión el comportamiento de las variables meteorológicas que afectan la dispersión de contaminantes y química atmosférica con precisión, y compararlo con modelos de estudios previos para las ciudades de Bogotá, Manizales y ciudades de otras partes del mundo.
Environment International, 2021
This global study, which has been coordinated by the World Meteorological Organization Global Atm... more This global study, which has been coordinated by the World Meteorological Organization Global Atmospheric Watch (WMO/GAW) programme, aims to understand the behaviour of key air pollutant species during the COVID-19 pandemic period of exceptionally low emissions across the globe. We investigated the effects of the differences in both emissions and regional and local meteorology in 2020 compared with the period 2015-2019. By adopting a globally consistent approach, this comprehensive observational analysis focuses on changes in air quality in and around cities across the globe for the following air pollutants PM 2.5 , PM 10 , PMC (coarse fraction of PM), NO 2 , SO 2 , NOx, CO, O 3 and the total gaseous oxidant (OX = NO 2 + O 3) during the pre-lockdown, partial lockdown, full lockdown and two relaxation periods spanning from January to September 2020. The analysis is based on in situ ground-based air quality observations at over 540 traffic, background and rural stations, from 63 cities and covering 25 countries over seven geographical regions of the world. Anomalies in the air pollutant concentrations (increases or decreases during 2020 periods compared to equivalent 2015-2019 periods) were calculated and the possible effects of meteorological conditions were analysed by computing anomalies from ERA5 reanalyses and local observations for these periods. We observed a positive correlation between the reductions in NO 2 and NOx concentrations and peoples' mobility for most cities. A correlation between PMC and mobility changes was also seen for some Asian and South American cities. A clear signal was not observed for other pollutants, suggesting that sources besides vehicular emissions also substantially contributed to the change in air quality. As a global and regional overview of the changes in ambient concentrations of key air quality species, we observed decreases of up to about 70% in mean NO 2 and between 30% and 40% in mean PM 2.5 concentrations over 2020 full lockdown compared to the same period in 2015-2019. However, PM 2.5 exhibited complex signals, even within the same region, with increases in some Spanish cities, attributed mainly to the long-range transport of African dust and/or biomass burning (corroborated with the analysis of NO 2 /CO ratio). Some Chinese cities showed similar increases in PM 2.5 during the lockdown periods, but in this case, it was likely due to secondary PM formation. Changes in O 3 concentrations were highly heterogeneous, with no overall change or small increases (as in the case of Europe), and positive anomalies of 25% and 30% in East Asia and South America, respectively, with Colombia showing the largest positive anomaly of ~70%. The SO 2 anomalies were negative for 2020 compared to 2015-2019 (between ~25 to 60%) for all regions. For CO, negative anomalies were observed R.S. Sokhi et al.
Asian Journal of Atmospheric Environment, 2020
Asian Journal of Atmospheric Environment, 2020
Revista Facultad de Ingeniería Universidad de Antioquia, Apr 22, 2019
TECCIENCIA, 2018
Ethanol is currently one of the most important and attractive sources of energy with a heating va... more Ethanol is currently one of the most important and attractive sources of energy with a heating value of 12800 kJ/kg. Ethanol is commonly obtained from many sources worldwide, mainly renewable sources, and its separation is achieved typically by atmospheric distillation. Even so, there is new technologies looking for cheaper and more efficient ethanol separation and purification: pressure-swing distillation, extractive distillation, adsorption with molecular sieves and vacuum membrane distillation. The design, rating and optimization of these process technologies requires a reliable and universal thermodynamic modeling approach capable of represents the ethanol-water system properties, and in particular the vapor-liquid equilibrium (VLE) near the azeotropic point. This study summarize VLE experimental data for ethanol-water system at 3 vacuum pressures (13.15, 19.71 and 101.32 kPa), and 17 azeotropic point data. Thermodynamic consistency test of the data was performed using the Redlich-Kister method. The parameters and constants for the detailed thermodynamic modeling of the ethanol-water system using polar fluid Soave-Redlich-Kwong equation of state (polar-SRK) are summarized as part of this study, as well as the standard binary interaction parameters for NRTL and UNIQUAC excess Gibbs energy models. Both models are used simultaneously for the simulations involved in the chemical process engineering activities in science, academy and industry. The main target of this study consist in the regression of new binary interaction parameters in a temperature dependent form compatible with the most process simulation software, for NRTL and UNIQUAC, and its validation using experimental data for azeotropic points at 3 different low pressures with errors of less than 1%, for temperature and ethanol molar fraction in the vapor phase. The regressed new parameters were tested using isobaric experimental data for VLE at the 3 under-atmospheric pressures mentioned, obtaining correlation coefficient (R 2) values of about 1. The calculations were performed using Python 3.4® codes developed and supplied by S&S and Aspen properties® V8.6 provided by the Universidad Nacional de Colombia.
Asian Journal of Atmospheric Environment, 2019
The exhaust gases expelled from the tailpipe during the transit of the buses are composed by diff... more 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 HexaFluoride (SF 6) 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-epsi-lon realizable model. The system was considered as a multicomponent single-eulerian-phase 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 (R 2) values between 0.5 and 0.9 were obtained between CFD results for SF 6 concentrations and validation dataset.
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Papers by Marco Guevara Luna