Thesis "ESTUDIO EXPERIMENTAL DE LA MORFOLOGÍA DEL HOLLÍN EN UNA LLAMA DE DIFUSIÓN LAMINAR INVERSA DE ETILENO Y PROPANO, PARA DISTINTOS ÍNDICES DE OXÍGENO."
Date
2018
Authors
CORTÉS GÓMEZ, DANIELA FERNANDA
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Abstract
Las partículas de hollín son conocidas por su impacto negativo en el medio ambiente, ya que absorben laradiación solar e influyen en procesos importantes, como la formación de nubes y el derretimiento de la nievey hielo en ciertas partes del globo. Además, el hollín resulta riesgoso para la salud de las personas, siendo eltamaño y la superficie de estas partículas determinantes para causar enfermedades coronarias, asma, bronquitisy otras enfermedades respiratorias. Debido a esto, es importante estudiar y comprender los parámetros quecontrolan la formación y morfología de las partículas de hollín producidas en los procesos de combustión. Enla industria, se utilizan sistemas de combustión tales como hornos industriales y motores cohetes que puedenser estudiados mediante llamas de difusión inversa al igual que en el estudio de los procesos de formacióny oxidación del hollín. En esta investigación se estudió la morfología de agregados de hollín generados enllamas de difusión laminar inversa de etileno y propano, para la condición sobre smoke-point, para índices deoxigeno de 21 a 33 %. Se tomaron muestras de hollín mediante la técnica de muestreo termoforético en lalínea central de la llama y a partir de estas, se generaron imágenes mediante un microscopio electrónico detransmisión. Las imágenes fueron analizadas utilizando el método de mapeo de distancias euclidiana paraobtener el diámetro promedio de partícula primaria y el método de densidad óptica relativa modificado paradeterminar el número de partículas primarias dentro de un agregado. Además, se obtuvo el coeficiente deoverlapping proyectado, radio de giro del agregado, dimensión y pre-factor fractal. Encontrándose que losagregados de hollín de propano son más pequeños que los de etileno para las condiciones estudiadas. Ladimensión fractal obtenida bajo las diferentes condiciones de combustible y oxidante varía en un rango de1.18 a 2.05 mientras que el pre-factor fractal derivado varía entre 0.96 a 2.78.
Soot particles are known for their negative impact on the environment, as they absorb solar radiation andinfluence important processes, such as cloud formation and the melting of snow and ice in certain parts of theglobe. In addition, soot is a risk to the health of people, the size and surface of these particles being determinantof their cause of coronary heart disease, asthma, bronchitis and other respiratory diseases. Because of this, it isimportant to study and understand the parameters that control the formation and morphology of soot particlesproduced in combustion processes. In the industry, combustion systems such as industrial furnaces and rocketmotors are used, which can be studied by means of inverse laminar diusion flames as well as in the studyof soot formation and oxidation processes. In this research, the morphology of soot aggregates generatedin ethylene and propane inverse laminar diusion flames was studied, for above smoke-point condition andoxygen indexes from 21 to 33 %. Soot samples were taken by the thermophoretic sampling technique inthe central line of the flame and from these, images were generated by the use of a transmission electronmicroscope. The images were analyzed using the Euclidean distance mapping method in order to obtain theaverage primary particle diameter and the modified relative optical density method was used to determine thenumber of primary particles within an aggregate. In addition, the projected overlapping coecient, radius ofrotation of the aggregate, dimension and fractal prefactor were obtained. It is found that the soot aggregatesof propane flames are smaller than those of ethylene flames, for the conditions studied. The fractal dimensionobtained under the dierent fuel and oxidant conditions varies in a range of 1.18 to 2.05, while the derivedfractal prefactor varies between 0.96 to 2.78.
Soot particles are known for their negative impact on the environment, as they absorb solar radiation andinfluence important processes, such as cloud formation and the melting of snow and ice in certain parts of theglobe. In addition, soot is a risk to the health of people, the size and surface of these particles being determinantof their cause of coronary heart disease, asthma, bronchitis and other respiratory diseases. Because of this, it isimportant to study and understand the parameters that control the formation and morphology of soot particlesproduced in combustion processes. In the industry, combustion systems such as industrial furnaces and rocketmotors are used, which can be studied by means of inverse laminar diusion flames as well as in the studyof soot formation and oxidation processes. In this research, the morphology of soot aggregates generatedin ethylene and propane inverse laminar diusion flames was studied, for above smoke-point condition andoxygen indexes from 21 to 33 %. Soot samples were taken by the thermophoretic sampling technique inthe central line of the flame and from these, images were generated by the use of a transmission electronmicroscope. The images were analyzed using the Euclidean distance mapping method in order to obtain theaverage primary particle diameter and the modified relative optical density method was used to determine thenumber of primary particles within an aggregate. In addition, the projected overlapping coecient, radius ofrotation of the aggregate, dimension and fractal prefactor were obtained. It is found that the soot aggregatesof propane flames are smaller than those of ethylene flames, for the conditions studied. The fractal dimensionobtained under the dierent fuel and oxidant conditions varies in a range of 1.18 to 2.05, while the derivedfractal prefactor varies between 0.96 to 2.78.
Description
Catalogado desde la version PDF de la tesis.
Keywords
DIAMETRO PARTICULA PRIMARIA , DIMENSION FRACTAL , HOLLIN , OVERLAPPING , PREFACTOR FRACTAL , RADIO DE GIRO , TEM