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abstract: Micro/meso combustion has several advantages over regular combustion in terms of scale, efficiency, enhanced heat and mass transfer, quick startup and shutdown, fuel utilization and carbon footprint. This study aims to analyze the effect of temperature on critical sooting equivalence ratio and precursor formation in a micro-flow reactor. The effect of temperature on the critical sooting equivalence ratio of propane/air mixture at atmospheric pressure with temperatures ranging from 750-1250°C was investigated using a micro-flow reactor with a controlled temperature profile of diameter 2.3mm, equivalence ratios of 1-13 and inlet flow rates of 10 and 100sccm. The effect of inert gas dilution was studied by adding 90sccm of nitrogen to 10sccm of propane/air to make a total flow rate of 100sccm. The gas species were collected at the end of the reactor using a gas chromatograph for further analysis. Soot was indicated by visually examining the reactor before and after combustion for traces of soot particles on the inside of the reactor. At 1000-1250°C carbon deposition/soot formation was observed inside the reactor at critical sooting equivalence ratios. At 750-950°C, no soot formation was observed despite operating at much higher equivalence ratio, i.e., up to 100. Adding nitrogen resulted in an increase in the critical sooting equivalence ratio. The wall temperature profiles were obtained with the help of a K-type thermocouple, to get an idea of the difference between the wall temperature provided with the resistive heater and the wall temperature with combustion inside the reactor. The temperature profiles were very similar in the case of 10sccm but markedly different in the other two cases for all the temperatures. These results indicate a trend that is not well-known or understood for sooting flames, i.e., decreasing temperature decreases soot formation. The reactor capability to examine the effect of temperature on the critical sooting equivalence ratio at different flow rates was successfully demonstrated. / Dissertation/Thesis / Masters Thesis Aerospace Engineering 2019

Made available in DSpace on 2015-09-25T12:23:40Z (GMT). No. of bitstreams: 1 Danuza Costa Campos.pdf: 804335 bytes, checksum: 441982181b951341885ec2d7d4211a38 (MD5) Previous issue date: 2009-07-09 / By the population growth, the production of municipal solid residues is enhancing, and consequently the final disposal of such residues has been one of the major environmental problems faced in large urban centers. Lately the most used form of arrangement is the sanitary landfill, and when the residues are biodegraded inside the landfill cells they produce leachate and biogas. The leachate is a highly liquid pollutant, besides having high concentrations of ammonia nitrogen. Treating leachate is a very difficult task once its composition is very complex. A kind of treatment that is being developed is the stripping of ammonia where this chemical will be removed from the leachate by the mass transfer of the liquid phase to gas. Therefore, this paper addressed to study the ammonia stripping process in leachate liquids using plug-flow reactors in series. In order to accomplish the experimental part four plugflow reactors in series were built, with average height of 50 centimeters, without forced air supplier and without the leachate pH adjustment. The leachate samples used was from the metropolitan landfill of João Pessoa city, Paraiba, which was collected and transported to the EXTRABES laboratory and made the physicalchemical caracterization. The experimental monitoring system consisted of four distinct phases, with applied superficial loads of 450, 500, 600 and 700 kg NH4 +. ha 1.dia 1, hydraulic detention time equal to 65, 60, 50 and 38 days, and it was obtained an average efficiency of ammonia nitrogen removal around 96.1%, 99.7%, 99.5% and 98.5% respectively. At the end of monitoring, the reactor was discharged and made microscopic examinations of the remaining sludge reactor and each can observe the presence of bacteria fototróficas anoxigênicas, cocci, bacilli and algae. Can be found in this study that the higher the applied superficial load, was greater efficiency of removal of ammonia nitrogen, which may be load tested to verify the larger surface of contaminant removal. / Com o aumento populacional, a geração de resíduos sólidos urbanos vem aumentando, e com isso a disposição final desses resíduos vem sendo um dos graves problemas ambientais enfrentados nos grandes centros urbanos. A forma de disposição mais utilizada ultimamente é o aterro sanitário, e quando os resíduos são biodegradados dentro das células dos aterros, esses geram lixiviado e biogás. O lixiviado é um líquido altamente poluidor, haja vista, possuir altas concentrações de nitrogênio amoniacal. Tratar lixiviado é uma tarefa muito difícil devido a sua composição ser muito complexa. Um tratamento que vem sendo desenvolvido é o stripping de amônia, no qual a amônia vai ser removida do lixiviado por transferência de massa da fase líquida para a fase gasosa. Com isso, o presente trabalho tem como objetivo estudar o processo de stripping de amônia em líquidos lixiviados, utilizando reatores em série de fluxo pistonado. Para a realização da parte experimental foram construídos quatro reatores em série de fluxo pistonados, com altura média de 50 centímetros, sem alimentação forçada de ar e sem correção do pH do lixiviado. O lixiviado utilizado foi proveniente do aterro metropolitano de João Pessoa, onde foi coletado e transportado até as dependências físicas do laboratório da Estação Experimental de Tratamento Biológico de Esgoto Sanitário EXTRABES e feito a caracterização físico-química. O monitoramento do sistema experimental constou de quatro fases distintas, com cargas superficiais aplicadas de 450, 500, 600 e 700 kg NH4 +.ha 1.dia 1, tempo de detenção hidráulica igual a 65, 60, 50 e 38 dias, e obteve-se uma eficiência média de remoção de nitrogênio amoniacal em torno de 96,1%, 99,7%, 99,5% e 98,5%, respectivamente. Ao final do monitoramento, os reatores foram descarregados e feitos exames microscópicos no lodo remanescente de cada reator e pode-se observar a presença de bactérias fototróficas anoxigênicas, cocos, bacilos e algas. Pode ser constatado nesta pesquisa que quanto maior a carga superficial aplicada aos reatores, maior foi eficiência de remoção de nitrogênio amoniacal, podendo ainda ser testadas cargas superficiais maiores para verificar a remoção desse contaminante.