Eficiência em processos de combustão: novos métodos de análise na formação de fuligem

Abstract

Neste trabalho, avaliou-se a eficiˆencia no processo de combust˜ao controlada e enrique cida com oxigˆenio, nas propor¸c˜oes 21%, 23% e 25%, usando dois combust´ıveis Acetileno (AC) e G´as Natural (GN) nos padr˜oes espa¸cos-temporais e auto afinidade gerada por uma evolu¸c˜ao do sistema. Usou-se dois m´etodos de an´alises na eficiˆencia durante o processo de combust˜ao, o primeiro ´e a distˆancia de Hamming (Hd), t´ecnica usada para avaliar a evolu¸c˜ao dinˆamica de um sistema e o segundo m´etodo ´e conhecido por Detrended Fluc tuation Analysis (DFA), cuja s´erie temporal avalia a auto afinidade e correla¸c˜ao de longo alcance. Para o combust´ıvel AC na concentra¸c˜ao de 21% de oxigˆenio, a Hd mostrou-se ini cialmente um estado transiente, denotando que esse processo de combust˜ao se comporta como um autˆomato de Wolfram, indicando assim um aumento significativo na oxida¸c˜ao da chama e forma¸c˜ao de fuligem. Na an´alise do DFA verificou-se um comportamento auto afim bem definido para os dois gases. Constatou-se que comportamentos sub-difusivos podem estar associados a um regime turbulento e ineficiente. ABSTRACT: The present work refers to an experimental study of the efficiency applied at the combus tion processs. Where were evaluated the thermal radiation from two fuels, natural gas (NG) and acetylene (AC) enriched with oxygen at 21%, 23% and 25%, during a combus tion process. For purpose of study the efficiency during the combustion process, it was used two methods. The first is the hamming distance (HD), this technique is used to evaluate the dynamic evolution of a system. The second one is Detrended Fluctuation Analysis (DFA), method that is able to characterize long-term correlations in time series and self affinity properties. In this work, it was found for the AC fuel at the concentration of 21% oxygen, the HD shows a transient state, that indicates that its behavior works as an automaton Wolfram, thus indicating a significant increase in the oxidizing flame and soot formation. In case of the DFA method, the study showed that sub-diffusive behavior could be associated with a turbulent and inefficient regime. Finally, the results suggest that these methods can be used as an interesting tool to obtain the behavior in a combustion process.