Exploratory studies on the applicability of spectral sensors for the measurement of fuel/air ratio in hydrogen-enriched flames

• Autor(a) principal: Peixoto, João Paulo Nunes
• Data de Publicação: 2022
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10773/38542
• topic: Flame spectroscopy; Flame chemiluminescence; Equivalence ratio determination; Hydrogen-enriched gas

The aim of this work was to study the applicability of spectral sensors for the detection of the fuel/air ratio in hydrogen-rich ames. For this, an experimental apparatus was built, capable of producing premixed ames, and an acquisition system, capable of detecting the emission spectra of these ames. This study is based on the fact that ame properties have a strong correlation with the fuel/air ratio, or equivalence ratio, and the need to accurately determine this ratio is a prerequisite for optimizing combustion and limiting the emission of pollutants. Consequently, several tests were carried out in order to determine for which equivalence ratios the ame was stable, and the pro le of the ame was also studied to determine which would be the best zone to detect chemiluminescence signals. The experimental results revealed that the CH*/OH* ratio is the most stable, but it does not seem to be the most suitable for monitoring the equivalence ratio, especially for mixtures with a high percentage of hydrogen. In fact, none of the species' ratios studied make it possible to obtain the equivalence ratio by itself and unequivocally. To overcome this problem, a strategy is presented that involves the use of information from several sensors, which together allow us to infer the equivalence ratio in the studied ranges for the different fuel mixtures used.