Determination of the mass transfer coefficient of an odorant compound in a dynamic flow chamber

• Autor(a) principal: Freitas, Laize Nalli de
• Data de Publicação: 2023
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da Universidade Federal do Espírito Santo (riUfes)
• Texto Completo: http://repositorio.ufes.br/handle/10/17083
• topic: Engenharia Sanitária; Câmara de fluxo dinâmica; Coeficiente global de transferência de massa; Sulfeto de hidrogênio; Compostos odorantes; Espectofotometria; subject.br-rjbn

Odorous compounds are pollutants present in the air, originating from various sources. Diffuse sources, in particular, pose a challenge when it comes to quantifying their emissions. Different techniques, categorized as indirect and direct methods, have been developed to measure emissions from these sources. One commonly used device is the Dynamic Flux Chamber (DFC) developed by the United States Environmental Protection Agency (USEPA), which allows for enclosed measurements. In the context of this study, the main objective was to investigate the global mass transfer coefficient of hydrogen sulfide (H2S) within the USEPA DFC. Spectrophotometry was employed to analyze the liquid phase during laboratory experiments conducted using the DFC. The calculated mass transfer coefficient values for H2S ranged from 2.72E-06 m/s to 10.19E-06 m/s. The impact of the mass transfer coefficient was evaluated under three different flow rates (2.5 and 10 L/min), as well as the influence of the insertion of internal fans in the chamber. The results revealed that the mass transfer coefficient was significantly affected by the flow rates (p < 0.005), with higher flow rates leading to increased coefficient values. Additionally, the presence of larger ventilators, in both flow rates, also had a significant impact (p < 0.005) on the coefficient. These findings align with previous studies, supporting the hypothesis that for hydrogen sulfide, which primarily volatilizes through the liquid phase, the friction velocities at the liquid-gas interface and in the liquid phase contribute to increased pollutant emissions and, consequently, higher mass transfer coefficients. Another important variable that influenced the coefficient was temperature, with higher values in both the liquid and gaseous phases resulting in higher mass transfer coefficient values. Overall, this study contributes to a better understanding of the mass transfer process and its influencing factors, providing valuable insights for odor control and air quality management strategies.