Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Study of Flame Propagation Velocity Inside a Closed Duct and Validation with Flame Propagation Theory
Submission Author:
Marcos Dall Agnol , RS
Co-Authors:
Marcos Dall Agnol, Rafael Quines, Manuel Nzinga, Andrés Armando Mendiburu Zevallos
Presenter: Marcos Dall Agnol
doi://10.26678/ABCM.ENCIT2022.CIT22-0154
Abstract
Hydrogen is a promising renewable fuel for the future as it stands with a great energy potential and the advantage of not resulting in any type of burning pollution as its only product is water. Understanding how hydrogen behaves is relevant and should lead to new technologies that can operate this energy source. In the present work, experiments were performed by variating the Numbers of Zeldovich and Lewis using different fractions of Natural Gas, Hydrogen, and Helium. To be precise, pure Natural Gas mixed with air, 75% natural gas and 25% hydrogen with air, 50% natural gas and 50% hydrogen with air, and natural gas with air diluted in a fraction of 10% of helium. Some parameters were predetermined, for example, the equivalence ratio was taken as stoichiometric (ER = 1), and the initial pressure was set at 40kPa. These experiments took place at the Combustion Laboratory of the Federal University of Rio Grande do Sul in a duct of 105 cm in length, and cross section of 10cm x 10cm. This duct was built in Inox steel, and the experiments were carried out with the duct free of obstacles. The flame propagation was registered using a 12000-fps camera which allowed to determine the flame speed. One of the theoretical models used was to determine the mixture’s maximum speed and the distance where the flame starts to deaccelerate. The experimental results show that the flame accelerates in the earlier stages of the propagation process, and it starts to decelerate after it has travelled a determined distance. Furthermore, although the flame acceleration is clearly observable at first, the process becomes more oscillatory as the flame advances along the duct. The analytic model developed by Valiev et al was used to obtain the theoretical flame velocity, which was compared to the experimental data.
Keywords
Deflagration, Hydrogen, Flame, laminar flame, Turbulent Flame, Premixed turbulent flames, Lewis number, Zeldovich number
