Eventos Anais de eventos
ENCIT 2022
19th Brazilian Congress of Thermal Sciences and Engineering
Numerical investigation of Fe2O3-Al Thermite reaction using zero and first-order kinetic models.
Submission Author:
Fabrício Pena , SP , Brazil
Co-Authors:
Fabrício Pena, Marcelo De Lemos
Presenter: Fabrício Pena
doi://10.26678/ABCM.ENCIT2022.CIT22-0250
Abstract
The thermite reaction is a self-sustained exothermic reaction capable of producing high temperatures. Due to these features, this reaction has been employed in welding processes of railway tracks, material synthesis, pyrotechnics, ignition systems, etc. In this sense, this work proposes a numerical model to investigate the combustion behavior of a hematite/aluminum thermite reaction with two zero and first-order kinetic models. As such, a constant kinetic rate is adopted for zero-order kinetics, whereas an Arrhenius equation based on the hematite consumption is considered for the first-order model. Also, the model considered the conjugate heat transfer and the species’ melting during the reaction. The finite-volume method was employed to discretize and solve the governing equations. For that, a C++ algorithm was developed in the OpenFOAM software. It was found that a decrement in the pre-exponential factor and kinetic constant reduced temperatures and combustion front velocities. Experimental validation was performed by comparing numerical temperatures and combustion front velocities with data found in the literature. Results indicated a good agreement between numerical and experimental results for both models. Consequently, simulations indicated that employing either a zero or first-order kinetics could produce similar results concerning temperatures and combustion velocities. However, the first-order model presented a difficult ignition and could not propagate the reaction with a low pre-exponential factor. Thus, the zero-order approach could be more feasible to investigate numerically thermite systems in which the primary focuses are the temperatures and combustion velocities.
Keywords
Heat transfer, CFD Simulation using OpenFoam, chemical kinetics, thermite, aluminothermic reaction
