Insights Into the Thermal Quenching of Hydrocarbon Flames in Confined Spaces
15 Pages Posted: 4 Aug 2022
Date Written: July 31, 2022
Flame stabilization is a common problem in micro-structured combustion systems. This study relates to the insights into the thermal quenching of hydrocarbon flames in confined spaces. Laminar flame quenching at the wall of a combustion chamber has been studied, using a numerical model to describe the reactive flow. The model combines a steady treatment of the fluid mechanics and a detailed chemical kinetic reaction mechanism. Flame propagation in microchannels is modeled using a two-dimensional computational fluid dynamics model with detailed multicomponent transport, gas-phase chemistry, heat loss through the wall, radical recombination at walls, and possible temperature discontinuity at the wall due to lack of thermal accommodation. Computational fluid dynamics simulations are performed to gain insights into combustion performance such as reaction rates, temperatures, and flames. The factors affecting combustion characteristics are determined. Particular focus is placed on determining essential factors that affect the thermal quenching of hydrocarbon flames in confined spaces. The results indicate that hydrocarbon flames are typically quenched when confined within spaces with critical dimensions less than 2.0 mm, depending on the flow velocity, channel dimensions, and heat losses. Thermal quenching is the loss of energy generated by combustion through heat transfer out of the combustion region. To prevent such thermal quenching, the material forming the wall surfaces must be able to endure and sustain high temperatures. The material must minimize heat loss, so the walls do not remove heat from the combustion chamber. The material chosen must be able to withstand sustained temperatures greater than the ignition temperature. Chemical quenching occurs when the reactive species is removed by reaction with the material forming the combustion chamber wall surfaces. For chemical quenching to be overcome, the material chosen for the walls must have a low well depth.
Keywords: Thermal quenching; Chemical quenching; Hydrocarbon flames; Flame propagation; Confined spaces; Combustion performance
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