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A Study of Structure and Entropy Generation in Confined Biogas Coflow Diffusion Flames
Nivethana Kumar R., Muthu Kumaran S.,
Published in Springer Science and Business Media Deutschland GmbH
2023
Pages: 517 - 534
Abstract
Biogas is primarily composed of methane, carbon dioxide and other gases in trace amounts. The amount of CO2 present in biogas varies with the source of biomass and the method of production. The CO2 content in biogas significantly affects the flame stability. In the present work, comprehensive numerical study of structure, stability and characteristics of confined coflow biogas diffusion flames are presented. A short reaction mechanism with 25 species participating in 121 reactions is used to model reactive flow. Numerical simulations are carried out using OpenFOAM. Fick’s diffusion, thermal diffusion and variable thermophysical properties are incorporated in the model. Biogas with 55% methane (rest carbon dioxide) is considered in the present study. The burner is operated at 250 W. The primary air is systematically increased from 5 to 40% of the stoichiometric air requirement. The rate of coflow air is fixed as the stoichiometric value in one set of cases. Subsequently, the rate of coflow air is varied such that the total air supplied is equal to the stoichiometric value. Results indicate that the flame stability increase with an increase in the amount of primary air flow rate in the fuel stream. The stability is seen to be better in cases where total airflow to the burner is equal to the stoichiometric value. Entropy generation during processes such as chemical reactions, mass diffusion, heat transfer and coupled heat and mass transfer are discussed in detail. Results in terms of velocity, temperature, species and entropy fields are used to describe the stability and flame characteristics of confined coflow biogas flames. © 2023, The Author(s), under exclusive license to Springer Nature Singapore Pte Ltd.
About the journal
JournalLecture Notes in Mechanical Engineering
PublisherSpringer Science and Business Media Deutschland GmbH
ISSN21954356
Open AccessNo