Relative Assessment of Flame Characteristics and Pollutant Levels of Inverse Diffusion and Central Diffusion Flames

Articles in Press

Document Type : Full Length Research Article

Authors

1 Department of Mechanical Engineering, Sardar Vallabhbhai National Institute of Technology, Surat

2 Mechanical Engineering Department, Government Engineering College, Dahod, India

3 Department of Mechanical Engineering, Sardar Vallabhbhai National Institute of technology, Surat

Abstract

Relative performance analysis in terms of flame shape, size, temperature distribution and pollutant levels of non-swirling turbulent, Inverse Diffusion Flame (IDF) and Central Diffusion Flame (CDF) is experimentally studied. Methane gas is used as fuel and air as an oxidizer. In IDF (two inlet system), air enters through the central tube and fuel through the outer coaxial tube. In CDF (three inlet system), another coaxial tube is added around the outer fuel tube and secondary air (annular) is supplied through it. In IDF and CDF, both mass flow rate of air (125 LPM) and mass flow rate of fuel (4 LPM) are kept constant in all cases. In CDF, secondary air flow rate is varied between 5 and 25 percent in 5 percent increments. Flame characteristics such as flame appearance, length, temperature distribution, and emission are measured and compared for IDF and CDF. Secondary air in CDF improves flame stability compared to IDF. Better stability is observed in CDF compared to IDF. Total flame length and blue zone length are less in CDF compared to IDF because the reaction zone shifts towards the flame base as the annular jet of CDF provides additional air for the combustion process. CO emission level decreases with increasing annular air fraction in CDFs. CDF with 10% annular air outperforms in terms of blue zone length, flame length, CO emissions and combustion noise.

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Journal of Heat and Mass Transfer Research

Articles in Press, Accepted Manuscript
Available Online from 08 November 2025

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History

  • Receive Date: 07 August 2024
  • Revise Date: 09 October 2025
  • Accept Date: 08 November 2025

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