Effect of hydrogen on hydrogenemethane turbulent non-premixed flame under MILD condition Amir Mardani*, Sadegh Tabejamaat Department of Aerospace engineering, Amirkabir university of technology (Tehran polytechnic), Hafez Ave., PO. Box: 15875-4413, Tehran, Iran article info Article history: Received 24 April 2010 Received in revised form 15 June 2010 Accepted 19 June 2010 Available online 7 August 2010 Keywords: MILD combustion Hydrogen Turbulent non-premixed combustion Flame structure Dilution abstract Energy crises and the preservation of the global environment are placed man in a dilemma. To deal with these problems, finding new sources of fuel and developing efficient and environmentally friendly energy utilization technologies are essential. Hydrogen contain- ing fuels and combustion under condition of the moderate or intense low-oxygen dilution (MILD) are good choices to replace the traditional ones. In this numerical study, the turbulent non-premixed CH 4 þH 2 jet flame issuing into a hot and diluted co-flow air is considered to emulate the combustion of hydrogen containing fuels under MILD condi- tions. This flame is related to the experimental condition of Dally et al. [Proc. Combust. Inst. 29 (2002) 1147e1154]. In general, the modelling is carried out using the EDC model, to describe turbulenceechemistry interaction, and the DRM-22 reduced mechanism and the GRI2.11 full mechanism to represent the chemical reactions of H 2 /methane jet flame. The effect of hydrogen content of fuel on flame structure for two co-flow oxygen levels is studied by considering three fuel mixtures, 5%H 2 þ95%CH 4 , 10%H 2 þ90%CH 4 and 20% H 2 þ80%CH 4 (by mass). In this study, distribution of species concentrations, mixture frac- tion, strain rate, flame entrainment, turbulent kinetic energy decay and temperature are investigated. Results show that the hydrogen addition to methane leads to improve mixing, increase in turbulent kinetic energy decay along the flame axis, increase in flame entrainment, higher reaction intensities and increase in mixture ignitability and rate of heat release. ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. 1. Introduction Prediction of oil crises and environmental emission problems of fossil fuels has encouraged the researchers toward diver- sifying our energy supply and more efficient combustion process. To deal with these issues, there has been an effort to develop alternative fuels. Consequently, hydrogen has received special attention as a potential solution to the alter- native fuel. Hydrogen is a clean fuel without any CO, CO 2 , SO x and UHC emission. Also, hydrogen possesses considerable advantages of ignitability, lower ignition delay time and higher flame stability in comparison to hydrocarbon fuels. Burbano et al. [1] reported that the hydrogen will be the main energy source of the world between 2030 and 2040. Further- more, hydrogen could be used as additive to the other fuels such as hydrocarbon and low colorific fuels to improve their combustion characteristics like flame stability and ignit- ability. In this way, some investigations are carried out on characteristics of hydrogenehydrocarbon blends [2e5]. However, to have hydrogen as a practical fuel some problems such as storage, safety and cost should be solved. The storage and safety technological challenges of hydrogen usage are due * Corresponding author. Tel.: þ98 2144508457; fax: þ98 2166404885. E-mail address: amir_mardani@aut.ac.ir (A. Mardani). Available at www.sciencedirect.com journal homepage: www.elsevier.com/locate/he international journal of hydrogen energy 35 (2010) 11324 e11331 0360-3199/$ e see front matter ª 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.ijhydene.2010.06.064