Numerical Investigation on Hydrogen-Blended Methane Combustion in a MILD Combustor

Abstract

This study numerically investigates the combustion characteristics of pure methane and hydrogen-blended methane in a MILD (moderate or intense low-oxygen dilution) combustor. Three different combustion models, namely the chemical equilibrium, steady diffusion flamelet and eddy dissipation concept, were employed with the use of ANSYS Fluent 18.1 software. The chemical equilibrium and steady diffusion flamelet models failed to agree with the experimental data of the pure methane case, while the eddy dissipation concept model showed the best agreement with the experimental data. The hydrogen addition ratio to methane was varied from 10% to 40% on molar basis. Two different sets of the hydrogen addition studies, which were the constant power and the constant methane consumption cases, were conducted in the simulations. The obtained results reveal that the hydrogen addition makes the combustion flame more compact and increases the reaction rate of methane, which in turn reduces the MILD combustion characteristics of the combustor.

Keywords

• MILD combustion
• Hydrogen fuel
• Combustion mode

Oksijen Seyreltmeli Bir Yakıcıda Hidrojen Karışımlı Metan Yanmasının Nümerik Olarak İncelenmesi

Abstract

Bu çalışmada nümerik olarak oksijence seyreltilmiş bir yakıcıdaki saf metan ve hidrojen karışımlı metanın yanma karakteristikleri incelenmiştir. ANSYS Fluent 18.1 yazılımın kullanımı ile kimyasal denge, kararlı difüzyon alevi ve eddy yayılım konsepti modelleri kullanılmıştır. Kimyasal denge ve kararlı difüzyon alevi modelleri saf metana ait deneysel verilerle uyumsuzluk gösterirken, eddy yayılım konsepti modeli deneysel verilerle en uygun sonuçları vermiştir. Çalışmada metana hidrojen katkısı molar olarak %10’dan %40’a kadar olmuştur. Hidrojen katkısı için nümerik çalışmalar sabit ısıl güç ve sabit metan tüketimi olmak üzere iki grupta yapılmıştır. Elde edilen sonuçlar göstermektedir ki metana hidrojen katkısı yanma alevini daha kompakt hale getirmektedir ve metan yakıtının reaksiyon hızını arttırmaktadır. Bu durumda da yakıcı ortamdaki oksijence seyreltilmiş düşük sıcaklıklı yanma karakteristiği azaltılmaktadır.

Keywords

• Seyreltmeli yanma
• Hidrojen yakıtı
• Yanma modu

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