Reactive structures and NOx emissions of methane/hydrogen mixtures in flameless combustion
| Autor: | Marco Ferrarotti, W. De Paepe, Alessandro Parente |
|---|---|
| Jazyk: | angličtina |
| Rok vydání: | 2021 |
| Předmět: |
Physique de l'état condense [struct. électronique
etc.] Hydrogen 020209 energy Mixing (process engineering) Energy Engineering and Power Technology chemistry.chemical_element 02 engineering and technology NOx Physique de l'état condense [struct. propr. thermiques etc.] Combustion Sciences de l'ingénieur 7. Clean energy Methane PaSR law.invention Technologie des autres industries chemistry.chemical_compound Natural gas law 0502 economics and business 0202 electrical engineering electronic engineering information engineering 050207 economics Physique de l'état condense [supraconducteur] Renewable Energy Sustainability and the Environment business.industry Flameless 05 social sciences Injector Technologie des hydrocarbures carbochimie MILD Condensed Matter Physics Dilution Fuel Technology Chemical engineering chemistry 13. Climate action business |
| Zdroj: | International journal of hydrogen energy International Journal of Hydrogen Energy |
| Popis: | Methane/hydrogen combustion represents a concrete solution for the energy scenario to come. Indeed, the addition of hydrogen into the natural gas pipeline is one of the solutions foreseen to reduce CO2 emissions. Nevertheless, the replacement of methane by hydrogen will enhance the reactivity of the system, increasing NOx emissions. To overcome this issue, non-conventional combustion technologies, such as flameless combustion represent an attractive solution. This study aims to improve our understanding of the behaviour of methane/hydrogen blends under flameless conditions by means of experiments and simulations. Several experimental campaigns were conducted to test fuel flexibility for different methane/hydrogen blends, varying the injector geometries, equivalence ratio and dilution degree. It was found that a progressive addition of hydrogen in methane enhanced the combustion features, reducing the ignition delay time and loosing progressively the flameless behaviour of the furnace. Reducing the air injector diameter or increasing the fuel lance length were found to be efficient techniques to reduce the maximum temperature of the system and NOx emissions in the exhausts, reaching values below 30 ppm for pure hydrogen. MILD conditions were achieved up to 75%H2 in molar fraction, with no visible flame structures. Additionally, RANS-based simulations were also conducted to shed further light on the effect of adding hydrogen into the fuel blend. A sensitivity study was conducted for three different fuel blends: pure methane, an equimolar blend and pure hydrogen. The effect of chemistry detail, mixing models, radiation modeling and turbulence models on in-flame temperatures and NOx emissions was also studied. In particular, it was found that the usage of detailed chemistry for NOx, coupled with an adjustment of the PaSR model, filled the gap between experiments and predictions. Finally, a brute-force sensitivity revealed that NNH is the most important route for NOx production. SCOPUS: ar.j info:eu-repo/semantics/published |
| Databáze: | OpenAIRE |
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