• Citer

Burning ammonia–hydrogen mixtures in a staged combustor with high efficiency and low pollutant emissions

par Piscopo, Alessandro ;Giuntini, Lorenzo ;Novelli, Chiara ;De Paepe, Ward ;Coussement, Axel ;Parente, Alessandro
Référence International journal of hydrogen energy, 118, page (343-355)
Publication Publié, 2025-05-01

Article révisé par les pairs

• Accès en ligne
• Détails
• Contenu
• Statistiques

Résumé :

The urgent need to reduce our dependence on fossil fuels requires a massive transition toward renewable energy. Yet, directly using renewable electricity is challenging for heavy industries needing huge amounts of heat and high process temperatures, conditions realistically achievable only through combustion. In this scenario, sustainable fuels offer a promising pathway for decarbonizing hard-to-abate sectors, and fuel mixtures with varying compositions are expected to become the norm. To support this shift, fuel-flexible technologies will be crucial to ensure steady operation without affecting efficiency and pollutant emissions. Among various carbon-free fuels, ammonia has gained considerable attention as a hydrogen carrier due to its more favorable storage requirements. However, its low reactivity and tendency to produce NOx and N2O requires tailored fueling strategies to improve flame stability and limit emissions. Blending ammonia with hydrogen addresses reactivity issues, while staged combustion may be effective for achieving low pollutants and high efficiency. A novel burner design combining a stagnation-point reverse-flow (SPRF) chamber with air staging showed promising low emissions in initial tests; therefore, further investigation on the performance of this combustor prototype is needed. In this work, we tested such a novel design on a much wider operating space in terms of equivalence ratio in the rich region, operating pressure and ammonia/hydrogen composition in the fuel. Computation Fluid Dynamics (CFD) simulations were performed to characterize the combustor performance over this operating space. A surrogate model based on Polynomial Chaos Expansions (PCE) was then developed and trained on CFD data to capture the highly non-linear relationships between the operating parameters and pollutant emissions. After validation, the PCE model was used to identify optimal regions for low-emission combustion. The results demonstrated that the proposed combustor design is robust with stable NOx + N2O emission below 100 ppmv at 16% O2 over a wide range of input parameters, thereby offering the operational flexibility needed to boost the use of green fuels in the industry.