Evaluation of numerical modeling and combustion characteristics of hydrogen oxy-fuel combustion in a semi-industrial furnace

• Published in: Fuel (Guildford) 2024-08, Vol.369, p.131690, Article 131690
• Main Authors: Daurer, Georg, Schwarz, Stefan, Demuth, Martin, Gaber, Christian, Hochenauer, Christoph
• Format: Article
• Language: English
• Subjects: Computational fluid dynamics; Hydrogen; Oxy-fuel combustion; Semi-industrial furnace
• ISSN: 0016-2361; 1873-7153
• DOI: 10.1016/j.fuel.2024.131690

The use of hydrogen (H2) in oxy-fuel combustion (OFC) systems is a promising concept for future high-temperature industries. However, the current literature lacks a comprehensive study on the numerical modeling aspects and the relevant flame characteristics. This was tackled in the present work, as the high-impulse OFC of pure H2 was analyzed for the first time in an industrial environment based on experiments, theoretical calculations and RANS simulations. A detailed 3D CFD model of a 180 kW furnace was developed in Fluent, focusing on an accurate prediction of the temperature field and heat transfer rates. An extensive model validation was accomplished using measurement data from the conventional OFC of methane (CH4), and highly precise results could be obtained. Then, the numerical modeling of H2 OFC was scrutinized, highlighting the influence of different CFD modeling options for turbulence, combustion chemistry and thermal radiation. In the end, a detailed analysis of the combustion characteristics has been performed, using the conventional OFC of CH4 as a reference. It was found that turbulence modeling has the dominating effect on the numerical representation of the flame, while only negligible changes were noticed with different combustion and radiation models. Precise simulation results were achieved only by incorporating novel adaptations of the k-ɛ model, since the turbulent diffusion was underestimated with all common turbulence models. In terms of the flame characteristics, H2 caused an increase in the peak flame temperature by 400 K relative to CH4, which led to an improved radiative heat transfer in the flame near region. At the same time, the flame length decreased by almost 10% despite three-times higher fuel nozzle velocities. Overall, thorough insights into both the numerical modeling and the combustion characteristics of H2 OFC were provided, which should support the move toward greater sustainability in high-temperature processes. •CFD based study of industrial H2 oxy-fuel setup in a 180 kW combustion chamber.•Extensive model validation to achieve accurate temperatures and heat transfer rates.•Influence of turbulence, combustion and radiation modeling with RANS approach.•Comparison of the combustion characteristics between CH4 and H2 oxy-fuel setup.•Substantial increase in peak flame temperatures and decrease in flame lengths with H2.