Date

2023-1-25

Author

Kıymaz, TAHSIN BERK

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Global interest in hydrogen as an energy carrier for combustion and fuel cell applications to reduce CO2 emissions is expanding. However, the use of 100% hydrogen in combustion applications is still technologically and logistically immature, necessitating substantial adjustments to infrastructures linked to hydrogen generation, transfer, and conversion. Thus, blending hydrogen is considered as a preliminary approach on this transition. This work investigates laminar flame propagation of natural gas - air and natural gas - hydrogen - air premixtures in a spherical combustion chamber, both experimentally and numerically. H2 addition rates up to 20% are investigated at atmospheric conditions for lean and stoichiometric conditions. A spherical combustion chamber is designed, manufactured, and commissioned to investigate spherical laminar flame propagation. Experiments were performed at 1bar and at 288 ± 2K. The experimental setup consists of a high-pressure combustion chamber, a Schlieren visualisation system and a high-speed video camera for flame images recording. Captured images are post processed to obtain flame radius in each frame. Linear methodology is used to extrapolate the experimentally measured stretched laminar burning velocities to the unstretched ones. The laminar flame speeds of the investigated mixtures are compared with the literature results and 1D and 2D numerical simulations. It is shown that the laminar flame speeds of NG-air mixtures increase with hydrogen addition to the fuel. Additionally, laminar boundary layer flame flashback is investigated numerically. 2D transient computations were performed up to 20% hydrogen addition rate into methane-air mixtures for 300K and 600K wall temperatures. Laminar flashback limits were calculated; it is found that flashback propensity increases with increasing wall temperature and increasing hydrogen addition rate. The quenching distance decreases with hydrogen addition to the mixture.

Subject Keywords

Laminar Premixed Flames, Laminar Flame Speed, Spherically Expanding Flames, Hydrogen Enriched Natural Gas, Flame Flashback, Schlieren Visualisations, OpenFOAM 2D Flame Simulations

URI

https://hdl.handle.net/11511/101912

Collections

Graduate School of Natural and Applied Sciences, Thesis