engleski

Investigation of chemical kinetics of ammonia combustion by numerical simulation

In recent years ammonia appeared as a potential alternative that can be used as a hydrogen vector and fuel for gas turbines and internal combustion engines. Compared to the pure hydrogen ammonia possesses several advantages. It has greater volumetric density and can be liquefied at pressure of about 0.8 MPa at room temperature, similar to propane. There is readily available distribution infrastructure and ammonia is already widely used in agriculture and refrigeration industry. It is also safer for storage and transport due to narrow flammability limit. Also, ammonia can be produced from fossil fuels (making them CO2 neutral), from renewables and from waste heat. Despite the benefits of ammonia as fuel, there are some drawbacks regarding the toxicity and the lower heating value, slower laminar burning velocity and narrower flammability range. Chemical mechanisms of ammonia combustion are important for the development of ammonia combustion systems, but also as a mean of investigation of harmful NOx emissions, so they can be minimized. In spite of large body of experimental and modeling work on the topic of ammonia combustion, there is still need for data for development of new combustion mechanisms. Namely, most of the available ammonia combustion models accurately cover only certain range of operating parameters, such as equivalence ratio, mixture composition and pressure. Taking the above stated, the object of this work will be further study of ammonia/hydrogen combustion chemistry under practical industrial conditions. After literature review, premixed swirl combustor, which burns pure ammonia, was simulated with the aim to compare the performance of three reduced mechanisms of ammonia combustion and validate the numerical framework. It is expected that this study will contribute to enhance the current knowledge by providing new insights in ammonia burning conditions closely resembling those in industrial applications and will help to design real industrial burning systems.

premixed swirl burner ; computational dynamics ; ammonia combustion ; reduced chemical mechanism ; industrial burner

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