Perpustakaan Digital ITB

The imperative to minimize environmental impact while maintaining the efficiency of gas turbine systems has driven significant research into the mechanisms of nitrogen oxides (NOx) formation, which are prominent pollutants emitted during the combustion processes in gas turbines. This undergraduate thesis advances the understanding of NOx emissions through detailed Computational Fluid Dynamics (CFD) simulations utilizing ANSYS Fluent, focusing on the behavior of NOx under various combustion conditions within gas turbine combustion chambers. The research meticulously models the combustion process, applying the non-premixed combustion model in ANSYS Fluent to analyze how different operational parameters—such as equivalence ratios and swirl numbers—influence NOx formation. By simulating different configurations of air and fuel introduction into the combustion chamber, this research explores the conditions that lead to the formation of NOx. The research findings indicate that controlling equivalence ratios and swirl numbers significantly affects NOx emissions in gas turbine combustion chambers. It is found that the optimal equivalence ratio is ????=0.6 which results in an outlet average NO of 21.19 ppm. Equivalence ratios near stoichiometric conditions (0.8 ? ? ? 1.0) lead to high NOx formation, whereas operating with lean (? = 0.6 or lower) or rich (? > 1.4) mixtures reduces NOx emissions by affecting flame temperatures and the availability of oxygen and nitrogen.. The most optimal setting for swirl number is ????????=0.46 or a swirl angle of 30° which results in an outlet average NO of 15.98 ppm. Swirl numbers less than 0.4 result in increased NOx due to inadequate mixing and a lack of an Inner Recirculation Zone (IRZ), causing higher temperature concentrations and prolonged exposure of nitrogen and oxygen to combustion conditions favorable for NOx formation. Conversely, swirl numbers greater than 0.4 enhance the formation of an IRZ, promoting more uniform temperature distributions and reduced high-temperature exposure, thus decreasing NOx emissions.