Perpustakaan Digital ITB

This study focuses on the development of an experimental setup for a diffusion flame coflow burner and an analysis of its stability limits. Methane was selected as a primary fuel due to its non-toxic properties, with the ultimate goal of facilitating ammonia-hydrogen combustion. The investigation addresses several key objectives: determining the effects of velocity ratio and equivalence ratio on flame stability and evaluating the burner setup based on experimental results. This research involves setting up a coflow burner system, creating an experiment SOP to ensure a safe experiment environment, conducting experiments to observe the stability limits of methane-hydrogen-air flames under various conditions, and analyzing the flame structures. Results indicate that within the range of the experiment, increasing velocity ratio moves the flame to a more stable region. The experiments showed that no liftoff occurred for (????????)????=10 ???????????? at methane fractions of ????????????4=0.6 and lower, aligning with the higher laminar burning velocity (LBV) of hydrogen compared to methane, while lower fuel flow rates showed no liftoff even at methane fractions of of ????????????4=0.7 and lower. Specifically, at higher methane fractions, the flame exhibits distinct liftoff and reattachment behaviors, highlighting a hysteresis region where both attached and lifted flames coexist depending on the direction of air flow rate changes. Additionally, varying fuel flow rates demonstrated that the lifted flame region expanded with increased fuel flow, necessitating higher velocity ratios to achieve flame stabilization. A Distinction of the flame front is visible when air flowrate is increased form (????????)????=30 ???????????? to (????????)????=40 ????????????, where the flame starts to show characteristics of turbulent flame. Within the experiment global Reynolds range (????????:400?600) which is way lower than the transitional Reynolds of 2100, the existence of turbulence can only be attributed to the burner geometry. The qualitative analysis of flame structures reveals distinct changes in shape and color corresponding to variations in air and fuel flow rates and methane fuel fractions. Additionally, the study identified several geometric and operational challenges in the burner setup, including air flow inlet that produced radial velocity component and empty corners that led to recirculating flows within the burner chamber.