Biogas contains more than 50% methane (CH4), is a renewable and eco-friendly fuel produced by bacterial action. Not only is biogas flammable but it also contains inhibitors like carbon dioxide and nitrogen, as well as small amounts of H2, O2, H2S and others. Several associated studies have been conducted in order to examine biogas combustion characteristics in external combustion and flame angle, flame height and dimensionless flame height are the important characteristics in external premixed combustion. This research’s aims were to discover the influences of N2 as it is the second most prevalent inhibitor in biogas by burning stoichiometric fuel mixtures (CH4 and N2 (0%-50% of fuel)) and oxygen in an experimental external premixed combustion burner whose nozzle tip diameter was 5 mm. The burner was connected to a hose from the oxygen tank and another hose from the fuel tank. Two regulators and flowmeters were placed on each tank to monitor the flow supplied to the mixer and burner. The valves were used to stop or open the fluid supply. The outcome flame propagation is then recorded by a high speed camera and then processed through a computer system. The results indicate that N2 influenced the flame angle, flame height and dimensionless flame height. The higher the N2 content inside the fuel, the shorter the flame height and the lower the dimensionless flame height. Moreover, increasing the N2 content created larger the flame angle.

Biogas is one of alternative energy and categorized as renewable energy. The main sources of biogas come from animal waste, garbage, and household waste that are organic waste. Primarily, over 50% of this energy contains methane (CH 4). The other substances or inhibitors are nitrogen and carbon dioxide. Previously, carbon dioxide effect on biogas combustion is already experimented. The result shows that carbon dioxide reduces the flame propagation speed of biogas combustion. Then, nitrogen as an inhibitor obviously also brings some effects to the biogas combustion, flame propagation speed, and flame characteristics. Spark ignited cylinder is used for the premixed biogas combustion research. An acrylic glass is used as the material of this transparent cylinder chamber. The cylinder is filled with methane (CH 4), oxygen (O 2), and nitrogen (N 2) with particular percentage. In this experiment, the nitrogen composition are set to 0%, 5%, 10%, 20%, 30%, 40%, and 50%. The result shows that the flame propagation speed is reduced in regard to the increased level of nitrogen. It can also be implied that nitrogen can decrease the biogas combustion rate.