Stability Analysis of an Ammonia-Based Emulsion With Additives for Lean Combustion

In recent years, considerable progress has been made in exploring new fuel additives to reduce emissions and improve combustion performance compared to conventional fuels. Reducing total nitrogen oxide (NOx) emissions can be achieved by reducing the flame temperature using a fuel emulsified with water and/or using ammonia-based nano-additives such as urea. For the preparation of emulsified fuel, it is desirable to achieve greater stability of the emulsified fuel with a minimum cost of chemicals and energy, so that it can be used for a longer period. The stability of an emulsion is influenced by the water-fuel ratio and the amount of surfactant. In the present work, the influence of dispersed urea nanoparticles, water, and surfactant (Span 85/Tween 80) on the combustion performance and emission characteristics of aviation fuel has been investigated. The experimental campaign was carried out in a 300-kW swirled turbine combustor. It consists of a cylindrical combustion chamber with three optical windows, equipped with pressure sensors, thermocouples, and an exhaust gas analyzer. The experimental campaign was conducted with the same air/fuel ratio (Φ) to facilitate the comparison of different emulsions. The focus is on the stability of the emulsion with the use of surfactants. Chemiluminescence imaging was performed to characterize the effects of the additive on flame emissions. A spectrometer was also used to verify the presence of particulate matter under different fuel conditions. Finally, NOx, CO, CO2, and O2 emissions were measured.