Study on combustion and explosion mechanism and propagation characteristics of natural gas/ammonia mixed gas fuel

Adding non-carbon fuel to natural gas can effectively reduce carbon emissions. Ammonia, as a carbon-free fuel, has received widespread attention, but there are still some limitations to its direct application. Consider adding ammonia to natural gas and gradually transitioning to carbon-free fuels. This article investigates the deflagration characteristics of natural gas/ammonia (NG/NH₃) mixed fuels with different ratios and concentrations using a gas deflagration characteristic platform. When there are obstacles inside the pipeline, the propagation process of NG/NH₃ mixed fuel deflagration is mainly affected by the reflected pressure wave. As the proportion of ammonia added increases, the deflagration intensity and flame stability of the mixed fuel decrease. The propagation process of NG/NH₃ mixed fuel deflagration shock waves in pipelines can be divided into three stages: slow development stage, stable propagation stage, and wave propagation stage. As the proportion of ammonia added increases, the peak overpressure and total carbon emissions of the mixed fuel monotonically decrease. Considering both carbon emissions and deflagration intensity, a 25 % ammonia blending ratio can be used as a new type of blended fuel with potential application value. In addition, through the study of the chemical reaction kinetics mechanism of NG/NH₃ mixed fuel, it was found that the addition of ammonia changes the sensitivity of various deflagration parameters of NG/NH₃ mixed fuel at different equivalence ratios; The addition of ammonia suppresses the increase in temperature of the reaction system; The addition of ammonia increases the thickness of the deflagration reaction zone, making combustion more complete and improving the combustion efficiency of fuel.