Combustion, emissions, and performance of natural gas–ammonia dual-fuel spark-ignited engine at full-load condition.

In the present study, the full load performance and emission characteristics of natural gas-ammonia dual fuel engine were investigated using the experimental methodologies with three approaches. An 11–l, 6-cylinder turbocharged natural gas engine was used in the experiments and combustion parameters, such as the energy fraction of ammonia, the air-fuel ratio, and the ignition timing, were varied to assess the effect of the introduction of ammonia as a fuel. The experiments are conducted at 1100 rpm and 1000 Nm of brake toque, which is representing the maximum torque. The effect of volumetric fuel flow rate is examined in the consideration of using a certain fuel supply system. A constant flow rate of the intake air condition was evaluated under a maximum brake torque operation condition. Lastly, the thermal efficiency and exhaust gas emissions were observed with varying the air-fuel ratio at 15% of ammonia energy fraction. The experimental results showed that using the existing fuel supply system could not secure the required brake torque and the insufficient time for the complete combustion of natural gas-ammonia mixture resulted in the increase in instability and unburned fuel of combustion. Fuel NOx was dominant of NOx emissions with the introduction of ammonia. • Ammonia addition lowers brake power under constant volume flow rate of fuel. • Initial burn duration become longer with increased ammonia addition. • Ignition timing should be advanced to prevent incomplete combustion. • Fuel NOx is dominant for NOx emission results with small amount of ammonia addition. • NOx emission increases with increased ammonia addition and decreased A/F ratio. [ABSTRACT FROM AUTHOR]