Performance of a spark ignition engine fueled with ammonia/hydrogen and ammonia/methane

Performance of a spark ignition engine fueled with NH3/H2 and NH3/CH4 is investigated experimentally. A diesel based four-stroke single-cylinder spark-ignition engine with a stroke volume of 412 cm3 and a compression ratio of 13.7 is used. NH3, H2 a nd C H4 a re s upplied f rom h igh p ressure c ylinders a nd a re i njected u sing automobile gaseous fuel injectors. The fuels are mixed in the intake manifold and are delivered to the cylinder. For NH3/CH4, stable combustion is achieved within the equivalence ratio from 0 to 0.50. For NH3/H2, stable combustion is achieved within the equivalence ratio from 0.70 to 0.90. For both NH3/CH4 and NH3/H2, the brake mean effective pressure and the brake thermal efficiency takes a gradual peak with the increase in the NH3 mole fraction in fuel. The NOx concentration jumps up from 3800 ppm for pure CH4 operation to 5500 ppm for the operation with 10 % of NH3. The amount of NOx emission decreases monotonously with the increase in the NH3 mole fraction in fuel due to the reduction effect of NH3. On the contrary, the amount of unburned NH3 increases with the increase in the NH3 mole fraction in fuel, which shown to have close correlation with the quenching layer thickness. © 2021 Japan Institute of Energy. All rights reserved.