CFD Investigation into Hydrogen-Ammonia Stratification Combustion in IC Engine

An CFD (Computational Fluid Dynamics) investigation and analysis into flame propagation of hydrogen-ammonia and air mixture for justifying the feasibility of using ammonia-hydrogen blend to the decarbonisation purpose on IC engines was undertaken. With AVL Fire M CFD model based on a modification Liebherr D936 engine for dual fuel combustion, hydrogen and ammonia stratification mixing and combustion process with premixed ammonia-air mixture and direct injection hydrogen were examined. The key findings included that a). The flame propagation speed increase between a 100%vol and 90%vol ammonia-hydrogen mixtures is of minimal benefit and larger doping ratios are required; b). A 60%–40%vol ammonia-hydrogen blend could be a suitable substitute for a minimally altered compression ignition engine, because of near flame speed parity with diesel; c). Emissions of NO and unburnt ammonia released from such mixture and combustion conditions are higher than expected level, requiring careful emissions control through optimising operating parameters and combustion process.