Experimental assessment of hydrogen versus ammonia co-combustion in a dual-fuel diesel engine

Abstract

This work experimentally evaluates the co-combustion of hydrogen and ammonia with diesel fuel in a dual-fuel compression ignition engine. The study examines how varying shares of H₂ and NH₃ affect combustion behavior, engine efficiency, and exhaust emissions, with ignition initiated by a pilot diesel injection. The alternative fuels accounted for 12%, 28%, 36%, and 42% of the total energy supplied to the engine. The results confirm that both hydrogen and ammonia can be successfully applied in dual-fuel diesel engine operation. Relative to neat diesel combustion, the addition of H₂ or NH₃ enhanced indicated thermal efficiency (ITE) and lowered specific emissions of NO (excluding 36% and 42% H₂ share), unburned hydrocarbons, CO₂, and soot. Hydrogen supplementation reduced CO emissions in most cases (except at a 42% H₂ share), whereas ammonia supplementation led to an increase in specific CO emissions. Moreover, the use of hydrogen and ammonia did not result in unacceptable increases in peak pressure rise (PPR) or the coefficient of variation of indicated mean effective pressure (COV_IMEP), except at a 42% H₂ share.