Effect of ammonia energy fractions on combustion stability and engine characteristics of gaseous (ammonia/methane) fuelled spark ignition engine

Non-carbon nature and higher hydrogen energy density of ammonia have gained a lot of interest as an energy asset and green fuel. In this work, the effects of ammonia fuel share and engine operating load on the combustion stability and engine characteristics (combustion and performance) of gaseous (NH3/CH4) fuelled SI engine have been reported. The lower heating value and flame propagation speed of fuel mixture reduce with the increase in ammonia share (0-60% at 8 Nm engine load) and thus results in detrimental engine performance and higher cycle-to-cycle combustion variations (1.36%-14.9% COV of IMEP). A rise in operating load from 8 Nm to 16 Nm increases the flame propagation speed of the fuel mixture (60% ammonia share) and improves engine performance and combustion stability (14.9%-4.3% COV of IMEP). The results of this study indicate that the substitution of methane with ammonia could be maximized at higher engine operating loads to get the benefit of clean fuel utilization.(c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

Automated summary

The non-carbon nature and higher hydrogen energy density of ammonia have attracted attention as an energy asset and green fuel. This study investigates the effects of ammonia fuel share and engine operating load on the combustion stability and engine characteristics of gaseous (NH3/CH4) fuelled SI engine. The results show that higher ammonia share and lower engine load result in detrimental engine performance and higher combustion variations, while higher operating load improves engine performance and combustion stability. Substituting methane with ammonia can be maximized at higher engine operating loads for clean fuel utilization.