Effects of ammonia energy fraction on combustion stability and emissions characteristics of naturally aspired industrial dual-fuel diesel engine

Abstract

In the era of reducing the combustion of fossil fuels and caring for the natural environment, the search for new environmentally friendly fuels is underway. Limiting GHG emissions is possible by phasing out carbon-based fuels. Ammonia is a very promising zero-carbon fuel and serves as a good carrier for hydrogen. However, due to its high auto-ignition temperature, it requires the use of additional fuel with higher reactivity to initiate ignition. In this study, ammonia was used as a substitute for diesel fuel to power an industrial compression-ignition engine. The results obtained indicated that NH3 does not cause a significant increase in cylinder pressure and improves combustion efficiency. An increase in peak heat release rate was observed. Increasing the proportion of NH3 up to 23% slightly shortened the ignition delay time and then prolonged it for higher NH3 proportions. The combustion duration increased with the increasing proportion of ammonia. It was found that with the increase in NH3 proportion, the variability of the 50% heat release angle (CA50) and the arbitrary end of combustion (CA90) increased, while it did not affect the repeatability of the start of combustion (CA10). It has a favorable effect on specific energy consumption and engine efficiency. The inclusion of ammonia has a very beneficial effect on soot emissions.