A study published by Japanese researchers has verified the potential of a new fuel injection concept for liquid ammonia in large 2-stroke combustion engines.
Ammonia has a higher auto-ignition temperature and slower laminar burning velocity than conventional marine fuels. This delays the timing of combustion in the cylinders of 2-stroke engines and can result in ammonia slip and the production of NOx and nitrous oxide (N2O).
“J-ENG has carried out research into the combustion of ammonia on NMRI’s 3-cylinder 230mm bore test engine.” “/ / 
Source: NMRI
J-ENG has carried out research into the combustion of ammonia on NMRI’s 3-cylinder 230mm bore test engine.
To overcome these issues, the researchers developed the concept of a three-layer stratified fuel injection process that sandwiches the liquid ammonia between two layers of an easily-ignitable supporting fuel such as marine gas oil or biodiesel.
The concept was verified in experiments where the three layers were injected sequentially from a single nozzle, and a three-layered spray was formed. Analysis of the results indicated that the ammonia was burnt and N2O production was suppressed.
The researchers are planning further experiments aimed at increasing the ammonia energy ratio without increasing N2O emissions.
The study was published in Applications in Energy and Combustion Science by researchers from Japan Engine Corporation (J-ENG), Tohoku University and Japan’s National Maritime Research Institute (NMRI).
The Motorship previously reported onJ-ENG’s plans to carry out research and development of the combustion of hydrogen and ammonia as fuel in collaboration with NMRIin 2019.
The study is available here.
