Abstract
Ammonia is garnering significant interest from the international maritime sector as an alternative fuel. It is attractive as a hydrogen carrier and as a fuel because it has a higher volumetric energy density compared with gaseous or liquid hydrogen, making it easier to store and transport without requiring high pressures or cryogenic storage. Ammonia has significant toxicity concerns, but safe handling procedures have already been established because it is one of the most widely produced chemicals worldwide for use as a fertilizer. Barriers to consuming NH3as a fuel in engines include (1) less favorable ignition energy and flame speed compared with conventional fuels; (2) emissions challenges, including potentially high NH3, NOX, and N2O emissions; and (3) fuel delivery and handling challenges. Although NH3has been used to fuel compression-ignition marine engines in limited demonstration projects, technical barriers still exist. The use of NH3as a fuel in smaller-bore, high-speed auxiliary engines for large vessels and for smaller inland and coastal marine applications remains unaddressed. This work investigates a late-injection diesel pilot ignition dual-fuel NH3strategy using a single-cylinder, high-speed Cummins four-stroke diesel engine platform with a 107 mm bore and 1.1 L displacement per cylinder. The engine was modified for port fuel injection of heated gaseous anhydrous NH3. The diesel fuel injection system and the combustion geometry were unmodified to represent a retrofit application, which would minimize additional hardware to maximize diesel fuel displacement with NH3. The results show the applicability of a late injection diesel pilot strategy to overcome the challenging fuel properties of NH3over the engine operating envelope. Mapping results focusing on emissions are presented, and comparisons are made to a conventional diesel combustion baseline.
| Original language | English |
|---|---|
| Pages (from-to) | 1951-1962 |
| Number of pages | 12 |
| Journal | International Journal of Engine Research |
| Volume | 26 |
| Issue number | 12 |
| DOIs | |
| State | Published - Dec 2025 |
Funding
This article has been authored by UT-Battelle, LLC, under contract DE-AC05-00OR22725 with the U.S. Department of Energy (DOE). The U.S. government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this manuscript, or allow others to do so, for U.S. government purposes. DOE will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ). The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by the U.S. Department of Energy’s Vehicle Technologies Office—Kevin Stork and Gurpreet Singh, technology and program managers—and the U.S. Department of Transportation’s Maritime Administration—Galen Hon and Will Nabach, program managers. The author(s) disclosed receipt of the following financial support for the research, authorship, and/or publication of this article: This work was funded by the U.S. Department of Energy’s Vehicle Technologies Office—Kevin Stork and Gurpreet Singh, technology and program managers—and the U.S. Department of Transportation’s Maritime Administration—Galen Hon and Will Nabach, program managers. The authors would like to acknowledge technical support from Cummins and from Steve Whitted, Scott Palko, Jonathan Willocks, Vitaly Prikhodko, Gurneesh Jatana, Jim Szybist and Derek Splitter at Oak Ridge National Laboratory.
Keywords
- NH
- Ship engines
- alternative fuels
- ammonia
- dual-fuel combustion
- marine diesel engines
- maritime transportation