Exhaust and aftertreatment on the Achates ULNOx heavy-duty opposed-piston diesel
x (ULNO
x from the opposed-piston engine, which reduced the requirements for the aftertreatment system (ATS).
The original aftertreatment system design which was configured and tested by engineers from Achates Power, Faurecia, Aramco Services, Corning, Southwest Research Institute, and BASF included a light-off SCR using gaseous
ammonia, closely coupled to the engine in the engine compartment, and an under-cab ATS that included a DOC and SCR on filter.
However, during development, the project team was able to exceed the program expectation for engine-out NO
x and exhaust temperature control in the catalyst warm-up mode and concluded that the tailpipe NO