Recent Advances in Opposed Piston Engines for Ultralow Emissions

Abstract

Over the last several years, the development and demonstration of opposed-piston (OP) engines has advanced rapidly. This paper presents results of the Heavy Duty Diesel Demonstration Program, funded by the California Air Resources Board, that provide evidence a diesel OP engine can achieve ultralow levels of tailpipe NOx while also reducing fuel consumption (and CO2 emissions) compared to a reference vehicle using a modern, conventional diesel engine. It is important to note that the OP engine achieved these results using only conventional, underfloor aftertreatment systems. No additional emissions control technologies were required.