Optimizing combustion in an opposed-piston, two-stroke (OP2S) diesel engine

This study examines how Achates Power has developed the optimal combustion system for its OP2S engine through the:

● Experimental selection and identification of the best performance within the required limits for piston temperatures that are designed for modern, heavy-duty engine durability requirements

● Correlation of combustion computational fluid dynamics (CFD) to single-cylinder engine measurement results and determination of the right merit function with regard to fuel consumption, emissions and heat rejection

● Use of Genetic Algorithms (GAs) in CFD to iterate the combustion system of an OP2S engine within the available design space in order to further enhance performance

The study also provides an overview of the latest Achates Power engine performance and emissions results versus published data from the Ford Power Stroke benchmark engine. That data demonstrates best brake thermal efficiency of 48.3 percent, an increase of seven percentage points over the Ford engine. It also shows a very flat fuel map, which results in a 24 percent brake-specific fuel consumption reduction.

Finally, the study briefly highlights some of the fundamental OP2S advantages including

● Favorable surface-to-volume ratio

● Leaner combustion

● Shorter and earlier combustion