Title: Evaluation of electrified airpath configurations for an opposed piston two stroke compression ignition architecture

Authors: Erik Vorwerk; Patrick O'Donnell; Dennis Robertson; Robert Prucka; Benjamin Lawler; Fabien Redon; Ming Huo; Ashwin Salvi

Addresses: Department of Automotive Engineering, Clemson University, 4 Research Drive, Greenville, SC 29607, USA ' Department of Automotive Engineering, Clemson University, 4 Research Drive, Greenville, SC 29607, USA ' Department of Automotive Engineering, Clemson University, 4 Research Drive, Greenville, SC 29607, USA ' Department of Automotive Engineering, Clemson University, 4 Research Drive, Greenville, SC 29607, USA ' Department of Automotive Engineering, Clemson University, 4 Research Drive, Greenville, SC 29607, USA ' Achates Power Inc., 4060 Sorrento Valley Blvd., San Diego, CA 92121, USA ' Achates Power Inc., 4060 Sorrento Valley Blvd., San Diego, CA 92121, USA ' Achates Power Inc., 4060 Sorrento Valley Blvd., San Diego, CA 92121, USA

Abstract: Opposed piston two-stroke (OP2S) diesel engines have shown promise in reducing emissions and increasing efficiency compared to conventional four-stroke diesel engines. Airpath design on this architecture is critical to realising these benefits, as OP2S scavenging and internal composition are primarily controlled by intake and exhaust pressure differentials, and most pumping work is incurred external to the engine cylinder. Using 1-D simulation and an experimentally validated baseline model, this research evaluates the influence of airpath design on steady-state performance metrics of a two-cylinder OP2S engine. First, conventional, electrified, and novel compression and expansion devices are considered, as well as a range of scavenging control devices, to develop four viable airpath architectures. These architectures are then compared across their operating ranges, and a sensitivity analysis is performed on various airpath component efficiencies. Overall, it is found that the best layout investigated consists of an electrically assisted turbocharger with a variable geometry turbine.

Keywords: opposed piston two stroke; two-stroke; OP2S; electrified airpath; sensitivity analysis; electrified turbocharger; compression ignition; diesel engine; pumping work; scavenging control.

DOI: 10.1504/IJPT.2024.138002

International Journal of Powertrains, 2024 Vol.13 No.1, pp.19 - 53

Received: 11 Sep 2022
Accepted: 17 Aug 2023
Published online: 16 Apr 2024 *

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