Potential Fuel Economy Improvements from the Implementation of cEGR and CDA on an Atkinson Cycle Engine

EPA has been benchmarking engines and transmissions to generate inputs for use in its technology assessments supporting the Midterm Evaluation of EPA’s 2017-2025 Light-Duty Vehicle greenhouse gas emissions assessments. As part of an Atkinson cycle engine technology assessment of applications in light-duty vehicles, cooled external exhaust gas recirculation (cEGR) and cylinder deactivation (CDA) were evaluated. The base engine was a production gasoline 2.0L four-cylinder engine with 75 degrees of intake cam phase authority and a 14:1 geometric compression ratio. An open ECU and cEGR hardware were installed on the engine so that the CO₂ reduction effectiveness could be evaluated. Additionally, two cylinders were deactivated to determine what CO₂ benefits could be achieved. Once a steady state calibration was complete, two-cycle (FTP and HwFET) CO₂ reduction estimates were made using fuel weighted operating modes and a full vehicle model (ALPHA) cycle simulation. This paper presents the results from implementation of cEGR and CDA on an engine capable of Atkinson cycle operation.