SwRI develops D-EGR demonstrator highlighting fuel-efficient, cost-effective engine; 10% and above fuel economy improvements
Southwest Research Institute (SwRI) has built a demonstrator vehicle, based on a 2012 Buick Regal GS, incorporating the latest D-EGR (dedicated EGR) technology (earlier post), an outgrowth of SwRI’s HEDGE (High Efficiency Dilute Gasoline Engine) consortium projects (earlier post). The vehicle is currently delivering about a ~13% improvement on the FTP and 10% on the HwFET cycles, according to Dr. Terry Alger, SwRI Assistant Director, Engine & Vehicle R&D, Engine, Emissions & Vehicle Research.
Staff at the non-profit research organization presented it with little fanfare to the SwRI board of directors and advisory trustees along with 7 other research projects at the 66th annual meeting on Monday. The demonstrator will be present at the upcoming SAE 2014 High Efficiency IC Engine Symposium in Detroit in April; SwRI engineers are presenting a paper (2014-01-1190) at the SAE 2014 World Congress on the development of the demonstrator’s engine.
D-EGR is an engine and control concept that combines fuel reforming to produce hydrogen with high levels of exhaust gas recirculation (EGR) to achieve very high levels of thermal efficiency. In 2013, SwRI reported a 2.0-liter engine running as a full D-EGR engine from idle to full load, delivering more than 42% brake thermal efficiency with ultra-low exhaust emissions.
To accomplish reformation of the gasoline in a cost-effective, energy efficient manner, a dedicated cylinder is used for both the production of EGR and reformate. By operating the engine in this manner, many of the sources of losses from traditional reforming technology are eliminated and the engine can take full advantage of the benefits of reformate.
As will be presented at SAE World Congress, SwRI engineers modified the 2.0-liter engine in the demonstrator to add:
- the dedicated EGR loop;
- an additional injector for delivering extra fuel for reformation;
- a modified boost system that included a supercharger;
- high energy dual coil offset (DCO) ignition; and
- other actuators used to enable the control of D-EGR combustion.
The compression ratio of the engine was increased to 11.7:1 to take advantage of the improved knock resistance from reformate and EGR.
The conversion to D-EGR improved engine efficiency by at least 10% across the performance map, with some operating conditions seeing substantially higher improvements, as noted above.
The SwRI team will report that the brake specific fuel consumption (BSFC) at 2000 rpm 2 bar BMEP improved from 385 g/kW-h in the series production state to 330 g/kW-h; the lowest BSFC for the engine was 212 g/kWh compared to 236 g/kW-h for the series engine.
The addition of 2-stage boosting also allowed the engine to meet its torque targets of at least 17 bar BMEP from 1500-5500 rpm while maintaining good transient response and low engine-out emissions.
Last February, PSA Peugeot Citroën announced that it will commercialize high-efficiency gasoline engines featuring dedicated exhaust gas recirculation (D-EGR). At that time, PSA said it expected the new D-EGR engines, due to be available in PSA vehicles by 2018, would consume 10% less fuel than their predecessors across all uses. PSA has been a member of the HEDGE consortium (now at HEDGE-III) since 2004.
Christopher Chadwell, Terrence Alger, Jacob Zuehl, Raphael Gukelberger (2014) “A Demonstration of Dedicated EGR on a 2.0 L GDI Engine,” (SAE 2014-01-1190)