Gukelberger, R., Robertson, D., Alger, T., Almaraz, S. et al., "Alternative Fuel Testing on a Port Fuel Injected LPL EGR and D-EGR® Engine," SAE Technical Paper 2016-01-2170, 2016, doi:10.4271/2016-01-2170.
A turbocharged 2.0 L PFI engine was modified to operate in a low-pressure loop and Dedicated EGR (D-EGR®) engine configuration. Both engine architectures were operated with a low and high octane gasoline as well as three ethanol blends. The core of this study focused on examining combustion differences at part and high loads between the selected fuels and also the different engine configurations. Specifically, the impact of the fuels on combustion stability, burn rates, knock mitigation, required ignition energy, and efficiency were evaluated. The results showed that the knock resistance generally followed the octane rating of the fuel. At part loads, the burn rates, combustion stability, and EGR tolerance was marginally improved with the high ethanol blends. When combustion was not knock or stability limited, the efficiency differences between the fuels were negligible. The D-EGR engine was much less sensitive to fuel changes in terms of burn rates than the LPL EGR setup. A sub-task of this work was to investigate differences in D-EGR in-cylinder fuel reformation for the various fuels. It was found that ethanol blends with a high H/C ratio reformed larger H2 amounts for a given D-EGR cylinder equivalence ratio compared to the other fuels.