Fennell, D., Herreros, J., Tsolakis, A., Xu, H. et al., "GDI Engine Performance and Emissions with Reformed Exhaust Gas Recirculation (REGR)," SAE Technical Paper 2013-01-0537, 2013, doi:10.4271/2013-01-0537.
Exhaust Gas Fuel Reforming has potential to be used for on-board generation of hydrogen rich gas, reformate, and to act as an energy recovery system allowing the capture of waste exhaust heat. High exhaust gas temperature drives endothermic reforming reactions that convert hydrocarbon fuel into gaseous fuel when combined with exhaust gas over a catalyst - the result is an increase in overall fuel energy that is proportional to waste energy capture.The paper demonstrates how the combustion of reformate in a direct injection gasoline (GDI) engine via Reformed Exhaust Gas Recirculation (REGR) can be beneficial to engine performance and emissions. Bottled reformate was inducted into a single cylinder GDI engine at a range of engine loads to compare REGR to conventional EGR. The reformate composition was selected to approximate reformate produced by exhaust gas fuel reforming at typical gasoline engine exhaust temperatures. The decision was guided by data from experimental work carried out by Johnson Matthey using a reforming catalyst developed for the fuel reforming application.The engine test results show improved combustion stability with REGR; this allows for higher recirculation rates and increased combustion mixture dilution. This is significant as it could allow for a higher fraction of fuel to be reformed, and therefore waste energy captured. REGR results in a large NOx reduction and a reduction in HCs relative to EGR. The effects of REGR on Particulate Matter (PM) emissions were also analysed, concluding that REGR reduces PM mass compared to conventional EGR.