Graphical Abstract AbstractExhaust gas fuel reforming has been identified as a thermochemical energy recovery technology with potential to improve gasoline engine efficiency, and thereby reduce CO2 in addition to other gaseous and particulate matter (PM) emissions. The principle relies on achieving energy recovery from the hot exhaust stream by endothermic catalytic reforming of gasoline and a fraction of the engine exhaust gas. The hydrogen-rich reformate has higher enthalpy than the gasoline fed to the reformer and is recirculated to the intake manifold, i.e. reformed exhaust gas recirculation (REGR).The REGR system was simulated by supplying hydrogen and carbon monoxide (CO) into a conventional EGR system. The hydrogen and CO concentrations in the REGR stream were selected to be achievable in practice at typical gasoline exhaust temperatures. Emphasis was placed on comparing REGR to the baseline gasoline engine, and also to conventional EGR. The results demonstrate the potential of REGR to simultaneously increase thermal efficiency, reduce gaseous emissions and decrease PM formation.

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Exhaust gas fuel reforming has the potential to improve the thermal efficiency of internal combustion engines, as well as simultaneously reduce gaseous and particulate emissions. This thermochemical energy recovery technique aims to reclaim exhaust energy from the high temperature engine exhaust stream to drive catalytic endothermic fuel reforming reactions; these convert hydrocarbon fuel to hydrogen-rich reformate. The reformate is recycled back to the engine as Reformed Exhaust Gas Recirculation (REGR), which provides a source of hydrogen to enhance the engine combustion process and enable high levels of charge dilution; this process is especially promising for modern gasoline direct injection (GDI) engines. This paper presents a full-scale prototype gasoline reformer integrated with a multi-cylinder GDI engine. Performance is assessed in terms of the reformate composition, the temperature distribution across the catalyst, the reforming process (fuel conversion) efficiency and the amount of exhaust heat recovery achieved.

Exhaust gas fuel reforming is a catalytic process that reclaims exhaust energy from the high temperature engine exhaust stream to drive catalytic endothermic fuel reforming reactions; these convert hydrocarbon fuel to higher enthalpy hydrogen-rich gas known as reformate. This technique has the potential to improve the thermal efficiency of internal combustion engines, as well as to simultaneously reduce gaseous and particulate emissions. This study demonstrates a novel, prototype exhaust gas fuel reformer integrated with a modern, turbocharged, 4-cylinder gasoline direct injection engine and analyses the effects on engine performance, combustion characteristics and emissions. The results suggest that exhaust gas fuel reforming raises the engine fuel efficiency through a combination of: exhaust energy recovery; improved engine thermal efficiency; and enhanced combustion at highly dilute operation, which considerably reduces NO x emissions by up to 91% and improves engine fuel consumption by up to 8%. The presence of hydrogen and exhaust gas diluents in the combustion charge also reduces particle formation for lower total particulate matter emissions (up to 78% and 84% for number and mass, respectively).

An index, linking fuel composition with Particulate Matter (PM) emissions (PN index) has been developed and here is evaluated with model fuels in a single cylinder, optical access, Spray Guided Direct Injection (SGDI) engine. Imaging of in-cylinder evaporation shows the composition of model fuels affects their PM emissions.Emissions are evaluated from two fuels representing the EU5 reference-fuel specification, developed using the PN index to give a difference in PM emissions, showing a 40% variation.The index is investigated in a Jaguar V6 engine with five different fuels over a simulated NEDC. The results show the index trends are followed.