Paul James Millington

Thermochemical recovery technology for improved modern engine fuel economy – part 1: analysis of a prototype exhaust gas fuel reformer

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.

On-board thermochemical energy recovery technology for low carbon clean gasoline direct injection engine powered vehicles:

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 NOx 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).

Influence of Three-Way Catalyst on Gaseous and Particulate Matter Emissions During Gasoline Direct Injection Engine Cold-start

The development of gasoline direct injection (GDI) engines has provided a strong alternative to port fuel injection engines as they offer increased power output and better fuel economy and carbon dioxide emissions. However, particulate matter (PM) emission reduction from GDI still remains a challenge that needs to be addressed in order to fulfil the increasingly stricter environmental regulations. A large number of the total particulate emissions during driving cycles are produced during the engine cold-start. Therefore, controlling PM during cold-start events will significantly reduce the final PM output. This research work provides an understanding of PM characterisation from a 2 l four-cylinder GDI engine during cold-start. Gaseous emissions including hydrocarbon (HC) speciation studies are also carried out preand posta Euro 6 compliant three-way catalyst (TWC). In addition, particulate size distribution and total particulate number were recorded for the first 280 seconds after the engine cold-start. Large concentrations of carbon monoxide, propane, acetaldehyde, formaldehyde, ethanol, toluene and ethylene were emitted during the first 70–90 seconds from the engine start. Gaseous emissions were reduced on the catalyst at temperatures higher than 290°C, with the catalyst reaching almost 100% removal efficiency at 350°C. The effect of the TWC on PM emissions has been analysed for the different PM diameter ranges. A reduction of particles smaller than 20 nm was observed as well as a reduction in the accumulation mode. In order to understand the nature of the particles emitted during cold-start, transmission electron microscope (TEM) grids were used for particulate collection at the engine start and after 80 seconds and 140 seconds of engine operation. A peak of 1.4 × 108 particles was produced at the engine start and this steadily reduced to 3 × 107 in 50 seconds. The TEM micrographs showed solid particles with similar fractal-like shapes.