Abstract
The introduction of various advanced diesel engine technologies has resulted in a substantial increase of the market share of diesel engines. However, control of diesel particulate matter (PM) and NOx emissions remains a significant challenge. Indeed, in order to meet the stringent PM and NOx emission limits proposed by future legislation, more efficient, durable and cost effective aftertreatment devices will be required. Ongoing research by the authors aims to develop a diesel emissions reduction system with enhanced performance by utilisation of hydrogen produced on-board in an exhaust gas assisted diesel fuel reformer. This type of fuel reforming process involves the on-board generation of hydrogen-containing gas by direct catalytic interaction of hydrocarbon fuels with engine exhaust gases. Part of the research involves the investigation of using reformate (i.e. hydrogen-containing gas) to promote soot oxidation and hence improve both the efficiency of the diesel particulate filter (DPF) regeneration process as well as expanding the regeneration temperature window towards lower exhaust gas temperatures.
This paper presents the experimental investigation of DPF regeneration at different temperatures with addition of metered quantities of hydrogen to the exhaust gas flow upstream of the DPF. Initial results have indicated that the addition of quantities of hydrogen that result in hydrogen concentrations in the DPF feed gas in the range of 3-4 % (vol.) assist the soot combustion with oxygen by increasing the temperature. This rise in temperature is a result of heat generated as a result of hydrogen reactions within the DPF. In order to optimize on-board hydrogen production targets for the regeneration process, a periodical strategy of hydrogen addition to the DPF was implemented. This indicated the margin of hydrogen quantities required.
Keywords: Diesel Particulate Filter, Regeneration, Hydrogen