Motoring ahead towards new diesel engines Hybrid conventional-homogeneous charge compression ignition (HCCI) diesel engines offer the promise of combining lower emissions of HCCI technology with the versatility of conventional diesel motors. But this will require a new type of particulate filter technology. Energy © Shutterstock Road transport is one of the main culprits in the generation of climate-changing greenhouse gas (GHG) emissions. Vehicles on our roads are, together, responsible for about a quarter of all of the EU’s GHG emissions, making it the second highest emitter after the energy sector. To address this challenge while preserving the mobility of citizens, the EU has over the years set increasingly rigorous emission standards, while encouraging the development of less-polluting, fuel-efficient vehicles. One promising technology in this regard is diesel engines which operate on the HCCI principle. One of the major drawbacks of this technology is the relatively small power range of these engines. One way around this is to develop combined engines that operate as HCCI at low loads, as hybrid HCCI-conventional engines at medium loads and as conventional diesel engines at high and full loads. This will require a new type of diesel particulate filter (DPF) to bring the emission of this combined engine to below Euro V levels. The EU-funded ‘Innovative particle trap system for future diesel engines’ (IPSY) project worked to develop an alternative DPF approach that would reduce the soot combustion temperature for hybrid HCCI engines. The project focused on a new filter design with internal heat recovery capability and an advanced multifunctional catalyst that enhances the catalytic soot conversion. IPSY set up a database of HCCI exhaust emissions and soot morphology and developed a new particulate trap system with enhanced catalytic effect. The project formulated an advanced operations and control strategy for the new system and tested and investigated its potential. The advanced features of the IPSY filter system were based on higher soot-to-catalyst contact. %Based on the first year’s results of the analysis of internal heat recovery and the developments in the multifunctional catalyst synthesis and application, a full-scale prototype was built. This prototype was tested against IPSY’s emission targets in the first half of the second year. Two prototypes – which were equipped with pressure and temperature sensors to monitor the filter operation during testing on the real engine exhaust – were then manufactured. Testing was carried out on both HCCI and conventional engines, both prior to and after ageing. The filtration efficiency of the prototype filter was excellent and remained so even after ageing, while its catalytic activity was significantly higher than and its backpressure comparable to conventional filters. The IPSY prototype also exhibited huge potential for reducing the fuel penalty of current DPF regeneration operation. This means that, combined with an optimised operation strategy, the new IPSY filter represents a complete and new DPF concept that can contribute to the future compliance of HCCI engines with European emission standards.
