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With the introduction of stringent particulate number (PN) limits and real driving emission (RDE) requirements, gasoline particulate filters (GPFs) have been widely adopted in Europe and China. GPFs can be coated with different amounts of three-way catalyst (TWC) coating. Some applications use large amounts of washcoat (>100g/L) whereas some don’t use at all. Pressure drop (DP) and PN filtration efficiency (FE) are the top two design criteria. It is important to understand how various coating technologies can be applied to GPF technologies for optimized FE/DP performance. To study filter and coating interaction, a matrix of coated GPFs was prepared and tested for lab DP and vehicle PN based FE. The matrix includes samples with a wide range of washcoat loadings (WCLs), differing coating technologies that target more coating inside GPF filter walls (Tech A) or more on the surface of filter walls (Tech B), and GPF technologies with high and low mean pore size (MPS).

A simple 1-dimensional filter model, with symmetric and asymmetric channels, has been developed to investigate the fundamental behavior and performance of ceramic partial diesel particulate filters (PFs). The governing equations of mass and momentum are similar to those of a full DPF [7, 15]. A standard DPF with the plugs at its inlet face removed has been referred to as a ‘rear-plugged PF’ while, one with the plugs at the outlet face removed has been referred to as a ‘front-plugged PF’ in the present study. Removal of some of the plugs from a standard ceramic DPF reduces the (i) overall pressure drop (ΔP) across the filter, (ii) filtration efficiency (FE) of the DPF, and (iii) manufacturing cost. Partial filters stand a high chance of being deployed in diesel exhaust after-treatment systems for the emerging markets (Brazil, Russia, India, China) that follow Euro 4 emission regulations.

With the introduction of EU6d and CN6 all vehicles with gasoline direct injection and many with port fuel injection engine will be equipped with a gasoline particulate filter (GPF). A range of first generation filter technologies has been introduced successfully, helping to significantly reduce the tailpipe particulate number emissions. The continued focus on particulate emissions and the increasing understanding of their impact on human health, combined with the advanced emission regulations under RDE conditions results in the desire for filters with even higher filtration efficiency, especially in the totally fresh state. At the same time, to balance with the requirements on power and CO2, limitations exist with respect to the tolerable pressure drop of filters. In this paper we will report on a new generation of gasoline particulate filters for uncatalyzed applications.

With upcoming China 6b emission regulation set for full implementation in July 2023, significant efforts are being made within China OEMs to meet the stringent gaseous emission requirements, which reduce gaseous emission limits by 29 to 50% from China 6a for NOx, THC, and CO over the worldwide harmonized light-duty test cycle (WLTC). With current engine and aftertreatment technology, cold-start emissions generated in the first 200 seconds of the WLTC typically makes up most of the total tailpipe emissions result, thus the reduction of cold-start emissions becomes vital to meet regulation requirements. Besides further improvement on engine technology with optimized calibration, a common method to improve cold-start performance is to add more platinum group metals (PGM) into three-way catalyst (TWC). An alternative approach to improve cold-start performance involves using a low mass substrate to enable faster heat up of the TWC.

Shorter new vehicle development time require new engineering methods in the concept and design phase. Therefore methods, which allow an early screening of design alternatives, have been developed and integrated in the design processes. This includes experimental (mostly bench tests) as well as simulation tools. Similar trends can be recognized in the area of exhaust gas aftertreatment. Ever tightening emissions regulations make it necessary in early stages to determine the performance of different aftertreatment concepts. Due to the fact that over 90% of the unconverted emissions occur before the converter is at operating temperature, the heat-up and light-off behavior of the converter is of major importance. In this context a numerical model has been developed to simulate the heat-up and light-off behavior.

The heavy duty (HD) Eu VII regulations, going into effect starting 2027, has aggressive particle number (PN) emissions limits under extended operating conditions compared to existing Eu VI framework. In addition to the proposed hot-start PN limit of 2.0E+11 #/kWh, which is a >65% reduction vs. Eu VI E, the particle size cut-off is being extended from 23nm+ to 10nm+ while also including nearly all field operating conditions such as regeneration events, wider ambient boundaries etc. The tighter limits coupled with a work-based window approach to evaluate emissions is driving the need for the next generation of ultra-high filtration efficiency (FE), diesel particulate filter (DPF) technologies. The current study evaluates the FE performance of different DPF solutions under development, over a range of challenging on-road conditions characterized by frequent high temperature events which are not actively triggered.

As the official proposal for emission regulation Euro 7 has been released by European Commission, PN above 10nm is taken into consideration for the ultrafine particulate emissions control. The challenges of GPF filtration efficiency emerge for the light-duty manufactures to meet the future emission standards. In the present study, a China 6 compliant vehicle was tested to reveal its performance over the China 6 standards and potential to meet the upcoming Euro 7. Three GPF product types (Gen 1, Gen 2, and concept Gen 3) were mounted to the tested vehicle. WLTC tests were conducted on chassis dynamometer in laboratory as well as a self-designed aggressive cycle (“Base Cycle”) tests. To explore the GPFs performance for PN emissions above 10nm against the proposed limit 6.0E11 #/km, PN emission above 10nm were measured in our laboratory tests for both engine out and tailpipe as well as the PN emission above 23nm.