Filtration and Pressure Drop Behavior of High Porosity Gasoline Particulate Filters

Andrea  Strzelec, Texas A&M University

Gasoline Direct Injection (GDI) engines blend the gasoline and diesel platforms to significantly improve the fuel efficiency of light duty passenger gasoline vehicles. However, the higher efficiency derived from directly injecting the fuel has a trade off in emissions, especially particulates. [SAE 1999-01-1530] With stringent emission regulations, there is a need to reduce PM emissions from GDI engines. While changes to lower engine out emissions are preferred, GPFs may still be required. High filtration efficiency (>90%) will likely be needed to meet particle number standards such as EU6 6X10¹¹PN. Current GPF technologies typically involve wall flow filters with or without catalytic washcoats, which usually offer filtration efficiencies around 70-80%. Research has been carried out on the design of wall flow filters and washcoating techniques to improve the filtration efficiency while balancing the backpressure tradeoff.

Currently, the understanding of how GDI particulates differ from traditional gasoline or diesel with regard to filtration in a particulate filter is not fully developed. Additionally, there is currently a lack of cost-effective emissions control devices for this combustion strategy. Diesel particulate filters have only moderate clean filtration efficiency (~60% capture) and rely on the soot cake that quickly builds up in the filter to achieve high filtration efficiencies. GDI engines produce smaller and less particles than their diesel counterparts [SAE 2000-01-0255 and 2010-01-0789] making the development of a soot cake improbable.

The objective of this project is to study the fundamental filtration behavior of fresh, lightly ash-loaded and modified GPFs using model particulates to investigate parameters such as GDI-range particle sizes and space velocity to promote the development of optimal filtration systems for the smaller particulate matter encountered in GDI combustion.

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