Heavy-Duty Diesel Particulate Filter (DPF) Durability 

Southwest Research Institute® (SwRI®) is offering a cooperative research program to develop accelerated durability test procedures for heavy-duty diesel particulate filters (DPF). The federal limit for particulate emissions from heavy-duty diesel engines will decrease from 0.1 g/hp-hr to 0.01 g/hp-hr in 2007. The use of DPFs is considered to be the only diesel aftertreatment technology for meeting the 2007 federal particulate limit. Heavy-duty engine and vehicle manufacturers plan to install DPFs as original equipment with a useful life of 435,000 miles. An accelerated physical durability test is needed to develop durable DPF assemblies.

The basis for developing a DPF durability test will be the physical environments of in-use particulate filters on a variety of heavy-duty and medium-duty vehicles. Thermal, exhaust stream pressure, and vibration environments will be measured on DPFs installed on vehicle exhaust systems. These environments will be incorporated into appropriate test methods and specifications.

Objective

The objective of the Heavy-Duty DPF Durability pro-gram is to pursue precompetitive information on exhaust system environments and develop durability test specifi-cations. The DPF durability test can be used to reduce the amount of time required to validate DPF designs for on-vehicle use. The three-phase research program consists of establishing exhaust system environments, developing an environmental simulation test procedure, and validating the test with generic DPF designs.
 

Diesel Particulate Filter. Components of a DPF are the cordierite or silicon carbide filter element and a steel container. Not shown is the filter mount material used for holding the filter in the container.

Exhaust System Environments

Phase 1 of the research program involves selecting test vehicles for a variety of vehicle sizes, engine power, and DPF positions. All test vehicles will be fitted with a DPF and driven on-road to record exhaust system environ-mental data.

Environment Simulation Test

In Phase 2, test methods, apparatus, and specifications will be developed using the data from Phase 1. The goal will be to develop an accelerated test procedure. Resonance test techniques will be used to determine DPF structural integrity during the progress of a durability test.

DPF Durability Test Validation

In Phase 3, a number of DPFs will be tested using the newly developed test procedure. This phase is intended to complete the test procedure development by valid-ating it for commercial use. A test matrix of DPFs with changes to specific design parameters will be used to validate the test.
 

Example of Vibration Power Spectral Density (PSD) for Durability Test. Actual PSD will be derived from on-vehicle measurements.

Design Parameters

Using the developed heavy-duty DPF durability test protocol, member companies can individually establish their own competitive design parameters, including:

• Canning techniques
• Container materials
• Filter material and geometry
• Filter mount material (mat)
• Mat gap bulk density (GBD)
• Mat temperature gradient

Benefits

Information from this program will be of interest to a variety of industries, such as engine and truck manufac-turers, exhaust system and component suppliers, and filter and mounting mat suppliers. Using this durability test procedure, DPF designs can be evaluated in an efficient and timely manner before field testing begins.

It will allow researchers to uncover DPF design failure modes and propose design changes to increase DPF durability and rapidly retest to confirm the design changes. This information can be used for durability testing of other diesel aftertreatment devices such as oxidation catalysts, NO_x catalysts, and SCRs.

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