While many potentially useable sensors available in the marketplace today target on-board diagnostics and engine-control applications, more knowledge is needed about how these particle sensors perform in engine-exhaust applications where temperature, flow and particle characteristics change under different engine operating conditions.

Further, current research and evaluation is inconclusive in determining whether or not a particular particle sensor is sensitive to:

• Particle size
• Number
• Surface area
• Volume
• Mass
• Charge

In addition, SwRI adds, more knowledge is needed about how well particular particle sensors correlate with soot mass or with total (soot plus volatile) particulate matter (PM) mass since, by definition, total PM mass is a regulated property and soot mass is not a regulated property.

Although particle sensors are expected to become a critical OBD component for detecting particle emissions failure from downstream of an exhaust DPF, it is critical that these sensors prove they can perform their tasks before they are launched on a commercial scale.

The PSPD consortium will investigate how particle sensors perform under different exhaust parameters, including temperature, velocity, size distribution, number and mass concentration.

SwRI will capitalize on its knowledge and expertise in the area of engine and particle science and technology to conduct this work. Using SwRI’s resources, several engine exhaust variables can be controlled, including particle size distribution; number concentration; mass concentration; temperature; flow rate; and backpressure.

Before particle sensors are installed on vehicles in large numbers, we need to get a great deal more information on how effective they are in measuring particulate matter. This consortium will help the industry determine whether certain particle sensors are sensitive to changes in particle size, number, surface area, volume, mass, charge and morphology. It will also help determine how durable and repeatable they are in the harsh exhaust environment.

—Dr. Imad A. Khalek, a senior program manager in SwRI’s Engine, Emissions and Vehicle Research Division who leads the newly formed consortium

Test data produced by the consortium will free resources of original equipment manufacturers, allowing them to concentrate on product development rather than performing particle-sensor assessments.

Five engine manufacturers and three sensor makers from the United States, Japan, Germany and France have joined the PSPD consortium to date. The annual membership fee is $55,000, with the first year beginning 15 April 2012. A second optional year with the same fee is planned for Year 2. Year 1 focuses on sensor performance and Year 2 focuses on sensor durability.