The increased adoption of Diesel Particulate Filters to comply with the proposed particle number limit encompassed in Euro 6 has led to additional development and quality control requirements. DPFs present a more complex challenge than a three way catalyst, in that their performance depends greatly on their sootload, which in turn depends on the history of the DPF/engine combination.
DPG: DPF Testing System
Quality control of DPFs represents a significant cost- the volume of DPF production coupled with the cost of running engine dynamometers means that the hourly costs of a test program can be very large. Achieving good repeatability and reproducibility with a diesel engine is a demanding task, requiring tight control of many parameters and the attention of highly skilled personnel.
This difficulty in achieving good R&R also poses problems in an R&D environment- evaluating the performance of a DPF development is impossible if the test can not be controlled tightly enough. This can be a significant problem where the DPF affects the engine being used to test it- for example a DPF with a high backpressure will require more power input to the engine to compensate for the backpressure. This will cause NOx levels to rise, and may cause passive regeneration.
To address these problems, Cambustion offer the DPG: DPF Testing System. Although diesel fuelled the DPG uses a constant pressure burner rather than an engine, and incorporates sophisticated monitoring and control to ensure repeatable performance. The DPG can load diesel soot onto a filter while monitoring and recording temperatures, flows and pressures. By operating at different conditions the DPG can regenerate a DPF, raising the inlet temperature as high as 800°C. Exotherms may be monitored- as well as providing a convenient way of regenerating a tested DPF, the DPG can also be used for more sophisticated tests such as "maximum soot load" or "cut to idle" tests.
By operating at ultra-low NOx levels and decoupling the burner from the DPF under test, the DPG allows unprecedented insights into DPF operation.
DMS Series particulate analyzers
Cambustion's DMS series particulate analyzers offer real-time data on particle size, number and mass. With fully integrated sampling and dilution, they can sample pre or post DPF, allowing calculation of filtration efficiencies and other DPF performance studies. Unique real-time software allows the DMS series to output data which correlates with the proposed PMP number standard (n/km), while a response time (T10-90%) as low as 200ms allows insights into transient engine and DPF operation.
Cambustion's unique Dual Sampling Accessory for the DMS series allows electrical switching of the sample point between two locations- for example pre- and post-DPF.