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The Diesel Particulate Filter (DPF) is used on today's diesel vehicles to reduce the amount of soot being released into the atmosphere from diesel exhaust. The DPFs are typically wall-flow filtration devices of various extruded porous ceramic materials with more than 95% efficiency. Once the filter has loaded with soot, the DPF undergoes regeneration where the exhaust temperature is raised to burn off the soot. With the DPF being relatively new aftertreatment technology, the exhaust industry must investigate the acoustic and performance effects of the DPF when added to an exhaust system. In many applications the DPF replaces the exhaust muffler because of limited packaging space. The acoustic performance of the DPF changes with increasing soot density and exhaust backpressure. The acoustic response is measured with physical testing at multiple soot load densities. This study is part of a graduation thesis project for Kettering University[1].

Diesel Particulate Filters have been successfully applied for several years to reduce Particulate Matter (PM) emissions from on-highway applications, and similar products are now also applied in off-highway markets and retrofit solutions. As soot accumulates on the filter, backpressure increases, and eventually exhaust temperatures are elevated to burn off the soot, actively or passively. Unfortunately, in many real-world instances, some duty cycles never achieve necessary temperatures, and the ability of the engine and/or catalyst to elevate exhaust temperatures can be problematic, resulting in overloaded filters that have become clogged, necessitating service attention. An autonomous heat source is developed to eliminate such risks, applying an ignition-based combustor that leverages the current diesel fuel supply, providing necessary temperatures when needed, regardless of engine operating conditions.

Diesel Particulate Filter Systems offer excellent opportunities to reduce the emitted soot through their filtration potential, but periodic burning of the collected soot is necessary. This is referred to as Regeneration, which occurs every few hundred miles and requires gas temperatures to increase to nearly 600°C. As the soot burns, it creates an exothermic response, increasing DPF exit temperatures potentially to 800°C or higher. Such extremes create thermal management concerns as the hot gases exit the tailpipe, particularly during low speeds or idling conditions. Methods to manage such thermal concerns are presented in this study, evaluating passive and active options.

With introductions of stringent diesel engine emission regulations, the DOC and DPF systems have become the mainstream technology to eliminate soot particles through diesel combustion under various operation conditions. Urea-based SCR has been the mainstream technical direction to reduce NOx emissions. For both technologies, low-temperature conditions or cold start conditions pose challenges to activate DOC or SCR emission-reduction performance. To address this issue, mini or full flow burner systems may be used to increase exhaust temperature to reach DOC light-off or SCR initiation temperature by combustion of diesel fuel. In essence, the burner systems incorporate a fuel injector, spray atomization, proper fuel / air mixing mechanisms, and combustion control as independent heat sources.