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Efficient aftertreatment management requires accurate sensing of both particulate filter soot and ash levels for optimized feedback control. Currently a combination of pressure drop measurements and predictive models are used to indirectly estimate the loading state of the filter. Accurate determination of filter soot loading levels is challenging under certain operating conditions, particularly following partial regeneration events and at low flow rate (idle) conditions. This work applied radio frequency (RF)-based sensors to provide a direct measure of the particulate filter soot levels in situ. Direct measurements of the filter loading state enable advanced feedback controls to optimize the combined engine and aftertreatment system for improved DPF management. This study instrumented several cordierite and aluminum titanate diesel particulate filters with RF sensors. The systems were tested on a range of light- and heavy-duty applications, which included on- and off-road engines.

Accelerated ash loading studies provide a cost-effective means of investigating the long-term impacts of ash accumulation in diesel particulate filters (DPFs). Despite a variety of methods adopted in previous studies for accelerated ash loading, evaluation of their impact on DPF behavior has been limited primarily to pressure drop response (with & without soot), and characterization of properties of the resulting ash deposits for comparison with samples from field testing. In the current study, the potential to use ash recovered from field DPFs to perform accelerated ash loading studies is explored. Additionally, anhydrous gypsum as a surrogate for diesel ash was investigated. Benefits of using gypsum include low cost and easy access, safety during handling and testing, and consistency from test to test. Narrow control of particle sizing and composition can help compare performance over a wide range of filter sizes and applications.