Nanjundaswamy, H., Nagaraju, V., Wu, Y., Koehler, E. et al., "Advanced RF Particulate Filter Sensing and Controls for Efficient Aftertreatment Management and Reduced Fuel Consumption," SAE Technical Paper 2015-01-0996, 2015, doi:10.4271/2015-01-0996.
Although designed for the purpose of reducing engine-out Particulate Matter (PM) emissions to meet or exceed mandated emissions regulations, the particulate filter also incurs a fuel economy penalty. This fuel penalty is due to the increased exhaust flow restriction attributed to the PM accumulated in the filter, in addition to fuel consumed for active regeneration. Unlike the soot which may be oxidized through the regeneration process, incombustible material or ash continues to build-up in the filter following each regeneration event. Currently pressure- and model-based controls are used to provide an indirect estimate of the loading state of the particulate filter, in order to manage the filter operation and determine when to regenerate the filter.The challenges associated with pressure- and model-based particulate filter control over real-world operating conditions are well-known. This study investigated the use of a radio-frequency sensor to provide in situ measurements of the loading state of the filter for real-time control of the regeneration process. A model year 2013, heavy-duty diesel engine and aftertreatment system was instrumented with the RF sensor. The first phase of the study evaluated the accuracy of the RF-measured particulate filter soot levels over a range of loading and regeneration conditions. The second phase of the work utilized the RF sensor output to control the start and end of regeneration and compared the regeneration duration and fuel consumption using the RF-based controls with the stock pressure and model-based aftertreatment control system. Results indicate the potential to optimize the regeneration process through RF-enabled real-time controls, providing a reduction in regeneration duration of 15% to 30% relative to current pressure- and model-based systems on a heavy-duty 2013 on-highway engine and aftertreatment platform.