Soot Load Sensing in a Diesel Particulate Filter Based on Electrical Capacitance Tomography

Abstract

This work presents a novel approach to particulate material (soot) measurement in a diesel particulate filter (DPF) using electrical capacitance tomography (ECT). Modern diesel engines are equipped with DPFs, as well as onboard technologies to evaluate the status of DPF because complete knowledge of DPF soot loading is very critical for robust and efficient operation of the engine exhaust after treatment system. Emission regulations imposed upon all internal combustion engines including diesel engines on gaseous as well as particulate (soot) emissions by environment regulatory agencies. In course of time, soot will be deposited inside the DPFs which tend to clog the filter and hence generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot buildup, regeneration of the DPF must be done as an engine exhaust after treatment process at predetermined time intervals. Passive regeneration increases the exhaust heat to burn the deposited soot while active regeneration injects external energy in, such as injection of diesel into an upstream diesel oxidation catalyst (DOC), to burn the soot. Since the regeneration process consumes fuel, a robust and efficient operation based on accurate knowledge of the particulate matter deposit (or soot load) becomes essential in order to keep the fuel consumption at a minimum. Here we propose a sensing method for a DPF that can accurately measure in-situ soot load using ECT. Lab experimental results show that the proposed method offers an effective way to accurately estimate the soot load in DPF. The proposed method is expected to have a profound impact in improving overall DPF efficiency (and thereby fuel efficiency), and durability of a DPF through appropriate closed loop regeneration operation.