Research Papers

Development of a Soot Load Sensor Using Electrical Capacitance Imaging

[+] Author and Article Information
Ragibul Huq

Cummins, Inc.,
Columbus, IN 47201
e-mail: ragibul.huq@cummins.com

Sohel Anwar

Department of Mechanical Engineering,
Indiana University Purdue University
Indianapolis (IUPUI),
Indianapolis, IN 46202
e-mail: soanwar@iupui.edu

Contributed by the Dynamic Systems Division of ASME for publication in the JOURNAL OF DYNAMIC SYSTEMS, MEASUREMENT, AND CONTROL. Manuscript received October 13, 2014; final manuscript received April 3, 2015; published online August 14, 2015. Assoc. Editor: Junmin Wang.

J. Dyn. Sys., Meas., Control 137(11), 111009 (Aug 14, 2015) (10 pages) Paper No: DS-14-1412; doi: 10.1115/1.4030355 History: Received October 13, 2014

This paper presents an innovative approach for measuring particulate matter deposition (soot load) in a diesel particulate filter (DPF) using electrical capacitance imaging. Emission regulations on diesel engines for gaseous as well as particulate matter (soot) emissions are getting stringent every few years by the environment regulatory agencies. Modern diesel engines are equipped with DPFs, as well as on-board technologies to evaluate the status of DPF, because complete knowledge of DPF soot load is very critical for robust and efficient operation of the engine exhaust after treatment system. In course of time, soot will be deposited inside the DPF which will clog the filter and generate a back pressure in the exhaust system, negatively impacting the fuel efficiency. To remove the soot build-up, regeneration (active or passive) of the DPF must be done as an engine exhaust after treatment process periodically. Since the regeneration process consumes fuel, a robust and efficient operation based on accurate knowledge of the soot load becomes essential in order to keep the fuel consumption at a minimum. In this paper, we propose a novel sensing method for a DPF that can measure in situ soot load using electrical capacitance imaging. Experimental results show that the proposed method offers an effective way to measure the soot load in DPF. The proposed method is expected to have a profound impact in improving overall DPF filtering efficiency and durability of a DPF through appropriate closed-loop regeneration operation.

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Huq, R. , and Anwar, S. , 2014, “An Electrical Capacitance Based Measurement Method for Soot Load Estimation in a Diesel Particulate Filter,” IFAC World Congress, Cape Town, South Africa, Aug. 24–29, pp. 8463–8468.
Huq, R. , and Anwar, S. , 2013, “Soot Load Sensing in a Diesel Particulate Filter Via Electrical Capacitance Tomography,” ASME Paper No. IMECE2013-62819.


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Fig. 1

Porous walls of a DPF [1]

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Fig. 2

DPF diagnosis regulatory requirements [4]

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Fig. 6

Electrode arrangement for capacitance measurement

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Fig. 5

Electrical capacitance imaging systems process flow chart

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Fig. 4

Empty, completely filled, and partially filled cases

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Fig. 3

Empty, completely filled, and partially filled cases

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Fig. 7

Square pixel grid for tomographic image generation

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Fig. 10

Output voltage measured at 1.6–1.7 V for the first 5 ms

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Fig. 11

Relationship between output voltage and capacitance

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Fig. 8

Real part of dielectric constant and soot layer thickness [8]

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Fig. 9

5V AC input at 1 MHz in 60 pF capacitor circuit

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Fig. 12

Four capacitor plate positions in the ECT and a 2 × 2 pixel grid

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Fig. 13

Sensitivity matrix

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Fig. 14

Particulate deposition and tomographic image

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Fig. 16

Experimental setup: (a) filter model, (b) soot model, (c) NI-DAQ, (d) data acquisition program, (e) signal generator, (f) data acquisition circuit, (g) blower, and (h) material weighing

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Fig. 17

Four electrode arrangement for capacitance measurement

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Fig. 18

Output voltage versus the accumulation of Printex U as well as dry sand (uniform distribution). (a) Output voltage (Vab) versus material deposition, (b) output voltage (Vac) versus material deposition, (c) output voltage (Vad) versus material deposition, (d) output voltage (Vbc) versus material deposition, (e) output voltage (Vbd) versus material deposition, and (f) output voltage (Vcd) versus material deposition.

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Fig. 19

DPF with four electrode capacitor plates

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Fig. 20

Square pixel grid for tomographic image generation

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Fig. 21

10% increments along circumference from 0% fill to 100% fill for Printex U

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Fig. 22

10% increment full from 0% fill to 100% fill for Printex U (uniform distribution)

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Fig. 15

Proposed ECT sensors architecture for a DPF



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