FY2011 Progress Report: Agreement 8697 - NOx Sensor Development

One of 106 reports in the series: Fiscal Year 2011 available on this site.

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Objectives are: (1) Develop an inexpensive, rapid-response, high-sensitivity and selective electrochemical sensor for oxides of nitrogen (NO{sub x}) for compression-ignition, direct-injection (CIDI) OBD II systems; (2) Explore and characterize novel, effective sensing methodologies based on impedance measurements and designs and manufacturing methods that are compatible with mass fabrication; and (3) Collaborate with industry in order to (ultimately) transfer the technology to a supplier for commercialization. Approach used is: (1) Use an ionic (O{sup 2-}) conducting ceramic as a solid electrolyte and metal or metal-oxide electrodes; (2) Correlate NO{sub x} concentration with changes in cell impedance; (3) Evaluate sensing mechanisms and ... continued below

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Woo, L Y & Glass, R S November 1, 2011.

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  • Main Title: FY2011 Progress Report: Agreement 8697 - NOx Sensor Development
  • Series Title: Fiscal Year 2011

Description

Objectives are: (1) Develop an inexpensive, rapid-response, high-sensitivity and selective electrochemical sensor for oxides of nitrogen (NO{sub x}) for compression-ignition, direct-injection (CIDI) OBD II systems; (2) Explore and characterize novel, effective sensing methodologies based on impedance measurements and designs and manufacturing methods that are compatible with mass fabrication; and (3) Collaborate with industry in order to (ultimately) transfer the technology to a supplier for commercialization. Approach used is: (1) Use an ionic (O{sup 2-}) conducting ceramic as a solid electrolyte and metal or metal-oxide electrodes; (2) Correlate NO{sub x} concentration with changes in cell impedance; (3) Evaluate sensing mechanisms and aging effects on long-term performance using electrochemical techniques; and (4) Collaborate with Ford Research Center to optimize sensor performance and perform dynamometer and on-vehicle testing. Work in FY2011 focused on using an algorithm developed in FY2010 in a simplified strategy to demonstrate how data from controlled laboratory evaluation could be applied to data from real-world engine testing. The performance of a Au wire prototype sensor was evaluated in the laboratory with controlled gas compositions and in dynamometer testing with diesel exhaust. The laboratory evaluation indicated a nonlinear dependence of the NO{sub x} and O{sub 2} sensitivity with concentration. For both NO{sub x} and O{sub 2}, the prototype sensor had higher sensitivity at concentrations less than {approx}20 ppm and {approx}7%, respectively, compared to lower NO{sub x} and O{sub 2} sensitivity at concentrations greater than {approx}50 ppm and {approx}10.5%, respectively. Results in dynamometer diesel exhaust generally agreed with the laboratory results. Diesel exhaust after-treatment systems will likely require detection levels less than {approx}20 ppm in order to meet emission regulations. The relevant mathematical expressions for sensitivity in different concentration regimes obtained from bench-level laboratory evaluation were used to adjust the sensor signal in dynamometer testing. Both NO{sub x} and O{sub 2} exhibited non-linear responses over the concentration regimes examined (0-100 ppm for NO{sub x} and 4-7% for O{sub 2}). Adjusted sensor signals had better agreement with both a commercial NO{sub x} sensor and FTIR measurements. However, the lack of complete agreement indicated that it was not possible to completely account for the nonlinear sensor behavior in certain concentration regimes. The agreement at lower NO{sub x} levels (less than 20 ppm) was better than at higher levels (50-100 ppm). Other progress in FY2011 included dynamometer testing of sensors with imbedded heaters and protective housings that were mounted directly into the exhaust manifold. Advanced testing protocols were used to evaluate the sensors. These experiments confirmed the potential for sensor robustness and durability. Advanced material processing methods appropriate for mass manufacturing, such as sputtering, are also being evaluated. A major milestone for this past year was the licensing of the LLNL NO{sub x} sensor technology to EmiSense Technologies, LLC. EmiSense has extensive experience and resources for the development of emission control sensors. A CRADA is in development that will allow LLNL to work in partnership with EmiSense to bring the LLNL NO{sub x} sensor technology to commercialization. Ford Motor Company is also a partner in this effort.

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PDF-file: 11 pages; size: 6.4 Mbytes

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  • Report No.: LLNL-TR-510234
  • Grant Number: W-7405-ENG-48
  • DOI: 10.2172/1035304 | External Link
  • Office of Scientific & Technical Information Report Number: 1035304
  • Archival Resource Key: ark:/67531/metadc842045

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  • November 1, 2011

Added to The UNT Digital Library

  • May 19, 2016, 3:16 p.m.

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  • Nov. 28, 2016, 6:22 p.m.

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Woo, L Y & Glass, R S. FY2011 Progress Report: Agreement 8697 - NOx Sensor Development, report, November 1, 2011; Livermore, California. (digital.library.unt.edu/ark:/67531/metadc842045/: accessed September 25, 2017), University of North Texas Libraries, Digital Library, digital.library.unt.edu; crediting UNT Libraries Government Documents Department.