Development of High Accuracy and Quick Light-off NOx Sensor

Todo, Yusuke; Ichikawa, Hiroki; Yotou, Hiroaki; Aoki, Keiichiro; Kawai, Masashi

doi:10.4271/2018-01-0334

Cited by 11 publications

(5 citation statements)

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“…The sensing behavior of various metals and metal oxides has been studied in exhaust gas environments for potential composite electrode materials for NO x sensors [ 6 , 7 , 8 , 9 , 10 , 11 , 12 , 13 , 14 ]. The resistance of the nanostructured grain–grain boundaries of the metal oxide change as a function of the NO x gas upon surface adsorption of NO x molecules, which influences the depletion layer and potential barrier.…”

Section: Introductionmentioning

confidence: 99%

Investigation of an Impedimetric LaSrMnO3-Au/Y2O3-ZrO2-Al2O3 Composite NOx Sensor

et al. 2022

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Composite NOx sensors were fabricated by combining partially and fully stabilized yttria-doped zirconia with alumina forming a composite electrolyte, Y2O3-ZrO2-Al2O3, and strontium-doped lanthanum manganese oxide mixed with gold to form the composite sensing electrode, La0.8 Sr0.2MnO3-Au. A surface chemistry analysis of the composite sensor was conducted to interpret defects and the structural phases present at the Y2O3-ZrO2-Al2O3 electrolyte, as well as the charge conduction mechanism at the LaSrMnO3-Au electrode surface. Based on the surface chemistry analysis, ionic and electronic transport properties, and microstructural features of sensor components, the working principle was described for NOx sensing at the composite sensor. The role of the composite materials on the NOx sensing response, cross-sensitivity to O2, H2O, CO, CO2, and CH4, and the response/recovery rates relative to sensor accuracy were characterized by operating the composite NOx sensors via the impedimetric method. The composite sensors were operated at temperatures ranging from 575 to 675 °C in dry and humidified gas environments with NO and NO2 concentrations varying from 0 to 100 ppm, where the balance gas was N2. It was found that the microstructure of the composite NOx sensor electrolyte and sensing electrode had a significant effect on interfacial reactions at the triple phase boundary, as well as the density of active sites for oxygen reactions. Overall, the composite NOx sensor microstructure enabled a high NOx sensing response, along with low cross-sensitivity to O2, CO, CO2, and CH4, and promoted NO detection down to 2 ppm.

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Section: Introductionmentioning

confidence: 99%

Investigation of an Impedimetric LaSrMnO3-Au/Y2O3-ZrO2-Al2O3 Composite NOx Sensor

et al. 2022

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“…As a potential vision for the next tier of low-cost instrumentation for in-use NOx assessment, there is an actively growing research and regulatory interest to evaluate the feasibility of utilizing existing zirconium dioxide (Zr-O2) NOx sensors (i.e., part of the current aftertreatment configuration) to monitor and report on-board NOx compliance (CARB, 2019;Spears, 2019). However, research studies have highlighted upon measurement cross-interference due to ammonia (NH3) gas and residual oxygen (O2) ions on the reported NOx sensor measurements (Frobert et al, 2013;Soltis et al, 2006;Todo et al, 2018).…”

Section: Problem Statementmentioning

confidence: 99%

“…Substantial developments in stringent emissions regulations and advancements in MD and HD diesel engine/aftertreatment technology are the primary driving force for improvements in accuracy and sensitivity/selectivity of NOx sensor technology. (Frobert et al, 2013;Murray et al, 2017;Sakai et al, 2003;Soltis et al, 2006;Todo et al, 2018). Therefore, to be implemented as a feasible, cost-effective alternative for NOx monitoring, it is essential to gain an in-depth understanding of the impact of cross-sensitivity on sensor-based measurements.…”

Section: Performance Evaluation Of On-board Nox Sensorsmentioning

confidence: 99%

“…The study also presents a protocol where hydrogen (H2) gas is generated by increasing the applied voltage to the electrochemical pump. This resulted reducing the sensor light-off time from 70 seconds to 30 seconds (Todo et al, 2018). A detailed overview of the sensor development research is discussed in the technical paper presented by Todo et al Finally, with regards to measurement technology, due to cost and complexity associated with data acquisition using a PEMS and in view of identifying a costeffective alternative pathway for monitoring of in-use NOx emissions, literature discussed in this study has highlighted upon the detection ability of Zr-O2 NOx sensors.…”

Section: Performance Evaluation Of On-board Nox Sensorsmentioning

confidence: 99%

“…Comparison of output error versus residual O2 concentration on the sensor electrode(Todo et al, 2018) 2.10. SummaryThe literature survey discussed in this study presents an overview of vocational dependency on the performance of SCR systems for NOx reduction, and metric-based performance evaluation of in-use emissions quantification methods.Exhaust gas thermal conditions is a primary challenge associated with limiting SCR performance for NOx abatement across all modes of driving conditions.…”

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Development of an Activity-based Windowing Approach to Evaluate Real-World NOx Emissions from Modern Medium and Heavy-Duty Diesel Trucks

Pondicherry¹

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Development of an Activity-based Windowing Approach to Evaluate Real-World NOx Emissions from Modern Medium and Heavy-Duty Diesel Trucks The introduction of in-use emissions regulations by the United States Environmental Protection Agency (U.S.EPA) requires medium-duty (MD) and heavy-duty (HD) engine manufacturers to demonstrate emissions compliance during in-fleet operation. In the United States (U.S.), the Not-to-Exceed (NTE) method is used to evaluate real-world emissions compliance from on-highway MD and HD trucks. Regulatory agencies, engine manufacturers and research entities have identified that the NTE method incorporates numerous exclusions and evaluates emissions compliance only under selective operating conditions that are favorable for the selective catalytic reduction (SCR) system to reduce oxides of nitrogen (NOx) emissions efficiently. Such operation is typically encountered only by vocations that experience sustained highway driving operation, which is not entirely representative of actual highly diverse real-world operation experienced by the engine/aftertreatment system. Evaluation of real-world driving emissions (RDE) plays a critical role in monitoring and ensuring the performance of emissions control systems. Portable emissions measurement system (PEMS) serves as a robust tool to assess emissions levels during real-world operation. However, utilization of PEMS for large-scale deployment is time-consuming, labor-intensive, and expensive. As a vision of potential elements for a next-tier of in-use NOx monitoring systems, there is an actively growing research and regulatory interest to evaluate the feasibility of using existing on-board NOx sensors for HD on-board NOx compliance. However, research studies have highlighted that NOx sensor measurements are also subjected to cross-sensitivity from other species in the exhaust stream. The journey towards completion of an exciting academic adventure has been a collaborative endeavor, where I would like to thank a huge group of people who have supported me with guidance, motivation, and opportunities as stepping stones to achieve professional growth. First and foremost, I would like to thank my parents Premnath and Ratnamala for providing me with their unconditional love, encouragement, endless support, and countless sacrifices in fulfilling every dream of mine since my childhood. This journey would not have been possible without the support of mom and dad, both emotionally and financially. Thank you for believing in me and always supporting me in my decisions, even through the most challenging times. vi temporarily moved to Detroit for my internship. You have always helped me get through challenging and difficult phases in life, and most importantly supported me with the important decisions of my life. Thank you very much. Special thanks to Ikttesh Chahal for your friendship since the time we met. Thanks for always offering me with your valuable advice whenever needed and believing in me that I had the potential to do more than I actually do and alwa...

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