Diagnostics-oriented Model for Automotive SCR-ASC

IF 16.4 1区化学 Q1 CHEMISTRY, MULTIDISCIPLINARY

Accounts of Chemical Research Pub Date : 2023-02-13 DOI:10.36001/ijphm.2023.v14i3.3129

Kaushal K. Jain, Kuo Yang, P. Meckl, Pingen Chen

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引用次数: 0

Abstract

This paper presents a diagnostics-oriented aging model for combined Selective Catalytic Reduction (SCR) and Ammonia Slip Catalyst (ASC) system, along with a model-based on-board diagnostic (OBD) method applied to both test-cell data and on-road data from commercial trucks. The key challenge with model development was unavailability of NOx and NH3 measurements between SCR and ASC. Since it would have been very difficult to calibrate both SCR and ASC dynamics without any measurements between SCR and ASC, therefore ASC was modeled using static look-up tables to determine ASC’s NH3 conversion efficiency and its selectivity to NOx and N2O as a function of temperature and flow rate. The traditional three-state single-cell ordinary differential equation (ODE) model was used for SCR. Hot Federal Test Procedure (hFTP) was used to calibrate the model. Cold FTP (cFTP) and Ramped Mode Cycle (RMC) were used for validation. Results show that the SCR-ASC model can capture the aging signatures in tailpipe NOx, NH3, and N2O reasonably well for cFTP, hFTP, and RMC cycles in the testcell data. After slight re-calibration and combining with a simple model for commercial NOx sensor’s cross-sensitivity to NH3, the model works reasonably well for on-road data from commercial trucks. A model-based on-board diagnostic (OBD) method has been presented with enable conditions designed to detect operating conditions suitable for detecting aging signatures, while minimizing false positives and false negatives. The OBD method is applied to both test-cell and real-world truck data with commercial NOx sensors. Results on test-cell data demonstrate the challenges of robust SCR monitoring even on the limited data set used in this work. The model-based enable conditions are shown to be robust but extremely restrictive as the OBD gets enabled at very few points in the test-cell data. Application on truck data showed that the proposed OBD method can be implemented on commercial trucks with limited sensors. In the truck data, the enable conditions were satisfied on many more points than the test-cell data. Results on truck data show encouraging trends between relative degradation level and the number of miles on four trucks. In future work, these trends will be validated using more data from commercial trucks with known aging levels.

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面向诊断的汽车SCR-ASC模型

本文提出了一种针对选择性催化还原(SCR)和氨滑移催化剂(ASC)组合系统的面向诊断的老化模型，以及一种基于模型的车载诊断(OBD)方法，该方法适用于商用卡车的测试单元数据和道路数据。模型开发的主要挑战是无法获得SCR和ASC之间的NOx和NH3测量数据。由于在没有SCR和ASC之间的任何测量的情况下，很难校准SCR和ASC的动力学，因此ASC使用静态查找表进行建模，以确定ASC的NH3转化效率及其对NOx和N2O的选择性作为温度和流速的函数。SCR采用传统的三态单胞常微分方程(ODE)模型。采用热联邦测试程序(hFTP)对模型进行校准。使用冷FTP (cFTP)和斜坡模式循环(RMC)进行验证。结果表明，SCR-ASC模型可以较好地捕获cFTP、hFTP和RMC循环中尾气NOx、NH3和N2O的老化特征。经过轻微的重新校准，并与商用NOx传感器对NH3交叉灵敏度的简单模型相结合，该模型可以很好地用于商用卡车的道路数据。提出了一种基于模型的机载诊断(OBD)方法，该方法设计了使能条件，以检测适合检测老化特征的操作条件，同时最大限度地减少误报和误报。OBD方法适用于测试单元和实际卡车数据，并配有商用NOx传感器。测试单元数据的结果表明，即使在本工作中使用的有限数据集上，稳健的SCR监测也存在挑战。基于模型的启用条件是健壮的，但由于OBD只在测试单元数据中的很少几个点上启用，因此具有极大的限制。在货车数据上的应用表明，所提出的OBD方法可以在传感器有限的商用货车上实现。在卡车数据中，满足启用条件的点比测试单元数据多很多。卡车数据的结果显示，四辆卡车的相对退化程度与行驶里程之间存在令人鼓舞的趋势。在未来的工作中，这些趋势将使用更多已知老化水平的商用卡车数据进行验证。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Accounts of Chemical Research 化学-化学综合

CiteScore

31.40

自引率

1.10%

发文量

312

审稿时长

2 months

期刊介绍： Accounts of Chemical Research presents short, concise and critical articles offering easy-to-read overviews of basic research and applications in all areas of chemistry and biochemistry. These short reviews focus on research from the author’s own laboratory and are designed to teach the reader about a research project. In addition, Accounts of Chemical Research publishes commentaries that give an informed opinion on a current research problem. Special Issues online are devoted to a single topic of unusual activity and significance. Accounts of Chemical Research replaces the traditional article abstract with an article "Conspectus." These entries synopsize the research affording the reader a closer look at the content and significance of an article. Through this provision of a more detailed description of the article contents, the Conspectus enhances the article's discoverability by search engines and the exposure for the research.